Cosolvent-Driven Interfacial Polymerization for Superior Separation Performance of Polyurea-Based Pervaporation Membrane

Abstract

A thin-film composite (TFC) polyurea membrane was fabricated for the dehydration of an aqueous tetrahydrofuran (THF) solution through interfacial polymerization, wherein polyethyleneimine (a water-soluble amine monomer) and m-xylene diisocyanate (an oil-soluble diisocyanate monomer) were reacted on the surface of a modified polyacrylonitrile (mPAN) substrate. Cosolvents were used to tailor the membrane properties and increase the membrane permeation flux. Four types of alcohols that differed in the number of carbon (methanol, ethanol, isopropanol, and tert-butanol) were added as cosolvents, serving as swelling agents, to the aqueous-phase monomer solution, and their effect on the membrane properties and pervaporation separation was discussed. Attenuated total reflection Fourier transform infrared spectroscopy confirmed the formation of a polyurea layer on mPAN. Field emission scanning electron microscopy and surface water contact angle analysis indicated no change in the membrane morphology and hydrophilicity, respectively, despite the addition of cosolvents for interfacial polymerization. The TFC membrane produced when ethanol was the cosolvent exhibited the highest separation performance (permeation flux = 1006 ± 103 g·m−2·h−1; water concentration in permeate = 98.8 ± 0.3 wt.%) for an aqueous feed solution containing 90 wt.% THF at 25 °C. During the membrane formation, ethanol caused the polyurea layer to loosen and to acquire a certain degree of cross-linking. The optimal fabrication conditions were as follows: 10 wt.% ethanol as cosolvent; membrane curing temperature = 50 °C; membrane curing time = 30 min.

Research progress on extraction technology and biomedical function of natural sugar substitutes

“…As a new method, this technology confers various advantages during extraction of NSS, energy saving, high single-stage separation efficiency, environmental protection, no phase change, and a simple filtration process, among others (55). At present, a variety of membrane separation and extraction processes, such as ultrafiltration (UF), nanofiltration, electrodialysis, pervaporation and gas separation have been developed (56)(57)(58)(59)(60). Firstly, processes for separation and purification of alkaloids are greatly constrained by various challenges, including high pollution, high energy consumption and low continuity.…”

Vacuum-Assisted Interfacial Polymerization Technique for Enhanced Pervaporation Separation Performance of Thin-Film Composite Membranes

“…Porous modified PAN support was prepared similar to our previous work [ 35 ]. A polymeric solution of 15 wt% PAN in NMP was casted into a glass plate covered with nonwoven polyester using a casting knife with a gap of 200 μm.…”