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 77K, 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.