Separation of tungsten and rhenium on alumina

Abstract

The conditions for the efficient separation of tungsten(VI) and rhenium (VII) on alumina were established. The distribution coefficients K d for tungstate and perrhenate anions, as well as the separation factors ?(? = KdWO42-/Kd ReO4-) were determined using hydrochloric or nitric acid as the aqueous media. Asolution of sodium chloride in the pH range 2?6 was also examined. Under all the tested experimental conditions, alumina is a much better adsorbent for tungsten than for rhenium. The obtained results indicated that the best separation of these two elements is achieved when 0.01? 0.1 mol dm-3HCl or 1.0mol dm-3 HNO3 are used as the aqueous media. If NaCl is used as the aqueous phase, the best separation is achieved with 0.20 mol dm-3 NaCl pH 4?6. Under these experimental conditions, the breakthrough and saturation capacities of alumina for tungsten at pH4 are 17 and 26 mg W/g Al2O3 respectively. With increasing pH, these values decrease. Thus, at pH 6 they are only 4 and 13 mg W/g Al2O3, respectively.