Figure 4. Comparison between rGO membrane and ZIF-8 membrane for CO₂/CH₄ separation.

Molecular simulations were carried out to estimate the number of gas molecules passing through the rGO membrane as a function of simulation time averaged over five independent simulations (CO₂ and CH₄ are represented as blue and magenta squares, respectively). The CO₂ result obtained from MD simulations was further fitted using the membrane process model (see Methods section), and the CO₂ permeance of the rGO membrane was determined to be 2.1 × 10⁻⁴ (mol m⁻² s⁻¹ Pa⁻¹; solid blue line). As a comparison, the corresponding CO₂ (solid dark yellow line) and CH₄ (dashed dark yellow line) results using ZIF-8 membranes are also provided, which were estimated using the membrane process model (see Methods section) with experimentally reported parameters23.