Synthesis of new extractants containing a carboxylic acid group and their extraction equilibria with indium(III), gallium(III) and zinc(II)

Abstract

Two types of carboxylic acid with alkyl chains as novel extraction agents were synthesized for the selective extraction of indium(III) and gallium(III) from acidic media. Liquid-liquid extraction tests were carried out to examine their extraction abilities for the metal ions. The selectivity for metal ions with 2-(4-nonylphenoxy) acetic acid (AO), 2-[(4-octylphenyl)amino] acetic acid (AN), and VersaticlO were in the following order: In(IH)≈Ga(III)>Zn(II). The newly synthesized extractants AO and AN showed high extraction abilities compared with VersaticlO. The extraction equilibria of indium(III), gallium(III), and zinc(II) by a batchwise method at 303 K with AO were quantitatively investigated. Indium (III) and gallium(III) were extracted with AO (HR) according to the following reaction: M3++ 2.5(HR)2 ⇋ MR3(HR)2 + 3H+ (M: In, Ga). Zinc(II) was extracted with AO (HR) according to the following reaction: Zn2+ + 1.5(HR)2 ⇋ ZnR2(HR) + 2H+. The extraction equilibrium constants for indium(III), gallium(III) and zinc(II) with AO were determined to be 8.8×<10-5 [(mol dm -3)0.5], 2.0×10-5 [(mol dm -3)0.5], and 3.0×10-3 [-], respectively.