Marangoni effect in a falling film microreactor

Abstract

Mass transfer in some gas–liquid systems may be significantly enhanced by the Marangoni effect. In the case of a falling film microreactor (FFMR) for gas–liquid reactions, the question whether the interfacial tension driven cells would develop in the limited space of a microchannel remains unsolved. One way of approaching this problem is to measure the mass transfer rate in a microreactor using a system known to exhibit the Marangoni effect in the macroscale, and to compare this rate with the value determined for the analogous process without this effect. Gas–liquid mass transfer in a FFMR with 29 microchannels (0.6 mm width each) was investigated. CO 2 was absorbed from a CO 2/N 2 gaseous mixture into an aqueous solution of NaOH, and the liquid side mass transfer coefficient as well as the gas side mass transfer coefficient were measured. Then the possibility of appearance of the Marangoni effect was investigated using aqueous monoethanolamine (MEA) solution. The existence of the cellular convection was observed. The enhancement of the overall rate of the mass transfer depends on both gas and amine concentrations.