Looking for a bachelor or master assignment? Please contact us for the possibilities in the Department of Membrane Science & Technology. Below you will find our vacant student assignments.
- Fabrication of reinforced saloplastic ion exchange membranes
Hestie Brink, Saskia Lindhoud, Wiebe de Vos, University of Twente
Ion exchange membranes (IEMs) are essential components for the efficient operation of a wide range of electrochemical technologies, including electrodialysis, water electrolysis, and fuel cells.1 These non-porous membranes contain a high concentration of fixed charges, which enables the separation of ions based on their charge. Within electrochemical cells, IEMs act as separators between the anode and cathode compartments and are used to regulate the transport of ions based on charge exclusion. IEMs are mainly evaluated based on their ionic resistance and permselectivity, which affect the energy intensity and efficiency of these processes.2 The harsh operating conditions required for specific applications also make chemical stability an important parameter to consider. Consequently, there is a growing need to develop highly conductive membranes that are stable in extreme pH and oxidative environments.
It has recently been demonstrated that sustainable and highly stable ion exchange membranes can be produced through the hot-pressing of non-stoichiometric polyelectrolyte complexes, resulting in so-called saloplastic membranes.3 This simple approach facilitates the fabrication of IEMs using saltwater, thereby eliminating the reliance on toxic solvents typically associated with conventional membrane production methods. Furthermore, saloplastic materials are recyclable which further highlights the sustainability of this approach.
The objective of this project is to enhance the performance of saloplastic anion exchange membranes through reinforcement. By hot-pressing a mesh into the IEM, a thin yet mechanically stable freestanding film can be produced that will minimise the resistance of the membrane. Moreover, the incorporation of hydrophobic mesh materials could potentially reduce membrane swelling, leading to significant improvements in the fixed charge density, and thus membrane performance.
This assignment can be suitable for either bachelor and master students.
If you want to know more about this project, please contact Hestie Brink (h.a.brink@utwente.nl).
References
[1] Ran, J. et al. Journal of Membrane Science 2017, 522, 267-291.
[2] Kitto, D.; Kamcev, J. Journal of Membrane Science 2023, 677, 11-20.
[3] Krishna, A.B. et al. Journal of Colloid and Interface Science 2021, 593, 11-20. - Developing Dense Polyelectrolyte Multilayer Membranes for organic micropollutant removal
Background:
Organic micropollutant (OMP) contamination in water, such as pharmaceuticals, pesticides, and personal care products, is an emerging concern for global water treatment efforts. Although present in trace amounts, these OMPs can be harmful even at very low concentrations. Due to their small molecular sizes, many existing filtration technologies struggle to remove them from water sources effectively. As water scarcity intensifies due to population growth, industrial activities, and climate change, the need for advanced filtration technologies becomes crucial.
Polyelectrolyte Multilayer (PEM) membranes, constructed by alternating layers of positively and negatively charged polyelectrolytes, exhibit unique properties such as tunable pore size, surface charge, and permeability. Current PEM membranes are either highly selective for OMPs or exhibit strong stability, but achieving both simultaneously remains a challenge. This project aims to develop membranes that balance high selectivity and stability to improve overall performance. This project aims to develop dense and stable PEM-based nanofiltration (NF) membranes for surface water treatment by testing novel polyelectrolyte pairs. Additionally, the membranes will be evaluated for their stability and performance in harsh conditions, ensuring they maintain their selectivity and efficacy against micropollutants even after repeated use, leveraging their advanced properties to improve water purification efficiency.
Keywords: Polyelectrolyte multilayers, nanofiltration, dense membranes
During this project, you will focus on:
- Conducting an in-depth review of current literature on PEM membranes, focusing on their working mechanisms, properties, and efficacy in water treatment applications. This review will cover key topics such as the properties of different polyelectrolytes, their ion selectivity behavior, and the latest innovations in PEM membrane technology.
- Fabricate PEM membranes using the layer-by-layer technique, focusing on dense membrane formation to enhance treatment efficiency.
- Performing experiments to evaluate the permeability, salt retention, MP retention, and molecular weight cut-off (MWCO) of PEM membranes.
- Explore symmetric and asymmetric coating configurations for optimized membrane performance.
- Comparing the performance of dense PEM membranes with conventional NF membranes, focusing on improvements in selectivity.
