When Dr. Adrian Monteleone begins to talk about his current progress in the development of his polymer adsorbents, the sentences just bubble out of him.He starts to enthuse even more when he is asked what he has in mind for the future.The biotechnologist knows about the potential of numerous plastics for industrial applications, but also about their potential to bind pollutants and trace substances, as the toxicology of microplastics is his area of expertise.
Microplastics accumulate toxins; microplastics are known and feared by society for this.But what if this supposed disadvantage were turned into an advantage? What if microplastics were used in a controlled and targeted manner?
It was precisely this idea that sparked Monteleone's start-up PolymerActive. Together with his team, he wants to actively use polymers for the filtration of pollutants and trace substances and beyond. This not only enables him to upcycle hazardous waste, but also to reduce the use of activated carbon filters in many areas, with the long-term goal of avoiding activated carbon altogether.
The use of activated carbon is comparatively harmful to the climate, but is currently indispensable. There is a lack of alternatives - yet.Activated carbon is usually obtained by carbonizing carbon-rich plant material (such as hard coal, charcoal, coconut fibres, peat) or from open-cast mines as lignite. The coal is then treated at temperatures of up to 900°C, often with the addition of gases or chemical activation to further increase its surface area.
Adrian Monteleone gives value to hazardous waste that would otherwise only be incinerated.He has developed a manufacturing method to turn them into customized filters for any application and any cocktail of pollutants.
THE PRODUCTION OF HYBRID ADSORBENTS
Monteleone wants to produce so-called hybrid adsorbents from special plastic waste. This involves adsorption, not absorption: During adsorption, molecules dock onto the surface of the plastic and are bound in this way instead of wandering around in the air. In order for as many molecules as possible to dock, there must be many docking points. The surface of the plastic waste must not be smooth. As with activated carbon, the same applies to plastics: the rougher the surface, the larger it is and the more pollutants and trace substances it can absorb. However, the surface area of the special plastic waste delivered to PolymerActive is too small. To change this, Monteleone and his team have developed a patent-pending process.
In simple terms, the plastic waste is first liquefied and then brought into the desired shape using a dripping device by precipitating and hardening the liquefied polymers.
The desired form can vary from powder, beads or threads to membranes. Crucially, Monteleone has managed to massively increase the surface area of the newly formed polymers using his process - and thus also the filter performance.For example, a sample weighing one gram already has a surface area of up to 338 square meters in its current state of development.
Adsorbents at 10000x magnification with increased porosity and specific surface area.
Surfaces of a physico-chemically modified plastic waste
In addition to increasing the surface area, Monteleone has a second goal that he wants to achieve with his polymer filter material: the functionalization of the surfaces.
Each polymer binds other molecules, either directly or indirectly. This means that Monteleone can either filter out pollutants that bind directly or he can use bridge molecules: Bridging molecules bind polymer filters on one side and pollutants on the other. As a result, the polymer filter with the bridge molecule has been converted in such a way that it filters pollutants and trace substances that previously could only be filtered with considerable effort or not at all, e.g. heavy metals such as lead, copper and cadmium, but also organic compounds such as phenols, aromatic hydrocarbons and pesticides. The polymer filters can therefore filter out pollutants for which activated carbon fails or which can only be filtered at high cost using other methods.
FUNCTIONALIZATION OF SURFACES
The potential:
Use of polymer filters
The use of a polymer filter offers particular advantages in the purification of digester gases and could also be used for the filtration of molecules in flue gases in the future. This technology is becoming increasingly important as ever stricter environmental regulations pose challenges for the operators of waste incineration plants: They must comply with legal limits while minimizing cost increases. But Monteleone's filter technology can also help with the filtration of building pollutants; in particular where buildings are threatened with demolition, the costs of new buildings and the associated CO2 emissions could be saved in future. In addition, he has already been able to prove that the filter material can be used in the case of particular indoor pollution, e.g. for filtering volatile organic compounds from the exhaust air of production processes.
In addition to environmental purification, the polymer filters also allow the filtered substances to be recovered for reuse as raw materials in a second process step. In addition, the polymer filter can be reused several times after a treatment process. Although activated carbon can also be reprocessed, this process is relatively complex and can only be repeated to a limited extent.
Monteleone's work will help to give special plastic waste a second, more valuable life. His process is the first known large-scale production process for polymer adsorbents from plastic waste and can also be used for biological adsorbents. This means that combinations of biological and synthetic hybrids are also possible and the polymer filters can be precisely tailored to the pollutant mix to be filtered.