The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Toshikatsu Sata - One of the best experts on this subject based on the ideXlab platform.
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studies on Cation Exchange Membranes having permselectivity between Cations in electrodialysis
Journal of Membrane Science, 2002Co-Authors: Toshikatsu Sata, Wongkang YangAbstract:Abstract Recent studies on selective permeation of specific Cations through a Cation-Exchange Membrane in electrodialysis, modifiCation of the Membrane and electrodialysis method, are reviewed. The studies are classified (1) to prepare the composite of the Cation-Exchange Membrane with other polymers such as conducting polymers and Cationic polyelectrolytes, (2) to change Cation-Exchange groups from sulfonic acid groups, which are used in conventional Membranes, to other groups such as phosphonic acid groups, and (3) to electrodialyze the mixed salt solution in the presence of chelate-forming agent such as poly(ethylene glycol), crown ethers, etc. Though the formation of the layers of the conducting polymers on the surface of the Cation-Exchange Membrane is effective on selective permeation of monovalent Cations to divalent Cations through the Membrane, mechanism of the selective permeation is different depending on species of the conducting polymers: due to sieving of sodium ions from multivalent Cations by a tight polypyrrole layer and due to stronger electrostatic repulsion force of the Cationic charge in a polyaniline layer to multivalent Cations than to the monovalent, which is similar to the Membrane having a Cationic polyelectrolyte layer on the surface. When Cation-Exchange groups such as phosphonic acid groups, which are strongly interacted with divalent Cations, are introduced in the Membrane, monovalent Cations selectively permeate through the Membrane. However, current efficiency in electrodialysis decreases due to strong binding of divalent Cations to the groups—inactivation of Cation-Exchange groups. Electrodialysis in the presence of chelate-forming agents is effective on the selective permeation of specific Cations that have low complex formation constants with the agents through the Membrane without any decrease in the current efficiency.
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Properties of composite Membranes prepared from ion Exchange Membranes and conducting polymers. II: Electrical potential generation from cell composed of a Cation Exchange Membrane-polypyrrole composite Membrane and a ferric ion form Cation Exchange
Journal of Membrane Science, 1993Co-Authors: Toshikatsu SataAbstract:Abstract When a ferric ion form Cation Exchange Membrane was immersed in an aqueous pyrrole solution, polypyrrole was formed on the Membrane surfaces and ferric ions in the Membrane were reduced to ferrous ions. Polypyrrole layers penetrated into the Membrane matrix with increasing immersion period in the pyrrole solution. An electrical potential was observed by clamping the obtained composite Membrane and the ferric ion form Cation Exchange Membrane between two platinum plates and immersing the assembly into pure water. The potential was measured in relation to polymerization period. Before homogeneous distribution of polypyrrole in the Membrane (4 hr), which was confirmed by conductivity measurement, an initial potential in discharge decreased and durability of the potential increased with increasing polymerization period. Beyond 4 hr of polymerization in the synthesis of the composite Membrane, the initial potential on discharge attained almost a constant value and its durability decreased with increasing polymerization period in spite of increase in electron conductivity and the amount of ferrous ions in the composite Membrane. It is thought that migration of ferrous ions in the composite Membrane would be restricted because of a development of a tight and rigid polypyrrole structure in the Cation Exchange Membrane.
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Preparation of redox cell properties of Cation Exchange Membrane combined anisotropically with polypyrrole
Journal of Membrane Science, 1992Co-Authors: Toshikatsu SataAbstract:Abstract Trials to produce a Cation Exchange Membrane with anisotropic structure were carried out with Cation Exchange Membranes, pyrrole or aniline, and ferric ions. When one side of a Cation Exchange Membrane of ferric ion form contacted an aqueous pyrrole solution, pyrrole polymerized on only the surface portion of the Membrane to produce an anisotropic structure. Evidently a thin, tight polypyrrole layer, through which pyrrole molecules could not permeate easily, was formed on the Membrane surface. When this composite Membrane was held tightly between two platinum plates, it produced an e.m.f. that was dependent on relative humidity. The e.m.f. was reproducible in wet-dry cycles in air. The e.m.f. seems to have been generated from Fe 2+ -Fe 3+ redox reactions, because ferric ions in the Membrane were reduced to ferrous ions during the polymerization of pyrrole.
Yongsheng Chen - One of the best experts on this subject based on the ideXlab platform.