This project is ideal for master's students seeking hands-on experience in advanced water treatment technologies.
For more information, please contact: Sina Rezaei (Sina.rezaei@utwente.nl)
- Metal-organic frameworks (MOFs) for specific ion selective membranes
Metal-organic frameworks (MOFs) are a class of porous hybrid materials that are composed of coordinated metal atoms that are linked to each other via organic linker molecules. This forms porous materials with pores in the order of magnitude of several Angstroms. This property makes MOFs interesting to use as a membrane to separate specific ions from each other, unlike conventional ion-exchange membranes which are primary based on charge-exclusion and show very limited ion-ion selectivity.
Relatively recently, in the field of ion separations in water MOFs became of interest for specific water treatment that needs to target specific types of ions in water that also consists of other less interesting ions that do not need to be removed. Due to these small pore sizes, ions that are transported through the membrane have to dehydrate some shells of water to fit into the MOF pores. Therefore MOF based membranes can separate ions based on how easy they lose their water shells[1,3]. This makes it possible for instance to recovery lithium ions selectively from a saline feed stream and it is possible to create a membrane that is more selective towards monovalent ions compared to multivalent ions (Cl- vs. SO4- or Na+ vs Mg2+) [1,2]. Furthermore it was found specifically for fluoride ions, that specifically bind fluoride to the MOF structure also enhanced the transport through a MOF membranes [3].
In this project we will make MOF modified membranes and will characterize the membrane for instance with SEM and XRD. Furthermore we will analyze the modified ion transport through the MOF membrane with bi-ionic potential measurements and finally we can potentially test how well this membrane works in an electric-driven separation processes to separate specific ions. This project has industrial implications into developing new resource recovery processes in industry of valuable components, such as lithium from seawater.
This assignment can be suitable for either bachelor or master students.
If you’re interested and would like to know more about this project, then don’t hesitate to contact Jeff Wood (j.a.wood@utwente.nl).
[1]: J. Lu et al. Efficient metal ion sieving in rectifying subnanochannels enabled by metal–organic frameworks. Nature Materials 2020 p. 767-774.
[2]: H. Zhang. Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer pores. Science Advances 2018 vol. 4 (2).
[3]: X.Li. Fast and selective fluoride ion conduction in sub-1-nanometer metal-organic framework channels. Nature Communications 2019 vol. 10 (1).
- Effect of a temperature & concentration gradient on the transport of ions through ion selective porous media
Previously, we have researched the influence of temperature gradients on the performance of electrodialysis experimentally [1,2] as well as numerically with a model system of ion selective nanochannels [3]. It was found that temperature differences can increase current at a given voltage (as expected from conductivity) and more interestingly that ion selectivity could be tuned based on these temperature differences due to variation in how the hydrated radius of ions change at different temperatures.
However, in an electrodialysis process, the salt concentration changes along the length of the membrane due to the electrical field, which drives the ions through the ion-exchange membrane. Therefore, more fundamental research into the effect of temperature and concentration gradients on the transport rate of ions through a membrane is necessary to exploit these effects.
In this work, we plan to study ion and related transport phenomena through a bed packed with ion-exchange resin particles, while keeping the temperature gradient and concentration gradient nearly constant across the bed. Ion exchange resin particles are composed of charged groups and therefore will preferentially allow the transport of counterions through the bed, while co-ions are retained by the ion exchange resin, which mimics a ion-exchange membrane. This setup allows to study the effect of concentration difference, electrical field strength, etc. on the rate of transport of different ions through porous ion exchange beds. This then has possible implications in how to improve industrially scale ion-exchange processes using low-grade waste heat.
This assignment can be suitable for either bachelor and master students.
If you’re interested and would like to know more about this project, then don’t hesitate to contact Jeff Wood (j.a.wood@utwente.nl).
[1]: A. Benneker et al. Effect of temperature gradients in (reverse) electrodialysis in the Ohmic regime. Journal of Membrane Science 2018 p. 421-428.
[2]: A. Benneker et al. Influence of temperature gradients on mono- and divalent ion transport in electrodialysis at limiting currents. Desalination 2018 p. 62-69.
[3]: A. Benneker et al. Influence of temperature gradients on charge transport in asymmetric nanochannels. Physical Chemistry Chemical Physics 2017 vol. 19 (41).
