Abstract
The removal of electrolytes from aqueous solution and regeneration operation of electrodes was carried out using a flow through capacitor. The surface area and micropore volume of activated carbon electrode contributed to the amount of removed electrolytes. Introduction of surface acidic functional groups on the electrode promoted the removal (rate and capacity) remarkably, but the amount of functional groups had restriction. The adsorption-desorption property of many different sorts of electrolytes was divided into alkali, alkaline earth and transition metal.
On the other hand, based on the above results, we attemped to prepare electrodes of electric double layer capacitor to increase capacity. In the case of the aqueous electrolyte, the electric capacity depended more on oxygen functional groups than on BET surface area. A maximum of 30% increase in electric capacity was obtained by using ACFs with different amount of oxygen functional groups between the positive electrode and the negative one. It was attributed to that a certain number of functional group promotes not only the wettability of electrodes but also the negative charge of electrodes leading to an increase in capacity. Also, the characteristics of the electrodes after 30000 cycle charge-discharge were determined to confirm the reliability in an extended cycle operation.
