A self-cleaning hierarchical carbon nitride-based membrane for highly efficient oily wastewater purification

Nowadays, membrane fouling critically limits the further application in high-efficient oily emulsions separation. Herein, we constructed a hierarchical visible-light driven self-cleaning membrane by metal-tannin complex synergistically manipulating self-assembly g-C3N4 nanosheets and followed in-situ mineralization of β-FeOOH on g-C3N4/TA membrane. The TA-metal complex manipulated the stability of g-C3N4-based membrane, and the uniform distribution of mineralized layer onto membranes endued g-C3N4/[email protected] with outstanding wettability. Herein, g-C3N4/[email protected] membranes exhibited highly oil/water emulsion separation efficiency (above 99.1%) with relatively high water permeance (639.9–1349.4 L m−2 h−1 bar−1), simultaneously possessed exceeding anti-fouling properties. In addition, the synergistic effect between photo-Fenton reaction of β-FeOOH and photocatalytic ability of g-C3N4 nanosheets improved the visible-light driven photodegradation performance of composite membranes, which could completely separate MB/oil mixture emulsions. Our work showed integration of membrane separation and photodegradation technology effectively separated oily contaminations from polluted water and alleviated the membrane fouling problems, further pushing forward to practical application of oil-water separation membranes.