Symposium Organizers
Suzana Nunes, King Abdullah University of Science and Technology (KAUST)
Mainak Majumder, Monash University
Kuo Lun (Allan) Tung, NTU Taiwan
Ranil Wrickamasinghe, University of Arkansas
SM7.1: Biomimetic, Bioinspired Membranes and Bioseparations I
Session Chairs
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 123
11:30 AM - *SM7.1.01
Highly Selective Biomimetic Ion/Water Channels
Mihail Barboiu 1 2
1 , Institut Europeen des Membranes, Montpellier France, 2 Centre of Advanced Research in Bionanoconjugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry, Iasi Romania
Show AbstractAquaporins (AQPs) are biological water channels known for fast water transport (~108-109 molecules/s/channel) with ion exclusion. Few synthetic channels have been designed to mimic this high water permeability, and none reject ions at a significant level. Here, we report artificial imidazole-quartet water channels with 2.6-Å pores, similar to AQP channels, that encapsulate oriented dipolar water-wires in a confined chiral conduit. These channels are able to transport ~106 water molecules per second, which is within two orders of magnitude of AQPs’ rates, and reject all ions except protons. The proton conductance is high (~5 H+/s/channel) and approximately half that of the M2 proton channel at neutral pH. Chirality is a key feature influencing efficiency. Natural KcsA channel conduct K+ cations at high rates excluding Na+ cations. Biomimetic artificial channels have been designed in order to mimick the ionic activity of KcSA channels, but simple artificial systems presenting high K+/Na+ selectivity are rare. Here we report an artificial ion-channel of H-bonded hexyl-benzoureido-15-crown-5-ether, where K+ cations are highly preferred to Na+ cations. The K+-channel conductance are interpreted as arising in the formation of oligomeric highly cooperative channels, resulting in the cation-induced membrane polarization and enhanced transport rates without or under pH-active gradient. These channels are selectively responsive to the presence of K+ cations, even in the presence of a large excess of Na+. From the conceptual point of view these channels express a synergistic adaptive behaviour: the addition of the K+ cation drives the selection and the construction of constitutional polarized ion-channels toward the selective conduction of the K+ cation that promoted their generation in the first place. [1] M. Barboiu and A. Gilles, Acc. Chem. Res. 2013, 46, 2814–2823. [2] M. Barboiu, Angew. Chem. Int. Ed. 2012, 51, 11674-11676. [3] Y. Le Duc, M. Michau, A. Gilles, V. Gence, Y.-M. Legrand, A. van der Lee, S. Tingry, M. Barboiu, Angew. Chem. Int. Ed. 2011, 50(48),11366-11372. [4] E. Licsandru, I. Kocsis, Y.-x. Shen, S. Murail, Y.-M. Legrand, A. van der Lee, D. Tsai, M. Baaden, M. Kumar, M. Barboiu, J. Am. Chem. Soc., 2016, 138, 5403-5409. [5] M. Barboiu, Chem. Commun., 2016, 52, 5657- 5665. [6] A. Gilles, M. Barboiu, J. Am. Chem. Soc., 2016, 138(1), 426-432. [7] Z. Sun, A. Gilles, I. Kocsis, Y. M. Legrand, E. Petit, M. Barboiu, Chem. Eur. J., 2016, 55, 4130 – 4154. [8] Z. Sun, M. Barboiu, Y.M. Legrand, E. Petit, A. Rotaru, Angew. Chem. Int. Ed. 2015, 54, 14473-14477. The project leading to this work has received funding from European Union’s Horizon 2020 reserch and Innovation Programme under Grant Agremment SUPRACHEMLAB no 667387
12:00 PM - *SM7.1.02
Artificial Water Channels—Bioinspired and Energy-Efficient Filtration Materials
Manish Kumar 1 , Yuexiao Shen 1
1 Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractWater purification is emerging as an important challenge in the 21st century, globally,1 and even in our own backyard with accidents of unsafe and scarce drinking water in Milwaukee, Flint and California in recent years. Membrane-based technologies that have been extensively used to produce fresh water from seawater and to purify microbiologically and chemically contaminated water are energy intensive. Nature provides excellent examples for energy-efficient desalination and water filtration. Mangrove trees purify saline water through its root systems with minimal energy input (Fig. A). In cell membranes, including those in the mangrove roots (Fig. B), biological water channel proteins aquaporins (AQPs) (Fig. C) conduct single channel water transport while excluding all other molecules.2 This mechanism has inspired us to study on the design of artificial structures that mimic AQPs and led to the exciting development of biomimetic membranes for energy-efficient desalination using these structures.3 Artificial water channels combine the advantages of AQPs and their analogues, carbon nanotubes (CNTs), and improve upon them through their relatively simple synthesis and chemical stability4. Combining the high water conductance (Fig. E) and the high pore density (Fig. F) of artificial water channel-based membranes,5,6 these materials are promising energy-efficient separation materials for the future (Fig. G).
Fig. Bioinspired artificial water channels-based membranes are designed for energy-efficient desalination. (A-B) Mangrove lives in the sea and rely on its root system to purify sea water. (C) Biological water channel proteins aquaporins (AQPs) in the cell membranes of the mangrove root system have high water transport rate while rejecting any other solutes and ions. (D) Peptide-appended pillar[5]arene (PAP) artificial water channels mimic the structure of AQPs. (D) The water conductance of PAP channels are close to that of AQPs and carbon nanotubes (CNTs). (E) PAP channels can form densely packed lipid or polymer membranes. (G) Combined the high water conductance and the high pore density of PAP channel-based membranes, these materials are the promising energy-efficient separation materials in the future.
Reference
1. Shannon, M. A. et al. Nature 452, 301-310, (2008). 2. Agre, P. Angew. Chem. Int. Ed. 43, 4278-4290, (2004). 3. Shen, Y.-x. et al. J. Membr. Sci. 454, 359-381, (2014). 4. Shen, Y.-x. et al. Proc. Natl. Acad. Sci. U.S.A. 112, 9810-9815, (2015). 5-6. Shen, Y.-x. et al. in preparation.
12:30 PM - *SM7.1.03
Biohybrid and Biomimetic Membranes for Sustainable Production and Separations
Rosalinda Mazzei 1 , Abaynesh Gebreyohannes 1 2 , Teresa Poerio 1 , Pierre Aimar 3 , Ivo Vankelecom 4 , Lidietta Giorno 1
1 , Institute on Membrane Technology, National Research Council of Italy, ITM-CNR, Rende (CS) Italy, 2 Centrum voor Oppervlaktechemie en Katalyse, Faculteit Bio-ingenieurswetenschappen, KU Leuven, Leuven Belgium, 3 Laboratoire de Génie Chimique, Université de Toulouse; CNRS, INPT, UPS, Toulouse France, 4 , Centrum voor Oppervlaktechemie en Katalyse Dept. M2S, Faculteit Bio-ingenieurswetenschappen, Leuven Belgium
Show AbstractBiomolecules associated with nanocomposite are an emerging and very interesting systems inspired by nature. They can be formed by the integration of natural polymers and inorganic solids e.g., iron based magnetic particles on the nanometer scale. The bionanocomposites are thus combination of synthetic and biological polymers. Hence it involves coating inorganic particles with synthetic polymers to introduce surface functional groups which are subsequently used for the anchorage of biopolymers. Then the further integration of biomolecules, generally enzymes, permits to obtain bioinspired and biomimetic
Few examples are reported in literature about the use of bionanocomposite integrated with membrane bioreactors. However it seems a very interesting and potential multilevel biohybrid membrane systems able to solve some crucial problems related to the use of BMR.
In a recent work [1], magnetic biocomposites were used in combination with membrane bioreactor to develop a system able to reduce fouling during pectins filtration. The bionanocomposite promote self cleaning properties to the membrane during operation. The bionanocomposite having magnetic properties can be removed once needed by reversing the a magnetic field. This reversible deposition of the enzyme on the membrane facilitates the removal of the enzyme before membrane cleaning, thus avoiding enzyme denaturation due to change in the membrane microenvironment that could be imposed by membrane cleaning conditions. The potentialities of the approach will be highlighted for different type of bioprocessing.
[1]Gebreyohannes A. Y , R. Mazzei, T. Poerio, P. Aimar, Vankelecom I.F.J., Giorno L., RSC Advances, 2016, DOI: 10.1039/C6RA20455D
SM7.2: Biomimetic, Bioinspired Membranes and Bioseparations II
Session Chairs
Mihail Barboiu
Lidietta Giorno
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 123
2:45 PM - *SM7.2.01
A New Use for MOFs—Stopping Physical Aging in Glassy Polymers for Exceptional Separation Performance
Matthew Hill 1
1 , CSIRO, Clayton South, Victoria, Australia
Show AbstractAging in super-glassy polymers such as poly(trimethylsilylpropyne) (PTMSP) prohibits it from being used in polymer membranes for separating gas mixtures. While these polymers are initially very porous and large amounts of gas can selectively pass through them, they quickly pack into a denser phase becoming much less porous and permeable. This age-old problem has been solved by the use of an ultraporous additive that allows PTMSP to maintain its low-density, porous initial state by absorbing a portion of the polymer chains within its pores, and holding them in position. This is the first time that this aging process has been stopped in PTMSP without diminishing its properties when prepared as a gas separation membrane.1,2 In fact, the membrane properties are enhanced with an additive,3 and over approximately one year of long-term measurements show that the performance is maintained.
The addition of a very specific porous microparticle forms an interwoven nanocomposite with PTMSP, freezing the structure and hence stopping the aging process, but doing so whilst increasing the permeability and maintaining the selectivity. Porous Aromatic Frameworks (PAFs) are carbon-based structures formed by the self-condensation of tetrahedral monomer nodes to establish an ultraporous array.4 The regular nanopores of around 1.2 nm diameter are attractive for the intercalation of polymer side-chain components when incorporated within the PTMSP matrix, thereby freezing the as-cast lower-density polymer structure in place and stopping the aging process.5,6 This mechanism is distinct from the enhanced permeability effect of non-porous nanoparticle and porous nanoparticle additions to PTMSP that prop open the polymer chains at the nanoparticle/polymer boundary but do not prevent aging.
1. C. H. Lau, P. T. Nguyen, M. R. Hill,* A. W. Thornton, K. Konstas, C. M. Doherty, R. J. Mulder, L. Bourgeois, A. C. Y. Liu, D. J. Sprouster, J. P. Sullivan, T. J. Bastow, A. J. Hill, D. L. Gin, R. D. Noble, Forever Young: Ending Aging in Super Glassy Polymer Membranes, Angewandte Chemie. 2014, 126,21,5426.
2. Lyndon, R.; Konstas, K.; Ladewig, B. P.; Hill, M. R. GAS SEPARATION PROCESSES TW8699/AU/PROV, 26/7/12, 2012.
3. Thornton, A.W., Dubbeldam, D., Liu, M.S., Ladewig, B.P., Hill, A.J., Hill, M. R*. Feasibility of Zeolitic Imidazolate Frameworks for use in Gas Separation Membranes, Energ. Environ. Sci. 2012; 5:7637.
4. Konstas, K., Taylor, J.W., Thornton, A.W., Doherty, C.M., Lim, W.X., Bastow, T.J., Kennedy, D.F., Wood, C.D., Cox, B.J., Hill, J.M., Hill A.J., Hill, M. R*. Lithiated Porous Aromatic Frameworks with Exceptional Gas Storage Capacity, Angew. Chem. Int. Edit. 2012; 51:6639
5. C. H. Lau, K. Konstas, A. W. Thornton, A. C. Liu, S. Mudie, D. F. Kennedy, S. C. Howard, A. J. Hill, M. R. Hill, Angew. Chem. Int. Ed. 2015, 10.1002/anie.201410684
6. C. H. Lau, X. Mulet, K. Konstas, C. M. Doherty, M. A. Sani, F. Separovic, M. R. Hill, C. D. Wood, Angew. Chem. Int. Ed. 2016, 55 (6), 1998-2001.
3:15 PM - SM7.2.03
Synthesis of Multi-Functional Surfaces and Coatings Inspired from the Peristome of Carnivorous Nepenthes
Zheng-Jun Shih 1 , Yu-Min Lin 1 , Ching-Yu Yang 1 , Po-Yu Chen 1
1 Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu Taiwan
Show AbstractCarnivorous plants have developed unique capturing mechanisms to survive in infertile environments. The pitcher plant Nepenthes utilizes a specialized leave to attract and trap insects in wet and moist weather. The peristome on the top of trap can be completely wetted forming a superhydrophilic, water-lubricated slippery trap. Hierarchical ridge-like and anisotropic microstructures of peristome enhance wetting efficiency. Inspired from the peristome of Nepenthes, surfaces with hierarchical structures were synthesized by PDMS replica molding, micro-fabrication and 3D printing methods. Atmospheric-pressure plasma treatment and hydrophilic functional groups grafting were further applied to modify surface properties from superhydrophobic to hydrophilic/superhydrophilic. Micro-/nano-structural features and surface morphology were characterized by SEM, TEM and AFM. Wetting behavior was evaluated by static and dynamic contact angle measurements and high speed camera. Through materials selection, structural design and surface modification, multifunctional bio-inspired surfaces with tunable wettability, superior self-cleaning abilities, high transparency, flexibility, mechanical and thermal stability were successfully synthesized which can be potentially applied in various fields.
3:30 PM - *SM7.2.04
Ligand-Protein Interactions in New Affinity Membranes for IgG Purification
Eleonora Lalli 1 , Cristiana Boi 1 , Giovanni Giovenzana 2 , Carlo Cavallotti 3 , Giulio Sarti 1
1 , University of Bologna, Bologna Italy, 2 , University of Piemonte Orientale, Novara Italy, 3 , Politecnico di Milaano, Milano Italy
Show AbstractWe have recently designed and synthesized a series of small molecules acting as synthetic ligands for IgG. Such ligands are the results of several years of study on the nature of interaction of monoclonal antibodies, and in particular IgG’s, with their natural ligand, namely protein A, and with the available synthetic ligands. An integrated approach that combines molecular dynamics with experimental activity and crystallographic studies was used to find a new binding site of IgG, which lies in the proximity of the main binding site of protein A, known as the consensus binding site, but is not overlapped with it. These small ligands were thus specifically computationally designed to bind to the new binding site of IgG that is, according to our simulations, more easily accessible than the consensus binding site.
Preliminary experiments with commercial cellulosic membranes decorated with these ligands, in particular with one of them called HPTA, showed promising properties in terms of binding capacity, selectivity and overall recovery of IgG from complex mixtures. Indeed, there are several issues related to residual non-specific binding and to the antibody recovery obtained in the elution step, that appear to be associated rather to the membrane surface and to the spacer arm effects than to the ligand itself. That is demonstrated through studies on the influence of the endcapping protocol and of the spacer arm on the new ligand selectivity, using pure solutions of IgG, BSA and lysozyme, as well as mixtures of IgG and BSA and lysozyme.
The effects of the properties of the membrane surface in proximity of the affinity ligand are studied by functionalizing part of the surface with histidines or similar residues containing amines, that are able to change their protonation state as a function of pH. A modification of the charge of the surface is indeed expected to change drastically the energy of interaction of the adsorbed antibody with the surface, thus improving selectivity.
4:30 PM - *SM7.2.05
Membranes for Proteins Processing
Joao Crespo 1
1 , FCT-Universidade Nova de Lisboa, Caparica Portugal
Show AbstractThis lecture discusses the development and use of new membranes for the processing of proteins.
