Synthesis of nitrogen doped activated carbon/polyaniline material for CO2 adsorption

The equilibrium adsorption isotherms of carbon dioxide and nitrogen on the nitrogen doped activated carbon (NAC) prepared by the chemical activation of a pine cone-based char/polyaniline composite were measured using a volumetric technique. CO2 and N-2 adsorption experiments were done at three different temperatures (298, 308, and 318K) and pressures up to 16bar, and correlated with the Langmuir, Freundlich, and Sips models. The Sips isotherm model presented the best fit to the experimental data. The N-doped adsorbent showed CO2 and N-2 adsorption capacity of 3.96mmolg(-1) and 0.86mmolg(-1), respectively, at 298K and 1bar. The selectivity predicted by ideal adsorbed solution theory (IAST) model was achieved 47.17 for NAC at 1bar and y(N2)=0.85 which is a composition similar to flue gas. The results showed that NAC adsorbent has a high CO2-over-N-2 selectivity in a binary mixture. The relatively fast sorption rate of CO2 on NAC compared to N-2 indicates the stronger affinity between CO2 and amine groups. The isosteric heat of adsorption of CO2 by the NAC demonstrated the physico-chemical adsorption of CO2 on the adsorbent surface. These data showed that prepared NAC could be successfully applied in separation of CO2 from N-2.