Chitosan-based activated carbon as economic and efficient sustainable material for capacitive deionization of low salinity water

Abstract

Capacitive deionization (CDI) is a novel low-energy green desalination technology that has attracted much attention in recent years, especially for the desalination of low salinity water. One of the key issues in CDI is the electrode materials, and many efforts have been devoted to developing materials with high specific surface areas, appropriate pore distributions, and good electronic conductivity, in order to obtain a high salt adsorption capacity. In this study, chitosan was selected as a precursor for the preparation of high-performance chitosan-based activated carbon (CTS-AC) for use in CDI electrodes via pyrolysis and KOH activation. The results show that CTS-AC800 (activated at 800 °C) has the largest BET specific surface area (2727 m² g⁻¹), and exhibits an appropriate pore size distribution (<10 nm), nitrogen doping (2.0%) and good electronic conductivity (2.09 S cm⁻¹). The CDI performance results show that the CTS-AC800 electrode has a saturated salt adsorption capacity of 14.12 mg g⁻¹ in a 500 mg L⁻¹ NaCl solution and retains 95% capacity after 150 adsorption–desorption cycles. Thus, chitosan is a promising, sustainable precursor for CDI electrode materials.