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Menachem Elimelech - One of the best experts on this subject based on the ideXlab platform.
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comparison of organic Fouling Resistance of thin film composite membranes modified by hydrophilic silica nanoparticles and zwitterionic polymer brushes
Journal of Membrane Science, 2017Co-Authors: Chad Small, Menachem ElimelechAbstract:We conducted a comparative study to investigate the efficacies of two different types of highly hydrophilic materials (i.e., silica nanoparticles (SiNPs) and zwitterionic polymers) for antiFouling surface modification of polyamide thin-film composite (TFC) membranes. Dense layers of SiNPs and zwitterionic polymer brushes were grafted on the membrane surfaces via dip-coating with aminosilane-functionalized SiNPs (i.e., SiNP-TFC membrane) and surface-initiated atom-transfer radical-polymerization of sulfobetaine methacrylate (i.e., PSBMA-TFC membrane), respectively. With the same degree of enhancement of surface hydrophilicity and identical surface roughness, the PSBMA-TFC membrane exhibited significantly higher Fouling Resistance than the SiNP-TFC membrane in adsorption tests of proteins and bacteria as well as in forward osmosis (FO) dynamic Fouling experiments using alginate as a model organic foulant. Chemical force microscopy measurements revealed that membrane-foulant electrostatic attraction aggravates organic Fouling of the SiNP-TFC membrane to a certain degree, but the primary Fouling mechanism is the complexation of organic foulants with carboxylic groups on the polyamide membrane surface. We attribute the lower Fouling Resistance of the SiNP-TFC membrane to the high density of surface carboxylic groups that may still be accessible to foulants as well as to membrane-foulant electrostatic interaction. On the contrary, the zwitterionic polymer brushes effectively shield the surface carboxylic groups and provide steric hindrance against foulant adsorption due to significant hydration of the zwitterionic brushes.
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post fabrication modification of forward osmosis membranes with a poly ethylene glycol block copolymer for improved organic Fouling Resistance
Journal of Membrane Science, 2015Co-Authors: Devin L Shaffer, Humberto Jaramillo, Santiago Romerovargas Castrillon, Xinglin Lu, Menachem ElimelechAbstract:Abstract Facile and effective strategies are needed to modify forward osmosis (FO) membranes for improved Resistance to organic Fouling. Fouling resistant FO membranes will advance the commercial implementation of FO for treating feed waters with high Fouling potential, such as wastewater and brines. We report a membrane modification technique for post-fabrication grafting of a poly(ethylene glycol) (PEG) block copolymer to the surface of commercial thin-film composite (TFC) FO membranes via an amide coupling reaction. The PEG concentration for membrane modification is optimized based on increased membrane hydrophilicity and reduced water permeability that result from increasing PEG concentrations during modification. Modified membranes exhibit improved Resistance to organic Fouling compared to unmodified control membranes when exposed to an aggressive synthetic wastewater mixture. The Fouling Resistance is achieved despite the non-uniform grafting of PEG, which is attributed to the limited accessibility of carboxylic group binding sites on the membrane surface. The Fouling Resistance of membranes modified using this post-fabrication technique compares favorably to TFC-FO membranes modified using other procedures. The modification technique we report in this work has the advantages of being relatively inexpensive, easy to implement, and applicable to commercial membranes.
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in situ surface chemical modification of thin film composite forward osmosis membranes for enhanced organic Fouling Resistance
Environmental Science & Technology, 2013Co-Authors: Xinglin Lu, Devin L Shaffer, Santiago Romerovargas Castrillon, Menachem ElimelechAbstract:Forward osmosis (FO) is an emerging membrane-based water separation process with potential applications in a host of environmental and industrial processes. Nevertheless, membrane Fouling remains a technical obstacle affecting this technology, increasing operating costs and decreasing membrane life. This work presents the first fabrication of an antiFouling thin-film composite (TFC) FO membrane by an in situ technique without postfabrication treatment. The membrane was fabricated and modified in situ, grafting Jeffamine, an amine-terminated poly(ethylene glycol) derivative, to dangling acyl chloride surface groups on the nascent polyamide active layer. Surface characterization by contact angle, Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), zeta potential, atomic force microscopy (AFM), and fluorescence microscopy, confirms the presence of Jeffamine on the membrane surface. We demonstrate the improved Fouling Resistance of the in situ modified membranes through...
Harshad R. Patel - One of the best experts on this subject based on the ideXlab platform.
