Removal Of Carbon Dioxide From Flue Gases By Adsorption On Activated Carbon

Abstract

Carbon dioxide is one of the most prevalent greenhouse gases in the atmosphere, and it will continue to dominate in future. Flue gas emitting from power plants is potential source of carbon dioxide. The recovery of carbon dioxide from flue gases, hence, is an important step in solving global environmental problems. The present study is focused on equilibrium, kinetic and dynamic performance of carbon dioxide adsorption on activated carbon. Two commercially available activated carbon WS 480 and AP 360 were used in this study. These activated carbon were also treated with nitric acid and different amines (n-butylamine, di-butylamine and aniline). Samples were characterized by Thermo Gravimetric Analysis, Surface area, Pore size distribution and FT-IR spectroscopy. The gravimetric equilibrium adsorption isotherms were measured at 303 K and 333 K for both carbon dioxide and nitrogen. The equilibrium adsorption isotherm data were fitted into various adsorption isotherms models such as Langmuir model, modified Langmuir model and Dubinin-Astakhov model. The heat of adsorption and selectivity were calculated from experimental data as well as from Langmuir model data. Intracrystalline diffusion coefficients were also measured from gravimetric uptake data and it was observed that carbon dioxide is diffusing faster than nitrogen. The dynamic adsorption was studied for feed gas consisting 15.0 ± 0.5 % and 85.0 ± 0.5 %, carbon dioxide and nitrogen respectively. From the experimental breakthrough curve, it was found that the dynamic adsorption is equilibrium controlled rather than mass transfer controlled. The breakthrough curve was modeled and compared with experimental breakthrough data and it found to match with experimental data. Model assumes instantaneous equilibrium between the solid phase and gas phase based on Langmuir adsorption model. It was found that nitric acid treated activated carbon has higher equilibrium and dynamic adsorption capacity.