Sorption of Rhenium from Sulfuric Acid Solutions with Trialkylamine-Containing Impregnates

Resumo

The sorption of rhenium (VII) from sulfuric acid solutions with impregnates based on macroporous polymeric carriers (copolymers of styrene with divinylbenzene, a weakly acidic cation-exchange resin), which contain technical trialkylamine (TAA), is investigated in batch conditions. Equilibrium and kinetic characteristics of sorption of rhenium with the K-TAA impregnate based on macroporous cationite having the best capacitive characteristics with respect to rhenium are found. The maximal distribution coefficient of rhenium in the K-TAA impregnate is observed during sorption from solutions with pH 2. The sorption isotherm of rhenium is described by the Langmuir equation with constant K = 29 ± 2 mL/g. Integrated kinetic curves of sorption are found by the method of a limited solution volume at various temperatures and effective diffusion coefficients of rhenium in an impregnate, which are equal to 3.8 × 10^–11 (295 K) and 1.3 × 10^–10 (308 K) m²/s, are calculated allowing to the half-transformation time. Processing the kinetic data by linearization according to equations of models of the pseudo-first, pseudo-second, internal diffusion, and Elovich showed that kinetic curves are described with the highest degree of correlation by pseudo-second-order equations with rate constants 0.00056 (295 K) and 0.00059 (308 K) g mg^–1 min^–1. The apparent activation energy of sorption of rhenium of 39 ± 2 kJ/mol is calculated according to the Arrhenius equation. The K-TAA impregnate is approved for the sorption of rhenium from the eluate formed during the desorption of rhenium from the weakly basic anion-exchange resin (Purolite A170) preliminarily saturated with rhenium from a productive leaching solution of processing products of rhenium-containing off-balance copper-sulfide ores with a complex composition.