Enhanced CO₂ adsorption by activated carbon impregnated with PEI

To reduce carbon dioxide emissions into the atmosphere, adsorption is believed to be one of the most attractive methods for post-combustion treatment of flue gas. In this work, activated carbon (AC) was modified with polyethylenimine (PEI) via impregnation in order to enhance CO2 adsorption capacity. Adsorption was carried out in a temperature range from 30 to 75 °C of five different gas pressures up to 1 atm. TG-DTA, FT-IR, UV-visible spectrometer, and BET were used to characterize the adsorbents. At 30 °C, 0.22 wt.% PEI/AC gave lower adsorption capacity than the AC. That may be due to the pore filling effect that blocks the pores of the adsorbent preventing CO2 to diffuse into the pores. Surprisingly, at 75 °C, 0.28 wt.% PEI/AC gave higher adsorption capacity when compared with the AC and other PEI loadings. The modified AC maintained its adsorption capacity with minimal loss after regeneration.