Studies on CO₂ Adsorption and Desorption Properties from Various Types of Iron Oxides (FeO, Fe₂O₃, and Fe₃O₄)

Various type iron oxides of FeO, Fe2O3, and Fe3O4 were used for carbon dioxide (CO2) capture at room temperature and pressure by studying its adsorption–desorption properties. Several interactions of carbonate species were detected on its surface. The morphology of carbonate formation shows different structures on FeO (grooves-like), Fe2O3 (fine sharp particles), and Fe3O4 (aggregated nanoparticles). CO2 chemisorption discovered a potential adsorbent of Fe2O3 with an adsorption capacity of 3.95 mgCO2/gadsorbent. The adsorption capacity increased up to 62.8% by using concentrated 99.9% CO2 for adsorption. At higher concentration of CO2 exposure, it partially turns to red color which indicated the less stable Fe3O4 was easily oxidized to Fe2O3 after CO2 regeneration with temperatures up to 500 °C. Hence, Fe2O3 possessed the highest basicity strength (1.26 cm3/g), and the adsorption capacity after four cycles was not significantly reduced by 8.6% indicating an effective chemical or physical adsorption in CO2 capture.