Enhanced Capacitive Deionization by Dispersion of CNTs in Activated Carbon Electrode

Abstract

Energy-effective, ecofriendly desalination is a technology in universal demand due to global water scarcity. Capacitive deionization (CDI) is a promising method that has those advantages, but it is still necessary to enhance desalination performance to desalinate high-concentration raw salt water. In this work, carbon nanotubes (CNTs) are used as a conductive agent of the CDI electrode. To use CNTs as a conductive agent, we examine the effect of the dispersion status of the CNTs within activated carbon active material on the CDI performance. Acid treatment-functionalization of CNTs created a better dispersion status than CNTs without any treatment. Homogeneously dispersed CNTs showed enhanced electrochemical and desalination performance. Interestingly, desalination tests with highly concentrated raw salt water achieved a more notable improvement with 13.9% at only 1 wt % of CNT dispersion. The improvement mechanisms with dispersing CNTs such as increment of surface area and decrement of electrode resistivity are analyzed.