Absorbent for desulfurization of combustion gas and method of treating combustion gas using the same

A method of treating combustion gas, comprising:

• a denitrification process of removing nitrogen compounds from the combustion gas;
• a collecting process of collecting the combustion gas obtained after removing the nitrogen compounds;
• a desulfurization process of removing minor components including sulfur-containing compounds from the collected combustion gas by using an absorbent for desulfurization;
• and
• a carbon dioxide capture process of capturing carbon dioxide using a carbon dioxide absorbent from the combustion gas obtained after removing the minor components,
• wherein the absorbent for desulfurization includes 15 to 16 wt % of potassium carbonate (K2CO3), 2 to 10 wt % of a promoting agent, and a balance amount of water, and wherein the promoting agent comprises hindered cyclic amine, hindered cyclic amine bicarbonate, or a combination thereof;
• obtaining a carbon dioxide absorbent byproduct after the carbon dioxide capture process is performed for a predetermined period.