Large capacity and rapid rate of ion removal from synthetic municipal wastewater via CDI using chitosan-based nitrogen-doped porous carbon electrode

Abstract

Capacitive deionization (CDI) technology has excelled in water treatment areas such as brackish water desalination, hard water softening and pollution ion removal. However, the poor performance of the electrodes used in CDI cell construction continues to limit its practical application. In this work, we used chitosan mixed with potassium hydroxide (KOH) and simply carbonized to synthesize porous carbon electrode materials (CTS-850) with excellent material and electrochemical performance, and achieve high adsorption capacity and fast adsorption rate in a variety of salt solutions. The material characterization of CTS-850 displayed super large specific surface area (>2300 cm3 g−1), pore volume and excellent nitrogen doping. Electrochemical characterization showed excellent specific capacitance, good conductivity and cycle performance. In CDI experiments, we explored the removal efficiency of electrodes carbonized under different temperatures in single and mixed solution systems, and the CTS-850 electrode had an ultra-high adsorption capacity of 47 mg g-1 and a fast adsorption rate of 6.7 mg g-1 min-1 in 15 mM synthetic municipal wastewater (～1750 mg L-1). In addition, we discussed the relationship between high adsorption capacity, fast adsorption rate and material properties. Our work is expected to provide guidance for the synthesis of higher performance CDI electrode materials.