Synthesis of a carboxylic acid extractant containing an amino group and its selective extraction of In(III) and Ga(III)

Abstract

A new extractant, [di-(2-ethylhexyl)amino]acetic acid (DEHAA), was synthesized for the mutual separation of In(III), Ga(III), and Zn(II). The extraction selectivity for the metal ions in a 1 M aqueous ammonium nitrate solution with DEHAA was In(III)>Ga(III)>Cu(II)>Zn(II), while Co(II), Cd(II), Se(IV), Se(VI), and Ni(II) were not extracted. The extraction behavior of DEHAA for In(III) and Ga(III) is different from the commercial extractant Versatic 10. The results indicate that the amino moieties in DEHAA play an important role in the selective extraction of In(III), Ga(III), and Zn(II). The extraction equilibria of In(III) and Ga(III) with DEHAA were also discussed. It is observed that In(III) and Ga(III) were extracted as 1:4 complexes, with extraction equilibria constants of KIn = 8.03×10-2 [(mol dm-3)-1] and KGa = 9.52×10-4 [(mol dm-3)-1] respectively.