Tri-n-butyl phosphate as an extracting solvent for inorganic nitrates—II Yttrium and the lower lanthanide nitrates

Abstract

Tri- n-butyl phosphate (TBP) can be used to extract and separate yttrium and the lower lanthanides (lanthanum-gadolinium). Extraction from nitric acid solutions generally increases with acidity, sometimes very steeply, though there is often a region of fallin partition coefficients between say 4 and 7 M HNO 3. Extraction at low acidity but high nitrate ion concentration (added, for example, as sodium nitrate) is usually high. Extractability increases with atomic number in the lanthanide series, with yttrium more extractable than any lanthanide at acidities > c. 5 M HNO 3, though less extractable at low acidities. The separation factors for successive lanthanides increase with acidity and reach values as high as 2. They are also high in systems of low acidity but high nitrate concentration, and in presence in TTA (thenoyl-trifluoracetone) in the organic phase. Experiments at varying TBP concentrations indicate the formation of Y(NO 3) 3·3TBP and Ce(NO 3) 3·3TBP. (See also note added in proof).