GALLIUM SPECIATION IN AQUEOUS-SOLUTION - EXPERIMENTAL-STUDY AND MODELING .1. THERMODYNAMIC PROPERTIES OF GA(OH)(-)(4) TO 300-DEGREES-C

The solubility of pure synthetic alpha-GaOOH was measured in dilute aq ueous solutions at pH values ranging from 5 to 12.5, temperatures from 25 to 250 degrees C, and at saturated water vapor pressures. Experime ntally determined solubility constants were combined with the thermody namic properties of alpha-GaOOH (Pokrovski et al., 1996) to generate, within the framework of the revised Helgeson-Kirkham-Flowers model (Ta nger and Helgeson, 1988; Shock and Helgeson, 1988; Shock et al., 1992) , the standard partial molal thermodynamic properties at 25 degrees C and 1 bar, and revised equations of state parameters for Ga(OH)(4)(-). Thermodynamic calculations indicate that Ga(OH)(4)(-) exhibits a chem ical behavior very similar to that of Al(OH)(4)(-). Copyright (C) 1997 Elsevier Science Ltd.