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Competing Sorption of Se(IV) and Se(VI) on Schwertmannite

Title data

Marouane, Bouchra ; Chen, Ning ; Obst, Martin ; Peiffer, Stefan:
Competing Sorption of Se(IV) and Se(VI) on Schwertmannite.
In: Minerals. Vol. 11 (15 July 2021) Issue 7 . - pp. 1-14.
ISSN 2075-163X
DOI: https://doi.org/10.3390/min11070764

Official URL: Volltext

Project information

Project financing: European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 706140
DFG-PE 438/24-1

Abstract in another language

Schwertmannite (SHM) is a naturally occurring mineral that has been shown to effectively scavenge oxyanions from contaminated water. In this study, Fourier-transform infrared spectroscopy and X-ray absorption spectroscopy techniques in combination with wet-chemical techniques were used to study the competitive sorption of Se(IV) and Se(VI) at pH 3. The experiments were conducted with three types of schwertmannite obtained from oxidative synthesis, biogenic synthesis and high- pressure compaction at different initial Se concentrations and mixing ratios for 48 h and 56 days, respectively. A threshold value for the uptake mechanisms was identified, which reflects the amount of easily exchangeable sulphate (~0.5 mmol/g). At adsorbate concentrations below this threshold, an inner-sphere corner-sharing bidentate binuclear complex forms upon exchange with sulphate. At higher concentrations, both oxyanions become bound to SHM through co-occurrence of mainly inner-sphere and partly outer-sphere corner-sharing bidentate binuclear complexes with Fe(III) containing surface sites. Single species experiments clearly indicate a higher affinity of SHM for Se(IV). However, in mixed species experiments, competitive sorption occurs with equal or even preferential uptake of Se(VI) at concentrations much lower than the threshold value, presumably due to geometrical similarity between selenate and sulphate, and increasing preference for Se(IV) at high Se concentrations.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Schwertmannite; Selenite; Selenate; Adsorption mechanism; XAS
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Hydrology
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Hydrology > Chair Hydrology - Univ.-Prof. Dr. Stefan Peiffer
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Heisenberg Professorship - Experimental Biogeochemistry > Heisenberg Professorship - Experimental Biogeochemistry - Univ.-Prof. Dr. Martin Obst
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Heisenberg Professorship - Experimental Biogeochemistry
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 550 Earth sciences, geology
Date Deposited: 27 Jul 2021 06:45
Last Modified: 27 Jul 2021 06:45
URI: https://eref.uni-bayreuth.de/id/eprint/66695