Synthesis and characterization of KOH@Graphene oxide-Fe3O4 as a magnetic composite adsorbent for CO2 capture

Abstract

In this study, Fe3O4 nanoparticles were incorporated on graphene oxide (GO) layers to maintain the surface area of GO, while GO-Fe3O4 maintained their nanostructure. In order to enhance the alkaline natural of GO-Fe3O4, a 0.1 N KOH solution was added using an impregnation method. Brunauer-Emmett-Teller analysis showed that the adsorbent with a pore diameter of 15.05 nm was in the mesoporous range. The KOH@GO-Fe3O4 was tested for CO2 adsorption at temperature in range of 298–338 K and pressure range of 1–9 bar. The highest CO2 adsorption capacity of 6.812 mmol/g was obtained using 0.5 g of adsorbent at 298 K and 9 bar. The isotherm results showed that the Sips model gives the best fit to the experimental data obtained at 298 K and 9 bar. The adsorption mechanism between the KOH@GO-Fe3O4 active sites and CO2 molecules was physisorption. The best kinetic model was the Elovich model, which demonstrated a good fit of these associations to the linear function at 308 K. The thermodynamic results show that the highest capacity of CO2 capture was 6.812 mmol/g, which was achieved at low temperature when compared to other GO-based adsorbents. The thermodynamic parameters confirmed that CO2 adsorption was exothermic and physical. Thermogravimetric analysis and regeneration studies showed that KOH@GO-Fe3O4 has high thermal stability and regenerability.