Study of carbon dioxide adsorption using adsorbent modified with piperazine

Abstract

Adsorption of CO₂ was performed with an adsorbent impregnated with piperazine. The objective was to optimize the CO₂ adsorption capacity, via piperazine loading, moisture, and adsorption temperature. The surface morphology of the unmodified and impregnated activated carbon was characterized using a scanning electron microscope. There were only slight differences in the surface and pore size. A surface area analyzer showed a decrease in surface area and pore volume of the micropore due to the pore blocking effect, but there was negligible change in the mesopore. The average maximum piperazine loading of 3,12 wt % was impregnated on the activated carbon and was detected by a gas chromatography-flame ionization detector. The adsorption capacity of 4 % CO₂ on the unmodified activated carbon (Act.C), moisturized adsorbent, and 3.12 wt % piperazine loaded on activated carbon (Pz-Act.C) at room temperature and atmospheric pressure reached 16.47 mg/g, 6.12 mg/g, and 23.17 mg/g, respectively. It was found that moisture could deactivate the active sites of the adsorbent. The effects of temperature were also studied at 25 °C, 45 °C and 55 °C; the adsorption capacity decreased as the temperature increased due to the limitation of maximum piperazine loading of 3.12 wt%. The adsorption capacity of the adsorbents under the effect of temperature at 45 °C and 55 °C was 9.25 mg/g and 7.64 mg/g for Act.C, 3.64 mg/g and 2.95 mg/g for moisturized adsorbent. 12.63 mg/g and 8.76 mg/g for 3.12 wt % Pz-Act.C.