Fabrication of a Polyetherimide/ZIF-8 Composite Membrane for Separating Carbon Dioxide from Methane

In the present work, a polyetherimide/ZIF-8 composite membrane was fabricated by solution casting technique. The prepared membranes were Characterized using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR), energy dispersive X-ray (EDAX) and X-ray diffraction (XRD). Furthermore, the membrane's performance in separating carbon dioxide and methane was analyzed through single gas permeability measurements. FTIR-ATR spectrum of the prepared membrane confirmed the functional groups of polyetherimide. XRD analysis showed that the additive was well dispersed in the polymer, resulted in a reduction in the membrane's crystallinity. EDAX analysis confirmed the existence and proper dispersion of Zn particles in the membrane. Finally. The results of permeability tests showed that adding ZIF-8 to the membrane significantly increased its permeability and selectivity. The permeability of the composite membrane for CO2 gas was 5.91 GPU, more than twice that of the pure polyetherimide membrane. Additionally, the permeability for CH4 gas was 0.31 GPU, representing a significant improvement over the pure membrane's permeability of 0.17 GPU. The carbon dioxide/methane selectivity also rose from 15.3 in the pure membrane to 19.1 in the composite membrane. In conclusion, the study demonstrated that adding ZIF-8 to a polyetherimide matrix can improve the effectiveness of the resulting composite membrane for separating CO2 from CH4. The improvement in selectivity was primarily due to the increased solubility coefficient of carbon dioxide compared to methane in the composite membrane.