Efficient removal of cobalt ions by capacitive deionization using an asymmetric electrode

Abstract

Water pollution by metals is increasing. An electrode material, copper hexacyanoferrate (CuHCF), for capacitive deionization (CDI) to remove Co²⁺ from wastewater was developed. The asymmetric electrode structure of the CDI overcomes the limitations of traditional activated carbon electrodes (low ion removal capacity, ion removal rate, and charge efficiency). The specific capacitance of the CuHCF electrode (216.7 F g⁻¹) at 1 mV s⁻¹ was higher than that of a traditional electrode (92.0 F g⁻¹), and its deionization capacity was 156.85 mg g⁻¹ in 50 mg L⁻¹ aqueous Co²⁺ (charge efficiency = 68.4%). CuHCF is a high-performance electrode material for wastewater remediation.