Controllable synthesis of BiVO4 photocatalysts with distinct morphology toward different dyes degradation in the presence of peroxydisulfate

BiVO4 photocatalysts with distinct morphology were solvothermally prepared by regulating the pH of precursor solution. The physicochemical properties of BiVO4 catalysts were characterized using XRD, SEM, EDS, FT-IR and UV-Vis DRS. With the assistance of peroxydisulfate (PDS), as-obtained BiVO4 could effectively degrade the cationic dye rhodamine B (RhB) and the anionic dye methyl orange (MO) under visible-LED-light illumination. RhB degradation obeys the first-order kinetic, while MO degradation complies with the second-order kinetic. Short stick-like BiVO4 (named as BiVO4-1) showed the best RhB degradation efficiency, and sheet-like BiVO4 (named as BiVO4-9) had the highest MO degradation rate. The influence of some important operating factors (PDS dose, BiVO4 dosage, temperature, inorganic anions and humic acid) on the degradation of RhB and MO were discussed. In the BiVO4-1/PDS/Vis system, the free radical pathway (O-2(center dot-), SO4 center dot-, (OH)-O-center dot) and the non-radical pathway (O-1(2) and h(+)) acted together to realize the degradation of RhB; however, in the BiVO4-9/PDS/Vis system, MO degradation was mainly dominated by the non-radical oxidation pathway (O-1(2) and h(+)).