Fabrication of mixed matrix membranes blending with the TiO₂/Bi₃O₄Cl 2D/2D heterojunction for photocatalytic degradation of tetracycline

The photocatalytic composite membranes had becoming potential functional material for wastewater treatment because of facile separation of solid liquid phases after-treatment process. In this study, the 2D/2D TiO2/Bi3O4Cl heterojunctions were designed as a functional photocatalyst to prepare a series of PVDF photocatalytic membranes through phase inversion method. This tight-contact 2D/2D heterostructure results in shorter migration distance of photo-generated carriers to the surface of the 2D/2D TiO2/Bi3O4Cl heterojunctions, so that it can faster participation in photocatalytic degradation. Moreover, the 2D/2D heterostructure can improve the pore structure of membrane, which will enhance the porosity and mean pore size, and then providing more photocatalytic active sites for degradation process. As a result, under optimal conditions, the TiO2/Bi3O4Cl/PVDF membranes exhibited a higher tetracycline (TC) degradation rate of 88.85% in comparison with pure PVDF membranes. The cyclic degradation experiment proved that the TiO2/Bi3O4Cl/PVDF membranes showed good stability after several cycles. This work highlights the construction of 2D/2D heterojunction and the improvement of the photocatalyst property by special membrane structure and their application in wastewater treatment.