Solvent extraction separation of antimony(III) and bismuth(III) with bis (2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302)

Solvent extraction separation of antimony(III) and bismuth(III) was carried out from aqueous acidic solutions with Cyanex 302 in toluene. Quantitative extraction of antimony(III) was observed in the acidic range of 0.1-1.0 M H2SO4 and 0.1-2.0 M HCl with 8.5 x 10(-2) M Cyanex 302 in toluene, whereas that of bismuth(III) was observed in the acidic range of 0.01-0.1 M HNO3 an d 0.01-0.1 M HCl with 1 x 10(-2) M Cyanex 302 in toluene. Antimony(III) fro m the organic phase was stripped with 8.5 M H2SO4 and determined spectropho tometrically by the iodide method at 425 nm. Bismuth(III) from the organic phase was stripped with 2 M HNO3 and determined spectrophotometrically by t he thiourea method at 470 nm. The optimum extraction conditions were evalua ted by a critical study of acidity, extractant concentration, period of equ ilibrium and effect of diluents. Separation of bismuth(III) and antimony(II I) from one another in varying ratios of 1:1, 1:2, 1:4, 2:1 and 5:1 and mul ticomponent mixtures of commonly associated metals was found to be possible by this method. It was successfully applied for analysis of antimony and b ismuth in real samples. (C) 1999 Elsevier Science B.V. All rights reserved.