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A group of French researchers has developed a nanomaterial that works like a sponge for some water pollutants and allows to measure them easily and quickly
Heavy metals coming from industrial waste, such as mercury, lead, cadmium, nickel, and zinc are some of the most dreaded pollutants in water, and EU laws strictly limits their concentration in the water we drink. Measuring these pollutants is commonplace but cumbersome. A sample of water has to be collected and taken to a laboratory for analysis, and results typically require days or weeks.
A group of researchers from the Ecole Polytechnique in Palaiseau, near Paris, have developed a tiny film that could speed up the process dramatically. The "nano-factor" is within the film itself: millions of nanopores that trap metals like a sponge, making them immediately available for analysis. Their new system is portable, provides immediate results, and therefore may change the way we monitor water quality.
François Plais is an engineer with industry experience at the Ecole Polytechnique and a member of the team that developed the sensor.
How does your system work?
At the beginning we were developing a membrane to filter water, not to analyse it. Then we realized that we could change the structure of the membrane to work as a trap for metal ions. The two ideas are similar and opposite: a filtering membrane is a tiny sheet of polycarbonate with holes of a diameter of 30-40 nanometers, called nanopores, that let the water flow and filter out impurities. Our sensor membrane, instead, is made with another polymer called PVDF, and with nanopores that trap water and any metal ions that come with it. Basically, it works like a sponge. The system also works as a sensor, because metals ions change the electrical properties of the membrane. If we apply two electrodes at the membrane, we can measure the concentration of metals with a standard electrochemical test, which is relatively straightforward.
What are the advantages compared to the existing technologies?
With our system you don't need to bring a sample to the laboratory, because you use it on site. At the same time, our data show that the sensitivity and accuracy are comparable to the current laboratory standards.
Can you mention some possible applications ?
Our system may be ideal to assess the quality of drinking water from lakes, reservoirs or rivers, for example, or to monitor pollution from industrial waste. By providing immediate results, it could really change the way we monitor water quality, as far as heavy metals are concerned.
What are you going to do next?
We still need to validate our laboratory results in a real-world setting. With the help of Pronano, we have found a partner that will allow us to do that, and we are now working on this new phase of the project.
When the group of researchers at the Ecole Polytechnique (EP) created the new nanomaterial-based sensor for monitoring heavy metals in drinking water, they turned to the EU funded project Pronano for help and advice to address a crucial question: their prototype works well in the laboratory, but how will it perform in the real-world? Before they can foresee commercial applications, researchers need to be sure that their sensor can work and be accurate in actual applications, such as monitoring drinking waters from a lake, or wastewaters from an industry.
To resolve this issue, the Pronano consortium matched the French group with the KWR Watercycle Research Institute, a Dutch company specialized in methods to ensure water quality. Because of its technical know-how and knowledge of the water market, KWR is a suitable partner to test the technology developed at the EP and bring it to the market. To this aim, the KWR, the EP and other companies have formed a consortium and have recently applied for a EU grant.
Bram van der Gaag is a researcher for "Monitoring and sensoring" at the KWR and is working with the French group for the project.
How did you get involved in this work?
The process was fairly straightforward. I got a call from Technofi, a partner of Pronano, who asked me if we were interested in testing the technology that the EP had developed. I wanted to visit the EP before deciding, and when I saw their work I became convinced that it could work. It's an elegant solution, and you have immediate results, because you measure the metal concentrations right away on the sample. If it works, it may be a breakthrough for the water industry.
What kind of "real-life" testing are you planning to do?
We are planning to collaborate with some companies that routinely perform water monitoring in different environments. We will use the new sensor to monitor drinking waters and wastewaters at different times and in different situations. To verify the accuracy of data, we will compare the results from the sensor with that obtained with standard laboratory methods.
If this technology works, how do you think it may change the water industry?
This type of sensor may be a dramatic improvement for decentralized purification systems, since it is portable and gives real-time results. Decentralized systems are common in many countries such as India, for example. Eventually, manufacturers may want to embed these sensors in products such as boilers or coffee makers to check for water quality in real-time.
Fonte: Cordis Wire
