(90d) Highly Permeable Dual Selective Thin Film Composite Membranes for Forward Osmosis with Viscous Draw Solutes

Recently, a wide range of large draw solutes have been successfully developed and employed in the forward osmosis (FO) process with the advantages of high water flux, minimum reverse flux and easy recovery. However, the high viscosity of these large draw solutes tends to suffer from more severe internal concentration polarization (ICP) effects and internal fouling of the draw solutes in the membrane sublayers. To solve this problem, a dual selective flat sheet membrane has been designed in this study in order to prevent the viscous draw solutes from entering the porous support layer and minimize the ICP effects. Dense and thin polyamide layers have been fabricated on both the top and bottom surfaces of highly porous cellulose ester support through interfacial polymerization (IP). The dual selective thin film composite (TFC) membrane demonstrated reasonably high water flux and low salt reverse flux using sodium chloride as draw solutions at the concentrations ranging from 0.25M to 1M. When tested with viscous draw solutes including sucrose, ferric citric acid complex (Fe-CA) and polyethylene glycol monolaurate (PEG 640ML), significantly mitigated ICP effects and reduced fouling propensity were observed compared to single selective TFC membranes. This study proves the great potential for the combined use of the newly developed dual selective membrane with viscous draw solutes for various FO applications.