氯化钠-正丙醇-硫氰酸铵-水体系析相萃取分离和富集锡(Ⅳ)

研究了氯化钠-正丙醇-硫氰酸铵-水体系析相萃取分离和富集Sn(Ⅳ)的行为及与一些金属离子分离的条件。结果表明, 氯化钠能使正丙醇的水溶液分成两相,在分相过程中,Sn(Ⅳ)和硫氰酸铵生成的Sn(SCN)_5~6]^(5~6)-4]-与质子化正丙醇C₃H₇OH₂⁺ 形成的缔合物Sn(SCN)_5~6]C₃H₇OH₂]_1-2能被正丙醇相完全萃取。固定溶液酸度为pH 2,当正丙醇、硫氰酸铵和氯化钠的浓度分别为30%(V/V)、0.09 mol/L和0.17 g/mL时, Sn(Ⅳ)的萃取率在98.3%以上,Fe(Ⅱ)、Ni(Ⅱ)、Pb(Ⅱ)、Al(Ⅲ)、Mg(Ⅱ)、Mn(Ⅱ)、Ce(Ⅲ)、Cr(Ⅲ)、Zn(Ⅱ)、Ag(Ⅰ)、Cd(Ⅱ)和V(Ⅴ)不被萃取,实现了Sn(Ⅳ)与上述金属离子的分离。方法用于Pb-Ca-Sn-Al合金中Sn的分离和测定,平均回收率为97.4%,相对标准偏差(n=7)为2.1%。

Separation and enrichment of stannum (Ⅳ) by phase extraction in sodium chloride-1-propanol-ammonium thiocyanate-water system

The behavior and conditions for extraction separation and enrichment of stannum (Ⅳ) from other metal ions in sodium chloride-1-propanol-ammonium thiocyanate-water system were investigated. The results showed that 1-propanol aqueous solution could be well divided into two phases in presence of sodium chloride. During the phase separation process, Sn(SCN)_5~6] ^(5~6)-4]- formed from stannum (Ⅳ) and ammonium thiocyanate could reacted with protonized 1-propanol of C₃H₇OH₂⁺ to form associated complex of Sn(SCN)_5~6]C₃H₇OH₂]_1-2, which could be fully extracted by 1-propanol phase. When acidity of the solution was fixed at pH 2.0, and the concentration of 1-propanol, ammonium thiocyanate and sodium chloride was 30%(V/V), 0.09 mol/L and 0.17 g/mL, respectively, the extraction yield of stannum(Ⅳ) was more than 98.3%. Simultaneously, Fe(Ⅱ), Ni(Ⅱ), Pb(Ⅱ), Al(Ⅲ), Mg(Ⅱ), Mn(Ⅱ), Ce(Ⅲ), Cr(Ⅲ), Zn(Ⅱ), Ag(Ⅰ), Cd(Ⅱ)and V(Ⅴ) could not be extracted, realizing the separation of stannum (Ⅳ) from these metal ions. The method has been applied to the separation and determination of stannum (Ⅳ) in Pb-Ca-Sn-Al alloy sample with recovery of 97.4% and relative standard deviation(n=7) of 2.1 %.