Surfactants play an important role in many industries such as cosmetics, perfumes, medicines, and foods, as they are widely recognized due to the diversity of their structures and their analysis, and are responsible for the formation of O/W or W/O emulsions as reported in the literature. The current work presented an investigation on the physicochemical properties of sodium dodecyl sulfate (SDS) and its effect on the formation of sesame oil/ water microemulsion in the presence of lauryl alcohol (LA) as a cosurfactant using electrical conductivity and hydrodynamic viscosity measurements. It has been found that the critical micelle concentration (CMC) of SDS in the aqueous environment is 10.75 × 10-3 M, which is consistent with its literature value reported. It was observed that the CMC gradually decreases with increasing temperature. However, the variation in the degree of micelle ionization with temperature showed a maximum and minimum at 35 OC and 45 OC, respectively. The variation of Gibbs free energy of SDS micellization as a function of temperature. Indicated that the SDS micellization in aqueous media is a spontaneous process and is thermodynamically favorable. It was clearly noticed that the CMC of SDS goes on increasing with the addition of sesame oil. which was also reflected by a gradual drop in the relative viscosity as the oil % increases. This may be attributed to the fact that oil droplets undergo fractioning and then get emulsified in the hydrophobic cores of SDS micelles. Because of such emulsification, the size of SDS micelle increased, and consequently higher concentrations of SDS would be required to reach an equilibrium micellization with the further addition of oil as a disperse phase. The effectiveness of SDS on emulsification demonstrated the ability of SDS surface hypotension in the formation of Microemulsions. Accordingly, SDS can be used as a powerful emulsifying agent to minimize the surface tension in the water medium and produce Microemulsions that would have many promising future applications.

Keywords : Surfactants; Microemulsions; Sodium Dodecyl Sulfate; Sesame Oil; Lauryl Alcohol; CMC; Electrical Conductivity.