Catalysis Today, Vol.335, 527-537, 2019
Novel g-C3N4/TiO2/PAA/PTFE ultrafiltration membrane enabling enhanced antifouling and exceptional visible-light photocatalytic self-cleaning
Membrane fouling due to superhydropobicity of polytetrafluoroethylene ultrafiltration membranes (PTFE UFMs) represents a grand challenge for their practical applications in diverse water treatment industries. Surface immobilisation of hydrophilic and chemically stable inorganic metal oxides (TiO2, ZrO2, etc) has been developed to improve hydrophilicity of the PTFE UFMs, though they still suffer from expensive and repeating regenerations once fouled. To address such issues, we strive to firmly immobilize g-C3N4 modified TiO2 (g-C3N4/TiO2, hereafter CNTO) onto PTFE UFM via a facile plasma-enhanced surface graft technique using polyacrylic acid (PAA) as a bridging agent. As reported here, the obtained CNTO/PAA/PTFE UFM shows much smaller surface water contact angle (WCA) of 62.3 degrees than that of bare PTFE UFM(115.8 degrees), leading to enhanced water flux of 830 L m(-2) h(-1) in the initial ultrafiltration of modelled waste-water containing methylene blue (MB). The CNTO/PAA/PTFE UFM is highly resistant to fouling in the prolonged filtration of 1000 mg/L bovine serum albumin (BSA) solution, while the fouled CNTO/PAA/PTFE UFM is able to regenerate rapidly under either UV or visible-light irradiation. The enhanced performance of the novel CNTO/PAA/PTFE UFM is reasonably attributed to its high wettability and robust photocatalytic activity of the g-C3N4/TiO2 coating that follows different self-cleaning mechanisms under UV and visible light irradiations.