Fabrication of high-performance PVA/PAN composite pervaporation membranes crosslinked by PMDA for wastewater desalination

The pyromellitic dianhydride (PMDA) crosslinked poly(vinyl alcohol) (PVA) was coated on top of the PAN ultrafiltration membrane to form a PVA/PAN composite PV membranes for wastewater desalination. The composite membranes have high application value in industrial wastewater treatment. By varying the membrane fabrication parameters including the weight percent (wt%) of the PMDA, the crosslink temperature and duration, membrane with the best desalination performance was obtained. The composite membrane with a 2-μm-thick PVA selective layer containing 20 wt% of PMDA and being crosslinked at 100 °C for 2 h showed the highest NaCl rejection of 99.98% with a water flux of 32.26 L/(m2 h) at 70 °C using the 35,000 ppm NaCl aqueous solution as feed. FTIR spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis and scanning electron microscope have been used to characterize the structures and properties of both the crosslinked PVA dense films and PVA/PAN composite membranes. The effects of the concentrations of PMDA, the crosslinking time and temperature to the membrane water contact angle, swelling degree, salt rejection and water flux were systematically studied.