Different phenomena and processes will be discussed: protein adsorption and fouling at membrane surfaces; protein permeation through porous media; protein fractionation; and protein crystallization.
The development of membranes with specifically designed topography, and their impact in protein adsorption, will be discussed, as well as the development of membranes that respond to external magnetic field stimuli.
A particular attention will be given to the use of on-line, non-invasive techniques to monitor protein interaction with membranes, namely using on-line fluorescence.
5:00 PM - *SM7.2.06
Bio-Inspired Zwitterionic Membranes for Fouling Resistance
Y. Chang 1
1 R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chungli Taiwan
Show AbstractZwitterionic betaine system has become the new antifouling formulation through the bio-inspired molecular design approaching cell membrane-mimetic nature. Zwitterionic polymeric interface resisting protein adsorption is important in the development of anti-fouling membranes in such applications as membrane bioreactor, wound healing, blood separation filters, antithrombogenic implants, hemodialysis membranes, drug-delivery carriers, and diagnostic biosensors. Previous studies showed that the control of surface charge neutrality is important for a zwitterionic surface with effective protein-resistant properties. Importantly, it was further reported that the pseudozwitterionic (mixed-charge) formulation in self-assembled monolayers, copolymer hydrogels, and polymeric brushes provide a new avenue to achieve nonfouling level surfaces with the prevention of nonspecific biofoulant adsorption if the charge balance can be well controlled.
References:
1) M.C. Sin, S.H. Chen, Y. Chang, Polymer Journal, 46, 436–443 (2014).
2) Y.N. Chou, Y. Chang, T.C. Wen, ACS Appl. Mater. Interfaces, 7, 10096−10107 (2015).
3) A. Venault, K.M. Trinh, Y. Chang, J. Membr. Sci, 501, 68–78 (2016).
5:30 PM - SM7.2.07
The Effect of Dynamic Three-Dimensional Micro-Crack Network Geometry on Water Permeability of the Prickly Pear Cacti Cuticle
Rubin Linder 1 , Kenneth C. Manning 1 , Lucas Majure 2 , Konrad Rykaczewski 1
1 , Arizona State University, Tempe, Arizona, United States, 2 Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, Arizona, United States
Show AbstractCacti thrive in xeric environments through specialized water storage and collection tactics. These plants store water within succulent tissue in their stems and minimize its loss through a small volume to surface ratio and production of a waxy exterior coating that acts as a water permeation barrier.1 In addition, cacti use the Crassulacean acid metabolism, which means that the stomata open during the night to absorb carbon dioxide, but remain shut during the day to reduce evapotranspiration. At that stage the water loss through the closed stomata is comparable to the loss through the outer hydrocarbon barrier.2 In our recent work we demonstrated that prickly pear cacti cuticle develops a network of deep three dimensional micro-cracks in its epicuticular wax throughout a single growth season that dramatically alters the plant’s wetting properties.3 In this work we describe how the three dimensional geometry of these fractures changes with the hydration state of the plant (i.e. large volumetric shrinking and expansion) and the impact of these changes on the moisture transport through the cuticle. Specifically, we quantified the changes in topography of elastomer casts of the micro-fractured cladodes of O. engelmannii var. lindheimeri (Engelmann's prickly pear) at various hydration stages. In turn, we measured the water diffusion coefficient in the extracted wax, which is predominantly composed of alkanes, using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy. Next we substituted the measured value of the diffusion coefficient in un-fractured films and the geometry of the fractured films into Finite Element Method simulations in order to estimate how the hydration state of the plant changes permeation of water through its exterior via micro-fracture shape modulation. Similarly, nano-cracked hydrophobic polymeric membranes have been recently shown to self-regulate their water content and with that provide a significant improvement in electrochemical performance of fuel cells.4 Consequently, our work on self-regulation of cacti cuticle water permeability might provide new insight for biomimetic membrane design.
(1) Anderson, E. F. The Cactus Family; Timber Press: Portland, OR, 2001.
(2) Nobel, P. S. Remarkable Agaves and Cacti.; Oxford University Press: New York, NY, 1994.
(3) Rykaczewski, K.; Jordan, J. S.; Linder, R.; Woods, E. T.; Sun, X.; Kemme, N.; Manning, K. C.; Cherry, B. R.; Yarger, J. L.; Majure, L. C. Microscale Mechanism of Age Dependent Wetting Properties of Prickly Pear Cacti (Opuntia). Langmuir 2016, 32 (36), 9335–9341.
(4) Park, C. H.; Lee, S. Y.; Hwang, D. S.; Shin, D. W.; Cho, D. H.; Lee, K. H.; Kim, T.-W.; Kim, T.-W.; Lee, M.; Kim, D.-S.; et al. Nanocrack-Regulated Self-Humidifying Membranes. Nature 2016, 532 (7600), 480–483.
SM7.3: Poster Session: Membrane Materials for Sustainable Separations
Session Chairs
Mainak Majumder
Suzana Nunes
Kuo Lun (Allan) Tung
Ranil Wrickamasinghe
Wednesday AM, April 19, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - SM7.3.01
Surface Modification on Polymeric Separators Using Silica Coating and Poly(vinylidene fluoride-hexafluoropropylene) Layer for Lithium-Ion Batteries
Chun-Chieh Liao 1 , Chun-Chieh Fu 1 , Chien-Te Hsieh 2 , Ruey-Shin Juang 1 3
1 Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan Taiwan, 2 Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan Taiwan, 3 Department of Nephrology, Chang Gung Memorial Hospital, Linkou Taiwan
Show AbstractIn this study, silica (SiO2) nanoparticles prepared by sol-gel methods were closely coated on the tri-layered microporous PP/PE/PP membrane (Celgard 2320), in which a thin layer of poly(vinylidene fluoride-hexafluoropropylene) was sandwiched as the adhesive agent. Then, such an inorganic-organic composite serves as the separator for lithium-ion batteries (LIBs). Both the improved thermal and dimensional stability can achieve after the deposition of SiO2 in the separators. The improvement is probably due to the formation of robust skeleton to stabilize the separators, imparting a superior insulation and mass transport barrier against volatile compounds formed during thermal decomposition process. Based on an appropriate amount of SiO2 deposits, the SiO2-coated separator still featured a highly porous structure, allowing favorable liquid wettability and high uptake of electrolyte. The amount and size of SiO2 deposits played a vital role in upgrading the cell performance, including high ionic conductivity, low inner resistance, high operation temperature, high energy density, and superior cycleability. Compared to untreated tri-layered separator, for example, the composite separator reveals a higher liquid wettability by 80% and a smaller thermal shrinkage by 100%. As for the LIBs equipped with Li4Ti5O12 anode, the specific capacity using the composite separator coated with 50-nm SiO2 is higher than that with 700-nm SiO2 by 30%.
9:00 PM - SM7.3.02
Janus Carbon Nanotube Membranes Generated by Surface Plasmoxidation and Their Application
Guibin Ma 1 2 , Sinoj Abraham 1 2 , Carlo Montemagno 1 2
1 , Ingenuity Lab, University of Alberta, Edmonton, Alberta, Canada, 2 Department of Chemical & Materials Engineering, University of Alberta, Edmonton, Alberta, Canada
Show AbstractThree-dimensional carbon nanotube network structures with outstanding mechanical and thermal properties membrane mats have generated by surface selective etcher and coating.[1-2] The different types of CNT membranes with both surfaces of either superhydrophobic or superhydrophilic as well as Janus CNT membranes have been successful developed by combination of carbon dioxide (CO2) surface plasmoxidation and thereafter surface silane coating. Variety of these fabricated CNT membranes was fully characterized by SEM, Raman and XPS spectroscopy. The generated superhydrophobic membranes can selectively absorb a wide range of organic molecules or solvents from water. The unique Janus wettability membranes possess the switchable transport performance, and they can effectively be applied to separate both surfactant-stabilized oil-in-water and water-in-oil emulsions. These types of CNT membranes suppose to have great potential applications for oil/water separation. Feasibility studies with emulsions generated from oil sand industries emulsion oil/water separation is under the way. Additional we have found these combination technology can also to apply to other type of nanomaterials, such as metal oxide nanowires to generate the similar properties membranes and wide of application for water purification and oil/water mixture separation.
References
[1] M. F. L. De Volder, S. H. Tawfick, R. H. Baughman, A. J. Hart, Science 2013, 339, 535.
[2] Q. Cao, J. A. Rogers, Adv. Mater. 2009, 21, 29.
9:00 PM - SM7.3.03
In Situ Fe/Pd Nanoparticle Immobilized PVDF Membranes—Synthesis, Depth-Dependent Characterization and Application
Hongyi Wan 1 , Nicolas Briot 1 , Dibakar Bhattacharyya 1
1 , University of Kentucky, Lexington, Kentucky, United States
Show AbstractThe development of functionalized polymeric membranes with catalytic metal nanoparticles provides an effective method of environmental remediation and wastewater treatment. Due to the excellent chemical and mechanical resistance, polyvinylidene fluoride (PVDF) membrane was widely used. With immobilized zero-valent iron (ZVI) or iron-based bimetallic nanoparticles (NPs), functionalized PVDF membranes can be used in chlorinated organic treatment, such as polychlorinated biphenyl (PCB) and trichloroethylene. Poly (acrylic acid) (PAA) was polymerized inside PVDF membrane pores to maximize iron adsorption and prevent aggregation of iron nanoparticles. Furthermore, tunable membrane pore size could be achieved by changing the environmental pH because of ionization of PAA.
Regular preparation techniques of SEM analysis (sectioning, fracturing) usually alter the structure of the region of interest, leading to the characterization of damaged surfaces. Proper observation of the nanoparticles properties, such as size, distribution, density and composition, can only be observed on the surface or external side of the membrane rather than inside the membrane matrix. However, reactivity, antibacterial properties, and membrane hydrophilicity are affected by the properties of nanoparticles beneath the membrane surface. Therefore, focused ion beam (FIB) was used to for cross sectioning of the membrane to prevent mechanical deformation and provide a clean, smooth surface for nanoparticle characterization. Then, the correlation between Fe/Pd nanoparticles properties (size, distribution and density) and the depth within the membrane can be quantified by SEM and TEM. This correlation is important in investigating the reactivity of Fe/Pd immobilized membranes for further degradation simulation.
Based on the results of depth-dependent characterization, nanoparticles size and density were much more uniformly distributed within the membrane rather than on the membrane surface. The nanoparticles size were 19.4±3.2 nm and 16.8±2.6 nm on the membrane surface and under the surface, respectively. Fe/Pd particle regeneration and functionalized membrane reusability in PCB degradation were also studied. In XRD analysis, the Fe/Pd particle samples, which were deliberately oxidized and then reduced, exhibited the same crystalline patterns as the original Fe/Pd particle samples. The membrane maintained reactivity after four PCB degradation cycles with regeneration between each cycle. Furthermore, the Fe/Pd nanoparticle sizes remained relatively stable after four regeneration cycles, changing from 19.4±3.2 nm to 26.8±6.8 nm on the membrane surface. Laminar flow reactor model was applied to investigate reaction rate for convective flow mode experiment and simulate the extent of degradation versus residence time.
This research is supported by the NIEHS-SRP grant P42ES007380, and by the NSF KY EPSCOR program. Full scale PVDF membranes were provided by Nanostone/Sepro (USA).
9:00 PM - SM7.3.04
Fabrication of Graphene Oxide-Supported Metal-Organic Framework Films
Julius Choi 1 , Sergio Capareda 1 , Hae-Kwon Jeong 2
1 Bio-Energy Test and Analysis Laboratory (BETA Lab), Biological and Agricultural Engineering Department, Texas A&M University, College Station, Texas, United States, 2 Artie McFerrin Department of Chemical Engineering and Materials Science and Engineering Program, Texas A&M University, College Station, Texas, United States
Show AbstractGO films exhibit outstanding mechanical strength and possibility as an optimal starting material to make composite films due to the oxygen-containing functional groups. Besides, GO membranes show promising gas separation performance based on interlayer galleries. ZIF-8 membranes show promising gas mixture separation performance by molecular sieves based on microporous structures. Through the application of GO films as a substrate for ZIF-8 films to the fabrication of composite films, enhanced gas separation performance are expected by the integration of properties of each film. Here, we demonstrate the way to fabricate graphene oxide (GO)-supported ZIF-8 films by an in-situ method. The stabilization of GO films is a key step to make well inter-grown ZIF-8 films. Besides, it was found that the kind of used metal ions affects the quality of ZIF-8 films probably due to the affinity of metal ions or exchange of metal ions during reaction. Finally, we demonstrate the binary gases permenace behaviour of this composite films.
9:00 PM - SM7.3.05
Design Motifs in Polyamide Selective Layer Membrane Materials for Improved Chlorine and Fouling Resistant Properties
Logan Kearney 1 , Michael Toomey 1 , Kai Gao 1 , John Howarter 1
1 , Purdue University, West Lafayette, Indiana, United States
Show AbstractIndustrially produced, polyamide based membrane materials are ubiquitously used in high selectivity applications such as reverse osmosis (RO) and nanofiltration (NF). Through years of development and process optimization, the polyamide membrane system is widely and relatively cheaply produced to be used in high performance separations. Unfortunately, the complicated nature of many feed water compositions contribute to the premature loss of performance eventually requiring costly cleaning steps or periodic facility shut down. The primary membrane failure vectors involve the delicate interplay between a diverse set of foulants that accumulate on the upstream membrane surface and chemical disinfectants used to deter their arrangement into films that disrupt the permeation of the intended solvent. In the case of polyamide membrane systems, the use of common halogen based disinfectants (NaOCl) is widely reported to chemically attack the polymer backbone, compromising the selective capabilities of the interface. To address these issues, many research efforts in the field of RO membrane separations have primarily focused on searching for new polymer chemistries that allow for the liberal application of chlorine disinfectants or the addition of functional surface modifiers to reduce surface fouling propensity. In the work presented here, a systematically selected series of moieties will be rapidly assessed with a quartz crystal microbalance in combination with a controlled thin film polymerization technique. The molecular functionalities will be qualified on the basis of chemical stability in halogenated environments, surface wettability and interaction with model foulants. The most promising systems will be integrated into an interfacially polymerized membrane for further characterization in a laboratory RO compatible cross flow cell.
9:00 PM - SM7.3.06
Facile Fabrication of Durable Superhydrophobic Polyurethane Sponge for Continuous Separation of Oil from Water
Xia Zhang 1 , Bei Ding 1 , Meihuan Yao 1 , I.P. Parkin 2
1 National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng China, 2 Department of Chemistry, University College London, London United Kingdom
Show AbstractWith the expansion of oil production and transportation, there is increasing potential for oil spills from industrial accidents or the sinking of oil tankers or ships. Along with the strengthening of environment protection, it becomes a worldwide challenge to solve the frequent oil spill and the increasing amount of industrial oily wastewater and chemical leakage. As a result, there is a need to develop new materials that can effectively separate large amounts oil from water. Superhydrophobic and superoleophilic materials are regarded as promising candidates for the oil/water separation. However, most of the reported superhydrophobic materials are mechanically and chemically unstable. Slight mechanical abrasion will destroy the micro/nanoscale features that give rise to the roughness that are essential for superhydrophobicity. Moreover, mechanical contact may also leave impurities on surfaces, causing a decline in their non-wetting properties. Recently, the bulk material possessing low-surface-energy microstructures extending throughout its whole volume is regarded as a good candidate for designing damage-tolerant superhydrophobicity. When the uppermost layer is removed upon scrape abrasion, the fresh re-entrant surface of the bulk material is also water-repellent, making the superhydrophobicity permanent. Herein, a simple one-step solution immersion method was employed to fabricate the robust superhydrophobic polyurethane sponge by anchoring the hydrophobic SiO2 nanoparticle into the porous bulk polyurethane frame. The durability of the resultant sponge was studied by repeated abrasion test and corrosive liquid attack. After 100 abrasion cycles and strong acid/alkali corrosion, the superhydrophobic polyurethane sponge still shows good repellence to water. Importantly, through a conjunction with the vacuum system, the obtained polyurethane sponge could be used for continuous separation of oil pollutants from the water surface quickly and effectively, making it a promising candidate material for use in oil-spill cleanups.
