Development of a novel high flux and fouling-resistant thin film composite nanofiltration membrane by embedding reduced graphene oxide/TiO2

•rGO/TiO2 nanocomposite was synthesized as a hydrophilic modifier.•rGO/TiO2 was introduced to the interfacial polymerization of TFC–NF membrane.•The separation performance of the modified NF membranes was improved.•The fouling resistance of the modified NF membranes was improved.

A thin film nanocomposite nanofiltration (TFN–NF) membrane was prepared by interfacial polymerization between piperazine and trimesoyl chloride monomers and partially reduced graphene oxide (rGO)/TiO2 nanocomposite as a hydrophilic modifier. The surface properties of the prepared NF membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle measurements. These analyses confirmed the improved hydrophilicity and the smoother surface of the modified membranes. Furthermore, the separation performance of the membranes was evaluated using 2000 mg/L of Na2SO4 and NaCl solutions tested by cross-flow filtration system. TFN membrane containing 0.005 wt.% rGO/TiO2 presented the optimum separation performance, including 60.6 L/m2 h water flux and 93.57% and 36.61% salt rejection of Na2SO4 and NaCl solutions, respectively. The fouling resistance of the membranes was also studied using bovine serum albumin (BSA) protein as a model fouling agent, based on the water flux decline during the filtration process. Results showed that decoration of TiO2 nanoparticles onto GO nanosheets had dual effects on the TiO2 incorporation into the cross-linked active layer of NF membrane, thereby improved the fouling resistance of these membranes.