EXTRACTION OF PALLADIUM(II) AND PLATINUM(IV) AS CHLOROCOMPLEX ACIDS INTO BASIC ORGANIC-SOLVENTS

Solvent extraction of platinum(IV) and palladium(II) with tri-n-octylamine(TOA) in o-xylene from 4.0M (Na,H)(Cl, HSO4) has been investigated at 298K in order to compare with similar extraction by trioctylphosphine oxide(TOPO). The dependence of the distribution ratio of platinum(IV) and palladium(II) on TOA, hydrogen ion and chloride ion concentrations suggests the dominant extracted species of these metals would be 2:1 for protonated amine : chlorocomplex anion and the extraction should be essentially anion exchange reaction. The extraction constants (Kex = D[H+(TOA)Cl-]o -2[Cl-]2), were evaluated as 10(6.3) and 10(5.8) for platinum(IV) and palladium(II), respectively. The anion exchange with protonated TOPO salt represented by H(TOPO)2 +Cl- is less than that with protonated TOA salt by a factor of one order.