9:00 PM - SM7.3.07
Characteristics of the Ultrafiltration Membranes Assembled with Zinc Oxide Nanoparticles onto the Surface of Polyethersulfone and Aminated Polyethersulfone Blend
Hyejin Park 1 , So-Hyeon Hong 1 , Eun yeob Choi 1 , Chang Keun Kim 1
1 , Chung-Ang University, Seoul Korea (the Republic of)
Show AbstractUltrafiltration membranes composed of polyethersulfone (PES) and aminated PES (PES-NH2) were fabricated using a non-solvent-induced phase separation process, and then zinc oxide (ZnO) nanoparticles were assembled onto the membrane surface. To assemble ZnO nanoparticles onto the PES/PESNH2 membrane surface, thionyl chloride-terminated ZnO nanoparticles were reacted with the amine groups in PES-NH2. The formation of PES-NH2 and PES/PES-NH2 membranes assembled with ZnO nanoparticles was confirmed using FT-IR, XPS, FE-SEM, and EDS analyses. The hydrophilicity and water flux of the membranes increased with increasing PES-NH2 content. No antibacterial activity was observed for PES/PES-NH2 membranes, while PES/PES-NH2 membranes assembled with at least 0.8 wt%
ZnO nanoparticles displayed antibacterial activity (= 6.1). Membranes having antibacterial activity, high water flux, and improved fouling resistance without a loss in solute rejection were fabricated by assembling ZnO nanoparticles onto the PES/PES-NH2 membrane surface.
9:00 PM - SM7.3.08
Gel Electrolyte Based on Functionalized Bacterial Cellulose Membrane for Batteries
Nazifah Islam 1 , Guofeng Ren 1 , Zhaoyang Fan 1
1 Electrical & Computer Engineering, Texas Tech University, Lubbock, Texas, United States
Show AbstractBacterial cellulose (BC) membranes, produced in an environmentally friendly microbial fermentation process, have unique physical and chemical properties, suitable for many applications. Here we report the study of using functionalized BC membrane as framework to form gel electrolyte used in batteries, in substitution of the liquid electrolyte and polymer separator. BC aerogel membrane is comprised of branched nanoribbons like a spider web but in three dimension. Unlike plants cellulose, BC has high purity and crystallinity with strong mechanical strength and thermal endurance. Its 3D porous structure with large porosity can hold a large amount of electrolyte to form gel. This novel gel electrolyte was found to be capable of providing manifold advantages over existing electrolyte/separator assemblies. It manifests high ionic conductivity, comparable with their liquid counterpart and unlike other solid electrolytes, ensures excellent interface at both anode and cathode. Moreover, it reduces the potential risk posed by liquid electrolytes that may be caused by chemical instability at certain conditions and leakage. Functionalized with oxide nanoparticles further enhance the mechanical and thermal properties. In this work, fabrication and characterization of BC-based gel electrolyte and its performance in rechargeable batteries will be reported, and particular emphasis will be given on the comparison to the conventional polymer separator and liquid electrolyte.
9:00 PM - SM7.3.09
Oxygen Selective Membrane for Lithium Air Batteries
Lujie Cao 1 , Minchan Li 1 , Ying Liu 1 , Wenxi Wang 1 , Zhouguang Lu 1
1 , South University of Science and Technology of China, Shenzhen China
Show AbstractLithium air batteries have attracted great recent research interest due to their much higher energy density than that of the currently used Li-ion batteries (3600 Wh kg-1 vs 300 Wh kg-1). However, one of the most critical issues for practical application of Li-air batteries was the contamination of moisture and CO2 from the air. Here we report a high performance O2 selective mixed matrix membrane based on the metal organic framework (MOF) nanocrystallines of CAU-1-NH2@PDA (CAU = Christian-Albrechts-University) and the polymer of polymethylmethacrylate (PMMA). CAU-1-NH2 is a stable metal–organic framework [Al4(OH)2-(OCH3)4(H2N-bdc)3]xH2O, containing the new Al-containing octameric brick {Al8(OH)4(OCH3)8}12+ (Fig. 1). It has been found that the obtained mixed matrix membrane (MMM) possessed several advantages including high surface area, controlled porosity, adjustable chemical functionality, high affinity for specific gases and compatibility with polymer chains, making it attractive candidate for selective gas separation. Specifically, the functional group –NH2 in the MOF, –OH in the polydopamine molecule, and the –C=O in the PMMA would preferably interact with CO2 molecule. Also, the intrinsic hydrophobic behaviour of the PMMA polymer can favourably prevent the intrusion of moisture (Fig. 1). These two favourable effects guaranteed the Li-air cell working very stable under ambient atmosphere with very high relative humid (30%) by repelling CO2 and moisture from the air. Evidently, the developed mixed matrix membrane based on CAU-1-NH2@PDA and PMMA polymer opens the way to develop novel air-permeable membrane for real Li-air batteries applied in ambient conditions rather than in pure oxygen (Li-O2) conditions.
References
Cao, L.J.; Lv, F.C.; Liu, Y.; Wang, W.X.; Huo, Y.F.; Fu, X.Z.; Sun, R.; Lu, Z.G. Chem. Commun. 2015, 51, 4364;
Li, F.; Zhang, T.; Zhou, H. S. Energy Environ. Sci. 2013, 6, 1125.
Lu, J.; Li, L.; Park, J.B.; Sun, Y.K.; Wu, F.; Amine, K. Chem. Rev. 2014, 140411104032007.
Liu, Y.; Cao, L.J.; Cao, C.W.; Wang, M.; Leung, K.L.; Zeng, S.S.; Hung, T.F.; Chung, C.Y.; Lu, Z.G. Chem. Commun. 2014, 50, 14635.
Cao, L.J.; Tao, K.; Huang, A.; Kong, C.; Chen, L. Chem. Commun. 2013, 49, 8513.
Lee, H.; Dellatore, S. M.; Miller, W. M.; Messersmith, P.B. Science, 2007, 318, 426.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (No. 21671096 and 21603094), the Shenzhen Peacock Plan (No. KQCX20140522150815065), the Natural Science Foundation of Shenzhen (No. JCYJ20150630145302231, JCYJ20150331101823677), the Starting-Up Funds of Southern University of Science and Technology (SUSTech) through the talent plan of the Shenzhen Government, and the Science and Technology Innovation Foundation for the Undergraduates of SUSTech (2015x19 and 2015x12).
9:00 PM - SM7.3.11
Surface Modification of Microfiltration Ceramic Membrane by Using Laser Induced Graphene (LIG)
Mohamed Bayati 1 , Haiming Peng 1 , Heng Deng 2 , Jian Lin 2 , Maria Fidalgo de Cortalezzi 1
1 Civil/Environmental Engineering, University of Missouri, Columbia, Missouri, United States, 2 Mechanical & Aerospace Engineering, University of Missouri, Columbia, Missouri, United States
Show AbstractMembrane-based technology has been widely applied to different fields, from water treatment, food industry, to pharmaceutical manufacturing . In this study, a novel technique has been used to fabricate a uniform, stable, and strongly bonded graphene layer on a microporous ceramic membrane acting as support material. A composite ceramic-LIG membrane was fabricated using one step scalable way. The ceramic support was spin-coated with a 12.0 wt % solution of poly (pyromellitic dianhydrideco-4,4-oxidianiline, amic acid) (PAA) and transformed to polyimide (PI) by thermal imidization. The PI was then irradiated using H-series Desktop CO2 laser to photothermally convert the sp3-carbon atoms to sp2-carbon atoms. The laser was operated at 10 W power, 24 inch.s-1 raster speed, and 1000X1000 dpi raster mode.
The LIG layer was characterized by SEM, FTIR, BET, XRD, and contact angle measurements. Water flux and the rejection characteristics of the LIG-ceramic composite membrane was further investigated, as they are main aspects governing the membrane performance, by clean water and colloidal silica (SNOTEX ST-30-L, ST-O, and ST-ZL, Nissan Chemicals) filtrations. FTIR results showed a complete conversion of PAA to PI using thermal imidization. The XRD results showed an intense peak at 2θ = 25.9o, which gives an interlayer spacing of 3.4 Å between (002) planes in the LIG, indicating a high degree of graphitization. Another peak at 2θ = 42.9o indicates (100) reflections which are associated with an in-plane structure. The BET analysis showed a surface area of 130 ± 5.6 m2/g. The permeability of uncoated ceramic membrane decreased from 2360 L/h.m2.bar to 1400 L/h.m2.bar using one layer coating.
The new composite membrane is a promising new material for membrane distillation or electro osmosis, where the hydrophobicity and electrical conductivity of the graphene layer may provide important advantages over current membrane materials.
9:00 PM - SM7.3.12
Characteristics of Ultrafiltration Membranes Fabricated from the Composites Polyethersulfone and Polyethersulfone Grafted with Multi-Walled Carbon Nanotube
So-Hyeon Hong 1 , Hyejin Park 1 , Eun yeob Choi 1 , Chang Keun Kim 1
1 , Chung-Ang University, Seoul Korea (the Republic of)
Show AbstractA novel ulftrafiltration membranes composed of polyethersulfone (PES) and PES grafted with multi-walled carbon nanotube (PES-MWCNT) by a non-solvent induced phase separation process. The MWCNTs functionalized with organics containing amine end groups were reacted with PES functionalized with sulfonyl groups to prepare PES-MWCNT. Formation of the amine terminated MWCNTs, PES functionalized with sulfonyl groups, and PES-MWCNT was confirmed using FT-IR, XPS, FE-SEM, 1H-NMR, and EDS analyses. The hydrophilicity of the fabricated membranes increased with increasing PES-MWCNT content in the membrane. No antibacterial activity was detected in the PES membrane, but PES membranes containing PES-MWCNT exhibited antibacterial activity. The water flux and the antibacterial activity of PES/PES-MWCNT membranes increased with increasing PES-MWCNT content. PES/PES-MWCNT membranes exhibited the same solute rejection with PES membrane regardless of PES-MWCNT content. As a result, membranes exhibiting high water flux and antibacterial activity without a loss in solute rejection could be produced by adding PES-MWCNT to PES.
9:00 PM - SM7.3.13
Highly Porous Hierarchical Carbons by Activation of Organo-Nitridic Polymers for Carbon Dioxide and Methane Storage
Babak Ashourirad 1 , Katie Cychosz 2 , Matthias Thommes 2 , Hani El-Kaderi 1
1 , Virginia Commonwealth University, Richmond, Virginia, United States, 2 , Quantachrome Instrument, Boynton Beach, Florida, United States
Show AbstractA series of highly porous carbon materials have been successfully fabricated by activation of organo-nitridic covalent frameworks as easily scalable single-source precursor. We deliberately selected a porous organic polymer with a phosphazene core to generate more porosity by evolution of volatile species during activation/carbonization process. The chemical activation under mild sheer ratio of activation agent to precursor (KOH/polymer = 2) and temperature range (500-800 °C) resulted in development of various porous structures ranging from pure microporous to hierarchical of micro-mesoporous frameworks. In particular, high temperature activated carbon features exceptionally high surface area and pore volume of 4000 m2 g-1 and 2.5 cm3 g-1, respectively. A considerable amount of doped elements and micropores are mainly retained for carbons synthesized at lower temperatures whereas higher temperatures resulted in formation of narrow mesopores domains and large pore volumes. Our results showed that samples with higher level of narrow micropores show higher gas uptake at relatively low pressure (below 10 bar), while wider micropores or micro/meso hierarchy of pores lead to higher gas uptake at higher pressures. The highest surface excess uptakes were found to be around 15 mmol g-1 (at 298 K / 65 bar) and 25 mmol g-1 (at 298 K / 30 bar) for CH4 and CO2, respectively.
Symposium Organizers
Suzana Nunes, King Abdullah University of Science and Technology (KAUST)
Mainak Majumder, Monash University
Kuo Lun (Allan) Tung, NTU Taiwan
Ranil Wrickamasinghe, University of Arkansas
SM7.4: Stimuli-Responsive Membranes
Session Chairs
Thomas Schafer
Ranil Wrickamasinghe
Wednesday AM, April 19, 2017
PCC North, 100 Level, Room 123
9:00 AM - *SM7.4.01
Novel Polytriazole Ion Exchange Membranes for Bioseparations
Cristiana Boi 2 , Stefan Chisca 1 , Monica Torsello 2 , Marco Avanzato 2 , Suzana Nunes 1
2 DICAM, University of Bologna, Bologna, Choose a State or Province, Italy, 1 Biological and Environmental Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal Saudi Arabia
Show AbstractThere is a need for processes of membrane manufacture using solvents, which are not associated with hazards, which would be safer and greener than those used so far in industrial processes. Ionic liquids (IL) and dimethyl carbonate (DMC) are considered environmentally friendly solvents, because are non-toxic, relatively inert and safe under ambient conditions.
This work presents a new green process for manufacture of polytriazole ion exchange membranes for protein separation. This involves the solubilization at room temperature of a polytriazole with free OH groups in ionic liquids such as, 1-ethyl-3-methylimidazolium acetate (IL) and dimethyl carbonate (DMC). The interesting fact is that the polytriazole polymer is not soluble in pure IL or DMC, but it is soluble in different ratios mixture of these two solvents. We experimentally evaluated the solvent ratios leading to one phase solution, delimitating the phase diagram for this system. The membranes were obtained by phase inversion, using water as precipitation bath or mixture of water – methanol and water – ethanol. We studied by SEM how the ratio of the solvents and how different precipitation baths influence the membrane morphology. The membranes were activated for lysozyme adsorption by grafting sulfonic groups. Two sultone structures were used as grafting agents: 1,3 propane sultone and 1,4-butane sultone. The modification of the membranes took place by ring opening mechanism. The activation was done by immersion in 5%wt solution of grafting agent in water, containing small amount of NaOH, at 65 °C. The grafting sulfone groups on the membrane were confirmed by FTIR, NMR and TGA, and the membranes morphology was investigated by SEM.
The ion-exchange membranes were preliminary characterized in bind and elute mode using pure lysozyme solutions. The Tris buffer, chosen for equilibration and adsorption, was optimized in terms of molarity and pH. The membranes modified with 1,4-butane sultone showed higher adsorption than the membranes modified with 1,3-propane sultone. Indeed, the values of static binding capacity obtained are promising and comparable to that of commercial ion-exchange membrane adsorbers used for polishing steps in antibody manufacturing.
