Thermodynamics and regeneration studies of CO2 adsorption on activated carbon.

The kinetic and thermodynamic studies of CO₂ adsorption on activated carbon were carried out in a fixed bed. Six different CO₂ concentrations (from 5% up to 18 vol.%) and four temperatures (303 K, 313 K, 323 K, and 333 K) were applied to investigate dynamic adsorption behaviors. It showed that the increase in temperature led to faster adsorption kinetics, but also reduced the adsorption capacity. An isotherms modeling was made by the Langmuir isotherm model. The experimental isotherms data were well fitted. Then, based on the adsorption isotherms, the isosteric heats of CO₂ adsorption were determined by Clausius-Clapeyron equation. The calculated isosteric heat declined slightly with the adsorbed amount on activated carbon, and had an average value of 16.09 kJ/mol, which is much lower than the actual heat of adsorption measured by calorimeter. Moreover, regeneration experiments by vacuum evacuation (<10 kPa) were conducted to assess the regeneration efficiency (RE) of activated carbon. Regeneration efficiency increased with the reduction of vacuum pressure and reached over 90% at the vacuum of 4 kPa. A temperature swing integrated into the vacuum evacuation process resulted in a remarkable increase of RE with an increase in regeneration temperature, which confirmed the favorable effect of temperature on regeneration of activated carbon and providing almost full regeneration. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]