Enhanced photocatalytic degradation of imidacloprid and RhB by the precursor derived Bi12.7Co0.3O19.35 under different pH value

The sillenite phase Bi_12.7Co_0.3O_19.35 was prepared successfully by pyrolysis of the BiCo-based metal coordination polymer (BiCo-MCP) as precursor. The preparation was studied under varied temperatures from 600 to 700 °C and different reaction time. SEM images showed the diverse morphologies including amorphous, spindle and flake particle shapes obtained under different conditions. Among them, the spindle particles of pure phase Bi_12.7Co_0.3O_19.35 displayed superior catalytic activity for degradation of imidacloprid and RhB under visible light. The pH of the wastewater was found to have significant influence on the photocatalytic performance of Bi_12.7Co_0.3O_19.35. When pH < 1.91 or pH > 11.0, the photocatalytic degradation rate of imidacloprid pesticide wastewater reached more than 96% for 4 h and when pH < 2.4, the degradation effect of RhB dye could achieve 100% degradation within 30 min. The degradation products of imidacloprid changed with different pH values of wastewater. Two different catalytic mechanisms are proposed according to the capture experiment. Bi_12.7Co_0.3O_19.35 has potential application prospects in the degradation of organic pollutants with high catalytic efficiency and repeatability.