- Characterization of physicochemical changes in membranes in the valorization of food waste
Are you interested in contributing to the reduction of food waste? Do you like to understand how the chemistry and properties of membranes change when exposed to different environments? Then this project is for you.
Food systems are responsible for one third of the greenhouse gas (GHG) emissions (Crippa et al. 2021) and in the current food production systems 30-50% of food is wasted. To be able to feed the growing population (10 billion people by the decade of 2050 (United Nations 2022)) in a sustainable manner, recovering ingredients from food waste has become one of the priorities of governmental organizations and private companies, as most of this waste is perfectly edible and presents high nutritional value (e.g. proteins, sugars, etc.). The production of ingredients from food side streams is known as upcycling.
In this project, Greencovery and the Membrane Process Technology group of the University of Twente work together to understand how we can use membranes to reduce the energy consumption during the upcycling of food side streams. The project is part of a research consortium involving several companies (Recircanol: https://ispt.eu/projects/recircanol/).
During the standard upcycling process ethanol is recovered using traditional methods like evaporation and distillation. Implementing membranes would help to reduce the environmental impact and production cost of the process. However, the ethanol containing stream also has a high pH, which presents a challenge for traditional organic solvent resistant/tolerant nanofiltration membranes (Othman et al. 2010). Therefore, further research is needed to implement membranes in the solvent recovery step.
MSc student assignment
The objective of this assignment is to understand how the structures and properties of different commercially available nanofiltration membrane materials change when processing ethanol-water-hydroxide mixtures.
During the project you will perform the experiments, evaluate the obtained data and interpret the results. The assignment involves physicochemical characterization of the membranes using advanced techniques (like electronic microscopy (SEM), ellipsometry, streaming potential, chromatography). Also, you will develop your soft skills (time and stakeholders management, oral and written communication, independence and initiative).
The project will take place in the facilities of the Department of Membrane Science and Technology at the University of Twente.
This assignment is suitable for master students.
If you’re interested and would like to know more about this project, then don’t hesitate to contact Paco Caparros (f.caparrossalvador@utwente.nl).
- Crippa, M., E. Solazzo, D. Guizzardi, F. Monforti-Ferrario, F. N. Tubiello, and A. Leip. 2021. “Food Systems Are Responsible for a Third of Global Anthropogenic GHG Emissions.” Nature Food 2 (3): 198–209. https://doi.org/10.1038/s43016-021-00225-9.
- Othman, Rahimah, Abdul Wahab Mohammad, Manal Ismail, and Jumat Salimon. 2010. “Application of Polymeric Solvent Resistant Nanofiltration Membranes for Biodiesel Production.” Journal of Membrane Science 348 (1): 287–97. https://doi.org/10.1016/j.memsci.2009.11.012.
- United Nations. 2022. “World Population Prospects.” Summary of results. New York. https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/wpp2022_summary_of_results.pdf.
- Evaluation of solvent-resistant NF membranes for the recovery of food ingredients
Are you interested in contributing to the reduction of food waste? Do you like to understand how the chemistry and properties of membranes change when exposed to different environments? Then this project is for you.
Food systems are responsible for one third of the greenhouse gas (GHG) emissions (Crippa et al. 2021) and in the current food production systems 30-50% of food is wasted. To be able to feed the growing population (10 billion people by the decade of 2050 (United Nations 2022)) in a sustainable manner, recovering ingredients from food waste has become one of the priorities of governmental organizations and private companies, as most of this waste is perfectly edible and presents high nutritional value (e.g. proteins, sugars, etc.). The production of ingredients from food side streams is known as upcycling.
In this project, Greencovery and the Membrane Process Technology group of the University of Twente work together to understand how we can use membranes to reduce the energy consumption during the upcycling of food side streams. The project is part of a research consortium involving several companies (Recircanol https://ispt.eu/projects/recircanol/).
During the standard upcycling process ethanol is recovered using traditional methods like evaporation and distillation. Implementing membrane technology would help to reduce the environmental impact and production cost of the upcycling process. However, the ethanol containing stream also has a high pH, which presents a challenge for traditional organic solvent resistant/tolerant nanofiltration membranes (Othman et al. 2010). Therefore, further research is needed to implement membranes in the solvent recovery step.
