Enhancing the permeability, anti-biofouling performance and long-term stability of TFC nanofiltration membrane by imidazole-modified carboxylated graphene oxide/polyethersulfone substrate

In this study, we attempt to enhance the permeability, biofouling resistance, and long-term stability of thin-film composite (TFC) nanofiltration membrane by tailoring the substrate membrane. Firstly, an imidazole-modified carboxylated graphene oxide (Im-CGO) with improved antibacterial property was synthesized. Next, the imidazole-modified carboxylated graphene oxide/polyethersulfone (Im-CGO/PES) ultrafiltration membrane was fabricated, and the corresponding TFC nanofiltration membrane was obtained based on the Im-CGO/PES substrate by interfacial polymerization. The pore structures, surface hydrophilicity, and permeability of Im-CGO/PES substrate membrane are improved by the introduction of membrane modifier (Im-CGO). Significantly, the water permeability of Im-CGO/PES based TFC membrane is greatly enhanced. The pure water flux of NF-0.5 membrane is 69.8 L m-2 h-1 at 0.6 MPa, and which is 80.8% higher than that of NF-0 membrane. The corresponding anti-biofouling test results suggest that Im-CGO/PES based TFC membrane possesses good anti-biofouling performance owing to the great increased surface hydrophilicity and a large number of antibacterial imidazole groups in substrate membrane. Furthermore, the long-term stability of Im-CGO/PES based TFC membrane is also enhanced compared to the PES based TFC membrane, attributing to the covalent connection between polyamide layer and Im-CGO/PES substrate.