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© 2003 Elsevier Inc. This work was supported by the Ministry of Science and Technology of Spain, Project BFM2000-0625., The volume flux through a cation-exchange membrane (Nafion 117) separating two equal electrolyte water-methanol solutions as a function of the pressure difference was determined under different experimental conditions. The results show that permeation rates through the membrane are strongly dependent on the methanol content of the solutions, thus the value of the flux increases when the methanol percentage increases. The effect of the electrolyte concentration of the solution on the membrane permeability is less important, although its influence becomes significant at low electrolyte concentration and high methanol content on solvent. This behavior is explained in terms of the amount of solvent sorbed by the membrane. Typical flux behaviors observed with pressure difference are linear at low pressures, exhibiting a positive deviation at higher pressure difference values., Ministry of Science and Technology of Spain, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Elsevier Science (USA). Financial support from Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged., In this paper, an experimental study was carried out in order to investigate the osmotic transport of methanol-water electrolyte solutions through a Nation membrane. The experimental data indicated that the Nafion membrane showed the typical anomalous osmotic behavior of charged membranes. The influence of some relevant parameters, such as electrolyte concentration difference, weight fraction of methanol on solution, and nature of cation was considered. The results showed that the osmotic volume flow was decreased with the presence of methanol on solvent, but did not alter the anomalous osmotic behavior of the membrane., Ministerio de Ciencia y Tecnología, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2005 Elsevier. Financial support from Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged, The volume flow of methanol-water potassium chloride solutions through a Nation membrane originated by the simultaneous action of electric potential and pressure gradients has been measured at different percentage, of methanol. Measurement were conducted when both gradients act in the same and in the opposite directions under different experimental conditions. The result, indicate that the simultaneous action of the pressure and potential differences originates a total flow different from the sum of the individual electroosmotic and permeation flows due to each force acting separately. The application of the irreversible thermodynamics theory, which includes second-order terms, allowed the study of the influence of the composition of the solutions on the determination of the different phenomenological coefficients., Ministerio de Ciencia y Tecnología of Spain, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 Elsevier Inc. The authors of this study gratefully acknowledge Prof. C. Larchet and Prof. V. Nikonenko for donating MK40 membrane samples. Financial support from Universidad Complutense de Madrid under Project PR1/08-15918-A is also gratefully acknowledged., Solvent uptake, hydraulic and electroosmotic permeabilities, true cation transport number, effective fixed charge concentration, and limiting current values have been determined in aqueous LiCl solutions for three commercial cation-exchange membranes with different morphologies and similar electric properties. The differences found in the equilibrium and transport properties of the membranes have been analyzed on the basis of their different structures. The experimental results show that the membrane morphology has an influence on the effect that the presence of an electrolyte has in the solvent uptake and in the liquid permeation. Differences have also been found in the polarization concentration effects, and on the loss of the membrane selectivity with the increase of the electrolyte concentration., Universiclad Complutense de Madrid, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 Elsevier. Financial support from the Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged., The volume flow through a Nafion membrane originated by the simultaneous action of an electric potential difference and a pressure difference has been measured using aqueous KCl solutions under different experimental conditions. The behavior has been analyzed when both gradients act in the same and in the opposite sense. The results indicate that the simultaneous action of the pressure and potential differences originates a total flow different from the sum of the electroosmotic and permeation flows due to each force acting separately. The application of irreversible thermodynamics, which includes second-order terms, allowed the determination of the phenomenological coefficients. Moreover, from these values, the equivalent pore radius was estimated on the assumption that the membrane is a porous medium filled with an internal solution., Ministerio de Ciencia y Tecnología, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 Elsevier Inc. The authors of this study gratefully acknowledge Prof. C. Larchet and Prof. V. Nikonenko for donating MK40 membrane samples. Financial support from Universidad Complutense de Madrid under Project PR1/08-15918-A is also gratefully acknowledged., Solvent uptake, hydraulic and electroosmotic permeabilities, true cation transport number, effective fixed charge concentration, and limiting current values have been determined in aqueous LiCl solutions for three commercial cation-exchange membranes with different morphologies and similar electric properties. The differences found in the equilibrium and transport properties of the membranes have been analyzed on the basis of their different structures. The experimental results show that the membrane morphology has an influence on the effect that the presence of an electrolyte has in the solvent uptake and in the liquid permeation. Differences have also been found in the polarization concentration effects, and on the loss of the membrane selectivity with the increase of the electrolyte concentration., Universiclad Complutense de Madrid, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2005 Elsevier. Financial support from Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged, The volume flow of methanol-water potassium chloride solutions through a Nation membrane originated by the simultaneous action of electric potential and pressure gradients has been measured at different percentage, of methanol. Measurement were conducted when both gradients act in the same and in the opposite directions under different experimental conditions. The result, indicate that the simultaneous action of the pressure and potential differences originates a total flow different from the sum of the individual electroosmotic and permeation flows due to each force acting separately. The application of the irreversible thermodynamics theory, which includes second-order terms, allowed the study of the influence of the composition of the solutions on the determination of the different phenomenological coefficients., Ministerio de Ciencia y Tecnología of Spain, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 Elsevier. Financial support from the Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged., The volume flow through a Nafion membrane originated by the simultaneous action of an electric potential difference and a pressure difference has been measured using aqueous KCl solutions under different experimental conditions. The behavior has been analyzed when both gradients act in the same and in the opposite sense. The results indicate that the simultaneous action of the pressure and potential differences originates a total flow different from the sum of the electroosmotic and permeation flows due to each force acting separately. The application of irreversible thermodynamics, which includes second-order terms, allowed the determination of the phenomenological coefficients. Moreover, from these values, the equivalent pore radius was estimated on the assumption that the membrane is a porous medium filled with an internal solution., Ministerio de Ciencia y Tecnología, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Elsevier Inc. This work was supported by the Ministry of Science and Technology of Spain, Project BFM2000-0625., The volume flux through a cation-exchange membrane (Nafion 117) separating two equal electrolyte water-methanol solutions as a function of the pressure difference was determined under different experimental conditions. The results show that permeation rates through the membrane are strongly dependent on the methanol content of the solutions, thus the value of the flux increases when the methanol percentage increases. The effect of the electrolyte concentration of the solution on the membrane permeability is less important, although its influence becomes significant at low electrolyte concentration and high methanol content on solvent. This behavior is explained in terms of the amount of solvent sorbed by the membrane. Typical flux behaviors observed with pressure difference are linear at low pressures, exhibiting a positive deviation at higher pressure difference values., Ministry of Science and Technology of Spain, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Elsevier Science (USA). Financial support from Ministerio de Ciencia y Tecnología of Spain under Project BFM2000-0625 is gratefully acknowledged., In this paper, an experimental study was carried out in order to investigate the osmotic transport of methanol-water electrolyte solutions through a Nation membrane. The experimental data indicated that the Nafion membrane showed the typical anomalous osmotic behavior of charged membranes. The influence of some relevant parameters, such as electrolyte concentration difference, weight fraction of methanol on solution, and nature of cation was considered. The results showed that the osmotic volume flow was decreased with the presence of methanol on solvent, but did not alter the anomalous osmotic behavior of the membrane., Ministerio de Ciencia y Tecnología, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub