Polymer-Grafted Graphene Oxide as a High-Performance Nanofiller for Modification of Forward Osmosis Membrane Substrates

Abstract

A substrate with good physicochemical properties is essential for minimizing unpleasant internal concentration polarization phenomena in a forward osmosis (FO) process. In this study, graphene oxide-graft-poly(2-hydroxy ethyl methacrylate) (GO-g-PHEMA, GP) nanoplates with different weight ratios were prepared for the first time using a combination of click chemistry and reversible addition–fragmentation chain-transfer polymerization. Then, high-efficiency thin-film nanocomposite (TFN) FO membranes were fabricated using GP-modified polysulfone (PSf) substrates. The influence of the structure parameter and concentration of GP on the substrate and polyamide (PA) active layer properties were systematically studied using various characterization methods. The obtained results indicated that the morphologies of the GP-modified PSf substrates were more porous, and the pure water flux, surface hydrophilicity, and mean pore size of the substrates considerably improved. Furthermore, the GP/PSf-based TFN membranes showed thicker, rougher, and permeable PA active layers than the baseline PSf-based TFC membrane. In the case of TFN-FO membranes, the water permeability noticeably increased, and the structural parameter effectively declined. Additionally, the FO performance dramatically improved (e.g., the water flux of TFN-GP210.4 reached 32.6/15.6 LMH under PRO/FO configuration). According to the results, it can be concluded that 0.4 wt % of GP21 nanofiller (GO/PHEMA ratio of 2:1) was the optimal blend concentration. Also, the modified membranes showed a noticeable performance in Caspian seawater desalination.