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 N-2 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 Avramis 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.