水-正丙醇-硫酸铵体系析相萃取分离钯的研究

研究了水-正丙醇析相萃取Pd(Ⅱ)的行为及Pd(Ⅱ)与一些金属离子分离的条件。结果表明, 硫酸铵能使正丙醇的水溶液分成两相，在分相过程中，Pd(Ⅱ)与溴化钾生成的PdBr₄^2-与质子化正丙醇 (C₃H₇OH₂⁺)形成缔合物PdBr₄^2-C₃H₇OH₂⁺]₂能被正丙醇相完全萃取。当溶液中正丙醇的体积分数、溴化钾浓度和硫酸铵的质量浓度分别为30 %, 7.0×10-3 mol/L, 0.2 g/ mL且pH 2.0时, Pd的萃取率达到96.7%以上，而Ag(Ⅰ)、Cu(Ⅱ)、Fe(Ⅲ)、V(Ⅴ)、Ni(Ⅱ)、W(Ⅵ)、Al(Ⅲ)、Pb(Ⅱ)、Cr(Ⅲ)、U(Ⅵ)、Mg(Ⅱ)、Bi(Ⅲ)基本不被萃取，实现了Pd(Ⅱ)与上述金属离子的分离。对合成水样和钯镍电镀液中的钯进行了定量萃取分离和测定，获得了满意结果。

Study on separation of palladium by phase separation extraction in water-1-propanol-ammonium sulphate system

The phase separation and extraction of Pd(Ⅱ) with water-1-propanol was investigated, as well as the separation conditions of Pd(Ⅱ) from other metal ions. The results showed that the water-1-propanol solution could be divided into two phases in presence of ammonium sulphate. In this phase separation process, the association complex ［PdBr₄^2-］［C₃H₇OH₂⁺]₂, which was formed by protonated 1-propanol (C₃H₇OH₂⁺) and PdBr₄^2-, could be fully extracted by 1-propanol. The extraction efficiency of Pd(Ⅱ) was up to 96.7 % at pH 2.0 when the concentrations of 1-propanol, potassium bromide and ammonium sulphate were 30 % (V/V), 7.0×10-3 mol/L and 0.2 g/mL, respectively. Under the same condition, other metal ions including Ag(Ⅰ), Cu(Ⅱ), Fe(Ⅲ), V(Ⅴ), Ni(Ⅱ), W(Ⅵ), Al(Ⅲ), Pb (Ⅱ), Cr(Ⅲ), U(Ⅵ), Mg(Ⅱ) and Bi(Ⅲ) were not extracted, realizing the separation of Pd(Ⅱ) from these metal ions. This method was applied to the extraction separation and determination of Pd(Ⅱ) in synthetic water and Pd-Ni electroplating solution with satisfactory results.