SOLVENT EXTRACTION OF AMERICIUM(Ⅲ) FROM AQUEOUS NITRATE MEDIA BY DI-n-OCTYL SULFOXIDE(DOSO)

The extraction behaviour of Am(III) from dilute nitric acid media withDOSO in xylene was investigated. It is necessary to use salting-out agents becauseof the low distribution coefficient of Am. The effect of some variablessuch as acidity, extractant concentration, salting-out agent and temperature onmetal extraction by DOSO was examined systematically. Results indicated that theextractability of Am decreased rapidly with the increase of the acidity in aqueousphase, increased with the increase of the concentration of the extractant and thesalting-out agent, and decreased with the elevation of temperature. The salting-out strength follows the sequence: Al(NO_3)_3>Mg(NO_3)_2>Ca(NO_3)_2>LiNO_3>NaNO_3>NH_4NO_3. The species extracted might be in the form Am(NO_3)_3·3DOSO.Americium was easily stripped with 1-3 mol/l HNO_3 solution from the loadedorganic phase. The extractability of Am greatly increased after the addition of some non-aqueous solvent such as acetone and acetonitrile. There was an obvious synergeticeffect in a mixture of TBP and DOSO in xylene.