Novel polyether sulfone/polyethylenimine grafted nano-silica nanocomposite membranes: Interaction mechanism and ultrafiltration performance

In the current work, we report a novel low fouling mixed matrix membranes (MMMs) that comprise polyethylenimine coated silica nanoparticles (SiO2-g-PEI) and polyethersulfone membrane for Ultrafiltration application. The hydrophilic SiO2-g-PEI was synthesized via grafting polyethylenimine (PEI) molecules onto the surfaces of silica nanoparticles (SiO2 NPs). Later on, NPs were embedded within a PES polymeric matrix at disparate ratios by the phase inversion method to obtain modified MMMs. Modified SiO2-g-PEI were characterized by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy, whereas the MMMs were characterized via FE-SEM, EDX, FTIR-ATR, and contact angle (CA). Moreover, this study presents the proposed interaction mechanism between the contents of PES/SiO2-g-PEI and the interaction mechanism of each PES/SiO2-g-PEI membrane with molecules of water. Results disclosed that MMMs prepared with 0.7 wt% nanoadditives possessed optimum characteristics and performance with 82.56% surface porosity, 41 +/- 2 degrees CA, and higher mean pore size (41.04 nm). The pure water permeation permeability of this membrane showcased more than 7-fold enhancement with 97% retention to BSA if compared to pristine PES. Besides, the M0.7 manifested a stable performance during the prolonged operation, greater flux recovery ratio (94%) and was less prone to fouling by the protein solution. These results significantly override those obtained by pristine PES membrane and suggest a promising potential of SiO2-g-PEI on tailoring membrane performance.