Electrochemical oxidation of lamivudine using graphene oxide and Yb co-modified PbO2 electrodes: characterization, influencing factors and degradation mechanisms

In this work, a new type of graphene oxide and Yb co-modified PbO2 electrode (Yb-GO-PbO2) was prepared by the electrodeposition method. Lamivudine was selected as the model contaminant to evaluate the electro-chemical performance of the Yb-GO-PbO2 electrode, and it was found that the Yb-GO-PbO2 electrode could obviously enhance the degradation of lamivudine compared with the PbO2 electrode. Meanwhile, the Yb-GO-PbO2 electrode was systematically characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), which showed that the Yb-GO-PbO2 electrode processed a denser surface, smaller crystal size, and a greater proportion of hydroxyl oxygen species. Electrochemical measurements demonstrate that the Yb-GO-PbO2 electrode processes many prominent features compared to the PbO2 electrode, such as larger electrochemically active surface area, smaller charge transfer resistance, and higher oxygen evolution potential. The effects of lamivudine initial concentration, current density, electrolyte concentration, and initial pH on the degradation of lamivudine were studied and analyzed. The removal rates of lamivudine and COD reached 99.6% and 65.1%, respectively, when treated for 120 min under optimal process conditions. The electrochemical degradation of lamivudine fitted pseudo-first-order reaction kinetics. The in-termediates of lamivudine degradation were determined using UPLC-MS, and possible degradation pathways of lamivudine were proposed. This paper provides a promising approach for enhancing the electrochemical oxidation performance of PbO2 electrodes by introducing GO and Yb.