Performance Of Foamed Nickel/activated Carbon Electrode On Capacitive Deionization For Water Treatment

Capacitive deionization(CDI), also known as electric-adsorption technology, is a clean, environmental friendly method for removing salt from aqueous solution based on the electrostatic adsorption principle. Compared with other traditional desalination technologies, such as electrodialysis, reverse osmosis and ion exchange, CDI is characterized by the high energy efficiency, easy electrode regeneration and low cost.Moreover CDI technology has shown a wide application prospects in water treatment filed, not only applied to desalination, but also dyeing wastewater purification, the special drinking water treatment, industrial water softening as well as preparation of high-purity water. Currently, the majority of research is focused on the high-performance electrode materials used for CDI. This paper carried out the research of carbon electrodes which is suitable for CDI, in order to obtain the electrodes which has extensive material sources, excellent performance and is easy to realize. It has great theoretical and practical significance to develop the spread the CDI technology.In this paper, the foamed nickel/activated carbon electrode applied in CDI was fabricated by the method of preparation supercapacitor electrode and the low price of activated carbon with excellent performance was used as the main electrode material. The CDI module was constructed with the prepared electrodes and then the experimental system was constituted. The different factors such as voltage, flow rate, initial concentration ware investigated and the effects of factors on electro-adsorption experiment were studied. Besides, the relationship between the initial concentrations and saturated electro-adsorption capacity was established and operating condition was optimized to realize the good capability of desalination.The activated carbon was modified by the KOH and HNO3 to improve the physical structure characteristics and surface chemical properties, respectively. Modified activated carbons were prepared KOH-AC, HNO3-AC electrodes and then the CDI systems were consisted for the experiment. Moreover, the effects of the operating conditions have been studied to optimize the electro-adsorption test results. The consecutive electro-adsorption/electro-desorption cycle figure clearly indicates that AC, KOH-AC, HNO3-AC electrodes have the good properties of regeneration and the KOH-AC, HNO3-AC electrodes have a shorter cycle times than the AC electrode’s. Activated carbon electrode has the most electro-adsorption capacity with KOH modified under the same condition.This study has concluded that the activated carbon with KOH modified have a higher specific surface area and larger quantity of mesoporous. Therefore, the charge efficiency and the electro-adsorption capacity were increased with the suitable physical structure characteristics for CDI. Otherwise, the activated carbon modified by HNO3 has increased the surface functional groups and enhanced the hydrophilicity on the surface of the electrode. The results also suggest that the charge efficiency and the electro-adsorption capacity are improved. So the two different modification methods have heightened the physical structure characteristics and surface chemical properties of the activated carbon electrode, which is applicable to CDI.