(400b) Advective Flow in Bicontinuous Interfacially Jammed Emulsion Gels (bijels) for Continuously Operated Liquid-Liquid Extraction

Bicontinuous interfacially jammed emulsion gels (bijels) have been predicted for use as continuously operated cross-flow reactors for chemical reactions between immiscible reactants. Here we introduce a major step to realize this promise: Advective flow in bijels for continuous liquid-liquid extraction. Bijels are formed by a modified version of solvent transfer induced phase separation (STrIPS), termed inverted STrIPS. A nanoparticle doped ternary liquid mixture is extruded into oil to generate particle stabilized bicontinuous fibers composed of water channels interpenetrated by oil channels. Confocal laser scanning microscopy reveals that the channel size can be reduced to a few hundred nanometers by carefully tuning the ternary phase equilibrium and the nanoparticle surface modification. The fibers are 3D printed and assembled into a microfluidic cross-flow reactor with their ends connected to in- and outlets. Application of a voltage across the length of the fibers facilitates electroosmotic flow within the aqueous domains. Simultaneously, a pressure gradient is employed for advective flow of the oil. Continuous extraction of a fluorescent dye from water to oil is studied in 3-dimensions by confocal laser scanning microscopy, revealing the effect of the interface organization on the mass transfer efficiency. We report our research as a major step towards using bijels as media for multiphasic processes with potential applications in Pickering interfacial catalysis and as cross-flow microreactors.