Analysis of mass transfer in microreactors for stratified and drop flow configurations

A. Basauri, J. Gómez-Pastora, I.H. Karampelas, M. Fallanza, E. Bringas, I. Ortiz
University of Cantabria,

Keywords: mass transfer, microextraction, stratified flow, drop flow, CFD modeling, microfluidics


Micro-solvent extraction processes have substantially expanded lately in their scale and importance due to the several advantages that microfluidics exhibit. Consequently, miniaturized systems have known a broad range of potential applications to the recovery of high added-value compounds such as base metals, rare earths elements, radioisotopes and even organic compounds from natural substrates as bacteria, virus, and endotoxins. The aim of the present work is to provide a thorough analysis of a micro-solvent extraction process in order to contribute to the understanding and modeling of the involved phenomena in the design of micro-separation devices. To this end, the coupled influence of flow patterns and mass transport kinetics on the performance of the micro-extraction systems has been analyzed in a homogeneous system composed of aqueous phases and a heterogeneous system where the receptor phase contains Shellsol D-70 and Alamine 336. In this work, we present a CFD model that accounts for different flow patterns such as stratified and drop flow. The Eulerian model provides the performance of the micro-device in terms of target solute separation as function of the residence time along the device. For the experimental assessment of model predictions the separation of Cr (VI) anions from aqueous solutions has been selected. Model simulated results have been experimentally assessed by using aqueous solutions of hexavalent chromium as tracer. Extraction percentages of these two flow patterns were compared and, while stratified flow system achieved an extraction percentage of 25% and 85% for the homogenous and heterogeneous systems, respectively, the drop flow system generation successfully reached 75% of extraction due to the larger interfacial area between fluid phases.