Solvent extraction of uranium(VI) by 3-hydroxy-2-methyl-1-phenyl-4-pyridone

The extraction of uranium (VI) from aqueous hydrochloric or nitric acid solution by 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) dissolved in chloroform has been studied. Uranium(VI) is quantitatively extracted from the solutions in the range 5 <= pH <= 9. With increasing acid concentration, the extraction of uranium diminishes and at 1 M acid practically all the uranium remains in the aqueous phase. The quantitative back-extraction of uranium from the organic phase is possible with HCl or HNO3 at concentrations higher than 1 M. The composition of the extracted uranium(VI) species was studied in solution and in the solid state. The complex UO2X2HX was isolated from the chloroform solution. Solutions in chloroform, exhibit maximum absorbance at 319 nm; the molar absorptivity is 32,000 1 mole -1cm-1. Uranium can be determined spectrophotometrically in the organic phase. (author)