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chemically treated polyethersulfone polyacrylonitrile blend ultrafiltration membranes for better Fouling Resistance
Desalination, 2008Co-Authors: A.v.r. Reddy, Harshad R. PatelAbstract:Abstract Membranes with high permeation combined with high rejection rate and high Fouling Resistance are in high demand in market. The stability of membrane is necessary in aqueous applications for separation of biological products such as proteins. Polyethersulfone (PES) is hydrophobic material hence it fouls rapidly during aqueous biological and macromolecular solute separations. Membrane with hydrophilic characteristics have drawn considerable attention in practical use in recent years because of its better Fouling Resistance. This paper is an attempt to prepare hydrophilic PES membranes by blending polyethersulfone (PES) and polyacrylonitrile (PAN) in dimethylformamide (DMF) solvent in different proportions. Blend ultrafiltration membranes of PES and PAN were prepared on non-woven polyester fabric using motor driven prototype membrane casting machine according to phase inversion method. It has been observed that these membranes foul rapidly during ultrafiltration of macromolecular solutes. To improve Fouling Resistance membrane surfaces modified by treatment with aqueous alkali solutions of different concentration at room temperature. Unmodified and modified membranes were characterized using aqueous solution of inorganic solutes (NaCl & Na 2 SO 4 ) and organic solutes (polyethyleneglycol [PEG], dextran [DXT], poly (sodium 4-styrene sufonate) [PSSA]). Modified membrane had shown high flux recovery ratio compared to unmodified membranes, this improvement in the Fouling Resistance is due to hydrophilicity of membrane surface. Hydrophilicity was confirmed by advanced contact angle using DATA Physics direct contact angle tensiometer. Compatibility ofpolymer blends was confirmed by measuring glass transition temperature using differential scanning calorimetry (DSC). For measurement of rejection of macromolecular solutes gel permeation chromatography was used.
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Chemically treated polyethersulfone/polyacrylonitrile blend ultrafiltration membranes for better Fouling Resistance
Desalination, 2008Co-Authors: A.v.r. Reddy, Harshad R. PatelAbstract:Membranes with high permeation combined with high rejection rate and high Fouling Resistance are in high demand in market. The stability of membrane is necessary in aqueous applications for separation of biological products such as proteins. Polyethersulfone (PES) is hydrophobic material hence it fouls rapidly during aqueous biological and macromolecular solute separations. Membrane with hydrophilic characteristics have drawn considerable attention in practical use in recent years because of its better Fouling Resistance. This paper is an attempt to prepare hydrophilic PES membranes by blending polyethersulfone (PES) and polyacrylonitrile (PAN) in dimethylformamide (DMF) solvent in different proportions. Blend ultrafiltration membranes of PES and PAN were prepared on non-woven polyester fabric using motor driven prototype membrane casting machine according to phase inversion method. It has been observed that these membranes foul rapidly during ultrafiltration of macromolecular solutes. To improve Fouling Resistance membrane surfaces modified by treatment with aqueous alkali solutions of different concentration at room temperature. Unmodified and modified membranes were characterized using aqueous solution of inorganic solutes (NaCl & Na2SO4) and organic solutes (polyethyleneglycol [PEG], dextran [DXT], poly (sodium 4-styrene sufonate) [PSSA]). Modified membrane had shown high flux recovery ratio compared to unmodified membranes, this improvement in the Fouling Resistance is due to hydrophilicity of membrane surface. Hydrophilicity was confirmed by advanced contact angle using DATA Physics direct contact angle tensiometer. Compatibility ofpolymer blends was confirmed by measuring glass transition temperature using differential scanning calorimetry (DSC). For measurement of rejection of macromolecular solutes gel permeation chromatography was used. © 2008.
Sara Azari - One of the best experts on this subject based on the ideXlab platform.
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coating zwitterionic amino acid l dopa to increase Fouling Resistance of forward osmosis membrane
Desalination, 2013Co-Authors: Anh V Nguyen, Sara AzariAbstract:Abstract In this study, the HTI Forward Osmosis (FO) membrane surfaces were modified by the deposition of poly amino acid 3-(3,4-Dihydroxyphenyl)- l -alanine ( l -DOPA), a zwitterionic polymer on the membrane surface in order to enhance the Fouling Resistance of the FO membranes. The modification took place on the porous layer/side of the membranes. The modified membrane surfaces became more hydrophilic with a reduced initial water contact angle. Accelerated Fouling experiments were conducted in pressure retarded osmosis (PRO) mode, in which the porous layer of membrane faced the feed solution. The feed solution comprised alginic acid sodium salt (AAS) and calcium ions (CaCl2). The filtration results proved an effective improvement of Fouling Resistance of the l -DOPA coated membranes. The membrane samples with a 12-hour coating achieved 30% less Fouling compared to the uncoated sample. The l -DOPA coating method is simple and direct; it has the potential for scaled up industrial applications.
