Kinetic modeling of adsorption of vanadium and iron from acid solution through ion exchange resins
(Department of Chemical Engineering, Polytechnic School of the University of S？o Paulo (USP), Rua do Lago, 250, 05508-080, S？o Paulo, SP, Brazil)
Abstract: This study assessed the adsorption process and the reaction kinetics involved in the selective recovery of vanadium from an acid solution containing iron as an impurity. Four commercial resins were studied: Lewatit？ MonoPlus TP 209 XL, Lewatit？ TP 207, Dowex？ M4195 (chelating resin) and Lewatit？ MonoPlus S 200 H (strong cationic exchange resin). To investigate the effect of time on the adsorption process, batch experiments were carried out using the following initial conditions: pH 2.0, 298 K, and a proportion of 1 g of resin to 50 mL of solution. The variation of pH over time was analyzed. Chelating resin released less H+ ions as the adsorption occurred, resulting in a lower drop of pH when compared to S 200 H resin. Ion adsorption by the resins was also evaluated through FT-IR and SEM-EDS before and after the experiments. Among the evaluated kinetic models (pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models), the pseudo-second order model best fits the experimental data of the adsorption of vanadium and iron by all of the four resins. M4195 resin showed the highest recovery of vanadium and the lowest adsorption of iron. Kinetic data, which are fundamental to industrial processes applications, are provided.
Key words: vanadium recovery; adsorption; chelating resins; metal ions; cation exchange resin; batch experiments