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Xie N, Wang H, You C. On the electrokinetic remediation of Pb-contaminated soil: A coupled electro-transport-reaction modelling study based on chemical reaction kinetics. Chemosphere 2024; 355:141661. [PMID: 38521103 DOI: 10.1016/j.chemosphere.2024.141661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/14/2024] [Accepted: 03/05/2024] [Indexed: 03/25/2024]
Abstract
The accumulation of lead (Pb) in soil resulted from industrialization and urbanization poses a threat to human health and the ecosystem. This study proposes a mathematical model for Pb migration and transformation in soil porous media, aiming to guide the design of electrokinetic remediation schemes for Pb-contaminated soils. To improve the validity of the model, the chemical reactions considered in the model are all based on chemical reaction kinetics, which were usually overlooked for model simplification. The model quantitatively describes various physical and chemical processes of Pb at the soil-pore fluid interface and in the pore fluid, including diffusion, electromigration, electroosmosis, electrolytic water reaction, precipitation, adsorption/desorption, protonation/deprotonation reaction, and water self-ionization reaction. The numerical results show that the pH value is a key factor affecting the distribution of Pb in the soil and determining the removal efficiency of Pb. The effects of different enhancement methods on Pb concentration distribution and removal efficiency were evaluated with this model. It was found that placing a cation exchange membrane at the cathode boundary while using 0.01 M nitric acid as anode electrolyte can effectively improve Pb removal efficiency from 3.9% to 93.6%. The developed model can be used to guide the design of the enhanced electrokinetic remediation schemes.
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Affiliation(s)
- Ning Xie
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, PR China; Shanxi Research Institute for Clean Energy, Tsinghua University, Taiyuan, PR China
| | - Haiming Wang
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, PR China; Shanxi Research Institute for Clean Energy, Tsinghua University, Taiyuan, PR China.
| | - Changfu You
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, PR China; Shanxi Research Institute for Clean Energy, Tsinghua University, Taiyuan, PR China
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Sorwat J, Mellage A, Maisch M, Kappler A, Cirpka OA, Byrne JM. Chromium (VI) removal kinetics by magnetite-coated sand: Small-scale flow-through column experiments. J Hazard Mater 2021; 415:125648. [PMID: 34088175 DOI: 10.1016/j.jhazmat.2021.125648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/25/2021] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
Magnetite nanoparticles are promising materials for treating toxic Cr(VI), but safe handling is challenging due to their small size. We prepared flow-through columns containing 10% or 100% (v/v) magnetite-coated sand. Cr(VI) removal efficiency was determined for different Cr(VI) concentrations (0.1 or 1.0 mM), neutral or alkaline pH, and oxic/anoxic conditions. We formulated a reactive-transport model that accurately predicted total Cr removal, accounting for reversible and irreversible (chemi)sorption reactions. Our results show that the material removes and irreversibly sequesters Cr(VI). For the concentration range used 10% and 100% (v/v) -packed columns removed > 99% and 72% of influent Cr(VI), respectively. Two distinct parameter sets were necessary to fit the identical model formulation to the 10 or 100% (v/v) columns (e.g., maximum sorption capacities (qmax) of 1.37 µmol Cr/g sand and 2.48 µmol Cr/g, respectively), which we attributed to abrasion-driven magnetite micro-particle detachment during packing yielding an increase in reactive surface area. Furthermore, experiments under oxic conditions showed that, even when handled in the presence of O2, the magnetite-coated sand maintained a high removal capacity (47%). Our coupled experimental and modelling analyses indicates that magnetite-coated sand is a promising and suitable medium for treating Cr(VI)-contaminated water in fixed-bed reactors or permeable reactive barriers.
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Affiliation(s)
- Julian Sorwat
- Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Schnarrenbergstr 94-96, 72076 Tübingen, Germany
| | - Adrian Mellage
- Hydrogeology, Center for Applied Geoscience, University of Tübingen, Schnarrenbergstr 94-96, 72076 Tübingen, Germany
| | - Markus Maisch
- Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Schnarrenbergstr 94-96, 72076 Tübingen, Germany
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geoscience, University of Tübingen, Schnarrenbergstr 94-96, 72076 Tübingen, Germany
| | - Olaf A Cirpka
- Hydrogeology, Center for Applied Geoscience, University of Tübingen, Schnarrenbergstr 94-96, 72076 Tübingen, Germany
| | - James M Byrne
- School of Earth Sciences, Wills Memorial Building, University of Bristol, Bristol BS8 1RJ, United Kingdom.
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Meng S, Li X, Siitari-Kauppi M, Liu L. Development and application of an advection-dispersion model for data analysis of electromigration experiments with intact rock cores. J Contam Hydrol 2020; 231:103618. [PMID: 32147205 DOI: 10.1016/j.jconhyd.2020.103618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 01/08/2020] [Accepted: 01/23/2020] [Indexed: 06/10/2023]
Abstract
An advection-dispersion model was developed for interpreting the experimental results of electromigration in granitic rock cores. The most important mechanisms governing the movement of the tracer ions, i.e. electromigration, electroosmosis and dispersion were taken into account by the advection-dispersion model, but the influence of aqueous chemistry was ignored. An analytical solution in the Laplace domain was derived and then applied to analyze the measured results of a series of experiments, performed in an updated experimental device using different applied voltages. The modelling results suggested that both studied tracers, i.e. iodide and selenite, are effectively non-sorbing in the intact rock investigated. The effective diffusivities and formation factors evaluated from the model were also found to be in good agreement with data reported in literature and the associated uncertainties are much smaller than those obtained from the classical ideal plug-flow model, which accounts only for the dominant effect of electromigration on ionic transport. To explore further how the quality of parameter identifications would be influenced by neglect of aqueous chemistry, a reactive transport model was also implemented, which may be regarded as a multi-component version of the advection-dispersion model. The analysis showed that the advection-dispersion model works equally well as the reactive transport model but requires much less computational demand. It can, therefore, be used with great confidence to interpret the experimental results of electromigration for studies of diffusion and sorption behavior of radionuclides in intact rock cores.
