在pH 2.0~4.5的水溶液中,铂(Ⅳ)与溴化钾、溴化十六烷基吡啶(CPB)形成不溶于水的三元缔合物(CPB)2(PtBr6),浮选析出于水相上层分成界面清晰的液-固两相.当溶液中硝酸钠、溴化钾、溴化十六烷基吡啶的浓度分别为50 g·L-1、2.0×10-2mol·L-1和8.0×10-4mol·L-1,pH为3.0时,能使铂(Ⅳ)的浮选率达到99.6%以上,而在铂(Ⅳ)与以下离子,即钌(Ⅲ)、铝(Ⅲ)、铬(Ⅲ)、镓(Ⅲ)、铁(Ⅲ)、铑(Ⅲ)、镍(Ⅱ)、锌(Ⅱ)、铜(Ⅱ)和钴(Ⅱ)共存的二元和多元混合物中,上述各共存离子的浮选率均小于4.5%.据此提出了浮选分离和富集铂(Ⅳ)的方法,应用于一种催化剂Ni-Pt/Al2O3催化剂样品中铂的分离和测定,测得铂量的平均质量分数为0.105%,与其已知值相符.测定值的相对标准偏差(n=5)为1.9%.

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%.