Ball-milled pyrite@biochar induced percarbonate activation for sustainable degradation of antibiotic norfloxacin at inherent pH environment

Advanced oxidation processes utilizing percarbonate (SPC) have garnered considerable interest in the realm of water purification, but the all-encompassing constraint on pH conditions largely hindered its environmental applications. Here, a combination process of ball-milled pyrite@biochar and SPC was constructed to accelerate the degradation of norfloxacin (NOR) at an inherent pH environment. Results showed that the ball-milled pyrite@biochar + SPC system accomplished almost complete removal of NOR within 60 min, demonstrated excellent pH resilience ranging from pH 3.0 to 10.0, and manifested over 90 % NOR removal in cycle operation. The main mechanism of NOR removal encompassed both adsorption and oxidation processes. The NOR initially adhered to the ball-milled pyrite@biochar interface. Then, the interaction of the ball-milled pyrite@biochar and SPC yielded a multitude of reactive oxygen species (ROS), such as •OH, O2•−, and 1O2, along with electron complexes. The enhanced performance of SPC activated by the ball-milled pyrite@biochar could essentially be attributed to the greater Fe3+/Fe2+ circulation and better electron utilization efficiency through the existence of sulfur species and oxygen-containing functional groups. Accordingly, the regenerated Fe2+ was able to rapidly activate SPC for the production of ROS and electron complexes. Moreover, three possible NOR degradation pathways were put forward. It was illustrated that the application of the ball-milled pyrite@biochar + SPC could effectively reduce the ecotoxicity of NOR in wastewater. Overall, this study established a solid foundation for the implementation of ball-milled pyrite@biochar + SPC system in efficient water purification process.