A capacitive deionization cell designed with symmetric activated carbon electrodes was demonstrated to be able to successfully reduce wastewater Pb2+ concentrations to below the 5 ppm statuary limited for discharge into public sewers. The investigation found that the removal efficiency shows a maximum of 98% with an initial Pb2+ concentration of 100 ppm under an optimized voltage of 1.3 V. Although the reversibility of the process was poor during the first charge/discharge cycle, in part due to cathodic electrodeposition of lead hydroxycarbonates, this was improved by acidification of the electrolyte and subsequent cycles showed good reversibility. Finally, it was demonstrated that Na+ ions, with 50% removal efficiency and 100% reversibility, do not interfere with either the removal rate of Pb2+ ions or the reversibility of this process, providing a new angle on desalination applications for the system.
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