油酸钠微乳液体系的结构参数和电导行为研究

Studies on the structural parameters and conductivity behavior of sodium oleate microemulsion system

本文用稀释法测定了油酸钠/醇/正庚烷/水四组分W/O型微乳液体系的结构参数:水内核半径Rw,颗粒有效半径Re,界面层厚度L,平均聚集数N,颗粒总数Nd,分散相总界面积Ad等结构参数和醇从连续相转移到界面的自由能△Goc-i。结果表明微乳液水内核半径Rw大小在纳米尺度;随含水量的增加,水内核半径Rw直线增加,而醇转移的界面自由能-△Goc-i减小,在含水量较低时微乳液的稳定性较强。对助表面活性剂的种类、内水相盐度变化对油酸钠微乳液电导率的影响进行了考察,结果表明使用正丁醇时形成电导渗滤体系,而使用正戊醇、异戊醇和正己醇时形成的是非渗滤体系;内水相中加入Na NO3对电导渗滤有抑制作用。醇碳链长度增加及适当的盐度有利于微乳液体系的稳定。

The structural parameters of sodium oleate / alcohol / heptane / water microemulsion system,inner water radius Rw,effective radium Re,length of interface L,average aggregation number N,total number of particles Nd,total interfacial area of dispersed phase Adand the change of standard free energy △G^oc-i for the alcohol transferring from continuous phase to interface membranes were calculated based on dilution method.It＇s found that the Rwwas in nanoscale,and with the increase of water uptake of microemulsion,Rwincreased linearly,-△G^oc-idecreased,which indicates that the microemulsion will be more stable with less water uptake.The variations of electric conductivity of microemulsion with alcohol species and salinity of internal water were determined.The conductance percolation was found for butanol as cosurfactant,but not for hexanol or pentanol.Addition of Na NO3 in internal water phase delayed the conductivity percolation for butanol as cosurfactant.This maybe indicate that the microemulsion will be more stable with the increase of carbon atom number of alcohol and the addition of proper amount of salt in internal water phase.