Relevance of gaseous flows in electrochemically assisted soil thermal remediation

Henrique, João Miller de Melo; Cañizares, Pablo; Sáez, Cristina; Santos, Elisama Vieira dos; Rodrigo, Manuel A.

doi:10.1016/j.coelec.2021.100698

Cited by 5 publications

(5 citation statements)

References 55 publications

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“…However, it can be seen that the mobility in the transverse directions (y and z axis) was almost negligible as compared with the longitudinal mobility in the x axis (consider the log scale), what means that the systems can be considered as a 1‐D to do further evaluations based on a maximum‐gradient modelling approach. [8b] …”

Section: Resultsmentioning

confidence: 99%

“…The initial concentration of the source zone was 848 mg kg −1 and, as observed, it distributes in a different way in the three mockups studied in this work (Figure 3). However, it can be seen that the mobility in the transverse directions (y and z axis) was almost negligible as compared with the longitudinal mobility in the x axis (consider the log scale), what means that the systems can be considered as a 1‐D to do further evaluations based on a maximum‐gradient modelling approach [8b] …”

Section: Resultsmentioning

confidence: 99%

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Combining Soil Vapor Extraction and Electrokinetics for the Removal of Hexachlorocyclohexanes from Soil

et al. 2022

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This paper focuses on the evaluation of the mobility of four hexachlorocyclohexane (HCH) isomers by soil vapor extraction (SVE) coupled with direct electrokinetic (EK) treatment without adding flushing fluids. SVE was found to be very efficient and remove nearly 70 % of the four HCH in the 15‐days of the tests. The application of electrokinetics produced the transport of HCH to the cathode by different electrochemical processes, which were satisfactorily modelled with a 1‐D transport equation. The increase in the electric field led to an increase in the transport of pollutants, although 15 days was found to be a very short time for an efficient transportation of the pollutants to the nearness of the cathode. Loss of water content in the vicinity of the cathode warns about the necessity of using electrokinetic flushing technologies instead of simple direct electrokinetics. Thus, results point out that direct electrokinetic treatment without adding flushing fluids produced low current intensities and ohmic heating that contributes negatively to the performance of the SVE process. No relevant differences were found among the removal of the four isomers, neither in SVE nor in EK processes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Combining Soil Vapor Extraction and Electrokinetics for the Removal of Hexachlorocyclohexanes from Soil

et al. 2022

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“…Applying this current intensity was possible to access the production of H 2 , an energy carrier, with 74% H 2 purity. Electrokinetics have been coupled with electrodialytic technology for H 2 production during the removal of pollutants [20], where the energy requirements for this system are considerably smaller owing to the higher conductivity of the matrix [46]. Additionally, regarding the As removal, a better performance was achieved (48%) in comparison with scenario 1 (16%).…”

Section: Ed Treatment With H 2 Recoverymentioning

confidence: 99%

Life Cycle Assessment of Electrodialytic Technologies to Recover Raw Materials from Mine Tailings

et al. 2021

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Currently, the development of new sustainable technologies to recover raw materials from secondary resources has shown a lack of available data on the processes and supplies involved, as well as their environmental impacts. The present research has conducted a life cycle assessment of electrodialytic (ED) technologies to improve critical raw materials recovery in the Portuguese mining industry. To critically appraise the activities from the mining sector and gather data on technical and environmental issues, three waste management scenarios were considered: (1) ED treatment with a deep eutectic solvent as an adjuvant; (2) ED treatment with simultaneous H2 recovery; and (3) ED treatment with sodium chloride as an enhancement. The data presented were based on global databases, technical reports from official sources, and peer-reviewed published experimental outcomes. The estimated results indicated that one of the constraints in applying ED technologies is energy consumption and thus the impacts are highly dependent on energy source choices. On the other hand, as a consequence of the H2 inherently produced by ED technologies, there is a direct potential for energy recovery. Therefore, considering an upscale approach of the ED reactor based on bench scale experimental results, the H2 could be reused in the ED facility or stored. Additionally, according to experimental data, 22% of the tungsten from the fine mine tailings could be recovered. Finally, the possibility to remove 63% of arsenic from mine tailings could decrease contamination risks while creating additional marketable co-products.