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fouling resistant nanocomposite Cation Exchange Membrane with enhanced power generation for reverse electrodialysis
Journal of Membrane Science, 2016Co-Authors: Xin Tong, Bopeng Zhang, Yongsheng ChenAbstract:Abstract Renewable energy can be generated from the mixing of seawater with river water by reverse electrodialysis (RED). As part of the RED system, ion Exchange Membranes (IEMs) are key factors to the success of future RED energy generation. This research presents the synthesis and characterization of a new kind of nanocomposite Cation Exchange Membrane (CEM) by using oxidized multi-walled carbon nanotubes (O-MWCNTs) blended with sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO). The nanocomposite CEM showed simultaneous improvement of Membrane anti-fouling performance and energy generation performance in RED systems. The physicochemical and electrochemical properties of nanocomposite CEMs were enhanced compared to pristine SPPO CEMs. The results indicated that the optimal inorganic loadings were 0.3–0.5 wt%, which showed the best anti-fouling performance and highest power density in RED. The results show that O-MWCNTs are promising materials to improve properties of IEMs, and nanocomposite IEMs are competitive candidates for appliCation in electrochemical systems like RED.
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fouling resistant nanocomposite Cation Exchange Membrane with enhanced power generation for reverse electrodialysis
Journal of Membrane Science, 2016Co-Authors: Xin Tong, Bopeng Zhang, Yongsheng ChenAbstract:Abstract Renewable energy can be generated from the mixing of seawater with river water by reverse electrodialysis (RED). As part of the RED system, ion Exchange Membranes (IEMs) are key factors to the success of future RED energy generation. This research presents the synthesis and characterization of a new kind of nanocomposite Cation Exchange Membrane (CEM) by using oxidized multi-walled carbon nanotubes (O-MWCNTs) blended with sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO). The nanocomposite CEM showed simultaneous improvement of Membrane anti-fouling performance and energy generation performance in RED systems. The physicochemical and electrochemical properties of nanocomposite CEMs were enhanced compared to pristine SPPO CEMs. The results indicated that the optimal inorganic loadings were 0.3–0.5 wt%, which showed the best anti-fouling performance and highest power density in RED. The results show that O-MWCNTs are promising materials to improve properties of IEMs, and nanocomposite IEMs are competitive candidates for appliCation in electrochemical systems like RED.
Gérald Pourcelly - One of the best experts on this subject based on the ideXlab platform.
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multistep mineral fouling growth on a Cation Exchange Membrane ruled by gradual sieving effects of magnesium and carbonate ions and its delay by pulsed modes of electrodialysis
Journal of Colloid and Interface Science, 2012Co-Authors: Nicolas Cifuentesaraya, Gérald Pourcelly, Laurent BazinetAbstract:The aim of this study was to reveal the mechanisms ruling a fouling growth on both sides of a CMX-SB Cation-Exchange Membrane (CEM), run after run during three consecutive electrodialysis (ED) treatments. A model solution containing a high magnesium/calcium ratio (2/5) was demineralized under two different pulsed electric field (PEF) on-duty ratios and dc current. The results showed a series of mechanisms ruling a multilayer mineral fouling growth and its delay by PEFs. The nature of the fouling layer, during a first run, depended on the diluate pH-value evolutions and the ion migration rates through the Membrane. A subsequent multilayer fouling growth during consecutive treatments was ruled by the already formed mineral layers, where gradual sieving effects inverted the migration rates and led to a multistep crystal growth. Calcium carbonate grew on the diluate side of CEM, starting from its amorphous phase to then crystallize in a coexisting presence of aragonite and calcite. Amorphous magnesium hydroxide appeared on CEM apparently through fouling dehydration ruled by the mineral layers themselves and by overlimiting current regimes. A delayed fouling growth was observed for PEF ratio 0.3. A long pause lapse during pulse modes was demonstrated as an important parameter for fouling mitigation.
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evolution with time of hydrophobicity and microrelief of a Cation Exchange Membrane surface and its impact on overlimiting mass transfer
Journal of Physical Chemistry B, 2012Co-Authors: N D Pismenskaya, Lasâad Dammak, V V Nikonenko, Gérald Pourcelly, Nadezhda Melnik, Kseniya A Shevtsova, E I Belova, Didier Cot, Christian LarchetAbstract:Surface properties were measured together with electrochemical characteristics of a CMX (Neosepta, Tokuyama Corp.) Cation-Exchange Membrane. Relative hydrophobicity was controlled by the contact angle; XPS and SEM were used for characterizing chemical composition and microrelief of the surface, respectively. Voltammetry, chronopotentiometry, and mass transfer rate measurements were made as well. A “fresh” Membrane and samples after 10, 25, 100, and 150 h of operation in an electrodialysis cell at an overlimiting current equal to 3 theoretical limiting currents, in a 0.02 M NaCl solution, were characterized. Some electrochemical properties were also measured for a Neosepta Cation-Exchange Membrane, aged 2 years, in an industrial food process. It was found that the hydrophobicity of the CMX Membrane has increased after the first 10 h of operation; more and more cavities of the dimension of the order of 1 μm have appeared with time testifying electrochemical erosion of the surface. The limiting current densi...
