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Sun Z, Zhang C, Demarscho Eugene B, He X. Electroosmotic flow in soft clay and measures to promote movement under direct current electric field. PLoS One 2024; 19:e0302150. [PMID: 38625994 PMCID: PMC11020605 DOI: 10.1371/journal.pone.0302150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 03/28/2024] [Indexed: 04/18/2024] Open
Abstract
Electroosmosis has been proposed as a technique to reduce moisture and thus increase the stability of soft clay. However, its high energy consumption and uneven reinforcement effect has limited its popularization and application in practical engineering. This paper presents the results of some electrokinetic tests performed on clayey specimens with different electrification time and anode boundary conditions. The results indicate that the timing of the formation of electroosmotic flow (EF) by the water originally contained in different soil cross sections, from the anode to the cathode, varies. The measuring soil cross section nearest the anode first reached the limiting water content of 22%±3% and electroosmosis had to be stopped. Water injection into the anode during electroosmosis enhanced further drainage of other four measuring soil cross sections until the second soil cross section from the anode reached the limiting water content of 30%±2%. Electroosmosis with water injection into the anode technique provides more uniform reinforcement, increasing EF, and environmental protection. The experimental results highlighted the relevant and expected contribution of water injection into the anode on the effectiveness of the electroosmotic treatment as a soft clay improvement technique.
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Affiliation(s)
- Zhaohua Sun
- School of Transportation and Civil Engineering, Nantong University, Nantong, China
- Key Laboratory of New Technology for Construction of Cities in Mountain Area, Ministry of Education, Chongqing University, Chongqing, China
| | - Cheng Zhang
- School of Transportation and Civil Engineering, Nantong University, Nantong, China
| | | | - Xiwen He
- School of Transportation and Civil Engineering, Nantong University, Nantong, China
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Zheng F, Zhai Y, Yue W, Teng Y. Coupling flow and electric fields to simulate migration and remediation of uranium in groundwater remediated by electroosmosis and a permeable reactive bio-barrier. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 346:118947. [PMID: 37699289 DOI: 10.1016/j.jenvman.2023.118947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/16/2023] [Accepted: 09/06/2023] [Indexed: 09/14/2023]
Abstract
Combined remediation technologies are increasingly being considered to uranium contaminated groundwater, such as the joint utilize of permeable reactive bio-barrier (Bio-PRB) and electrokinetic remediation (EKR). While the assessment of uranium plume evolution in the combined remediation system (CRS) have often been impeded by insufficient understanding of multi-physical field superposition. Therefore, advanced knowledge in multi-physical field coupling in groundwater flow will be crucial to the practical application of these techniques. A two-dimensional multi-physical field coupling model was constructed for predicting the uranium degradation in CRS. The study demonstrates that the coupling model is able to predict the uranium plume evolution and rapidly evaluate the performance of CRS components. The results show that field electric direction and flow field strength are the key factors that affect the retardation and remediation performance of CRS. The reverse electric field direction significantly affected the contact reaction time of uranium in the system. The uranium residence time in the reverse electric field was 3.8 d, which was significantly greater than the original electric field (2.0 d). Depending on the voltage, the reverse electric field direction was 16%-36% more efficient than the original direction. The strength of the flow field was about two orders of magnitude higher than that of the electric field, so the groundwater flow rate dominated remediation efficiency. Reducing the flow rate by 1/2 could improve the performance of the system by approximately 66%. In addition, the coupling model can be utilized to design standard CRS for real site of uranium contaminated groundwater. To meet the optimal performance, the direction of the electric field should be set opposite to the flow field. This work has successfully used a coupling model to predict uranium contaminant-plume evolution in CRS and estimate the performance of each component.
