Mechanistic Insights and Performance Evaluation of ZnFe-Modified Bovine Manure Biochar in Activating Peroxymonosulfate for Efficient Thiamethoxam Degradation: A Combined DFT Calculation and Degradation Pathway Analysis

The study explored the degradation of thiamethoxam (THM) in water using modified bovine manure biochar as a catalyst for the first time, due to its potential harm to living organisms and frequent detection in natural water bodies. Experimental findings revealed that the rate constants for peroxymonosulfate (PMS)-catalyzed THM degradation by bovine manure biochar modified with ZnCl2 and K2FeO4 (ZnFeBC) increased by 76.78 times compared to unmodified biochar (BC), achieving a 100% degradation rate within 60 min. ZnFeBC exhibited excellent PMS activation performance across various pH levels. XPS characterization and Density Functional Theory (DFT) calculations have revealed that Fe element cycling occurs on the ZnFeBC surface, resulting in increased charge transfer rates at the reaction interface. The main active sites responsible for PMS activation were found to be Fe0 and Fe3O4. The degradation mechanism of THM by the ZnFeBC/PMS system involved SO4 center dot-, center dot OH, 1O2 and electron transfer. This catalyst demonstrated strong pH adaptability and outstanding catalytic degradation capabilities for various pollutants, making it highly suitable for widespread wastewater treatment applications, while also providing a new way for resource reutilization of bovine manure.