Melamine-nitrogenated mesoporous activated carbon derived from rice husk for carbon dioxide adsorption in fixed-bed

This work presents the preparation of melamine-nitrogenated mesoporous activated carbon from rice husk via single step chemical activation with phosphoric acid and subsequent modification with melamine for efficient carbon dioxide adsorption. The nitrogen-containing carbons were characterized for their textural and chemical properties and thereafter tested for carbon dioxide adsorption in fixed-bed adsorption system. Characterization of the prepared adsorbent reveals better textural properties with high basicity, porosity and nitrogen functionalities indicating that nitrogen was successfully incorporated on to the surface of activated carbons. The nitrogen-containing activated carbon exhibited a maximum carbon dioxide capacity of 5.43 mmol/g at 30 °C attributing to well-developed porous structure and high surface basicity. The nitrogen functionalities in addition to textural properties, surface chemistry and nitrogen content played vital roles towards enhanced adsorption capacity of the prepared adsorbent. The isotherm and kinetic studies showed that Freundlich isotherm and Avrami model best fit the experimental data thus, indicating the heterogeneity of the adsorbent surface. The CO2 molecules were completely released during the regeneration process and thus showed good regeneration performance with stable carbon dioxide adsorption capacity after twelve cycles.