Liquid-liquid extraction of scandium with nalidixic acid in dichloromethane

The extraction behavior of nalidixic acid (HNA) in CH ₂Cl ₂ has been studied for various di- and trivalent metal ions such as Cu(II), Fe(II), Ni(II), Mn(II), Sb(II), Co(II), Sc(III), Y(III), Nd(III) and Eu(III) from aqueous buffer solutions of pH 1-7 with 0.1 mol dm ^-3 nalidixic acid in dichloromethane. Separation factors of Sc(III) from these metals has shown that its clean separation is possible at pH 3.4-4. The parameters affecting the extraction of Sc(III) were optimized. The composition of the extracted adduct was determined by slope analysis method that came out to be Sc(NA) ₃. Extraction of Sc(III) was studied in the presence of various cations and anions. Among the anions studied only fluoride, citrate and oxalate have significant interference whereas, Fe(III) has reduced the extraction to 53% that can be removed by using ascorbic acid as reducing agent. The proposed extraction system proved good stability up to six extraction-stripping stages for the extraction of Sc(III).