Enhancing capacitive deionization technology as an effective method for water treatment using commercially available graphene

Abstract

In recent years, capacitive deionization (CDI) has been reported as one of the emerging technologies developed with the purpose of water desalination. This work is aimed at the integration of supercapacitor electrodes for efficient removal of ions from water, and thus to achieve an energy efficient, and cost-effective water treatment process. Our objective is to transfer the vast knowledge of supercapacitors and advanced materials in area of water treatment to enhance the knowledge of the CDI process. Towards the main purpose, graphene-based supercapacitor electrodes were developed from commercially available, cost-effective graphene and the use of these new materials for deionization was explored in detail. The porosity, morphology and electrochemical characteristics of the active materials were confirmed by Brunauer–Emmett–Teller method, scanning electron microscopy, Raman spectroscopy and chronoamperometry. Furthermore, the deionization performances of the graphene electrodes were evaluated by a laboratory scale CDI unit. The ion sorption behavior of the electrode was analyzed at different electrical potentials and flow rates. Impact of operating parameters on the sorption capacity was determined. At 20 mL/min flow rate and 2.0 V potential, the electrosorptive capacity of commercially available graphene electrodes could reach 12.5 μmol/g. Our results indicated the ability to use commercially available graphene for deionization purpose.