title: The transport behavior of As, Cu, Pb, and Zn during electrokinetic remediation of a contaminated soil using electrolyte conditioning.
abstract: Electrokinetic remediation (also known as electrokinetics) is a promising technology for removing metals from fine-grained soils. However, few studies have been conducted regarding the transport behavior of multi-metals during electrokinetics. We investigated the transport of As, Cu, Pb, and Zn from soils during electrokinetics, the metal fractionation before and after electrokinetics, the relationships between metal transport and fractionation, and the effects of electrolyte conditioning. The main transport mechanisms of the metals were electroosmosis and electromigration during the first two weeks and electromigration during the following weeks. The direction of electroosmotic flow was from the anode to the cathode, and the metals in the dissolved and reducible-oxides fractions were transported to the anode or cathode by electromigration according to the chemical speciation of the metal ions in the pore water. Moreover, a portion of the metals that were initially in the residual fraction transitioned to the reducible and soluble fractions during electrokinetic treatment. However, this alteration was slow and resulted in decreasing metal removal rates as the electrokinetic treatment progressed. In addition, the use of NaOH, H3PO4, and Na2SO4 as electrolytes resulted in conditions that favored the precipitation of metal hydroxides, phosphates, and sulfates in the soil. These results demonstrated that metal removal was affected by the initial metal fractionation, metal speciation in the pore solution, and the physical-chemical parameters of the electrolytes, such as pH and electrolyte composition. Therefore, the treatment time, use of chemicals, and energy consumption could be reduced by optimizing pretreatment and by choosing appropriate electrolytes for the target metals.
authors: Korea Institute of Science and Technology (KIST) - Gangneung Institute, Gangneung 210-340, Republic of Korea. Electronic address: inenviron@kist.re.kr.
authors: Jung-Seok
authors: JS
authors: Yang
authors: Korea Institute of Science and Technology (KIST) - Gangneung Institute, Gangneung 210-340, Republic of Korea.
authors: Man Jae
authors: MJ
authors: Kwon
authors: Korea Institute of Science and Technology (KIST) - Gangneung Institute, Gangneung 210-340, Republic of Korea.
authors: Jaeyoung
authors: J
authors: Choi
authors: Department of Environmental Engineering, Chonbuk National University, Deokjin-gu, Jeonju, Jeollabukdo 561-756, Republic of Korea.
authors: Kitae
authors: K
authors: Baek
authors: Biosciences Division, Argonne National Laboratory, Lemont, IL 60439, USA.
authors: Edward J
authors: EJ
authors: O'Loughlin
mesh_terms: D004566:Electrodes; D004573:Electrolytes; D004787:Environmental Pollution / Q000517:prevention & control*; D052918:Environmental Restoration and Remediation; D008670:Metals / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D008670:Metals; D012989:Soil Pollutants
keywords: Arsenic; Electrokinetics; Electromigration; Electroosmosis; Sequential extraction