9:30 AM - *SM7.4.02
High Performance or Stimuli-Responsive Polymer-Based Ultrafiltration Membranes by Phase Separation Processes Using Tailored Macromolecular or Nanoparticular Additives
Mathias Ulbricht 1 , Xi Lin 1 , Jens Meyer 1 , Janina Zwartscholten 1
1 , University of Duisburg-Essen, Essen Germany
Show AbstractMost synthetic membranes are made from polymers because barrier and surface properties can be varied in wide ranges with help of established scalable manufacturing processes. Significant efforts are devoted to improve membrane performance with respect to high selectivity, high flux and additional features. Here we present two approaches to change properties of porous membranes made from established polymers by integrating tailored functional additives in the standard membrane fabrication process, i.e. non-solvent induced phase separation (NIPS). In the first approach, separation performance of ultrafiltration (UF) membranes from polyvinylidene fluoride (PVDF) is improved by adding poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA). In solvents used for membrane casting, copolymer micelles can be induced by complexing the PEO block with specific metal salts. Using the same combinations of PEO-b-PMMA and salt in solutions of PVDF, UF membranes with higher surface porosity and more regular barrier pore structure are obtained through microphase separation during the NIPS process. It is possible to tailor molecular weight cut-off (MWCO) between 30 kDa and 110 kDa by varying type and amount of salt in otherwise identical casting solutions. The permeability of thus obtained membranes is significantly higher than for comparable conventional PVDF membranes. We also explore how a larger tendency toward microphase segregation in analogous PEO-based diblock copolymers, i.e. those with poly(isopropyl methacrylate) and poly(tert.-butyl methacrylate) blocks, can be used to obtain isoporous UF membranes. The second approach focuses on novel magneto-responsive UF membranes where “remote control” stimulation by high frequency alternating magnetic field (AMF) leads to large and reversible changes of macromolecule sieving [1]. We use polyethersulfone (PES) as porous membrane matrix material, poly(N-isopropylacrylamide) (PNIPAAm) microgel (MG) particles as thermo-responsive actuator and iron oxide nanoparticles (IONP) as local “nanoheaters” to be triggered by AMF. Mixed matrix composite membranes are obtained via synergistic co-assembly of the three components during NIPS of a solution/dispersion of PES, PNIPAAm MG and IONP in NMP with water as coagulation bath. Performance of the novel membrane can be controlled by the swollen/shrunken state of PNIPAAm MG embedded in the nanoporous barrier layer of a PES-based anisotropic porous matrix via heat generation of nearby MNP. One prototype has a permeability of ~80 L/m2hbar and a MWCO of ~70 kDa at room temperature/without AMF. Flux increases by a factor of 10 and MWCO changes to >1500 kDa upon switching on AMF; this response is fully reversible. Such membrane has potential as enabling material for remote controlled drug release systems or devices for tunable fractionations of biomacromolecule mixtures.
[1] X. Lin, B. N. Quoc, M. Ulbricht, ACS Appl. Mater. Interf. 2016, doi: 10.1021/acsami.6b09369.
10:00 AM - *SM7.4.03
In Situ Silver Nanoparticle Coating onto MF, UF and RO Membranes for Biofouling Control—A Bench and Testbed Water Permeability Study
Shahnawaz Sinha 1 , Sean Zimmerman 1 , Francois Perrault 1 , Paul Westerhoff 1
1 , Arizona State University, Tempe, Arizona, United States
Show AbstractBiofouling remains one of the greatest challenges to the water industry to date. Among the many strategies practiced by the water industry, an effective pretreatment system with proper disinfection practices with cleaning protocol remains the only viable option. Although it is widely practiced, it seems not to be fully effective in eliminating biofouling altogether. Other options include the use of biocides, antifoulant agents, or other specialty chemicals addition in conjunction with above practices, resulting in higher operating costs but with a similar outcome. The use of new generation antifoulant membranes (e.g., with various polymer chemistries, functionalization, surface modification and/or composite materials, etc.) remains in the early stages of development toward commercial application. In the recent years, application of silver nanoparticles (NPs) with antibacterial activities is found to be effective in controlling biofouling but limited due to higher operating costs and/or safety related issues (e.g., NPs release) for its full-scale application. Alternative to this approach would be to add silver NPs during membrane fabrication process. However, this will require a new manufacturing process altogether and can also lead to lower biocidal efficiency. The lower potency is due to most of the silver NPs being embedded within the polymer matrix as opposed to the membrane surfaces, losing its overall effectiveness. An alternative to this approach would be to maintain a thin layer of silver NPs on the top of the membrane surfaces. This method is in-situ, with a short reaction time, utilizing the existing membranes without requiring a new fabrication process. As the NPs are bonded tightly to the membrane surfaces, there is a minimal loss or release of NPs expected to the environment. Overall it may provide a more practical way of addressing the current biofouling issue with the possibility of full-scale application, assessed as part of this study. The method was developed at Yale University, one of the four participating universities to the recently NSF funded Nano-Enabled Water Treatment (NEWT) Center. The process is further assessed at Arizona State University, a partnering university, at both bench and NEWT-Mobile (testbed), utilizing MF, UF and RO membranes in flat-sheet and spiral-wound operations, respectively. One of the primary objectives of the NEWT center is to develop next-generation, affordable, mobile, modular, high-performance water treatment systems enabled by nanotechnology. Membrane properties, NPs loading rate, NPs dissolution, antimicrobial activity, and membrane permeability changes due to the coating were monitored. Membrane surface properties were also characterized in terms of surface charge and hydrophilicity to provide greater insights due to the modification process. This paper will present these results and application of silver NPs on biofouling control with water permeability in benefiting the water industry.
10:30 AM - *SM7.4.04
DNA-Sandwich Gated Membranes
Thomas Schafer 1 2 , M. Ali Aboudzadeh 1
1 , Polymat University of the Basque Country, San Sebastián Spain, 2 , Ikerbasque - Basque Foundation for Science, Bilbao Spain
Show AbstractStimulus-responsive membranes have been explored for decades for liquid separations or controlled release applications yielding materials whose permeability varies based on a bulk stimulus such as, for example, pH, temperature, or ionic strength. Triggering a change in permeability through a specific target-receptor interaction and a locally acting molecular recognition mechanism as found in nature, however, remains a challenge. Here we report on one such approach consisting of self-assembled DNA sandwich structures which are integrated into nanoporous membrane supports. The resulting gating membranes are responsive to a molecular recognition event, rather than to common bulk stimuli, and specifically respond to adenosine-triphosphate (ATP).
Controlled assembly and stimulus-responsiveness of the DNA-sandwich structures were monitored and characterized by multi-parameter surface plasmon resonance (MP-SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D). Responsiveness and mass transport across the DNA-sandwich gated membranes were then investigated using a thermostated permeation cell.
The DNA-sandwich structures developed were detected by MP-SPR as a mass and thickness increase on the sensor surface, while their viscoelasticity was furthermore quantified by QCM-D. Upon integration into the nanoporous membranes, pore blocking was achieved while upon exposure of the DNA-multilayer to the target (ATP) a complete rupture was brought about, resulting in pore opening.
Potential applications of the developed networks are modulating diffusive flow across membrane pores and also creating sensitive nanoparticle assemblies for controlled drug delivery.
11:30 AM - SM7.4.05
Magnetically Responsive Membranes
Ranil Wrickamasinghe 1 , Xianghong Qian 1
1 , University of Arkansas, Fayetteville, Arkansas, United States
Show AbstractBiological membrane can adjust their barrier properties based be on external environmental stimuli. In recent years there has been tremendous interest in developing synthetic membranes that can also respond to external environmental stimuli. We have developed a range of magnetically responsive membranes. These membranes display changes in their barrier properties when subjected to an external magnetic field. Microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF) membranes have been modified by grafting polymer brushes from the membrane surface. Atom transfer radical polymerization (ATRP) has been used to graft two polymer: poly-hydroxyethyl methacrylate (PHEMA) and poly(N-isopropylacrylamide) (PNIPAm) from the surface of the membranes. PHEMA is very flexible while PNIPAm exhibits a lower critical solution temperature (LCST) at about 32 °C in DI water. Superparamagnetic nanoparticles were attached to the chain ends. In an oscillating magnetic field interactions between the external magnetic field and the magnetic moment of the nanoparticles will lead to heat generation as well as movement of the nanoparticles. Movement can be optimized my carefully selecting the oscillation frequency of the external field.
We show that for MF and NF membranes we can induce movement of the PHEMA brushes in an oscillating magnetic field. For membranes grafted with PNIPAm, we show that heating due to interaction of the oscillating magnetic field with the attached superparamagnetic particles can lead to collapse of the grafted chains most likely due to the temperature of the actual polymer chains being higher than the LCST. Both effects lead to significant change in membrane rejection and flux. In the case of NF membrane changes in membrane performance are due to polymer chains grafted from the barrier surface of membrane while for MF membranes, changes in performance are due to the chains grafted from the internal pore surface.
We have also modified UF membranes. We have developed a method to selectively graft PHEMA from the internal membrane pore surface or from the outer membrane surface. The method depends upon using an activator generated by electron transfer (AGET) ATRP procedure and limiting the ATRP initiator to the membrane pore or outer surface. Attachment of superparamagnetic nanoparticles to the polymer chains on the membrane surface can lead to a decrease in concentration polarization during protein filtration. On the other hand for membranes with nanoparticles attached inside the pores we can change membrane rejection in the presence of an external magnetic field.
Using PHEMA and PNIPAm as model polymers, we show how movement and heating induced by the attached nanoparticles can lead to changes in polymer conformation. We show that for NF, UF and MF membranes these changes in polymer conformation maybe used to tune membrane performance.
11:45 AM - SM7.4.06
Stimuli-Responsive Smart Gating Membranes
Liang-Yin Chu 1
1 , Sichuan University, Chengdu China
Show AbstractMembranes are playing paramount roles for sustainable development in myriad aspects such as energy, environments, resources and human health. However, the unalterable pore size and surface property of traditional porous membranes restrict their efficient applications. The performances of traditional membranes will be weakened upon the unavoidable membrane fouling, and they cannot be applied to the cases where self-regulated permeability and selectivity are required. Inspired by the natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart gating membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous membranes to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technology. The smart gating membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via flexible adjustment of pore sizes and surface properties based on the "open/close" switch of the smart gates in response to environmental stimuli.[1–3] This presentation introduces the recent development of stimuli-responsive smart gating membranes, including the design strategies and the fabrication strategies that based on introduction of the stimuli-responsive gates after or during membrane formation, the positively and negatively responsive gating models of versatile stimuli-responsive smart gating membranes, as well as the advanced applications of smart gating membranes for regulating substance concentration in reactors, controlling release rate of drugs, separating actives based on size or affinity, and self-cleaning of membrane surfaces. With self-regulated membrane performances, the smart gating membranes show great power for global sustainable development.
References
[1] L.Y. Chu, Smart Membrane Materials and Systems, Springer-Verlag, Berlin (2011).
[2] L.Y. Chu, R. Xie, X.J. Ju, Chin. J. Chem. Eng., 19, 891-903 (2011).
[3] Z. Liu, W. Wang, R. Xie, X.J. Ju, L.Y. Chu, Chem. Soc. Rev., 45, 460-475 (2016).
12:15 PM - SM7.4.08
Diazonium-Functionalized Nanoporous Membranes for Electrochemically Switchable Ionic Separations
Leo Small 1 , David Wheeler 1 , Erik Spoerke 1
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractIonic transport through nanoporous membranes is regulated in a large part by the surface charge on the nanopore walls. The ability to control this parameter in-situ provides a way to tune membrane systems in real time. Diazonium chemistries provide a convenient route to functionalization of complex surfaces by redox-active molecules, whereby the surface charge may be altered by changing the oxidation state of the molecule. Here we demonstrate successful functionalization of high-density, ion-tracked, gold-plated nanoporous polycarbonate membranes by several diazonium salts featuring redox-active nitrophenyl, quinone, or trimethyl lock chemistries. The influence of surface functionalization and redox state on selective ion transport through these functionalized nanoporous membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. By incorporating chemistries which involve a chemical and an electron transfer event, the charge state of the nanopore surface is stabilized, obviating the need for a continuously applied gate voltage to retain ionic transport properties. These stable, switchable chemistries facilitate superior control of molecular transport across the membrane, enabling tunable ion transport systems.
Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
12:30 PM - *SM7.4.09
Simulations of Responsive Polymers for Membrane Applications
Xianghong Qian 1
1 , University of Arkansas, Fayetteville, Arkansas, United States
Show AbstractTailored responsive membranes have wide applications in many industrial processes including water recycle and reuse, purification of chemicals and pharmaceuticals, and bioseparations. Thermo-responsive polymers such as poly (N-isopropylacrylamide) (PNIPAM) and poly (vinylcaprolactam) (PVCL) change their conformations in response to environmental stimuli such as temperature and ionic strength. Surface modification of PNIPAM and PVCL on ultrafiltration membranes has been explored for pore-size control and for developing hydrophobic interaction chromatography. Classical molecular dynamics (MD) simulations were conduced to investigate the effects of salt ions on the low critical solution temperature of PNIPAM and PVCL. Specificity in cation-polymer interactions is elucidated. Moreover, insights on ion-specific hydration and dehydration effects are obtained.
Designing polymer surfaces that are non-fouling has been a central issue in membrane research. Grafting is frequently used for membrane surface modification to reduce fouling. Surface modifications with ionic strength responsive zwitterionic materials have been found to be effective in resisting protein attachment. Combined quantum mechanical and classical mechanical calculations were conducted to investigate the hydration properties of carboxybetaine zwitterion trimmers with varying separation distances between the quaternary ammonium cation and carboxylic anion. The competition between the strong hydration force of charged groups and the dehydration force of the hydrocarbon chains leads to the nanoscale-dewetting effect. This has significant implications for developing fouling resistance polymers and surfaces.
SM7.5: Nanostructured Polymeric Membranes
Session Chairs
Ayse Asatekin
Darrell Patterson
Wednesday PM, April 19, 2017
PCC North, 100 Level, Room 123
2:30 PM - *SM7.5.01
Manufacturing Functional Membranes from Nanostructured Polymers
William Phillip 1
1 , University of Notre Dame, Notre Dame, Indiana, United States
Show AbstractThe majority of state-of-the-art membranes utilize a size-selective, steric exclusion mechanism to sort dissolved solutes from solution. In this regard, self-assembled block polymers are a promising platform for producing high-performance, next-generation membranes because large areas of membranes that contain a high density of well-defined nanoscale pores can be produced readily from these novel macromolecules using the self-assembly and non-solvent induced phase separation (SNIPS) technique. This membrane fabrication technique is consistent with the roll-to-roll processes used to fabricate existing commercial membranes. Furthermore, the performance profile of the block polymer membranes can be controlled through clever design of the macromolecular precursors. These membranes and others with comparable nanostructures are pushing the limits of size-selective separation mechanisms. As such, there is a growing interest in chemically-selective membranes that allow for efficient, high throughput separations based on chemical factors. In this work, we discuss a block-polymer-derived membrane platform that can be post-synthetically modified, in a facile and scalable manner, to the specific needs of a multitude of processes. Specifically, the SNIPS technique is used to transform the triblock polymer polyisoprene-b-polystyrene-b-poly(N,N-dimethyacrylamide) (PI-PS-PDMA) into membranes with nanoscale pores that are lined by poly(N,N-dimethylacrylamide) moieties. The PDMA groups that line the pore walls are converted by simple hydrolysis to polyacrylic acid (PAA) groups, which can be easily reacted to other functionalities that are molecularly-designed for target applications. In one example, the pore-lining groups are converted to N-(2-ethanethiol) polyacrylamide (PASH) moieties that act as high capacity binding sites for heavy metal ion adsorption. When placed in a solution containing lead (II) ions, this PASH-functionalized membrane is able to remove over 99% of the heavy metal content from solution. In another example, charge mosaic membranes, which have distinct anionic and cationic domains that traverse the membrane thickness are prepared by functionalizing the copolymer membrane precursors using ink-jet printing devices. The well-defined counter-charged domains that cover the surface of the charge mosaic membrane allows dissolved salts to permeate more rapidly than water, even though water is three times smaller in size. As such, charge mosaic membranes can be utilized in a variety of applications that require the selective permeation of ionic solutes. Through these examples, we will demonstrate that membranes that are based on self-assembled block polymer materials provide a scalable and efficient platform that can be tailored to myriad chemically-selective separations in future applications.