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Affiliation(s)
- Fuxin Zheng
- Engineering Research Center for Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China
| | - Yuanzheng Zhai
- Engineering Research Center for Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
| | - Weifeng Yue
- Engineering Research Center for Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China
| | - Yanguo Teng
- Engineering Research Center for Groundwater Pollution Control and Remediation of Ministry of Education of China, College of Water Sciences, Beijing Normal University, Beijing, 100875, China
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Zhang Y, Chen M, Wang J, Deng Y, Li Z. A new method for assessment of electro-osmotic permeability through the integration of theoretical and experimental ion flux in electrokinetic processes. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132049. [PMID: 37478588 DOI: 10.1016/j.jhazmat.2023.132049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/23/2023]
Abstract
Electrokinetic (EK) technology is promising for removing heavy metals from contaminated unsaturated soils. It is crucial to accurately determine the unsaturated electro-osmotic permeability for predicting the efficiency of EK treatment, optimizing treatment strategies, and accurately predicting the distribution of contaminant concentrations. However, the current approach of estimating unsaturated electro-osmotic permeability, which involves measuring effective voltage, drainage volume, and performing exponential fitting, fails to address the issue of uneven voltage gradient distribution during EK treatment. Herein, a novel method was presented for estimating the electro-osmotic permeability of unsaturated porous media. This method quantifies the electro-osmotic flow in an unsaturated porous medium by considering the difference in mass-transfer efficiency (MTE) between real (with electro-osmotic flow) and hypothetical cases (without electro-osmotic flow). This difference serves as a metric for estimating the electro-osmotic permeability. Results revealed a linear relationship between the electro-osmotic permeability and the product of volumetric moisture content and tortuosity, with the slope related to the ionic mobility of target ions, hypothetical and actual MTE. To validate this method, hexavalent Cr (Cr(VI)) was selected as the target contaminant and six EK experiments were conducted with varying initial volumetric moisture content. The feasibility of the method was evaluated by fitting the results of these experiments to obtain the specific slope of the porous medium used. Compared to the existing effective voltage-drainage volume-exponential fitting method, the proposed method offers several advantages. First, it effectively addressed the issue of nonuniform voltage distribution during EK treatment in the unsaturated porous medium. Second, it overcame the problem of a nonzero electro-osmotic permeability at zero volumetric moisture content in the exponential empirical formula. Third, the proposed method was based on theoretical derivations instead of relying solely on empirical fitting. Finally, the proposed method does not require a prior estimate of the saturated electro-osmotic permeability of the porous medium.
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Affiliation(s)
- Yuting Zhang
- Guangdong Key Laboratory of Contaminated Environmental Management and Remediation, Guangdong Provincial Academy of Environmental Science, Guangzhou 510045, China; School of Earth Science and Engineering, Hohai University, No.8 Focheng West Road, Nanjing 211100, China; Department of Civil & Mineral Engineering, University of Toronto, 35 St. George Street, Toronto, ON M5S 1A4, Canada
| | - Meng Chen
- Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
| | - Jinguo Wang
- School of Earth Science and Engineering, Hohai University, No.8 Focheng West Road, Nanjing 211100, China.
| | - Yirong Deng
- Guangdong Key Laboratory of Contaminated Environmental Management and Remediation, Guangdong Provincial Academy of Environmental Science, Guangzhou 510045, China.
| | - Zhaofeng Li
- State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology), Chengdu 610059, China; College of Environment and Civil Engineering, Chengdu University of Technology, Chengdu 610059, China
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López-Vizcaíno R, Cabrera V, Sprocati R, Muniruzzaman M, Rolle M, Navarro V, Yustres Á. A modeling approach for electrokinetic transport in double-porosity media. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Adsorption behaviour and mechanism of benzene, toluene and m-xylene (BTX) solution onto kaolinite: Experimental and molecular dynamics simulation studies. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120940] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Rolle M, Albrecht M, Sprocati R. Impact of solute charge and diffusion coefficient on electromigration and mixing in porous media. JOURNAL OF CONTAMINANT HYDROLOGY 2022; 244:103933. [PMID: 34872016 DOI: 10.1016/j.jconhyd.2021.103933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
The application of electrokinetic techniques in porous media has great potential to enhance mass transfer rates and, thus, to mobilize contaminants and effectively deliver reactants and amendments. However, the transport mechanisms induced by the application of an external electric field are complex and entail the coupling of physical, chemical and electrostatic processes. In this study we focus on electromigration and we provide experimental evidence of the impact of compound-specific properties, such as the aqueous diffusivity and the valence of charged species, on the macroscopic electrokinetic transport. We performed a series of multidimensional experiments considering the displacement of three different tracer plumes (i.e., permanganate, allura red and new coccine) in different background electrolyte solutions. The outcomes of the experiments clearly show that both the compound-specific diffusivity and the charge of the injected and resident ions impact the transport of the selected color tracer plumes, whose evolution was monitored with image analysis. The investigated experimental scenarios led to distinct plume behavior characterized by different mass distribution, average displacement velocities, longitudinal and lateral plume spreading, shape of the invading and receding fronts, as well as dilution of the injected solutes. A numerical simulator, based on the Nernst-Planck-Poisson equations and on aqueous speciation reactions in the pore water, allowed us to quantitatively interpret the experimental results, to capture the observed patterns of plume evolution, and to illuminate the coupling between the governing physico-chemical mechanisms and the controlling role of small scale compound-specific and electrostatic properties. Finally, the model was also extended to a typical configuration of in situ electrokinetic remediation of contaminated groundwater to show the impact of such mechanisms at larger scale.
