二（2，4，4－三甲基戊基）膦酸萃取锌

STUDIES ON THE EXTRACTION OF ZINC(II)BY CYANEX272 I. EXTRACTION THERMODYNAMICS

研究了二（２，４，４－三甲基戊基）膦酸（ＣＹＡＮＥＸ２７２，ＨＡ）从硫酸介质中萃取锌（Ⅱ）的热力学，考察了磷酸三丁酯（ＴＢＰ）对萃取的影响。结果表明，ＣＹＡＮＥＸ２７２与锌形成ＺｎＡ２，ＺｎＡ２·ＨＡ和ＺｎＡ２·２ＨＡ三种配合物，相应萃取热焓△Ｈ°分别为－７５．５３、－５２．７１和－２９．８７ｋＪ．ｍｏｌ－１，依次相差约一个氢键的能量与反应中断裂氢键数目有关。ＴＢＰ与ＣＹＡＮＥＸ２７２萃取锌时生成协同配合物ＺｎＡ２·２ＨＡ·ＴＢＰ，系由分子缔合物２ＨＡ·ＴＢＰ与Ｚｎ（Ⅱ）直接配位产生，协同萃取反应平衡常数１５．８。同时还计算得到ＺＨＡ·ＴＢＰ的生成常数３１．７（３０３Ｋ）。

The extraction kinetics of zinc (Ⅱ) by for (2, 4, 4-trimethylpentyl) phosphinic acid (CYANEX272,HA)from sulfuric acid medium was investigated and the chemical reaction (in organic bulk phase near the interface)controlled mechanism was presented. From the observation for the influence of TBP on the extraction, it has been found TBP exhibits the obvious kinetic acceleration for the extrachon rate of Zn (Ⅱ) by CYANEX272. Thus it can be considered that the molecular associate compel of TBP and CYANEX272 participates directly in the kinetic process and the mass transfer in extraction is controlled by a chemcal reaction-in-organic bulk phase,which lead to the acceleration of the extraction rate. Such a kinetic synergistic process will be accompanied by the phenomenon of thermodynamic synergism inevitably.