Mechanisms of Interaction between Persulfate and Soil Constituents: Activation, Free Radical Formation, Conversion, and Identification

Abstract

Persulfate-based in situ chemical oxidation (ISCO) for soil remediation has received great attention in recent years. However, the mechanisms of interaction between persulfate (PS) and soil constituents are not fully understood. In this study, PS decomposition, activation, free radical formation and conversion processes in 10 different soils were examined. The results showed that soil organic matter (SOM) was the dominant factor affecting PS decomposition in soil, but Fe/Mn-oxides were mainly responsible for PS decomposition when SOM was removed. Electron paramagnetic resonance (EPR) spectroscopy analysis showed that sulfate radicals (SO4 •–) and hydroxyl radicals (•OH) generated from PS decomposition subsequently react with SOM to produce alkyl-like radicals (R•), and this process is dependent on SOM content. R• and SO4 •–/•OH radicals predominated in soil with high and low SOM, respectively, and all three radicals coexist in soil with medium SOM. Chemical probe analysis further identified the types of radicals, and R• can reductively degrade hexachloroethane in high SOM soil, while SO4 •– and •OH oxidatively degrade phenol in low SOM soil. These findings provide valuable information for PS-ISCO, and new insight into the role of SOM in the remediation of contaminated soil.

Degradation of methylparaben by sonocatalysis using a Co–Fe magnetic carbon xerogel

“…4. The rational for this set of experiments has to do with the fact that SPS activation to generate extra sulfate and hydroxyl radicals can be implemented by both the carbocatalyst containing iron and cobalt [28][29][30][31] and the action of ultrasound [32]. Indeed, the catalyst seems to activate SPS, thus enhancing MP removal during the silent run; this is consistent with previous findings of our group concerning the removal of bisphenol A by the CX/CoFe-SPS system [20].…”

Synthesis and theoretical calculations of metal-antibiotic chelation with thiamphenicol:in vitroDNA and HSA binding, molecular docking, and cytotoxicity studies

“…Electron spin resonance (ESR), also known as electron paramagnetic resonance (EPR), is a powerful analytical tool that selectively detects species with unpaired electrons such as paramagnetic transition metal complexes like copper and iron complexes 32,33 and organic free radicals. [34][35][36][37] In addition to structural information, EPR spectra provide important information on the atoms that coordinate with the transition metal. [38][39][40] The solid sample spectrum of the Cu-TM compound obtained in X-band EPR spectroscopy at room temperature is shown in Fig.…”

Integration of microbial reductive dehalogenation with persulfate activation and oxidation (Bio-RD-PAO) for complete attenuation of organohalides

“…To enhance the microbial reductive dehalogenation efficiency, many biostimulation strategies have been devised and employed, including the addition of vegetable oils as slow-releasing organic carbons and electron donors to support organohalide respiration of OHRB (Herrero et al, 2019). These biostimulation materials are left or transferred into other organic matter as intermediates, which may consume sulfate radicals and decrease the efficiency of subsequent PAO in organohalide remediation (Ouyang et al, 2017;Fang et al, 2018). In addition, a variety of minerals, ions and organic matter in soil and subsurface environments also consume persulfate-derived sulfate radicals, which has been comprehensively reviewed by Lee and colleagues (Lee et al, 2020a).…”