Kinetics studies of CO₂ adsorption/desorption on amine-functionalized multiwalled carbon nanotubes

The adsorption/desorption kinetics of carbon dioxide on tetraethylenepentamine (TEPA) impregnated industrial grade multiwalled carbon nanotubes (IG-MWCNTs) was investigated to obtain insight into the underlying mechanisms on the fixed bed. After evaluating four kinetic models for CO ₂ adsorption at various adsorption temperatures, CO₂ partial pressure, and amine loadings, it was found that Avramis fractional-order kinetic model provided the best fitting for the adsorption behavior of CO ₂. In order to find the optimal regeneration method, three desorption methods were evaluated for the regeneration of solid sorbents. The activation energy E_a of CO₂ adsorption/desorption was calculated from Arrhenius equation and used to evaluate the performance of the adsorbent. The E_a decreased with increasing CO₂ concentration, indicating that CO₂ adsorption of amine-functionalized IG-MWCNTs is possibly intraparticle controlled. Meanwhile, because of the energy input of a vacuum pump, E_a for the vacuum swing regeneration method was less than that for temperature swing regeneration.