Effects of emulsification process and surfactant type on properties of concentrated O/W emulsions

There are many studies of concentrated emulsions involving the preparation method and the choice of surfactants to achieve good emulsification and high stability. Usually, for high internal phase emulsions (HIPE), superior than 75 vol%, emulsification processes are time-consuming or require large energy (around 10,000 rpm). In terms of surfactant, those with high external phase solubility would be the most suitable. However, emulsification is affected by many parameters, including each step of preparation method and each substance added to the system, making this topic very complex. The main purpose of this project is to study the effect of different parameters on the emulsification, stability, and properties of concentrated oil-in-water O/W emulsions. The parameters are speed of stirring, time of homogenization, internal phase addition flow and volume fraction, type of surfactant, and addition of fatty alcohol. We produced concentrated emulsions with 3 different cationic surfactants, using a speed stirring of 1,200 rpm. Visual observation and zeta potential provided information about stabilization. Laser diffraction and optical microscopy were used to evaluate the droplet sizes. The results allowed to determine the critical parameters for emulsion's droplet size distribution and stabilization, what we expect to bring new perspectives for systems of concentrated emulsions.