The development of activated carbon from corncob for CO₂ capture

The accumulation and incineration of crop waste pollutes the environment and releases a large amount of CO₂. In this study, corncob crop waste was directly activated using solid KOH in an inert atmosphere to prepare porous activated carbon (AC) to capture CO₂, and to introduce N-containing functional groups that favour CO₂ adsorption, urea was mixed with corncob and KOH to prepare N-doped AC. The physical and chemical properties of the AC were characterized, and the effects of the mass ratio of KOH and urea to corncob, the activation temperature and time as well as regeneration were investigated to explore the optimal preparation process. The pores in the AC are mainly micropores, with the specific surface area and pore volume reaching 926.07 m² g^-1 and 0.40 cm³ g^-1 for KOH-activated corncob and 1096.70 m² g^-1 and 0.48 cm³ g^-1 after N-doping; the C-O plus O-H ratio and the -NH- ratio, which favour CO₂ adsorption in N-doped AC were 6.04 and 1.92%, respectively. The maximum adsorption capacities for KOH-activated corncob before and after N-doping were 3.49 and 4.58 mmol g^-1, respectively, at 20 °C and remained at 3.44 and 4.52 mmol g^-1 after ten regenerations. The prepared corncob-based AC showed good application prospects for CO₂ capture.