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  • Final Report Summary - NOVEED (A novel energy efficient electrodialysis cell to recycle Acids and Bases from industrial process water based on new types of electrodes to enable internal energy recovery)
FP7

NOVEED Streszczenie raportu

Project ID: 606304
Źródło dofinansowania: FP7-SME
Kraj: Germany

Final Report Summary - NOVEED (A novel energy efficient electrodialysis cell to recycle Acids and Bases from industrial process water based on new types of electrodes to enable internal energy recovery)

Executive Summary:
Electrodialysis (ED) is an electrochemical membrane process technology which is used especially for desalination of sea or brackish water, e.g. for drinking water supply. In this case, the salt ions of the inlet stream (seawater or brackish water) are separated by an applied electric field and using cation and anion exchange membranes. The main target of this application is to remove the salt from the inlet stream, while the concentrate and by-products are not important and usually disposed.
Using bipolar membranes (BPM) membranes in ED stacks enables not only desalination, but also the efficient transformation of salts into their respective acids and bases.
The required H+ and OH- ions for the acid and base production are provided by water splitting at the bipolar membranes. One current disadvantage of recovery of acids and bases by electrodialysis apart from the relatively high membrane costs is the high energy consumption of the process.
Target of this project was a significant reduction of the energy consumption of ED to make more applications economically feasible. This target was achieved by development and demonstration of novel electrode configurations and materials: The anode and cathode produce oxygen and hydrogen respectively and therefore typically require a total additional voltage of around 1.8 V to 2 V to drive the reactions. With the NovEED electrode concept this voltage loss can be significantly reduced. In addition, the work performed in the project took also the effect of the ion exchange membranes on the process efficiency and energy consumption into account.
The NovEED concept was realized for two different applications:
• Salt splitting (alkaline electrode rinse solutions)
• Acid recovery from metal processing solutions (acidic electrode rinse solutions)

The project partners achieved the following results:
• Modelling of the ED process: A process model based on Comsol simulation allowing future adaptation to new process waters was developed, including the simulation of electrodes and membranes. The work performed can be used to evaluate the electric field and ion concentration profiles as well as the fluid flow distributions in reactors for physical-chemical water separation processes.
• Electrode and catalyst fabrication and characterization: The RTD and SME partners achieved significant progress in the development of catalyst materials especially for oxygen reactions in alkaline electrolytes. Possible applications apart from electrodialysis are electrolysis, fuel cells and batteries.
• Industrial design specifications: Critical parameters for scale-up in size were evaluated.
• Demonstration case studies: The acid recovery process was demonstrated with process solutions from industry. The acid recovery performance was evaluated in terms of energy consumption, current efficiency, and concentration of impurities in the recovered acid.
• Life cycle assessment and economic analysis: The ED process was evaluated by its ecological footprint and compared to the case of acid purchase. In a similar way, a costs analysis was performed, identifying energy consumption and membrane replacement costs as the most important contributions. It could be shown that the reduced energy consumption by the NovEED project has the potential to make the ED technology economically competitive.

The potential application of the NovEED technology is not just limited to the mining and electroplating industry. It has wider potential in all processes in which a process stream or wastewater stream is partially or completely neutralised.

Project Context and Objectives:
Electrodialysis (ED) is an electrochemical membrane process technology which is used especially for desalination of sea or brackish water, e.g. for drinking water supply. In this case, the salt ions of the inlet stream (seawater or brackish water) are separated by an applied electric field and using cation and anion exchange membranes. The main target of this application is to remove the salt from the inlet stream, while the concentrate and by-products are not important and usually disposed.
Using bipolar membranes (BPM) membranes in ED stacks enables not only desalination, but also the efficient transformation of salts into their respective acids and bases.
The required H+ and OH- ions for the acid and base production are provided by water splitting at the bipolar membranes. One current disadvantage of recovery of acids and bases by electrodialysis apart from the relatively high membrane costs is the high energy consumption of the process.
Target of this project was a significant reduction of the energy consumption of ED to make more applications economically feasible. This target was achieved by development and demonstration of novel electrode configurations and materials: The anode and cathode typically produce oxygen and hydrogen respectively and therefore typically require a total additional voltage of around 1.8 V to 2 V to drive the reactions. With the NovEED electrode concept this voltage loss can be significantly reduced.
The project objectives were:
• Electrode and Membrane Modelling and necessary characteristics
• Electrode and catalyst production, characteristics and performance
• Industrial design specification
• Case studies about first field tests

