Dispersal of nano-droplets in the water column by bursting bubbles in a liquid-liquid interface
Jie Feng (Princeton University), matthieu Roche (), daniele Vigolo ( Institute for Chemical and Bioengineering, ETH), Luben Arnaudov (Unilever), Simeon Stoyanov (), Howard Stone (Princeton University)
Complex Fluids: Suspensions, Emulsions, and Gels
Tue 4:20 - 5:40
Barus-Holley 160
The bursting of bubbles at interfaces is important in mass and energy transport in many problems in physics, chemistry and engineering. Here we show that the bursting of bubbles at a complex interface made of air, oil and an aqueous solution of surfactants results in the dispersal of droplets of oil in the bulk of the surfactant solution with sizes ranging from several tens of nanometers up to a few hundred nanometers depending on the oil used. Using high-speed photography to visualize the bottom surface of the bursting bubble, we show that a spray consisting of small droplets is ejected from the boundary of the collapsing bubble cavity into water. Although the size distribution of this spray seems broad, a characterization of the liquid sample after a few days of bubbling shows that the size distribution of the dispersed objects in the water column is centered around a value ranging between 80 and 500 nm, with near monodispersity. We provide experimental evidence that the size of these droplets is set not by the hydrodynamics of bubble bursting but rather by the interaction between oil molecules and surfactant molecules. Moreover, our system can be applied for the production of nano-emulsions in industry with an energy efficiency which is one order of magnitude better than that of conventional techniques, such as high pressure homogenizers and microfluidic methods. The nano-emulsions can be also used as a template for nanoparticles generation.