CO2 adsorption on carbonaceous materials obtained from forestry and urban waste materials: A comparative study.

Abstract

Abstract The increasing emissions of gaseous pollutants of anthropogenic origin, such as carbon dioxide (CO2), which causes global warming, have promoted a great interest in developing and improving processes that allow their mitigation. Among them, adsorption on porous materials has been proposed as a sustainable alternative. This work presents a study of CO2 equilibrium adsorption at low temperatures, (0, 10, and 20°C) over a wide range of low pressures, on activated carbon derived from eucalyptus (ES) and patula pine (PP) forest waste and carbonaceous material derived from waste tires (WT). Previously the precursors of these materials were prepared and characterized in terms of their physicochemical properties and thermochemically treated with phosphoric acid (ES and PP) and oxidized with nitric acid (in the case of WT). Additionally, these materials were used to obtain monoliths using uniaxial compaction techniques and different binding agents, obtaining better results with montmorillonite. All six adsorbent solids were characterized through their textural and chemical properties and proven in CO2 adsorption. The highest specific surface area (1405 m2/g), and micropore properties were found for activated carbon derived from eucalyptus allowing the highest adsorption capacity ranging from 2.27 mmol/g (at 0°C and 100 kPa) to 1.60 mmol/g (at 20°C and 100 kPa). The activated carbon monoliths presented the lowest CO2 adsorption capacities, however, the materials studied showed a high potential to be focused on CO2 capture and storage applications at high pressures. The isosteric heats of adsorption were also estimated for all the materials and results ranged from 16 to 45 kJ/mol at very low coverage explained in terms of the energetic heterogeneity and weakly repulsive interactions between adsorbed CO2 molecules.