LIQUID-LIQUID EXTRACTION AND SEPARATION OF GALLIUM (III), INDIUM (III), AND THALLIUM (III) BY CYANEX-925

Abstract

A study of liquid-liquid extraction behavior of gallium (III), indium (III), and thallium (III) with Cyanex-925 (Bis-2,4,4-trimethyl pentyl-n-octyl phosphine oxide) was undertaken. Both gallium (III) and indium (III) were coextracted in the pH range 4.0–5.0 while thallium (III) was extracted between pH 2.0 and 4.0. The gallium, indium, and thallium ions were stripped out from the organic phase with 1.0 mol/L HNO₃, 1.5 mol/L HCl, and 3.0 mol/L HCl, respectively. The optimum conditions of extractability were found separately as functions of pH, temperature, equilibrium time, and stripping ability. Based on these results, a sequential method was developed for the separation of gallium (III), indium (III), and thallium (III).

Keywords:

• Liquid-liquid extraction
• Separation
• Gallium (III)
• Indium (III)
• Thallium (III)
• Cyanex-925
• % Recovery

ACKNOWLEDGMENT

The authors are thankful to Cytec Industries Inc, Canada, for the gift sample of Cyanex-925.