The Experts below are selected from a list of 22545 Experts worldwide ranked by ideXlab platform
Jung-hyun Lee - One of the best experts on this subject based on the ideXlab platform.
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High-performance and acid-resistant nanofiltration membranes prepared by Solvent Activation on polyamide reverse osmosis membranes
Journal of Membrane Science, 2020Co-Authors: Min Gyu Shin, Soon Jin Kwon, Hosik Park, You-in Park, Jung-hyun LeeAbstract:Abstract We present a facile method for fabricating polyamide (PA) nanofiltration (NF) membranes exhibiting remarkable separation performance and high acid stability via Solvent Activation on PA reverse osmosis (RO) membranes with strong polar aprotic Solvents (dimethyl sulfoxide (DMSO), dimethylformamide and N-methyl-2-pyrrolidone). The Solvents with strong solvency power for PA greatly swelled and deformed the dense RO PA layer, making the PA network more permeable and looser, which significantly improved the water permeance of the RO membrane while maintaining its high rejection to divalent salts. Consequently, the Solvent-activated RO membranes exhibited remarkable NF-grade separation performance, exceeding that of the commercial NF membrane (NF270, Dow Filmtec.). Particularly, the DMSO-activated membrane showed ∼30% higher water permeance, higher salt rejection and ∼6.8 times higher monovalent/divalent ion selectivity than NF270. This was attributed to the strongest solvency power of DMSO among the Solvents used. Moreover, the Solvent-activated membrane exhibited the superior acid stability to NF270 owing to the higher acid resistance of its fully-aromatic PA chemistry than that of the semi-aromatic PA. Our proposed method is a simple, effective and commercially viable strategy for fabricating high-performance and acid-resistant NF membranes that can expand the application spectrum of NF technology.
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Facile performance enhancement of reverse osmosis membranes via Solvent Activation with benzyl alcohol
Journal of Membrane Science, 2019Co-Authors: Min Gyu Shin, Sang Hee Park, Soon Jin Kwon, Hyo Eun Kwon, Jong Bae Park, Jung-hyun LeeAbstract:Abstract We present a facile method to enhance separation performance of polyamide (PA) reverse osmosis (RO) membranes via Solvent Activation with a new type of organic Solvent, benzyl alcohol (BA). Activation with BA remarkably improved water permeance (up to ∼140% increase) while maintaining high NaCl rejection (∼99.6%) of the pristine RO membrane, thereby overcoming the flux-rejection trade-off limitation. Thus, the water permeance and permselectivity of the BA-activated RO membrane significantly exceeded those of commercial RO membranes. This significant performance enhancement was attributed to the appropriate solvency power of BA (determined based on Hansen solubility parameters), which led to the balanced structural deformation of the PA selective layer; BA Activation produced a less dense and highly permeable PA structure by greatly swelling PA, while simultaneously healing loosened sites via structural compaction of the PA network with a sufficiently reduced modulus. Based on the Activation results with various organic Solvents ranging from mild to strong Solvents, we propose a more reliable predictor of the Solvent Activation effect. Our strategy is a simple, effective and commercially viable method to enhance RO membrane performance. Additionally, our study highlights on the underlying Solvent activating mechanism of PA RO membranes.
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Overcoming the permeability-selectivity trade-off of desalination membranes via controlled Solvent Activation
Journal of Membrane Science, 1Co-Authors: Min Gyu Shin, Jin Young Seo, Hosik Park, You-in Park, Jung-hyun LeeAbstract:Abstract Here, we present a facile Solvent Activation method for significantly enhancing the desalination performance of reverse osmosis (RO) membranes. Polyamide (PA)-thin film composite (TFC) RO membranes were activated with a dimethyl sulfoxide (DMSO)/water mixture, whose solvency power was carefully controlled by adjusting the DMSO volume fraction. A DMSO/water mixture with a DMSO volume fraction of 0.3 effectively activated the PA selective layer while marginally deforming the polysulfone support of the lab-made PA-TFC membrane, thus considerably enhancing its water permeance by ∼43% while maintaining its NaCl rejection (∼99.4%). All the commercial membranes activated with the optimized DMSO/water Activation protocol also exhibited dramatically enhanced water permeance (26–155%) with unchanged or even higher NaCl rejection, surpassing the conventional permeability–selectivity trade-off. A careful characterization of the structures and properties of the model PA film under various Solvent environments revealed the thermodynamics and kinetics associated with the Activation-induced structural deformation of the PA network, which governs its structural density, consequently affecting the separation properties of the membrane. Our strategy provides a commercially viable means for the fabrication of high-performance membranes together with shedding light on the underlying the structure-property relationship of polymeric membranes.
