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

Abstract

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-lm-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/(m 2 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.

Structures, Properties, and Performances—Relationships of Polymeric Membranes for Pervaporative Desalination

“…Again, the fabrication of a series of PVA-PAN-based composite membranes made of either PMDA or SSA crosslinked PVA coating on the top of the PAN UF membrane have also been reported [122,127]. The PAN support enhanced further mechanical stability to the PVA matrix crosslinked by hydrolyzed PMDA or SSA.…”

“…GO-incorporated CS-based MMMs were fabricated by such a popular technique [136], after the usual preparation of GO-nanosheets by the modified Hummers method [169]. While preparing the PVA-PAN composite membrane [127], initially, a PMDA-crosslinked dense film of PVA was prepared by solution-casting, followed by preparation of composite membrane by the dip-coating method. In this step, an alkali-treated hydrolyzed PAN membrane was dipped into a dope solution of PVA for 30 s, followed by the PVA-coated PAN membrane air drying for 48 h at room temperature, and subsequent heating to initiate crosslinking.…”

“…The morphological characteristics of PAN-PVA membranes (Figure 12i–l) [127] were composed of large finger-like micro-voids in the PAN portion underneath the skin layer of PVA. Such micro-voids were crucial in reducing the mass-transfer resistance against the water vapor during pervaporative desalination.…”

“…Similarly, crosslinking of O–H of PVA with MA in composite PVA membranes supported on PVS-based hollow fibers was realized from the loss of PVA-specific free O–H and –COOH of MA [114]. Condensation of –COOH of PMDA crosslinker and O–H of PVA in preparing the PVA-PAN composite membrane was detected from the continuous loss of intensity for O–H specific broad peak centered at 3320 cm −1 [178,179,180,181,182,183], along with the consequent gain in C=O and –C–O–C– peaks of aromatic ester at 1750 and 1275 cm −1 , respectively [127].…”

Synthesis of poly(4, 4′‐biphenylene sulfonyl succinamide)‐polysulfone blend membranes for removal of toxic metal ions from water

“…Among several polymers used for membrane fabrication, polysulfone‐based membranes are familiar for water purification and removal of toxic metal ions due to its attractive physico‐chemical and thermal properties. Various other bio and synthetic polymers including chitosan, cellulose acetate, poly(vinyl alcohol), poly acrylonitrile, polyamides, and polyurethane have also been used for membrane fabrication . Selection of suitable polymer for membrane fabrication plays a conspicuous role in enhancing the properties such as hydrophilicity, fouling resistance, high pore density, and high selectivity .…”