A grand canonical Monte Carlo study of SO₂ capture using functionalized bilayer graphene nanoribbons

Grand canonical Monte Carlo (GCMC) simulation is used to study the adsorption of pure SO₂ using a functionalized bilayer graphene nanoribbon (GNR) at 303 K. The functional groups considered in this work are OH, COOH, NH₂, NO₂, and CH₃. The mole percent of functionalization considered in this work is in the range of 3.125%-6.25%. GCMC simulation is further used to study the selective adsorption of SO₂ from binary and ternary mixtures of SO₂, CO₂, and N₂, of variable composition using the functionalized bilayer graphene nanoribbon at 303 K. This study shows that the adsorption and selectivity of SO₂ increase after the functionalization of the nanoribbon compared to the hydrogen terminated nanoribbon. The order of adsorption capacity and selectivity of the functionalized nanoribbon is found to follow the order COOH > NO₂ > NH₂ > CH₃ > OH > H. The selectivity of SO₂ is found to be maximum at a pressure less than 0.2 bar. Furthermore, SO₂ selectivity and adsorption capacity decrease with increase in the molar ratio of SO₂/N₂ mixture from 1:1 to 1:9. In the case of ternary mixture of SO₂, CO₂, N₂, having compositions of 0.05, 0.15, 0.8, the selectivity of SO₂ over N₂ is higher than that of CO₂ over N₂. The maximum selectivity of SO₂ over CO₂ is observed for the COOH functionalized GNR followed by NO₂ and other functionalized GNRs.