Recovery of platinum and rhenium using selective precipitation induced by two-stage photochemical treatment

Abstract

Platinum(IV) and rhenium(VII) can be selectively recovered as precipitates from aqueous solution by means of UV–Visible light irradiation in the presence of 2-propanol and acetone. When an aqueous solution (pH 13.2) containing platinum(IV) (10.9 mM) and rhenium(VII) (11.5 mM) was irradiated with 60 mW cm−2 light for 3 h, 95% of initial platinum content was recovered in the precipitate in its zerovalent state with high selectivity (the recovery efficiency was 24 times that of rhenium), while 96% of the initial rhenium content remained in the reaction solution. To recover the rhenium in the remaining solution, the platinum-containing precipitate was removed, and the collected solution was further irradiated in another photochemical cell. After 12 h of the second irradiation, 82% of the rhenium content in the initial solution (before the first irradiation) was recovered as a precipitate with a recovery efficiency that was 16 times that of platinum. Using this two-stage photochemical treatment, both the platinum and rhenium in the aqueous solutions were successfully recovered as precipitates with high selectivity.