(575b) Electrosteric Stabilization and Covalent Functionalization of Iron Nanoparticles In a Mixed Matrix Membrane

There has been a growing interest in using iron-based nanoparticles in water treatment due to their catalytic properties. Monometallic and bimetallic iron nanoparticles are reactive in an aqueous system and can be designed for targeted removal of specific organic and inorganic water contaminants. Iron metal nanoparticles undergo surface oxidation through reactions with both water and oxygen and produce reactive species that are then utilized to oxidize or reduce a specific contaminant. Through the oxidation process, iron metal is oxidized to ferrous iron, which in turn can participate in the Fenton reactions and produce reactive oxygen species and hydroxyl radicals. Iron metal oxidation also produces hydrogen gas (through reaction with water), which can react with organic compounds through reduction reactions. The catalytic properties of iron nanoparticles can be enhanced through particle stabilization by organic chelating compounds and through secondary metal coatings. Both organic stabilizers and secondary metals (e.g., palladium, copper) affect the oxidation of the nanoparticles and ultimately, nanoparticle reactivity.

For reactive nanoparticles to be used in water treatment, the particles must be contained or immobilized within the treatment system. One potential method to contain the nanoparticles is to incorporate the particles into polymeric membranes; ideally, these mixed matrix membranes would be designed such that the membrane continues to function as a physical barrier to filtrants, while the reactive nanoparticles degrade or adsorb dissolved contaminants that typically pass through conventional membranes.

This research investigates the use of a bifunctional poly(ethylene glycol)-based polymer in iron nanoparticle functionalization and incorporation into a poly(ether sulfone) (PES) film.  The effect of covalent attachment of the polymer matrix to the iron nanoparticle on separation ability will be evaluated as a function of filtration performance in a dead-end permeation cell.  This mixed matrix film will be compared to a synthesized PES film where the iron nanoparticles are contained within the film by electrosteric stabilization.  Mixed matrix films will be characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and electron microscopy techniques.  The comparison between covalently-attached nanoparticles and nanoparticles sterically and electrostatically bound to the polymer matrix will provide insight as to how nanoparticle stabilization within a polymeric membrane affects membrane performance and nanoparticle dispersion within the film.