The mixed surfactant system of linear alkylbenzene sulfonate and alpha olefin sulfonate

Physicochemical and detergency studies on the mixed surfactant system of linear alkylbenzene sulfonate‐sodium salt (LABS) and alpha olefin sulfonate‐sodium salt (AOS) have been carried out. The binary surfactant system exhibits minima in the surface tension and in the critical micelle concentration when the two surfactants are present in the ratio 80:20, indicating synergism in the mixed monolayer and in mixed micelles at this proportion of the two surfactants. The mixed micelles improve hard‐water tolerance of LABS and reduce the loss of LABS via Ca(LABS) 2 precipitation. Addition of AOS to LABS improves its lime soap dispersion properties. The effect is highly significant when AOS is present at the 20% level in the mixed surfactant system. A synergistic mixture of the two surfactants, when used in phosphate‐free, carbonate‐built detergent product formulation, exhibits superior detergency, low ash deposit and better stainremoving ability when compared to products containing LABS as the sole active surfactant.