X-ray absorption spectroscopy study of solvation and ion-pairing in aqueous gallium bromide solutions at supercritical conditions

Publication

Reference: Da Silva Cécile, Proux Olivier, Hazemann Jean-Louis, James-Smith Julianne, Testemale Denis, Yamaguchi Toshio (2009). X-ray absorption spectroscopy study of solvation and ion-pairing in aqueous gallium bromide solutions at supercritical conditions. J. Mol. Liq., 147, 83 - 95.

Names

Title: X-ray absorption spectroscopy study of solvation and ion-pairing in aqueous gallium bromide solutions at supercritical conditions
Abstract: X-ray absorption spectroscopy measurements have been performed both at the Ga and Br K-edges on aqueous GaBr 3 solutions. The isobaric experiments have been recorded at 30 MPa from ambient temperature to 670 K for two GaBr 3 concentrations (0.017 and 0.17 mol/dm 3 ). At room temperature, Ga 3+ and Br − ions are fully solvated, surrounded by water O atoms at 1.97 Å (Ga–O) and 3.37 Å (Br–O). When the temperature is elevated, Ga 3+ cations precipitate as gallium oxy-hydroxide colloids while Br − anions remain solvated. With a further increase in temperature, the gallium solid precipitates remarkably re-dissolved (25% and 50% − n (n = 2, 3 or 4) for 0.017 and 0.17 mol/dm 3 respectively), due to the formation of [GaBr n (H 2 O) 4 − n ] 3 (aq) tetrahedral complexes.
Keywords: Gallium bromide solution, Ion solvation, Ion pairing, Supercritical fluids, XANES, x-ray absorption spectroscopy
Content: sample, spectral data, spectral data use

Doi

10.1016/j.molliq.2008.06.022

Identifiers