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electrodialysis of acid effluents containing metallic divalent salts recovery of acid with a Cation Exchange Membrane modified in situ
Journal of Applied Electrochemistry, 1997Co-Authors: Philippe Sistat, Gérald Pourcelly, Claude Gavach, N Turcotte, Mario BoucherAbstract:The recovery of sulfuric acid from effluents containing metallic salts (Mg, Zn, Mn) was achieved by electrodialysis with a Nafion® Cation Exchange Membrane modified in situ by electrodeposition of polyethyleneimine on one side of the Membrane. The purity of the acid obtained depends on the experimental conditions of this electrodeposition. The total metal leakage through the modified Membrane can be lowered to 0.5% with no significant increase in the energy consumption of the process due to a possible increase of the electrical resistance. These results are comparable with, and even better than, those obtained with commercial Membranes specially designed for this type of appliCation. The advantage of this modifiCation process is the possibility of regenerating the surface layer directly in the Membrane stack.
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Chronopotentiometric response of a Cation Exchange Membrane in contact with chromium(III) solutions
Desalination, 1996Co-Authors: M. Taky, Gérald Pourcelly, Claude Gavach, Azzedine ElmidaouiAbstract:Abstract The paper deals with the transfer of ionic species containing Cr III through a CMV Cation-Exchange Membrane. Two electrochemical techniques are used: the chronopotentiometric response and the transport number measurements. According to the composition of the anodic solution containing CrCl 3 , hydroxyl ion-chromium III complex forms enter into the Membrane and water splitting occurs. This phenomenon is attributed to a poisoning of the Membrane by these multivalent complex forms which change locally the selectivity of the Cation-Exchange Membrane.
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Polarization phenomena at the interfaces between an electrolyte solution and an ion Exchange Membrane: Part I. Ion transfer with a Cation Exchange Membrane
Journal of Electroanalytical Chemistry, 1992Co-Authors: M. Taky, Gérald Pourcelly, Frédéric Lebon, Claude GavachAbstract:Abstract Polarization phenomena occurring with ion Exchange Membranes have been investigated for the Selemion AMV anion Exchange Membrane in contact with NACl solutions. Recording of the current density—voltage responses combined with pH measurements and with individual ion flux measurements allow the determination of which phenomena are at the basis of the current transport. The concentration and potential profiles within the depleted unstirred layer have been calculated. Water splitting is indicated beyond the limiting current density. Analysis of the different overvoltages leads to a comparison between the interfacial transfer overvoltages of both the AMV anion Exchange Membrane and the CMV Cation Exchange Membrane.
M A Andreeva - One of the best experts on this subject based on the ideXlab platform.
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effect of homogenization and hydrophobization of a Cation Exchange Membrane surface on its scaling in the presence of calcium and magnesium chlorides during electrodialysis
Journal of Membrane Science, 2017Co-Authors: Lasâad Dammak, Christian Larchet, M A Andreeva, N D Pismenskaya, V V Nikonenko, Daniel Grande, N A KononenkoAbstract:Abstract In this paper, two Cation-Exchange Membranes, i.e. MK-40 and MK-40 MOD , were studied by chronopotentiometry and voltammetry, MK-40 MOD being obtained by covering the heterogeneous surface of a commercial MK-40 Membrane with a homogeneous 20 µm thick Nafion ® film. Electrodialysis process was realized in an electrodialysis flow-through laboratory cell, in which the Cation-Exchange Membrane under study formed a desalination chamber with an auxiliary anion-Exchange (Neosepta AMX-SB) Membrane. 0.02 M and 0.04 M solutions of CaCl 2 , MgCl 2 and NaCl were used. The current densities were changed in the range from 0.25 i lim t h to 2.5 i lim t h , where the theoretical limiting current density, i lim t h , was calculated using the Leveque equation. The potential drop over the modified MK-40 MOD Membrane and the water splitting at this Membrane turned out to be lower in all studied cases. Formation of scaling was observed only in the case of the MK-40/0.04 M MgCl 2 system at current densities in the range from 1.1 i lim t h to 1.4 i lim t h . For these current densities, the (quasi)steady state value of potential drop slowly increased with time and the crystals of Mg(OH) 2 were found on the ion-Exchange particles embedded onto the MK-40 Membrane surface facing the desalination chamber. At higher currents, stronger electroconvection at this Membrane and higher water splitting at the AMX-SB Membrane (the latter providing lower pH in the desalination chamber) prevented scaling. No scaling was found on the modified Membrane at any current. It is due to the Nafion ® film, which is relatively more hydrophobic than pristine MK-40 and which provides a “better” distribution of current lines near the surface, thus enhancing electroconvection and decreasing water splitting.
