Fabrication of pebax-1657-based mixed-matrix membranes incorporating N-doped few-layer graphene for carbon dioxide capture enhancement

In this study, an environmentally friendly method was developed to fabricate N-doped few-layer graphene (N-FLG)/Pebax mixed-matrix membranes (MMMs) for CO2 capture. A supermixer was introduced to ensure homogeneity of the N-FLG in the Pebax solution, and a highly efficient method of N-FLG/Pebax MMM preparation was achieved. The membrane structures were analyzed by SEM, while the N-FLG morphology was examined by SEM, AFM, XPS and EDX. A detailed molecular simulation was applied to mimic and predict the behavior of and interaction between membranes and gas molecules. Through the simulation, an independent analysis of transport-related characteristics, such as diffusivity, solubility and permeability, was achieved. In addition, the simulation indicated that the affinity of N-FLG for CO2 molecules improves the CO2 capture performance, that the membranes are solubility-dependent when prepared with low contents of N-FLG and that the effect of diffusivity increases as the addition of N-GO increases above 5 wt%. The simulation results were highly correlated with the experimental results, while the experimental gas permeability results showed that the optimal performance of N-FLG/Pebax MMM was obtained with the addition of 4 wt% N-FLG, providing CO2 permeability and CO2/N-2 selectivity of 239.8 Barrer and 95.5, respectively. Pebax-1657-based MMMs incorporating N-FLG nanosheets fabricated by an environmentally friendly method can therefore be considered a promising material for CO2 capture applications.