Gallium speciation in aqueous solution. Experimental study and modelling: Part 1. Thermodynamic properties of Ga(OH) 4− to 300°C

Abstract

The solubility of pure synthetic α-GaOOH was measured in dilute aqueous solutions at pH values ranging from 5 to 12.5, temperatures from 25 to 250°C, and at saturated water vapor pressures. Experimentally determined solubility constants were combined with the thermodynamic properties of α-GaOOH (Pokrovski et al., 1996) to generate, within the framework of the revised Helgeson-Kirkham-Flowers model (Tanger and Helgeson, 1988; Shock and Helgeson, 1988; Shock et al., 1992), the standard partial molal thermodynamic properties at 25°C and 1 bar, and revised equations of state parameters for Ga(OH) 4 −. Thermodynamic calculations indicate that Ga(OH) 4 − exhibits a chemical behavior very similar to that of Al(OH) 4 −.