SOLVENT-EXTRACTION OF URANIUM(VI) INTO TOLUENE BY DICYCLOHEXANO-18-CROWN-6 FROM MIXED AQUEOUS-ORGANIC SOLUTIONS

Extraction behaviour of uranium(VI) from mixed organo-aqueous solution s containing water-miscible protic aliphatic alcohols and several apro tic solvents was investigated by using dicyclohexano-18-crown-6-(DC18C 6) as an extractant. The organic phase was a binary solution of DC18C6 and toluene while the polar phase was a three component solution of u ranyl nitrate, polar additive and aqueous nitric acid. Methanol, ethan ol, isobutanol, dioxane, acetone, propylene carbonate and acetonitrile were used as the organic components of the mixed (polar) phase. Propy lene carbonate, acetone, acetonitrile and dioxane increased the extrac tability of U(VI), whereas alcoholic additives showed only an antagoni stic effect. The relative increase in extraction was found to be more at lower nitric acid concentrations. Possible reasons for such behavio ur are briefly discussed. Recovery of U(VI) from loaded organic phase was easily accomplished using dilute perchloric acid and sulphuric aci d. A sample method was standardized for the separation of plutonium(IV ) from uranium(VI) based on its reductive stripping.