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“…Electromigration (transport of ions and ionic complexes to opposite electrodes), electro-osmosis (movement of groundwater to cathode due to surface charge phenomena), electrophoresis (transport of charged particles to opposite electrodes) and electrolysis (oxidation and reduction of water in anodic and cathodic regions, resulting in hydrogen and hydroxide species, creating acidic and alkaline gradients) are the most important transport phenomena. 4,[12][13][14] Moreover, electrodeposition, sorption, desorption, precipitation and dissolution mechanisms can be also promoted.…”

Section: Introductionmentioning

confidence: 99%

“…During the EK process, the application of an electric field among electrodes placed in the soil promotes the mobilization of pollutants through several mechanisms, favoring the elimination of heavy metals and/or organic compounds, in situ , when combined with other technologies. Electromigration (transport of ions and ionic complexes to opposite electrodes), electro‐osmosis (movement of groundwater to cathode due to surface charge phenomena), electrophoresis (transport of charged particles to opposite electrodes) and electrolysis (oxidation and reduction of water in anodic and cathodic regions, resulting in hydrogen and hydroxide species, creating acidic and alkaline gradients) are the most important transport phenomena 4,12‐14 . Moreover, electrodeposition, sorption, desorption, precipitation and dissolution mechanisms can be also promoted.…”

Section: Introductionmentioning

confidence: 99%

Cork‐based permeable reactive barriers coupled to electrokinetic processes for interrupting pollutants reaching groundwater: a case study of lead‐contaminated soil

Silva

Henrique

Vilar

et al. 2022

J of Chemical Tech & Biotech

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BACKGROUND A novel, original and green technology for the remediation of lead‐contaminated soil is proposed. The treatment strategy integrates two well‐known technologies: electrokinetic (EK) remediation and permeable reactive barriers (PRBs). The novelty of the present work is based on the use of cork granules, as reactive media, in the PRBs for interrupting Pb reaching groundwater. The cork barrier (treatment zone) was emplaced near the anodic compartment to favor the retention and sorption of Pb due to the migration/diffusion effects promoted from soil to the anode during EK remediation. For this purpose, NaNO3 (0.1 mol L−1) and citric acid (0.1 mol L−1) were tested as supporting electrolytes in the cathodic reservoir, while in the anodic compartment a solution of 0.1 mol L−1 NaNO3 was used. Additionally, the influence of direct current and reverse polarity approaches on EK efficiency was evaluated. RESULTS Results clearly indicated that the novel cork‐based PRBs concept was efficient when coupled with EK. Nevertheless, pH conditions played a significant role in Pb sorption by cork granules as well as in the physical–chemical properties of cork under an electrical field. The transportation of Pb by EK, towards the PRB with cork granules, was favored through the use of citric acid in the catholyte and reverse polarity strategy. CONCLUSIONS These approaches promote a better pH control in the soil and electrode wells, being able to reach near 80% Pb removal from soil, after 14 days of experiment. Therefore, this technology can be used for in situ remediation of Pb‐contaminated groundwater. © 2022 Society of Chemical Industry (SCI).

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Relevance of gaseous flows in electrochemically assisted soil thermal remediation

Cited by 5 publications

References 55 publications

Combining Soil Vapor Extraction and Electrokinetics for the Removal of Hexachlorocyclohexanes from Soil

Combining Soil Vapor Extraction and Electrokinetics for the Removal of Hexachlorocyclohexanes from Soil

Life Cycle Assessment of Electrodialytic Technologies to Recover Raw Materials from Mine Tailings

Cork‐based permeable reactive barriers coupled to electrokinetic processes for interrupting pollutants reaching groundwater: a case study of lead‐contaminated soil

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