Experimental and Theoretical Investigation on Surface Tension of Aqueous Surfactant Solutions

Equilibrium surface tension data for aqueous solutions of five surfactants are experimentally obtained using the pendant drop method. The additives employed are SDS, SLES, Triton X-305, HEC QP-300, and Carbopol 934. Measurements are obtained at temperature of 23°C.Adsorption isotherms with surface tension and concentration normalized by the respective values at critical micelle concentration are shown to represent the generalized behavior of surfactants. Results showed that surface tension decreases with increasing surfactant concentration for all samples.Using experimental data, four empirical and thermodynamic-based models; i.e., Malanovsky-Marsh (MM), Fu et al. (FLW), Li et al. (LWW) and Santos et al. (SFF) were evaluated for surface tension estimation, and it was found that MM method is the best method to correlate aqueous surfactant solution surface tension in this study..