Layer-by-layer (LbL) polyelectrolyte membrane with Nexar™ polymer as a polyanion for pervaporation dehydration of ethanol

Novel LbL polyelectrolyte multilayer membrane (PEMM) with Nexar™ polymer, a sulfonated pentablock copolymer, as the polyanion on a hydrolyzed polyacrylonitrile (PAN) hollow fiber substrate has been developed for pervaporation dehydration of ethanol. The advantages of applying the sulfonated copolymer as the polyanion are that the required bi-layer numbers can be significantly reduced while achieving a good separation performance. With just one bi-layer of polyethyleneimine (PEI) polycation and Nexar™ polyanion, the newly developed PEMM shows a flux of 1160 g/m² h and a separation factor of 127 at 50 °C for ethanol dehydration. The PEMM exhibits good stability up to a 170-h continuous operation with a flux decline at the initial stage because of substrate densification. This study demonstrates the possibility of employing the sulfonated pentablock copolymer as a polyanion for PEMMs to dehydrate biofuel via pervaporation.