Desalination with porous electrodes : Mechanisms of ion transport and adsorption

Abstract

Capacitive deionization (CDI) is an electrochemical technology to adsorb ions from solution by alternately charging and discharging two porous electrodes. During charging, a voltage is applied between the electrodes, and ions are adsorbed into electrical double layers (EDLs) formed in the micropores of the electrode. As a result, feed water is desalinated. After the electrodes are saturated with salt, they are discharged and ions are released, resulting in a concentrated effluent stream. Recently there has been an growing scientific and commercial interest in CDI technology, and various applications are considered, such as wastewater remediation for cooling towers, water softening, and desalination of brackish water. In this Thesis we study mechanisms of ion transport and adsorption in CDI technology, and we address three topics: I) energy consumption and resistance identification, II) ion-selective adsorption, and III) long-term operation and pH changes.