[Electrocatalytic Oxidation of Sulfadiazine with Ni-Doped Sb-SnO₂ Ceramic Ring Particle Electrode]

The excessive use and abuse of antibiotics has brought about serious threats to water environmental safety and human health. It is necessary to develop efficient, cheap, and environmentally friendly treatment technologies for antibiotics. In this work, a Ni-doped Sb-SnO₂ microporous ceramic ring particle electrode was prepared by the dipping method and characterized by scanning electron microscopy, energy dispersion spectroscopy, and X-ray diffraction. The electrocatalytic oxidation ability and kinetic characteristics of sulfadiazine (SDZ) were studied using the prepared electrode, and the degradation pathways of SDZ were analyzed preliminarily. The results showed that Ni and Sb-SnO₂ crystals were loaded on the particle electrode surface, which is beneficial for electron transfer and SDZ adsorption and improvement of electrocatalytic oxidation efficiency. Under the conditions of 0.02 mol·L^-1 NaCl solution (pH 8), 15 mA·cm^-2 of current density, and 15 g particle electrode, 50 mg·L^-1 SDZ could be completely removed on the three-dimensional electrode within 15 min. The removal efficiency of TOC in the reaction solution reached 80.8% for 3 h degradation and was 17.6% higher than that with two-dimensional electrode. The kinetic process of the electrocatalytic oxidation could be well described by the first-order reaction kinetic model, and the rate constant was 0.329 min^-1. The degradation products of SDZ were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the possible pathways of electrocatalytic degradation mainly include the fractures of S-N bond on sulfamido and C-N bond on pyrimidine ring, desulfonation, deamination, and·OH oxidation.