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Abstract The present work examines, for the first time, the use of thiolated graphene oxide (TGO), in polyelectrolyte composite membranes as an effective approach to enhance the MFC performance. A new composite membrane based on a... more
Abstract The present work examines, for the first time, the use of thiolated graphene oxide (TGO), in polyelectrolyte composite membranes as an effective approach to enhance the MFC performance. A new composite membrane based on a sulfonated polyethersulfone (SPES) hybrid with GO, sulfonated GO (SGO), and TGO was fabricated and assessed in MFC. The blend membranes were characterized with various techniques. The sulfhydryl (-SH) and sulfonic (-SO3H) groups enhanced the proton selectivity of the membrane and MFC performance. The MFC using the SPES/SGO1.8% composite membrane generated a power density of 66.4 mW/m2 which was double that produced by MFC using Nafion117 membrane in batch mode which lasted for 8 days. The SPES/SGO membrane was more selective towards H+ rather than other cations (K+, Na+, and Li+). This was also confirmed by the results of proton conductivity analysis, as the SPES/SGO1.8% membranes showed a value of 1.42 mS/cm which was higher than Nafion117 (1.3 mS/cm), SPES/TGO1.8% (1.25 mS/cm), SPES/GO1.8% (0.56 mS/cm), and SPES (0.32 mS/cm). The higher COD removal and coulombic efficiency were obtained in MFC with SPES/SGO membranes. In conclusion, it is our view that the new SPES/SGO and SPES/TGO membranes can be applied favorably in dual-chamber MFCs meeting their needs.
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A simple and accurate determination of the point of zero charge of a ceramic membrane is reported. It is based on pH variation measurements on adding an amphoteric oxide in a solution of a given pH. Up to now this method was effective for... more
A simple and accurate determination of the point of zero charge of a ceramic membrane is reported. It is based on pH variation measurements on adding an amphoteric oxide in a solution of a given pH. Up to now this method was effective for studying powder dispersions. In this work it is extended to ceramic membranes. In fact, we present
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L'etude des proprietes electriques et electrocinetiques d'une membrane constitue une etape essentielle pour la comprehension et la maitrise de sa selectivite. En effet, les performances de filtration d'une membrane ne sont en... more
L'etude des proprietes electriques et electrocinetiques d'une membrane constitue une etape essentielle pour la comprehension et la maitrise de sa selectivite. En effet, les performances de filtration d'une membrane ne sont en general pas regies par les seules caracteristiques geometriques du materiau membranaire mais sont egalement affectees par les interactions electrostatiques entre les especes en solution et la surface de la membrane. Cette these traite de la caracterisation des proprietes electriques et electrocinetiques de membranes ceramiques de micro- et d'ultrafiltration. Dans cet objectif, quatre methodes experimentales (potentiel d'ecoulement, electro-osmose, potentiel de membrane et mesure de la resistance electrique de membrane par la technique d'impedance electrochimique) sont mises en uvre. Afin de relier les diverses grandeurs accessibles experimentalement au potentiel zeta ou au potentiel au plan d'helmholtz externe, grandeurs caracteristiques de l'interface membrane-solution, un modele de charge d'espace incluant une resolution numerique de l'equation non-lineaire de poisson-boltzmann est developpe. Celui-ci decrit le transport d'un electrolyte symetrique (en considerant les diffusivites individuelles des cations et des anions), a l'interieur d'un pore cylindrique homogene. Outre la determination du potentiel zeta ou du potentiel au plan d'helmholtz externe, ce modele permet l'analyse, et donc une meilleure comprehension, des phenomenes electriques et electrocinetiques se produisant a l'interieur des pores d'une membrane. La fiabilite du modele est verifiee en terme de conductivite electrolytique a l'interieur des pores d'une membrane ceramique d'ultrafiltration en confrontant les valeurs theoriques aux valeurs experimentales deduites de mesures de resistance electrique de membrane.
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This article discusses macroscopic modeling of the transport mechanisms of ions through nanofiltration membranes. The modeling is based on mechanistic approaches that consider nanofiltration membranes as bundles of (nano)pores and ionic... more
This article discusses macroscopic modeling of the transport mechanisms of ions through nanofiltration membranes. The modeling is based on mechanistic approaches that consider nanofiltration membranes as bundles of (nano)pores and ionic transport as resulting from hindered diffusion, electromigration, and convection. The governing equations are presented and the main assumptions and approximations are reviewed and discussed. Special attention is given to the uniform potential approximation (also called homogeneous approximation), which forms the basis of most current transport models used in nanofiltration. The impact of steric hindrance, membrane fixed charge density, and salt concentration on the rejection of single-salt solutions and electrolyte mixtures is illustrated through a series of examples. Some recent advances in nanofiltration modeling (introduction into transport models of the dielectric exclusion phenomena and spatial inhomogeneities of the fixed charge) are also briefly discussed. Keywords: nanofiltration; transport phenomena; modeling; charged membranes; transport theory
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Research Interests: Chemistry, Electrochemistry, Kinetics, Polymers, Medicine, and 13 moreMultidisciplinary, Environmental science and technology, Nanofiltration, Electrokinetic Phenomena, Membrane, Sodium Hypochlorite, Fourier transform infrared spectroscopy, Time Factors, Polyvinylpyrrolidone, Hydrogen-Ion Concentration, Hypochlorite, Oxidation-Reduction, and Static Electricity
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... Anthony Szymczyk Corresponding Author Contact Information , E-mail The Corresponding Author and Patrick Fievet. ... the distribution of ions at the pore inlet and outlet [2], [3], [4], [5], [6], [7] and [8]. Among these continuous... more
... Anthony Szymczyk Corresponding Author Contact Information , E-mail The Corresponding Author and Patrick Fievet. ... the distribution of ions at the pore inlet and outlet [2], [3], [4], [5], [6], [7] and [8]. Among these continuous models, the so-called DSPM (Donnan-Steric partitioning ...
