Co/La modified Ti/PbO₂ anodes for chloramphenicol degradation: Catalytic performance and reaction mechanism

Chloramphenicol (CAP) is widely used in daily life, and its abuse hurts human health, so a suitable method is needed to solve the problem. In this study, the Ti/PbO₂ electrodes prepared by the electroplating method were characterized. The CAP degradation effect and mechanism were investigated. It was shown that the electrode surface had a dense plating with a characteristic peak of β-PbO₂ as the active component. The electrode had an oxygen precipitation potential of 1.695 V and a corrosion potential of 0.553 V, and a long service life (505.4 d). The degradation of CAP at Ti/PbO₂ electrode followed a first-order kinetic reaction. The optimal degradation conditions (current density of 12.97 mA cm^-2, electrolyte concentration of 50 mM, and solution pH of 6.38) were obtained by the response surface curve method. The degradation rate of CAP was 99.0% at 60 min. The results showed that the reactive groups leading to CAP degradation were mainly ·OH and SO₄^2-, and only a tiny portion of CAP was directly oxidized on the electrode surface. The addition of Cl^- favored the degradation of CAP, but reduced the mineralization rate. LC-MS analysis showed that ·OH mainly attacked the asymmetric centers (C1, C2) of weakly bound hydrogen atoms, resulting in underwent addition and substitution reactions. CAP was converted into two substances with m/z = 306 and m/z = 165. Finally, inorganic substances such as CO₂ and H₂O were generated. This study provided a new idea for preparing Ti/PbO₂ electrode with high performance and the safe and efficient degradation of CAP.