The activation energy ΔE can indicate the strength of the interfacial membranes of microemulsion particles, so it could be used to discribe and discuss the stability of the formed microemulsion in extraction organic phase- Variations of activation energies with water content for microemulsions formed in the organic phase of saponated P507 (2-ethyl-hexylphosphonic acid mono-2-ethylhexyl ester )-alcohol (n-propanol, n-butanol, n-pentanol and n-hexanol )-heptane-water were determined by measurement of electric conductivity.The curves between ΔE and water content VH2o were given. It is found that ΔE of butanol system decreases slightly with the increase of water content, while that of pentanol and hexanol systems presents a maximum. It is also found that the activati0n energy increases with the increase of the length of alcohol chain. These results reveal that the longer the length of alcohol chain, the bigger the strength of the interfacial membranes of particles, and the more stable the microemulsion is. Based on the above results, hexanol or octanol was always used as co-surfactant in extraction process.
展开▼
