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.
Keywords: Activation conditions; CO(2) adsorption; Carbons; Cellulose; Gas selectivity; Ultra-micropores.
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