Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8863085 | Applied Geochemistry | 2018 | 41 Pages |
Abstract
The sorption behavior of Se(IV) on Grimsel granodiorite and its main minerals, plagioclase, K-feldspar, quartz and biotite, were investigated in Grimsel groundwater simulant in a large Se concentration range (from 1.66â¯Ãâ¯10â10â¯M to 1â¯Ãâ¯10â3â¯M). Experimental results show that the distribution coefficients (Kd values) of Se(IV) on the rock and mineral samples increased with the decreasing of Se(IV) concentration. The sorption of Se(IV) on biotite has the largest Kd value in low concentration area (<10â7â¯M) stabilizing between 0.0595â¯Â±â¯0.0097â¯m3/Kg and 0.0713â¯Â±â¯0.0164â¯m3/Kg. The Kd value of Se(IV) on K-feldspar was the second largest (0.0154â¯Â±â¯0.0019â¯m3/Kg in 10â9â¯M) while the sorption on quartz was negligible. The sorption behavior of Se(IV) on Grimsel granodiorite followed the same trend as plagioclase, the most abundant mineral in Grimsel granodiorite, with Kd values of 0.0078â¯Â±â¯0.0010â¯m3/Kg for Grimsel granodiorite and 0.0085â¯Â±â¯0.0016â¯m3/Kg for plagioclase, when Se(IV) concentration was 10â9 M. HPLC-ICP-MS results show that all the Se(IV) remained in +IV oxidation state after more than 1 month experimental time and speciation modelling proved that the main species in Grimsel groundwater simulant were HSeO3â and SeO32â. Multi-site surface complexation modelling was performed by PHREEQC with the help of molecular modelling techniques which was performed with the CASTEP code implemented into Materials Studio. The modelling results predict that there are three kinds of sorption sites on the surface of biotite mineral, with sorption site densities differing in three magnitudes.
Related Topics
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Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Xiaodong Li, Eini Puhakka, Jussi Ikonen, Mervi Söderlund, Antero Lindberg, Stellan Holgersson, Andrew Martin, Marja Siitari-Kauppi,