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Affiliation(s)
- Massimo Rolle
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800, Kgs. Lyngby, Denmark.
| | - Marina Albrecht
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800, Kgs. Lyngby, Denmark
| | - Riccardo Sprocati
- Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800, Kgs. Lyngby, Denmark
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Evolution of Hydraulic Conductivity of Unsaturated Compacted Na-Bentonite under Confined Condition-Including the Microstructure Effects. MATERIALS 2021; 15:ma15010219. [PMID: 35009364 PMCID: PMC8745896 DOI: 10.3390/ma15010219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/20/2021] [Accepted: 12/24/2021] [Indexed: 11/30/2022]
Abstract
Compacted bentonite is envisaged as engineering buffer/backfill material in geological disposal for high-level radioactive waste. In particular, Na-bentonite is characterised by lower hydraulic conductivity and higher swelling competence and cation exchange capacity, compared with other clays. A solid understanding of the hydraulic behaviour of compacted bentonite remains challenging because of the microstructure expansion of the pore system over the confined wetting path. This work proposed a novel theoretical method of pore system evolution of compacted bentonite based on its stacked microstructure, including the dynamic transfer from micro to macro porosity. Furthermore, the Kozeny–Carman equation was revised to evaluate the saturated hydraulic conductivity of compacted bentonite, taking into account microstructure effects on key hydraulic parameters such as porosity, specific surface area and tortuosity. The results show that the prediction of the revised Kozeny–Carman model falls within the acceptable range of experimental saturated hydraulic conductivity. A new constitutive relationship of relative hydraulic conductivity was also developed by considering both the pore network evolution and suction. The proposed constitutive relationship well reveals that unsaturated hydraulic conductivity undergoes a decrease controlled by microstructure evolution before an increase dominated by dropping gradient of suction during the wetting path, leading to a U-shaped relationship. The predictive outcomes of the new constitutive relationship show an excellent match with laboratory observation of unsaturated hydraulic conductivity for GMZ and MX80 bentonite over the entire wetting path, while the traditional approach overestimates the hydraulic conductivity without consideration of the microstructure effect.
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Wang Y, Han Z, Li A, Cui C. Enhanced electrokinetic remediation of heavy metals contaminated soil by biodegradable complexing agents. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 283:117111. [PMID: 33857881 DOI: 10.1016/j.envpol.2021.117111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 03/02/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
In this study, an electrokinetic technique for remediation of Pb2+, Zn2+ and Cu2+ contaminated soil was explored using sodium alginate (SA) and chitosan (CTS) as promising biodegradable complexing agents. The highest Cu2+ (95.69%) and Zn2+ (95.05%) removal rates were obtained at a 2 wt% SA dosage, which demonstrated that SA significantly improved the Cu2+ and Zn2+ removal efficiency during electrokinetic process. The abundant functional groups of SA allowed metal ions desorption from soil via ion-exchange, complexation, and electrolysis. Pb2+ ions were difficult to remove from soil by SA due to the higher gelation affinity with Pb2+ than Cu2+ and Zn2+, despite the Pb2+ exchangeable fraction partially transforming to the reducible and oxidizable fractions. CTS could complex metal ions and migrate into the catholyte under the electric field to form crosslinked CTS gelations. Consequently, this study proved the suitability of biodegradable complexing agents for treating soil contaminated with heavy metals using electrokinetic remediation.
