Carbon dioxide capture with polyethylenimine-functionalized industrial-grade multiwalled carbon nanotubes

Industrial grade multiwalled carbon nanotubes (IG-MWCNTs) were functionalized with polyethylenimines (PEIs) for CO₂ capture from simulated flue gas. Ethylenediamine end-capped PEI (PEI-EC) impregnated IG-MWCNTs was found to exhibit a significantly higher adsorption capacity than other branched PEIs impregnated IG-MWCNTs. The PEI-EC impregnated IG-MWCNTs were characterized with various experimental methods including N₂ adsorption/desorption isotherms, X-ray diffraction, and thermogravimetric analysis. The CO₂ adsorption behavior of the PEI-EC impregnated IG-MWCNTs is influenced by PEI loading and adsorption temperature. The PEI-EC impregnated IG-MWCNTs exhibit a CO₂ adsorption capacity as high as 2.538 mmol/g at 343 K, and can be completely regenerated higher than 403 K. The CO₂ adsorption/desorption kinetics of the PEI-EC impregnated IG-MWCNTs was investigated with Avrami's fractional order kinetic model. The activation energy of the CO₂ adsorption/desorption was calculated from Arrhenius equation and used to evaluate the performance of the adsorbent.