Functionalization of palm shell based activated carbon with amine groups for carbon dioxide capture

Surface of activated carbon can be functionalized with amine groups to enhance their capacity for CO₂ adsorption. Amine functionalized solid sorbents were prepared by anchoring two types of amine compounds, namely ethylenediamine (EDA) and 2-chloroethylamine hydrochloric acid (CEA) on the surface of palm shell based activated carbon (PSAC). Samples of PSAC were first oxidized by nitric acid using three different available setups to ensure about creation of a significant amount of oxygen containing groups on the surface. At the second stage, the best oxidized sample was modified by anchoring EDA and CEA on the surface to produce a superior CO₂ adsorbent. Several quantitative and qualitative methods were used to characterize the prepared samples: Nitrogen adsorption at 77 K, proximate and ultimate analysis and temperature programmed desorption (TPD). Moreover, CO₂ adsorption study was carried out using CO₂ adsorption isothermal profile at 30°C and temperature- programmed (TP) CO₂ adsorption test. All modified samples had a lower surface area than the virgin PSAC. The best modified sample presented an increase of 45% in CO₂ capture capacity at 100°C. On the other hand, on the basis of unit surface area, CO₂ capture capacity of amine modified samples was much higher, compared to the parent sample. Furthermore, the modified samples showed a less dependency of their CO₂ capacity on temperature indicating chemisorption of the adsorbate on the PSAC surface.