Molecular Level Insights into HO• and Cl2•−-Mediated Transformation of Dissolved Organic Matter in Landfill Leachate Concentrates during the Fenton Process
Molecular Level Insights into HO• and Cl2•−-Mediated Transformation of Dissolved Organic Matter in Landfill Leachate Concentrates during the Fenton Process
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DOI：
10.1016/j.cej.2022.137062
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发表时间：
2022-05
影响因子：
15.1
通讯作者：
Quanfa Zhong;Zhongyuan Zhang;Qinglong Fu;Jingfeng Yu;X. Liao;J. Zhao;Di He
中科院分区：
文献类型：
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作者：
Quanfa Zhong;Zhongyuan Zhang;Qinglong Fu;Jingfeng Yu;X. Liao;J. Zhao;Di He
当采用高级氧化工艺（AOPs）处理高盐度废水时，Cl 2·−可能是主要的自由基物种。在这项研究中，在芬顿处理两个垃圾渗滤液浓缩液具有显着不同的Cl-浓度（XPNF：1406 mg/L; SNNF：8036 mg/L）的稳态浓度的HO·，Cl·和Cl 2·−测定。基于自由基物种的稳态浓度和溶解有机物（DOM）的二级速率常数，在XPNF中HO·占DOM转化的76.2%，而在SNNF中Cl 2·−占96.5%。然后通过高分辨质谱技术，对HO·和Cl 2·−主导的DOM转化进行了全面的比较，研究了HO·和Cl 2·−与DOM在分子水平上的反应性。结果表明，HO·优先去除低氧化度（O/C < 0.5）的化合物，HO·对高饱和度（H/C > 1.5）的化合物的反应活性高于Cl 2·−。相比之下，Cl 2·−对饱和度较低（H/C < 1.5）的化合物反应性更强，且Cl 2·−与DOM的反应对DOM氧化程度的依赖性较小。此外，HO·优先与低N含量的CHON化合物反应，而Cl 2·−与高N含量的CHON化合物相比，HO·更易反应。据我们所知，这是第一个在分子水平上区分HO·和Cl 2·−对DOM反应性差异的研究。
Cl2•−can be the dominant radical species when high salinity wastewater is treated by advanced oxidation processes (AOPs). In this study, the steady-state concentrations of HO•, Cl•and Cl2•−were determined during the Fenton treatment of two landfill leachate concentrates with significantly different Cl−concentrations (XPNF: 1406 mg/L; SNNF: 8036 mg/L). Based on the steady-state concentrations of the radical species and measured second-order rate constants with dissolved organic matters (DOM), HO•accounted for 76.2% of DOM transformation in XPNF, while Cl2•−accounted for 96.5% in SNNF. The DOM transformation dominated by HO•or Cl2•−was then thoroughly compared to investigate the reactivities of HO•and Cl2•−with DOM at molecular level using high-resolution mass spectrometry. The results showed that formulas with low oxidation degree (O/C < 0.5) were preferentially removed by HO•and HO•was more reactive towards compounds with high saturation degree (H/C > 1.5) compared with Cl2•−. In contrast, Cl2•−was more reactive to the compounds with lower saturation level (H/C < 1.5) and the reaction of Cl2•−with DOM was less dependent on DOM oxidation degree. In addition, HO•preferentially reacted with the CHON compounds with low N content, while Cl2•−was more reactive to CHON compounds with higher N content compared with HO•. To our knowledge, this is the first study to distinguish the difference in the reactivity of HO•and Cl2•−towards DOM at molecular level.