Hydrolysis of Co(II) at elevated temperatures

Abstract

Hydrolysis of Co(II) has been studied up to 200 °C using a concentration cell with liquid junction of the type Pt(H2)|H+(a1)||H+(a2)|(H2)Pt. The effect of varying the initial solution pH and cobalt concentration has been studied at different ionic strengths. The hydrothermal hydrolysis for cobalt solutions between pH 3.9 and 9.6 is consistent with the equilibrium Co2+ + H2O → CoOH+ + H+. Higher hydrolytic species are not important. Hydrolysis increases with temperature and produces a buffering action at 200 °C. Thermodynamic quantifies for the hydrolysed species are reported.