Novel graphene quantum dots (GQDs)-incorporated thin film composite (TFC) membranes for forward osmosis (FO) desalination

Abstract

Abstract This paper reports a novel class of thin film composite (TFC) membranes for forward osmosis (FO) desalination. The TFC membranes were fabricated via interfacial polymerization (IP) of aqueous mixture of polyethyleneimine (PEI) and graphene quantum dots (GQDs) with organic solution of trimesoyl chloride (TMC) on modified polyacrylonitrile (PAN) ultrafiltration substrates. The chemical structures and morphologies of the synthesized GQDs and the GQDs-incorporated membranes were studied by various characterization techniques. The synthesized GQDs exhibited a narrow size distribution of 1.0–4.0\u202fnm with an average size of 2.19\u202fnm, and the thickness were one to three graphene layers. The results showed that GQDs nanoparticles were covalently bonded to the polyamide chains. The optimized TFC membrane with 0.050\u202fwt% GQDs loading exhibited quite hydrophilic and neutrally charged membrane surface, along with an enhanced water flux of 12.9\u202fL\u202fm−2\u202fh−1 and a comparable reverse salt flux of 1.41\u202fg\u202fm−2\u202fh−1 when DI water and 0.5\u202fM\u202fMgCl2 were used as the feed solution and the draw solution, respectively. Also, the optimized GQDs-incorporated TFC membrane presented an especially good anti-fouling performance. Thus, incorporating the novel graphene nanomaterial into polymer membranes may present its great potential application in desalination, purification and wastewater treatment.