Iron-manganese oxide loaded sludge biochar as a novel periodate activator for thiacloprid efficient degradation over a wide pH range

In this study, a novel iron-manganese oxide-loaded sludge-based biochar was prepared by coprecipitation route for efficient removal of thiacloprid (TCP) from the aqueous environment with activating periodate (PI). The effects of operational parameters on the degradation of thiacloprid, including catalyst dosage, periodate concentration, and initial pH, were evaluated. Excessive concentrations of HCO3– ions had a significant inhibitory effect on the reaction system, while Cl-, SO42- ions, and humic acid presented negligible effects. More than 80% removal rate of TCP even in natural water matrixes and more than 92% removal in a wide pH range of 3–11 were achieved. The reactive radicals identified in the Fe/Mn-SBC/PI heterogeneous system were IO3• and •OH based on free radical quenching experiments and EPR technology. The reaction mechanism dependent on iron and manganese oxides has been proposed synergistically based on various characterization and experimental results. The enhancement of activation properties could be attributed to the enhanced electron transfer between iron and manganese oxides. A possible TCP degradation pathway was presented and main products were provided. This study provides a novel insight into the application of iron-manganese oxide-loaded sludge biochar on periodate activation for pollutant elimination.