The influence of colloids on the particle size and stability of O/W emulsions in the presence of nonionic surfactants

Abstract

The effect of the presence of colloids on formation, stability and particle size of n-undecane in water nanoemulsions prepared by the Emulsion Inversion Point (EIP) method using nonionic surfactants (Igepals) was studied. The influence of oil-to-water ratio, the HLB value and concentration of the surfactant on their physico-chemical characteristics was also investigated. The stability of emulsions was assessed from changes in the particle size and the particle size distribution as well as through visual assessment of their appearance. The results obtained show that the anticipated positive effect of the colloids on emulsion stability was not confirmed. Phase separation of these systems usually occurred soon after preparation or during a few days of their storage. The particle size of emulsions prepared in the presence of colloids was mostly bigger in comparison with emulsions where colloids were absent. Nevertheless, nanoemulsions with the particle size smaller than 200 nm were also obtained. The best long-term stability was observed in emulsions prepared at the HLB value of 11.5, oil content of 20 and 30 wt. % stored at 4 degrees C.