Project Results:
In the NovEED project, two electrodialysis processes and electrode configurations were optimized and characterized: Salt splitting electrodialysis with bipolar membranes using electrodes in contact to alkaline electrode rinse solutions, and acid recovery from metal-containing process solutions using electrodes in acidic environment. The project focused on the optimization of the electrodes for lower energy consumption of the process and on the optimization of the process itself to increase the current efficiency and to reduce parasitic transport of impurities. Main fields of research and technology of the project were:

• Modelling and development of the ED process and its components
The electrodialysis processes were simulated using Comsol Multiphysics software. Current densitiy profiles, ion concentration profiles and ion fluxes around electrodes and membranes could be simulated. By combination of modelling with experimental characterization of ED membrane stacks, the contributions of electrodes, electrolytes and membranes to the energy consumption and efficiency could be determined, which is essential for process optimization

• Electrode and catalyst development
Novel non-noble metal catalysts with high catalytic stability, high electrochemical stability in alkaline electrolytes and low material costs were developed and tested. Electrodes covered with these catalysts were realized and can be used not only for electrodialysis, but also fuel cell or electrolysis applications.

• Construction of ED unit and scale-up
An electrodialysis unit with ED stack, pumping and piping system, sensor unit and control system was constructed and can be used for post-project tests by all NovEED partners.

• Demonstration tests with process solutions
ED demonstration test runs with industrial solutions were performed. The membrane stack was optimized for high selectivity towards the target species. Economic and ecological evaluation (life cycle assessment) was performed to validate the process and to determine the remaining critical challenges which have to be overcome. The evaluation clearly showed that the work performed in the NovEED project is an important step to make ED technology economically competitive in the recovery of chemicals from industrial solutions.

Potential Impact:
The NovEED project results have the following economic and ecological impacts:

Electrode and Membrane Modelling and necessary characteristics

In the NovEED project, a FEM model based on Comsol Multiphysics was developed which enables the simulation of electrodes and ion exchange membranes and their interfaces to the surrounding electrolytes. The project results will enable optimization of electrochemical water treatment and separation processes and significantly reduce the required effort in material, energy and personal costs. The impact of this result is not limited to the application in the NovEED process, but can be adjusted to:

• Other electrodialysis processes
• Electrolysis
• Capacitive deionization

Electrode and catalyst production, characteristics and performance:
In the NovEED project, electro catalysts for efficient oxygen reactions in alkaline electrolytes were developed and characterized. These cheap non-noble metal catalyst materials showed higher electrochemical activity and higher stability than commercially available materials. These catalysts are expected to be of high impact for implementation in electrodialysis, electrolysis and energy storage applications. The project investigated also the use of noble metal catalysts for the use in acidic electrolyte systems. Optimization of the catalyst loading as a trade-off between technical and economic performance was achieved.
The achieved results are essential for the realization of highly energy efficient process, thus reducing the operational costs as well as the ecological footprint of electrochemical processes.

Industrial design specifications:
An electrodialysis unit was developed and constructed. Optimization of the membrane stack and the peripheral components like pumping system, sensing unit, power supply and control system for the application under focus was achieved. The acquired results enable the project partners to scale new technologies from laboratory to industrial scale.

Case studies about first field tests:
It was successfully demonstrated that electrodialysis can be used for the acid recovery from process solutions. Main requirements like low energy consumption and low transport of impurities to the recovered chemicals were met by optimizing membranes and electrodes of the ED stack. Further demonstration tests, especially to validate the longterm stability of the membrane stack for the targeted applications, are planned for the post-project phase.
This result is expected to have significant economic and ecological impact, since the NovEED technology has shown the potential to enable the recovery of chemicals from industrial process solutions. This will reduce the consumption of chemicals and the amount of produced wastewater in industry.

List of Websites:
http://www.noveed.eu/

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Kontakt

Christoph Schulte, (EU Projects Officer)
Tel.: +49 89 1205 2728
Faks: +49 89 1205 7534
Adres e-mail
Numer rekordu: 184139 / Ostatnia aktualizacja: 2016-06-02