Effect of methanol on the surface tension and viscosity of sodiumdodecyl sulfate (SDS) in aqueous medium at 298.15-323.15Â K

The surface tension and viscosity of sodiumdodecyl sulfate (SDS) in water and in 0.10, 0.20, 0.30 and 0.40 volume fractions of methanol in water at 298.15 K, 308.15 K, 318.15 K and 323.15 K are measured. The critical micelle concentrations (CMCs) of the solutions are determined from both the surface tension and viscosity. The critical micelle concentrations (CMC) of SDS in water as well as in methanol-water mixture are found to increase with increase in temperature. The CMC of SDS increases with the addition of methanol. The surface properties, such as the surface excess concentration Гmax, minimum surface area Amin, surface pressure πcmc and packing parameter P are calculated from the surface tension data. Viscosity B coefficients of the SDS solutions are calculated using the relative viscosity data.