Carbon Dioxide Capture in Sodium Carbonate Solution: Mass Transfer Kinetics and Dtac Surfactant Enhancement Mechanism

Abstract

Sodium carbonate solvent absorbent has been widely studied for CO2 reduction to deal with global warming because of its green, low cost, and non-corrosive advantages. However, in the application of sodium carbonate as an absorbent for CO2 capture, there is no unified cognition of the mass transfer process, which leads to the lack of guidance for the industrial large-scale process. Based on this, in this paper, we used a bubbling reactor combined with dissolved oxygen test method to measure its CO2 capture efficiency, volumetric mass transfer coefficient, and enhancement factor with multi-influence factors including oxygen concentration, carbon dioxide concentration, sodium carbonate concentration, absorber temperature, and absorber volume. The results showed that the sodium carbonate solution with 5 wt% concentration and 10 wt% concentration at 30 °C did not satisfy the pseudo first-order fast chemical reaction kinetics assumption. To improve CO2 absorption mass transfer rate, DTAC surfactant was introduced, and the results showed that the absorption performance was optimal at a concentration of 5 wt%, and the maximum efficiency was >95% after adding 0.05 g/L DTAC surfactant into the absorbing solution, which was improved by 119% compared with non-enhanced solvent, and the assumption of pseudo first order fast chemical reaction was satisfied. After the introduction of surfactant, the barrier effect decreased the liquid phase mass transfer coefficient, but the Marangoni effect happened in the 5 wt% concentration of sodium carbonate solution, which enhanced the liquid-phase mass-transfer coefficient.

Keywords: CO2 capture, DTAC surfactant, Sodium carbonate solution, Mass transfer kinetics, Chemical reaction