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effect of homogenization and hydrophobization of a Cation Exchange Membrane surface on its scaling in the presence of calcium and magnesium chlorides during electrodialysis
Journal of Membrane Science, 2017Co-Authors: Lasâad Dammak, Christian Larchet, M A Andreeva, N D Pismenskaya, V V Nikonenko, Daniel Grande, V V Gil, N A KononenkoAbstract:Abstract In this paper, two Cation-Exchange Membranes, i.e. MK-40 and MK-40MOD, were studied by chronopotentiometry and voltammetry, MK-40MOD being obtained by covering the heterogeneous surface of a commercial MK-40 Membrane with a homogeneous 20 µm thick Nafion® film. Electrodialysis process was realized in an electrodialysis flow-through laboratory cell, in which the Cation-Exchange Membrane under study formed a desalination chamber with an auxiliary anion-Exchange (Neosepta AMX-SB) Membrane. 0.02 M and 0.04 M solutions of CaCl2, MgCl2 and NaCl were used. The current densities were changed in the range from 0.25 i lim t h to 2.5 i lim t h , where the theoretical limiting current density, i lim t h , was calculated using the Leveque equation. The potential drop over the modified MK-40MOD Membrane and the water splitting at this Membrane turned out to be lower in all studied cases. Formation of scaling was observed only in the case of the MK-40/0.04 M MgCl2 system at current densities in the range from 1.1 i lim t h to 1.4 i lim t h . For these current densities, the (quasi)steady state value of potential drop slowly increased with time and the crystals of Mg(OH)2 were found on the ion-Exchange particles embedded onto the MK-40 Membrane surface facing the desalination chamber. At higher currents, stronger electroconvection at this Membrane and higher water splitting at the AMX-SB Membrane (the latter providing lower pH in the desalination chamber) prevented scaling. No scaling was found on the modified Membrane at any current. It is due to the Nafion® film, which is relatively more hydrophobic than pristine MK-40 and which provides a “better” distribution of current lines near the surface, thus enhancing electroconvection and decreasing water splitting.
Christian Larchet - One of the best experts on this subject based on the ideXlab platform.
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effect of homogenization and hydrophobization of a Cation Exchange Membrane surface on its scaling in the presence of calcium and magnesium chlorides during electrodialysis
Journal of Membrane Science, 2017Co-Authors: Lasâad Dammak, Christian Larchet, M A Andreeva, N D Pismenskaya, V V Nikonenko, Daniel Grande, V V Gil, N A KononenkoAbstract:Abstract In this paper, two Cation-Exchange Membranes, i.e. MK-40 and MK-40MOD, were studied by chronopotentiometry and voltammetry, MK-40MOD being obtained by covering the heterogeneous surface of a commercial MK-40 Membrane with a homogeneous 20 µm thick Nafion® film. Electrodialysis process was realized in an electrodialysis flow-through laboratory cell, in which the Cation-Exchange Membrane under study formed a desalination chamber with an auxiliary anion-Exchange (Neosepta AMX-SB) Membrane. 0.02 M and 0.04 M solutions of CaCl2, MgCl2 and NaCl were used. The current densities were changed in the range from 0.25 i lim t h to 2.5 i lim t h , where the theoretical limiting current density, i lim t h , was calculated using the Leveque equation. The potential drop over the modified MK-40MOD Membrane and the water splitting at this Membrane turned out to be lower in all studied cases. Formation of scaling was observed only in the case of the MK-40/0.04 M MgCl2 system at current densities in the range from 1.1 i lim t h to 1.4 i lim t h . For these current densities, the (quasi)steady state value of potential drop slowly increased with time and the crystals of Mg(OH)2 were found on the ion-Exchange particles embedded onto the MK-40 Membrane surface facing the desalination chamber. At higher currents, stronger electroconvection at this Membrane and higher water splitting at the AMX-SB Membrane (the latter providing lower pH in the desalination chamber) prevented scaling. No scaling was found on the modified Membrane at any current. It is due to the Nafion® film, which is relatively more hydrophobic than pristine MK-40 and which provides a “better” distribution of current lines near the surface, thus enhancing electroconvection and decreasing water splitting.
