SBIR Phase II: Novel cathode for long-cycling capacitive deionization

This Small Business Innovation Research (SBIR) Phase II project will demonstrate the use of a new carbon-based water treatment process to condition and soften hard water sources. Specifically, this treatment process uses functionalized porous carbon sheets and small applied electrical voltages (<1.2 V) to target (adsorb and desorb) salt molecules from hard water streams. In addition, this process is reversible, resulting in a carbon-based filter that can soften water streams without significant maintenance or upkeep and providing a water softening solution that does not add to the "throw-away" culture that is common to many water treatment devices. Importantly, no salt or chemical additives are needed for this softening technique, further limiting its environmental impact in comparison to conventional salt-based softeners, and the energy required for this separation may best the most efficient techniques in use today. The proposed process is called inverted capacitive deionization (i-CDI). In i-CDI, salt molecules are naturally attracted to the carbon electrode surfaces due to the creation of electrodes possessing significant surface charge in aqueous environments. Electrodes are then regenerated using a small voltage, matched to the surface chemistry of the functionalized carbon electrodes, and salt is concentrated into a discharge stream. Through this Phase II project, the i-CDI process will be demonstrated for water softening applications in both food & beverage and industrial environments. Currently, water softening in these industries is carried out through chemical treatments, ion exchange, or selective membranes. In this project, surface charged carbon electrodes will be used in "flow-through" cell modules to demonstrate preferential removal of calcium, magnesium, carbonate, and other hardness-causing ions to soften multiple hard water sources. Comparisons will be drawn between this new i-CDI technology and incumbent water treatment techniques to outline benefits towards equipment downtime, energy costs, and effectiveness of the separation. Liquid sampling and lifetime studies will be conducted to further prove the benefits of this membrane-free, salt-free system.