期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 421, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2021.126806
关键词
Anoxic oxidation; Electron and atom exchange; Fe(IV) intermediate; Proton-coupled electron transfer; Stable Fe isotope
资金
- Strategic Priority Research Program of Chinese Academy of Sciences [XDB40020400]
- National Natural Science Foundations of China [42025705, U1701241, 41921004]
- West Light Foundation
- Frontier Science Research Programme of the Chinese Academy of Sciences [QYZDB-SSW-DQC046]
- National Key Research and Development Program of China [2020YFC180018]
- Science and Technology Planning Project of Guangdong Province, China [2019GDSYL-0401003, 2019GDA-SYL-0301002]
This study investigated the formation of oxidative intermediates during Fe(II)aq-induced recrystallization of goethite under anoxic conditions, confirming the generation of Fe(IV) originated from interfacial electron exchange between Fe(II)aq and Fe(III). This provides new insight into the anoxic oxidative transformation processes of matters in non-surface environments on earth.
Under anoxic conditions, aqueous Fe(II) (Fe(II)aq)-induced recrystallization of iron (oxyhydr)oxides changes the speciation and geochemical cycle of trace elements in environments. Oxidation of trace element, i.e., As(III), driven by Fe(II)aq-iron (oxyhydr)oxides interactions under anoxic condition was observed previously, but the oxidative species and involved mechanisms are remained unknown. In the present study, we explored the formed oxidative intermediates during Fe(II)aq-induced recrystallization of goethite under anoxic conditions. The methyl phenyl sulfoxide-based probe experiment suggested the featured oxidation by Fe(IV) species in Fe(II)aq-goethite system. Both the Mo center dot ssbauer spectra and X-ray absorption near edge structure spectroscopic evidenced the generation and quenching of Fe(IV) intermediate. It was proved that the interfacial electron exchange between Fe(II)aq and Fe(III) of goethite initiated the generation of Fe(IV). After transferring electrons to goethite, Fe(II)aq was transformed to labile Fe(III), which was then transformed to Fe(IV) via a proton-coupled electron transfer process. This highly reactive transient Fe(IV) could quickly react with reductive species, i.e. Fe(II) or As(III). Considering the ubiquitous occurrence of Fe(II)-iron (oxyhydr)oxides reactions under anoxic conditions, our findings are expected to provide new insight into the anoxic oxidative transformation processes of matters in non-surface environments on earth.
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