Propionic acid extraction in a microfluidic system: simultaneous effects of channel diameter and fluid flow rate on the flow regime and mass transfer

In this work, extraction of propionic acid from the aqueous phase to the organic phase (1-octanol) was performed in T-junction microchannels and effects of channel diameter and fluid flow rate on the mass transfer characteristics were investigated. The two-phase flow patterns in studied microchannels with 0.4 and 0.8 mm diameters were observed. Weber ‎ number and surface-to-volume ratio were calculated for evaluating flow patterns. Moreover, the effect of volumetric flow rates on the extraction ‎efficiency, volumetric mass transfer coefficient, and pressure drop was examined. Results showed that the pressure drop in the microchannel with 0.4 mm diameter is 2-2.7 times higher than that in the microchannel with 0.8 mm diameter. In both microchannels, with increase in flow rate, the extraction ‎efficiency first increases and then decreases. In addition, at high flow rates (2.4, 4.5 and 6 mL/min), the extraction ‎efficiency in the microchannel with 0.8 mm diameter increased up to the range of 7-14.9 % compared with that in the microchannel with 0.4 mm diameter.