Influence of viscosity for oil-in-water and water-in-oil nanoemulsions production by SPG premix membrane emulsification

Abstract

Oil-in-water and water-in-oil nanoemulsions are interesting carriers for respectively oil soluble and water soluble actives. In this study, oil-in-water (O/W) and water-in-oil (W/O) nanoemulsions were prepared by premix membrane emulsification. A coarse emulsion (premix) was injected thanks to a high pressure pump through a Shirasu Porous Glass (SPG) membrane with pore size of 0.5μm in order to reduce and homogenize the droplet size. The effect of viscosities on the pressure and droplet size was investigated: the water phase viscosity by increasing glycerol concentration, the oil phase viscosity with mineral oils of different viscosities and the overall emulsion viscosity by increasing the dispersed phase content of the emulsion. The pressure required to break up the droplets inside the membrane pores ΔPdis did not depend on viscosities, while the pressures generated by the flows through the pipe ΔPpipe and the membrane ΔPflow were proportional to the viscosity of the overall emulsion. W/O nanoemulsions were more difficult to produce and to characterize but thanks to the original set-up working at pressures up to 65 bar and high flowrates, W/O mineral oil nanoemulsions were produced with mean droplets size around 600nm and flow rate of 50mL/min.