Fabrication and characterization of dual layer PEBAX‐SiO2/polyethersulfone nanocomposite membranes for separation of CO2/CH4 gases

Abstract

AbstractA new method of fabricating thin film composite (TFC) membranes is presented through a one‐step co‐casting technique. In this method a dense layer of poly(ether‐block‐amide) (PEBAX‐1657) was formed on a porous support of polyethersulfone (PES) in one step by immersing the cast films in a coagulation bath of n‐hexane. To assess the impact of silica (SiO2) nanoparticles on characteristics of the fabricated membranes, dual‐layer nanocomposite membranes containing 2.5, 5, and 7.5 wt% of SiO2 nanoparticles in the dense layer were also prepared. Physical and mechanical properties of membranes were evaluated using scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy, X‐ray diffraction, water contact angle and tensile strength measurements. SEM images revealed that a defect‐free top‐layer was formed on a porous substrate and both layers were adhered together properly. These images also showed that sub‐layer's microstructure was affected by addition of SiO2 nanoparticles to the PEBAX matrix. Gas permeation properties of membranes were recorded for pure CO2 and CH4 at room temperature and pressures in the range of 4–6 bars. Addition of SiO2 nanoparticles up to 5 wt% enhanced CO2/CH4 selectivity of the membranes, while at higher SiO2 nanoparticles loading (7.5 wt%), the selectivity was reduced.