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 CO2 adsorption at various adsorption temperatures, CO2 partial pressure, and amine loadings, it was found that Avrarni's fractional-order kinetic model provided the best fitting for the adsorption behavior of CO2. In order to find the optimal regeneration method, three desorption methods were evaluated for the regeneration of solid sorbents. The activation energy Ea of CO2 adsorption/desorption was calculated from Arrhenius equation and used to evaluate the performance of the adsorbent. The Ea decreased with increasing CO2 concentration, indicating that CO2 adsorption of amine-functionalized IG-MANCNTs is possibly intraparticle controlled. Meanwhile, because of the energy input of a vacuum pump, Ea for the vacuum swing regeneration method was less than that for temperature swing regeneration.