Separation of Platinum(Ⅳ) by Floatation with the Reaction System of Cetylpyridine Bromide-Potassium Bromide-Sodium Nitrate

In an aqueous solution buffered in the range of pH 2.0-4.5,and in the presence of NaNO3 (50 g·L-1),KBr (2.0×10-2mol·L-1) and cetylpyridine bromide (CPB,8.0×10-4mol·L-1),a water-insoluble ternary ion association complex,(CPB)2(PtBr6) was formed and floated at the surface of the aqueous phase giving a clear interface between the liquid and solid phases.Floatation rate of Pt(Ⅳ) of this method achieved to values over 99.6%,while values of floatation rate of some co-existing cations,i.e.,Ru(Ⅲ),Al(Ⅲ),Cr(Ⅲ),Ga(Ⅲ),Fe(Ⅲ),Rh(Ⅲ),Ni(Ⅱ),Zn(Ⅱ),Cu(Ⅱ) and Co(Ⅱ) in binary and multiple mixtures with Pt(Ⅳ) were all found to be less than 4.5%.Based on these facts,Pt(Ⅳ) was separated from the 10 cations mentioned above satisfactorily,and the proposed method was applied to the separation and photometric determination of platinum in a sample of the catalyst Ni-Pt/Al2O3,giving results of average Pt content of 0.105% (n=5),which is very close to the known value of 0.102%,and value of RSD (n=5) was found to be 1.9%.