Ultrafiltration (UF) with Ceramic Supported Polymeric Membranes

The ceramic-supported polymer (CSP) membrane is a composite ceramic-supported polymeric membrane where the surface chemistry is imparted by a terminally anchored polymer surface layer. The CSP membranes are being evaluated for use in selective removal of organics from aqueous systems. To date, ultrafiltration CSP membranes for treatment of oily wastes wastes and CSP pervaporation membrane for the removal of volatile organics from contaminated aqueous streams have been developed.

This research project focuses on the development of novel ceramic-supported polymer (CSP) membranes.  The synthesis of the hybrid ceramic-polymer membrane requires careful control of the polymer surface graft yield and the length of the resulting terminally anchored surface chains. This is achieved by careful surface activation and control of the graft polymerization reaction. To date, a prototype ultrafiltration CSP silica and zirconia-based membranes based on highly hydrophilic polyvinylpyrrolidone (PVP) have been prepared. These membranes are being evaluated for the treatment of oil-in-water emulsions in a cross-flow filtration mode. In this system, the hydrophilic PVP brush layer expands due to the affinity of the polymer for water (i.e., it is completely water soluble) while preferentially allowing the passage of water over oil. The tethered polymer chains have been shown to effectively screen surface hydroxyls and reduce adsorption of various organics onto the membrane surface. The resulting CSP membrane displays higher rejection (i.e.,  the membrane produced a permeate with a lower oil concentration relative to the unmodified membrane). At the same time, flux decline, which occurs with the unmodified membrane, is significantly reduced with the CSP membrane. These new types of fouling-resistant membranes have been shown to be particularly effective for the treatment of macro- down to nanoemulsions of oil-in-water. 

The zirconia-PVP membranes have also been evaluated for the ultrafiltration of proteins. The goal is to minimize protein adsorption onto the membrane surface and thereby improve membrane performance. Research, to date, revealed that the grafting of water soluble polymers onto zirconia and silica substrates is an effective approach to reducing protein adsorption. Studies with tubular silica-polymer CSP membranes demonstrated, for the first time, that CSP membranes can be utilized for protein ultrafiltration. The CSP membranes can be easily sterilized (as required in biomedical applications and food and beverage processing), without loss of performance, and therefore have a clear advantage over polymeric membranes.

Finally, we note that another unique attribute of the CSP membranes is the variation of hydrodynamic permeability in response to pore-wall shear rates. This hydrodyamic response of the CSP membrane opens the possibility for the synthesis of membranes in which the pores can act as hydrodynamic valves. This additional degree of freedom of operating the CSP membrane could find use in various biomedical applications.  

References:
Montserrat Rovira-Bru, Francesc Giralt and Yoram Cohen, Adsorption of Lysozyme onto Zirconia Modified with Terminally Grafted Polyvinylpyrrolidone , J. Colloid and Interface Science, in press.

Castro, Robert P., Harold G. Monbouquette and Yoram Cohen, "Shear-induced permeability changes in a polymer grafted silica membrane," J. Membrane Sci., 179, 207-220 (2000).

Faibish R., Menachem Elimelech and Y. Cohen, "Effect of Intraparticle Electrostatic Double Layer Interactions on Permeate Flux Decline in Crossflow Membrane Filtration of Colloidal Suspensions: An Experimental Investigation", J. Colloid and Interface Science, 204, 77-86 (1998).

Castro, R. P., H. G. Monbouquette and Y. Cohen, "Polyvinylpyrrolidone-Silica Membranes for the Treatment of Oil-in-Water Emulsions"," J. Membrane Science, 115, 179-187 (1996).

Castro, R., H. Monbouquette, and Y. Cohen and R. Castro, "The Permeability of Surface Modified Porous Silica Membranes," Journal Membrane Science, 84, 151-160 (1993).

Last update:

10/24/2004