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effect of homogenization and hydrophobization of a Cation Exchange Membrane surface on its scaling in the presence of calcium and magnesium chlorides during electrodialysis
Journal of Membrane Science, 2017Co-Authors: Lasâad Dammak, Christian Larchet, M A Andreeva, N D Pismenskaya, V V Nikonenko, Daniel Grande, N A KononenkoAbstract:Abstract In this paper, two Cation-Exchange Membranes, i.e. MK-40 and MK-40 MOD , were studied by chronopotentiometry and voltammetry, MK-40 MOD being obtained by covering the heterogeneous surface of a commercial MK-40 Membrane with a homogeneous 20 µm thick Nafion ® film. Electrodialysis process was realized in an electrodialysis flow-through laboratory cell, in which the Cation-Exchange Membrane under study formed a desalination chamber with an auxiliary anion-Exchange (Neosepta AMX-SB) Membrane. 0.02 M and 0.04 M solutions of CaCl 2 , MgCl 2 and NaCl were used. The current densities were changed in the range from 0.25 i lim t h to 2.5 i lim t h , where the theoretical limiting current density, i lim t h , was calculated using the Leveque equation. The potential drop over the modified MK-40 MOD Membrane and the water splitting at this Membrane turned out to be lower in all studied cases. Formation of scaling was observed only in the case of the MK-40/0.04 M MgCl 2 system at current densities in the range from 1.1 i lim t h to 1.4 i lim t h . For these current densities, the (quasi)steady state value of potential drop slowly increased with time and the crystals of Mg(OH) 2 were found on the ion-Exchange particles embedded onto the MK-40 Membrane surface facing the desalination chamber. At higher currents, stronger electroconvection at this Membrane and higher water splitting at the AMX-SB Membrane (the latter providing lower pH in the desalination chamber) prevented scaling. No scaling was found on the modified Membrane at any current. It is due to the Nafion ® film, which is relatively more hydrophobic than pristine MK-40 and which provides a “better” distribution of current lines near the surface, thus enhancing electroconvection and decreasing water splitting.
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evolution with time of hydrophobicity and microrelief of a Cation Exchange Membrane surface and its impact on overlimiting mass transfer
Journal of Physical Chemistry B, 2012Co-Authors: N D Pismenskaya, Lasâad Dammak, V V Nikonenko, Gérald Pourcelly, Nadezhda Melnik, Kseniya A Shevtsova, E I Belova, Didier Cot, Christian LarchetAbstract:Surface properties were measured together with electrochemical characteristics of a CMX (Neosepta, Tokuyama Corp.) Cation-Exchange Membrane. Relative hydrophobicity was controlled by the contact angle; XPS and SEM were used for characterizing chemical composition and microrelief of the surface, respectively. Voltammetry, chronopotentiometry, and mass transfer rate measurements were made as well. A “fresh” Membrane and samples after 10, 25, 100, and 150 h of operation in an electrodialysis cell at an overlimiting current equal to 3 theoretical limiting currents, in a 0.02 M NaCl solution, were characterized. Some electrochemical properties were also measured for a Neosepta Cation-Exchange Membrane, aged 2 years, in an industrial food process. It was found that the hydrophobicity of the CMX Membrane has increased after the first 10 h of operation; more and more cavities of the dimension of the order of 1 μm have appeared with time testifying electrochemical erosion of the surface. The limiting current densi...
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Bi-ionic potential through a Cation Exchange Membrane separating two electrolyte solutions at different concentrations
Electrochimica Acta, 2001Co-Authors: S. Tran, Lasâad Dammak, Christian Larchet, Bernard AuclairAbstract:Abstract We have studied the bi-ionic potential (BIP) through an ion-Exchange Membrane separating two electrolyte solutions having the same co-ion, different counter-ions and different concentrations. This study is carried out for a Cation Exchange Membrane (CM1: a polystyrene and divinylbenzene sulfonated Membrane), for three electrolyte pairs (ACl—BCl where A, B ∈ {K, Na, Li}) and for two stirring rates (ω 0 = 0 rpm and ω max = 900 rpm). Our experimental results show that the higher the concentration of the more mobile counter-ion (A) the higher the BIP, and conversely for B. The BIP variation versus the logarithm of the concentration of one solution is almost linear until 0.1 M for all the systems studied. The stirring rate, ω, has no influence on the BIP values if the concentration of A or B is very small (of the order of 0.001 M). However, if the concentrations of A and B are greater than 0.01 M, ω has a non-negligible effect which is attributed to the existence of diffusion boundary layers. The influences of the co-ion flux, of the solvent flux and of the counter-ion hydrated volumes have been examined.