Membrane technology has gained great importance in carbon dioxide separation processes. Membrane processes are simple, energy-efficient, which can be economical in comparison to traditional separation technologies. In this research Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) membranes with controlled asymmetric microstructure and functionalized with room temperature ionic liquid (RTIL) are used for the separation of C0₂ from a gas stream. Polymeric membranes are fabricated from PVDF-HFP and polyethylene glycol (PEG) using the phase inversion method. To produce the optimum polymeric membrane, several parameters that influence the membrane structure and morphology such as concentration of polymer (16-20 wfl/o of PVDF-HFP), type of solvent, organic additives (0- 10 wt% PEG), evaporation time (0- 180 second) and coagulation bath medium (0-75 wt% ethanol concentration) during phase inversion were studied. The membranes were characterized by Scanning Electron
Microscopy (SEM) Fourier Transform Infrared (FTIR) Spectroscopy, Surface Area Analysis (BET), Viscosity and Porosity Analysis, and X-ray diffractometer (XRD). In the current research an experimental set-up was designed and build, which was capable of measuring gas permeability through various types of polymer membranes, under a wide range of operating conditions. Pure single gas C0₂ and N₂ were used to study the efficiency of the membrane in permeance and permselectivity in membrane permeation test. The polymer membranes have been modified with a selective layer made from polyethylene glycol (PEG), Ionic liquid 1-butyl-3-methylimidazolium bis (trifluoromethyl) sulfonyl imide, [bmim +][NTf2 -] and Hydrotalcite (HT). A membrane configuration of PVDF-HFP/PEG 17/ 3 wt% membrane (F3) and 35 wt% ethanol concentrations was found to give good permeance and permselectivity being 2970 GPU and 2.72 respectively. This membrane was improved by adding 25.55 wt% RTIL to prepare the supported ionic liquid membrane (SILM) using vacuum immobilization technique (F3-IL) and the result showed a little decrease in permeance (2500 GPU) but a clear increase in permselectivity (19.26). Also, adding a thin selective layer to the membrane (F3-IL-1.0 HT) resulted in a significant increase in permeance (3640 GPU) without any loss in permselectivity (19.11 ).
