The solubility of magnetite and hydrolysis of ferrous ion in aqueous solutions at elevated temperatures

摘要: Abstract The solubility of magnetite (Fe3O4) in dilute aqueous solutions saturated with H2 at 1 atm 25 °C has been measured temperatures between 50 and 300 °C. have ranged from KOH molality 400 × 10−6 mol kg−1 to HCl 100 kg−1. measurements were made by the continuous flow solution over a bed specially prepared pure magnetite. It was found that, under these conditions temperature hydrogen activity, Fe3O4 does not transform HFe5O8 or γ-Fe2O3. results fitted scheme soluble species consisting Fe2+, FeOH+, Fe(OH)2, Fe(OH)3−, equilibrium constants for reactions ( 3 Fe O 4 + (2−b)H H 2 (g) = Fe(OH) (2−b)+ b calculated. coefficients Fe2+ FeOH+ be negative, those Fe(OH)2 positive. estimated values ΔHo ΔSo are also given. value log10(K/mol kg−1) reaction 2+ FeOH , determined extrapolation solubilities (−9.3 ± 0.5). combined other thermodynamic data calculate ΔGo, ΔHo, formation reaction: bH (2−b) . extrapolated ΔGo this gives an Eo (0.475 0.010) V.