摘要

在本研究中，单过氧单硫酸盐（PMS）系统首次系统地表现为非自由基过程，并且首先通过理论计算和实验检测相结合验证了PMS直接氧化，发现它们选择性地降解磺胺类抗生素（SA）高效率。与其他化合物的可忽略的减少相比，超过95％的选定的SA被PMS单独去除。与甲醇或叔丁醇对SAs降解的微小影响相比，NaN3几乎可以完全猝灭氧化过程，证明非自由基氧化过程（1O2和PMS直接氧化）可能是单独PMS导致SAs降解的原因，而不是常规自由基氧化。然而，可被1O2有效降解的苯酚仅通过PMS单独显示6.2％的去除率，表明1O2的贡献有限。因此，PMS直接氧化将是PMS单独用于高效SA降解的主要非自由基氧化过程。然后电子顺磁共振（EPR）实验也验证了高SAs降解效率归因于PMS直接氧化。此外，密度泛函理论（DFT）计算和SAs途径也间接证实了PMS非自由基氧化，其中SA在苯环上的N原子上选择性地受到攻击，通过PMS直接氧化形成显色产物和磺胺基团的S原子。本研究为PMS自氧化对磺胺类抗生素降解的选择性，性能和机理提供了新的见解。

In this study, peroxymonosulfate (PMS) alone process was systematically demonstrated as nonradical processes for the first time and PMS direct oxidation was firstly verified by the combination of theoretical calculation and experimental detection as well, which were found to selectively degrade sulfonamide antibiotics (SAs) with high efficiency. Compared with the negligible decrease in other compounds, more than 95% of selected SAs were removed by PMS alone. In comparison with the little impacts of methanol or tert-butanol on SAs degradation, NaN3 can almost completely quench the oxidation processes, demonstrating the nonradical oxidation processes (1O2 and PMS direct oxidation) may be responsible for SAs degradation by PMS alone rather than conventional radical oxidation. However, phenol, which can be efficiently degraded by 1O2, only showed 6.2% removal rate by PMS alone, suggesting the limited contribution of 1O2. Thus PMS direct oxidation would be the dominant nonradical oxidation process of PMS alone for efficient SAs degradation. Then electron paramagnetic resonance (EPR) experiments also verified the high SAs degradation efficiency was attributed to PMS direct oxidation. Furthermore, density functional theory (DFT) calculation and SAs pathways also indirectly confirmed PMS nonradical oxidation, where SAs were selectively attacked at the N atom on thebenzene ring to form chromogenic products and S atom of the sulfanilamide groups by PMS direct oxidation. This study gives new insight into selectivity, performances and mechanisms of PMS self-oxidation on sulfonamide antibiotics degradation.

https://www.sciencedirect.com/science/article/pii/S138589471732096X