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Study of alcohol‐free microemulsion systems containing fatty acids as cosurfactants
Author(s) -
Lohateeraparp Prapas,
Wilairuengsuwan Pongtai,
Saiwan Chintana,
Sabatini David A.,
Harwell Jeffrey H.
Publication year - 2003
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-003-0243-8
Subject(s) - microemulsion , chemistry , fatty alcohol , hexane , fatty acid , carbon number , alcohol , sodium dodecyl sulfate , chromatography , salinity , carbon chain , alkane , pulmonary surfactant , organic chemistry , alkyl , hydrocarbon , biochemistry , ecology , biology
In this study, fatty acids with carbon chains ranging in length from 3 to 8 (propyl to octyl) were used in place of alcohols to form microemulsion systems. The microemulsion systems contained sodium dodecyl sulfate (SDS), hexane, fatty acid, water, and NaCl. The phase behavior of these systems was examined using salinity scans at 25°C. The results showed that propanoic and butanoic acids promoted the formation of clear isotropic microemulsions, whereas the other fatty acids promoted a gel formation. High hexane solubilization was obtained with all of the systems. The optimum solubilization parameter (SP * ) and optimum salinity ( S * ) decreased with increasing SDS concentration. With increasing fatty acid chain length, S * decreased but SP * increased. Conductivity meausrements showed that, during the salinity scan, the conductivity of the systems was relatively unchanged, gradually decreased, or was a maximum at a given value. Interfacial tension (IFT) measurements showed that ultralow IFT were realized between microemulsion and oil phases using the fatty acids and that SP * and IFT were inversely related. The results of this study confirm that microemulsions can be formulated without alcohols through replacement of the alcohols with the appropriate fatty acids.