Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, PR China.
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, PR China; Beijing Key Laboratory of Radioactive Wastes Treatment, Tsinghua University, Beijing, 100084, PR China.
Chemosphere. 2022 Jan;287(Pt 4):132365. doi: 10.1016/j.chemosphere.2021.132365. Epub 2021 Sep 28.
Chloroaniline is a typical organic pollutant in chemical wastewater, which cannot be effectively removed in conventional wastewater treatment processes. In this study, ionizing radiation was used as advanced treatment process to degrade 2-chloroaniline (2-CA). The results showed that 10 mg/l of 2-CA could be completely degraded at 1 kGy. The required dose for completely degrading 2-CA by radiation increased when its initial concentration increased. Solution pH affected 2-CA degradation by changing the radiation-chemical yield of reactive species. Chloride ions (10 and 100 mM) had not obvious influence on 2-CA degradation. Hydrogen radicals, hydrated electrons and hydroxyl radicals, all contributed to the degradation of 2-CA, but with different degradation mechanisms. Hydrogen radicals and hydrated electrons could initiate reductive dechlorination of 2-CA, while hydroxyl radicals can degrade 2-CA by hydroxylation. 6-amino-1,4-cyclohexadiene and chlorobenzene were the main intermediate products of 2-CA degradation in the hydrogen radicals or hydrated electrons dominant process; while o-hydroxyaniline and nitroso-chlorobenzene were the main intermediate products in the hydroxyl radicals dominant process. The solution toxicity after radiation treatment varied with the initial concentration of 2-CA and the absorbed dose. In the actual chemical wastewater, 2-CA can be effectively removed by radiation, even in the presence of high concentration of chloride ions (about 2800 mg/l). The solution toxicity of actual wastewater decreased with the increase of adsorbed dose. This study provided an insight into the 2-CA degradation by radiation, and demonstrated that radiation could be an alternative option for the treatment of chloroaniline-containing chemical wastewater.
氯苯胺是化学废水中的一种典型有机污染物，在常规废水处理过程中无法有效去除。本研究采用电离辐射作为高级处理工艺来降解 2-氯苯胺（2-CA）。结果表明，在 1 kGy 时，10 mg/L 的 2-CA 可完全降解。当 2-CA 的初始浓度增加时，完全降解所需的辐射剂量增加。溶液 pH 通过改变反应性物质的辐射化学产率来影响 2-CA 的降解。氯离子（10 和 100 mM）对 2-CA 降解没有明显影响。氢自由基、水合电子和羟基自由基都有助于 2-CA 的降解，但降解机制不同。氢自由基和水合电子可以引发 2-CA 的还原脱氯，而羟基自由基可以通过羟化作用降解 2-CA。6-氨基-1,4-环己二烯和氯苯是 2-CA 在氢自由基或水合电子主导过程中降解的主要中间产物；而邻羟基苯胺和亚硝基氯苯是羟基自由基主导过程中的主要中间产物。辐射处理后溶液的毒性随 2-CA 的初始浓度和吸收剂量的变化而变化。在实际的化学废水中，即使存在高浓度的氯离子（约 2800 mg/L），辐射也可以有效地去除 2-CA。实际废水的溶液毒性随吸附剂量的增加而降低。本研究深入了解了辐射对 2-CA 的降解，并证明了辐射是处理含氯苯胺的化学废水的一种替代选择。
