High-Performance Capacitive Deionization of Copper Ions at Nanoporous ZnS-Decorated Carbon Felt

Extraction of dilute copper ions from wastewater is of great importance for simultaneous remediation of heavy-metal pollution and recovery of valuable metals. In this study, an efficient and selective method for copper recovery using capacitive deionization on ZnS-decorated carbon felt electrodes was developed and found suitable for use in HCl electrolytes. With the introduction of ZnS, the modified electrode exhibited a nanoporous structure with enhanced electrochemical capacitance, increased surface area and improved wettability. As a result, the copper ions were successfully removed via electrostatic interactions at low voltages of -0.2 V, in which the removal capacity of 27.4 mg.g(-1) is much better than the corresponding ones of FeS-decorated (18 mg.g(-1)) and pristine (12 mg.g(-1)) carbon felts. In addition to improved performance, enhanced adsorption-desorption stability and selectivity were observed during long-term tests in the presence of co-existing metallic ions and natural organic matter, offering promising potential as an alternative metal recycling and water purification technique. (C) 2019 The Electrochemical Society