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ABSTRACT Although the electrokinetic characterisation of particle deposits during filtration is of a great importance for better understanding of the mechanisms involved in the deposit build-up, few studies have been devoted to this... more
ABSTRACT Although the electrokinetic characterisation of particle deposits during filtration is of a great importance for better understanding of the mechanisms involved in the deposit build-up, few studies have been devoted to this characterisation so far. The present study focuses on the description and validation of a method for in situ and real time electrokinetic characterisation of cakes. This method is based upon simultaneous measurements of transversal streaming potential and permeate flux before and during the cake formation. The measurements of the streaming potential at a constant pressure have been preferred to those obtained by pressure steps in order not to modify the cake structure. Indeed, a densification of the cake structure with pressure steps might lead to pressure-dependent streaming potential coefficients. Mono-disperse suspensions of (negatively charged) polystyrene latex and (positively charged) melamine at various particle concentrations were filtered in a dead-end mode through a negative polyethersulfone membrane. It was found that the global streaming potential coefficient increased in absolute value with the deposited latex quantity, whereas it decreased and changed of sign during the filtration of melamine suspensions. The streaming potential coefficient of the deposit was deduced from the electrokinetic and hydraulic measurements performed through the membrane and “membrane+deposit”. The method was validated by (i) the right charge sign obtained for latex and melamine deposits, (ii) the independence of the streaming potential coefficient of deposits on both deposit thickness and growth kinetics. The main advantage of the method is its ability to evaluate the streaming potential coefficient of the single deposit without disturbing its build-up. Nevertheless, it is limited to the characterisation of sufficiently resistive deposits.
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Abstract Over the last decades only a few atomistic simulations were performed to investigate water transport through polyamide reverse osmosis membranes at the molecular scale. In most reported simulations water uptake by the membrane... more
Abstract Over the last decades only a few atomistic simulations were performed to investigate water transport through polyamide reverse osmosis membranes at the molecular scale. In most reported simulations water uptake by the membrane was fixed on the basis of scarce experimental data available in the literature but it has never been predicted directly from explicit molecular simulations of water transport across the membrane/water interface. This was attempted in the present work by using a technique based on non-equilibrium molecular dynamics simulations. The prediction of the membrane water uptake is indeed of the utmost importance for (i) validating an atomistic model of a polymer membrane and (ii) getting an accurate picture of the molecular mechanisms ruling water transport through the membrane. Simulations performed in the present work led to a water content inside a cross-linked fully aromatic polyamide membrane around 24 wt% in very good agreement with reported experiments. We further showed that this high water uptake results from favorable interactions between the polyamide membrane and water molecules, which compensates the decrease in the number of hydrogen bonds between water molecules inside the membrane. Eventually, it was shown that water molecules confined in the membrane formed an interconnected hydrogen-bond network made of cyclic and linear aggregates.
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For charged porous membranes, the separation efficiency to charged particles and ions is affected by the electrical properties of the membrane surface. Such properties are most commonly quantified in terms of zeta-potential. In this... more
For charged porous membranes, the separation efficiency to charged particles and ions is affected by the electrical properties of the membrane surface. Such properties are most commonly quantified in terms of zeta-potential. In this paper, it is shown that the zeta-potential can be calculated numerically from the membrane potential. The membrane potential expression for charged capillary membranes in contact with
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In this study, we test the validity of the space charge model in the case of a ceramic microporous membrane. To this end, experimental measurements of the electrical resistance in pores are performed with the membrane filled with KCl... more
In this study, we test the validity of the space charge model in the case of a ceramic microporous membrane. To this end, experimental measurements of the electrical resistance in pores are performed with the membrane filled with KCl solutions of various concentrations. The electrolyte conductivity within the membrane pores is deduced from these experiments. In situations where the contribution
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Two electrokinetic techniques, electro-osmosis and streaming potential, have been used to investigate the charge characteristics of mixed alumina/titania/silica microfiltration membranes. Both methods can be applied to the membrane itself... more
Two electrokinetic techniques, electro-osmosis and streaming potential, have been used to investigate the charge characteristics of mixed alumina/titania/silica microfiltration membranes. Both methods can be applied to the membrane itself and streaming potential can be measured during the filtration process. Electroosmosis and streaming potential give very close results in term of isoelectric points, whatever the electrolyte is. The low isoelectric point
Research Interests: Engineering, Chemistry, Desalination, Silica, Microfiltration, and 14 moreElectrokinetic Phenomena, Electro-Osmosis, Membrane, CHEMICAL SCIENCES, Ceramic Membrane, Surface Properties, Surface Charge, Streaming Potential, Ionic Strength, Zeta Potential, Electrolyte, Streaming current, Isoelectric point, and electroosmotic flow
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