Effect of capriquat on the extraction of cobalt (II)-, nickel (II)-and copper(II)-2-thenoyltrifluoro-acetonate complexes

Abstract

Effect of Capriquat (trioctylmethylammonium chloride) on the extraction of Co(II), Ni(II) and Cu(II) with 2-thenoyltrifluoroacetone (TTA= Htta) was studied. The experimental procedure was as follows: An aqueous solution (10.0 ml) containing metal ion (M2+) and acetate buffer solution (pH=4.75) was taken in a separatory funnel. An equal volume of the extractant solution which is a mixture of TTA and Capriquat in benzene was added. The mixture was then shaken, and the absorbance of the organic phase was measured. Concentrations of the remaining nickel(II) and cobalt(II) in the aqueous phase were determined by spectrophotometry. Both of the valence-saturated chelate M(tta)2 and the co-ordination-saturated complex M(tta)3- could be formed and extracted into benzene in the presence of Capriquat. The extraction of the former chelate was observed to occur in lower concentration region of TTA or Capriquat, and the extraction rates for Co(tta)2 and Ni(tta)2 were accelerated by the addition of Capriquat. However, the formation of Co(tta)3-and Ni(tta)3- from M(tta)2 was found to be very slow. In contrast, the rates of extraction for Cu(tta)2 and Cu(tta)3- were very high, and the above equilibria were reached within 10 seconds. © 1975, The Japan Society for Analytical Chemistry. All rights reserved.