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Nano-particle catalysts supported on natural polymers. They continuously and passively degrade ethylene at room temperature without needing maintenance or energy.
About
The effectiveness of a chemical catalyst is directly correlated to it's surface area. Nanoparticles have very high surface area to mass ratios and so can make exceedingly effective catalysts. However, their small size also can cause individual particles to aggregate, thus lowering the surface area available for catalytic activity. The PolyCatUK process allows us to form effectively immobilised nanoparticles on polymeric substrates ranging from polyethylene to PTFE, and natural polymers such as wood flour. This process allows us to present the nanoparticles in a novel way, with particular benefits on high surface area substrates such as the microporous polymer materials used in air filters or water treatment. Ethylene is a gas emitted from most fruits as they ripen. It reacts with nearby fruit and then hastens the ripening process, leading to a chain reaction of ripening. In a sealed environment (i.e. a fridge, shipping container or punnet) the ethylene can build up and cause the over-ripening of any nearby fruit. A container of blueberries from Chile will spend on average three weeks in a shipping container before it reaches a UK packaging plant. However, on average 25% of each container imported from outside Europe will be over-ripe, and unsuitable for retail sale. This amounts to approximately 350,000 tonnes of fruit wasted every year due to UK import alone. This wastage forces both fruit suppliers and supermarket retailers to over-order, leading to higher economic and environmental costs. The PolyCatUK process has enabled us to create a reusable catalyst that can continuously and effectively degrade ethylene in it's surroundings. As the PolyCatUK product utilises catalysis, it could operate continuously for at least six months. After that period it would only require a simple steam-clean before being once again ready for use. The PolyCatUK catalyst would also have low initial production costs. As we are able to immobilise the catalytic nanoparticles in a distribution that maximises their surface area, the amounts of catalytic material required is minimal. Early trials have shown that our prototype catalysts can extend the shelf life of various fruits, with blueberries in sealed punnets showing an extension of three - five days. We have partnered with a multi-national fruit supplier to run a series of ongoing trials on further fruit in various environments.
Key Benefits
Other existing products attempt to reduce ethylene levels in containers through single-use absorbing strips or sachets. Each strip can only absorb a set amount of ethylene and then must be disposed of. The capacity of each strip is also dramatically reduced in humid environments. Most single-use products also include KMnO4 (potassium permanganate), a hazardous material considered very toxic to aquatic life. The PolyCatUK product also reduces the quantity of ethylene in the fruit’s vicinity. However, rather than absorbing it, the ethylene is converted into other harmless products, meaning the catalyst can function indefinitely without a significant reduction in efficacy. This approach would not require any implementation or maintenance costs as the catalyst must simply be placed near the targeted fruit and then will continue to remove ethylene from its environment until it eventually degrades. The catalyst should be able to function continuously for an extended period before requiring a simple steam clean, leading to a reduced production and environmental cost compared to less cost efficient and wasteful single-use solutions. Furthermore, any product produced using this process would be hydrophobic due to its polymeric nature, and so should not be adversely affected by humidity unlike existing solutions. In summary, the PolyCatUK product would offer comparable shelf life extension (with our existing prototype already showing a regular 3 day extension in the shelf life of blueberries post packaging) for a lower cost whilst mitigating many of the environmental and practical downfalls of existing products.
Applications
This product is aimed specifically at extending the shelf life of fruit from harvest to the point of packaging. Our existing prototype is a small disk that can be placed with containers of fruit and then continuously degrade any ambient ethylene, reducing the rate of ripening until it is removed. We are also exploring ink based and sticker based catalysts for use in post packaging preservation. The PolyCatUK process does have several other applications including catalytic filters that could degrade VOCs, removing certain pollutants from water supplies and a defence and security application that is currently under development..