Hydrodynamic characterization of continuous flow of Pickering droplets with solid nanoparticles in microchannel reactors

Abstract

In this work, a method based on Pickering emulsion systems (PES) was proposed to manipulate multiphase processes containing solid particles in microchannels without adhesion and/or accumulation. The flow hydrodynamics of PES in a microchannel were systematically characterized. For comparison, a suspension system (SS, ethyl acetate with suspended SiO2 nanoparticles-water) and a viscous fluid system (VFS, ethyl acetate with methyl-silicone oil–water) were examined. It was found liquid–liquid two-phase characteristics of PES, SS and VFS around T-junction within the main microchannel depended on surface hydrophobicity of stabilizing SiO2 nanoparticles, amount of SiO2 particles added, viscosity and flow rate. Four flow patterns were observed under these operating conditions for PES and VFS, where superficial velocity was the key factor affecting the flow patterns transition. Finally, a scaling law of the droplet size was established as a function of Qd/Qc, μd/μc and Ca.