Development of solvent resistant nanofiltration membranes (SRNF)

Master/bachelor assignment

Membrane technology has proven to be a promising alternative for molecular separation, more specifically for nanofiltration (NF). Presently great interest in NF is being devoted to the filtration of organic solvents. However, the lack of stable solvent resistant membranes has hampered their implementation for non-aqueous separations. The main challenge for further expansion of SRNF membranes thus remains the development of new membranes that are stable in a wide range of organic solvents and/or pH values, as well as, showing high and reproducible long term performances.

The aim of this project is to develop a class of ceramic-supported polymer (CSP) membranes that combines the advantages of both ceramic and polymeric membranes. These membranes should present high chemical, thermal and mechanical stability, as well as a MWCO bellow 500 Da. To achieve these demands the pores of a ceramic support will be grafted (covalent bonded) with suitable polymeric materials (e.g polysiloxanes, polyimides, polyamides, polysulfones, etc.) by graft polymerization (Fig. 1a) or polymer grafting (Fig. 1b). The desired surface properties (e.g. selectivity) will be engineered through suitable synthetic routes. By tuning the pore size and pore structure of the ceramic support, as well as varying the chemistry of the organic/polymeric layer (hydrophobicity, surface charge and surface tension) a tailor-made system for solvent resistant nanofiltration membranes is achieved

Fig. 1: (a) Monomer addition to a growing chain
(graft polymerization); (b) Attachment of a growing chain from the bulk to the surface (polymer grafting)

Fig. 2: Schematic representation of the attachment of a polymer-silane molecule to a silicon oxide surface

Besides the development of new membrane materials, nanofiltration properties will be evaluated, like:

·

permeability of several organic solvents

·

retention properties of different dyes or polymers

·

MWCO (molecular weight cut-off)

The project will be done at the Inorganic Membranes Group of the University of Twente. Membrane testing can also, eventually, be performed at facilities of one of the industrial partners in this project.

Assignments can be performed in the field of organic/inorganic chemistry/ materials science as well as in physical transport phenomena.

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