Assembly of amine-functionalized graphene oxide for efficient and selective adsorption of CO2

Abstract

Amine-functionalized solid adsorbents show promising potential for the capture of CO2, a harmful greenhouse gas which is regarded as the major cause of global warming. In this study, three amine functionalities of triethylenetetramine (TETA), pentaethylenehexamine (PEHA), and meta-phenylenediamine (MPD) were separately anchored to the GO surface. The analyzing methods, including Fourier transform infrared spectroscopy (FTIR), CHNS elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2 adsorption-desorption were used to study the characteristics of the synthesized GO series. The equilibrium adsorption of CO2 on GO and amine-functionalized GO (GO-NH2) were experimentally measured at 298, 308, and 318 K and pressure range of 0–14 bar. The CO2 uptake was strikingly improved from 0.39 mmol/g for GO to 0.61, 0.74, and 0.91 mmol/g for GO-PEHA, GO-TETA, and GO-MPD adsorbents at 298 K and 1 bar, respectively. The prediction of the selectivity of the adsorbents based on the ideal adsorbed solution theory (IAST) exhibited the excellent selectivity of the adsorbents, in particular for GO/MPD around 21.21 for the selective capture of CO2 over N2 under ambient conditions. The isosteric heats of adsorption indicated the physisorption of CO2 on amine-modified GO samples and also its precursor. The high CO2/N2 selectivity obtained in this study and cyclic operation tests prove that GO-NH2 samples can be applied as an impressive adsorbent to capture CO2 from flue gas.