Electrochemical activation of peroxymonosulfate at Ti/La2O3-PbO2 anode to enhance the degradation of typical antibiotic wastewater

In this study, a novel electrochemically anodic activated peroxymonosulfate (PMS) system ((Ti/La2O3-PbO2)EA-PMS) was constructed by combining the Ti/La2O3-PbO2 anode with PMS. The prepared (Ti/La2O3-PbO2)EA-PMS system removed 98.07% of cefadroxil (CFR), which was 17.85% higher than that of the single electrochemical (EC) system and 78.10 % higher than that of the PMS system. In addition, the (Ti/La2O3-PbO2)EA-PMS system showed the satisfactory applicability to the single and mixed wastewater of CFR, tetracycline (TC), and levofloxacin (LFX) with the degradation rate greater than similar to 95%, the stability and degradation performance was much better than the conventional PMS activation systems. The excellent degradation performance was partially attributed to the excellent physico-chemical and electrochemical performances of Ti/La2O3-PbO2 anode, such as the rougher and compact surface, faster mass and electron transfer performance, the higher proportion of the adsorbed hydroxyl oxygen (O-ads) for the production of reactive oxygen species (ROS) and a higher oxygen evolution overpotential to inhibit the occurrence of the electrolysis of water. In addition, the collaboration of Ti/La2O3-PbO2 anode and PMS activation produced a synergistic effect on the degradation of antibiotics, which mainly reflected at the direct-electron-transfer controlled non-free radical oxidation occurred on the surface of Ti/La2O3-PbO2 anode and the free radical oxidation dominated by adsorbed center dot OH (PbO2(center dot OH)), free hydroxyl radical (center dot OH) and sulfate radical (SO4 center dot-). Moreover, the effects of operating parameters (PMS concentration, current density and initial pH value) and water background components on the removal of CFR by (Ti/La2O3-PbO2)EA-PMS system were investigated. The possible degradation pathways of CFR were also speculated. The electrochemically anodic activated PMS system based on Ti/La2O3-PbO2 anode was expected to provide an efficient technology for the treatment of actual pharmaceutical wastewater and this work also provided a significant reference for the design of novel advanced oxidation process combined with PMS (AOP-PMS) systems.

Automated summary

In this study, a novel electrochemically activated peroxymonosulfate system was developed and investigated for the degradation of antibiotics. The results showed that the system exhibited excellent degradation performance and stability, making it a promising technology for the treatment of pharmaceutical wastewater.