Studies on Removal Mechanism of Oily Soil Mixtures Consisting of Binary Systems of Triglyceride and Fatty Acid or Fatty Alcohol

Abstract

The removal mechanism of oily soils containing polar components such as fatty acids and fatty alcohols from fabrics in surfactant solutions was studied. Triolein as a model oily soil was mixed with oleic acid and oleyl alcohol in equal amounts and the mixtures thus obtained were applied to cotton and polyester fabrics.The surfactants used were dodecyl sulfate (SDS), the anionic type and dodecyl octa (oxyethylene) ether (C12E8), the nonionic type. The amounts of triolein and polar oils adhering to the fabrics were determined by the TLC-FID method following the extraction with ethyl ether.Triolein mixed with a polar oil was removed much more easily than when alone in either SDS or C12E8 solutions regardless of the type of fabric.The removal mechanism of triolein containing a polar oil in both surfactant systems is considered to be the following : In an SDS solution, the interaction between the polar oil and SDS at the oil/solution interface caused the interfacial tension to drop markedly, thus facilitating the removal of triolein by emulsification. In a C12E8 solution, the polar oil is solubilized highly in micelle formed by the surfactant promoting the removal of triolein by solubilization.On comparing the effects of the two polar oils for the removal of triolein in SDS solution, the presence of oleyl alcohol was more noted to be effective than that of oleic acid. This may possibly be due to the difference in the extent of interaction between SDS and oleic acid and oleyl alcohol.