Nanofiltration in non-aqueous solutions by porous silica-zirconia membranes

Citation
T. Tsuru et al., Nanofiltration in non-aqueous solutions by porous silica-zirconia membranes, J MEMBR SCI, 185(2), 2001, pp. 253-261
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry,"Chemical Engineering
Journal title
JOURNAL OF MEMBRANE SCIENCE
ISSN journal
0376-7388 → ACNP
Volume
185
Issue
2
Year of publication
2001
Pages
253 - 261
Database
ISI
SICI code
0376-7388(20010430)185:2<253:NINSBP>2.0.ZU;2-H
Abstract
Porous membranes having various average pore sizes, ranging from 1 to 4 nm, were prepared from silica-zirconia composite colloidal sols by sol-gel pro cesses, and were used for nanofiltration (NF) experiments in non-aqueous so lutions of ethanol and methanol. Silica-zirconia membranes, which were test ed in pure alcohol solutions for the first time after the preparation of th e membrane, showed a gradual decrease in flux for approximately 100 h and t hen reached a steady flux. When the feed, after reaching the steady flux wi th ethanol, was changed to another alcohol, steady flux was attained after only several hours. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (PEG) of various molecular weights (PEG400, 600, 1000, and 2000) were nanofiltrated in methanol and ethanol solutions at 50 degre esC. Rejections in non-aqueous solutions increased with applied pressure, w hich is similar to aqueous solutions, Control of pore size of silica-zircon ia membranes showing molecular weight cut-offs in methanol solutions at 300 , 600, 1000, and >1000, respectively, was possible by the appropriate choic e of colloidal particle sizes. Rejection in methanal solution showed a tend ency similar to that in ethanol solution, while rejection in methanol was s lightly larger than in ethanol solutions. In addition, rejection in water w as much smaller than in methanol solution. For example, the rejection of PE G600 in water and methanol was 0.03 and 0.74, respectively. These results s uggest that solvent type plays an important role in determining rejection, ass result of the interaction with solvents and/or membrane surface. (C) 20 01 Elsevier Science B.V. All rights reserved.