Fabrication and characterizations of a novel Ce modified PbO2 electrode with Ti4O7-rGO as the middle layer for degradation of ceftazidime

Abstract

Developing stable and high-performance electrodes for effective removal of antibiotics from wastewater remains a significant challenge. Herein, a novel Ce-doped PbO2 electrode with Ti4O7-reduced graphene oxide as the middle layer (Ti/Ti4O7-rGO/Ce-PbO2) was fabricated through drop-coating and electrodeposition for the electrocatalytic degradation of ceftazidime (CAZ). The prepared Ti/Ti4O7-rGO/Ce-PbO2 electrode exhibited more active sites, higher oxygen evolution potential, and stronger ability for hydroxyl radical (•OH) generation. In the degradation experiments, approximately 100 % of CAZ (30 mg L−1) was degraded by the Ti/Ti4O7-rGO/Ce-PbO2 electrode at 40 mA cm−2 in 0.1 M Na2SO4 solution within 90 min. The quenching test and EPR analysis indicated that the •OH played a pivotal role in the degradation process. A possible degradation mechanism of CAZ, which involved bond breaking, decarboxylation, demethylation, oxidization, and ring-opening, was proposed. The Escherichia coli inhibition experiment showed that the toxicity of CAZ was substantially reduced after electrochemical oxidation. The Ti/Ti4O7-rGO/Ce-PbO2 electrode exhibited a constant degradation efficiency (> 99 %) after 10 consecutive cycles, and its service life can reach 3000 min. Furthermore, CAZ maintained a high removal efficiency in swine wastewater. This study provides a new approach toward fabricating a Ce-PbO2 electrode with Ti4O7-rGO middle layer for the degradation of antibiotics in wastewater.