Studies on Removal of a Fatty Soil Mixture of Triglyceride and Fatty Acid. II.

Interaction between Fatty Acid Soil and Surfactant

Abstract

Effect of the interaction between fatty acid soils and surfactants on removal of a triglyceride soil from cotton fabrics was studied in relation to the interfacial tension in a liquid paraffin (Nujol)/water system. Triolein as a model triglyceride was mixed with equal amount of individual fatty acids such as lauric, myristic, palmitic, stearic, and oleic acid and the mixtures were applied to cotton fabrics from chloroform solution.
Triolein mixed with individual fatty acids was removed more easily than triolein alone in sodium dodecyl sulfate (SDS) solution. The effect of saturated fatty acids on removal of triolein increased slightly with increasing carbon chain length of fatty acids.
Further, the interfacial tension in the Nujol/SDS solution was lowered markedly by the addition of palmitic acid. From the calculation of the adsorbed amounts of palmitic acid and SDS at the Nujol/water interface by Gibbs' equation, the ratio of palmitic acid to SDS was approximately 1 : 2.
When the effect of the surfactants, SDS and sodium dodecylbenzene sulfonate (LAS), on the removal of triolein in the presence of palmitic acid was compared, SDS was more effective than LAS. Further, in the system of which oil phase contained palmitic acid, SDS lowered the interfacial tension more than LAS did.
From these results, it is concluded that the complex formation by the interaction between fatty acid and surfactant at the soil/solution interface facilitates the removal of triolein by emulsification.