Microemulsion Formation and Detergency with Oily Soils:III.Performance and Mechanisms

摘要

The objective of this study was to investigate the correlation between oily soil removal efficiency and low oil-water interfacial tension (IFT) generated by microemulsion formation.A mixture of sodium dioctyl sulfosuccinate,alkyl diphenyl oxide disulfonate,and sorbitan monooleate was selected as a detergent formulation to evaluate detergency performance for two highly hydrophobic oils:hexadecane and motor oil.The maximum detergency corresponds to formation of a Winsor Type III microemulsion as well as to the supersolu-bilization region,which is a Winsor Type I microemulsion close to the Winsor Type III region.In addition,the oil removal in the rinse step is almost as high as that in the wash step for both regions.We propose the following mechanism to explain these results:During the wash step,the contact angle of the oil on the fabric surface is progressively increased,resulting in the detachment of the oil droplets.However,owing to the very low IFT,the spreading effect is dominant,thereby causing incomplete oil removal.During the subsequent rinse step,the IFT increases,passing through a composition at which the rollup mechanism causes additional oil removal.These results demonstrate that microemulsion formation and the resulting IFT reduction are important mechanisms in oily soil detergency.