Carbon dioxide capture capacity of sodium hydroxide aqueous solution

The present paper investigates the various features of NaOH aqueous solution when applied as an absorbent to capture carbon dioxide (CO2) emitted with relatively high concentration in the flue gas. The overall CO2 absorption reaction was carried out according to consecutive reaction steps that are generated in the order of Na2CO3 and NaHCO3. The reaction rate and capture efficiency were strongly dependent on the NaOH concentration in the Na2CO3 production range, but were constant in the NaHCO3 production step, irrespective of the NaOH concentration. The amount of CO2 absorbed in the solution was slightly less than the theoretical value, which was ascribed to the low trona production during the reaction and the consequent decrease in CO2 absorption in the NaOH solution. The mass ratio of absorbed CO2 that participated in the Na2CO3, NaHCO3, and trona production reactions was calculated to be 20:17:1, respectively.