Now in a new study, researchers from Stanford University and Lawrence Livermore National Laboratory (LLNL), both located near San Francisco, California, US, have redesigned the architecture of the typical CD system and demonstrated a desalination rate that is 4-10 times faster and a salt concentration reduction that is 3-4 times higher per charge compared with typical CD systems. Their paper is accepted for publication in an upcoming issue of Energy & Environmental Science.
CD systems are most often designed so that the salty feed water flows between two porous electrodes, which the researchers call a “flow-between” CD system. By applying a voltage between the electrodes, ions in the feed water are removed and stored in the electric double layers (EDLs) in the micropores of the electrodes. Since opposite charges attract, the negatively charged chlorine anions are electrically adsorbed by the positively charged anode, while the positively charged sodium cations are pulled to the negatively charged cathode. When the electrodes become nearly full, water is pumped out of the system. New feed water is then introduced, and removing the voltage releases ions into a brine stream. These ions are then flushed out of the system and a new cycle can begin.