Acetic acid-mediated cellulose-based carbons: Influence of activation conditions on textural features and carbon...

In this work, we developed a simple methodology for producing highly porous carbons. Herein, we combined the hydrothermal method with chemical activation to fabricate cellulose-based, melamine modified porous carbons, using acetic acid as an additive. The preparation conditions including activation temperature, activation time, and melamine ratio were varied to obtain an optimized adsorbent exhibiting efficient textural features and maximized carbon dioxide (CO₂) adsorption uptake. By varying the preparation conditions, high specific surface area (SSA) (1260-3019 m² g^-1), microporosity in the range of 0.21-1.13 cm³ g^-1, and a well-developed porous structure was obtained. The optimized adsorbent exhibits an excellent CO₂ adsorption uptake of 297.05 mg g^-1 (6.75 mmol g^-1) and 174.4 mg g^-1 (3.96 mmol g^-1) at 273 K and 298 K at 1 bar, respectively, due to the existence of ultra-micropores (<0.68 nm, < 0.81 nm), high SSA (3019 m² g^-1), and high nitrogen content (8%). Furthermore, the role of micropores in the CO₂ adsorption process suggests that micropores between 0.68 nm and 1 nm exhibit high CO₂ adsorption potential. Additionally, all synthesized carbons exhibited a high isosteric heat of adsorption (45 kJ mol^-1) and a greater affinity for adsorbed CO₂ species than nitrogen (N₂) molecules. Thus, as-fabricated porous carbon adsorbents are an effective competitor for CO₂ uptake applications to mitigate global warming.