Non-radical activation of peroxymonosulfate for degradation of antibiotics in saline environments by biochar flakes prepared with molten salt strategy

Due to the serious interference of inorganic salts, it is very important to develop a peroxymonosulfate (PMS) oxidation system that can operate normally and efficiently in saline environments. Herein, the Fe-N-doped biochar flakes (FSBC) derived from sesame powder were developed with the help of molten salt strategy for activating PMS to achieve efficient degradation of tetracycline in salt environment. The effect of calcination temperature on physical and chemical properties was studied to further optimize the performance of the catalyst. FSBC-800 showed the best activation performance for PMS, with a TC removal rate of ∼ 94 % within 10 min. Mechanism research shows that FSBC-800 activates PMS through singlet oxygen (1O2) and electron transfer, so the reaction system is extremely selective and can almost avoid interference from various inorganic ions. The FSBC-800/PMS system can operate efficiently in the coexistence of 8 common anions/cations (0–250 mM), and salinity of 0.1–5.0 wt% has almost no negative impact on the system. In addition, possible degradation pathways of tetracycline were proposed, and the toxicity of intermediate products during the degradation process was evaluated. This study provides a PMS oxidation system with strong selectivity that can cope with various complex saline environments.