Sustainable Osmotic-Driven Clean Water Recovery through Thermoresponsive Polymer Hydrogels with a Selective Polyamide Coating

This study introduces a water treatment system utilizing a poly(N-isopropylacrylamide) PNIPAM hydrogel as a support material, coated with a polyamide (PA) selective layer, for water treatment and sample concentration applications. The thermoresponsive nature of the PNIPAM hydrogel enables efficient water recovery through heat-induced deswelling, with a consistent performance observed over multiple swelling/deswelling cycles. The resistance of the PA coating to multiple cycles of swelling and deswelling is explored, revealing that the PA films composed of 0.4 wt % trimesoyl chloride (TMC) retained their rejection performance even after repeated heat-induced deswelling, an essential feature for long-term usability. The selectivity of the optimized PA/1-0.4 sample (composed of 1 wt % MPD and 0.4 wt % TMC) is evaluated against various aqueous salts, demonstrating the effective rejection of both divalent and monovalent ions. This development enhances the sustainability of water treatment and sample concentration processes, holding great promise for a range of environmental and analytical applications.