Persulfate activation with nitrogen and sulfur co-doped porous biochar to remove thiamethoxam: A combination of radicals and nonradicals

Nitrogen and sulfur co-doped porous biochar (NSBC) was synthesized through the pyrolysis of Phytolacca acinose Roxb biomass in the presence of sodium bicarbonate and L-cysteine monohydrochloride. The resulting NSBC exhibited exceptional adsorption and catalytic degradation properties, demonstrating remarkable efficiency in the oxidation and degradation of thiamethoxam (THM) solutions. To elucidate the underlying oxidation mechanism, a combination of radical quenching techniques and advanced in situ electron paramagnetic resonance (EPR) spectroscopy was employed. The experimental findings revealed that the enhanced oxidation efficiency observed in the NSBC+PS system could be attributed to the synergistic interaction between singlet oxygen (1O2) and Reactive Oxygen Species (ROS). The introduction of nitrogen and sulfur doped facilitated the formation of point defects, which in turn promoted the generation of 1O2. Furthermore, the degradation pathways of THM intermediates were successfully elucidated. This study presents a novel approach for the synthesis and application of high-quality catalysts in water treatment.