Congjie Gao - One of the best experts on this subject based on the ideXlab platform.
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Solvent Activation before heat-treatment for improving reverse osmosis membrane performance
Journal of Membrane Science, 2020Co-Authors: Mengqi Shi, Wentao Yan, Chenxi Dong, Lifen Liu, Shijie Xie, Congjie GaoAbstract:Abstract In this work, a novel and simple strategy, i.e., Solvent Activation before heat-treatment was proposed to improve reverse osmosis (RO) membrane performance. This Activation strategy is different from that adopted in previous reports. With this strategy, Solvent Activation was conducted before heat-treatment. While in previous reports, Solvent Activation was conducted after heat-treatment. By systematic characterization, Solvent Activation before and after heat-treatment were compared for the first time. The results showed that exchanging the order of Solvent Activation and heat-treatment created completely different effects on the RO membrane structures and performance. Specifically, Solvent Activation before heat-treatment affected the RO membrane structures more obviously and was superior in terms of improving RO membrane performance. Besides, the Solvent Activation was discussed deeply. The results showed that it had better choose an Activation Solvent, which is non-polar and low viscous as well as molecular size is small. By using an appropriate Activation Solvent, such as hexane, Solvent Activation before heat-treatment improved the RO membrane performance markedly: the flux was improved from 46 ± 1 L m−2· h−1 to 75 ± 5 L m−2 h−1 (by 63%) and meanwhile a high rejection of 98.97 ± 0.08% was retained (the testing condition: 15.5 bar pressure, 2000 ppm NaCl feed and 25 °C). Additionally, an unexpected phenomenon was found: increasing the Activation time led to the decrease of flux and increase of rejection, which is because more Activation Solvent (hexane) molecules remained in the polyamide layer and then impeded the transport of water and salt.
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Graphene Quantum Dots-Doped Thin Film Nanocomposite Polyimide Membranes with Enhanced Solvent Resistance for Solvent-Resistant Nanofiltration
ACS Applied Materials & Interfaces, 2019Co-Authors: Song Xiaojuan, Babul Prasad, Xueli Gao, Bishnupada Mandal, Congjie GaoAbstract:The core of the organic Solvent nanofiltration (OSN) technology is Solvent-resistant nanofiltration (SRNF) membranes. Till now, relative poor performance of Solvent resistance is still the bottleneck of industrial application of SRNF membranes. This work reports a novel polyimide (PI)-based thin-film nanocomposite (TFN) membrane which was embedded with graphene quantum dots (GQDs) and showed an improved Solvent resistance for OSN application. This kind of SRNF membrane, termed (PI-GQDs/PI)XA, was synthesized via serial processes of interfacial polymerization (IP), imidization, cross-linking, and Solvent Activation. The IP process was performed between an aqueous m-phenylenediamine solution doped with GQDs, having an average size of 1.9 nm, and an 1,2,4,5-benzenetetracarboxylic acyl chloride n-hexane solution on the PI substrate surface. The prepared (PI-GQDs-50/PI)X SRNF membranes without organic Solvent Activation achieved an ethanol permeance of nearly 50% higher than those of the GQD-free membranes under the same preparation conditions, while no compromise of the dye rejection was observed. Further, after the Solvent Activation using N, N-dimethylformamide (DMF) at 80 °C for 30 min, the ethanol permeance achieved about an 8-folds increment, from 2.84 to 22.6 L m-2 h-1 MPa-1. Interestingly, the rejection of rhodamine B also increased from 97.8 to 98.6%. A long-term permeation test of more than 100 h using rose bengal (RB, 1017 Da)/DMF solution at room temperature demonstrated that the synthesized (PI-GQDs-50/PI)XA membranes could maintain the DMF permeance and the RB rejection as high as 18.3 L m-2 h-1 MPa-1 and 99.9%, respectively. Moreover, the immersion test of the prepared (PI-GQDs-50/PI)XA SRNF membranes in both DMF and ethanol at room temperature for about one year also demonstrated the long-term organic Solvent stability, indicating their good potential for OSN application.
Ivo F.j. Vankelecom - One of the best experts on this subject based on the ideXlab platform.
