Simultaneous sorption recovery of platinum and rhodium from sulfate–chloride solutions

The present work is devoted to simultaneous ion exchange recovery of platinum(II, IV) and rhodium(III) from sulfate–chloride solutions, freshly prepared and stored over 3 months, on commercial macroporous anion exchangers with different chemical structures. The sorption was carried out from solutions with 2.0; 0.1 and 0.01 mol/L HClHCl and H2SO4H2SO4. The initial concentrations of platinum and rhodium in contacting solutions were 0.05–5.0 mmol/L. Sorption and kinetic properties of selected anion exchangers were investigated and the basic parameters of ion exchange capacity, recovery, distribution coefficients, separation factors, process rate, diffusion coefficients and half-exchange times were calculated. It was shown that the anion exchangers possess high sorption ability towards platinum and rhodium during their recovery from freshly prepared and stored sulfate–chloride solutions. The optimal molar ratio of hydrochloric and sulfuric acids was determined as 1:1. It was shown that freshly prepared sulfate–chloride systems have the same efficiency during simultaneous Pt/RhPt/Rh recovery as chloride solutions. In case of stored systems, the sulfate–chloride solutions compare favorably with chloride ones.

► Simultaneous ion exchange recovery of Pt and Rh from sulfate–chloride solutions was studied. ► Sorption recovery is optimal at the molar ratio HCl:H2SO4=HCl:H2SO4= 1:1. ► Efficiency of sulfate–chloride stored solutions compares favorably with chloride stored solutions.