Facile and efficient nitrogen modified porous carbon derived from sugarcane bagasse for CO₂ capture: Experimental and DFT investigation of nitrogen atoms on carbon frameworks

The use of sustainable feedstock and low-cost precursor is an important prerequisite in developing sorbents for CO₂ capture. In this research, nitrogen-modified porous carbon materials with varying ratio of carbon-melamine (1:1, 1:2 and 1:3) were synthesized from a sustainable and green-initiated feedstock, sugarcane bagasse, and solid-state impregnation of melamine and investigated as alternative sorbent in CO₂ capture. This gives an insight into the effect of increasing the nitrogen content of porous carbon material on CO₂ capture. The CO₂ uptake of the nitrogen-modified carbon was at least 35% more than that of the pristine porous carbon. Modified carbon with carbon-melamine ratio (1:2) demonstrates the highest CO₂ uptake at ambient pressure and temperature (3.34 mmol/g), making it comparable to similar materials that have been reported. The superiority demonstrated by this adsorbent was attributed to a balance between its textural properties and chemical functionalization using nitrogen. The synthesized material also showed high selectivity and regeneration capacities. Adsorption of CO₂ and N₂ on pristine and nitrogen modified carbon material was also examined using density functional theory (DFT) calculation at B3LYP/6-31G (d) level. The result obtained revealed that nitrogen-doped carbon material exhibited higher tendency to CO₂ adsorption than pristine carbon material in accordance with the hard-soft acid-base (HSAB) principle. This work provides a new and efficient route for the synthesis of nitrogen modified carbon and application for similar adsorption processes.