Selective extraction of only unsaturated fatty acids from mixed oils using Internal Olefin Sulfonate (IOS)

In general, oils are highly soluble with each other and they are emulsified uniformly when a surfactant solution is added.  Hence, it is difficult to separate certain components from mixed oils.  Sebum is a mixture consisting of multiple oils and fats, and so on.  It is known that most of them are necessary to provide a barrier function to the skin, however, unsaturated fatty acids, which are generated by the decomposition of fats, are irritating to the skin.  Thus, selective removal of unsaturated fatty acids is expected to be good for the skin.  We found that the anionic surfactant, internal olefin sulfonate (IOS) makes it possible.

IOS is a sustainable surfactant of plant origin and exhibits a variety of specific properties due to its unique molecular structure.  It shows highly selective cleansing of unsaturated fatty acids in sebum.  The mechanism was revealed b[FK(紅1] y the visual observations of the oil/water interface, IR measurements and phase diagram analysis using oleic acid as a model for unsaturated fatty acids and triglycerides as a model for other sebum.

The oil/water interface observations showed that, the IOS aqueous solution/triglyceride interface does not change, whereas the IOS aqueous solution/oleic acid interface spontaneously deforms into a wavy shape.  This means that IOS specifically reacts with oleic acid.  From IR measurements, this might be driven by the intermolecular interaction due to hydrogen bonding between IOS and oleic acid.   Therefore, the key for the selective extraction is that it interacts with specific oils forming a highly fluid state that is easily removed.

In the presentation, we will also show the movies about the process of oleic acid extraction from mixed sebum.  This selective extraction has the potential to be applied to skin cleansing agent as a sebum selective cleansing technology.