Researchers from the Institute of Materials Science and Engineering at Lodz University of Technology have developed an innovative technology to produce graphene electrodes for water treatment. Thanks to the use of a new coating they have obtained electrodes that are much more durable in use and, what is most important, much cheaper. Prof. Konrad Dybowski from the Faculty of Mechanical Engineering, project manager, talks about the invention.
Where did you get the idea to use graphene for electrodeposition of water?
Graphene, due to its unique properties, including exceptionally good electrical conductivity, high mechanical properties, chemical resistance and, as it turned out, electrochemical resistance, is perfect for this solution. The key issue was to provide it with a suitable carrier substrate. We decided to use carbon fibres that are bonded with epoxy resin, which gave us the possibility to obtain good adhesion of the produced graphene coating to such a substrate.
Why did your research team use reduced graphene oxide to coat the electrodes, and not monolayer large-surface graphene, the production method of which you have also developed and patented at the Institute?
Primarily because of the difficulty in transferring such large graphene sheets to the electrode surface without defecting them. Moreover, electrodes covered with a monolayer of graphene would be comparable in price to titanium electrodes covered with oxides or platinum. Covering the electrode surface with reduced graphene oxide, which is obtained from graphene oxide, which in turn is obtained from graphite, ultimately gives: firstly, the possibility of easily obtaining such a coating on the electrode, and secondly, a low cost of making it. In relation to currently used titanium electrodes covered with rare earth oxides or platinum, the costs are several times lower.
What is the innovation of the water treatment technology developed by your team?
The process of electrodeionisation of water, as this method is the subject of the invention, has been known for many years. It is primarily a method allowing for obtaining ultra-pure water, used mainly in the electronics, pharmaceutical and energy industries. Our solution, i.e. electrodes made of carbon fibres covered with cross-linked, reduced graphene oxide, combines the advantages of both previous solutions, i.e. using graphite or titanium electrodes, and additionally we have obtained their high durability and relatively low price. In addition, in our technology both electrodes can be made of the same material, which gives the possibility to work in cycles, with periodically changed polarity, and this allows to clean the device for electrodeposition of water from accumulated ions.
The advantage of this carbon composite material is also the possibility of making an electrode with a small thickness (tenths of a mm), while maintaining high mechanical strength. This, in turn, allows multiple pairs of electrodes to be placed in a single water electrodeposition device, instead of just the two outermost ones, as is currently the case with metal electrodes, which could improve the efficiency of these devices.
What properties do graphene-coated electrodes have?
Composite electrodes made from carbon fibres coated with cross-linked, reduced graphene oxide exhibit high resistance to degradation associated with gas evolution at the cathode and anode, as well as high chemical and electrochemical stability over a wide pH range and resistance to oxidation. They are characterised by low resistance, fast sorption and desorption of ions, as well as low susceptibility to organic contamination. Moreover, the use of carbon fibre preimpregnates as a support substrate provides greater durability and gives the possibility to form and retain the formed shapes of the electrodes by epoxy resin polymerisation without the need for additional moulds.
Has the invention already been patented?
Yes, the title of the patent is: Method of manufacturing composite electrodes for electrodeionisation of water based on cross-linked graphene oxide. We obtained patent protection in 2021. The creators are employees, doctoral students and students of our university, as well as employees of the company - a consortium member that collaborated with us on the development of this solution. They are: Konrad Dybowski, Łukasz Kaczmarek, Piotr Kula, Witold Szymański, Tomasz Warga, Grzegorz Romaniak, Bartosz Bucholc, Magdalena Makowicz, Jan Siniarski, Tomasz Kaźmierczak
Where will the new technology from Lodz University of Technology be used?
As I mentioned earlier, the new technology may find application in systems for electrodeionisation of water, to be precise, for production of electrodes for water treatment systems, mainly for industrial purposes, where water of very low conductivity is required. It can also be used in systems to obtain water of a specific composition, where the right mineral content determines the taste, for example. Such water could be used to brew coffee or tea to extract the best possible aroma. I also believe that these electrodes could find application in other electrochemical processes used in industry.
The research was carried out with financial support from European funds. This was a research and implementation project, who is the partner from industry? What funding was provided to carry out the research?
The research was carried out as part of the project 'Graphene-based composite materials for water treatment'. The project was realised in a consortium in which Lodz University of Technology was the leader. The industrial partner (consortium member) was Amii Sp. z o.o., a company from Lodz involved in the production of water filters. Therefore, we have two possibilities for commercialisation of research results. One of them is implementation at our industrial partner, the second path is implementation under the terms of non-exclusive license or exclusive rights in another company.
Implementation plans are somewhat complicated by the current economic and geopolitical situation, but we are counting on the success of this undertaking. Involved in the activities is the Centre for Innovation and Entrepreneurship, Technology Transfer Section, which undertook the valuation of the patent and search for companies. The total value of the completed project was PLN 5,928,412 including EU funding from the Operational Programme Intelligent Development 2014-2020 of PLN 5,132,774.
Interviewed by Małgorzata Trocha.