SYNERGISTIC EFFECT OF THIOCYANATE AND PERCHLORATE IONS ON TANTALUM(V) EXTRACTION WITH 3-HYDROXY-2- METHYH-PHENYI-4-PYRIDONE

The extraction of tantalum(V) from aqueous oxalic solution with 3-hydroxy-2-methyl-1 -phenyl-4-pyridone (HX) dissolved in chloroform in the presence of an excess of thiocyanate and perchlorate ions was examined at different acidities and ionic strengths. Thiocyanate and perchlorate ions produced a synergistic effect on the tantalum extraction with HX. In the presence of an excess of thiocyanate or perchlorate ions tantalum(V) was quantitatively extracted from a more acidic solution (pH 2.3 - 3 M H 2 SO 4 ) with less excess of HX and in the presence of a higher concentration of oxalic, tartaric or citric acids or their anions. Optimum conditions for the extraction of tantalum(V) as a mixed thiocyanate-HX or perchlorate-HX complex from the aqueous phase of different composition were determined. The compositions of the extracted complexes were studied and discussed.