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 beta-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 center dot OH and SO42-, 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 center dot 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.