Conductivity measurements show that there are 3 types of sub-regions (W/O, IZ and O/W) in the SDS/BuOH/n-C8H18/H2O microemulsion. Conduction behavior of the microemulsion is due mainly to the SDS anion in the W/O and Na+ ion in the O/W sub-regions, resp. In the bi-continuous region (IZ), both the SDS anion and Na+ make their contributions to conduction. Increasing surfactant content helps to form O/W microemulsion, but both increasing cosurfactant and initial oil content help to form W/O microemulsion.

Key words: WATER, BUTANOL, HIGHER ALKANE P, ANIONIC SURFACTANTS, ELECTRICAL CONDUCTIVITY, OCTANE P, SODIUM SULFATE, C12 COMPOUNDS, SOLUTION CHEMISTRY, PHASE DIAGRAM