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Crosslinked PVDF-membranes for Solvent resistant nanofiltration
Journal of Membrane Science, 2018Co-Authors: Matthias Mertens, Cédric Van Goethem, Marloes Thijs, Guy Koeckelberghs, Ivo F.j. VankelecomAbstract:Abstract Crosslinked poly(vinylidene difluoride) (PVDF) nanofiltration membranes were prepared and tested for Solvent resistant nanofiltration (SRNF) and Solvent tolerant nanofiltration (STNF, i.e. in Solvent/water media) applications. The performance of the membranes was assessed by filtering ethanol (EtOH), iso-propanol (iPrOH), acetonitrile (ACN), dimethylformamide (DMF) or toluene (Tol) solutions containing Rose Bengal (RB), a 1017 Da solute. During these consecutive filtrations, the membranes displayed a Solvent Activation effect which was characterised by TEM, ATR-FTIR and via intermediate EtOH filtrations. This Solvent Activation resulted in a more permeable membrane (by a factor of 11), without loss in retention. Drying the membranes from MeOH resulted in a further increase of the RB retention in ACN and Tol to 98%. The stability of the membranes was characterised using SEM, weight loss analysis and ATR-FTIR. In STNF, a 99% RB retention was achieved from a 1:4 DMF/water mixture.
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Efficient synthesis of interfacially polymerized membranes for Solvent resistant nanofiltration
Journal of Membrane Science, 2015Co-Authors: Sanne Hermans, Guy Koeckelberghs, Elke Dom, Hanne Mariën, Ivo F.j. VankelecomAbstract:Abstract Thin film composite (TFC) membranes are used worldwide in aqueous applications. They mostly consist of a polyamide top-layer put on a polysulfone support via interfacial polymerization. Due to their thin and dense selective layer, these membranes are also interesting for filtrations in organic solutions. Polysulfone should then be replaced by a more Solvent resistant material. The synthesis of Solvent resistant nanofiltration TFC membranes via a newly developed method is reported: phase inversion, crosslinking and impregnation of a polyimide support are combined by adding amines to the aqueous coagulation bath. Next, a thin polyamide top-layer is formed on the support via interfacial polymerization. Several amines are tested as crosslinker for the support and as monomer for top-layer formation. The use of an amine mixture is also explored. Membrane stability, time in the coagulation bath, effect of Solvent Activation and mass and Solvent intensity of the process are investigated. This novel synthesis method minimizes the use of (hazardous) materials, thus requires less reagents and creates less waste. Moreover, time and effort are saved during the synthesis process, which is of great interest for membrane producers and from an environmental point of view.
Peter B. Hitchcock - One of the best experts on this subject based on the ideXlab platform.
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Samarium(III) Pentalene Sandwich Compounds [Sm(η8-C8H4{SiiPr3-1,4}2)(Cp*)] and [Sm(η8-C8H4{SiiPr3-1,4}2)(η5-C8H5{SiiPr3-1,4}2)] and a Mixed-Valence Hexasamarium Cluster Derived from Sm(II)-Based Solvent Activation
Organometallics, 2008Co-Authors: Owen T. Summerscales, David R. Johnston, F. Geoffrey N. Cloke, Peter B. HitchcockAbstract:The reaction of the pentalene salt C8H4{(SiPr3)-Pr-i-1,4}(2)[K](2) with [SmCp*(mu-I)(THF)(2)](2) yields not the expected Sm(II) pentalene-bridged dimer but the Sm(III) sandwich complexes [Sm(eta(8)-C8H4{(SiPr3)-Pr-i-1,4}(2))(eta(5)-Cp*)] (1) and [Sm(eta(8)-C8H4{(SiPr3)-Pr-i-1,4}(2))(eta(5)-C8H5{(SiPr3)-Pr-i-1,4}(2))] (2) and the mixed-valence cluster [Cp*Sm-6(6)(OMe)(8)O][K(THF)(6)] (3) via Solvent Activation of THF. The samarium(III) sandwich compound 2 incorporates an eta(8)-pentalene ligand and an eta(5)-hydropentalenyl ligand. X-ray crystallography shows the Sm(II)/Sm(III) mixed-valence cluster compound 3 to contain a centrosymmetric hexanuclear array of Cp*Sm units, bridged by face-centered mu(3)-methoxy groups, with a central oxo unit.
Min Gyu Shin - One of the best experts on this subject based on the ideXlab platform.