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Affiliation(s)
- Shuo Meng
- Department of Chemical Engineering, KTH Royal Institute of Technology, S-100 44 Stockholm, Sweden.
| | - Xiaodong Li
- Department of Chemistry - Radiochemistry, University of Helsinki, P.O. Box 55, FI-000 14 Helsinki, Finland
| | - Marja Siitari-Kauppi
- Department of Chemistry - Radiochemistry, University of Helsinki, P.O. Box 55, FI-000 14 Helsinki, Finland
| | - Longcheng Liu
- Department of Chemical Engineering, KTH Royal Institute of Technology, S-100 44 Stockholm, Sweden
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Masi M, Paz-Garcia JM, Gomez-Lahoz C, Villen-Guzman M, Ceccarini A, Iannelli R. Modeling of electrokinetic remediation combining local chemical equilibrium and chemical reaction kinetics. J Hazard Mater 2019; 371:728-733. [PMID: 30925399 DOI: 10.1016/j.jhazmat.2019.03.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 02/05/2019] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
A mathematical model for reactive-transport processes in porous media is presented. The modeled system includes diffusion, electromigration and electroosmosis as the most relevant transport mechanisms and water electrolysis at the electrodes, aqueous species complexation, precipitation and dissolution as the chemical reactions taken place during the treatment time. The model is based on the local chemical equilibrium for most of the reversible chemical reactions occurring in the process. As a novel enhancement of previous models, the local chemical equilibrium reactive-transport model is combined with the solution of the transient equations for the kinetics of those chemical reactions that have representative rates in the same order than the transport mechanisms. The model is validated by comparison of simulation and experimental results for an acid-enhanced electrokinetic treatment of a real Pb-contaminated calcareous soil. The kinetics of the main pH buffering process, the calcite dissolution, was defined by a simplified empirical kinetic law. Results show that the evaluation of kinetic rate entails a significant improvement of the model prediction capability.
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Affiliation(s)
- Matteo Masi
- Department of Energy, Systems, Land and Construction Engineering, Univ. of Pisa, Pisa, Italy
| | - Juan Manuel Paz-Garcia
- Department of Chemical Engineering, Faculty of Sciences, Univ. of Malaga, Malaga, Spain.
| | - Cesar Gomez-Lahoz
- Department of Chemical Engineering, Faculty of Sciences, Univ. of Malaga, Malaga, Spain
| | - Maria Villen-Guzman
- Department of Chemical Engineering, Faculty of Sciences, Univ. of Malaga, Malaga, Spain
| | - Alessio Ceccarini
- Department of Chemistry and Industrial Chemistry, Univ. of Pisa, Pisa, Italy
| | - Renato Iannelli
- Department of Energy, Systems, Land and Construction Engineering, Univ. of Pisa, Pisa, Italy
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Paz-Garcia JM, Dykstra JE, Biesheuvel PM, Hamelers HVM. Energy from CO2 using capacitive electrodes - a model for energy extraction cycles. J Colloid Interface Sci 2014; 442:103-9. [PMID: 25525977 DOI: 10.1016/j.jcis.2014.11.045] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 11/17/2014] [Indexed: 12/01/2022]
Abstract
A model is presented for the process of harvesting electrical energy from CO2 emissions using capacitive cells. The principle consists of controlling the mixing process of a concentrated CO2 gas stream with a dilute CO2 gas stream (as, for example, exhaust gas and air), thereby converting part of the released mixing energy into electrical energy. The model describes the transient reactive transport of CO2 gas absorbed in water or in monoethanolamine (MEA) solutions, under the assumption of local chemical equilibrium. The model combines the selective transport of ions through ion-exchange membranes, the accumulation of charge in the porous carbon electrodes and the coupling between the ionic current and the produced electrical current and power. We demonstrate that the model can be used to calculate the energy that can be extracted by mixing concentrated and dilute CO2 containing gas streams. Our calculation results for the process using MEA solutions have various counterintuitive features, including: 1. When dynamic equilibrium is reached in the cyclical process, the electrical charge in the anode is negative both during charging and discharging; 2. Placing an anion-exchange membrane (AEM) in the system is not required, the energy per cycle is just as large with or without an AEM.
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Affiliation(s)
- J M Paz-Garcia
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911 MA Leeuwarden, The Netherlands
| | - J E Dykstra
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911 MA Leeuwarden, The Netherlands; Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - P M Biesheuvel
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911 MA Leeuwarden, The Netherlands; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | - H V M Hamelers
- Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 7, 8911 MA Leeuwarden, The Netherlands.
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