3:00 PM - SM7.5.02
Triblock Terpolymer Derived Isoporous Ultrafiltration Membranes
Yuk Mun Li 1 , Divya Srinivasan 1 , Parth Vaidya 1 , Ulrich Wiesner 1
1 , Cornell University, Ithaca, New York, United States
Show AbstractBlock copolymer derived nanostructured materials provide a unique platform for novel membranes used for engineering applications such as water filtration, separation of biomaterials, and drug delivery. A particularly interesting approach that has received increasing attention in the last couple of years is the formation of isoporous ultrafiltration membranes via the combination of block copolymer self-assembly (SA) with non-solvent induced phase separation (NIPS), a process now referred to as SNIPS. We have investigated triblock terpolymer based NIPS membranes as a result of their improved mechanical properties over the corresponding diblock copolymer derived membranes. In this talk after introduction of the NIPS process and the associated molecular engineering of membrane properties via variation of polymer molecular architecture, new insights into the fabrication of asymmetric membranes from two chemically distinct triblock terpolymers via blending during the standard membrane process are provided. Resulting membranes open a new direction for membrane fabrication through the use of mixtures of chemically distinct block copolymers enabling the tailoring of membrane surface chemistries and functionalities.
Li, Y. M., Srinivasan, D., Vaidya, P., Gu, Y., & Wiesner, U. (2016). Asymmetric Membranes from Two Chemically Distinct Triblock Terpolymers Blended during Standard Membrane Fabrication. Macromolecular Rapid Communications, 37(20), 1689-1693.
3:15 PM - SM7.5.03
Cyclodextrin Films with Fast Solvent Transport and Shape-Selective Rejection
Luis Francisco Villalobos 1 , Klaus-Viktor Peinemann 1
1 , KAUST, Thuwal Saudi Arabia
Show AbstractEnergy-efficient separations require highly permeable and selective membranes with a sharp cut-off in a targeted size-range. The performance—when dealing with small molecules (< 2nm)—is determined by the free-volume and nature of the membrane material. However, controlling the free-volume in polymeric materials remains a challenge. Ideally, it should be permanent, interconnected and have a narrow aperture-size distribution. Here, we report the molecular-level design of a new type of filtration membranes made of crosslinked cyclodextrins—intrinsically porous molecules. Numerous paths with defined apertures are generated through the separation layer (i.e. free volume) thanks to their channel-like cavity.
The preparation of cyclodextrin-based crosslinked polymers has been known for more than 50 years. Surprisingly, the fabrication of a membrane made entirely of cyclodextrins remained elusive. For the first time, we will present a scheme to fabricate continuous films made exclusively of crosslinked cyclodextrins—inexpensive macrocycles of glucose, shaped like a hollow truncated cone.
The presence of hydrophobic (cavity) and hydrophilic (ester-crosslinked outer part) domains in the nanofilms results in exceptionally high permeances for both polar and non-polar solvents. The measured fluxes are at least an order of magnitude higher than commercially available membranes. In addition, the transport of molecules through cyclodextrin membranes is highly shape-sensitive.
4:30 PM - *SM7.5.04
Recent Advances in the Design of Nanoporous, Ionic Lyotropic Liquid Crystal Polymer Membranes for Molecular Size Separations in Water
Douglas Gin 1 , Sarah Dischinger 1 , Richard Noble 1
1 Department of Chemistry & Biochemistry, and Department of Chemical & Biological Engineering, University of Colorado, Boulder, Colorado, United States
Show AbstractCross-linked ionic lyotropic (i.e., surfactant) liquid crystal (LLC) assemblies with uniform, charged pores in the 0.7–1.0 nm range can be used as a new type of polymer membrane material for molecular size separations in water. Notably, we found that ordered, 3D-nanoporous LLC networks with a type I bicontinuous cubic (QI) phase can be prepared from an imidazolium bromide-based gemini LLC monomer blended with glycerol. These QI assemblies can be readily processed and polymerized into supported thin-film composite (TFC) membranes that have cationic 0.96-nm-wide annular pores with the bromide counterions as a mobile species inside the pores. The resulting TFC membranes are able to exclude dissolved molecular solutes from water via molecular sieving and charge repulsion effects in the pores. Herein, we show that the effective nanopore size and non-charged solute rejection characteristics of these TFC QI LLC polymer membranes can be altered by postpolymerizaton exchange of the original bromide ions in the pores with different size anions. The relative merits and technical challenges of this approach to polymeric membrane nanopore size and solute selectivity control will be discussed.
5:00 PM - *SM7.5.05
Zwitterionic Copolymers for Next-Generation Membranes
Ayse Asatekin 1
1 , Tufts University, Medford, Massachusetts, United States
Show AbstractZwitterions, defined as functional groups with equal numbers of positive and negative electrostatic charges, strongly resist biomacromolecular adsorption due to their high degree of hydration. This has led to their incorporation into membranes to prevent fouling by various methods, especially by surface functionalization of existing membranes. Zwitterions also have interesting self-assembly capabilities due to their high dipole moments and strong intra- and inter-molecular interactions. They also interact with small ions and exhibit ionic strength response. Our group aims to better understand how zwitterion-containing copolymers self-assemble, and utilize their behavior to develop membranes with improved capabilities: controlled, monodisperse pore size, high flux, fouling resistance, and scalable manufacture.
Random copolymers of zwitterionic and hydrophobic monomers self-assemble into ~1 nm interconnected domains. This makes them excellent candidates for membrane selective layers with high flux, fouling resistance, size selectivity, and chemical resistance. Composite membranes made by coating these copolymers onto commercial ultrafiltration membrane supports exhibit fluxes as high as 21 L/m2.h.bar. Based on the rejection of anionic and neutral dyes of varying sizes, they show size-based selectivity with a cut-off around 1 nm. This pore size closely matches the size of the zwitterionic nanochannels. These membranes also exhibit excellent fouling resistance, showing little to no flux decline and essentially complete flux recovery with a water rinse upon the filtration of foulants such as protein solutions and oil suspensions. Well-designed membranes show no flux decline even in week-long fouling experiments with oil suspensions. These are the first examples of membranes that gain their selectivity from the microphase separation of zwitterionic groups in addition to their fouling resistance.
Zwitterion-containing polymers can also be blended with a commodity polymer such as polyvinylidene fluoride (PVDF) during membrane manufacture by non-solvent induced phase inversion to prevent fouling. Studies demonstrate varying degrees of fouling resistance when zwitterion-containing amphiphilic copolymers are blended with PVDF to prepare membranes, but we do not know how copolymer chemistry, architecture, and blending ratio with the base polymer affect final membrane properties. We introduce design rules to direct the selection of best zwitterionic copolymer structures and architectures for this use. For example, copolymers with large zwitterion contents easily phase separate from the PVDF, leading to poor performance. In contrast, as little as 5 wt% of zwitterionic copolymer additive may be sufficient to prevent fouling and increase the membrane permeance by up to 6 times without a significant decline in rejection. This information enables rational design of zwitterion-containing polymers for a broader range of membrane applications.
5:30 PM - SM7.5.07
Mass Production of Electrospun Polyimide Nanofiber Membranes for Application in Li-Ion Battery and Air and Liquid Fine Filtration
Haoqing Hou 1
1 Department of Chemistry and Chemical Engineering, Jiangxi Normal University, Jiangxi China
Show AbstractElctrospun nanofibers has been attracting worldwide intensive attention due to (1) its small diameter and high specific area; (2) the highly porous nanofiber nonwovens; (3) particularly, being made in an easy way [1-6]. The highly porous nonwovens are being used or finding uses in separator for lithium battery [7], filtrations [8] among others. Future applications of nanofibers may include solar sails, light sails and mirrors in space [9]. For the above applications, electrospun nanofiber nonwovens should have good mechanical properties in order to meet the winding tension in a mechanized production process and should be able to be produced in an industrial scale for a commercial market.
To date, the electrospun nanofiber nonwovens or self-supporting electrospun nanofiber mats have, however, not been produced in a large scale. Three factors, stress of the electrospun nanofibers, reinforcement of the as-produced nonwovens via adhesion between the nanofibers, and re-dissolution of the as-produced nanofibers by the solvent vapor generated in the mass production process, may be the main reasons that retard the development of the electrospun nanofiber nonwovens. In this presentation, we introduce a way to the mass production of electrospun polyimide nanofiber nonwovens by using needled electrospinning nozzle array modules (Figure 1A). The production speed of nanofiber nonwovens directly depends on the number of used modules (Figure 1B). A production line with 30 such modules could produce 2-3 m2 nanofiber nonwovens with a surface density of 10-15 g/m2 per minute (Figure 1). The as-produced nanofiber products could be thermally treated to form the nanofiber nonwovens with an as-desired porosity or density for the battery separator application (Figure 2A), and for air purification (Figure 2B) and liquid filtration applications (Figure 2C).
As a result, the Li-ion battery with polyimide nanofiber separator shows a high safety, a high rate capability and a high cycling stability due to the heat-resistance and high porosity of the electrospun nanofiber separator; an air filter with the polyimide nanofiber nonwovens shows a 99.99% intercepting efficiency to 0.1 μm particles in air at a nanofiber loading weight of 5.0 g/m2 on PET nonwoven fabrics; a liquid filter with the self-supporting polyimide nanofiber shows a 99.9% intercepting efficiency to 4.0 μm particles in engine oil. Overall, self-supporting polymer nanofiber nonwovens could be continuously produced in a large scale by using needled electrospinning nozzle array modules, and the as-produced nanofiber products are being used or finding uses in battery fields, purification and filtration fields. For the moment, the technology level of this equipment is, however, primitive or backward. We hope to find partners to develop corresponding modern equipment and to promote a commercially production of self-supporting nanofiber nonwovens for the benefit of our humanity.
Symposium Organizers
Suzana Nunes, King Abdullah University of Science and Technology (KAUST)
Mainak Majumder, Monash University
Kuo Lun (Allan) Tung, NTU Taiwan
Ranil Wrickamasinghe, University of Arkansas
SM7.6: Membranes for Sustainable Liquid Separations
Session Chairs
Dibakar Bhattacharyya
Mary Laura Lind
Thursday AM, April 20, 2017
PCC North, 100 Level, Room 123
9:15 AM - *SM7.6.02
Integration of Nanostructured Catalytic Materials and Functionalized Membranes for Water Applications
Dibakar Bhattacharyya 1
1 , University of Kentucky, Lexington, Kentucky, United States
Show Abstract
Many current treatments for the reclamation of contaminated water sources are chemical-intensive, energy-intensive, and/or require post-treatment due to unwanted by-product formation. We demonstrate that through the integration of nanostructured metals, enzymatic catalysis, and iron-catalyzed free radical reactions within pore-functionalized synthetic membrane platforms, we are able to conduct environmentally important oxidative and reductive reactions for toxic organic degradation and detoxification from water without the addition of expensive or harmful chemicals. The availability of high-capacity membranes for efficient, selective catalysis with facile in-situ regenerability is much needed for economic and sustainable exploitation of a wide range of applications, such as green synthesis of chemicals, toxic metals removal or toxic organics destruction in polluted water. The use of commercially available high flux, MF type membranes that can be easily functionalized is an important theme of this presentation. Our low-pressure membrane approach is marked by reaction and separation selectivity and their tunability by operating pH, or pressure. The sustainable, green chemistry, approach using ambient conditions and the evaluation of reactive membranes comprising of poly acrylic acid (PAA)-modified poly vinylidene fluoride (PVDF) membrane is studied. Three distinct membrane systems will be discussed: 1) stacked-membrane with layer-by-layer assembly approach for incorporation of enzymes for tunable product yields related to water treatment, 2) stacked-membrane for hydroxyl radical-based reaction for detoxification of chloro-organics from water, and 3) in-situ, green synthesis of 20 – 50 nm Fe and Fe/Pd nanoparticles for reductive degradation of pollutants. Our approach involving nano-domain interactions, greener synthesis, and mixed matrix nano-composite membranes display remarkable versatility compared to conventional membranes. The author would like to thank NIH-NIEHS-SRC, and NSF EPSCoR program for funding various aspects of this work.
9:45 AM - SM7.6.03
Dealloying Metallic Films to Fabricate Reactive Layers in Metal-Polymer Composite Membranes
Michael Detisch 1 , T. John Balk 1 , Dibakar Bhattacharyya 1
1 Chemical & Materials Engineering, University of Kentucky, Lexington, Kentucky, United States
Show AbstractThe deposition of bimetallic films on commercial polymeric membrane support provides immense advantages, both in terms of catalytic properties and solvent resistant behavior. This study is focused on iron/palladium film fabrication on ultrafiltration type polymeric supports. Thin films of iron palladium alloy are deposited via magnetron sputtering onto a variety of porous polymer substrates. The thin films were made nanoporous through dealloying in a sulfuric acid etchant solution. The etchant selectively removes iron atoms and allows palladium to diffuse along the surface and form an interconnected ligament structure.
The resulting composite membrane shows open porosity with a characteristic pore/ligament size of 10nm. Water permeability of the resulting membrane is approximately 180 LMH/bar compared to 120 LMH/bar of the precursor membrane. This is due to a loosening of the polymer structure due to the acid wash, but also serves to illustrate the high porosity of the porous metal layer. Cross-sectioning with focused ion beam allowed the production of high quality lamellae for imaging. These cross-sections were characterized using TEM and SEM to provide high magnification images of the composite structures. XPS was also used to analyze the surface chemistry of the Fe/Pd films and the adhesion mechanisms of polymers to the metal film.
This resulting composite membrane is used as a reactive membrane in order to catalyze the degradation of chlorinated organic compounds. These compounds are toxins found in groundwater at industrial sites across the country. When supplied with hydrogen gas, palladium will remove chlorine groups from the compound, reducing its toxicity. The high surface area structure of the nanoporous films make them effective catalysts in this system. These nanoporous metallic layers have been fabricated on a variety of ultrafiltration membrane substrates. In addition to catalysis applications, these composite membranes show promise for applications in solvent resistant membrane systems and in specialized separations.
This research is supported by NIH-NIEHS-SRC and by NSF EPSCoR program.
