DEET degradation in UV/monochloramine process: Kinetics, degradation pathway, toxicity and energy consumption analysis
DEET degradation in UV/monochloramine process: Kinetics, degradation pathway, toxicity and energy consumption analysis
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UV/一氯胺过程中的 DEET 降解：动力学、降解途径、毒性和能耗分析
DOI：
10.1016/j.chemosphere.2020.126062
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发表时间：
2020
期刊：
影响因子：
8.8
通讯作者：
Li Qiongsong
中科院分区：
文献类型：
--
作者：
Zhu Tianxin;Deng Jing;Xu Mengyuan;Cai Anhong;Ye Cheng;Li Jun;Li Xueyan;Li Qiongsong
系统研究了UV/NH_2Cl（UV/NH_2Cl）工艺对水中避蚊胺（DEET）的降解。避蚊胺对紫外线光解和氯胺化反应具有抗性，而紫外线照射与氯化铵同步结合可有效消除避蚊胺，产生的羟基自由基和活性氯物种可有效消除避蚊胺。前者在DEET降解中起着关键作用，而后者的贡献可以忽略不计。在所有实验条件下，避蚊胺在UV/NH 2Cl过程中的降解遵循伪一级动力学模型。水质参数的影响是复杂的。降低溶液pH值和提高水温都有利于DEET的去除。硫酸盐、腐殖酸和富里酸的存在促进了降解，而碳酸氢盐和高浓度氯化物的引入则抑制了去除。结合QTOF/MS分析和密度泛函理论计算，提出了避蚊胺在UV/NH 2Cl工艺中的可能降解途径，主要涉及C-N键断裂、脱烷基化、单羟基化和多羟基化。随着辐照时间的延长，反应液的急性毒性呈现先增大后减小的趋势，定量构效关系分析可以很好地说明这一点。以单位电能为能耗指标，确定了最佳工艺条件：紫外线能量密度为369.9-493.2 mJ·cm（-2），氯化铵投加量为5-20 mg·L-1。(C)2020爱思唯尔有限公司保留所有权利。
The degradation of N,N-diethyl-meta-toluamide (DEET) in aqueous solution by the UV/monochloramine (UV/NH2Cl) process was examined systematically in this study. DEET was resistant to UV photolysis and chloramination, while the synchronous combination of UV irradiation and NH2Cl can effectively eliminate DEET, which was caused by the generation of hydroxyl radicals and reactive chlorine species. The former played the critical role in DEET degradation, while the contribution of the latter can be ignored. Under all investigated experimental conditions, DEET degradation in the UV/NH2Cl process followed the pseudo-first-order kinetic model. The water quality parameters exerted the complicated impact. Reducing solution pH and raising water temperature both favored the DEET removal. The presence of sulfate, humic acid and fulvic acid accelerated the degradation, while the introduction of bicarbonate and high-concentration chloride retarded the removal. The plausible degradation pathways of DEET in the UV/NH2Cl process were proposed through the combination of QTOF/MS analysis and DFT calculation, and mainly involved in the cleavage of C-N bond, dealkylation, mono- and polyhydroxylation. The acute toxicity of reacted solution underwent a trend of first increasing and then decreasing with the prolonged irradiation time, which can be well illustrated by quantitative structure-activity relationship analysis. Electrical energy per order was employed to determine the energy consumption and the optimal conditions were determined as UV fluence of 369.9-493.2 mJ cm(-2) and NH2Cl dosage of 5-20 mg L-1. (C) 2020 Elsevier Ltd. All rights reserved.