Du Penghui, Liu Wen, Zhang Qiang, Zhang Peng, He Chen, Shi Quan, Huang Ching-Hua, Wang Junjian
Guangdong Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Science and Engineering, Peking University, Beijing 100871, China.
Water Res. 2023 Apr 1;232:119676. doi: 10.1016/j.watres.2023.119676. Epub 2023 Jan 28.
Peracetic acid combined ultraviolet (UV/PAA) process has garnered growing attention as a promising advanced oxidation process (AOP) for wastewater treatment, but the corresponding transformation of ubiquitous dissolved organic matter (DOM) under this AOP remains unknown. This study systematically investigated the changes in characteristics and composition of DOM under UV/PAA, as well as the underlying mechanisms by multiple spectroscopic analyses and Fourier transform ion cyclotron resonance mass spectrometry. UV/PAA treatment dramatically decreased aromaticity, apparent molecular weight, and fluorescent abundance of DOM with the production of more oxidized and saturated compounds. The reactive species (i.e., OH and CHC(O)O/CHC(O)OO) in UV/PAA contributed primarily to DOM changes but showed different reaction selectivity and mechanisms. OH reacts with DOM components and mainly yields oxygenation products via a radical addition pathway. Comparatively, the electron transfer route is more likely to occur in CHC(O)O/CHC(O)OO-induced DOM transformation. Aside from oxygenation products, electron transfer could exclusively generate decarboxylation products and distinguishes CHC(O)O/CHC(O)OO-based AOPs from OH-based AOPs. These findings significantly improve knowledge of DOM alterations under UV/PAA AOP at both the bulk and molecular levels.
过氧乙酸联合紫外线（UV/PAA）工艺作为一种有前景的高级氧化工艺（AOP）用于废水处理已受到越来越多的关注，但在该AOP作用下普遍存在的溶解有机物（DOM）的相应转化情况仍不清楚。本研究通过多种光谱分析和傅里叶变换离子回旋共振质谱系统地研究了UV/PAA作用下DOM的特性和组成变化以及潜在机制。UV/PAA处理显著降低了DOM的芳香性、表观分子量和荧光丰度，并生成了更多氧化和饱和的化合物。UV/PAA中的活性物种（即·OH和CHC(O)O/CHC(O)OO）对DOM变化起主要作用，但表现出不同的反应选择性和机制。·OH与DOM成分反应，主要通过自由基加成途径生成氧化产物。相比之下，电子转移途径更可能发生在CHC(O)O/CHC(O)OO诱导的DOM转化中。除了氧化产物外，电子转移还能专门生成脱羧产物，并将基于CHC(O)O/CHC(O)OO的AOP与基于·OH的AOP区分开来。这些发现显著提高了在整体和分子水平上对UV/PAA AOP作用下DOM变化的认识。
