Nanofiltration membrane with substrate incorporated amine-functionalized graphene oxide for enhanced petrochemical wastewater and shale gas produced water desalination

Polyamide (PA) nanofiltration (NF) membranes were fabricated via interfacial polymerization (IP) with graphene oxide (GO)/aminated GO (NGO)-incorporated substrate and then compared for petrochemical wastewater and shale gas produced water desalination. Crosslinking degree of PA layer with GO-incorporated substrate and NGO-incorporated substrate was higher than pristine membrane. Water flux of TFCGO-0.05 (with GO addition mass of 0.05 wt%) and TFCNGO-0.075 (with NGO addition mass of 0.075 wt%) membrane substantially increased by 15.6% and 26.9% with the highest flux of 44.93 and 49.30 L m-2 h-1, respectively, while slight difference was observed for Na2SO4, MgSO4, NaCl rejection. The better performance of TFCNGO than TFCGO was attributed to much thinner PA layer due to relatively larger pore size, higher hydrophilicity, and possible reaction of amino group of NGOs with TMC, which resulted in lower PA layer thickness of TFCNGO membranes. Substantial enhancement of water flux (higher than 24.8%) and similar divalent ion rejections can be observed for petrochemical wastewater, as consistent with the single salt test. However, better performance in permeability and divalent ion rejections (approximately 6% higher than pristine membrane) was observed for shale gas produced water. These results also demonstrated that it is feasible to incorporate NGO into substrate for NF fabrication to improve performance for industrial water desalination.