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using zwitterionic amino acid l dopa to modify the surface of thin film composite polyamide reverse osmosis membranes to increase their Fouling Resistance
Journal of Membrane Science, 2012Co-Authors: Sara AzariAbstract:Abstract This study focuses on the incorporation of redox functional amino acid 3-(3,4-dihydroxyphenyl)- l -alanine ( l -DOPA) onto commercial reverse osmosis (RO) membranes (SW 30 XLE) to create a zwitterionic surface that resists membrane Fouling. The top layer of the membranes surfaces was modified by the deposition of l -DOPA from its alkaline solution. Streaming potential and contact angle measurements were conducted to characterise the membrane surface. Zeta potential data showed little or no change in the surface charge of 24-h-coated membrane relative to the original membrane. The contact angle measurements indicated that the hydrophilicity of the coated membranes was significantly improved. UV–visible spectroscopy confirmed the presence of poly DOPA film on the coated membranes. Whilst the salt rejection remained unchanged, a systematic increase in water flux was observed for the samples coated up to 12 h. Static BSA adhesion experiments revealed that l -DOPA coating has reduced the amount of BSA adsorbed to the surface. To investigate the dynamic Fouling Resistance of the membranes, a series of cross-flow filtration tests were carried out using bovine serum albumin (BSA) and alginic acid sodium salt solution as the feed. The modified membranes exhibited less flux decline than the original untreated membrane. Further, by water-only cleaning 98% water flux recovery ratio was achieved for the 24-h-modified membrane. The coated membranes also showed an improvement in their Fouling Resistance when testing with the solution containing dodecyltrimethyl ammonium bromide (DTAB), a positively charged surfactant model foulant.
Sanchuan Yu - One of the best experts on this subject based on the ideXlab platform.
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In situ modification of polyamide reverse osmosis membrane module for improved Fouling Resistance
Chemical Engineering Research & Design, 2018Co-Authors: Chuang Yu, Zhenhua Lü, Yiyang Wu, Sanchuan YuAbstract:Abstract In situ improvement of Fouling Resistance of the state-of-the-art polyamide reverse osmosis membrane module on the basis of the Fouling characteristic of the fluid to be treated is of great practical significance. In this work, in situ modification was performed with the spiral wound polyamide reverse osmosis membrane module for improved Fouling Resistance to specific foulant. Small molecular monomers of amidosulfonic acid (ASA), diethanolamine (DEA) and piperazine (PIP) were grafted onto the surface of the flat-sheet polyamide-based thin-film composite membrane within the module separately through 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-activated amidation of carboxyl groups. The results of Fouling experiments indicated that the Fouling Resistance of the polyamide reverse osmosis membrane module to the model foulants of bovine serum protein (BSA), sodium alginate (SA) and dodecyl trimethyl ammonium bromide (DTAB) could be effectively improved through grafting monomers ASA, DEA and PIP, respectively, showing significant reduction in declines of membrane flux to aqueous BSA, SA and DTAB solutions by 47.2%, 41.3% and 34.4%. The changes of membrane surface hydrophilicity and negative charge were in charge of the improved antiFouling property. The in-situ modification was also found to slightly enhance membrane salt rejection and have nearly no influence on membrane water flux.
