Super hydrophilic composite membrane with photocatalytic degradation and self-cleaning ability based on LDH and g-C3N4

In this work, the layered double hydroxide @ graphitic nitrogen carbide (LDH@g-C3N4@PDA) composite photocatalysts were fabricated by dopamine modification method. Then, the LDH@g-C3N4@PDA and graphene oxide (GO) composites were assembled on PVDF membrane to construct the photocatalytic self-cleaning composite membrane. The prepared PVDF/LDH@g-C3N4@PDA/GO composite membrane has excellent performance in contaminant separation and photocatalytic degradation. The rejection rates of methylene blue (MB), rhodamine b (RhB), gasoline, diesel, and petroleum ether were 100%, 94.61%, 96.74%, 93.22%, and 92.35%, respectively. More importantly, under visible-light irradiation, the membrane could achieve continuous and simultaneous flow-through separation and degradation of dye in short time. The rejection rate and the flux of organic dye were 99.28% and 397.14 L.m(-2) h(-1) bar(-1). The photocatalytic cycle experiment, which has been repeated 10 times, have also revealed the stability and high efficiency of PVDF/LDH@g-C3N4@PDA/GO membrane on account of its superior photocatalytic self-cleaning function. Therefore, this self-cleaning composite membrane would have a range of applications in wastewater treatment.