Dechlorination-Hydroxylation of Atrazine to Hydroxyatrazine with Thiosulfate: A Detoxification Strategy in Seconds.
Dechlorination-Hydroxylation of Atrazine to Hydroxyatrazine with Thiosulfate: A Detoxification Strategy in Seconds.
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DOI：
10.1021/acs.est.8b06351
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发表时间：
2019-02
影响因子：
11.4
通讯作者：
Yi Mu;Guangming Zhan;Cuimei Huang;Xiaobing Wang;Zhihui Ai;J. Zou;S. Luo;Lizhi Zhang
中科院分区：
文献类型：
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作者：
Yi Mu;Guangming Zhan;Cuimei Huang;Xiaobing Wang;Zhihui Ai;J. Zou;S. Luo;Lizhi Zhang
将阿特拉津羟基化为无毒的羟基阿特拉津是修复阿特拉津污染土壤和水体的有效方法。然而，以往的研究表明，羟基化不是阿特拉津降解的主导途径在羟基自由基产生系统，如芬顿反应，臭氧化和UV/H2 O2。本文报道了在室温下，pH ≤ 4时，硫代硫酸钠可使莠去津快速羟基化为羟基莠去津。高分辨质谱和同位素实验结果表明，阿特拉津的羟基化反应包括亲核取代反应和水解反应。HS_2 O_3 ~-仅在pH ≤ 4时以硫代硫酸盐的形式首先进攻阿特拉津中与氯相连的C原子，使阿特拉津脱氯，生成C_8H_（14）N_5S_2 O_3 ~-。随后，C8 H14 N5 S2 O3-的S-S键容易断裂，形成SO 3和C8 H14 N5 S-。接着，C8 H14 N5 S-水解生成羟基阿特拉津和H2S。最后，SO_3和H_2S原位歧化反应在莠去津与硫代硫酸盐的羟基化过程中产生S_0。本研究阐明了降解途径对污染物去除的重要性，也为阿特拉津的快速非氧化解毒提供了一种策略。
Hydroxylation of atrazine to nontoxic hydroxyatrazine is generally considered an efficient detoxification method to remediate atrazine-contaminated soil and water. However, previous studies suggested that hydroxylation was not the dominant pathway for atrazine degradation in the hydroxyl radical-generating systems such as Fenton reaction, ozonation and UV/H2O2. Herein we report that the addition of sodium thiosulfate can realize rapid hydroxylation of atrazine to hydroxyatrazine at pH ≤ 4 under room temperature. High resolution mass spectra and isotope experiments results revealed that the hydroxylation of atrazine was involved with nucleophilic substitution and subsequent hydrolysis reaction as follows. HS2O3-, as a species of thiosulfate only at pH ≤ 4, first attacked C atom connecting to chlorine of atrazine to dechlorinate atrazine and produce C8H14N5S2O3-. Subsequently, the S-S bond of C8H14N5S2O3- was cleaved easily to form SO3 and C8H14N5S-. Next, C8H14N5S- was hydrolyzed to generate hydroxyatrazine and H2S. Finally, the comproportionation of SO3 and H2S in situ produced S0 during hydroxylation of atrazine with thiosulfate. This study clarifies the importance of degradation pathway on the removal of pollutants, and also provides a nonoxidative strategy for atrazine detoxification in seconds.