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High-performance and acid-resistant nanofiltration membranes prepared by Solvent Activation on polyamide reverse osmosis membranes
Journal of Membrane Science, 2020Co-Authors: Min Gyu Shin, Soon Jin Kwon, Hosik Park, You-in Park, Jung-hyun LeeAbstract:Abstract We present a facile method for fabricating polyamide (PA) nanofiltration (NF) membranes exhibiting remarkable separation performance and high acid stability via Solvent Activation on PA reverse osmosis (RO) membranes with strong polar aprotic Solvents (dimethyl sulfoxide (DMSO), dimethylformamide and N-methyl-2-pyrrolidone). The Solvents with strong solvency power for PA greatly swelled and deformed the dense RO PA layer, making the PA network more permeable and looser, which significantly improved the water permeance of the RO membrane while maintaining its high rejection to divalent salts. Consequently, the Solvent-activated RO membranes exhibited remarkable NF-grade separation performance, exceeding that of the commercial NF membrane (NF270, Dow Filmtec.). Particularly, the DMSO-activated membrane showed ∼30% higher water permeance, higher salt rejection and ∼6.8 times higher monovalent/divalent ion selectivity than NF270. This was attributed to the strongest solvency power of DMSO among the Solvents used. Moreover, the Solvent-activated membrane exhibited the superior acid stability to NF270 owing to the higher acid resistance of its fully-aromatic PA chemistry than that of the semi-aromatic PA. Our proposed method is a simple, effective and commercially viable strategy for fabricating high-performance and acid-resistant NF membranes that can expand the application spectrum of NF technology.
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Facile performance enhancement of reverse osmosis membranes via Solvent Activation with benzyl alcohol
Journal of Membrane Science, 2019Co-Authors: Min Gyu Shin, Sang Hee Park, Soon Jin Kwon, Hyo Eun Kwon, Jong Bae Park, Jung-hyun LeeAbstract:Abstract We present a facile method to enhance separation performance of polyamide (PA) reverse osmosis (RO) membranes via Solvent Activation with a new type of organic Solvent, benzyl alcohol (BA). Activation with BA remarkably improved water permeance (up to ∼140% increase) while maintaining high NaCl rejection (∼99.6%) of the pristine RO membrane, thereby overcoming the flux-rejection trade-off limitation. Thus, the water permeance and permselectivity of the BA-activated RO membrane significantly exceeded those of commercial RO membranes. This significant performance enhancement was attributed to the appropriate solvency power of BA (determined based on Hansen solubility parameters), which led to the balanced structural deformation of the PA selective layer; BA Activation produced a less dense and highly permeable PA structure by greatly swelling PA, while simultaneously healing loosened sites via structural compaction of the PA network with a sufficiently reduced modulus. Based on the Activation results with various organic Solvents ranging from mild to strong Solvents, we propose a more reliable predictor of the Solvent Activation effect. Our strategy is a simple, effective and commercially viable method to enhance RO membrane performance. Additionally, our study highlights on the underlying Solvent activating mechanism of PA RO membranes.
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Overcoming the permeability-selectivity trade-off of desalination membranes via controlled Solvent Activation
Journal of Membrane Science, 1Co-Authors: Min Gyu Shin, Jin Young Seo, Hosik Park, You-in Park, Jung-hyun LeeAbstract:Abstract Here, we present a facile Solvent Activation method for significantly enhancing the desalination performance of reverse osmosis (RO) membranes. Polyamide (PA)-thin film composite (TFC) RO membranes were activated with a dimethyl sulfoxide (DMSO)/water mixture, whose solvency power was carefully controlled by adjusting the DMSO volume fraction. A DMSO/water mixture with a DMSO volume fraction of 0.3 effectively activated the PA selective layer while marginally deforming the polysulfone support of the lab-made PA-TFC membrane, thus considerably enhancing its water permeance by ∼43% while maintaining its NaCl rejection (∼99.4%). All the commercial membranes activated with the optimized DMSO/water Activation protocol also exhibited dramatically enhanced water permeance (26–155%) with unchanged or even higher NaCl rejection, surpassing the conventional permeability–selectivity trade-off. A careful characterization of the structures and properties of the model PA film under various Solvent environments revealed the thermodynamics and kinetics associated with the Activation-induced structural deformation of the PA network, which governs its structural density, consequently affecting the separation properties of the membrane. Our strategy provides a commercially viable means for the fabrication of high-performance membranes together with shedding light on the underlying the structure-property relationship of polymeric membranes.