New theoretical investigation of mechanism, kinetics, and toxicity in the degradation of dimetridazole and ornidazole by hydroxyl radicals in aqueous phase.
New theoretical investigation of mechanism, kinetics, and toxicity in the degradation of dimetridazole and ornidazole by hydroxyl radicals in aqueous phase.
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水相中羟基自由基降解二甲硝唑和奥硝唑的机理、动力学和毒性的新理论研究。
DOI：
10.1016/j.jhazmat.2021.126930
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发表时间：
2021-08
影响因子：
13.6
通讯作者：
Min Ruan
中科院分区：
文献类型：
--
作者：
Junfang Yao;Yizhen Tang;Yunju Zhang;Wenzhong Wu;Jingyu Sun;Min Ruan
二甲硝咪唑（DMZ）和奥硝唑（ONZ）已被广泛用于治疗厌氧菌和原虫感染。DMZ/ONZ残留物在水环境中持久存在。通过量子化学方法评估了羟基引发氧化（主要的DMZ/ONZ降解方法）的机制和动力学。·OH诱导的DMZ和ONZ降解具有许多共同的机理和动力学特征。最可行的降解途径涉及形成OH-咪唑加合物和NO2。OH-咪唑加合物随后降解为双·OH咪唑中间体。298 K时，DMZ和ONZ的·OH降解速率系数分别为4.32 × 109 M − 1 s − 1和4.42 × 109 M − 1 s − 1。在298 K下，用浓度为10−9-10− 18 mol L− 1的·OH处理的DMZ和ONZ的寿命分别为τDMZ= 0.231-2.31 × 108 s和τONZ= 0.226-2.26 × 108 s。毒性评价结果表明，DMZ和ONZ的第一次降解产物对水生生物的毒性增强，而第二次降解产物对水生生物的毒性较小。部分转化产物仍呈发育毒性或致突变性阳性。
Dimetridazole (DMZ) and ornidazole (ONZ) have been widely used to treat anaerobic and protozoal infections. The residues of DMZ/ONZ persist in the water environment. The mechanisms and kinetics of hydroxyl-initiated oxidation, the primary DMZ/ONZ degradation method, were evaluated by quantum chemical methods.·OH-induced degradation of DMZ and ONZ shared many mechanistic and kinetic characteristics. The most feasible degradation pathway involved forming OH-imidazole adducts and NO2. The OH-imidazole adducts were subsequently degraded into double·OH imidazole intermediates. The rate coefficients for·OH degradation of DMZ and ONZ were 4.32 × 109M−1s−1and 4.42 × 109M−1s−1at 298 K, respectively. The lifetimes of DMZ and ONZ treated with·OH at concentrations of 10−9–10−18mol L−1at 298 K wereτDMZ= 0.231–2.31 × 108s and τONZ= 0.226–2.26 × 108s, respectively. Toxicity assessment showed that the first degradation products of DMZ and ONZ exhibited enhanced aquatic toxicity, whereas most of the secondary degradation products were not harmful to aquatic organisms. Some of transformation products were still developmental toxicant or mutagenicity positive.