Adsorption of Low-Level CO2 Using Modified Zeolites and Activated Carbon

To control the levels of indoor CO2 in public spaces, we investigated adsorption at room temperature onto zeolites and activated carbon (AC) modified by alkali and alkaline earth metals. A fixed-bed adsorption apparatus was used to obtain more information about the effects of impregnated cations. Cations impregnated into the supports had a significant influence on the adsorption of CO2. In particular, sorbents impregnated with Ca had the highest adsorption capacity. Moreover, modified zeolites (for all cations) had greater adsorption capacities than ACs, despite their smaller surface areas, because of the electrostatic interforces between zeolites. The presence of moisture in the mixed gas flow caused decreases in adsorption capacity. The results of the equations of Sips and Toth matched well with the CO2 adsorptions of the present test sorbents. The presence of cations induced heterogeneous interactions between CO2 and the sorbents.

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