Particle size distribution influence on capacitive deionization: Insights for electrode preparation

As freshwater shortage has become a global issue, water desalination technique is of great importance to meet the increasing demand for freshwater resources of human beings. Capacitive deionization (CDI) has attracted significant attention in the current desalination technology portfolio. This is because of the use of low-cost electrode materials and the promise of high energy efficiency when including the energy recovery process. CDI, which has its advantage for applying low ionic strength by using various materials, has been explored to improve the system's performance. However, very few have addressed the importance of proper parameter designs, especially the electrodes. In our work, the same activated carbon of different average particle sizes has been studied by applying different desalination parameters (flow rate, holding time, salt concentrations). Our data show that larger particles limit intraparticle ion transportation because of the increased diffusion path length. We also see that a higher packing density, often favored by smaller particles or distribution of particle sizes, is detrimental to interparticle ion transportation. Our work addressed the importance of proper electrode and desalination parameter design for higher desalination performances.