Macromolecule crosslinked composite PVA membranes for pervaporation desalination

Pervaporation (PV) has shown great potential in desalination. Polyvinyl alcohol (PVA) is a widely used material for PV membranes. In the present work, hydrophilic composite membranes for PV desalination were prepared by coating mix solutions of PVA and Poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) on porous polyvinylidene fluoride (PVDF) supports. PMVE-MA, which serves as a macromolecular crosslinker, is well-compatible with PVA. The methyl ether groups in PMVE-MA also endow the crosslinked membrane to maintain good hydrophilicity. To achieve better performance, influences of the PVA concentration, the mass ratio of PVA to PMVE-MA, the crosslinking temperature and time, and the PVDF support on the desalination performance of the composite PV membrane were studied. At optimal conditions, a PVA-(PMVE-MA)/PVDF membrane was prepared. The membrane had a water flux of up to 45 kg·m−2·h−1 for the feed of 3.5 wt% NaCl solution at 50 °C (92 kg·m−2·h−1 at 70 °C). The salt passage was at an extremely low level and the conductivity of the permeate was lower than 100 μs/cm. In addition, the membrane showed excellent antifouling performance. After 14 h desalination of a sodium alginate-containing feed, the flux can be fully recovered by flushing the membrane in situ. The PVA-(PMVE-MA)/PVDF composite membrane shows great potential in desalination applications.