Liquid transport through sulfonated cation-exchange membranes for different water-alcohol solutions

Abstract

The aim of this work was to study the sorption and transport of different water–alcohol solutions (methanol, ethanol, 1-propanol and 2-propanol solutions) when a Nafion 117 membrane is separating them. It was observed that methanol permeability remains constant when varying the composition of the mixture. However, the permeability for the other alcohol solutions decreases from alcohol concentrations that are different for each alcohol. In addition, it was aimed to compare the behavior of membraneswith different morphologies when they were separating water and water–alcohol solutions. Nafion 117membrane and two sulfonated cation-exchange membranes (CR65-AZL-412 and MK-40) were used. Measurements of sorption and liquid transport were made using methanol and ethanol solutions. The uptake values for Nafion 117 membrane were higher than those obtained for CR65-AZL-412 and MK-40 membranes. The results reveal that, in contrast to Nafion membrane, a non-negligible water flux through CR65-AZL-412 and MK-40 membranes was observed along with the alcohol diffusion through them. For these two latter membranes the permeability could not be calculated since the alcohol diffusion is not the only physical process that should be considered. In spite of it, the alcohol and water fluxes through CR65-AZL-412 and MK-40 were estimated; turning out that the water flux was higher than alcohol flux.