Sorption of Se species on mineral surfaces, part I: Batch sorption and multi-site modelling. (August 2018)

• Record Type: Journal Article
• Authors: Li, Xiaodong; Puhakka, Eini; Ikonen, Jussi; Söderlund, Mervi; Lindberg, Antero; Holgersson, Stellan; Martin, Andrew; Siitari-Kauppi, Marja
• Is Part Of: Applied geochemistry. Volume 95(2018)
• Page Start: 147
• Page End: 157
• Publication Date: 2018-08
• Subjects: Selenium -- Sorption -- Crystalline rock -- Minerals -- Surface complexation modelling; Environmental geochemistry -- Periodicals; Water chemistry -- Periodicals; Geochemistry -- Social aspects -- Periodicals; Geochemistry -- Periodicals; 551.9
• DOI: 10.1016/j.apgeochem.2018.05.024
• Languages: English
• ISSNs: 0883-2927

Abstract

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 1.66 × 10 −10 M to 1 × 10 −3 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 (<10 −7 M) stabilizing between 0.0595 ± 0.0097 m 3 /Kg and 0.0713 ± 0.0164 m 3 /Kg. The Kd value of Se(IV) on K-feldspar was the second largest (0.0154 ± 0.0019 m 3 /Kg in 10 −9 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 0.0078 ± 0.0010 m 3 /Kg for Grimsel granodiorite and 0.0085 ± 0.0016 m 3 /Kg for plagioclase, when Se(IV) concentration was 10 −9 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 HSeO3 − and SeO3 2− . 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. Highlights: Kd values of Se(IV) sorption on Grimsel granodiorite and main minerals. Relationship between Kd values and SSA. Surface complexation modelling of Se(IV) on biotite. Sorption site density calculated by molecular modelling.