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Affiliation(s)
- Yuchen Wang
- School of Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China
| | - Zijian Han
- School of Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China
| | - Ang Li
- School of Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China
| | - Chongwei Cui
- School of Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, People's Republic of China.
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10
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Remediation of Multiply Contaminated Ground via Permeable Reactive Barrier and Electrokinetic Using Recyclable Food Scrap Ash (FSA). APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10041194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A study of the application of electrokinetic (EK) remediation and Permeable Reactive Barriers (PRB) using recyclable Foods Scrap Ash (FSA) in multiple contaminated soils was carried out. An FSA was chosen as a PRB fill material due to its highly efficient capacity for contaminant removal. Acetic acid and Brij30 were used as enhancers on copper and phenanthrene, respectively, to improve EK remediation performance in removing the heavy metal and organic contaminants. Copper adsorption in PRB was so substantial that the confirmed removal efficiency was 83.86–90.17% and the remaining amount was 105–212 mg. While a high removal efficiency of acetic acid was observed on copper in multiple contamination soils; the removal of phenanthrene was hardly detected and the recovery rate of the contaminant was low during pretreatment. Therefore; an additional study of pretreatment on the phenanthrene-contaminated kaolinite needs to be performed.
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11
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Sprocati R, Rolle M. Charge interactions, reaction kinetics and dimensionality effects on electrokinetic remediation: A model-based analysis. JOURNAL OF CONTAMINANT HYDROLOGY 2020; 229:103567. [PMID: 31780056 DOI: 10.1016/j.jconhyd.2019.103567] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/09/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
The potential of electrokinetic remediation technologies (EKR) for the removal of different contaminants from subsurface porous media has been increasingly recognized. Despite electrokinetic applications have shown promising results, quantitative understanding of such systems is still challenging due to the complex interplay between physical transport processes, electrostatic interactions, and geochemical reactions. In this study, we perform a model-based analysis of electrokinetic transport in saturated porous media. We investigate the effects of: (i) Coulombic interactions between ions in the system mobilized by electromigration, (ii) reaction kinetics on the overall removal efficiency of a non-charged organic contaminant, and (iii) dimensionality and different electrode configurations. The results show that such effects play a major role on the performance of electrokinetic systems. The simulations illuminate the importance of microscopic processes, such as electrostatic interactions and ion-specific diffusivities, and their non-intuitive macroscopic impact on the delivery of charged amendments and on the efficiency of contaminant removal. The insights of this study are valuable to improve and optimize the design and the operational strategies of electrokinetic remediation systems.
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Affiliation(s)
- Riccardo Sprocati
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Massimo Rolle
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs. Lyngby, Denmark.
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Shu J, Sun X, Liu R, Liu Z, Wu H, Chen M, Li B. Enhanced electrokinetic remediation of manganese and ammonia nitrogen from electrolytic manganese residue using pulsed electric field in different enhancement agents. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 171:523-529. [PMID: 30641313 DOI: 10.1016/j.ecoenv.2019.01.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/16/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Electrolytic manganese residue (EMR) is a solid waste generated in the process of producing electrolytic metal manganese and contains a lot of manganese and ammonia nitrogen. In this study, electrokinetic remediation (EK) of manganese and ammonia nitrogen from EMR were carried out by using pulse electric field (PE) in different agents, and sodium dodecyl benzene sulfonate (SDBS), citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) were used as enhancement agents. The removal behavior of ammonia nitrogen and manganese under direct current field (DC) and PE, and the relationship between manganese fractionation and transport behavior, as well as the energy consumption were investigated. The results demonstrated that the removal efficiency of ammonia nitrogen and manganese using PE were higher than DC. SDBS, EDTA and CA could enhance electroosmosis and electromigration, and the sequence of enhancement agent effects were CA, SDBS, EDTA, distilled water. The highest removal efficiency of manganese and ammonia nitrogen were 94.74% and 88.20%, and the effective removal amount of manganese and ammonia nitrogen was 23.93 and 1.48 mg·wh-1, when CA and SDBS+CA was used as the enhancement agents, respectively. Moreover, electromigration was the main removal mechanism of manganese and ammonia nitrogen in the EK process.
