The Solvent Extraction of Metal Ions from Sulfuric Acid Solutions with a Mixed Extractant—Long-chain Primary Amine and Di-2-ethylhexylphosphoric Acid

Abstract The distribution of metal ions between phases of dilute sulfuric acid and carbon tetrachloride containing long-chain primary amine (Primene JM) and di-2-ethylhexylphosphoric acid (D2EHPA) has been investigated. The degree of the extraction of bi- and tervalent metal ions, such as zinc, iron (III), indium, lanthanum, and cerium(III), is found to be the lowest when the organic phase contains 5 g/l of Primene JM and 7–8 g/l of D2EHPA, while a minimum extraction of thorium occurs at a different composition of the organic phase. Thus, thorium can be quantitatively separated from most other metals by extraction from a 0.1n sulfuric acid medium with carbon tetrachloride containing 5 g/l of Primene JM and 7–8 g/l of D2EHPA. Under these extraction conditions, a single extraction is sufficient for the quantitative separation of thorium from high concentrations of lanthanide metals. Contrary to the usual method of extraction using long-chain amines, which involves a tedious multiple extraction, the mixed-extractant technique described is simple and will find many uses in the determinations of thorium in a variety of samples.