Cross-Linked and Doped Graphene Oxide Membranes with Excellent Antifouling Capacity for Rejection of Antibiotics and Salts

Graphene oxide (GO) membranes have suffered from the instability of water permeability and low rejection of pollutant separation. In this paper, a reasonable modification protocol for GO nanosheets at the molecular level was proposed. A molecular cross-linking strategy was adopted to regulate the interlayer spacing of GO nanosheets, and nanofiltration membranes with high water stability and excellent antifouling capacity were prepared, which could effectively reject antibiotics and salts. The GO1-MPD0.5 (the mass ratio of GO nanosheets to MPD is 1:0.5) and GO/GO1-MPD0.5-0.25 (the doping ratio of GO1-MPD0.5 is 25%) membranes had stable water permeability of 4.22 ± 0.06 and 3.65 ± 0.11 L m-2 h-1 bar-1, and the rejection rates for ciprofloxacin (CIP) and ofloxacin (OFX) were 93.35 ± 3.62 and 95.48 ± 2.97 and 85.89 ± 6.52 and 88.21 ± 3.67%, respectively. Molecular dynamics simulations well explained the high water stability of membranes, and the cross-linked hydrophobic benzene ring played a role in the rejection of pollutant molecules. Moreover, the GO1-MPD0.5 membrane showed excellent antifouling capacity and the flux recovery ratio (FRR) was more than 98%. This paper provides a new idea for the design of nanofiltration membranes with high stability and good rejection permeability at the molecular level and provides a prospect for the application of nanofiltration membranes in practical water treatment and water purification.