Thermodynamic properties of the Sb(III) hydroxide complex Sb(OH)3(aq) at hydrothermal conditions

The standard thermodynamic properties and Helgeson-Kirkham-Flowers (HKF) parameters for Sb(OH)3(aq) have been estimated. For this purpose, the available solubility data for senarmontite, valentinite, stibnite, and native Sb in a wide range of temperatures (15 to 450°C) and pressures (1 to 1000 bar), and thermodynamic properties of Sb oxides (senarmontite and valentinite) have been critically analyzed. Published data were complimented by results from new experiments performed by solubility and solid-state galvanic cell methods. Both experimental data and thermodynamic calculations show that the hydroxide complex Sb(OH)3(aq) is primarily responsible for hydrothermal transport of antimony, especially at temperatures above 250°C.