氯化钠-硫氰酸铵-正丙醇-水体系中铁(Ⅲ)的析相萃取分离和富集研究

Study on the phase separation extraction and enrichment of iron(Ⅲ) in sodium chloride-ammonium thiocyanate-normal propyl alcohol-water system

研究了氯化钠-硫氰酸铵-正丙醇-水体系析相萃取分离和富集铁的行为及铁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,Fe(Ⅲ)和NH4SCN生成的[Fe(SCN)4～6][(4～6)-3]-与质子化正丙醇C3H7OH2+形成的缔合物[Fe(SCN)4-6][C3H7OH2]1-3能被正丙醇相完全萃取。当溶液pH值为3,正丙醇的体积分数、NH4SCN溶液的浓度和氯化钠溶液的质量浓度分别为30%,7.0×10-2mol/L和0.2 g/mL时,Fe(Ⅲ)的萃取率达到97.5%以上,而W(Ⅵ),Ag(Ⅰ),Ce(Ⅲ),Cr(Ⅲ),Mn(Ⅱ),Cd(Ⅱ),Al(Ⅲ),Ni(Ⅱ),Ga(Ⅲ)和Mg(Ⅱ)基本不被萃取,实现了Fe(Ⅲ)与上述金属离子的分离。对合成水样和镍铬铝合金中Fe(Ⅲ)进行分离和测定,结果满意。该萃取体系可以用作微量铁的分离和富集,在分析中具有实用价值。

The phase separation extraction and enrichment behaviour of iron（Ⅲ） in sodium chloride-ammonium thiocyanate-normal propyl alcohol-water system,and the separation conditions of iron from some metal ions were studied.The results showed that,the sodium chloride could separate the normal propyl alcohol aqueous solution into two phases.In this process,the [Fe（SCN）4～6][（4-6）-3]-formed from Fe（Ⅲ） and NH4SCN could react with protonized normal propyl alcohol（C3H7OH2＋） to form complex [Fe（SCN）4-6][ C3H7OH2]1-3,which could be completely extracted by normal propyl alcohol phase.The extraction rate of Fe（Ⅲ） was above 97.5 % under the follow conditions：the pH of solution was 3,the volume fraction of normal propyl alcohol was 30 %,the concentration of NH4SCN solution was 7.0×10-2 mol/L,and the mass concentration of sodium chloride solution was 0.2 g/mL.Meanwhile,W（Ⅵ）,Ag（I）,Ce（Ⅲ）,Cr（Ⅲ）,Mn（Ⅱ）,Cd（Ⅱ）,Al（Ⅱ）,Ni（Ⅱ）,Ga（Ⅱ） and Mg（Ⅱ） could not be extracted,realizing the separation of Fe（Ⅱ） from these metal ions.Fe（Ⅲ） in synthetic water samples and nickel-chromium-aluminium alloy was separated and determined,and the results were satisfactory.This extraction system could be used in the separation and enrichment of trace iron,and it had practical value in analysis.