Enhanced effects of reducing agent on oxalate chelated Fe(II) catalyzed percarbonate system for benzene degradation

Xiaori Fu,Wupeng Yan,Peng Wei,Wei Zhang,Shuguang Lyu,Xinyan Wei

doi:10.2166/ws.2021.278

Xiaori Fu, Wupeng Yan + Show 4 more

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https://doi.org/10.2166/ws.2021.278

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Abstract

Abstract The addition of hydroxylamine hydrochloride (HAH), ascorbic acid (ASC), sodium ascorbate (SAS) to the OA-Fe(II)/SPC system could promote the generation of HO• by accelerating Fe(II)/Fe(III) recycles and H2O2 decomposition. The enhancement of HAH on HO• generation surpasses ASC and SAS in the OA-Fe(II)/SPC system. The generation of O2•− was also enhanced by HAH, ASC and SAS, and more significant promotion of O2•− generation was observed with ASC and SAS addition. More effective benzene removal was achieved in an OA-Fe(II)/SPC system with suitable HAH, ASC and SAS addition, compared to the parent system. Excessive HAH, ASC or SAS had a negative effect on benzene removal. Results of scavenger tests showed that HO• is indeed the dominant free radical for benzene removal in every system, but the addition of HAH, ASC and SAS increased the contribution of O2•− to benzene degradation. HAH, ASC and SAS enhanced OA-Fe(II)/SPC systems could be well utilized to acidic and neutral conditions, while HCO3−, high concentration of HA and alkaline conditions were not favorable to benzene removal. Moreover, the addition of HAH, ASC and SAS are conducive to benzene removal in actual groundwater, and HAH was the optimal reducing agent for the enhancement of the OA-Fe(II)/SPC system.

Highlights

Benzene, a toxic and hazardous compound of the BTEX family, has been listed as a USEPA priority pollutant and its maximum contaminant level was limited at 5 μg LÀ1 under the Safe Drinking Water Act (ATSDR 2004; USEPA 2009)
Effects of reducing agent on the production of free radicals Based on our previous work, both HO and O2À exists in the oxalic acid (OA)-Fe(II)/SPC system (Fu et al 2016)
Identical initial concentrations of reducing agents (RA), Fe(II), OA, and NB were set at 1 mM, and 2 mM of SPC and 0.05 mM of carbon tetrachloride (CT) were applied in the probe test. 3.1.1

Summary

Introduction

A toxic and hazardous compound of the BTEX family, has been listed as a USEPA priority pollutant and its maximum contaminant level was limited at 5 μg LÀ1 under the Safe Drinking Water Act (ATSDR 2004; USEPA 2009) This noxious compound can frequently be detected in contaminated groundwater and soils, and behaves as a significant menace to human health owing to its neurological damage and high carcinogenicity (Fu et al 2015). In situ chemical oxidation (ISCO) has been regarded as one of prominent and well-known technologies for contaminated groundwater and soils remediation because of its high cleanup efficiency Several oxidants, such as Fenton’s reagent (Ojinnaka et al 2012), persulfate (Petri 2010), peroxymonosulfate (Ahn et al 2016), permanganate (Mahmoodlu et al 2014), ozone (Hu & Xia 2017), and percarbonate (Fu et al 2016; Zang et al 2017) have been applied in the ISCO process.

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