A comparative study on emulsification in the presence of a nanoclay (Pickering emulsion) or a surfactant using high intensity mixing

The study explored the potential of using a nanoclay, Laponite RD, as a stabilizing agent in comparison to a surfactant, Tergitol TMN6, at dispersed phase volume fractions of 10–50% vol. An ultrasonicator was employed as an energy intensive device; covering a specific power input range of ∼ 36–52 W kg^{− 1}. In both cases, final dispersions obtained could be considered stable over the period of ageing tests for 3 months as comparable drop size distributions were obtained although there were some differences in the rheology at the highest dispersed phase concentration. Whilst surfactant stabilized emulsions were of Newtonian behavior, Pickering emulsions stabilized with the nanoclay exhibited non-Newtonian behavior, which may be a desirable feature of the final product- certainly one that requires attention in design and scale up. Kinetics of breakup studied through the evolution of the Sauter mean diameter prior to reaching an equilibrium value on the basis of energy density have shown the breakup process being faster with the Pickering emulsions although the equilibrium drop diameters were larger. Overall, with emulsions stabilized using a surfactant, Sauter mean drop diameters could be as low as 240 nm, regardless of the dispersed phase volume fraction, drop sizes were larger with Pickering emulsions which depended on the dispersed phase concentration.