Fast-responsive monolithic hydrogels as draw agent for forward osmosis membrane process

A monolithic copolymer hydrogel was synthesised by polymerising n-isopropylacrylamide and sodium acrylate in the presence of poly(sodium 4-styrenesulfonate) (PSSS) chains and studied as potential draw agent for forward osmosis (FO) process. The monolithic hydrogel synthesised from 19% NIPAM, 1% SA, and 15% PSSS at 60°C generated higher FO water flux and higher recovery rate than other hydrogels, due to improved membrane-hydrogel contact and water transport. In particular, the synthesised hydrogel draw agent achieved twice water flux compared with the particles. The monolithic hydrogel containing a smaller amount of water produced a higher water flux due to its high swelling pressure.