Capacitive deionization technology in efficiently removing heavy metal ions and radionuclides from aqueous solutions

The rapid development of industrialization has led to the contamination of water with large amounts of metal ions and radionuclides, drawing global attention and concern. Developing sustainable, efficient, green, and lowcost water purification technologies is urgently needed. Capacitive deionization (CDI) is a promising water treatment technology for selectively separating or recovering various inorganic ions from wastewater, with the advantages of simple operation, energy saving, environmental protection, and easy recycling and regeneration. This review summarized the recent progress of CDI for the efficient removal of heavy metal ions and radionuclides from aqueous solution. First, a summary and introduction of the evolution of CDI structure, the characteristics of different CDI structure, and their applicable scenarios are presented. Next, a summary of the electrode materials used in CDI is provided, including carbon-based materials and Faradaic materials. The focus is on introducing the latest progress of CDI in the removal of heavy metal ions and radionuclides from aqueous solutions. Furthermore, the removal mechanism was discussed from spectroscopy characterization analysis and theoretical calculations. Finally, the challenges and prospects of CDI for removing heavy metal ions and radionuclides from aqueous solutions are discussed. The main focus is on the development of novel electrode materials, system integration and optimization, and coupling with other technologies. Valuable insights are provided for its application in the field of water purification.