Keywords: CO2 capture; adsorption kinetics; activated carbon; bismuth(III) oxide

Abstract

Bismuth(III) oxide (Bi2O3)-impregnated activated carbon (AC) composites were synthesized and prepared at different Bi2O3 loading. Adsorption capacities of the adsorbents were determined at varying adsorption temperatures by using thermogravimetric analysis (TGA). CO2 regeneration was successfully performed at 400°C, indicating the adsorbents were feasible with CO2 adsorption and desorption processed. 0.1Bi/AC was shown as the most efficient adsorbent at optimum adsorption temperature of 30°C with CO2 adsorption capacity of 58.71 mg CO2/g adsorbent. Although the BET surface area of 0.1Bi/AC was reduced (783.25 m2/g) compared to AC only, the Bi2O3 loading noticeably enhanced CO2 chemisorption due to the affinity to attract CO2. The adsorption kinetics indicated that chemisorption dominated the adsorption process as the data fitted well in the pseudo-second-order kinetic model. The stability of CO2 capture capacity was consistent over 5 cycles, with slightly higher than AC only, ascribed to the chemical adsorption by interactions of carbonate species with Bi2O3 besides the physisorption on AC. These features exhibited a potential for large scale applications of the adsorbent, which favored ambient conditions for CO2 adsorption and feasible desorption process.