Separation of Organic Compounds from Surfactant Solutions by Pervaporation. The Influence of a Micellar Phase on Mass Transfer

Abstract

Abstract Volatile organic compounds (VOCs) can be separated from aqueous micellar surfactant solutions with high efficiency by pervaporation processes using organophilic polymer membranes. This seems to be a surprising result because the transmembrane flux of a VOC strongly depends on its volatility, which is rather low in the presence of a surfactant at concentrations far above the critical micellar concentration. Based on results of equilibrium measurements in micellar systems and pervaporation experiments, a theoretical analysis of the mass transfer is given. It is shown that the mass transfer for VOCs in the liquid boundary layer of a pervaporation membrane in the presence of a micellar phase cannot be described by molecular diffusion processes alone. Obviously, the mass transfer is enhanced considerably by diffusing micelles which transport the solubilized VOC molecules in direction to the surface of the membrane.