10:00 AM - SM7.6.04
Poly(Ethylene Glycol) and Poly(Zwitterion) Grafting for Anti-Fouling Ultrafiltration Membranes
Lieu Le 1 , Suzana Nunes 1 , Mathias Ulbricht 2
1 , King Abdullah University of Science and Technology, Thuwal Saudi Arabia, 2 Technical Chemistry II, University of Duisburg-Essen, Essen Germany
Show AbstractSurface modification with hydrophilic polymers is an important strategy to prevent organic fouling in membranes for water-related applications. In this work, the efficiency of grafting poly(ethylene glycol) and poly(zwitterion) on ultrafiltration membranes has been comprehensively compared in terms of flux, protein rejection, fouling resistance and stability. Grafting poly(ethylene glycol) leads also to lower protein rejection. Compared to the unmodified membrane, both grafting techniques display antifouling improvement with lower protein absorption. Grafting poly(zwitterion) shows higher flux recovery after washing than grafting poly(ethylene glycol), which implies weak interaction between protein and zwitterion molecules and hence the fouling on poly(zwitterion) grafted surface is highly reversible. Moreover, poly(zwitterion) has high stability in common cleaning solutions such as base, acid and chlorine while poly(ethylene glycol) is chemically modified by base and chlorine solutions leading to flux and rejection changes. We optimized this approach also for hollow fiber membranes, confirming the efficiency of poly(zwitterion) grafting for membrane-based applications.
10:15 AM - SM7.6.05
Radiation Grafted, Copolymerized Fabrics for the Extraction of Uranium from Seawater
Travis Dietz 1 , Zois Tsinas 4 , Ileana Pazos 1 , Mohammad Adel-Hadadi 1 , Willliam Li 2 , Aaron Barkatt 2 , Dianne Poster 3 , Mohamad Al-Sheikhly 1
1 Materials Science and Engineering, University of Maryland, College Park, College Park, Maryland, United States, 4 Bioengineering, University of Maryland, College Park, College Park, Maryland, United States, 2 Chemistry, The Catholic University of America, Washington, District of Columbia, United States, 3 , National Institute of Standards and Technology, Gaithersburg, Maryland, United States
Show AbstractAt 3.3 ppb, the concentration of uranium in seawater is extremely small, especially in relation to many other ionic species. However the uniformity of this concentration around the world means that about 1000 times more uranium exists in the oceans than in terrestrial sources. By developing a fabric system that can extract uranium from this aqueous environment, the national supply of nuclear fuel can be extended, environmental impacts from mining can be reduced, and a technology that can assist with environmental remediation in chemical spills will be improved. Through the use of radiation grafting, uranium extracting monomers or their precursors have been copolymerized onto the backbone of high-surface area fibers composed of nylon and polyethylene, including oxalate, phosphate, and azo derivatives which have shown high affinities for uranyl ions in their ungrafted forms. The attachment of these monomers to the fabric polymer backbone was characterized with the use of Fourier transform infrared spectroscopy-attenuated total reflectance and scanning electron microscopy with energy dispersive X-ray spectroscopy. These fabrics were then exposed to seawater solutions containing both natural and spiked concentrations of seawater for different periods of time. The total uranium adsorbed by the fabrics was determined through spectrophotometric techniques as well as the use of inductively-coupled plasma-mass spectrometry. Grafted fabrics exhibited the potential to extract more than 50% of the uranium from seawater solutions spiked with 0.2 ppm uranium after one week of exposure. Further optimization of the chemical structures and the grafting morphology of the monomers must be performed in order to increase the uranium capacity of the modified fabrics.
11:00 AM - *SM7.6.06
Novel Mixed Matrix Membranes for Water Purification
Mary Laura Lind 1
1 , Arizona State University, Tempe, Arizona, United States
Show AbstractMixed matrix membranes (MMMs) offer the potential to surpass the permeability/selectivity tradeoff (e.g., the “upper bound”) of polymeric materials. We aim to develop new MMMs with improved properties (e.g., flux performance, fouling resistance, and chemical tolerance) for water purification. .
Our our patent pending molecular sieve nanocomposite membrane design consists of a liquid-barrier, chemical-resistant polymer matrix that binds a layer of selective molecular sieve nanoparticles into a flexible, robust nanocomposite thin film. This leverages (1) the high intrinsic flux and selectivity of the molecular sieve nanoparticles towards the desired product and (2) the corrosion-resistance, flexibility, and mechanical robustness of the liquid-barrier polymer support matrices. Unlike traditional polymeric membranes, our membranes do not require the polymer matrix to have liquid permeability to achieve high permeate flux which enables use of a broad spectrum of polymers with desired material properties. We formed 500nm thick water-barrier polymeric films from latex solutions on mesoporous and macroporous support membranes. We will also discuss our efforts to incorporate zeolite molecular sieves into these films for applications in reclamation of water from urine containing wastewaters for NASA.
11:30 AM - SM7.6.07
Mixed-Polyamide Thin-Film Composite Membranes with Enhanced Antifouling Properties
Phuoc Duong 1 , Kevin Daumann 2 , Mathias Ulbricht 2 , Suzana Nunes 1 , Klaus-Viktor Peinemann 1
1 , King Abdullah University of Science and Technology (KAUST), Thuwal Saudi Arabia, 2 , Universität Duisburg-Essen, Essen Germany
Show AbstractThin film composite (TFC) membranes consisting of a thin polyamide film on an asymmetric porous support have been widely used in various liquid separation applications, such as reverse osmosis, forward osmosis, nanofiltration, and organic solvent nanofiltration. The polyamide film is thin, highly permeable, and dense. Hence the TFC membrane has high flux and good selectivity. However, the polyamide TFC membrane is prone to fouling because of the rather hydrophobic character and the rough surface of the polyamide film. In this study, we demonstrate strategies for fabricating innovative mixed-polyamide films containing antifouling segments, i.e., dendrimers and zwitterionic co-polymer. Different generations of amino-functional dendrimers and the laboratory self-designed di-block amino-functional zwitterionic co-polymer are investigated. Dendrimers and zwitterionic co-polymer are chemically embedded into the polyamide film by interfacial polymerization reaction between blended dendrimer/or zwitterionic co-polymer and m-phenylene diamine at various ratios in aqueous phase and trimesoyl chloride in organic phase. The impacts of the concentration of antifouling segments on the formation and performance of the free-standing mixed-polyamide films and the mixed-polyamide TFC membranes are investigated. Higher concentration of antifouling segments leads to a more hydrophilic and smoother mixed-polyamide film. Depending on the composition of the mixed-polyamide film, a hydrophilic and smooth layer with <10 nm roughness could be obtained. Mixed-polyamide TFC membranes shows much better protein and organic fouling resistance compared to the conventional polyamide TFC membrane. This work demonstrates the feasibility of fabricating TFC membranes with the reduction of fouling deposition by using a single polymerization process.
11:45 AM - *SM7.6.01
Novel Activation Techniques of PVDF Flat Sheet Membranes
Samer Al-Gharabli 1 , Joanna Kujawa 1 , Musthafa Mavukkandy 1 , Hassan Arafat 1
1 , Masdar Institute of Science and Technology, Abu Dhabi United Arab Emirates
Show AbstractPolyvinylidene fluoride (PVDF) membranes play a key role in several industrial applications due to their favorable properties, including their high chemical stability. In water filtration applications (micro- and ultra-filtration) for example, the majority of polymeric membranes on the market today are made of PVDF. Tuning the properties of this material enables a sharp selectivity for the target application. One of the direct methods to achieve this goal is the selective functionalization of PVDF membranes with labile groups like OH. In this work two effective methods of PVDF functionalization were developed as efficient fabrication protocols of functionalized PVDF flat sheet membranes. In the first method, two-step alkali/acid treatment was optimized and developed. The advantage of the said method was the application of short modification time under mild stress of alkali media (5% KOH). Extensive physicochemical (e.g., contact angle, surface free energy, surface tension, and work of adhesion), material (e.g., pore size distribution) and surface (e.g., roughness) characterization of the prepared membranes were done. Moreover, deep wetting characterization analysis of the modified membranes was done by determining the mechanism of wetting (dynamic measurements), critical surface tension, and spreading pressure. Strong influence of roughness on the hydrophobicity of the membrane was observed and hence the modified membranes possessed contact angle values higher than 120o. The efficiency of the alkali treatment was determined by TGA-MS, ATR-FTIR, and Raman spectroscopy.
In the second method, a novel reagent was utilized at mild condition of temperature (room temperature), concentration (20%) and time of treatment (from 30 seconds to 30 minutes) to functionalize the PVDF membrane surface. An experimental protocol for the hydroxyl group functionalization using this reagent was developed, optimized and implemented with successful outcome. The reaction conditions were optimized to develop flat sheet membrane morphology and performance. The properties of the membrane were thoroughly evaluated and characterized using a wide range of tools.
12:15 PM - SM7.6.09
Fabrication of Greener Membranes from Ionic Liquid Solutions
DooLi Kim 1 , Suzana Nunes 1
1 , KAUST, Thuwal Saudi Arabia
Show AbstractMembrane technology plays a crucial role in different separation processes such as biomedical applications, food industry, drinking water supply, and wastewater treatment. However there is a growing concern with the environmental and health impact of solvents used in the membrane fabrication. Hence, interest in substituting harmful solvents to safer chemicals has increased. To explore the possibility of replacing toxic solvents like dimethylformamide (DMF) by less toxic solvents like ionic liquids, polymers commonly used for membrane fabrication, such as polyacrylonitrile (PAN); polyethersulfone (PES); and cellulose acetate (CA), were dissolved in ionic liquid solutions. Flat sheet and hollow fiber membranes were fabricated with solutions in the newly explored ionic liquids and compared to analogous membranes prepared from solutions in conventional organic solvents, such as DMF and dimethylsulfoxide (DMSO). Thermodynamics of the polymer solutions, kinetics of the phase inversion, and kinetic factors, which resulted in significant differences in the membrane structure compared to those of membranes fabricated from toxic solvents, were examined. After the theoretical prediction experimentally proved, fabricated membranes were characterized. Higher water flux with smaller pores, unique and uniform morphologies, and higher pore distribution, were measured in the membranes fabricated with the ionic liquid. Furthermore, outstanding performance on separation of peptides and proteins with various molecular weights was observed in the membranes fabricated from ionic liquid solutions. In summary, we propose less hazardous polymer solutions to the environment, which can be used for the membrane fabrication with better performance and more regular morphology.
12:30 PM - *SM7.6.10
Organic Solvent Nanofiltration with Novel Perfluoropolymer Membranes
Kamalesh Sirkar 1 , John Chau 1 , Prithis Basak 1
1 , New Jersey Inst of Technology, Newark, New Jersey, United States
Show AbstractA very large variety of membranes polymeric or otherwise have been investigated over the last two decades for organic solvent nanofiltration (OSN). The materials and structures used to make OSN membranes include among others the following: poly (dimethylsiloxane) (PDMS); mixed matrix membranes (MMMs) of PDMS with zeolites and other fillers; asymmetric integrally skinned polyimide (PI) membrane crosslinked with aromatic or aliphatic diamines; polyaniline; polypyrrole; interfacially polymerized polyamide with or without functionalized carbon nanotubes; carbon-based membranes including graphene. Most of the studies involved polymeric membranes. One of the weaknesses of most polymeric membranes is their varying tendencies for swelling with demanding organic solvents aprotic or otherwise; this gets reflected in the solute rejection behaviors of such polymers. Diamine-crosslinked PI membranes show excellent resistance to organic solvents but have some swelling in the presence of water. To this end we have started studying membranes from particular classes of fluoropolymers which are extremely inert. Initially these membranes were studied for pervaporation-based selective removal from organic-organic mixtures and aqueous-organic mixtures. Next they were studied with a variety of solvents and solvent mixtures for OSN over a considerable pressure range. We report results of solvent flux and solute rejection for such membranes using dye solutes. These studies were made with dense flat membranes of different thicknesses supported on appropriate porous supports.
SM7.7: Membranes for Gas Separations
Session Chairs
Thursday PM, April 20, 2017
PCC North, 100 Level, Room 123
2:30 PM - *SM7.7.01
Ionic Liquid Composite Membranes for CO2/Light Gas Separations
Richard Noble 1 , Douglas Gin 1 2 , William McDanel 1 , Matthew Cowan 1 , Zoban Singh 1
1 Chemical & Biological Engineering, University of Colorado, Boulder, Colorado, United States, 2 Chemistry & Biochemistry, University of Colorado, Boulder, Colorado, United States
Show AbstractA novel approach for performing these separations is to use room temperature ionic liquids (RTILs) in various morphologies as membranes. In comparison to conventional polymers, they perform gas separations due to solubility differences. They can be converted to polymerizable molecules. This allows promising RTILs to be prepared as membranes. Thus, they can be converted to various morphologies as membranes while maintaining the inherent selectivity of the material. They can be prepared as polymer films, composite structures with ionic liquid within the structure and gels. Polymer films have been tested for gas separations up to 40 bar feed pressure. The conditioning or morphology change due to the incorporation of gases such as CO2 at these high pressures is reversible. This is an important advantage in comparison to conventional polymers. The wide range of morphologies and chemical structures allow for finding materials that not only have the desired physicochemical properties but also the mechanical properties needed to produce viable membranes.
Mixed matrix membranes (MMMs) look to be a very promising candidate for commercialization and large scale implementation. These MMMs consist of three individual components: polymerizable room temperature ionic liquids (poly(RTILs), normal RTILs, and zeolite particles. These components synergize to produce enhanced gas transport. The polymer matrix allows for facile and economical fabrication, while the zeolite provides excellent separation performance. The RTIL prevents defect formation within the membrane by acting as a wetting agent to help the polymer matrix interface aptly with the zeolite. We have investigated how varying the three components in our MMMs affects membrane permeability and selectivity. This initial study identified the optimal type of zeolite particles. More in depth analysis of the ionic liquid revealed the significance of molar volume in the RTIL and free volume in the poly(RTIL) on the membrane’s gas separation ability. Previous work established the correlation between increasing RTIL molar volume and decreasing CO2 solubility selectivity. Current work shows how the polymerized analogues (poly(RTILs) display a similar trend with free volume. This resulted in the creation of MMMs made with smaller molar and free volume RTILs and poly(RTILs) that performed above Robeson’s 2008 upper bound for CO2/CH4. With this knowledge we aim to devise a systematic design approach for creating state of the art MMMs.
3:00 PM - *SM7.7.02
Towards MOF Membrane Technology—High-Performance Separations via Mixed-Linker ZIFs and Membrane Processing on Polymeric Hollow Fibers
Sankar Nair 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractThis talk will describe our progress in the synthesis and properties of ZIF-type MOF materials and their subsequent use in scalable fabrication processes to obtain molecular sieving membranes on polymeric hollow fibers. Membrane separation is a key component of strategies targeting step changes (rather than incremental ones) in cost and energy-efficiency during production of fuels and chemicals from conventional and renewable feedstocks. Two important barriers to the development of MOF membrane separation technology are (i) the difficulty in obtaining tunable, high-performance, and robust molecular sieving materials; and (ii) the lack of low-cost, scalable membrane fabrication processes. A multiscale approach to membrane fabrication process engineering is required to overcome these barriers. We will demonstrate that the mixed-linker approach to synthesis of ZIF-type MOFs offers a path towards fine (sub-Ångstrom) control of pore structure and separation properties. Furthermore, we will discuss how such materials can be processed into polycrystalline membranes on a scalable hollow fiber platform, with control over nanometer-scale defects as well as micron-scale transport and film crystallization phenomena within the hollow fibers. These membranes allow high-performance separations of molecules such as hydrogen, light olefins, and isomers. The talk will conclude with examples of generalizing the above strategy towards a versatile MOF membrane technology that addresses a wider range of molecular separation targets.
