Development of a Novel Extractant Derived from Kojic Acid and Its Selective Extraction for In(III) and Ga(III)

Abstract

2-Dodecylsulfanylmethyl-5-hydroxy-pyran-4-one (DSHP) containing a pyrone moiety as a ligand was synthesized in order to develop a highly selective extractant for In(III) and Ga(III). The extraction selectivity of various metal ions from 1 mol dm³ (=M) aqueous ammonium nitrate solution was examined for DSHP in toluene. Considering selective recovery of In(III) and Ga(III) from a residue of zinc refining and bauxite, In(III) and Ga(III) were selectively extracted over Zn(II) with DSHP, while Ga(III) was selectively extracted over Al(III) at low pH. This indicates that DSHP can be applied to selective separation of Ga(III) from bauxite. It was found that In(III) and Ga(III) were extracted with DSHP according to the following reaction: . The extracted complex was crystallized for analysis by ¹H-NMR. The extraction equilibrium constants for In(III) and Ga(III) with DSHP were determined to be 2.16 [-] and 3.59×10² [-], respectively. Moreover, the back extraction of In(III) and Ga(III) from the loaded organic phase was examined using various stripping agents. In(III) and Ga(III) extracted with DSHP were effectively stripped using HCl.