Synthesis and Characterization of Novel Modified SBA-15/PSF Nanocomposite Membrane Coated by PDMS for Gas Separation

SBA-15 nanoparticles were prepared by in situ assembly of inorganic precursors and CTAB. The structure of nanoparticles was characterized by X-ray diffraction, transmission electron microscopy, particle size analysis, and $N2$ adsorption techniques. The surface modification of particles in order to perfect dispersion in PSF matrix was performed by DMDCS and APTMS as new modification agents. Thermogravimetric analysis and scanning electron microscopy analysis were applied to investigate thermal stability and quality of distribution of particle in the nanocomposite membrane, respectively. The PDMS was used to coat the possible defects of synthesized membranes. For all gases (⁠$N2$⁠, $CO2$⁠, $CH4$⁠, and O2), the permeance of uncoated DMDCS modified SBA-15/PSF (20 wt %) raised from 16 to 31.6, 0.47–0.99, 0.45–1.1 and 2.75–5.33 for $CO2$⁠, $N2$⁠, $CH4$⁠, and $O2$⁠, respectively in comparison with PSF. The corresponding values of $CO2$⁠, $N2$⁠, $CH4$⁠, and $O2$ permeances through uncoated APTMS modified SBA-15/PSF (20 wt %) enhanced to 29.12, 0.8, 0.85, and 4.75 respectively, compared with neat PSF membrane. The ideal selectivities of $CO2/CH4$ and $O2/N2$ for DMDCS modified SBA-15 (20 wt %) nanocomposite membranes coated by 30 wt % PDMS solution enhanced from 26 to 35 and from 5.4 to 7.1, respectively. Using APTMS as modification agent resulted in higher selectivity of $CO2/CH4$ (38.2) and $O2/N2$ (7.2) than those of DMDCS modified. The measured actual selectivities of $CO2/CH4$ and $O2/N2$ and permeances of all gases tested are a few amounts lower than ideal selectivities and permeances of gases in single gas permeation tests but are still much higher than those for pure PSF.