Synthesis of the composite catalyst Bi₄O₅Br₂/BiOBr for the improved photocatalytic degradation of oilfield produced wastewater

Composite photocatalysts have been shown to have improved photocatalytic performance, as such the composite, Bi₄O₅Br₂/BiOBr was synthesized by controlling the mole ratio of Bi(NO₃)₃·5H₂O and KBr. The identity of the composite was confirmed by several characterization methods, such as X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Oilfield produced wastewater was chosen as the target in this study, due to the toxicity and persistent nature of pollutants [such as, phenol and bisphenol A (BPA)] in this wastewater. Bi₄O₅Br₂/BiOBr displays excellent photocatalytic activity for the degradation phenol and bisphenol A and this is superior to that of Bi₄O₅Br₂ and BiOBr. PL, photocurrent response and electrochemical impedance further confirmed the excellent photocatalytic activity of Bi₄O₅Br₂/BiOBr, and cyclic experiments were conducted to reveal the stability and reusability. The mechanism for the degradation of phenol and bisphenol A was proposed after conducting trapping experiments with Bi₄O₅Br₂/BiOBr. This paper reveals a new approach for the preparation of the Bi₄O₅Br₂/BiOBr composite and the degradation of oilfield produced wastewater by this photocatalyst.