Characterization of liquid–liquid mass transfer performance in a capillary microreactor system

Abstract

Liquid–liquid mass transfer performance in a capillary microreactor system was studied with an improved experimental method. Proper sampling modes were chosen to eliminate the effect of the sampling zone on the mass transfer characterization in capillary microreactor systems. The overall volumetric mass transfer coefficients in the T‐micromixer and the capillary microreactor system were found to smoothly increase and then significantly increase with increasing the Reynolds number of two immiscible liquid phases. Other factors such as the inlet mode and inner diameter of T‐micromixer, the capillary length, and the volumetric flux ratio of the aqueous phase to the organic phase affected the mass transfer performance in the T‐micromixer and the capillary microreactor system. Furthermore, the contribution of the mass transfer in the T‐micromixer zone to the capillary microreactor system was found to be in a range of 34–78% under the involved experimental conditions, which was emphasized in the proposed empirical correlations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1106–1116, 2018

Intensification of liquid–liquid two‐phase mass transfer in a capillary microreactor system

“…As compared with the T‐micromixer without modifications (ET‐1 and ET‐2), much stronger interfacial disturbance, larger effective interfacial area and higher surface renewal rate could be obtained at the junction of the modified T‐micromixer with the effect of the jet flow induced by narrowing the micromixer inlet channels at medium to high Reynolds numbers ( Re M > 20 and Q total > 2 mL/min). These results again proved that the mass transfer can be enhanced by increasing kinetic energy of the two immiscible liquid phases in the micromixer zone in the capillary microreactor system …”

“…The parallel flow with smooth or wavy interface and the chaotic thin striations flow were formed in the T‐micromixer zone, and they, respectively, evolved to the slug flow, the parallel flow with smooth interface and the annular flow in the following capillary zone in the original capillary microreactor system (ET‐1) at involved Reynolds numbers of the two immiscible liquid phases . Moreover, the contribution of the mass transfer in the T‐micromixer zone to the capillary microreactor system occupies a large percentage . The purpose of narrowing the T‐micromixer inlet channels was to achieve higher superficial velocities, which was beneficial for the collision between the aqueous and organic phases inside the junction of the T‐micromixer.…”

“…Since both the applied T‐micromixers and the capillaries were hydrophobic, the organic phase tended to be the continuous phase, and the aqueous phase was the dispersed phase in the mass transfer process. The mixed stream from the capillary microreactor system or the T‐micromixer was collected with different sampling time and then separated as two immiscible liquid phases according to the optimized time extrapolation method with the elimination of the effect of the sampling zone . The amount of succinic acid transferred from the organic phase into the aqueous phase was analyzed by titration with standard sodium hydroxide solution ([NaOH] = 0.005 mol/L) using an automatic potentiometric titrator (INESA ZDJ‐5, China).…”

“…Such microreactor systems are modular, flexible, inexpensive and can be prepared rapidly from commercially available parts . Recently, we proposed an experimental method to precisely characterize the liquid–liquid mass transfer performance in capillary microreactor systems with the elimination of end effect, and the contribution of the mass transfer in the T‐micromixer zone to the capillary microreactor system was found to be in the range of 34–78% …”

Microfluidic synthesis of ultrasmall Co nanoparticles over reduced graphene oxide and their catalytic properties

“…Because the characteristic channel size of a microreactor is usually in the submillimeter scale, the surface to volume ratio is significantly increased, and the diffusion distance of the reacting agents is shortened to a large extent compared to the conventional batch reactor. Therefore, microreactors can achieve very fast mixing and mass/heat transfer, along with precise control over the reaction parameters . In addition, the continuous operation mode of the microreactor can avoid batch‐to‐batch variations, and the numbering‐up strategy adopted with microreactors facilitates the scale‐up from laboratory to industrial sites.…”