Purification of an iron contaminated vanadium solution through ion exchange resins

The present work aimed to study the behavior of four ion exchange resins: Lewatit®️ MonoPlus TP 209 XL, Lewatit®️ TP 207, Dowex™️ M4195 (chelating resins) and Lewatit®️ MonoPlus S 200H (strong cationic exchange resin) in the selective recovery of vanadium from an acid solution containing iron as an impurity. Batch experiments were carried out to evaluate the influence of parameters such as pH (0.50–2.00), resin mass (0.055–9.000 g) and temperature (293–328 K). Ion-adsorption mechanisms of the resins and thermodynamic parameters of adsorption reactions were evaluated. Increasing the pH from 0.50 to 2.00 favored the adsorption of both iron and vanadium by the resins. Chelating resins were more selective for vanadium than S 200H resin. Vanadium adsorption better adjusted to the Langmuir isotherm for the TP 209 XL, TP 207 and S 200H resins, while M4195 adjusted better to the Temkin isotherm. The iron adsorption mechanism, however, varied between the Langmuir, Freundlich and Temkin models. The positive values of ΔH0 expressed the endothermic nature of the vanadium adsorption process for the three chelating resins and for iron in all of them. Furthermore, negative ΔG0 values revealed a spontaneous character of the adsorption of both metals to all of the resins. In terms of mass of adsorbed ions, chelating resins showed good selectivity for vanadium compared to iron and these are, therefore, promising to obtain pure vanadium solutions in greater scale operations.