Highly Efficient Peroxymonosulfate Activation by Molten Salt-Assisted Synthesis of Magnetic Mn–Fe<sub>3</sub>O<sub>4</sub> Supported Mesoporous Biochar Composites for SDz Degradation
Qiannan Huang, Wenjing Zhang, Feng Li, Min Zhang, Qiuye Li, Jianjun Yang
Abstract
Bimetallic iron manganese oxide/biochar nanocomposites (KFMNBC) were synthesized by the KCl molten salt method and achieved a sulfadiazine (SDz) degradation rate of 100% and a mineralization rate of 78.8% within 24 min by activating peroxymonosulfate (PMS). Compared to single biochar and bimetallic oxides synthesized without KCl, KFMNBC exhibited 17.65 and 13.50 times higher degradation rates, respectively. The KCl molten salt method is conducive to the formation of mesoporous biochar structural materials with a large specific surface area and surface carbonyl functional groups, thereby providing more active sites and facilitating the formation of singlet oxygen atoms ( 1 O 2 ). Moreover, Fe–Mn oxides with high crystallinity and dispersion can provide more reaction sites for SDz degradation and improve the stability of the catalyst. The results of free radical quenching experiments and EPR characterization confirmed that the main active species are surface-bound free radicals (•SO 4 – and •OH), high-valence metal Fe IV /Mn V, and 1 O 2 . The KFMNBC catalyst maintains good degradation performance in the pH range (3.0–9.0) under the coexistence of inorganic anions (Cl –, NO 3 –, and H 2 PO 4 – ), demonstrating good anti-interference ability and great potential for practical applications.