{"title":"Enhancing electrokinetic remediation of soil contaminated with As, Cd, Cu, and Pb using the biodegradable chelator GLDA: A pilot study","authors":"Zhiwei Pan, Genmei Wang, Jiaqi Liang, Long Cang","doi":"10.1007/s11368-024-03824-8","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Purpose</h3><p>This study aims to assess the feasibility and efficiency of electrokinetic (EK) remediation of soil contaminated with As, Cd, Cu, and Pb using the biodegradable chelator N, N-bis(carboxymethyl)-tetrasodium salt (GLDA) at the pilot scale.</p><h3 data-test=\"abstract-sub-heading\">Materials and methods</h3><p>The experiments were performed under a constant voltage (40 V) in an EK reactor (100 cm (length) × 50 cm (width) × 25 cm (height)) for over 100 days using various enhancement strategies. The current, electroosmotic flow (EOF), microstructure, mineral composition of the soil samples (before and after EK remediation), removal efficiencies, chemical forms, and ecotoxicity risks of As, Cd, Cu, and Pb were determined.</p><h3 data-test=\"abstract-sub-heading\">Results and discussion</h3><p>The results showed gradual decreases in the electrical current and EOF over time. The spatial distribution of As, Cd, Cu, and Pb in the soil solution and electrolyte revealed that the removed metals primarily accumulated in anolytes. The soil As, Cd, and Cu contents, especially near the anode, showed gradual reductions. The total removal efficiencies of As, Cd, Cu, and Pb were 49.4%, 44.0%, 53.6%, and 36.6%, respectively. Overall, the ecotoxicity risks of the remaining As, Cd, Cu, and Pb were below the initial values. A soil microstructure and mineral composition analysis indicated that the GLDA-enhanced EK technology effectively removed As, Cd, Cu, and Pb by dissolving soil minerals and breaking chemical bonds. The unit energy consumption ranged from 1.25 to 1.83 kW·h/t/%, indicating lower or comparable values to the data in the literature.</p><h3 data-test=\"abstract-sub-heading\">Conclusions</h3><p>The biodegradable chelator, GLDA, has been shown to remove different types of potentially toxic elements using enhancement strategies on a pilot scale with low unit energy consumption. Arsenic migrated to the anode in the anionic form, and the complexes formed by Cd, Cu, and Pb with GLDA were negatively charged and moved toward the cathode. After the EK treatment, the ecotoxicity risks of As, Cd, Cu, and Pb decreased with a reduction in the contents and the chemical form changes of As, Cd, Cu, and Pb.</p>","PeriodicalId":17139,"journal":{"name":"Journal of Soils and Sediments","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Soils and Sediments","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1007/s11368-024-03824-8","RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Purpose
This study aims to assess the feasibility and efficiency of electrokinetic (EK) remediation of soil contaminated with As, Cd, Cu, and Pb using the biodegradable chelator N, N-bis(carboxymethyl)-tetrasodium salt (GLDA) at the pilot scale.
Materials and methods
The experiments were performed under a constant voltage (40 V) in an EK reactor (100 cm (length) × 50 cm (width) × 25 cm (height)) for over 100 days using various enhancement strategies. The current, electroosmotic flow (EOF), microstructure, mineral composition of the soil samples (before and after EK remediation), removal efficiencies, chemical forms, and ecotoxicity risks of As, Cd, Cu, and Pb were determined.
Results and discussion
The results showed gradual decreases in the electrical current and EOF over time. The spatial distribution of As, Cd, Cu, and Pb in the soil solution and electrolyte revealed that the removed metals primarily accumulated in anolytes. The soil As, Cd, and Cu contents, especially near the anode, showed gradual reductions. The total removal efficiencies of As, Cd, Cu, and Pb were 49.4%, 44.0%, 53.6%, and 36.6%, respectively. Overall, the ecotoxicity risks of the remaining As, Cd, Cu, and Pb were below the initial values. A soil microstructure and mineral composition analysis indicated that the GLDA-enhanced EK technology effectively removed As, Cd, Cu, and Pb by dissolving soil minerals and breaking chemical bonds. The unit energy consumption ranged from 1.25 to 1.83 kW·h/t/%, indicating lower or comparable values to the data in the literature.
Conclusions
The biodegradable chelator, GLDA, has been shown to remove different types of potentially toxic elements using enhancement strategies on a pilot scale with low unit energy consumption. Arsenic migrated to the anode in the anionic form, and the complexes formed by Cd, Cu, and Pb with GLDA were negatively charged and moved toward the cathode. After the EK treatment, the ecotoxicity risks of As, Cd, Cu, and Pb decreased with a reduction in the contents and the chemical form changes of As, Cd, Cu, and Pb.
期刊介绍:
The Journal of Soils and Sediments (JSS) is devoted to soils and sediments; it deals with contaminated, intact and disturbed soils and sediments. JSS explores both the common aspects and the differences between these two environmental compartments. Inter-linkages at the catchment scale and with the Earth’s system (inter-compartment) are an important topic in JSS. The range of research coverage includes the effects of disturbances and contamination; research, strategies and technologies for prediction, prevention, and protection; identification and characterization; treatment, remediation and reuse; risk assessment and management; creation and implementation of quality standards; international regulation and legislation.