Ex-Situ Characterization of Carbon Slurries for the Flow-Electrode Capacitive Desalination

Seawater desalination has great potential to meet the increasing global demand for freshwater. We are studying and developing a relatively new technology for desalination termed flow-electrode capacitive deionization (FCDI). FCDI cell design represents a significant development over standard capacitive deionization (CDI) cell by achieving continuous operation and the ability to process high salinity streams. These systems replace porous carbon-based solid electrodes with conductive carbon particles suspended in a continuously circulated electrolyte. We will present a study of the properties and chemistry of various carbon-based slurries. Particle type, size, shape, mass loading, and surface chemistry all play an important role in FCDI cells. Also important is the coupling among transport, charge exchange, and solution chemistry. We have developed an ex-situ experimental setup to quantify the charge transfer ability of carbon slurries, including carbon black and activated carbon. This ex-situ system enables convenient measurement of charge transport as a function of slurry properties and mixing. Our preliminary results suggest that the transport features, particle type, size, shape, and chemistry play a significant role in the charge transfer ability of the slurry.