BSc or MSc assignment
The assignment's objective is to evaluate the behavior and performance of different commercially available (nanofiltration)membranes on laboratory scale (focusing on flux, rejection), and to determine the impact of these changes on the process design.
During the project you will perform the experiments, evaluate the obtained data and interpretate the results. Also, you will develop your soft skills (time and stakeholders management, oral and written communication, independence and initiative).
The project will take place in the facilities of the Department of Membrane Science and Technology at the University of Twente.
This assignment is suitable for both bachelor and master students.
If you’re interested and would like to know more about this project, then don’t hesitate to contact Paco Caparros (f.caparrossalvador@utwente.nl).
- Crippa, M., E. Solazzo, D. Guizzardi, F. Monforti-Ferrario, F. N. Tubiello, and A. Leip. 2021. “Food Systems Are Responsible for a Third of Global Anthropogenic GHG Emissions.” Nature Food 2 (3): 198–209. https://doi.org/10.1038/s43016-021-00225-9.
- Othman, Rahimah, Abdul Wahab Mohammad, Manal Ismail, and Jumat Salimon. 2010. “Application of Polymeric Solvent Resistant Nanofiltration Membranes for Biodiesel Production.” Journal of Membrane Science 348 (1): 287–97. https://doi.org/10.1016/j.memsci.2009.11.012.
- United Nations. 2022. “World Population Prospects.” Summary of results. New York. https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/wpp2022_summary_of_results.pdf.
- CFD simulations to assess the influence of flow cell geometry on NF membrane performance
Are you interested in contributing to the reduction of food waste? Do you like to understand how the chemistry and properties of membranes change when exposed to different environments? Then this project is for you.
Food systems are responsible for one third of the greenhouse gas (GHG) emissions (Crippa et al. 2021) and in the current food production systems 30-50% of food is wasted. To be able to feed the growing population (10 billion people by the decade of 2050 (United Nations 2022)) in a sustainable manner, recovering ingredients from food waste has become one of the priorities of governmental organizations and private companies, as most of this waste is perfectly edible and presents high nutritional value (e.g. proteins, sugars, etc.). The production of ingredients from food side streams is known as upcycling.
In this project, Greencovery and the Membrane Process Technology group of the University of Twente work together to understand how we can use membrane technology to reduce the energy consumption during the upcycling of food side streams. The project is part of a research consortium involving several companies (Recircanol https://ispt.eu/projects/recircanol/).
During the standard upcycling process, ethanol is recovered using traditional methods like evaporation and distillation. Implementing membrane technology would help to reduce the environmental impact and production costs of the process. However, the ethanol containing stream also has a high pH, which presents a challenge for traditional organic solvent resistant/tolerant nanofiltration membranes (Othman et al. 2010). Therefore, further research is needed to implement membranes in the solvent recovery step.
BSc or MSc assignment
The objective of this assignment is to use computational fluid dynamics (CFD) to understand the impact of module configuration on the membrane performance (flux, rejection) and overall nanofiltration process when working with ethanol-water-hydroxide mixtures.
You will simulate chemical species transport and fluid flow patterns for different membrane cell geometries, compare the simulation results with experimental data, and interpretate the results. Also, you will develop your soft skills (time and stakeholders management, oral and written communication, independence and initiative).
The project will take place in the facilities of the Department of Membrane Science and Technology at the University of Twente.
This assignment is suitable for either bachelor or master students.
If you’re interested and would like to know more about this project, then don’t hesitate to contact Paco Caparros (f.caparrossalvador@utwente.nl).
- Crippa, M., E. Solazzo, D. Guizzardi, F. Monforti-Ferrario, F. N. Tubiello, and A. Leip. 2021. “Food Systems Are Responsible for a Third of Global Anthropogenic GHG Emissions.” Nature Food 2 (3): 198–209. https://doi.org/10.1038/s43016-021-00225-9.
- Othman, Rahimah, Abdul Wahab Mohammad, Manal Ismail, and Jumat Salimon. 2010. “Application of Polymeric Solvent Resistant Nanofiltration Membranes for Biodiesel Production.” Journal of Membrane Science 348 (1): 287–97. https://doi.org/10.1016/j.memsci.2009.11.012.
- United Nations. 2022. “World Population Prospects.” Summary of results. New York. https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/wpp2022_summary_of_results.pdf.