改性二氧化铅阳极氧化去除人工甜味剂纽甜动力学及机理研究

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

  • 摘要: 近年来,人工甜味剂在各类环境介质中频繁检出,其不确定的环境行为和毒性引起广泛关注。传统污水厂对甜味剂的处理能力有限,因此亟需开发新的处理技术以实现其有效降解。本文使用铈改性二氧化铅阳极(Ti/SnO2-Sb/Ce-PbO2)氧化体系降解人工甜味剂纽甜,研究了电流密度、溶液pH、溶液温度、污染物浓度、 \textC\textl^- 和 \textHC\textO_\text3^- 对纽甜降解动力学的影响,通过高效液相色谱(HPLC)分析检测纽甜浓度,采用高效液相色谱-质谱法(HPLC-MS)鉴定纽甜的降解产物,预测纽甜降解路径并探究纽甜降解机理。结果表明:Ti/SnO2-Sb/Ce-PbO2阳极氧化体系可在2mA/cm2低电流密度下高效降解纽甜,速率常数为0.20min−1。该体系在pH 5~9范围内均能实现对纽甜86%以上的降解。此外,水温的升高会加速该体系对纽甜的降解,在40℃时降解动力学常数为0.27min−1。Ti/SnO2-Sb/Ce-PbO2阳极氧化体系的氧化能力强,在纽甜浓度达到40mg/L时,其降解半衰期仍可达4.95min。Ti/SnO2-Sb/Ce-PbO2阳极氧化体系主要通过自由基途径降解纽甜,其降解产物的生物富集性、致突变性等毒性均有所降低。Ti/SnO2-Sb/Ce-PbO2阳极氧化体系拥有较强的抗离子干扰能力和稳定性, \textHC\textO_\text3^- 会对纽甜的降解产生轻微的抑制作用,但当其浓度达25mmol/L时,纽甜降解效率仍在72%以上; \textC\textl^- 的存在则会加速纽甜的降解;该体系循环5次后降解效率几乎不变,动力学常数大于0.20min−1。研究认为Ti/SnO2-Sb/Ce-PbO2阳极氧化体系可对人工甜味剂高效地降解和脱毒,拥有良好的环境适应性和稳定性,具有较高的实际应用潜力。

     

    Abstract: 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.

     

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