Carbon dioxide adsorption studies on modified montmorillonite clay/reduced graphene oxide hybrids at low pressure

Abstract

The effect of modification of Montmorillonite clay (MMT) and the development of its hybrid with reduced graphene oxide was studied for CO2 adsorption at low pressure. Novel polyphosphoric acid modified montmorillonite (PMMT) clay was synthesized by cation exchange reaction to improve the surface area and thereby improving the carbon dioxide adsorption capacity. The MMT clay, polyphosphoric acid modified clay (PMMT), and amino modified clay (AMMT) were hybridized with reduced graphene oxide (rGO) by in-situ hydrothermal reduction of graphite oxide for CO2 adsorption studies. The hybrids were characterized using X-ray diffraction (XRD) analysis, Fourier Transform Infrared (FTIR) analysis, Field Emission Scanning Electron Microscopic (FESEM) and Transmission Electron Microscopic (TEM) analyses. The Brunauer–Emmett–Teller (BET) surface area analysis confirmed a surface area of 50.7709 m²/g for PMMT/rGO hybrid, which was higher than that of MMT/rGO and AMMT/rGO hybrids. In general, all hybrids were active in CO2 adsorption at comparatively low pressure [ranging from 0 to 900 mmHg]. PMMT/rGO hybrid showed highest CO2 adsorption of 0.49 mmol/g and this was 42% more in CO2 adsorption when compared to other materials studied in this paper. The low pressure CO2 adsorption values obtained for PMMT/rGO hybrid was substantially good when compared to the literature results and this shows the importance of clay based materials for the development of efficient adsorbent for CO2.