水体中磺胺甲恶唑在BDD电极体系中的电化学氧化机理

以磺胺甲恶唑(SMX)为研究对象, 采用掺硼金刚石薄膜(BDD)电极电化学氧化法, 研究电流密度和电解质溶液对其降解效果的影响; 用循环伏安扫描和GC-MS测定中间产物, 提出SMX降解的机理。结果表明,BDD电化学氧化SMX的最佳电流密度为20 mA/cm², 最适电解质溶液为0.05 mol/L Na₂SO₄, 此外, 可在50分钟内实现100%的SMX去除, 且去除过程满足一级反应动力学方程。低电流密度下, SMX可发生直接电化学氧化,通过苯胺基失去电子生成二聚物; 高电流密度下, SMX以间接?OH氧化为主, 可能的降解途径有两条, 分别为?OH攻击导致S-N键断裂和?OH攻击杂环使得苯环开裂, 生成小分子羧酸, 最终矿化成CO₂, H₂O以及无机离子。

Electrochemical Oxidation Mechanism of Sulfamethoxazolein BDD Electrode System

By choosing sulfamethoxazole as the typical pollutant, this paper studied influences of current densityand electrolyte solution on electrochemical oxidation by BDD electrode. The degradation mechanism wasillustrated through cyclic voltammetry (CV) and intermediates detection using GC-MS. As results, the optimalconditions for SMX degradation were 20 mA/cm² for current density and 0.05 mol/L Na₂SO₄ for electrolytesolution, at which the removal efficiency of SMX was 100% within 50 min, and the degradation kinetics followedpseudo-first order model. At lower current density, the SMX dimer was fabricated due to the electron losen ofphenylamino group, which could be directly electrochemical oxidized. While at higher current density, the indirectoxidation by ?OH was the main process. Two possible pathways could occur, one way was conducted due to thebreak of S-N bond, and the other was the attack to the heterocyclic ring resulting in the breakage of benzene ring.Finally, SMX was mineralized to CO₂, H₂O and inorganic ions.