NAMS 2002 Workshop - ICOM 2008

Membrane and Surface Modification III – 3
Friday July 18, 10:45 AM-11:15 AM, Honolulu/Kahuku
Solvent Resistant Nanofiltration with Partially Hydrolyzed Asymmetric
Polyacrylonitrile Membranes
P. Vandezande (Speaker), Center for Surface Chemistry and Catalysis, Katholieke Univ. Leuven,
Belgium
X. Li, Center for Surface Chemistry and Catalysis, Katholieke Univ. Leuven, Belgium
K. Vanderschoot, Centre Center for Surface Chemistry and Catalysis, Katholieke Univ. Leuven,
Belgium
I. Willems, Center for Surface Chemistry and Catalysis, Katholieke Univ. Leuven, Belgium
I. Vankelecom, Center for Surface Chemistry and Catalysis, Katholieke Univ. Leuven, Belgium -
ivo.vankelecom@biw.kuleuven.be
Over the last few years, new technical achievements and a growing acceptance
of membrane technology in industry have increased interest in membranes to
separate non-aqueous streams. Particularly solvent resistant nanofiltration
(SRNF), where organic mixtures are separated on a molecular level by simply
applying a pressure gradient, has experienced a significant growth, spurred by
increasing environmental concerns and energy prices [1]. Offering a sustainable
alternative for traditional separation techniques, SRNF holds a vast potential in a
vraiety of solvent-intensive processes were low molecular weight compounds
(typically 200-1000 g/mol) are to be separated from organic solvents. Such
applications are mainly found in the food, fine-chemical, pharmaceutical and
petrochemical industries.
In SRNF, an ideal membrane combines chemical, mechanical and thermal
stability with excellent rejections and high permeabilities. Unfortunately,
applications are yet difficult in certain demanding solvents such as the aprotic
solvents DMF, NMP, DMAc and DMSO, since none of the polymeric SRNF
membranes currently available on the market resists these solvents. Solute
recovery and solvent purification in industries that commonly use these aprotic
solvents therefore generally rely on conventional separation techniques such as
energy-consuming distillations or waste- generating extractions. The
development of SRNF membranes with a high flux and a low MWCO)in these
solvents can provide a sustainable alternative for these processes.
Since most polymers dissolve in aprotic solvents, the membrane-forming polymer
should be chosen so that it can be modified to be able to withstand these
solvents. Integrally skinned asymmetric polyimide membranes, prepared by
phase- inversion, have been chemically cross-linked with diamines to allow
applications in chemically rigorous environments, i.e. aprotic solvents and THF
[2,3].