Highly efficient homogeneous liquid-liquid extraction of lanthanoid ions in a strong acidic solution

Thirteen lanthanoids were extracted from a strong acid solution (approximately pH 1) by a homogeneous liquid-liquid extraction method {i.e. the perfluoro-octanic acid (HPFOA) /acetone system using the pH-dependent phase separation phenomenon) with the phosphoric acid, di(2-ethlyhexyl)ester (D2EHPA). In the proposed method, the extraction percentage of each lanthanoid(III) was 85 similar to 95%. After phase separation, the volume ratio (V-w / V-s) of the aqueous phase (V-w) and the sedimented liquid phase (V-s) was 1,580 (47.5 ml double right arrow 30 mu l). The extracted lanthanoid ion species was examined using a normal solvent extraction method using the water/cyclohexane system. This method was done by changing the respective concentration of D2EHPA, HPFOA and sodium acetate. As a result, the extracted lanthanoid ion species was assumed to be a complex of [metal:D2EHPA=1:3].