Separation and enrichment of stannum (Ⅳ) by phase extraction in sodium chloride-1-propanol-ammonium thiocyanate-water system
LI Yu-ling1, CHEN Bin2, MA Wan-shan*1
1. College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China; 2. Zhengzhou Railway Vocational and Technology College, Zhengzhou 450052, China
Abstract：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 %.
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