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Article

Unusual Catalytic Effect of Fe3+ on 2,4-dichlorophenoxyacetic Acid Degradation by Radio Frequency Discharge in Aqueous Solution

College of Environmental Science & Engineering, Dalian Maritime University, Dalian 116026, China
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Academic Editors: Gassan Hodaifa, Antonio Zuorro, Joaquín R. Dominguez, Juan García Rodríguez, José A. Peres and Zacharias Frontistis
Water 2022, 14(11), 1719; https://doi.org/10.3390/w14111719
Received: 2 May 2022 / Revised: 20 May 2022 / Accepted: 23 May 2022 / Published: 27 May 2022
(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)
2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide for controlling broad-leaved weeds. The development of an efficient process for treating the refractory 2,4-D wastewater is necessary. In this study, liquid-phase degradation of 2,4-D induced by radio frequency discharge (RFD) was studied. Experimental results showed that the degradation was more effective in acidic than in neutral or alkaline solutions. During the degradation, a large amount of hydrogen peroxide (H2O2, 1.2 mM/min, almost equal to that without 2,4-D) was simultaneously produced, and catalytic effects of both ferric (Fe3+) and ferrous (Fe2+) ions on the degradation were examined and compared. It was found that 2,4-D degraded more rapidly in the case of Fe3+ than the that of Fe2+. Such a scenario is explained that Fe3+ was successively reduced to Fe2+ by the atomic hydrogen (•H) and •OH-adducts of 2,4-D resulting from RFD, which in turn catalyzed the H2O2 to form more •OH radicals through Fenton’s reaction, indicating that Fe3+ not only accelerates the degradation rate but also increases the amount of •OH available for 2,4-D degradation by suppressing the back reaction between the •H and •OH. 2,4-dichlorophenol, 4,6-dichlororesorcinol, 2-hydroxy-4-chloro- and 2-chloro-4-hydroxy- phenoxyacetic acids, hydroxylated 2,4-Ds, and carboxylic acids (glycolic, formic and oxalic) were identified as the byproducts. Energy yields of RFD have been compared with those of other nonthermal plasma processes. View Full-Text
Keywords: aqueous solution; radio frequency discharge; 2,4-D; degradation; Fenton aqueous solution; radio frequency discharge; 2,4-D; degradation; Fenton
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MDPI and ACS Style

Liu, Y.; Sun, B. Unusual Catalytic Effect of Fe3+ on 2,4-dichlorophenoxyacetic Acid Degradation by Radio Frequency Discharge in Aqueous Solution. Water 2022, 14, 1719. https://doi.org/10.3390/w14111719

AMA Style

Liu Y, Sun B. Unusual Catalytic Effect of Fe3+ on 2,4-dichlorophenoxyacetic Acid Degradation by Radio Frequency Discharge in Aqueous Solution. Water. 2022; 14(11):1719. https://doi.org/10.3390/w14111719

Chicago/Turabian Style

Liu, Yongjun, and Bing Sun. 2022. "Unusual Catalytic Effect of Fe3+ on 2,4-dichlorophenoxyacetic Acid Degradation by Radio Frequency Discharge in Aqueous Solution" Water 14, no. 11: 1719. https://doi.org/10.3390/w14111719

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