关键词: 微乳液, 2-乙基己基膦酸2-乙基己基酯, 溶剂萃取

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