Polymer and Separations (PolySep) Research Laboratory

Last update:

01/04/2004

B.A.Sc, Chemical Engineering, Universitat Rovira i Virgili, Tarragona, Spain. Ph.D., (1999) Chemical Engineering, Universitat Rovira i Virgili, Tarragona, Spain.

Research Interests

• Adsorption of proteins on inorganic oxide surfaces
• Ultrafiltration of proteins using ceramic-supported polymer membranes

Abstract of Ph.D. Dissertation

Ceramic surfaces (SiO₂ and ZrO₂) were modified by growing of covalently-bonded polyvinylpyrrolidone (PVP) chains from the surface via a graft polymerization process. The resulting surfaces were effective in screening the hydroxyl groups on the original ceramic oxide surfaces, which are responsible for most interactions of Lysozyme with the surface. Thus, modified surfaces are expected to be less attractive to the components of a solution in contact with it.

Adsorption of LYS was found to be strongly inhibited on the PVP-grafted surface. The adsorption capacity was shown to be dependent on the PVP-grafted chains conformation and on the distance between anchored points. Higher protein rejection was obtained when the polymer chains were in the brush conformation, with a distance between chains smaller than the protein size. In this latter condition, penetration of the protein to into the polymer layer is hindered and the energetic requirement to displace the grafted polymer chains is prohibitive. 

The performance of PVP-grafted membranes was evaluated for protein fouling prevention during cross-flow filtration of protein solutions. The protective action of the polymer layer observed during static adsorption of protein also occurs here. Thus, lower adsorption on PVP-grafted membranes was observed and, as a consequence, flux decline due to protein adsorption was dramatically reduced. Good performance of PVP-grafted membranes is attributed not only to chemical properties of the PVP chains, but also to its conformation. i.e., effective performance of PVP-grafted membranes are attributable to the mobility of the grafted chains on the surface which prevents adsorption when the chains are subjected to shear flow.

Publications & Presentations

1. Cohen, Y., R. S. Faibish and M. Rovira-Bru, "Polymer-Modified Silica Resins for Aqueous Size Exclusion Chromatography," pp. 263-310, in Interfacial Phenomena in Chromatography, Pefferkorn, E. (Ed.), Marcel-Dekker, New York, (1999).
2. 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.
3. Rovira, M., F. Giralt and Y. Cohen, "Protein Fouling Reduction on ceramic Membranes via Graft Polymerization", AICHE Annual Meeting, Miami Beach, FL, November 15-20, 1998.

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Email:
Montse Rovira: montse@raviol.chem.purdue.edu