Mechanism of heterogeneous activation of persulfate with FeOCl under visible light irradiation
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ARTICLE Mechanism of heterogeneous activation of persulfate with FeOCl under visible light irradiation Mengdie Chen School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, People’s Republic of China
Haiming Xu Engineering Research Center Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan 430200, People’s Republic of China
Xiaofang Zhang School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, People’s Republic of China
Dongya Lia) School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, People’s Republic of China; and Engineering Research Center Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan 430200, People’s Republic of China
Dongsheng Xiab) School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, People’s Republic of China (Received 26 March 2018; accepted 22 June 2018)
Activation of persulfate (PS) by ultraviolet light or transition metal catalysts has been extensively studied. However, little is known about the activation of PS by iron oxychloride (FeOCl) in the presence of visible light irradiation. Herein, the catalytic activity of FeOCl was developed for oxidative degradation of rhodamine B (RhB) with the FeOCl/PS/Vis process. The characterization of FeOCl for reaction kinetics, degradation mechanism, and catalyst stability was investigated. It is found that the redox cycle of iron species and photoinduced electrons formed on the FeOCl catalyst surface can effectively activate PS, to generate radicals. Based on quenching experiments and electron paramagnetic resonance, the photogenerated holes (h1) and sulfate radicals (SO4d) are the predominant reactive oxidants for RhB decolorization, while superoxide radicals (dO2) and hydroxyl radicals (dOH) are also involved. Moreover, FeOCl shows good catalytic performance in a wide range of pH values (pH 5 3–10) and excellent reusability and stability, as well.
I. INTRODUCTION
Recently, sulfate radical (SO4d)-based advanced oxidation processes (SR-AOPs) have attracted more and more attention because SO4d has a higher redox potential (E0(SO4d/SO42) 5 2.5–3.1 VNHE) than hydroxyl radicals (dOH, E0(dOH/H2O) 5 2.2–2.7 VNHE) and can react with most organic contaminants.1 Moreover, SO4d can sustain high activity in a neutral or basic aqueous medium and shows better adjustability to a broad pH range, compared with dOH.2 Most commonly, SO4d can be generated from persulfate (PS, S2O82) activation. PS is relatively cheap, highly soluble in water, and stable at ambient temperatures.3 Production uses of SO4d in the current literature include transition metals,4 photolysis,5 pyrolysis,6 and microwave-assisted processes.7 Among those, the transition metals that have been a research hotspot, such as Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2018.246 J. Mater. Res., 2018
Fe21, Co21, Mn21, Ru31, and Ag1,8 can induce PS to produce SO4d in homogeneous
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