8 results on '"Local chemical equilibrium"'
Search Results
2. Modeling of electrokinetic remediation combining local chemical equilibrium and chemical reaction kinetics.
- Author
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Masi, Matteo, Paz-Garcia, Juan Manuel, Gomez-Lahoz, Cesar, Villen-Guzman, Maria, Ceccarini, Alessio, and Iannelli, Renato
- Subjects
- *
CHEMICAL equilibrium , *CHEMICAL kinetics , *EQUILIBRIUM reactions , *CHEMICAL reactions , *WATER electrolysis , *CALCAREOUS soils - Abstract
• Reaction kinetics plays a major role in electrokinetic remediation rate. • Release of contaminants has time-dependent behavior in calcareous soils. • We combined kinetic and equilibrium laws for the description of chemical reactions. • Model predictions significantly improve when kinetic rates are taken into account. 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. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
3. Thermodynamics of rapid solidification and crystal growth kinetics in glass-forming alloys
- Author
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Galenko, P. K., Ankudinov, V., Reuther, K., Rettenmayr, M., Salhoumi, A., Kharanzhevskiy, E. V., Galenko, P. K., Ankudinov, V., Reuther, K., Rettenmayr, M., Salhoumi, A., and Kharanzhevskiy, E. V.
- Abstract
Thermodynamic driving forces and growth rates in rapid solidification are analysed. Taking into account the relaxation time of the solute diffusion flux in the model equations, the present theory uses, in a first case, the deviation from local chemical equilibrium, and ergodicity breaking. The second case of ergodicity breaking may exist in crystal growth kinetics of rapidly solidifying glass-forming metals and alloys. In this case, a theoretical analysis of dendritic solidification is given for congruently melting alloys in which chemical segregation does not occur. Within this theory, a deviation from thermodynamic equilibrium is introduced for high undercoolings via gradient flow relaxation of the phase field. A comparison of the present derivations with previously verified theoretical predictions and experimental data is given. This article is part of the theme issue 'Heterogeneous materials: Metastable and nonergodic internal structures'. ©2019 The Author(s) Published by the Royal Society.
- Published
- 2019
4. Thermodynamics of rapid solidification and crystal growth kinetics in glass-forming alloys
- Author
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Klemens Reuther, Vladimir Ankudinov, E. V. Kharanzhevskiy, Peter Galenko, Markus Rettenmayr, and A. Salhoumi
- Subjects
LOCAL CHEMICAL EQUILIBRIUM ,Materials science ,Field (physics) ,Thermodynamic equilibrium ,THERMODYNAMIC DRIVING FORCES ,General Mathematics ,THERMODYNAMIC EQUILIBRIA ,General Physics and Astronomy ,Thermodynamics ,GLASS ,Crystal growth ,GLASS-FORMING ALLOYS ,Phase (matter) ,Metastability ,FAST TRANSFORMATIONS ,THERMODYNAMICS ,GROWTH KINETICS ,DENDRITIC SOLIDIFICATION ,RAPID SOLIDIFICATION ,CHEMICAL ANALYSIS ,Ergodicity ,Relaxation (NMR) ,General Engineering ,GROWTH OF CRYSTALS ,Articles ,CHEMICAL SEGREGATION ,FAST TRANSFORMATION ,GLASS TRANSITION ,CRYSTAL GROWTH ,HETEROGENEOUS MATERIALS ,Chemical equilibrium ,METALLURGY - Abstract
Thermodynamic driving forces and growth rates in rapid solidification are analysed. Taking into account the relaxation time of the solute diffusion flux in the model equations, the present theory uses, in a first case, the deviation from local chemical equilibrium, and ergodicity breaking. The second case of ergodicity breaking may exist in crystal growth kinetics of rapidly solidifying glass-forming metals and alloys. In this case, a theoretical analysis of dendritic solidification is given for congruently melting alloys in which chemical segregation does not occur. Within this theory, a deviation from thermodynamic equilibrium is introduced for high undercoolings via gradient flow relaxation of the phase field. A comparison of the present derivations with previously verified theoretical predictions and experimental data is given. This article is part of the theme issue 'Heterogeneous materials: Metastable and nonergodic internal structures'. ©2019 The Author(s) Published by the Royal Society.
- Published
- 2019
5. Modeling of electrokinetic remediation combining local chemical equilibrium and chemical reaction kinetics
- Author
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Renato Iannelli, Cesar Gomez-Lahoz, Matteo Masi, Maria Villen-Guzman, Juan Manuel Paz-Garcia, and Alessio Ceccarini
- Subjects
local chemical equilibrium ,Environmental Engineering ,Materials science ,Health, Toxicology and Mutagenesis ,Diffusion ,electrokinetic remediation ,Kinetics ,0211 other engineering and technologies ,Electrokinetic remediation ,Thermodynamics ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Chemical reaction ,Electrokinetic phenomena ,Environmental Chemistry ,Cinética química ,Waste Management and Disposal ,Dissolution ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,Aqueous solution ,Reactive-transport model ,calcite dissolution kinetics ,Calcite dissolution kinetics ,Pollution ,13. Climate action ,Chemical equilibrium ,Local chemical equilibrium - 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 mechanism 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. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Part of this work was supported financially by the European Commission within the project LIFE12 ENV/IT/442 SEKRET “Sediment electrokinetic remediation technology for heavy metal pollution removal”. Paz-Garcia acknowledges the financial support from the “Proyecto Puente - Plan Propio de Investigación y Transferencia de la Universidad de Málaga”, code: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the financial support from the University of Malaga through a postdoctoral contract.
- Published
- 2017
6. Influence of chemical reaction kinetics on electrokinetic remediation modelling results
- Author
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Masi, Matteo, Paz-Garcia, Juan Manuel, Gomez-Lahoz, Cesar, Villen-Guzman, Maria, Ceccarini, Alessio, and Iannelli, Renato
- Subjects
Reactive-transport model ,Electrokinetic remediation ,Calcite dissolution kineticsodel ,Electrocinética ,Local chemical equilibrium - Abstract
A numerical model describing transport of multiple species and chemical reactions during electrokinetic treatment is presented. The transport mechanisms included in the model were electromigration and electroosmosis. The chemical reactions taken into account were water electrolysis at the electrodes, aqueous species complexation, precipitation, and dissolution. The model was applied to simulate experimental data from an acid-enhanced electrokinetic treatment of a Pb-contaminated calcareous soil. The kinetics of the main pH buffering process (i.e., calcite dissolution) was taken into account and its time-dependent behavior was described by a rate law. The influence of kinetics was evaluated by comparing the results from a set of simulations in which calcite dissolution was implemented considering thermodynamic equilibrium and another set in which the same reaction was described by the rate law. The results show that the prediction capability of the model significantly improves when the kinetic rate is taken into account. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
- Published
- 2017
7. Zone Evolution in Isoelectric Focusing
- Author
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Babskii, V. G., Zhukov, M. Yu., Yudovich, V. I., Babskii, V. G., Zhukov, M. Yu., and Yudovich, V. I.
- Published
- 1989
- Full Text
- View/download PDF
8. Chemical Subsystems
- Author
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Babskii, V. G., Zhukov, M. Yu., Yudovich, V. I., Babskii, V. G., Zhukov, M. Yu., and Yudovich, V. I.
- Published
- 1989
- Full Text
- View/download PDF
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