Abstract: The activation energy can indicate the strength ofthe interfacial membranes of microemulsion particles, so it would beused to describe and discuss the stability of the formed microemulsionin extraction organic phase. Variations of activation energies with water contents for microemulsions formed in the organic phase of saponified P507(2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester)-alcohol(n-propanol, n-butanol, n-pentanol and n-hexanol)-heptane-waterwere determined by measurement of electric conductivity. The curves between activation energy and water content V_H2O were given. It is found thatactivation energy of butanol system decreases slightly with the increase of watercontent, while that of pentanol and hexanol systems present a maximum. It is also found that the activation energy increases with the increase of the length of alcohol chain. These results evident that the longer length of alcohol chain, the bigger strength of the interfacial membranes of particles, and more stability of microemulsion. Based on the above results, hexanol or octanol always were used as co-surfactant in extraction process.

Key words: microemulsion, 2-ethylhexyl phosphoric acid mono-2-ethyhexylester, extraction chemistry

摘要： 采用测定微乳液电导的方法，求得P507(K)-醇-正庚烷-水萃取有机相中，在含有不同的醇(正丙醇-正己醇)和不同量水时，形成微乳液的活化能ΔE，并通过它来讨论萃取有机相中形成微乳液的稳定性。实验结果表明，醇的碳链越长，活化能ΔE越大，形成的微乳液也越稳定，有利于萃取。因此在实际萃取体系中，常通过加入正己醇、正辛醇等长链脂肪醇作辅助溶剂，以避免发生乳化和形成第3相。

关键词: 微乳液, 2-乙基己基膦酸2-乙基己基酯, 溶剂萃取