Efficient Water Disinfection via Photocatalytic Oxidation Process Mediated by WO3/BiOBr@Si Composite

Developing green water disinfection technology has been attracting much attention all over the world. In this work, a WO3/BiOBr@Si composite was obtained through the solvothermal process, which exhibited denser and fuller intersecting petal-like spheres (1–3 μm in diameter) and retained its 3D sheet-like pore structure. The optical and electrochemical analysis demonstrated that the doped Si showed insignificant improvement in UV-Vis light absorption but greatly promoted the electron-hole separation efficiency and charge transfer capability on the surface of the catalyst at a 4.6 wt% Si doping dosage, resulting in an excellent performance in the inactivation of Escherichia coli (E. coli) under the irradiation of visible light. Under the optimal conditions (0.5 g/L of WO3/BiOBr@Si dosage, 107 CFU mL−1 of E. coli concertation, and 30 min of treating time), the largest log value decline (6.6) occurred with WO3/[email protected], which was 3.3 and 1.8 times larger than those of BiOBr (2.0) and WO3/BiOBr (3.7). According to the TEM, SEM, EDS, XRD, FTIR, and XPS analyses, in the photocatalytic system, the hole (h+) and •OH were the main species for inactivating E. coli cells. These oxidizing species could attack the components on the surface of cells (such as the hydroxyl, carbonyl, ester, and amide groups of polysaccharides (PS) and proteins (PT)), resulting in the inactivation and destruction of the cell membranes and leakage of intracellular substances. The findings will provide a significant guide for developing an efficient catalyst for the green water disinfection process.