Competitive Adsorption in Capacitive Deionization

For water reclamation and for better water quality, development of advanced wastewater treatment technologies has been an important issue. Capacitive deionization (CDI) captures ions in the porous conductive materials and thus to removal ions from water. The captured ions can be released once the system is discharged. Compare to membrane filtration, CDI does not need power consumption to overcome osmotic pressure and does not have fouling problem. Therefore, CDI, which was originally developed to desalt sea and brackish waters, has also been found applications in wastewater treatment. The removal of ions is affected by hydration radius, valance, mobility, and concentration of ions. However, most of the studies investigated these factors separately; that is, there is only one ion in the system. Few literatures have pointed out that these factors may compete if there more than one ion in the system. Therefore, the objective of this study is to investigate the competition among hydration radius, valance, and concentration of ions when there are more than one ion in the CDI system. Alkali and Alkali earth element will be studied so that the results can be compared to the literatures. Also, removal of heavy metal ions (e.g., Pb, Cr, Cd, and Cu) via CDI will also be investigated. The results will not only provide understandings of the mixed-ion system, but will also help to explore application of CDI in wastewater treatment and water reclamation.