Woody Biomass-Derived Biochar Decorated with Vanadium Oxide as a Potential Adsorbent for CO₂ Capture

This study examines the production of metallized biochar as a cost-effective and sustainable adsorbent with a high carbon dioxide (CO₂) uptake at ambient temperature. Leucaena wood (LW)-derived biochar was prepared at various pyrolysis temperatures (500, 700, and 900 °C) for 90 min. Among all, highly microporous LW biochar, pyrolyzed at 900 °C, showed the highest CO₂ adsorption capacity of 52.18 mg/g at 30 °C, 1 bar This biochar was further impregnated with ammonium metavanadate solution at different concentrations (1, 3, 4, 5 and 8 wt%) and then heated at 500 °C to obtain vanadium oxide-deposited biochar. The metal deposition of 3 wt% increased the CO₂ adsorption capacity of the biochar to 71.85 mg/g under the same adsorption conditions, which can be attributed to the significant contribution of vanadium oxide to CO₂ chemisorption. Here, vanadium oxide could create oxygen vacancy on the LW surface which further react with CO₂ in the atmosphere. Kinetic studies revealed that the Avrami model could accurately predict the CO₂ adsorption behaviour, indicating both physisorption and chemisorption contributed to the adsorption. The activation energy for CO₂ uptake was calculated at around − 8.04 kJ/mol. The sustainable performance of metallized biochar was demonstrated in several cycles of CO₂ adsorption–desorption. In addition, this adsorbent showed high affinity towards CO₂ over air, CH₄ and N₂. The results of this study present the prospective potential of this sustainable adsorbent for large-scale post-combustion CO₂ capture.