화학공학소재연구정보센터
Chemical Engineering Journal, Vol.307, 143-149, 2017
Droplet-based liquid-liquid extraction inside a porous capillary
Microfluidic operation of liquid-liquid extraction presents the advantage of very short molecular diffusion distances. This enables improved mass transfer under very controlled conditions. For a successful application of an extraction process in a microfluidic environment three operation steps are required: (I) creation of the interface between both liquids in the form of droplets or slugs, (II) the extraction itself, and (III) the efficient separation of both phases for further downstream processing. The last step still poses a challenge since gravity is ineffective as driving force for phase separation in the sub-millimeter scale. Here we present a novel continuous approach that combines all these stages in a new capillary membrane configuration. The porous membrane is split into two compartments for (a) droplet formation based on hollow-fiber emulsification and (b) phase separation by forced coalescence. The method is demonstrated for the extraction of acetic acid from paraffin oil to water as model system. We also show that it is even possible to invert the phases at the phase separation step by using a second membrane with opposite wetting properties. Finally, the possibility of scale-up by parallelization is proved with a three-fiber device that yields comparable results to the single fiber device. This method establishes a new continuous microscale liquid-liquid extraction in an inexpensive and very simple device design. (C) 2016 Elsevier B.V. All rights reserved.