Influence of Amine Grafting on Carbon Dioxide Adsorption Behaviors of Activated Carbons

In this work, the amine grafting treated activated carbons were studied for carbon dioxide adsorbent. The surfaces of activated carbon were functionalized by 3-chloropropyltrimethoxysilane, which was subsequently grafted with amine compounds tris-(2-aminoethyl)amine and tri-ethylenetetramine and subjected to comparison. The surface functional groups of the amine grafted activated carbons were characterized using XPS. The textural properties of the amine grafted activated carbons were analyzed by $N_2$/77 K isotherms. Carbon dioxide adsorption behaviors of the amine grafted activated carbons were examined via the amounts of carbon dioxide adsorption at 298 K and 1.0 atm. From the results, tris-(2-aminoethyl)amine grafted activated carbons showed 43.8 $cm^3$/g of carbon dioxide adsorption while non-treated activated carbons and triethylenetetramine grafted activated carbons showed less carbon dioxide adsorption. These results were thought to be due to the presence of isolated amine groups in the amine compounds. Tris-(2-aminoethyl)amine grafted activated carbons have basic features that result in the enhancement of adsorption capacity of the carbon dioxide molecules, which have an acidic feature.