A review of biomass-based carbon dioxide adsorbents research

Excessive CO₂ emissions pose a severe environmental threat, driving interest in carbon capture technologies. Biomass-derived activated carbon (BAC) emerges as a promising adsorbent due to its renewable feedstocks, cost-effectiveness, and tunable properties. This review comprehensively analyzes recent advances in BAC for CO₂ capture. Key findings indicate that agricultural/forestry wastes are optimal feedstocks, while alkali/alkaline earth metals and N/S-containing functional groups enhance surface alkalinity and CO₂ affinity. Pyrolysis is identified as the preferred preparation method for optimizing pore structure. Physical activation (CO₂, steam) and chemical modification (KOH/NaOH, amine grafting, metal oxide impregnation) significantly improve porosity and adsorption capacity. Notably, N-doping increases CO₂ uptake by 31.6–55.2 %, and microporous volume (0.59–0.71 cm³/g) is critical for performance. However, challenges include high energy consumption during KOH activation, feedstock variability impacting consistency (>22 % ash content differences), competitive adsorption from flue gas impurities (>30 % capacity loss), and metal leaching risks. Future research should prioritize in-situ mechanistic studies, heteroatom co-doping, and scalable production techniques to advance industrial deployment.