Evaluation of porosity and pressure drop on kenaf-monoethanolamine (MEA) modified sorbent for carbon dioxide adsorption application

The increasing of carbon dioxide (CO₂) emission has become a major concern in averting the global warming effect. Prior to the established adsorption process in carbon capture and storage technology (CCS), the development towards potential bio-modified adsorbent had been extensively studied by impregnating monoethanolamine (MEA) on the bio-sorbent surface, as to increase the porosity of the raw sorbent towards enhancement in capturing CO₂. As been recognized by Kyoto Protocol, kenaf (Hibiscus Cannabinus L.) is an eco-friendly industrial organic material that could overcome global warming issues due to its distinctive properties such as low density, highly porous, renewable, cheaper, and abundantly available compared to other organic or commercial adsorbents. Thus, kenaf as bio-sorbent material was used in this study with chemical modification done to evaluate its properties enhancement for CO₂ adsorption enhancement. In the previous study, MEA has been proved as a good solvent to be impregnated into kenaf sorbent as it improved the adsorptive capacity by 16%. Therefore, this study focused on the evaluation on the porosity enhancement by impregnated MEA on kenaf sorbent at difference impregnated temperatures. The pressure drop across the modified sorbents using porosimeter was determined as to further evaluate on the porosity effect. Three different impregnation temperatures; 20, 27 and 40°C at 1:1 kenaf to MEA concentration ratio were evaluated. All samples were analyzed for the elemental composition to prove the successful of impregnated amine functional group (N-H). Through the porosimeter, it showed that the pressure drop across the modified kenaf-MEA had increased as higher temperature impregnated were used. The porosity of the modified sorbent evaluated had also increased proportionally to the pressure drop. The adsorbent experienced large pressure drop as more gas diffuses within the available void spaces in the kenaf sorbent. The enlargement of the porous media on the kenaf surface was due to the impregnated of amine functional group, thus increases the pore volume of the sorbent. This also agreed to the Boyle’s Law of Gas Expansion Method. From the study, it showed that the modified kenaf-MEA at 40°C impregnation temperature had the highest porosity of 58.6 with a pressure drop of 2.93 bar. This result indicated that the improvement of porosity was achieved by modification of kenaf sorbent at a high impregnated temperature.