Graphene nanosheets from hazardous/solid wastes: An efficient CO2 capture material

Highly efficient CO2 capture at elevated temperatures has been achieved with a few-layered graphene nanosheets (GNS) prepared from solid waste generated from high energy explosive materials manufacturing industry. These materials were used to adsorb CO2 from simulated industrial flue gases with an aim to reduce CO2 concentration in the atmosphere. The GNS is a microporous material with pore volume of 0.59 cm3 g−1 and 70% of pores were of average size of 0.55 nm. The surface area of GNS was 964 m2 g−1 which was reduced to 268 m2 g−1 when the number of layers in GNS increased to >50. The adsorption capacity of 3.89 mmol g−1 was achieved at 303 K/0.5 bar and this adsorption capacity was further increased to 23.63 mmol g−1 at 303 K/20 bar. The Sips adsorption model was used for evaluating the relationship between surface heterogeneity of GNS and adsorption capacity at temperature. The GNS materials selectively captured CO2 in the presence of gases mixtures (CO2/N2 and CO2/CH4). The fast adsorption kinetics and recycling stability of GNS for about 20 cycles suggests that the solid adsorbents prepared in this study are efficient and technically feasible to capture CO2 from industrial stacks and other real-life situations.