Water,salt, and ethanol diffusion through membranes for water recovery by forward (direct) osmosis processes

Measurements of the diffusive permeances of water, NaCl, and ethanol through several, unoptimized membranes are presented. Such data can facilitate analysis and development of water recovery from highly impaired sources using hybrid processes based on forward (direct) osmosis (FO) with aqueous ethanol solutions as the “osmotic” agent. The membranes we have studied include anion and cation exchange materials and cross-linked poly(vinylalcohol) (PVA) gels, the latter being a membrane chemistry commercially used for ethanol dehydration via pervaporation. The measured transport properties are reported and suitability of these materials for an FO-based water recovery process is discussed in the context of process simulations.