磷酸三丁酯从氯化物介质中萃取Zn与Cd的机理研究

EXTRACTION OF Zn AND Cd FROM CHLORIDE SOLUTIONS BY TRI-n-BUTYL PHOSPHATE

研究了磷酸三丁酯(TBP)从氯化钠稀盐酸溶液中萃取Zn和Cd,用多种物理化学方法确定了萃合物的组成。实验结果表明,TBP从氯化钠的稀盐酸溶液中萃取Zn,Cd,其有机相络合物的形式分别可能为ZnCl_2·2TBP和CdCl_2·2TBP。对于Cd,在较低的酸度条件下,有机相中就出现氯镉酸(HCdCl_3)的共萃取,随着溶液酸度增加,有机相萃合物中H_2CdCl_4占主导地位。而对于Zn,只有当溶液酸度达到一定值时([HCl]>0.1mol/L),有机相萃合物中才出现氯锌酸(HZnCl_3)的形式。此外,对萃取机理及温度效应也进行了讨论。

Studies have been made on the extraction of Zn and Cd by TBP (tri-n-butyl phosphate) from diluent HCl solutions of NaCl. The experiments show thatthe species extracted from dilueat HCl solutions of NaCl appear to be predominatelyZnCl_2·2TBP and CdCl_2·2TBP. For Cd, at lower acidities, anionic complexes of thetype HCdCl_3 are also extracted. As the acidity is increased, the type H_2CdCl_4 ap-pears to be predominate complexes in organic phase. For Zn, the acido-complexes ofthe type HZnCl_3 appear in organic phase after the acidity of solutions reachs a cer-tain value ([HCl]>0.1 mol/L). Furthermore, the ultraviolet absorption spectra ofboth aqueous and organic phases have been studied, and the infrared spectra of theorganic phases have been examined. The extraction mechanism and temperaturedependence are also discussed.