Development of an Ion Removal Technique Based on Capacitive Deionization for Treatment of Rinse Water from Incineration Ash

Abstract

Capacitive deionization technique having higher efficiency and lower operation cost in comparison with the reverse osmosis technique for regeneration of rinse water used for dechlorination of incineration ashes is investigated. Activated charcoal-based electrodes were developed and characterized for their capacity to remove the chlorine ions dissolved in rinse water for incineration ashes. The mass ratio of rinse water to incineration ashes was also investigated to realize the most efficient removal of chloride from rinse water and minimize the regeneration load of the rinse water. The electrochemical properties of the developed electrode were characterized using a three-electrode cyclic voltammetry system, which showed that chemically modified carbon electrodes demonstrated an increase in capacitance. An asymmetrical distribution of capacities of both electrodes was found to be ideal wherein no electrochemical reactions took place at the electrode surface. The electrode capacities were defined based on the difference between the rest potential of the electrodes and the oxidation-reduction potential of the solution. Furthermore, the ion removal capacity of the electrode was evaluated using NaCl solution with a conductivity of 11 mS/cm. The electrode with a thickness ratio of 2.5:1 (anode:cathode) exhibited high ion removal capacity up to 0.034 mol/m 2 .

Maximizing Volumetric Removal Capacity in Capacitive Deionization by Adjusting Electrode Thickness and Charging Mode

“…2A shows, the highest values of specific capacitance in F and F • m −2 were found when thick electrodes were employed (180 μm). An important increment of the specific capacitance values with the increase of the electrode thickness was also observed by Andres et al 39 when cyclic voltammetry experiments were performed using carbon electrodes of five different thicknesses. In addition, this result is also in accordance with previous CDI and MCDI reports [36][37][38]40,45 in which the increase of the mass loading led to a higher removal of ions and consequently to a larger capacity of storing ions in the electrical double layer.…”

“…[33][34][35] In this sense, previous studies have analyzed the effect of the electrode thickness in the rate capability of EDLC's. 33 Nevertheless, as far as the authors know, previous studies in CDI based on modifying the electrode thickness [36][37][38][39][40] have not employed the time constant approach as a way of optimizing the CDI process.…”