Effect of chelating agents on Reactive Green 19 decolorization through Fe0-activated persulfate oxidation process

•Oxidation of RG19 by PS/Fe0 process was retarded by chelating agents.•Influence of chelating agents on RG19 decolorization: citrate > EDTA > oxalate.•Influence of reaction parameters on RG19 degradation was evaluated.•Presence of sodium EDTA had no influence on by-products of RG19.

The effect of chelating agents on the decolorization of Reactive Green 19 (RG19) through Fe0 activated persulfate (PS/Fe0) process was investigated. Though other previous studies reported that chelating agent can enhance the degradation of organic contaminant in Fenton-like system, our finding showed that the presence of chelating agents would chelate free Fe2+ and minimize free Fe2+ concentration, which resulted in the retardation of RG19 decolorization. RG19 decolorization decreased to 7%, 21%, and 15% in the presence of sodium citrate, sodium EDTA, and sodium oxalate, compared with control test (without chelating agent, 99%) within 10 min. The degradation efficiencies decreased with increasing chelating agent concentrations because of complex formation with Fe2+. Higher PS concentration, Fe0 dosage, and temperature had an obvious enhancement for RG19 decolorization efficiency. Elucidation of RG19 containing sodium EDTA degradation pathways indicated that PS/Fe0 process could degrade RG19 to carboxylic acids and inorganic salts efficiently. The presence of sodium EDTA had no influence on by-products, and EDTA just played a chelating agent function for chelating Fe ions.

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