Efficient synthesis of iron oxide-biochar nanocomposites from iron-rich waste for enhanced tetracycline degradation via peroxymonosulfate activation

Every year, billions of tons of iron-rich waste are generated globally, presenting a valuable resource for synthesizing iron-based catalysts. In this study, we synthesized iron oxide-biochar (Iron Oxide@Biochar) nanocomposites by ball milling a combination of tea leaves and iron-rich waste. These nanocomposites were found to be highly efficient activators of peroxymonosulfate (PMS) for degrading tetracycline (TC). Particularly, biochar-encapsulated disposable instant hot packs (DHP/BC) achieved a TC removal efficiency of 94.7% under optimal conditions, exhibiting excellent stability and strong anti-interference capabilities. Our analysis revealed that TC degradation predominantly occurred via a non-radical pathway involving singlet oxygen ( 1 O 2 ) and electron transfer , with free radicals (·OH and SO 4 ·- ) playing a secondary role. This research not only offers an economical and efficient solution for recycling solid waste and reusing natural biochar but also introduces a sustainable and environmentally friendly method for preparing catalysts for pollutant degradation, thus achieving the dual goals of “resource recycling” and “treating waste with waste."