Modification of PVC with 1-Vinylimidazole for CO2/CH4 Separation: Sorption, Permeation and DFT Studies

To improve the gas separation performance of poly (vinyl chloride) membrane, 1-vinyl imidazole was grafted onto the poly (vinyl chloride) by free radical graft copolymerization. The synthesized of the graft copolymer was characterized by the elemental analyzer technique (CHN). The prepared membrane morphology was surveyed by Scanning Electron Microscope (SEM). The properties of thermodynamics of CO2 adsorption were investigated at various temperatures and pressures by quartz crystal microbalance (QCM). The experimental data were correlated by the dual-mode model. The calculated thermodynamics parameters of CO2 adsorption display that CO2 adsorption has the nature of exothermic. Also, methane and carbon dioxide gas permeability was measured. The effects of variation of temperature and feed pressure on the membrane performance were surveyed. The increment in temperature cause to decrement the selectivity of membrane for carbon dioxide/methane gases; whiles, the selectivity of the membrane was incremented by incrementing feed pressure. The outcomes indicate that the permeation selectivity of the grafted copolymer is more than those of the poly (vinyl chloride) membrane for CO2/CH4 gasses. Moreover, Density functional theory (DFT) computes corroborated that the interaction energy of grafted copolymer with CO2 is stronger than this of CH4.