(219f) Polyelectrolyte Functionalized Membranes for Tunable Separations and Enzyme Reactions

The development of separation and greener chemical synthesis processes with reduced energy consumption and minimal environmental impact is critical for sustainable operation. Membrane processes are finding wide applications ranging from water treatment to reactors to advanced bio-separations. The development of bioinspired, tunable, nanocomposite membranes provide added opportunities in permeate flux and separation selectivity control. Depending on the types of functionalized groups (such as, chain length, charge of groups, biomolecule, etc.), these membranes could be used in applications ranging from metal (or oxyanions) separation to enzymatic catalysis. These membranes (with functionalized polypeptides or other polyelectrolytes) are also used for obtaining nanofiltration type separations stimuli responsive (pH and temperature). For example, we have demonstrated 90 % separations of arsenic oxyanions with high water flux at pressure of about 1 bar. By taking advantage of helix-coil transitions one can get tunable separations by altering pH. In addition, electrostatic self assembly in pores (layer-by-layer, LbL) can also be achieved through alternate adsorption of cationic and anionic poly-aminoacids or polyelectrolytes under convective flow conditions. Non-stoichiometric immobilization of charged multilayers within a confined pore geometry leads to an enhanced volume density of ionizable groups in the membrane phase leading highly tunable separations. Multilayer assemblies of polyelectrolytes provide excellent platform for protein/enzyme immobilization by providing reusability and high reactivity. Our results with Glucose oxidase enzyme with glucose as substrate showed very high (70 to 80% of homogeneous activity) activity, and continuous synthesis of hydrogen peroxide and gluconic acid. The presentation will include the role of nano-domain interactions for selective separations, polypeptide/polyelectrolyte assembly in membrane pores, and enzyme reactions for chemical synthesis and water applications. This research is supported by NSF KY EPSCoR program and by NIH-NIEHS-SRC.