Journal
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume 52, Issue 15, Pages 8548-8557Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.7b06279
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Funding
- National Key Basic Research Program of China [2017YFA0207001]
- Natural Science Foundation of Jiangsu Province of China [BK20170050]
- National Natural Science Foundation of China [41671478, 41773125]
- Research Instrument Development Program of the Chinese Academy of Sciences [YZ201638]
- 135 Research Program of the Chinese Academy of Sciences
- Youth Innovation Promotion Association of CAS [2014270]
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Despite that persulfate radical (S2O8 center dot-) is an important radical species formed from the persulfate (PS) activation process, its reactivity toward contaminant degradation has rarely been explored. In this study, we found that S2O8 center dot- efficiently degrades the contaminant hexachloroethane (HCA) under anaerobic conditions, whereas HCA degradation is negligible in the presence of oxygen. We observed dechlorination products such as pentachloroethane, tetrachloroethylene, and Cl- during HCA degradation, which suggest that HCA degradation is mainly a reductive process under anaerobic conditions. Using free radical quenching and electron paramagnetic resonance (EPR) experiments, we confirmed that S2O8 center dot- forms from the reaction between sulfate radical (SO4 center dot-) and S2O82-, which are the dominant reactive species in HCA degradation. Density functional theory (DFT) calculations were used to elucidate the pathways of HCA degradation and S2O8 center dot- radical decomposition. Further investigation showed that S2O8 center dot- can efficiently degrade HCA and DDTs in soil via reduction during the thermal activation of PS under anaerobic conditions. The finding of this study provide a novel strategy for the reductive degradation of contaminant when PS-based in situ chemical oxidation used in the remediation of soil and groundwater, particularly those contaminated with highly halogenated compounds.
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