Liquid-liquid extraction and recovery of gallium(III) from acid media with 2-octylaminopyridine in chloroform: Analysis of bauxite ore

Abstract

The liquid-liquid extraction of gallium(III) from hydrochloric acid solution using 2-octylaminopyridine (2-OAP) in chloroform was investigated. The extraction of gallium(III) from 6.0-9.0 mol dm-3 hydrochloric acid was found to be quantitative using 0.033 mol dm-3 2-OAP in chloroform. The effect of the reagent concentration and other parameters on the extraction of gallium(III) was also studied. The stoichiometry of the extracted species of gallium(III) was determined based on the slope analysis method. The extraction reaction proceeded via the anion exchange mechanism from hydrochloric acid and the extracted species was [RR?NH2+GaCl4-]org. The extraction of gallium(III) was performed in the presence of various ions to ascertain the tolerance limit to individual ions. The temperature dependence of the extraction equilibrium constants was examined to estimate the apparent thermodynamic functions (?H, ?S and ?G) for the extraction reaction. Gallium(III) was successfully separated from commonly associated metal ions, such as Zn(II), Pb(II), Cd(II), Hg(II), Bi(III), Al(III), Se(IV), Sb(III), Sn(IV), In(III), Tl(I) and Tl(III). However, gallium(III) was separated from Fe(III) from weak organic acid media. The procedure was also extended to the determination of gallium(III) in bauxite ore by the standard addition method.