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Enhanced both perm-selectivity and Fouling Resistance of poly(piperazine-amide) nanofiltration membrane by incorporating sericin as a co-reactant of aqueous phase
Journal of Membrane Science, 2017Co-Authors: Runping Xu, Zhenhua Lü, Sanchuan YuAbstract:This study focuses on the fabrication of flat-sheet thin-film composite poly(piperazine-amide)-based nanofiltration membrane with enhanced both perm-selectivity and Fouling Resistance. Sericin was used as the co-reactant of piperazine (PIP) to form the selective skin layer through the interfacial reaction with trimesoyl chloride (TMC) on the surface of polysulfone porous support. Membranes prepared with different contents of sericin were rigorously characterized to investigate the effects of the incorporation of sericin on membrane physico-chemical and permeation properties. ATR-FTIR and EDX analyses confirmed the incorporation of sericin in the formed active layer, which was found to significantly enhance membrane water flux through enlarging membrane pore size and increasing surface hydrophilicity while maintaining Na2SO4 rejection through intensifying electrostatic repulsion effect. Membranes with both enhanced water permeability and solute selectivity could be prepared through controlling the content of sericin. For instance, by adding 0.06%(w/v) of sericin into the PIP-aqueous solution, the pure water permeability was enhanced by 36.7%, the Na2SO4 rejection was remained as high as 97.5% of the PIP-TMC membrane, and the selectivity to mixed NaCl/Na2SO4 solution was increased from 21.2 to 25.2. Moreover, the incorporation of sericin was also found to endow the membrane with improved Fouling Resistance to bovine serum albumin.
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improving Fouling Resistance of thin film composite polyamide reverse osmosis membrane by coating natural hydrophilic polymer sericin
Separation and Purification Technology, 2013Co-Authors: Sanchuan Yu, Bingyan Dong, Xiangyang PengAbstract:Abstract In this study, a commercial thin-film composite aromatic polyamide reverse osmosis membrane was modified through coating a surface layer of natural polymer sericin for improved antiFouling property. The deposition of sericin on the membrane was carried out through dip-coating followed by in situ cross-linking and was confirmed by ATR-FTIR spectroscopy. The changes of surface charge, hydrophilicity and roughness that resulted from the sericin application were analyzed using zeta-potential analysis, contact angle measurement and atomic force microscopy, respectively. The separation performance was evaluated through cross-flow permeation tests. It was found that the sericin-coated membrane showed improved surface hydrophilicity, enhanced surface negative charge, smoothed surface morphology, and decreased pure water permeability and salt permeability coefficient. The results of Fouling experiments with bovine serum albumin aqueous solution revealed that the Fouling Resistance of the reveres osmosis membrane could be effectively improved by coating sericin surface layer. Although the initial flux of the modified membrane was lower than that of the unmodified membrane under the same operating pressure due to the additional hydraulic Resistance, the rate of flux decline slowed after modification due to the mitigation of foulant deposition on the membrane surface and compensated for the initial flux decline within 40 h.
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surface modification of thin film composite polyamide membranes by electrostatic self deposition of polycations for improved Fouling Resistance
Separation and Purification Technology, 2009Co-Authors: Yong Zhou, Sanchuan Yu, Xianshe FengAbstract:Abstract Interfacially polymerized polyamide thin film composite membrane was modified by electrostatic self-assembly of polyethyleneimine on the membrane surface, and the modified membrane showed significantly improved antiFouling properties. The charge reversal on the membrane surface due to the application of the polyethyleneimine layer was shown to increase the Fouling Resistance of the membrane to cationic foulants because of the enhanced electrostatic repulsion, and the increased surface hydrophilicity would help minimize the flux reduction. The effects of parameters involved in the membrane surface modification (e.g., polyethyleneimine concentration and deposition time) on the membrane performance were investigated in terms of water permeation flux and salt rejection. The membrane modification was found to increase salt rejections when MgCl 2 and NaCl were tested. The Fouling behavior of the membranes was also studied with and without the presence of dodecyltrimethylammonium bromide (which is a common cationic surfactant present in waste water). It was shown that while the deposited polyethyleneimine surface layer tended to offer additional Resistance to permeation, the improved Fouling Resistance and the increased surface hydrophilicity compensated for the reduction in membrane permeability due to the deposition of the polyethyleneimine layer.
Tao He - One of the best experts on this subject based on the ideXlab platform.
