Abstract: The aggregation behaviour of mixed surfactants, sodium bis(2-ethylhexyl)sulfosuccinate and Brij30, in n-heptane has been investigated by iodine spectrometric method. The results showed that the CMC of the mixed surfactants firstly decreased and then increased with the increase of the proportion of nonionic surfactant Brij30 due to electric interaction and geometry of the surfactants. The water solubilization investigation indicated that at lower surfactant concentration the solubilizing capacity of the mixed reverse micelles firstly increased and then decreased with the increase of the proportion of Brij30. The difference of CMC values determined by iodine spectrometric method and water solubilization has been discussed.

Key words: mixed surfactant, apolar solvent, aggregation behaviour, iodine spetrometric method, water solubilization, critical micelle concentration