Mass Transfer Characteristics of CO2 and Blended Aqueous Solutions of [C2OHmim][Lys]/MDEA in a Microchannel

In this paper, the two-phase flow and mass transfer process of CO2 and [C2OHmim][Lys]/MDEA mixed aqueous solution in a T-shaped microchannel were investigated systematically. By using a high-speed camera connected to a computer, the two-phase flow patterns were recorded online, including the Taylor flow and a small amount of Taylor-bubbly flow. And the effects of ionic liquid concentration and two-phase flow ratio (QG/QL) on bubble length, specific surface area, gas holdup, and mass transfer coefficient were studied experimentally. The results indicate that the blended solution of [C2OHmim][Lys]/MDEA could significantly enhance two-phase mass transfer compared to single N-methyldiethanolamine aqueous solution. The reaction mechanism between CO2 and ionic liquid/amine mixed aqueous solution was also analyzed. On the basis of experimental data, some new correlations for predicting the bubble initial length and the volumetric mass transfer coefficient were proposed, which matched well with the experimental data. This work is helpful to provide new ideas for the design of CO2 absorbents and further improve the data of gas–liquid mass transfer in microchannels.