Fabrication or preparation and characterization of new modified MCM-41/PSf nanocomposite membrane coated by PDMS

MCM-41 nanoparticles were prepared by in situ assembly of inorganic precursors and CTAB. The structure of nanoparticles was characterized by XRD, TEM, particle size analysis, N2 adsorption techniques. The surface modification of particles in order to perfect dispersion in polysulfone (PSf) matrix was performed by dimethyldichlorosilane (DMDCS) and aminopropyltrimethoxysilane (APTMS) as new modification agents. Thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and SEM analysis were applied to investigate thermal stability, glass transition temperature 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 MCM-41/PSf (20 wt.%) raised from 16 to 31.6, 0.47 to 0.99, 0.45 to 1.1 and 2.75 to 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 MCM-41/PSf (20 wt.%) enhanced to 29.12, 0.85, 0.85, 4.75, respectively, compared to neat PSf membrane. Using APTMS as modification agent resulted in higher selectivity of CO2/CH4 (44.23) and O2/N2 (7.77) 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.

► The DMDCS modified MCM-41 was synthesized and incorporated into PSF matrix to form a new nanocomposite membrane.
► The permeabilities of all gases tested such as CO2, N2, CH4 and O2 remarkably enhanced without decreasing selectivities of CO2/CH4 and O2/N2 compared to neat PSF membrane.
► The possible surface defects of nanocomposite membranes repaired by PDMS.
► The ideal selectivities of CO2/CH4 and O2/N2 of coated nanocomposite membranes increased with slight decrease in permeabilities of gases.
► The new coated nanocomposite membranes had superior permeability and selectivity of mentioned gases compared to neat PSF membrane.