Synergistic behavior of SLS-OPE-10 binary mixtures at their CMC

Abstract

Abstract The micellation behaviour of mixtures of sodium lauryl sulphate (SLS) and octylphenol ethoxylate-10 (OPE-10) was investigated using tensiometry and dye solubilisation. The interaction parameters for the system were determined using Rubingh’s model for non-ideality and the adsorption parameters were calculated. The surfactant mixture was found to behave synergistically in terms of CMC reduction and dye solubilisation. Furthermore, the mixture appears to mimic the adsorption and micellation properties of OPE-10 more closely than SLS, regardless of composition. With this knowledge, and considering that OPE-10 is typically more expensive than SLS, the formulator can now use only a fraction of the required amount of OPE-10 for a given application (instead of using 100% OPE-10), resulting in high performance yet economical products. It was also found that the said mixture exhibits azeotropic behaviour at a certain fixed composition.