Non Solvent Effect on Polysulfone Membrane for Carbon Dioxide Removal from Natural Gas

Gas separation by selective transport through membranes is one of the fastest growing branches in membrane technology. Polymeric membrane is a type of membrane that is most favorable to be used as the gas separation membrane. In this study Polysulfone has been chose as the material for the membrane fabrication. This is due to the good separation properties, low cost and not easily plasticized by highly sorbing plasticization gases. In order to fabricate the membrane, wet phase inversion process has been used. In this process, polymer material that is polysulfone was dissolved together with the solvent which is Dichloromethane (DCM) and 1-Methyl-2 Pyrrolidone (NMP). Then the polymer solution was casted to get a layer of membrane shape before immersing it in a non-solvent coagulation bath to allow wet phase inversion process to occur. In this study, the non-solvent that is used as a coagulation medium, was varied between ethanol and water. The usage of this different non solvent varied the phase change rate between the non solvent and solvent thus will vary the morphology of the membrane formed. By using water as the non solvent, the internal coagulation rate between the solvent and the non solvent was increased thus produced membrane with large macrovoid in the substructure. Meanwhile by using Ethanol as the non solvent, it will reduce the macrovoid and will increase the selectivity of the membrane. The characteristic of the polysulfone membrane was characterized by using Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR) test, and Universal Testing Machine (UTM). The gas separation behavior of the membrane was determined by using membrane permeation system with different sets of feed pressure of CO2and CH4 gases. The separation performance of the membrane was determined by calculating the selectivity and the permeability of the membrane. PSF membrane that used 100% Ethanol as the non solvent showed the promising performance in term of selectivity and permeability. The results showed that the polymer and the non solvent pair controlled the morphology of the membrane and eventually affect the performance of the PSF membrane.