ANION-EXCHANGE STUDIES ON HYDROUS CHROMIUM-OXIDE

The oxyanion exchange and adsorption behaviour of chromate, molybdate, phosphate and dichromate have been studied in acidic and basic media over hydrous chromium oxide predried at 37 degrees C. The distribution coefficient (K-d) is pH dependent and the selectivity is in the order Cr2O7-2 > MoO4-2 > CrO4-2 > PO4-3. The polyvalent anions are strongly adsorbed in acidic media and cannot be eluted under me prevailing exp erimental conditions, whereas sodium hydroxide is found to be an effec tive eluent.