3:30 PM - SM7.7.03
CO2-Philic Polymer Membranes for High Flux CO2 Separation
Tao Hong 2 , Pengfei Cao 1 , Bingrui Li 1 , Shannon Mahurin 1 , De-en Jiang 3 , Konstantinos Vogiatzis 2 , Jimmy Mays 2 , Brian Long 2 , Alexei Sokolov 1 2 , Tomonori Saito 1
2 Department of Chemistry, University of Tennessee, Knoxville, Tennessee, United States, 1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 3 Department of Chemistry, University of California, Riverside, Riverside, California, United States
Show AbstractThe vast majority of the world’s energy is presently derived from the burning of fossil fuels, which releases vast quantities of carbon dioxide (CO2) into the environment and results in undesirable climate change. Practical and cost efficient methods of CO2 separation and capture would thus solve one of the most challenging problems today. This presentation summarizes our effort on the development of novel polymer membranes functionalized with CO2-philic groups for high flux CO2 separation. Our strategy focuses on tuning solubility selectivity in addition to diffusivity selectivity for achieving high permeability membranes combined with good selectivity. Various synthetic techniques including ROMP and post functionalization were used and the careful design permits to prepare well-defined novel high permeable polymers containing CO2-philic groups. This study demonstrated the addition of CO2-philic groups (e.g. amidoxime and PEO) significantly increased the solubility selectivity of CO2 over N2. The membrane performance is also highly dependent on the balance of gas/functional group interaction, intra/inter- molecular interaction (H-bonding etc.) of membrane, packing, and polymer dynamics. Tuning the balance of the interaction enables to achieve the CO2 separation performance over the Robeson upper bound, e.g. CO2 permeability 3000-8000 Barrer and CO2/N2 selectivity 18-20. The structure-property relationships especially on CO2 uptake, CO2 and N2 permeability, CO2/N2 selectivity to the polymer structure will be discussed.
3:45 PM - SM7.7.04
Heterocyclic Building Blocks Transformation to Nanoporous Carbons—Toward a Very High Surface Area and CO2 Uptake
Babak Ashourirad 1 , Katie Cychosz 2 , Matthias Thommes 2 , Hani El-Kaderi 1
1 , Virginia Commonwealth University, Richmond, Virginia, United States, 2 , Quantachrome Instrument, Boynton Beach, Florida, United States
Show AbstractCarbon dioxide (CO2) release into the atmosphere from coal burning industries has been regarded as the major culprit causing global warming. Therefore, CO2 capture and sequestration (CCS) technology has been the subject of many research areas and studies as a short-term remedy, until renewable energy sources replaced by fossil fuels. In this study, benzimidazole building unit as an inexpensive, commercially available and single-source precursor with high level of nitrogen (~24 wt%) was successfully transformed to highly porous carbons. One-step chemical activation/carbonization with potassium hydroxide was applied to develop porous structure and further add oxygen heteroatom to the system simultaneously. The optimum level of microporosity and heteroatoms can be achieved by tuning the amount of activator and carbonization temperature. The highest CO2 uptake values at 0.1 bar (1.60 mmol g-1), 1 bar (5.46 mmol g-1), and 30 bar (28.10 mmol g-1) were recorded for three different carbons at 298 K. The synergistic effect of narrow micropores and electronegative heteroatom functionalities also gives an edge to prepared porous carbons for selective adsorption of CO2 over other gases such as CH4 and N2. The proposed method and materials indicate that heteroatom-doped porous carbons are among the best materials for CO2 capture from post-combustion gas mixture as well as natural gas upgrading. The fabrication of monomer-derived carbons is straightforward, reproducible and could be easily scaled up.
4:30 PM - SM7.7.05
Computational Characterization of Highly Selective Separation Processes Using a Novel Covalent Organic Framework Woven Material
Yaset Acevedo 1 , Paulette Clancy 1
1 , Cornell University, Ithaca, New York, United States
Show AbstractAdvances in organic thin films and membranes have been developed for decades for catalysis, gas storage, and separations. While nanofiltration and reverse osmosis are widely applied in separations at the nanoscale, there is an ongoing need to improve size and chemical selectivity in organic membranes. To address this need, we need a better understanding of the relationship between nanoscale structure and macroscale properties. This is especially true for new materials. At the near-molecular-scale of some of the newest materials, understanding structure-property relationships are challenging for experimental techniques, but tailor-made for computational modeling and simulation. We model and assess the viability for a very new material, COF-505, a 3D covalent organic framework “weave” to selectively control gas adsorption and characterize its molecular scale morphology.
COF-505 is a unique member of the COF family. Unlike typical COFs, which have fairly rigid frameworks, COF-505 features an elastic material that consists of a weave of intertwined chains composed of bisphenanthroline and benzidine. Copper centers are present during fabrication of this material; these metal centers can be reversibly removed and re-added without loss of COF structure. Demetalation is associated with a ten-fold increase in elasticity. Because of this unique property, we expect the interface between the organic weave and adsorbing gas molecules to be highly dependent on temperature and pressure, giving us two accessible and sensitive “levers” to tune to suit the requirements of a variety of applications. The woven composition of COF-505 endows the material with permanent porosity and is durable against fluctuations in temperature and pressure. Using Molecular Dynamics and Density Functional Theory, validated against experimental data, we explore the diffusion and adsorption properties of various gases in this unique material. In particular, we probe the capability of COF-505 to act as a responsive molecular sponge through the selective adsorption of gas molecules.
4:45 PM - SM7.7.06
Ambient-Temperature Synthesis of Two-Dimensional Metal-Organic Frameworks for Gas Separation
Jie Zha 1 , Xueyi Zhang 1
1 Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractTwo-dimensional (2D) metal-organic frameworks (MOFs), as a new member of 2D materials family, have received extensive attention due to the proper integration of tunable structure and chemical functionality of MOF materials with the high aspect ratio nature of the 2D morphology, which is beneficial for a wide range of practical applications, such as gas separation, surface sensing, and catalysis. The main challenge in the fabrication of 2D MOFs lies in controlling the growth direction of MOF crystals, because the high symmetry of MOF building units usually favors the formation of highly symmetrical or isotropic morphologies. In this present work, we demonstrated that 2D MOFs (or MOF nanosheets) with controllable size and morphology can be readily achieved by adjusting the coordination interaction between metal center and ligands, where all syntheses can be done at ambient temperature using conventional one-step nucleation-growth method. The coordination interaction was directly investigated by ultraviolet-visible spectroscopy (UV-Vis) and further quantified by the Lewis basicity of ligands. The morphology and size of MOF nanosheets were confirmed with the assistance of microscopy techniques, e.g., transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The resultant MOF nanosheets were fabricated into membranes via spin coating method and the MOF nanosheet membranes revealed promising performance in N2/CO2 and CH4/CO2 separations. The synthetic protocol of 2D MOFs investigated in this work aims to paves the way to understanding morphology control of MOF nanoparticles, and to prepare MOF nanoparticles for a broader spectrum of applications.
5:00 PM - SM7.7.07
Dynamic Gas Transport through Polymeric Membranes
Marielle Soniat 1 2 , Meron Tesfaye 1 2 , Daniel Brooks 3 , William Goddard 3 , Boris Merinov 3 , Adam Weber 1 , Frances Houle 1
1 Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 , University of California, Berkeley, Berkeley, California, United States, 3 , California Institute of Technology, Pasadena, California, United States
Show AbstractRenewable energy-conversion devices operate under continually varying conditions; as such, the functioning of their components, especially polymeric gas-separation membranes, may be affected. Steady-state permeation theory, which provides information on permeant solubility and diffusion, does not describe dynamic changes in operating conditions. We will present data from a new experimental-modeling study specifically designed to develop an understanding of the kinetics of gas-membrane systems' response to abrupt changes in permeant concentration. The experimental studies obtain pressure-rise histories for gases that have traversed a polymer membrane from initial vacuum to steady state using a custom-built, fixed volume, gas-permeation system. This study focuses on a rubber, poly(dimethyl siloxane) (PDMS), as the simplest case for validation of the foundational kinetic model for gas transport through polymeric membranes. The time-varying interaction of these polymers with gases is captured using low to high condensing gases like N2 and CH4 and an inert to plasticizing gas like Ar and CO2. Coupled reaction-diffusion kinetics simulations of measured time histories and molecular dynamics calculations are used to identify key characteristics of uptake and mobility changes occurring in these systems. The core mechanistic scheme has been validated using related literature experiments on quenching of dye-in-polymer phosphorescence during O2 permeation. Trends found for dynamic permeation behavior with gas type will be discussed. Since the reaction-diffusion kinetics are physically based and therefore predictive, they can be used to calculate permeation under intermittent conditions for the systems investigated. Typical performance characteristics extracted from the simulations including transient permeant profiles in the polymer will be described.
5:15 PM - SM7.7.08
Metamaterial Membranes for Chemical Separations
Juan Restrepo-Florez 1 , Martin Maldovan 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractMembrane-based separation technologies are generally based on the use of isotropic materials and separation of chemical compounds occurs as a consequence of the different solubilities and diffusivities of the compounds in the membrane. In recent years, the design of membrane-based separations has been focused on the development of chemical approaches to modify the solubility and/or diffusivity of the chemical compounds. In this work we describe a radically new approach for the design of membrane separation systems. We achieve separation of an arbitrary mixture of two compounds A and B by means of an anisotropic engineered metamaterial structure that redirects each compound towards different spatial locations. Specifically, we employ metamaterials to rationally design the anisotropic diffusivity of two arbitrary chemical compounds in a composite structure (metamaterial membrane) such that separation is achieved by guiding the compounds to different places. The composite metamaterial structure can be experimentally achieved by using three different isotropic and homogenous materials. We present a practical design in which oxygen and nitrogen are separated in a polymeric metamaterial membrane and illustrate the performance of the device in terms of structural features and constituent materials. Our results suggest that rationally designed metamaterial structures can enhance the separation capabilities of isotropic constituent materials.
5:30 PM - SM7.7.09
Edge Charge Neutralization of Clay for Improved Oxygen Gas Barrier in Nanobrick Wall Thin Films
Yixuan Song 1 , David Hagen 1 , Shuang Qin 1 , Kevin Holder 1 , Kyle Falke 1 , Jaime Grunlan 1
1 , Texas A&M University, College Station, Texas, United States
Show AbstractLayer-by-layer (LbL) assembled polymer-clay multilayer thin films are known to provide transparent and flexible gas barrier. In an effort to further lower the oxygen transmission rate (OTR) of these nanobrick wall thin films, sodium chloride was introduced into montmorillonite (MMT) suspension as an “indifferent electrolyte”. At pH 6.5 the amphoteric edge sites of MMT have a neutral net charge, and a moderate concentration of NaCl effectively shields the charge from neighboring platelets, allowing van der Waals forces to attract the edges to one another. This edge-to-edge bonding creates a much more tortuous path for diffusing oxygen molecules. An 8 bilayer (BL) polyethyleneimine (PEI)/MMT multilayer coating, assembled with 5 mM NaCl in the aqueous clay suspension, exhibited an order of magnitude reduction in oxygen permeability (~4×10-20 cm3*cm/(cm2*Pa*s)) relative to its salt-free counterpart. This result represents the best barrier among polymer-clay bilayer systems, which is also lower than the SiOx or AlxOy gas barrier coatings reported. At higher NaCl concentration, the strong charge screening causes edge-to-face bonding among MMT nanoplatelets, which leads to misalignment in assembled films and increased OTR. This “salty-clay” strategy provides an efficient way to produce better multilayer oxygen barrier thin films by altering ionic strength of the MMT suspension. This simple modification reduces the number of layers necessary for high gas barrier, potentially making these multilayer films interesting for commercial packaging applications.
5:45 PM - SM7.7.10
Long-Term Flexibility-Based Structural and Chemical Evolution in Microporous Organosilica Membranes—A Problem and Solution
Petra Dral 1 , Kristianne Tempelman 1 , Emiel Kappert 1 , Louis Winnubst 1 , Nieck Benes 1 , Johan Ten Elshof 1
1 , MESA+ Institute for Nanotechnology, Enschede Netherlands
Show AbstractMicroporous organosilica membranes are made from bridged silsesquioxane precursors and have demonstrated a remarkable hydrothermal stability in molecular separation processes (gas separation, pervaporation, reverse osmosis) since their discovery in 2008, making them the first generation of ceramic molecular sieving membranes with sufficient performance under industrially relevant conditions (ChemCommun 2008, 1103; Adv. Funct. Mater. 2011, 21, 2319). These organosilica membranes are thermally consolidated at 250-300 °C for a few hours, after which the material structure is assumed to be stabilized. However, it has been noted that the membranes display a slow ongoing flux decline for more than a year during steady operation at 95-150 °C (e.g. J. Mater. Chem. 2008, 18, 2150; J. Membr. Sci. 2011, 380, 124). To date, this problem of a time-dependent flux is not understood and has not been solved.
We present an in-depth study on ongoing chemical and structural changes in organosilica membranes at elevated temperatures. To monitor the subtle changes in these materials in time, a range of in-situ analysis techniques has been employed, including fourier-transform infrared spectroscopy, spectroscopic ellipsometry and gas permeation. The common assumption that the material reaches a stabilized structural state after treatment at 250-300 °C for a few hours is shown to be incorrect. Ongoing chemical condensation, network shrinkage and decreasing density occur and have competing effects on the pore structure; gas permeances progressively increase or decrease depending on the pore size. To overcome this instability, we present a novel post-synthesis stabilization approach based on iterative hydrolysis and condensation. Stimulating bond breakage and reformation in a controlled fashion allows the organosilica network to reorganize into a more stable configuration.
Symposium Organizers
Suzana Nunes, King Abdullah University of Science and Technology (KAUST)
Mainak Majumder, Monash University
Kuo Lun (Allan) Tung, NTU Taiwan
Ranil Wrickamasinghe, University of Arkansas
SM7.8: Membranes from 1D and 2D Materials
Session Chairs
Wanqin Jin
Mainak Majumder
Friday AM, April 21, 2017
PCC North, 100 Level, Room 123
9:30 AM - *SM7.8.01
Membrane Distillation and Evaporation with Carbon Based Materials—Prospects and Advances
Ludovic Dumee 1 , Zhifeng Yi 1 , Lingxue Kong 1 , Mainak Majumder 2
1 Institute for Frontier Materials, Deakin University, Waurn Ponds, Victoria, Australia, 2 Department of Mechanical Engineering, Monash University, Clayton, Victoria, Australia
Show AbstractThe development of novel materials for desalination application of water and mixed solvents by membrane distillation and evaporation will be first discussed in light of physical and morphological process requirements. Carbon based materials offer unique structure-properties relationships beneficial to membrane separation applications. Membrane distillation/evaporation are two emerging areas in separation requiring advanced surface texture and pore morphologies design, with potential for low cost and super-efficient desalination. Here, the recent developments of graphite based, including carbon nanotube and graphene primarily, materials for these applications will be reviewed and presented. Novel graphene coatings applied across porous materials to promote evaporation and vapour diffusion will also be presented. The prospects for these materials to sustain extremely harsh conditions of pH and solvents will also be demonstrated.
