金属离子对2-乙基己基膦酸单（2-乙基己基）酯钠盐微乳体系的影响研究

【作者】 曹小妹；

【导师】 魏万之；

【作者基本信息】 湖南大学 ， 应用化学， 2003， 硕士

【摘要】 2-乙基己基膦酸单（2-乙基己基）酯钠盐（NaEHEHP）是一种常见的金属萃取剂，能和油、水形成微乳体系。研究金属离子对该微乳体系的影响，对开发利用其制备超细颗粒具有重要的理论和实际应用价值。 本文首次研究了在不同溶剂下NaEHEHP形成W／O单相微乳液的趋势及不同金属离子(Na⁺、Mg²⁺、Cu²⁺、Co²⁺、Ni²⁺、Zn（2+）、Cr³⁺、Al³⁺)对其热力学函数-ΔG_c→i^o的影响。通过向固定浓度和体积的NaEHEHP／正辛烷溶液中加入正辛醇和金属盐水溶液的方法，测定了不同金属离子在W／O单相微乳液中的极限增溶分数φH₂O，其大小排列顺序为：Al³⁺＜Cr³⁺＜Cu²⁺＜Co²⁺＜Mg²⁺＜Ni²⁺＜Zn²⁺＜Na⁺。分析表明，影响水增溶的主要因素是NaEHEHP作为萃取剂与金属离子形成金属-萃取络合物，而不同金属-萃取络合物在微乳体系中的亲油性不同导致了上述结果。对Al³⁺、Cu²⁺、Co²⁺、Mg²⁺、Ni²⁺等金属离子在NaEHEHP／正辛烷微乳体系中的最大含盐量进行了比较研究，结果表明，最大含盐量的排列顺序为：Al³⁺＜Cu²⁺＜Co²⁺＜Mg²⁺＜Ni²⁺。该数据可以更为简便、直接的了解微乳液中的金属含量问题，为开发微乳液法制备超细颗粒方面的应用提供了依据。 本文率先研究了上述金属离子在NaEHEHP／正辛烷／正辛醇／金属盐水溶液微乳体系中的相行为影响。当金属离子的浓度增加时，体系发生了WinsorⅠ→Ⅲ→Ⅱ型相转变。在不同金属盐体系中，产生中相的金属盐浓度的范围（中相盐宽，ΔC）各不相同，按照中相盐宽大小的排列顺序为：Cr³⁺＜Co²⁺＜Mg²⁺＜Ni²⁺＜Cu²⁺＜Zn²⁺＜Al³⁺＜＜Na⁺。结果表明，金属离子的中相盐宽越小，体系中形成的金属萃取络合物亲油性越强，萃取剂对该金属的选择性越好。 本文还研究了助表面活性剂正辛醇对上述微乳体系相行为的影响，正辛醇含量增加，体系同样能发生WinsorⅠ→Ⅲ→Ⅱ型相转变。在不同金属盐体系中，微量正辛醇的加入能明显降低金属离子的中相盐宽，但不会改变中相盐宽的排列顺序。即正辛醇的加入能增强体系中所形成的金属萃取络合物的亲油性，但是不会改变该萃取剂对金属的选择性。更多还原

【Abstract】 As a familiar metal extracting agent, sodium 2-ethylhexyl 2-ethylhexylphosphinate can be used to form microemulsion with oil and water. Study the effect of metal ions in the microemulsion systems is of important for relative theory and practical application on the utilization of developing a method of microemulsion to prepare for nanometer metal grains.formation of a W/0 microemulsion consisting of sodium 2-ethylhexyl 2-ethylhexylphosphinate(NaEHEHP) with different solvents and effects of different metal ions such as (Na+, Mg2+, Cu2+, Co2+, Ni2+, Zn2+, Cr3+, A13+) onthe thermodynamics function -AG, were investigated respectively. Byto add in n-octanol and aqueous metal solution into a fixed concentration and volume of NaEHEHP/n-octane solution, the limiting fractions ofsolubilized water in the W/0 microemulsion of different metal ionswere determined respectively. Experiments indicated that the ofvarious metal ions investigated increases in the following order: Al3+ <Cr3+<Cu2+<Co2+<Mg2+<Ni2+<Zn2+<Na+. The major factor affecting the water solubilization is the formation of a metal-extractant complex consisting of NaEHEHP as an extracting agent and metal ions. The different hydrophobicity of the metal-extractant complex in microemulsion leads to the results above. The maximum salt contents of different metal ions such as (Mg2+, Cu2+, Co2+, Ni2+, A13+) in the NaEHEHP/n-octane solution have been compared and studied, The result shows the arrange in the following order is: Al3+<Cr3+<Cu2+<Co2+<Mg2+. The date can be used to solve the problem of the metal content in this microemusion system simply and directly. A gist will be offered on the application of developing a method of microemulsion to prepare for nanometer metal grains.This is one of the first studies to focus on the phase behavior ofvarious metal ions, as detailed above, in the microemulsion system, sodium 2-ethylhexyl 2-ethylhexyLphosphinate/n-octane/n-octanol/aqueous metal salt solution. The phase change of Winsor type I-III-II II in these systems can occur as the concentration of metal ions increases. In the systems containing different metal salts, the range of metal salt concentration where the middle phase is generated (salinity width of the middle phase, AC) is different. The metal ions studied can be arranged in the following order according to the salinity width of the middle phase as Cr3+<Co2+<Mg2+<Ni2+<Cu2+<Zn2+<Al3+<Na+. The result shows that the less of the salinity width of the middle phase, the stronger of the hydrophobicity of the different metal-extractant complex, and the better extraction selectivity of that metal.The effects of n-octanol as assistant surface-active-agent on the phase behavior in these said microemulsion systems have also been researched. As the content of n-octanol increased, the phase change of Winsor type I-III-II in these systems can be occurred alike. In the systems containing different metal salts, salinity width of the middle phase has been reduce obviously and the order of arrange has not been changed with addition of micro-n-octanol. As a matter of fact, hydrophobicity of the different metal-extractant complex can be boosted but the extraction selectivity of the different metal in this system can not be changed with addition of n-octanol.更多还原