Separation and recovery of gallium(III) ions from aqueous phase by liquid--liquid extraction using a novel extractant, Cyphos IL 101


Abstract: The present study describes the extraction behavior of gallium(III) using a novel ionic liquid trihexyl(tetradecyl) phosphonium chloride (Cyphos IL 101) diluted with kerosene from acidic chloride medium. The extraction of gallium was found to depend on the hydrochloric acid concentration and quantitative extraction of gallium took place at 2.0 mol/L HCl concentration. The nature of the extracted complex in the organic phase was determined using Job's method and proposed to be [R$_{3}$R$^\prime $PGaCl$_{4}$]. The loading capacity of 5.0 $\times$ 10$^{-3}$ mol/L Cyphos IL 101 was determined to be 320.0 mg/L. Two stages of stripping were required for complete removal of gallium from the loaded organic phase using 0.1 mol/L HCl. From the temperature variation study, the extraction process was found to be endothermic. The separation efficiency of gallium from its associated metal ions such as Al(III), Fe(III), Zn(II), Cu(II), and Ni(II) was investigated from binary mixtures and in the presence of all these metal ions, which revealed that the extraction of Zn(II) and Cu(II) were more preferred to Ga(III) while extractions of Al(III) and Ni(II) were nil. The potential of the extractant was assessed to recover gallium from photodiodes.

Keywords: Gallium, Cyphos IL 101, extraction, separation

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