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

The sillenite phase Bi12.7Co0.3O19.35 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 Bi12.7Co0.3O19.35 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 Bi12.7Co0.3O19.35. 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. Bi12.7Co0.3O19.35 has potential application prospects in the degradation of organic pollutants with high catalytic efficiency and repeatability.