the absorption of carbon dioxide in an alkaline solution with crystallization has also been adopted to explore the removal of carbon dioxide from waste gas (Chen et al., 2008). This approach, with the production of carbonate by means of reactive crystallization, has been found to be effective. In order to remove of CO2 gas, several scrubbers were utilized, such as sieve tray column, packed bed column, rotating packed bed and bubble column. Therefore, how to choose an excellent scrubber becomes significant in the removal of CO2 gas from flue gas. The performances of the scrubbers were always estimated by using overall mass-transfer coefficient. Due to this, they found packed bed with structured packing (Aroonwilas & Tontiwachwuthiku, 19 )gives a higher overall mass-transfer coefficient as compared with other scrubbers. On the other hand, Chen et al. (2008) found that the performance of scrubber could be estimated by using scrubbing factor, a definition of removal of 1 mole CO2 gas per mole of absorbent and per liter of scrubber. In this manner, a bubble-column scrubber is the first choice.