"spongy" nanomaterial may change the way to monitor water quality

A group of researchers at the Ecole Polytechnique (EP) in Palaiseau, near Paris, have developed a tiny film that could speed up the process dramatically. The "nano-factor" is within the film itself: billions of nanopores per square cm 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, Technology Transfer Officer at the Ecole Polytechnique, is an engineer with industry experience who is supporting the team that developed the sensor. The team include Marie-Claude Clochard, Travis Wade and Haad Bessbousse

How does your system work?
Research teams and companies around the world are developing membranes to filter water. Our researchers realized that we could adapt 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 can 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 pumped 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.

The 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, surface waters from a lake or river, 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 amongst others 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, KWR, the EP and other companies have formed a consortium and have recently applied for an EU grant.

Bram van der Gaag is a scientific researcher for "Monitoring and sensoring" at 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- and surface- and waste waters 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 an 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.
6 March 2012

Sergio Pistoi

For details contact Ms Elisabeth Schmid: elisabeth.schmid@youris.com; www.youris.com
ProNano (Promoting Technology Transfer of Nanosciences, Nanotechnologies, Materials and new Production Technologies, SA funded by the European Commission DG RTD – FP7 NMP, Project Reference 248219). http://www.pronano.eu

see also http://www.youris.com with articles about EC projects Nanocom and Pronano