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Antimonite complexation with thiol and carboxyl/phenol groups of peat organic matter

Title data

Besold, Johannes ; Kumar, Naresh ; Scheinost, Andreas C. ; Lezama-Pacheco, Juan ; Fendorf, Scott ; Planer-Friedrich, Britta:
Antimonite complexation with thiol and carboxyl/phenol groups of peat organic matter.
In: Environmental Science & Technology. Vol. 53 (2019) Issue 9 . - pp. 5005-5015.
ISSN 0013-936X
DOI: https://doi.org/10.1021/acs.est.9b00495

Abstract in another language

Peatlands and other wetlands with abundant natural organic matter (NOM) are important sinks for antimony (Sb). While formation of Sb(III) sulfide phases or Sb(III) binding to NOM are discussed to decrease Sb mobility, the exact binding mechanisms remain elusive. Here, we reacted increasing sulfide concentrations with purified model peat at pH 6, forming reduced organic sulfur species, and subsequently equilibrated the reaction products with 50 µM antimonite under anoxic conditions. Sulfur solid-phase speciation and the local binding environment of Sb were analyzed using X-ray absorption spectroscopy. We found that 85% of antimonite was sorbed by untreated peat. Sulfide-reacted peat increased sorption to 98%. Shell-by-shell fitting of Sb K-edge X-ray absorption fine structure spectra revealed Sb in untreated peat bound to carboxyl or phenol groups with average Sb-carbon distances of ~2.90 Å. With increasing content of reduced organic sulfur, Sb was progressively coordinated to S atoms at distances of ~2.45 Å and Sb-carbon distances of ~3.33 Å, suggesting increasing Sb-thiol binding. Iterative target factor analysis allowed exclusion of reduced inorganic Sb-sulfur phases with similar Sb-sulfur distances. In conclusion, even when free sulfide concentrations are too low for formation of Sb-sulfur precipitates, peat NOM can sequester Sb in anoxic, sulfur-enriched environments.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER150870
Institutions of the University: Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Environmental Geochemistry Group
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Environmental Geochemistry Group > Professor Environmental Geochemistry - Univ.-Prof. Dr. Britta Planer-Friedrich
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 23 Jan 2020 08:00
Last Modified: 23 Jan 2020 08:00
URI: https://eref.uni-bayreuth.de/id/eprint/53796