Selective Separation of Platinum in the Propyl-alcohol-Sodium Sulfate Two-phase Aqueous Extraction System

Abstract

The extraction separation and phase distribution behaviours of iodide

complexes of platinum(IV) in propyl-alcohol-sodium sulfate two-phase

aqueous extraction system have been investigated. The amount of Na₂SO₄

added, the initial volume of propyl alcohol and the acidity of the system

are mainly factors affecting the formation and phase separation of the

aqueous two-phase system. Platinum(IV) is found to be extracted into

the propyl alcohol phase due to ion pair formation of platinum(IV) as

[Pt I₆^2-·2(PrOH₂⁺)₂] in the presence of KI and HCl medium. The experimental

results indicate that platinum can be quantitatively and highly

selectively extracted by the optimized method, using which > 99.0 %

extraction efficiency can be achieved. The proposed method has been

successfully applied to the selective separation of platinum from samples

containing large amount of base metals including Fe²⁺, Ca²⁺, Mg²⁺, Mn²⁺,

Al³⁺, Pb²⁺ and Zn²⁺ in synthetic sample and exhibits high selectivity to

platinum.