A Theoretical Mechanism Study on the Ethylenediamine Grafting on Graphene Oxides for $$\hbox {CO}_{2}$$ CO 2 Capture

Graphene oxide aerogel assembled by dimethylaminopropylamine /N-isopropylethylenediamine for the removal of copper ions

Graphene Oxide Monolith composites (GOMs) were prepared using dimethylaminopropylamine (DMPDA) and N-isopropylethylenediamine (IPEDA) with one-step method in water medium, respectively. Fourier transform-infrared (FTIR), X-Ray Diffraction (XRD) tests proved the formation of new structure and credible interactions between crosslinkers and GO. Scanning electron microscopy (SEM) showed distinct change of morphology after complexing. Bath adsorption tests suggested that the fast adsorption of copper ions (II) was strongly affected by pH, ionic strength, temperature, and concentration, etc.. Isothermal Langmuir and Freundlich kinetic model showed the different degree of fitting conformity according to different conditions. SEM and XRD further provided a supporter of adsorption of copper ions onto GOMs, and Density functional theory (DFT) was used to analyze the crosslinking details of DMPDA and GO and the adsorption mechanism of copper ions. The theoretical calculation results clarified an efficacious and quantitative understanding for the crosslinking and adsorption mechanism.

Effect of Varying Amine Functionalities on CO2 Capture of Carboxylated Graphene Oxide-Based Cryogels

Graphene cryogels synthesis is reported by amine modification of carboxylated graphene oxide via aqueous carbodiimide chemistry. The effect of the amine type on the formation of the cryogels and their properties is presented. In this respect, ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), were selected. The obtained cryogels were characterized by Fourier Transformed Infrared spectroscopy, thermogravimetric analysis, X-ray spectroscopy, and Scanning electron microscopy. The CO2 adsorption performance was evaluated as a function of amine modification. The results showed the best CO2 adsorption performance was exhibited by ethylenediamine modified aerogel, reaching 2 mmol g-1 at 1 bar and 298 K. While the total N content of the cryogels increased with increasing amine groups, the nitrogen configuration and contributions were determined to have more important influence on the adsorption properties. It is also revealed that the residual oxygen functionalities in the obtained cryogels represent another paramount factor to take into account for improving the CO2 capture properties of amine-modified graphene oxide (GO)-based cryogels.