A Paper Chromatographic Study of Oily Soil Removal

Abstract

A paper chromatographic technique was used to study the physico-chemical effects of detergents for the removal of oily soils from fiber assemblies without mechanical and/or hydrodynamic forces. Using a cellulose filter paper as the fiber assembly for the fixed phase, the R_f' value of oleic acid (OA), oleyl alcohol (OL), squalene (SQ) or cholesterol (CH) as a model of oily soil has been studied in sodium dodecyl sulfate (SDS) solutions as a function of the concentration and temperature.
The R_f' value, a measure of the detergency began to increase at a co ncentration below the critical micelle concentration (cmc) of SDS, ca.1.5, 2.0, 2.5 or 4.0 mM for CH, OL, OA or SQ, respectively, and was larger for higher concentrations to give higher detergency. The SDS concentration necessary to increase the R_f' value to 1 was near the cmc, ca.7.0 mM for OA and OL, and 8.0 and 9.0 mM for CH and SQ, respectively. The higher the temperature, the lower was the SDS concentration needed to increase the R_f' value for OL.
Atlow concentra tions below the cmc, the removal of oily soil is governed by formation of a molecular complex between the oily molecule and SDS.