Fouling resistant, high flux, charge tunable hybrid ultrafiltration membranes using polymer chains grafted graphene oxide for NOM removal

The unprecedented performance of fouling resistant, high flux and high rejection hybrid ultrafiltration polysulfone membranes with charge tunable channels using functionalized polymer chains grafted graphene oxide (SPK-g-GO) nanosheets for natural organic matter removal from aqueous feed is herein reported. The novel SPK-g-GO nanosheets were first prepared by esterification reaction at 55 °C using hydroxylated sulfonated poly(ether ether ketone) and graphene oxide. Then, polysulfone blend hybrid membranes with charge tunable channels were produced via the non-solvent induced phase separation method and optimized by varying the SPK-g-GO concentration from 1 to 8 wt.% in the casting solution. The membranes were characterized using scanning electron microscopy, Raman spectroscopy, atomic force microscopy, surface zeta potential and contact angle measurements. The surface texture and hydrophilicity of the membranes were altered due to the incorporation of SPK-g-GO. The hybrid membrane’s water flux was highly dependent on the amount of SPK-g-GO incorporated within the membrane matrix. The maximum water flux (485.7 L m−2 h−1), obtained using the membrane with 4 wt.% SPK-g-GO, was almost 270% higher than that of the membrane without SPK-g-GO (181.1 L m−2 h−1). The fouling resistance and natural organic matter retention capabilities of the membranes were examined via UF tests of synthetic natural organic matter solution at 1 bar feed pressure and neutral pH. The hybrid membrane with 4 wt.% SPK-g-GO loading exhibited remarkable improvement over the pristine one, rejecting more than 86% of the and recovering ~90% of its initial water flux after washing with a stable retention rate during a long-term filtration test.