Influence of amine surface treatment on carbon dioxide adsorption behaviors of activated carbon nanotubes

In this work, the amine-treated activated carbon nanotubes (A-MWNTs) were used to investigate the CO ₂ adsorption behaviors. A-MWNTs were prepared by impregnation with amine in methanol after chemical activation methods using a KOH. The characteristics of amine-treated A-MWNTs were studied by X-ray photoelectron spectroscopy (XPS), N ₂ adsorption, desorption isotherms at 77 K. The specific surface area and pore volume of the A-MWNTs were analyzed by BET equation, BJH method, and t-plot method. CO ₂ capture capacity as a function of temperature was measured by temperature programmed desorption (TPD). From the results, the amine treatment increased the basicity and nitrogen content of the A-MWNTs. The CO ₂ adsorption capacity of the amine-nontreated A-MWNTs showed the highest value at room temperature and then greatly decreased with increasing the temperature. However, the amine-treated A-MWNTs presented a softer slope with temperature compared to the amine-nontreated ones. It was due to the strong interactions between CO ₂ and amino groups presented on the carbon surfaces studied.