Zwitterion functionalized graphene oxide thin film nanocomposite membrane for brackish water desalination and natural organic matter removal

Thin-film composite (TFC) membranes incorporating nanocomposites has potential in water desalination and treatment. Herein, zwitterion-functionalised graphene oxide was incorporated into polyamide (PA) layer developed on polyethersulfone (PES) support through interfacial polymerization. The properties and performance of pristine TFC, TFC incorporating graphene oxide (GO) (TFC-GO), and zwitterion-grafted GO (TFC-ZGO) membranes were compared. These revealed that TFC-ZGO presented a relatively smoother surface and higher hydrophilicity compared to TFC and TFC-GO membranes analysed using AFM and water contact angle. All membranes were assessed using brackish water. The pristine TFC membrane presented lower pure water flux (39.04 L.m −2 .h −1 ), brackish water flux (15.23 L.m −2 .h −1 ) and salt rejection (NaCl: 30.2 % and MgSO 4 : 49.5 %) relative to membranes containing GO (58.09 L.m −2 .h −1 , 26.95 L.m −2 .h −1 and NaCl: 45.6 %) and ZGO (69.84 (TFC-ZGO 0.7 ) and 86.66 L.m −2 .h −1 (TFC-ZGO 0.9 )), BWF of 48.57 (TFC-ZGO 0.7 ), and 58.09 L.m −2 .h −1 (TFC-ZGO 0.9 ) and salt rejection (TFC-GO 0.7 (NaCl: 54.4 %, MgSO 4 : 86.4 %; TFC-ZGO 0.9 (NaCl: 57.4 % and MgSO 4 : 90.3 %). Furthermore, TFC-ZGO membranes exhibited superior antifouling properties (flux recovery ratio ( FRR) ranged between 89 % and 96 %) compared to pristine TFC membrane ( FRR = 67–76 %) and TFC-GO membranes ( FRR = 79–85 %). The excellent resistance to fouling properties exhibited by TFC-ZGO membranes stem from the presence of the zwitterion brushes in the PA layer, which reduced adsorption of foulants. • TFC membranes containing AEPPS@GO exhibited improved flux and fouling resistance. • The TFC-ZGO membranes exhibited higher salt rejection in real brackish water treatment. • Excellent reusability in actual brackish water were observed. • Membranes with high AEPPS@GO content exhibited better removal of NaCl and MgSO 4 salts, and NOM.