Exploring the applicability of a combined electrodialysis/electro-oxidation cell for the degradation of 2,4-dichlorophenoxyacetic acid

Abstract

The improvement in the treatment efficiency of diluted effluents is one of the great challenges faced by electrochemical technology nowadays. In the present work, it is aimed to develop an electrochemical cell for the simultaneous concentration and degradation of ionic organic pollutants. This combined cell (so called EDEO device) integrates the concentration of the organic by electrodialysis (ED) with its electrooxidation (EO). For the particular case of the 2,4-dichlorophenoxyacetic acid (2,4-D), the performance of the cell has been tested with two anode materials (boron-doped diamond, BDD and mixed mineral oxides, MMO) and with two supporting electrolytes in order to explore four combinations that are expected to cover a wide range of possible actual scenarios. Results demonstrate that the combined EDEO process exhibits a degradation rate and a mineralization current efficiency markedly higher than the equivalent EO device when working with MMO anodes, either with NaCl or with Na2SO4. It was checked that the use of a BDD anode clearly increases the efficiency and the rate of the treatment due to the formation of strong oxidants. In this case, the effect of working with the combined EDEO in the rate of 2,4-D degradation is negligible because the 2,4-D transport rate becomes comparable to the degradation rate, being the combined process unable to generate a concentration greater than that accounted in the single EO device.

Improvement of electrochemical oxidation efficiency through combination with adsorption processes

“…To do this, different strategies have been evaluated such as coupling UV light irradiation (Cotillas et al, 2020;Rubí-Juárez et al, 2016) or ultrasounds waves (Cotillas et al, 2016;Dionisio et al, 2019; Martín de Vidales et al, 2019;Martín de Vidales et al, 2013;Sáez et al, 2011;Vidales et al, 2014) with electrochemical system to promote the formation and activation of oxidants and free radical in the bulk and, thus, to improve the mass transfer of pollutants to the electrode surface, respectively. Additionally, the search of synergisms of anodic and cathodic reactions has been also studied (Llanos et al, 2014;Llanos et al, 2018).…”

Management of solar energy to power electrochemical wastewater treatments

“…In contrast to that, at low contaminant concentrations and high current density values, the organic matter concentration drops exponentially, because of mass-transport limitations and side reactions of oxygen evolution. Furthermore, it is claimed that the remediation of concentrated wastewater effluents requires lower specific power consumptions [76,77].…”

A comparison of the electrolysis of soil washing wastes with active and non-active electrodes

“…The fitting of electrolytic results to first order kinetic indicates that it is important to obtain wastes as much concentrated as possible. For this reason, concentration techniques such as those recently proposed in works of our group for these pollutants can be of extreme significance for the development of successful treatments Raschitor et al, 2017;Llanos et al, 2018). A very important point when comparing the anodic oxidation of pollutants with different electrodes is the production of oxidants.…”