Solubilization of water by dialkyl sodium sulfosuccinates in hydrocarbon solutions

Abstract

The apparent solubilization of water in hydrocarbon solvents by the addition of 0.1% to 2.0% w/w di-(2-ethylhexyl) sodium sulfosuccinate (AOT) has been studied. In n-octane and n-decane, transitions of clear-turbid-clear-turbid were observed with increasing water content, whereas in dodecane, tetradecane, hexadecane, cyclohexane, and toluene only one clear-turbid transition was seen. Separation of the first turbid region in n-octane and n-decane gave two clear phases. Direct analysis indicates a hydrocarbon phase containing surfactant-solubilized water and an aqueous phase containing some surfactant. Increasing amounts of water partition between these phases until a second clear region appears. Separation of phases in the second turbid region in n-octane and n-decane and in the turbid region of the other solvents produces a pure hydrocarbon phase and a phase containing a complex aggregate of AOT/water/hydrocarbon. Solubilization of water in n-octane solutions of di-(n-octyl) sodium sulfosuccinate and di-(n-hexyl) sodium sulfosuccinate is greatly reduced when compared to AOT. This suggests a significant effect due to the ethyl side chain in the AOT molecule.