Enhanced electrokinetic remediation of polluted soils by anolyte pH conditioning. (May 2018)

• Record Type: Journal Article
• Authors: López Vizcaíno, R.; Yustres, A.; Asensio, L.; Saez, C.; Cañizares, P.; Rodrigo, M.A.; Navarro, V.
• Is Part Of: Chemosphere. Volume 199(2018)
• Page Start: 477
• Page End: 485
• Publication Date: 2018-05
• Subjects: Electrokinetic soil remediation -- Multiphysics simulation -- Anolyte pH conditioning -- Pesticide -- M4EKR; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.02.038
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In the treatment of a polluted soil, the pH has a strong impact on the development of different physicochemical processes as precipitation/dissolution, adsorption/desorption or ionic exchange. In addition, the pH determines the chemical speciation of the compounds present in the system and, consequently, it conditions the transport processes by which those compounds will move. This question has aroused great interest in the development of pH control technologies coupled to soil remediation processes. In electrokinetic remediation processes, pH has usually been controlled by catholyte pH conditioning with acid solutions, applied to cases of heavy metals pollution. However, this method is not effective with pollutants that can be dissociated in anionic species. In this context, this paper presents a study of the electrokinetic remediation of soils polluted with 2, 4-Dichlorophenoxyacetic acid, a common polar pesticide, enhanced with an anolyte pH conditioning strategy. A numerical study is proposed to evaluate the effectiveness of the strategy. Several numerical tests have been carried out for NaOH solutions with different concentrations as pH conditioning fluid. The results show that the anolyte pH conditioning strategy makes it possible to control the pH of the soil and, consequently, the chemical speciation of pollutant species. Thus, it is possible to achieve an important flux of pesticide into the anolyte compartment (electro-migration of anionic species and diffusive transport of acid species). This way, it possible to maximise the pesticide accumulation in this compartment, allowing a much more effective removal of pollutants from the soil than without the anolyte pH conditioning strategy. Highlights: M4EKR, model for electrokinetic remediation of polluted soil with 2, 4-D, is presented. Benefits of the application of Anolyte-pH-conditioning strategy have been studied. NaOH solutions with different concentrations have been used as pH conditioning fluid. Anolyte-pH-conditioning allows to control soil pH and chemical speciation of 2, 4-D. Anolyte-pH-conditioning strategy maximizes the pesticide accumulation in anolyte.