Preparation of g-C3N4/TiO2/BiVO4 composite and its application in photocatalytic degradation of pollutant from TATB production under visible light irradiation

A novel and highly efficient ternary mpg-C3N4/BiVO4/TiO2 composite was successfully synthesized and characterized with regard to structure, chemical composition, optical properties and degradation application. The photocatalytic activities of as-prepared samples were evaluated by the photocatalytic decomposition of methylene blue (MB), practical effluent from alkylation and amination steps in 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) production. Compared with TiO2, BiVO4, and mpg-C3N4, the binary composites TiO2/BiVO4 and the ternary mpg-C3N4/BiVO4/TiO2 composites exhibited the higher photocatalytic activity under visible light irradiation. Compared to solo mpg-C3N4 and BiVO4, the photocatalytic efficiency of g-C3N4/TiO2/BiVO4 raised up to 94%. The catalytic activity of g-C3N4/TiO2/BiVO4 against TATB (alkylation and amination) also confirms its efficiency by creating intermediate which were detected by Q-TOF-MS. The thermal stability and photo-stability of the produced composites were investigated. From the view of practical application, mpg-C3N4/BiVO4/TiO2 displayed superior photostability after five times recycle. The mechanism research showed the fitting of band structure among BiVO4, g-C3N4, and TiO2. The presence of mpg-C3N4 and BiVO4 can notably adjust the band gap energy and the synergy effects of them can prolong the lifetime of the charge carrier. (C) 2018 Elsevier B.V. All rights reserved.