Acidic organophosphorus extractants—XVI Effect of tri- n-butyl phosphate on the extraction of some metals by di-(2-ethylhexyl) phosphoric acid in n-hexane

Abstract

Tri- n-butyl phosphate (TBP) causes only an antagonistic effect on the extraction of Eu(III), Am(III), Zr(IV) and Nb(V) by di(2-ethylhexyl) phosphoric acid (HDEHP) in n-hexane from aqueous solutions containing perchlorate, citrate and nitrilotriacetate at log [H +] = −2·87 and in extracting Eu(III) from a perchlorate solution at log [H +] = −0·70. A weak synergic effect occurs in the extraction of Sr(II) from solutions containing perchlorate and citrate at log [H +] = −2·87. The complexes Eu A 3 . H A . yB (with A, H A and B denoting the anion of HDEHP, the molecule of HDEHP and the molecule of TBP respectively), Eu A 3 . yB and possibly also Eu A 2(ClO 4) . yB are extracted from 0·2 M HClO 4 + 0·8 M NaClO 4. With 0·10 M citric acid +0·15 M monosodium citrate +0·85 M NaClO 4 as the aqueous phase, the complexes Eu A 3 . 3H A, Am A 3 . 3H A′, Sr A 2 . 2H A. B and Sr A 2 . 2H A . 2 B prevail in the organic phase at the TBP concentration 0·08−0·1 F, while the complexes Eu A 3 . H A . yB, Am A 3 . H A. yB, Sr A 2 . yB, Sr A 2 . H A. yB and probably also Sr A 2 . 2H A . yB are formed at 1·0 F TBP. The value of y in the above complexes could not be determined.