State Environmental Protection Key Lab of Environmental Risk Assessment and Control on Chemical Processes, School of Resources & Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
State Environmental Protection Key Lab of Environmental Risk Assessment and Control on Chemical Processes, School of Resources & Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
Sci Total Environ. 2019 Nov 20;692:201-208. doi: 10.1016/j.scitotenv.2019.07.259. Epub 2019 Jul 17.
The widespread occurrence of sulfonamides (SAs) in natural waters, wastewater, soil and sediment has raised increasing concerns about their potential risks to human health and ecological systems. Sulfate radical (SO)-based advanced oxidation processes (SR-AOPs) have become promising technologies to remove such contaminants in the environment. The present study systematically investigated the degradation of four selected SAs with different five-membered heterocyclic rings, namely, sulfamethoxazole (SMX), sulfisoxazole (SIX), sulfathiazole (STZ), and sulfamethizole (SMT), by thermo-activated persulfate (PS) process, and the role of heterocyclic rings was assessed particularly. The results revealed that all the selected SAs could be degraded efficiently by thermo-activated PS process and their decay rates were appreciably increased with increasing temperature. For instance, degradation rates of STZ increased from 0.3 × 10 to 19.5 × 10 min as the temperature was increased from 30 to 60 °C. Under the same experimental conditions, the degradation rates of SAs followed the order of SIX > SMX ≈ STZ > SMT, which was in accordance with decay rates of their R-NH moieties. Kinetic results indicated that five-membered heterocyclic rings could serve as reactive moieties toward SO attack, which were confirmed by frontier electron density (FED) calculations. Based on the transformation products identified by high-resolution mass spectrometry (HR-MS), five different oxidation pathways, including hydroxylation, aniline moiety oxidation, dimerization, sulfonamide bond cleavage, and heterocyclic ring oxidation/cleavage were proposed. Moreover, the degradation efficiency in real surface water (RSW) was found to be slightly slower than that in artificial surface water (ASW), suggesting that SR-AOPs could be an efficient approach for remediation of soil and water contaminated by these SAs.
磺胺类药物（SAs）在天然水、废水、土壤和沉积物中的广泛存在，引起了人们对其对人类健康和生态系统潜在风险的日益关注。基于硫酸根自由基（SO）的高级氧化工艺（SR-AOPs）已成为去除环境中此类污染物的有前途的技术。本研究系统研究了具有不同五元杂环的四种选定磺胺类药物（磺胺甲恶唑（SMX）、磺胺异恶唑（SIX）、磺胺噻唑（STZ）和磺胺甲噻二唑（SMT））通过热激活过硫酸盐（PS）过程的降解情况，并特别评估了杂环的作用。结果表明，所有选定的磺胺类药物均可通过热激活 PS 过程有效降解，其降解速率随温度的升高而显著提高。例如，当温度从 30°C 升高到 60°C 时，STZ 的降解速率从 0.3×10-2 min-1增加到 19.5×10-2 min-1。在相同的实验条件下，磺胺类药物的降解速率顺序为 SIX>SMX≈STZ>SMT，这与它们的 R-NH 部分的衰减速率一致。动力学结果表明，五元杂环可以作为 SO 攻击的反应基团，这通过前沿电子密度（FED）计算得到了证实。基于高分辨率质谱（HR-MS）鉴定的转化产物，提出了五种不同的氧化途径，包括羟化、苯胺部分氧化、二聚化、磺胺键断裂和杂环氧化/断裂。此外，在实际地表水（RSW）中的降解效率发现略慢于人工地表水（ASW），表明 SR-AOPs 可能是修复受这些磺胺类药物污染的土壤和水的有效方法。
