Mathematical modeling of iron(III) ion equilibrium for removing heavy nonferrous metals from sulfate solutions

The possible ionic equilibria in Fe2(SO4)3 water solutions were considered and the most probable of them were determined. Mathematical model of complexation in Fe2(SO4)3 solutions was developed. In this model, the ions that cause a change in the solution pH were taken into account and the generally accepted assumptions on the negligible concentrations of particles, stability constants of which are low, are not included in the model. Based on the model, the calculations of iron distribution by the ionic forms in Fe2(SO4)3 solutions with different concentrations were done with the accuracy of a few hundredths. The reliability of the proposed mathematical description of iron(III) ion equilibria was confirmed experimentally. The process of iron(III) transformation to the required complex form by mathematically predicted change of solution composition was shown. The targeted recharge of complex particles was used as a basis for separating iron(III) and heavy nonferrous metals based on the available ion-exchange resins.