Effect of surfactant mixtures on the stability of emulsions

Abstract

The emulsifying effect of individual surfactants of sodium dodecyl sulfate and Neonol AF9-6
and their mixtures were studied. The isotherms of surface tensions of water solutions of individual surfactants
were studied. Emulsions stability was evaluated by the phase separation time. It was found that solutions of
individual surfactants do not contribute to the formation of stable emulsions. The mixtures of anionic surfactant
NaDDS with the more hydrophobic nonionic surfactant Neonol AF 9-6 are more effective in preparation of
water-hexane emulsion and their synergetic action was shown. It was found that emulsions of the direct type are
formed at stabilizing with sodium dodecyl sulfate and Neonol AF 9-6 surfactant mixtures. The type of emulsions
was determined using a laboratory optical microscope after adding water and oil-soluble dyes – methyl orange
and Sudan IV. It was found that the most effective is a mixture of Neonol AF 9-6 with sodium dodecyl sulfate
taken in a ratio of 3:1 (wt.). At the total concentration of the surfactant mixture in the aqueous phase of 0.04%
and the volume ratio of water-hexane 1: 3, it was possible to obtain a highly concentrated stable direct emulsion.