Performance of CO2 Adsorption on Modified Activated Carbons Derived from Okara Powder Waste: Impacts of Ammonia Impregnation

The activated carbons (ACs) derived from okara powder waste with high surface areas were modified with ammonia aqueous solution impregnation in an autoclave to enhance their CO2 adsorption properties. The impregnated ACs were characterized, where the chemical composition and properties of the ACs were analyzed by SEM-EDX and FTIR. Activated carbons were functionalized with ammonia aqueous solution (25%) through a hydrothermal process within 24, 48, and 72 h. The adsorption performance of CO2 onto carbon samples was experimentally evaluated through a TPD CO2 measurement. FTIR spectra confirm the N-containing in N-modified activated carbons and the presence of the –C=O stretch and N-H groups. CO2 uptakes of activated carbons are 0.24; 1.78; 2.24; and 1.26 mmol/g, which are relatively comparable with those of activated carbons studied in the literature.