Interfacial polymerization nanofiltration membrane with visible light photocatalytic self-cleaning performance by incorporation of CQD/TiO2

Abstract Integration photocatalysis with membrane technology offers a potential solution to combat fouling dilemma. Herein, an interfacial polymerization polyamide nanofiltration (NF) membrane with self-cleaning ability was prepared by incorporation of carbon quantum dots /titanium dioxide (CQD/TiO2) nanoparticles (NPs). The addition of hydrophilic CQD/TiO2 NPs promoted membrane hydrophilicity and endowed the NF membrane with high water flux (67.22 L m−2h−1), which was 1.8 times compared with that of the pristine membrane, and salt rejection of Na2SO4 (96.7%). Simultaneously, the prepared NF membranes maintained high dye rejection to methyl blue (MYB, 99.1%) and congo red (99.8%). Moreover, visible light-driven photocatalytic ability of CQD/TiO2 allowed the membranes to efficiently degrade MYB dyes absorbed on the membrane surface. In stark contrast to the results of cyclic physical water cleaning, the flux recovery ratios were maintained 97–98% without sacrificing MYB rejections during the cyclic fouling-irradiation process, demonstrating stable and efficient self-cleaning performance. Even after continuous membrane fouling for 72 h, the water flux only decreased by 6.7% after visible light irradiation, surpassing the performance of pristine polyamide NF membrane (decreased by 23.4%). The hydrophilicity and visible light-driven self-cleaning ability make the prepared NF membrane via interfacial polymerization highly suitable for efficient dye wastewater treatment.