A novel layered Ti/CoSnO3-C/PbO2 anode for activation of peroxymonosulfate toward efficient electrocatalytic degradation of levofloxacin

A novel Ti/CoSnO3-C/PbO2 (TCCP) composite layered anode was constructed by sequentially depositing the CoSnO3-C composite as interface layer on Ti matrix (TCC) via immersion pyrolysis technique and then PbO2 top layer via one-step electrodeposition method, which was utilized for electrochemically activating PMS (TCCP-EC/PMS) to degrade levofloxacin (LFX). Initially, the TCCP anode was systematically characterized with SEM, EDS, XRD, FT-IR, XPS and electrochemical tests. Importantly, the above TCCP-EC/PMS possesses higher electrocatalytic properties toward LFX removal than those of other systems including PMS alone, Ti/PbO2 electrocatalysis without PMS (TP-EC), Ti/PbO2 for activating PMS (TP/PMS), TCCP electrocatalysis without PMS (TCCP-EC), TCCP+PMS (TCCP/PMS). The optimal TCCP-EC/PMS delivers the maximum degradation efficiency of LFX similar to 94.9 % together with the removal rate of COD achieving 77.5 % and the used TCCP anode has good reusability for manifold cycles. The higher electrochemical properties of TCCP than TCC and TP can be mainly responsible for the higher degradation rate of LFX including reduced charge transfer resistance, enhanced electroactive area, and elevated oxygen evolution potential. Moreover, the TCCP demonstrates the highest current efficiency (CE) and lowest electrochemical energy consumption (EEC). The radical capturing assays coupled with electron paramagnetic resonance (EPR) tests reveals that the predominant reactive oxidative species (ROS) are center dot OH, SO4 center dot- and O-2(center dot-). Furthermore, the potential degradation pathway is revealed through identifying the intermediates of LFX using liquid chromatography-mass spectrometry (LC-MS) technology. Consequently, this work provides a novel strategy by introducing composite interlayer to regulate the electrocatalytic property of PbO2 toward antibiotic removal via PMS activation.