Removal of ionic substances from dilute solution using activated carbon electrodes

Removal of various electrolytes from aqueous solution and a recycling operation were carried out using a flow-through capacitor. The amount of ions removed corresponds to the surface area and especially the micropore volume of the activated carbon electrode. Introduction of acidic functional groups on the surface of the carbon promoted ion removal (i.e. increase in rate and capacity), but there is a limit to the amount of functional groups that can be introduced with good effect. The adsorption-desorption properties of various alkali, alkaline earth and heavy metal sulfates were investigated. It was found that removal characteristics were different for the different types of ions. Depletion of the electrode also differed depending on the electrolyte that was removed. When copper and zinc ions were removed, the surface area of the cathode was reduced by a small amount. (C) 2003 Elsevier Science Ltd. All rights reserved.