氯化钠-正丙醇-硫氰酸铵-水体系析相萃取分离和富集锡(Ⅳ)

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

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)、0.09mol/L和0.17g/mL时,Sn(Ⅳ)的萃取率在98.3%以上,Fe(Ⅳ)、Ni(Ⅳ)、Pb(Ⅳ)、Al(Ⅲ)、Mg(Ⅳ)、Mn(Ⅳ)、Ce(Ⅲ)、Cr(Ⅲ)、Zn(Ⅳ)、Ag(Ⅰ)、Cd(Ⅳ)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%。

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）,0.09mol/L and 0.17g/mL,respectively,the extraction yield of stannum？ was more than 98.3%.Simultaneously,Fe（Ⅳ）、Ni（Ⅳ）、Pb（Ⅳ）、Al（Ⅲ）、Mg（Ⅳ）、Mn（Ⅳ）、Ce（Ⅲ）、Cr（Ⅲ）、Zn（Ⅳ）、Ag（Ⅰ）、Cd（Ⅳ） 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%.