Preparation and application of reduced graphene oxide as the conductive material for capacitive deionization

This paper reports the effect of adding reduced graphene oxide (RGO) as a conductive material to the composition of an electrode for capacitive deionization (CDI), a process to remove salt from water using ionic adsorption and desorption driven by external applied voltage. RGO can be synthesized in an inexpensive way by the reduction and exfoliation of GO, and removing the oxygen-containing groups and recovering a conjugated structure. GO powder can be obtained from the modification of Hummers method and reduced into RGO using a thermal method. The physical and electrochemical characteristics of RGO material were evaluated and its desalination performance was tested with a CDI unit cell with a potentiostat and conductivity meter, by varying the applied voltage and feed rate of the salt solution. The performance of RGO was compared to graphite as a conductive material in a CDI electrode. The result showed RGO can increase the capacitance, reduce the equivalent series resistance, and improve the electrosorption capacity of CDI electrode.