Assessment of CO₂ Adsorption Capacity under Moderate Pressure Range on Activated Carbon Produced from Coconut Endocarp

Abstract

In this study, we prepared activated carbon using coconut residue (Cocos nucifera L.) and evaluate the potential use of this activated carbon for capture and storage of carbon dioxide (CO 2). Regeneration tests indicated that the activated carbon has a good regenerative capacity and maypotentially be used in CO 2 adsorption systems. For example, the ability of the activated carbon to capture and then release CO 2 is not significantly affected even after three consecutive adsorption/desorption cycles, regardless of the temperature tested (either 125, 150 or 180°C). Kinetic studies revealed that the time required for total saturation of the activated carbon was 25 min for the pressure range investigated (0.14-0.34 MPa). This ability to retain considerable amounts of CO 2 quickly under low pressures is likely due to the presence of microporous at the surface of this adsorbent, as suggested by reports in the literature and the morphological features of the activated carbon presented here. In addition, equilibrium studies using the Langmuir and Freundlich isotherms showed that the activated carbon has a maximum adsorption capacity of 76.03 mg gG 1 at 15°C. This adsorption capacity decreases with temperature increase, reaching 58.84 mg gG 1 at 35°C. Similar behavior has been observed for other absorbents and is expected for adsorption processes due to the exothermic nature of these processes. In summary, the results indicated that the activated carbon produced with coconut residue has great potential as a CO 2 absorbent.