Overlooked enhancement of chloride ion on the transformation of reactive species in peroxymonosulfate/Fe(II)/NH 2 OH system

Though hydroxylamine (NH OH) is effective for accelerating pollutants degradation in Fenton and Fenton-like systems, the effect of anions simultaneously introduced by the hydroxylamine salts have always been ignored. Herein, effect of two commonly used hydroxylamine salts, hydroxylamine hydrochlorid...

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Bibliographic Details
Published in:Water research (Oxford) 2021-05, Vol.195, p.116973
Main Authors: Li, Zhuo-Yu, Wang, Lu, Liu, Yu-Lei, He, Pei-Nan, Zhang, Xin, Chen, Jia, Gu, Hai-Teng, Zhang, Hao-Chen, Ma, Jun
Format: Article
Language:English
Subjects:
Chlorides
Ferrous Compounds
Iron
Oxidation-Reduction
Peroxides
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Summary:Though hydroxylamine (NH OH) is effective for accelerating pollutants degradation in Fenton and Fenton-like systems, the effect of anions simultaneously introduced by the hydroxylamine salts have always been ignored. Herein, effect of two commonly used hydroxylamine salts, hydroxylamine hydrochloride (NH OH·HCl) and hydroxylamine sulfate [(NH OH) ·H SO ], for the degradation of dimethyl phthalate (DMP) in peroxymonosulfate (PMS)/Fe(II) system was comparatively investigated. Degradation efficiency of DMP with NH OH·HCl was 1.6 times of that with same dosages of (NH OH) ·H SO . SO , Fe(IV) and ·OH formed in the PMS/Fe(II)/NH OH system, but ·OH was the major species for DMP degradation. Addition of Cl significantly improved the production of ·OH and Cl·, and the exposure dose of ·OH (CT ) was more than 10 times that of CT as the concentration of Cl increased to 1 mM. Calculations based on branching ratios of Cl· and ·OH indicated that the reactions of Cl with SO and Cl· with H O were not the only production sources of ·OH in the system. Further experiments with methyl phenyl sulfoxide (PMSO) as the probe indicated that Cl would facilitate the shift of reactive species from Fe(IV) to radicals (SO or ·OH) in the system. Both hydroxylation and nitration intermediate products were detected in the oxidation of DMP. Cl promoted the formation of hydroxylation intermediates and reduced the formation of nitration intermediates. This study revealed for the first time that Cl could shift reactive species from Fe(IV) to radicals in PMS/Fe(II) system, raising attention to the influence of the coexisting anions (especially Cl ) for pollutants oxidation in iron-related oxidation processes.
ISSN:1879-2448