Kinetics and Mechanism of Neotame Removal by Anodic Oxidation of Modified Lead Dioxide

In recent years, artificial sweeteners have been frequently detected in various environmental media, raising widespread concerns about the uncertainty of their environmental behavior and toxicity. Traditional sewage treatment plants have limited capacity to effectively degrade these sweeteners, necessitating the development of new treatment technologies for their efficient degradation. A cerium-modified lead dioxide anode (Ti/SnO₂-Sb/Ce-PbO₂) oxidation system was utilized to degrade the artificial sweetener neotame. The effects of current density, solution pH, temperature, concentration, as well as the presence of \textC\textl^- and \textHC\textO_\text3^- ions on the degradation kinetics of neotame were investigated. Neotame concentration was analyzed using high performance liquid chromatography (HPLC), while high performance liquid chromatography-mass spectrometry (HPLC-MS) was employed to identify the degradation intermediates. The degradation pathway of neotame was predicted, and the degradation mechanism was explored. The results indicated that the Ti/SnO₂-Sb/Ce-PbO₂ anode oxidation system could efficiently degrade neotame at a low current density of 2mA/cm², with a rate constant of 0.20min⁻¹. The system achieved more than 86% degradation of neotame within the pH range of 5 to 9. Furthermore, an increase in water temperature accelerated the degradation process, with a degradation rate constant of 0.27min⁻¹ observed at 40℃. The oxidation system exhibited strong oxidative capability, and even at a neotame concentration of 40mg/L, the degradation half-life period was still 4.95min⁻¹. The primary degradation pathway of neotame in the Ti/SnO₂-Sb/Ce-PbO₂ system was through free radical mechanisms, with the degradation products showing reduced bioaccumulation, mutagenicity, and other toxicities. The Ti/SnO₂-Sb/Ce-PbO₂ anode oxidation system demonstrated a strong resistance to ionic interference and stability. While the presence of \textHC\textO_\text3^- ions exerted a slight inhibitory effect on neotame degradation, at a concentration of 25mmol/L, the degradation efficiency remained above 72%. In contrast, the presence of \textC\textl^- ions accelerated the degradation process. After five cycles, the degradation efficiency of the system remained almost unchanged, with the kinetic constant exceeding 0.2min⁻¹. It is concluded that the Ti/SnO₂-Sb/Ce-PbO₂ anode oxidation system is highly effective in degrading and detoxifying artificial sweeteners, exhibiting excellent environmental adaptability and stability, and holding significant potential for practical applications. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202503170046.