Effects of Surface-Active Agents on Stability of Oil-In-Water Emulsions.
Coconut and palm-kernel oils are locally available vegetable oils used topically for cosmetic preparations. These have been formulated into oil-ill-water emulsions using different types of surface-active agents as emulsifiers and their emulsions have been found to compare favourably with those of liquid paraffin, a mineral oil. These vegetable oils produced emulsions of smaller droplet sizes than emulsion of liquid paraffin. The type of emulsifier used was observed to influence the properties of emulsions of these oils in water. The emulsifier employed consisted of Manoxol OT (anionic), Cetrimide (cationic) and Tween 40 (non-ionic). Emulsions of the vegetable oils were more stable than emulsions of liquid paraffin when ionic surfactants were used as the emulsifier. On increasing the concentration of emulsifier used from 2.5% through 7.5%w/w, the stability of the resulting emulsions increased. The initial distribution of the emulsifier in either of the two phases constituting the emulsion was found to play a very minor role on emulsion stability. The physico-chemical properties of the oils and their effects on properties of the emulsions produced by these oils are also presented in this study.