Anion exchange of chromium, molybdenum and tungsten species of various oxidation states, providing the basis for separation and purification in HCl solutions

Anion exchange in HCl solutions has proved as a reliable and efficient tool for the purification of a number of transition metals. There is, however, little reliable information available concerning the anion exchange characteristics of the practically important elements in Group VIa of the Periodic Table (Cr, Mo and W). Therefore, a detailed study has been carried out to investigate the stability of the multiple oxidation states and the relevant anion exchange characteristics. Batch equilibrium results in HCl media have been verified by spectrophotometry, and new anion exchange sorption functions–indispensable for designing separations–have been proposed for the various species.