10:00 AM - *SM7.8.02
1D and 2D Boron Nitride Membranes for Water Separation
Davide Mattia 1
1 , University of Bath, Chemical Engineering Department, Bath United Kingdom
Show AbstractBoron nitride (BN) is structurally similar to graphene and can be easily fabricated into 1D and 2D (nanotubes and nanosheets) single or multi-layer structures, as with its carbon analogue. In addition, it presents some unique characteristics that make it attractive for separation processes. In particular, the B-N bond is partially ionic due to the difference in electronegativity of B and N as compared to the covalent C-C bonds of graphene. This would mean that BN could be used in separating compounds with different polarity in water purification and organic solvent filtrations. Furthermore, BN has excellent corrosion resistance, high thermal conductivity and chemical and oxidation resistance, which could make it interesting for other separations processes, such as pervaporation.
In this presentation, the preparation of boron nitride nanotube (BNNT) and boron nitride nanosheet (BNNS) membranes is reported for the first time. The BNNT membranes were prepared via chemical vapour deposition using anodic alumina – carbon nanotube membranes as templates, and boron and nitrogen gaseous precursors. The result is a BNNT membranes with aligned pores (tortuosity ~1), controlled pore diameter and narrow pore size distribution. The BNNSs, on the other hand, were prepared using a sonicated-assisted hydrolysis method, with water acting as dissolving and cleaving agent of hexagonal boron nitride (h-BN) powder and at room temperature. Under high sonication power, the hydrophobic h-BN powder in water was exfoliated into nanosheets, forming a colloidal solution, stabilized by the formation of hydroxyl groups at the cleaved terminal edges. The as-synthesized BNNSs, with an average size of ~ 300 nm, were then deposited onto porous organic commercial substrates by vacuum filtration of the BNNSs solution.
The pure water permeability of the BNNT and BNNS membranes was tested and compared to carbon nanotube and graphene membranes, respectively, showing comparable performance. Filtration using liquids of different polarities or salt concentration showed the superior performance of the BN-based membranes in terms of permeability-rejection performance compared to the C-based ones. Finally, in the case of the BNNTs, pure water permeability and flow enhancement are analysed using a theoretical model which highlights the effect of the different material chemistry on water flow compared to the case of carbon nanotubes.
10:30 AM - *SM7.8.03
Voltage Activated Membrane Platforms for Drug Delivery and Bioseparation
Bruce Hinds 1
1 , University of Washington, Seattle, Washington, United States
Show AbstractAn important challenge for the membrane community is to mimic the dynamic activity of natural protein channels that outperform by orders of magnitude man-made systems based on pore size and coarse chemical selectivity. To mimic protein channel pumping on a robust engineering membrane platforms applied bias can be used to actuate charged gatekeepers and induce ionic pumping. Described here are two platforms of Carbon nanotube membranes and Anodized Aluminum Oxide (AAO) with nm-thick electrodes at pore entrances/exits. Carbon nanotubes have three key attributes that make them of great interest for novel membrane applications 1) atomically flat graphite surface allows for ideal fluid slip boundary conditions and extremely fast flow rates [1,2] 2) the cutting process to open CNTs inherently places functional chemistry at CNT core entrance for chemical selectivity and 3) CNT are electrically conductive allowing for electrochemical reactions and application of electric fields gradients at CNT tips. The CNT membrane, with tips functionalized with charged molecules, is a nearly ideal platform to induce electro-osmotic flow with high charge density at pore entrance and a nearly frictionless surface for the propagation of plug flow. Through diazonium electrochemical modification we have successfully bound anionic surface charge to CNT tips and along CNT cores. High electro-osmotic flows of 3 cm/s-V at are seen that are 10,000 fold faster than in conventional nanoporous materials[3,4] and are consistent with pressure driven flow enhancements. Use of the electro-osmotic phenomenon for responsive/programmed transdermal drug delivery devices for nicotine addiction [5]. Another approach is to mimic natural protein channel transport cycles with binding/transport/release/reset events. Porous alumina (AAO) membranes have top and bottom electrodes coated with thin Au layers with pore dimension tuned to match protein dimensions. At this thin layer at pore entrances, Ni-ETA is able to bind to hys-tag residue on target protein, as is commonly employed in chromatography. A binding voltage pulse attracts anionic target protein to top electrode and blocking the pore, while repelling the cationic imidazole release agent. The second voltage cycle attracts cationic release agent to top of membrane while pumping anionic target protein to bottom permeate and resetting the pumping cycle. This system was able to successfully mimic natural membrane transporter cycles and the separation efficiency of 1cm2 of membrane was comparable to convention 1cm3 volumes used in chromatography [6]
[1] Nature 2005, 438, 44. [2] ACS Nano 2011 5(5) 3867-3877 [3] RCS Nanoscale 2011 3(8) 3321-28 [4] Proc. Nat. Acad. Sci. 2010 107(26) 11698-11702. [5] Nature Nano 2012 7(2) 133-39 [6] Advanced Functional Materials 2014 24(27) 4317-23
11:30 AM - SM7.8.04
Overview of Research on Graphene-Based Membranes: Opportunities and Challenges
Mainak Majumder 1
1 Nanoscale Science and Engineering Laboratory (NSEL) and Department of Mechanical & Aerospace Engineering, Monash University, Clayton, Victoria, Australia
Show AbstractGraphene, the atomically thin monolayer of carbon atoms, has received wide attention in recent years. From the perspective of membranes, graphene, is an exciting material. Given that permeation speed scales inversely with the thickness of a membranes, a monolayer of atoms, at least conceptually promises the lowest possible transport resistance. However, graphene, in itself is impermeable, so several studies have shown methods to ‘drill’ well-controlled nanometric or smaller holes with large density (~10 12 cm2) in single layer graphene. These membranes have shown molecular sieving properties and also expectedly, fast mass transport properties; selectivity is however controlled by the size of the nanometric pores and hydrodynamic entrance effects.
Graphene membranes can also be formed by stacking of sheets of graphene-oxide. The procedure is relatively simple and there are possibilities of scaling up rather easily. However, compared to the single-layer graphene membranes, the permeability is a strong function of the number of layer that are stacked as well as the structural order of the assemblies. Transport through this labyrinthine structure is quite complex and many factors determine the permeability/selectivity properties such as the interlayer gallery distance, presence of defects and proportion of sp2 (graphitic) and sp3 bonds (carbon-oxygen), and even the presence of adsorbed water inside the graphene-oxide channels. Several promising applications for these types of membrane have been demonstrated such as molecular sieving typically in the 400-1000 Da molecular weight range, selective permeation of water vapour over organic components such as ethanol leading to pervaporation-type separations. The advantages of membranes produced by this approach has the best of both the worlds - they can be processed like polymers, yet has the chemical inertness of carbon which means that these membranes have potential for applications in harsh chemical environments such as extreme pH or temperature as well as survival in aggressive chemical cleaning protocols. These developments have led to an explosive growth in the field of graphene-based membranes.
Many challenges still remain: understanding the transport properties are essential to develop reliable applications, controlling the inter-layer gallery distance both increasing and decreasing the size to tune the molecular weight cut-off, and improving methods to produce these membranes in commercially attractive scales are just a few of them. With methods to produce graphene or graphene oxide reasonably established and being produced in industrial scales and realizable application demonstrated, the future of the field is bright.
11:45 AM - SM7.8.05
Water Transport and Ion Selectivity in Sub-1-nm Diameter Carbon Nanotube Porins
Ramya Tunuguntla 1 , Robert Henley 2 1 , Yun-Ciao Yao 1 3 , Meni Wanunu 2 , Aleksandr Noy 1 3
1 , Lawrence Livermore National Lab, Livermore, California, United States, 2 , Northeastern University, Boston, Massachusetts, United States, 3 , University of California Merced, Merced, California, United States
Show AbstractLiving systems control transport of ions or small molecules across biological membranes using ion channels that form pores in lipid bilayers. Membrane pores formed by ultra-short carbon nanotubes (CNTs) assembled in the lipid membranes have transport properties that come remarkably close to replicating the transport properties of biological channels. The defining features of these nanostructures are their inner pores that have atomically smooth hydrophobic walls, which can confine water on a molecular level, and, in case of 0.8 nm diameter CNTPs, down to a single-file configuration. We present experimental results that demonstrate efficient water transport in CNTPs and explore its physical origins. We also use single pore conductance measurements to demonstrate ion selectivity in these pores and show that they can be configured into switchable nanofluidic diodes. CNT porins represent a simplified biomimetic system that is ideal for studying fundamentals of nanofluidic transport and transport in biological channels, and for building complex engineered mesoscale structures that could be the foundation of next-generation membrane technologies. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award SCW0972. Work at the Lawrence Livermore National Laboratory was performed under the auspices of the U.S. Department of Energy under Contract DE-AC52-07NA27344.
12:00 PM - SM7.8.06
Ultra-Breathable Carbon Nanotube Membranes
Francesco Fornasiero 1 , Ngoc Bui 1 , Eric Meshot 1 , Sangil Kim 1 , Jose Pena 1 , Chaitai Chen 1 , Phillip Gibson 2 , KuangJen Wu 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States, 2 , U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, Massachusetts, United States
Show AbstractPrevious reports for pressure-driven transport through CNT membranes demonstrated CNT permeability values that were orders of magnitude larger than those predicted by Knudsen diffusion theory for gases (~102 fold enhancement) and by Hagen-Poiseuille equation for liquids (103-105 fold). While these results spurred great interest in CNTs for efficient membrane separations, it remains an open question if driving forces other than pressure could result in similar transport rate enhancements. A positive answer would greatly extend the promises and application space of CNTs as fluidic channels.
In this work, we provide the first experimental evidence of enhanced gas transport in CNTs driven by a concentration rather than a pressure gradient. We fabricated cm2, free-standing, flexible, 1-5 nm SWNT/parylene membranes with well-aligned nanotubes as only transporting pores, and we measured the water vapor diffusion rate through the membrane when each surface is exposed to a different relative humidity. Our measurements demonstrate that these membranes exhibit rates of water vapor transport (~8000 gr/m2day) that surpass those of commercial breathable fabrics, even though the CNT pores are only a few nm wide and the overall porosity is less than 5.5%. Measured permeability of our CNT channels is 24 times larger than Knudsen diffusion prediction, and this flow enhancement is close to that measured for pressure-driven transport of nitrogen.[1] Membranes made from 1-3 nm SWNT forests with higher number densities (> 1012/cm2) display even larger gas-transport enhancements.
This ultrafast rate of water vapor transport in CNTs suggests that CNT membranes hold great potential for pervaporation, membrane distillation, and as building block of breathable and protective fabrics. For the last application, a membrane shall be able to block dangerous components while permitting perspiration. By demonstrating complete rejection of 3-nm charged dyes, 5-nm uncharged gold (Au) nanoparticles, and ~40-60-nm Dengue virus from aqueous solutions during filtration tests, we provide evidence that, in addition to outstanding breathability, our CNT membranes provide a high degree of protection from bio-threats by size exclusion.[1]
This work was supported by the Defense Threat Reduction Agency (DTRA) D[MS]2 project under Contract No. BA12PHM123 and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
[1] N. Bui, E. R. Meshot, S. Kim, J. Peña, P. W. Gibson, K. J. Wu, F. Fornasiero, Adv. Mater. 2016, 28, 6020.
12:15 PM - SM7.8.07
Controlling Water and Ion Transport in Modified Graphene Oxide Membranes for Water Purification
Kevin Zavadil 1 , Laura Biedermann 1 , Michael Hibbs 1 , Michael Hightower 1 , Curtis Mowry 1 , Adam Pimentel 1 , Victor Pinon 1 , Craig Stewart 1
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractEnergy efficient, cost-effective separation of inorganic and organic impurities from water is required to enable energy generation and production through water recycling and treatment. Modified graphene oxide (mGO) membranes appear as viable separation materials due to high water permeance at low pressure. Fluid and ion transport within well-assembled mGO membranes is defined by the size (d spacing) and chemical properties of the intersheet channels. These attributes can be tailored through synthetic modification of the graphene oxide. In this paper, we describe optimized ultrafiltration membranes of laminar mGO on polymer supports that are mechanically robust, capable of supporting water permeance of 2 - 4 LMH/bar (at 7 – 14 bar) with sulfate anion rejection at 90%, and tolerance to <10 ppm chlorine exposure to prevent biofouling. Membrane stability is provided by covalently attaching the membrane to the porous polymer substrate. Current work is focused on correlating permeance and ion rejection with membrane d spacing controlled by both chemical cross-linking and by hydrostatic pressure. Several novel methods of cross-linking are employed to tune d spacing ranging from the equilibrium >1 nm water bilayer to values approaching that of dry GO. In situ x-ray diffraction is used to characterize d spacing while cross-flow permeance coupled with ion chromatography characterize transport and rejection properties. Our results define a path forward for tailoring mGO membranes for energy efficient and cost-effective water recycling/treatment.
This work is supported by Sandia National Laboratoratories. Sandia is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE’s NNSA under contract DE-AC04-94AL85000.
12:30 PM - SM7.8.08
Electrocoagulation Driven Fabrication of Graphene Oxide Films for Membrane Applications
Clovis Weisbart 1 , Srini Raghavan 1 , Krishna Muralidharan 1 , Barrett Potter 1
1 , University of Arizona, Tucson, Arizona, United States
Show AbstractRecently, there has been significant interest in the utilization of graphene oxide (GO) thin films as aqueous filtration membranes. The stability of such films in water appears to be driven by multivalent, cationic metal contaminants that serve as strong cross-linkers between GO platelets. In this context, this work demonstrates the controlled and rapid formation of metal-ion-containing GO membranes with superior mechanical and structural stability as compared to metal-ion free GO films. Specifically, the method employed in this work is based on copper-ion-assisted electrocoagulation (EC) of GO particles on copper electrodes. In this case, the Cu ion is electrochemically evolved from the deposition electrode itself. The key experimental variables explored were the applied voltage (2-10V), the GO suspension concentration (3-15 mg/mL), and the deposition time (10 seconds-1 minute). The resulting films were characterized by Raman Spectroscopy, X-ray Diffraction, X-ray Photoelectron Spectroscopy, Inductively Coupled Plasma Mass Spectroscopy, and Atomic Force Microscopy to gain information on composition, thickness, morphology, and surface coverage. This unique deposition approach can be extended to other metal substrates, opening up new avenues for employing GO in a wide variety of energy and membrane applications.
12:45 PM - SM7.8.09
Ionomigratively Pumped Salt Micro/Nanolenses along a Cation-Specific 1D Nanochannel
Yun-tae Kim 1 , Chang Young Lee 1
1 , Ulsan National Institute of Science and Technology, Ulsan Korea (the Republic of)
Show AbstractA micro/nanolens of hygroscopic salt with tunable refractive indices provides unique opportunities in molecular spectroscopy and nanotechnology. Forming salt lenses and arranging them in a well-defined manner, however, has been challenging. Here we demonstrate that the exterior of single-walled carbon nanotubes (SWNTs) is a cation-specific 1D nanochannel, which facilitates formation of such lenses via ionomigration driven by momentum transfer from ion flux under electric field. Ionomigration is assisted by strong cation-π interaction, enabling spatiotemporally non-uniform transport of charges along SWNTs. The lens is stable in ambient conditions indefinitely, non-invasively amplifies Raman scattering of various molecular species and SWNTs, by up to two orders of magnitude, optically visualizes individual nanotubes, and can be easily rinsed off. The cation-specific 1D channel has broad implications in spectroscopy, charge-specific chemistry in 1D space, single-molecule transport and detection, and novel charge storage devices.