High-flux and anti-fouling cellulose nanofiltration membranes prepared via phase inversion with ionic liquid as solvent

It is well-known that cellulose is difficult to dissolve in common organic solvent and be directly processed into porous membrane. In this work, using ionic liquid, 1-allyl-3-methylimidazolium chloride (AMIMCl) as solvent, high flux and anti-fouling cellulose nanofiltration (NF) membranes were fabricated by phase inversion method from 8.0 wt.% of cellulose/AMIMCl solutions. Pure water was employed as the non-solvent in phase inversion process. From the result of polarized light microscopy, we found that cellulose was completely dissolved in the AMIMCl at 90 degrees C. The characterizations of Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopies showed that no obvious changes occurred in the chemical structure of cellulose after membrane formation, but the crystallinity had a remarkable decreased. Membrane morphologies of the fabricated cellulose membranes including the cross-section and the surface were analyzed by scanning electron microscopy (SEM). It was found that the AMIMCl had a distinctive effect on phase inversion process and the cellulose selective layer displayed a macrovoid-free and relatively dense layered structure. Based on the filtration experimental results, the pure water permeation flux of the membranes reached 128.5 L/m(2)h under 0.4 MPa, and the molecular weight cut-off was less than 700 Da. The membranes exhibited a good stability and anti-fouling ability in water-phase separation process, and were suitable as NF membranes to separate the organic compounds with a medium molecular weight. (C) 2011 Elsevier B.V. All rights reserved.