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New Insight into the Natural Detoxification of Cr(VI) in Fe-Rich Surface Soil: Crucial Role of Photogenerated Silicate-Bound Fe(II)
ID：127 View Protection：ATTENDEE Updated Time：2025-05-21 16:49:54 Hits：161 Oral Presentation

Start Time：Pending（Asia/Shanghai）

Duration：Pending

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Abstract
Photoexcitation of natural semiconductor Fe(III) minerals has been proven to generate Fe(II), but the photogeneration of Fe(II) in Fe-rich surface soil as well as its role in the redox biogeochemistry of Cr(VI) remains poorly understood. In this work, we confirmed the generation of Fe(II) in soil by solar irradiation and proposed a new mechanism for the natural reductive detoxification of Cr(VI) to Cr(III) in surface soil. The kinetic results showed that solar irradiation promoted the reduction of Cr(VI) in Fe-rich soils, while a negligible Cr(VI) reduction was observed in the dark. Fe(II), mainly in the form of silicate-bound Fe(II), was generated under solar irradiation and responsible for the reduction of Cr(VI) in soils, which was evidenced by sequential extraction, transmission electron microscopy with electron energy loss spectroscopy, and electron transfer calculation. Photogenerated silicate-bound Fe(II) resulted from the massive clay–iron (hydr)oxide associations, consisting of iron (hydr)oxides (e.g., hematite and goethite) and kaolinite. These associations could generate Fe(II) under solar irradiation either via intrinsic excitation to produce photoelectrons or via the ligand-to-metal charge transfer process after the formation of clay–iron (hydr)oxide–organic matter complexes, which was proven by photoluminescence spectroscopy and X-ray photoelectron spectroscopy. These findings highlight the important role of photogenerated Fe(II) in Cr(VI) reduction in surface soil, which advances a fundamental understanding of the natural detoxification of Cr(VI) as well as the redox biogeochemistry of Cr(VI) in soil.
Keywords
Cr(VI) biogeochemistry,clay-iron (hydr)oxide associations,photogenerated Fe(II),surface soil,solar irradiation
Speaker
zehong zhang
Ph.D candidate Shanghai Jiao Tong University

Submission Author
zehong zhang Shanghai Jiao Tong University
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Important Date

  • Conference Date

    Jun 10

    2025

    to

    Jun 13

    2025

  • Apr 15 2025

    Draft paper submission deadline

Sponsored By
National Natural Science Foundation of China
Geobiology Society
National Committee of Stratigraphy of China
Ministry of Science and Technology
Geological Society of China
Paleontological Society of China
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (CAS)
Institute of Vertebrate Paleontology and Paleoanthropology, CAS
International Commission on Stratigraphy
International Paleontological Association
Organized By
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (CUG, Wuhan)
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