Kinetics of formation of oil-in-water emulsions using in situ rheo-optical measurements

The kinetics of mechanical emulsification in vane geometry was investigated using an original rheo-optic device. Hexadecane-in-water micronic emulsions were prepared using a nonionic polymeric surfactant (Brij700®) as stabilizer. The viscosity of aqueous phase was adjusted using a commercial viscosifier (Emkarox®) which ensured Newtonian behavior to the continuous phase. The influences of two variables (rotational speed and oil volume fraction) on the kinetics of droplet fragmentation were examined in detail. Rotational speed was varied between 50 and 100 rad s−1 and had a strong effect on the kinetics of emulsion formation which was discussed on the basis of droplet fragmentation by shear forces. On the contrary, oil volume fraction (between 20 and 60% v/v) showed no marked effect, which appeared as an important result for scale-up considerations. A theoretical description of fragmentation mechanism was proposed and experimental results were compared to calculated values. © 2014 American Institute of Chemical Engineers AIChE J, 61: 277–284, 2015