Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China; CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science & Technology of China, Hefei, 230026, China.
CAS Key Laboratory of Urban Pollutant Conversion, Department of Applied Chemistry, University of Science & Technology of China, Hefei, 230026, China.
J Hazard Mater. 2020 Jan 15;382:121090. doi: 10.1016/j.jhazmat.2019.121090. Epub 2019 Aug 24.
Fenton reaction is widely used for hazardous pollutant degradation. Reducing agents (RAs) have been proven to be efficient in promoting the generation of HO• in Fenton reaction by accelerating the redox cycle of Fe/Fe. However, the roles of different RAs in Fenton reaction remain unrevealed. In this work, the catalytic activity of three RAs, i.e., hydroxylamine (NHOH), ascorbic acid (AA) and cysteine (Cys), on the degradation of benzoic acid (BA) and the hydroxyl radical formation in the Fenton-RAs system were investigated. Results show the catalytic performance of RAs in BA degradation by Fenton reaction followed an order of NHOH > AA > Cys. Compared with the conventional Fenton system, the effective pH range in the Fenton-NHOH system extended from 3.0 to 5.0, while the optimal pH in the Fenton-AA and Fenton-Cys systems ranged from 3.0 to 4.0. The Fenton-AA system exhibited a two-stage reaction toward BA degradation, which was different from the Fenton-NHOH and Fenton-Cys systems. Furthermore, the dosing manner of AA was found to be a key factor governing its role in the Fenton-AA system. This observation suggests the different mechanisms behind the enhancement of the three RAs in Fenton system. Different from NHOH and Cys, AA would inhibit the generation of HO•, especially at the fast stage of degradation process, where Fe has not accumulated yet. In addition, the economic analysis using the electrical energy per order indicates Fenton-NHOH system was economically feasible with the lowest energy input, compared to Fenton-AA and Fenton-Cys systems. These results are useful to better understand the roles of RAs in Fenton system, and also provide guidance about the selection and dosing manner of suitable RAs in the advanced oxidation processes.
芬顿反应被广泛用于降解危险污染物。还原剂 (RAs) 已被证明通过加速 Fe/Fe 的氧化还原循环，有效地促进了 Fenton 反应中 HO•的生成。然而，不同 RAs 在 Fenton 反应中的作用仍未被揭示。在这项工作中，研究了三种还原剂，即羟胺 (NHOH)、抗坏血酸 (AA) 和半胱氨酸 (Cys) 在 Fenton-RA 体系中对苯甲酸 (BA) 降解和羟基自由基生成的催化活性。结果表明，RA 在 Fenton 反应中对 BA 降解的催化性能遵循 NHOH > AA > Cys 的顺序。与传统的芬顿体系相比，Fenton-NHOH 体系的有效 pH 范围从 3.0 扩展到 5.0，而 Fenton-AA 和 Fenton-Cys 体系的最佳 pH 范围从 3.0 到 4.0。Fenton-AA 体系对 BA 降解表现出两阶段反应，与 Fenton-NHOH 和 Fenton-Cys 体系不同。此外，发现 AA 的投加方式是控制其在 Fenton-AA 体系中作用的关键因素。这一观察结果表明了三种 RAs 在 Fenton 体系中增强作用的不同机制。与 NHOH 和 Cys 不同，AA 会抑制 HO•的生成，特别是在降解过程的快速阶段，此时 Fe 尚未积累。此外，使用单位能耗进行的经济分析表明，与 Fenton-AA 和 Fenton-Cys 体系相比，Fenton-NHOH 体系具有最低的能源输入，具有经济可行性。这些结果有助于更好地理解 RAs 在 Fenton 体系中的作用，并为在高级氧化过程中选择和投加合适的 RAs 提供指导。
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