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A Mechanistic Understanding of Hydrogen Peroxide Decomposition by Vanadium Minerals for Diethyl Phthalate Degradation

Fang, Guodong, Deng, Yamei, Huang, Min, Dionysiou, Dionysios D., Liu, Cun, Zhou, Dongmei
Environmental science & technology 2018 v.52 no.4 pp. 2178-2185
X-ray diffraction, X-ray photoelectron spectroscopy, aqueous solutions, diethyl phthalate, electron paramagnetic resonance spectroscopy, electron transfer, free radicals, hydrogen peroxide, hydroxyl radicals, minerals, oxidation, oxygen, pH, remediation, slurries, soil, vanadium
The interaction of naturally occurring minerals with H₂O₂ affects the remediation efficiency of polluted sites in in situ chemical oxidation (ISCO) treatments. However, interactions between vanadium(V) minerals and H₂O₂ have rarely been explored. In this study, H₂O₂ decomposition by various vanadium-containing minerals including V(III), V(IV), and V(V) oxides was examined, and the mechanism of hydroxyl radical (•OH) generation for contaminant degradation was studied. Vanadium minerals were found to catalyze H₂O₂ decomposition efficiently to produce •OH for diethyl phthalate (DEP) degradation in both aqueous solutions with a wide pH range and in soil slurry. Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) analyses, and free radical quenching studies suggested that •OH was produced via single electron transfer from V(III)/V(IV) to H₂O₂ followed a Fenton-like pathway on the surface of V₂O₃ and VO₂ particles, whereas the oxygen vacancy (OV) was mainly responsible for •OH formation on the surface of V₂O₅ particles. This study provides new insight into the mechanism of interactions between vanadium minerals and H₂O₂ during H₂O₂-based ISCO.