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Affiliation(s)
- Jiancheng Shu
- Key Laboratory of Solid Waste Treatment and Resource Recycle (SWUST), Ministry of Education, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang 621010, China.
| | - Xiaolong Sun
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Renlong Liu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Zuohua Liu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
| | - Haiping Wu
- Sichuan jiuzhou technician college, 9 Ninesheng Road, Mianyang 621099, China
| | - Mengjun Chen
- Key Laboratory of Solid Waste Treatment and Resource Recycle (SWUST), Ministry of Education, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang 621010, China
| | - Bobo Li
- College of Mining, Guizhou University, Guiyang 550025, PR China
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López-Vizcaíno R, dos Santos E, Yustres A, Rodrigo M, Navarro V, Martínez-Huitle C. Calcite buffer effects in electrokinetic remediation of clopyralid-polluted soils. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2018.11.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Korolev VA, Nesterov DS. Influence of electro-osmosis on physicochemical parameters and microstructure of clay soils. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2019; 54:560-571. [PMID: 30729856 DOI: 10.1080/10934529.2019.1571321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 01/04/2019] [Accepted: 01/08/2019] [Indexed: 06/09/2023]
Abstract
The change in properties and structure of clay soils due to electro-osmosis was studied. These alterations were exemplified by mantle loam and kaolin. It is shown that electro-osmotic treatment of the soils on the open scheme resulted in the transformations in their moisture content, total and dry density, salinity, pH, and the parameters of their particles. The most notable changes occurred within the diffuse double layers (DDLs) of soil particles such as their recharge in the anodic zone. The transformations of the loam particles DDLs resulted in their aggregation in the cathodic and anodic zones. Also, electro-osmotic flow caused the redistribution of pore sizes within the soils between the electrodes. In the case of the kaolin, electro-osmosis resulted in the formation of the anisotropic, flow-oriented structure. The change in the types of soil particles contacts formed was observed during electro-osmosis as well. The obtained data can be used to study the behavior of soil during electro-osmosis as a function of the soil type.
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Affiliation(s)
- V A Korolev
- a Faculty of Geology, Department of Engineering and Ecological Geology , Lomonosov Moscow State University , Moscow , Russia
| | - D S Nesterov
- a Faculty of Geology, Department of Engineering and Ecological Geology , Lomonosov Moscow State University , Moscow , Russia
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López Vizcaíno R, Yustres A, Asensio L, Saez C, Cañizares P, Rodrigo MA, Navarro V. Enhanced electrokinetic remediation of polluted soils by anolyte pH conditioning. CHEMOSPHERE 2018; 199:477-485. [PMID: 29454170 DOI: 10.1016/j.chemosphere.2018.02.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 05/09/2023]
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.
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Affiliation(s)
- R López Vizcaíno
- University of Castilla-La Mancha, Institute of Technology, Campus Universitario s/n, 16071 Cuenca, Spain.
| | - A Yustres
- University of Castilla-La Mancha, Institute of Technology, Campus Universitario s/n, 16071 Cuenca, Spain
| | - L Asensio
- University of Castilla-La Mancha, Institute of Technology, Campus Universitario s/n, 16071 Cuenca, Spain
| | - C Saez
- Department of Chemical Engineering, Faculty of Chemical Sciences & Technologies, University of Castilla-La Mancha, Campus Universitario s/n, 13071 Ciudad Real, Spain
| | - P Cañizares
- Department of Chemical Engineering, Faculty of Chemical Sciences & Technologies, University of Castilla-La Mancha, Campus Universitario s/n, 13071 Ciudad Real, Spain
| | - M A Rodrigo
- Department of Chemical Engineering, Faculty of Chemical Sciences & Technologies, University of Castilla-La Mancha, Campus Universitario s/n, 13071 Ciudad Real, Spain
| | - V Navarro
- University of Castilla-La Mancha, Institute of Technology, Campus Universitario s/n, 16071 Cuenca, Spain
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