Sorption in an ammonioalunite-ammoniojarosite solid solution: results for the 1, 2, 4, 7, 11, 12 and 13 group elements and LREEs

Abstract

This paper collates selected analytical results from a 1-year sorption experiments conducted on natural samples of an ammonioalunite-ammoniojarosite solid solution (AAJ) of known initial composition. These include Electron Microprobe (EPMA)  and Powder X-Ray Diffraction (PXRD) results for baths subjected to Li₂SO_4·H₂O, KI, Rb₂CO₃ (0.33–0.62 wt.% Rb₂O in the AAJ, CsCl (0.24–1.07 wt.% Cs₂O), Ca(OH)₂ (ettringite formation), Sr(NO₃)₂ (0.31–10.25 wt.% SrO), ZrO(NO₃)₂·2H₂O, MnSO₄·H₂O, CuSO₄·5H₂O (up to 1.05 wt.% CuO), ZnCl₂, Ga(NO₃)₃·9H₂O (5.86-21.44 wt.% Ga₂O₃), ZrCl₄ (up to 17.56 wt.% ZrO₂ in AAJ, i.e., up to 0.27 apfu Zr, InCl₃ (0.85–17.04 wt.% In₂O₃, i.e., possibly up to 0.42 apfu), KH₂AsO₄ (up to 45.93 wt.%  As₂O₅,  recast to 1.64 apfu As), K₂SeO₃ (up to 44.86 wt.%  SeO₂, recast to 1.55 apfu Se), LaCl₃·7H₂O (0.17–0.22 wt.% La₂O₃), CeCl₃·7H₂O (0.38–1.74 wt.% Ce₂O₃), and PrCl₃·6H­₂O (1.66–4.10 wt.% Pr₂O₃). Zn, Mn, and I only rarely show accumulation. (NH₄)Fe₃(AsO₄)₂[(OH)₄(H₂O)₂] and (NH₄)Fe₃[(AsO₄)(SO₄)][(OH)₅(H₂O)] are occasionally the dominant hypothetical end-members in the As experiment. In the KI case the resulting material is 1.6 times more enriched in K than the base used. Special attention is paid to Zr, with PXRD and EPMA results not ideally coincident with a trial Scanning Electron Microscopy-Electron Backscatter Diffraction study suggesting deposition of tetragonal ZrSiO₄ (synthetic zircon).