Sludge biochar as an electron shuttle between periodate and sulfamethoxazole: The dominant role of ball mill-loaded Mn2O3

Abstract

In this study, a one-step solvent-free method using the ball milling technique was employed to prepare Mn2O3-loaded sludge biochar (BM-SBC/Mn2O3), and it was applied to the efficient activation of periodate (IO4−) to achieve rapid removal of sulfamethoxazole from the water column. A nearly two-fold improvement in the degradation rate of sulfamethoxazole (pseudo-first-order constants from 0.049 to 0.09 min−1) was achieved with only a small loading of Mn2O3 (the mass ratio of Mn2O3 and SBC was 1:6). The BM-SBC/Mn2O3 possessed excellent IO4− activation ability and achieved 95.3% removal efficiency of sulfamethoxazole within 30 min. The removal efficiency of sulfamethoxazole was maximized at an initial pH of 3 and was almost unaffected by the coexisting inorganic anions and humic acid. Mechanistic studies suggested that free radical (•OH) and non-radical pathways were collectively responsible for the removal of sulfamethoxazole, while the non-radical pathway of electron transfer was predominant. Ball milling loading of Mn2O3 improved the degree of defects in the catalyst and enhanced the electron transfer efficiency. This study advances the fundamental understanding of the underlying mechanisms involved in the process of IO4− activation catalyzed by ball milling loaded metal oxides onto sludge biochar.