SOLVENT-EXTRACTION OF ANTIMONY (III), BISMUTH (III), LEAD (II) AND TIN (IV) WITH BIS(2,4,4-TRIMETHYLPENTYL)PHOSPHINODITHIOIC ACID (CYANEX 301)

The solvent extraction of antimony (III), bismuth (III), lead (II) and tin (IV) from aqueous hydrochloric acid solutions by bis(2,4,4-trimethylpentyl) phosphinodithioic acid (Cyanex 301 (R) denoted HL) in kerosene + 10 % v/v n-decanol was investigated. Lead (II), tin (IV), bismuth (III) and antimony (III) are efficiently extracted by Cyanex 301 (R) up to about 5, 6, 9 and 11 mol.L-1 HCl, respectively. The corresponding extracted species were identified as PbL2, SnCl2L2, BiL3 and SbL3. However, it was observed that Sn (IV) can be moderately extracted from the aqueous phase by the mere mixture of kerosene and n-decanol above 9 mol.L-1 HCl. In all cases, extraction equilibrium was reached within a few minutes. Finally, a thermodynamic modelling of the extraction system was developed in the particular case of lead (II).