Periodic Reporting for period 1 - MOSAIC (Building charge-MOSAIC nanofiltration membranes for removing micro-pollutants from surface and drinking water)
Berichtszeitraum: 2023-09-01 bis 2026-02-28
Our surface and drinking water sources are increasingly threatened by the presence of organic micropollutants (OMPs). OMPs are small molecules (100-1000 Da) that originate from industrial, agricultural and pharmaceutical residues, and can cause long-term harm to humans and ecosystems. While OMPs can be removed from water with existing membrane technologies (e.g. reverse osmosis), these methods have significant limitations: they are energy-intensive and lead to problematic brine waste streams, due to their low water and salt permeability.
In this project we aim to solve these limitations by building charge-mosaic membranes; membranes with small (nm2) oppositely charged patches that allow coupled passage of negative and positive ions. This design, aimed at reducing salt retention, was conceived over 90 years ago, but was never realized in a scalable manner due to its challenging design. Here, we propose a simple and fully scalable approach to achieve such membranes, using polyelectrolyte multilayers (PEMs) of oppositely charged polymers. By adding charged nanoparticles to the final layer and then removing them by changing the pH, nanoscale charged patches are created in an oppositely charged surface. We will apply the same principle to create charged channels across the entire multilayer, by using sacrificial polymers. This approach, sacrificially patterned PEMs, allows exceptional control over the size and ratio of the charged patches. We will build these charge-mosaic membranes using ultrathin, ultradense layers in an asymmetric PEM approach to achieve a very high (> 99%) retention of OMPs and a high water permeability.
Combined with state-of-the-art modelling, this project will also provide new fundamental insights into membrane mass transport. Moreover, the project will directly lead to membranes with unique separation properties, allowing the design of completely new processes to effectively remove OMPs from waste water and drinking water.
In this project we aim to solve these limitations by building charge-mosaic membranes; membranes with small (nm2) oppositely charged patches that allow coupled passage of negative and positive ions. This design, aimed at reducing salt retention, was conceived over 90 years ago, but was never realized in a scalable manner due to its challenging design. Here, we propose a simple and fully scalable approach to achieve such membranes, using polyelectrolyte multilayers (PEMs) of oppositely charged polymers. By adding charged nanoparticles to the final layer and then removing them by changing the pH, nanoscale charged patches are created in an oppositely charged surface. We will apply the same principle to create charged channels across the entire multilayer, by using sacrificial polymers. This approach, sacrificially patterned PEMs, allows exceptional control over the size and ratio of the charged patches. We will build these charge-mosaic membranes using ultrathin, ultradense layers in an asymmetric PEM approach to achieve a very high (> 99%) retention of OMPs and a high water permeability.
Combined with state-of-the-art modelling, this project will also provide new fundamental insights into membrane mass transport. Moreover, the project will directly lead to membranes with unique separation properties, allowing the design of completely new processes to effectively remove OMPs from waste water and drinking water.
Several interesting activities have already been pursues in this project:
Membrane Design:
We have designed new polyelectrolyte multilayer based membranes, where a sacrificial nanoparticles on top of the membranes were shown to allow control over ionic separations. Moreover, by embedding the same nanoparticles at the bottom of the layer, we have shown that extremely thin PEM coatings can be achieved that allow for ecellent separation performance at double(!) the water flux. This is a major breakthrough as this would allow effective water treatment at half the energy costs that are now required. Moreover we have found that by making PEM based membranes more hydrophobic, we an achieve denser membranes with very high rejections of organic micro-pollutants.
Modules design:
A new modules has been developed, in which we combine positive and negative membranes. Either as separate fibers, or as half positive and half negative fibers. This again allows for more control over the ion retention, while retaining the good rejections that we find for the organic micro-pollutants.
Theoretical descriptions:
We are developing a new COMSOL based theoretical framework that combines Donnan and Di-electric exclusion to allow effective modeling of charge mosaic membranes.
Membrane Design:
We have designed new polyelectrolyte multilayer based membranes, where a sacrificial nanoparticles on top of the membranes were shown to allow control over ionic separations. Moreover, by embedding the same nanoparticles at the bottom of the layer, we have shown that extremely thin PEM coatings can be achieved that allow for ecellent separation performance at double(!) the water flux. This is a major breakthrough as this would allow effective water treatment at half the energy costs that are now required. Moreover we have found that by making PEM based membranes more hydrophobic, we an achieve denser membranes with very high rejections of organic micro-pollutants.
Modules design:
A new modules has been developed, in which we combine positive and negative membranes. Either as separate fibers, or as half positive and half negative fibers. This again allows for more control over the ion retention, while retaining the good rejections that we find for the organic micro-pollutants.
Theoretical descriptions:
We are developing a new COMSOL based theoretical framework that combines Donnan and Di-electric exclusion to allow effective modeling of charge mosaic membranes.
Three of our results so far are believe to have a real potential for impact:
1. The more hydrophobic PEM coatings allow for a much higher removal of organic micro-pollutants than is so far possible with commercial hollow fiber nanofiltration membranes. We are pursuing this further by discussing with membrane companies and waste water companies.
2. The sacrificial nanoparticle approach that allowed for a strongly improved (double) membrane flux would be a big breakthrough. Still, we would need to demonstrate the scalability of our approach. At the moment we are cnsidering to write a ERC proof of concept grant to push this idea further.
3. The smart module approach where positive and negative fibers are combined would allow companies to tune the retention properties of their modules to any application. We are discussing it with interested parties.
1. The more hydrophobic PEM coatings allow for a much higher removal of organic micro-pollutants than is so far possible with commercial hollow fiber nanofiltration membranes. We are pursuing this further by discussing with membrane companies and waste water companies.
2. The sacrificial nanoparticle approach that allowed for a strongly improved (double) membrane flux would be a big breakthrough. Still, we would need to demonstrate the scalability of our approach. At the moment we are cnsidering to write a ERC proof of concept grant to push this idea further.
3. The smart module approach where positive and negative fibers are combined would allow companies to tune the retention properties of their modules to any application. We are discussing it with interested parties.