Synthesis and Preparation of Asymmetric PVDF-co-PTFE/DES Supported Membrane for CO₂/N₂ Separation

Incorporation liquid into membrane polymer pores structure would overcome challenges in developing a membrane with increasing gas permeability while maintaining the excellent selectivity. Asymmetric Polyvinylidene fluoride-co-polytetrafluoroethylene (PVDF-co-PTFE) and PVDF-co-PTFE/Deep Eutectic Solvent (PVDF-co-PTFE/DES) supported membrane was prepared using phase inversion method. Membranes prepared were coated with 3 wt. % of polydimethylsiloxane (PDMS) in n-hexane and were dried in a room temperature. While, deep eutectic solvent (DES) was prepared by mixing choline chloride and ethylene glycol with a ratio of 1:3. The membranes was characterized using scanning electron microscopy (SEM), fourier transform infrared (FTIR) and gravimetric methodology to determine the membrane porosity. The membrane performance was carried out using gas permeation test at 3.5 psi. FTIR spectra revealed that existence of DES in the membrane pore structures. Empty PVDF-co-PTFE membrane coated with PDMS shows CO₂ permeance at 12 × 10³ GPU with CO₂/N₂ selectivity at 0.72. Interestingly, incorporation of DES showing an improvement for both CO₂ permeance and CO₂/N₂ selectivity up to 49% and 36% respectively. Thus, employing DES as a liquid filler into PVDF-co-PTFE matrix shows a promising membrane for CO₂/N₂ separation. (paper)