Recently, studies on technologies of efficiently capturing, transporting and storing carbon dioxide from off-gas streams in order to reduce greenhouse gas emissions have been actively conducted. At present, absorption processes that use wet absorbents are being widely used to separate and remove carbon dioxide from off-gas streams. In general absorption processes, absorbents such as amine-based compounds are used to absorb and separate carbon dioxide from off-gas streams. However, this absorption process has a disadvantage in that the amine-based compounds are expensive, and thus the costs of designing and operating an apparatus for separating carbon dioxide increase. In addition, the absorption process has problems in that the consumption of energy for regeneration of the absorbent is high and an apparatus for treating off-gas is corroded by the amine-based compound.