Knowledge on nanofiltration membranes and their construction based on polyether sulfone and modified with silica and carbon nanofillers

Nanofiltration is a newer method of membrane filtration processes. This method is usually used to separate particles from waters that have small amounts of dissolved solids; such as surface water and fresh underground water. The purpose of this method is to remove polyvalent cations and to remove prefabricated disinfectants such as natural and synthetic organic materials. The application of nanofiltration in food industries such as dairy industries is expanding widely. In these industries, nanofiltration is used for the partial removal of minerals (monovalent ions). This study presents the preparation of hybrid nanofiltration membranes based on poly(۱,۴-phenylene ether ether sulfone), polyacrylonitrile, poly(vinyl pyrrolidone), and SBA-۱۵ mesoporous silica. Laser treatment of polymeric solutions to enhance the hydrophilicity and performance of membranes was investigated. The membranes’ structure was characterized using scanning electron (SEM) and atomic force (AFM) microscopy and contact angle measurements. The addition of PAN in the casting solution produced significant changes in the membrane structure, from finger-like porous structures to sponge-like porous structures. Increased PAN concentration in the membrane composition enhanced the hydrophilicity of the membrane surface, which also accounted for the improvement in the antifouling capabilities. The permeation of apple pomace extract and the content of polyphenols and flavonoids were used to evaluate the efficacy of the hybrid membranes created. The results showed that the hybrid nanofiltration membranes based on PPEES/PAN/PVP/SBA-۱۵: ۱۵/۵/۱/۱ and ۱۷/۳/۱/۱ exposed to laser for ۵ min present a higher rejection coefficient to total polyphenols (۷۸.۶ ± ۰.۷% and ۹۷.۸ ± ۰.۹%, respectively) and flavonoids (۲۸.۷ ± ۰.۲% and ۵۰.۳ ± ۰.۴%, respectively) and are substantially better than a commercial membrane with MWCO ۱۰۰۰ Da or PPEES-PVP-based membrane.