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Fouling Resistance of 3 3 trimethoxysilane propyl amino propane 1 sulfonic acid zwitterion modified poly vinylidene fluoride membranes
Separation and Purification Technology, 2020Co-Authors: Wentao Zhai, Xuemei Li, Mengliang Wang, Jianfeng Song, Lin Zhang, Tao HeAbstract:Abstract Zwitterion polymer modified membranes have demonstrated Fouling Resistance in wide applications. The ubiquitous success in scientific progress, however, has not yet brought significant breakthrough in the application of such membranes in wastewater treatment. Limitation of zwitterion materials in membrane is seldomly discussed. In this paper, we aimed to bring an engineering view on the pros-and-cons of zwitterion modified microfiltration membrane in treating solutions containing humic acid (HA) and bovine serum albumin (BSA). A 3-[[3-(trimethoxysilane)-propyl] amino] propane-1-sulfonic acid (TMAPS) grafted zwitterionic PVDF membrane was selected as a model membrane. The membranes were prepared via a two-step “hydroxylation-grafting” method; surface modified PVDF membrane was transformed from hydrophobic to hydrophilic with significant improvement in pure water flux. An 87% increase was obtained in the stable flux for the grafted membrane when treating HA, but very similar flux pattern to the pristine one was found when treating BSA. The membrane Resistance model showed that cake layer was the main Fouling factor for both foulants. For HA, the cake layer blocking model predicted the membrane flux well; but for BSA, the intermediate blocking model fits best the experimental results. Zwitterion grafted surface failed to show improvement in the Fouling Resistance even at very low BSA feed concentration. Adsorption experiment indicated that the interaction of BSA to membrane is significantly stronger than HA and membranes independent from the surface characteristics. Present work clarified the limitation of zwitterion modified membranes in treating solutions containing HA-like and protein matters.
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unprecedented scaling Fouling Resistance of omniphobic polyvinylidene fluoride membrane with silica nanoparticle coated micropillars in direct contact membrane distillation
Journal of Membrane Science, 2020Co-Authors: Zechun Xiao, Hailong He, Xuemei Li, Yuebiao Zhang, A V Volkov, Tao HeAbstract:Abstract Recent development of omniphobic membranes shows promise in scaling/Fouling mitigation in membrane distillation (MD), however, the fundamental understanding is still under dispute. In this paper, we report a novel omniphobic micropillared membrane coated by silica nanoparticles (SiNPs) (SiNPs-MP-PVDF) with dual-scale roughness prepared by a micromolding phase separation (μPS) and electrostatic attraction. This membrane was used as a model for analysis of scaling behavior by calcium sulfate (CaSO4) scaling and Fouling behavior by protein casein in comparison with commercial (C-PVDF) and micropillared (MP-PVDF) membranes. Unprecedented scaling/Fouling Resistance to CaSO4 and casein was observed in direct contact membrane distillation (DCMD) for SiNPs-MP-PVDF membrane. Similar scaling and Fouling occurred for commercial PVDF and micropillared PVDF membranes. The observation corresponds well to the wetting state of all membranes as SiNPs-MP-PVDF shows suspended wetting, but MP-PVDF shows pinned wetting. From a hydrodynamic view, the suspended wetting attributes a slippery surface which reduces the direct contact of foulants to solid membrane part and leads to significantly reduced Fouling and scaling. However, a pinned (or metastable) wetting state leads to a stagnant interfacial layer that is prone to severe Fouling and scaling. This work highlights that both scaling and Fouling Resistance are indeed of suspended wetting state and slippage origin.
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Unprecedented scaling/Fouling Resistance of omniphobic polyvinylidene fluoride membrane with silica nanoparticle coated micropillars in direct contact membrane distillation
Journal of Membrane Science, 2020Co-Authors: Zechun Xiao, Hailong He, Xuemei Li, Yuebiao Zhang, Alexey Volkov, Tao HeAbstract:Abstract Recent development of omniphobic membranes shows promise in scaling/Fouling mitigation in membrane distillation (MD), however, the fundamental understanding is still under dispute. In this paper, we report a novel omniphobic micropillared membrane coated by silica nanoparticles (SiNPs) (SiNPs-MP-PVDF) with dual-scale roughness prepared by a micromolding phase separation (μPS) and electrostatic attraction. This membrane was used as a model for analysis of scaling behavior by calcium sulfate (CaSO4) scaling and Fouling behavior by protein casein in comparison with commercial (C-PVDF) and micropillared (MP-PVDF) membranes. Unprecedented scaling/Fouling Resistance to CaSO4 and casein was observed in direct contact membrane distillation (DCMD) for SiNPs-MP-PVDF membrane. Similar scaling and Fouling occurred for commercial PVDF and micropillared PVDF membranes. The observation corresponds well to the wetting state of all membranes as SiNPs-MP-PVDF shows suspended wetting, but MP-PVDF shows pinned wetting. From a hydrodynamic view, the suspended wetting attributes a slippery surface which reduces the direct contact of foulants to solid membrane part and leads to significantly reduced Fouling and scaling. However, a pinned (or metastable) wetting state leads to a stagnant interfacial layer that is prone to severe Fouling and scaling. This work highlights that both scaling and Fouling Resistance are indeed of suspended wetting state and slippage origin.