Zhou Huaxi, Xiao Dongxue
Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, P. R. China.
ACS Omega. 2022 Feb 23;7(9):7769-7776. doi: 10.1021/acsomega.1c06616. eCollection 2022 Mar 8.
The solar/chlorine system has been proposed as a novel advanced oxidation process (AOP) for efficient pollutant degradation and water disinfection by producing a series of reactive species including hydroxyl radicals (HO), chlorine radicals (Cl), and so forth. In this study, the role of natural organic matter (NOM) in the photolysis of free available chlorine (FAC) and the formation of HO and Cl in the solar/chlorine system was investigated employing nitrobenzene and benzoic acid as selective chemical probes. The decay rate of FAC was significantly accelerated in the presence of NOM at pH 5.5 under simulated solar irradiation, likely due to the photoreaction between FAC and the photoexcited NOM. The decay rate of FAC increased upon increasing the electron-donating capacity of NOM, which indicated that phenolic components play a significant role in the photodegradation of FAC. This acceleration mechanism was further verified using 4-nitrophenol as a model phenolic compound. NOM promoted Cl formation and quenched HO in the solar/chlorine system. The proposed reaction mechanism included the reaction of excited singlet phenolic compounds in NOM with FAC, which yielded Cl. This study provides a useful insight into future applications for using the solar/chlorine system as a novel AOP for wastewater treatment or disinfection.
太阳能/氯系统已被提议作为一种新型高级氧化工艺（AOP），通过产生一系列活性物种，包括羟基自由基（HO）、氯自由基（Cl）等，来实现高效的污染物降解和水消毒。在本研究中，以硝基苯和苯甲酸作为选择性化学探针，研究了天然有机物（NOM）在太阳能/氯系统中对游离有效氯（FAC）光解以及HO和Cl形成的作用。在模拟太阳辐射下，pH为5.5时，NOM的存在显著加速了FAC的衰减速率，这可能是由于FAC与光激发的NOM之间的光化学反应。随着NOM供电子能力的增加，FAC的衰减速率增大，这表明酚类成分在FAC的光降解中起重要作用。使用4-硝基苯酚作为模型酚类化合物进一步验证了这种加速机制。NOM促进了太阳能/氯系统中Cl的形成并淬灭了HO。所提出的反应机制包括NOM中激发的单线态酚类化合物与FAC反应生成Cl。本研究为将太阳能/氯系统作为一种新型AOP用于废水处理或消毒的未来应用提供了有益的见解。
