Yiqun Liu

Novel organic–inorganic hybrid composite membranes for nanofiltration of acid and alkaline media

This study focuses on the development of novel organic–inorganic hybrid composite nanofiltration membranes based on poly(vinyl alcohol)-aminopropyl triethoxysilane (PVA-APES), which exhibit a rejection of 98.5% and a water flux of 13.5 L m−2 h−1 for a feed containing 2000 ppm Na2SO4 at 2.0 MPa at best-optimized aminopropyl triethoxysilane ratio and thermal cross-linking time. No irreversible changes in membrane performance have been observed after prolonged exposure (up to several weeks) of PVA-APES-1.0 membrane to the solutions with a pH in the range of 0–14. Moreover, after exposure to different acid solutions for 150 days, the Na2SO4 rejection of the composite membrane could still be maintained above 98%, and with an appropriate water flux. Notably, non-toxic solvent is used during the membrane preparation, showing enough green chemistry technology for environmental protection. A combination of high salt rejection, appropriate water flux, improved acid/alkali stability and environmentally friendly producing route indicates that these PVA-APES-xx membranes may be good candidate materials for nanofiltration in treating industrial wastewater at extreme pH values.