Effect of the incorporation of graphene oxide filler on the performance of sodium alginate/polyvinyl alcohol draw agent hydrogel for forward osmosis desalination

Abstract Hydrogels are typically 3D networks of hydrophilic polymers, which can hold a specific amount of water. They have recently been utilized to draw freshwater in forward osmosis (FO) desalination processes. In this study, we looked at how adding different amounts of graphene oxide (GO) nanosheets to sodium alginate/polyvinyl alcohol (SA/PVA) hydrogel affects its ability to draw clean water in the FO desalination process. The formed SA/PVA/GO hydrogel was characterized by swelling measurements, scanning electron microscopy, compression strength testing, Fourier-transform infrared spectroscopy, and X-ray diffraction to determine the optimum GO content. Then, the optimized SA/PVA/GO hydrogel was applied as a draw agent in an FO batch cell that we used in our earlier studies. The results showed that the optimal GO/total cross-linked polymer blend mass ratio was 0.0025, which augmented the swelling ratio of the neat hydrogel from 1676 to 3610 after 1 h and from 5470 to 5689 after 24 h. Moreover, this ideal mass ratio increased the FO water flux from 0.335 L/m 2 .h to 0.646 L/m 2 .h in an hour.