Insight into electrocatalytic activation of peroxymonosulfate by Ti/MnO2 anode via one-step electrodeposition approach toward degradation of levofloxacin

Abstract

In this study, a Ti/MnO₂ anode (denoted as MnO₂) is facilely prepared via a one-step electrodeposition method and used to construct a combined system for the electrocatalytic degradation of refractory levofloxacin (LFX), in which MnO₂ is utilized for peroxymonosulfate (PMS) activation (MnO₂-EC/PMS). By comparison with other degradation systems without utilization of PMS or MnO₂, the MnO₂-EC/PMS system shows the highest degradation efficiency towards LFX. After optimizing preparation process conditions (concentration of feedstocks and electrodeposition time) and electrocatalytic operation parameters (applied current density, electrode distance, initial pH, initial concentration of LFX and initial concentration of PMS), a higher degradation efficiency reaching 89.00% together with 65.81% removal efficiency for chemical oxygen demand (COD) can be achieved within 120 min. Reactive radical quenching and electrochemical measurements confirmed that ˙OH and SO₄˙⁻ play predominant roles in the degradation of LFX in an indirect degradation process. Additionally, the possible degradation pathway is inferred by identifying intermediates with liquid chromatography–mass spectrometry (LC–MS). In conclusion, this study provides a promising route for the removal of refractory contaminants by electrocatalytic activation of PMS with a cost-effective Mn-based transition metal anode.