Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 4

A method for the selective removal of indium from solutions (sol.) of acid leaching of Waelz zinc oxide (0.02–0.1 g/dm³ In) was proposed. It is an alternative technique for extraction. Adsorption over modified montmorillonite that is the Меtоsol reagent (reag.) in dynamic mode allows maximally implementing the reagent exchange capacity with the optimum cycle of sorption/desorption operations. Adsorption of iron (II) and zinc ions in static mode was detected. It is driven by the formation of intermolecular bonds with the developed surface of modified aluminosilicate. The formation of a stationary front of indium ion sorption from a polycomponent solution over the Меtоsol mineral sorbent due to predominant adsorption of In³⁺ compared to Fe²⁺ and Zn²⁺ was found in dynamic mode. The latter cations are replaced by In³⁺ ions that form chelates with ionogenic groups of di(2-ethylhexyl)phosphoric acid. Output curves of sorption of In ions at unit load V_sol/V_reag = 1–2.7 h^–1 and temperatures of 298–328 K are mainly S-shaped. The inflection point is shifted to the low-value range of the specific volume of the past solution (V_sol/V_reag), which indicates slowing down the ion diffusion rate in sorbent. Indium ions passing into the filtrate comes much earlier (V_sol(1)/V_sol = 3.33–0.66), the width of the chromatographic front (ΔV_sol /V_reag = 12.1–12.35) increases, the full dynamic exchange capacity (FDEC = 0.572–0.237 µmol-eq/g) and the utilization rate of the resin bed are decreased with increasing the linear rate (ω_0.5) of the transmission of the eluent through a column in the range 4.78 to 12.74 cm/h. The width of the chromatographic front (ΔV_sol /V_reag = 12.1–10.24) decreases; the full dynamic exchange capacity (FDEC = 0.572–1.293 mol-eq/g) and the utilization rate of the resin bed (η = 0.226–0.256) are increased, which testifies monitoring the process of sorption of indium by mixed diffusion. The Меtоsol reagent allows selectively extracting indium from production solutions in dynamic mode.