Ion exchange membranes

Novel multilayered polymer membranes for commodity chemical production using bioelectrochemical systems.

Industrial wastewater can be used as a renewable resource for generating commodity products such as hydrogen peroxide. Hydrogen peroxide is a valuable chemical that is used as a strong oxidant with industrial applications in pulp and paper bleaching, chemical syntheses and textile bleaching. Bio-electrochemical systems can utilize wastewater to generate electrons through the microbial oxidation of organic matter. Generated electrons are transferred to the anode, transported to the cathode via an electrical circuit and consumed in the cathode reaction.         

Electroneutrality is maintained through transport of cations through a cation exchange membrane.

As bio-electrochemical processes require lower current densities than conventional electrochemical systems, lower ionic conductivity membranes are required. Current high performance membranes are expensive and not cost effective for such systems. As such, new membranes are desired which have adequate ionic conductivity (much lower than for fuel cells), but can be produced at very low costs (a few $USD/m2). 

A suitable ion exchange membrane must be stable under harsh conditions on the cathode side of the membrane. For long term performance and to ensure unimpeded processes at the cathode, the membrane should be highly monovalent ion selective, preferentially transporting the dominant monovalent ions in the wastewater feed (H+, K+ and Na+), while rejecting multivalent cations such as Ca2+ and Fe2+/3+, which can rapidly precipitate and cause fouling on the cathode side of the membrane.

 Researchers: Rebecca Yee, Kaisong Zhang and Bradley Ladewig