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Global waste has been a big issue for several years and continues to be an increasingly pressing issue in modern-day society. In a completely different aspect of the world, the graphene industry has been trying to bolster many sectors, including consumer-centric sectors. However, some applications have not yet been as fruitful (even though the added value is there) because graphene's cost for these industries is currently too high.
A new graphene production method has now emerged that could take your average household carbon-rich waste (as well as other carbon-rich materials) and turn them into graphene in a ‘flash’ (i.e. a hundred milliseconds). This process of turning any other carbon-rich material into graphene is known as Flash Joule Heating (FJH) and was first developed by James Tour at Rice University. It is now commercially developed by Universal Matter.
Compared to other methods out there, such as top-down exfoliation from graphite and bottom-up CVD deposition using methane, the flash graphene process costs are much lower and could be used to create vast volumes of graphene. This is because there is a lot of carbon ‘precursor’ waste in existence that could be eradicated and used to produce graphene. This process has the potential to reduce the cost of graphene and improve the environmental impact of the graphene industry and end-use sectors.
The Flash Graphene Process
The flash graphene process takes any carbon-rich material, treats it with a high current and high-voltage pulse for a hundred milliseconds, and fresh graphene is produced. The process can be used with carbon-based human waste, including household waste, plastic bottles and food, as well as naturally occurring carbon sources such as biochar, coal and petroleum coke.
The result of the process is a highly pure 1-5 layered graphene product with no contaminants. It would be easy to think that converting waste would leave behind trace elements as impurities but that is not the case. The high temperature generated breaks every chemical bond between atoms, breaking everything down to its atomic constituents. The high temperature causes all the other elements except carbon to sublime out (when they go straight from a solid to a gas) as the sublimation temperature for carbon is a few hundred Kelvin higher than the other elemental constituents found in general waste.
For example, within plastic waste, the oxygen atoms will be removed as water or carbon dioxide. The nitrogen atoms will come out as nitrogen dioxide and even the chlorine atoms in PVC can be removed (via HCl formation gas). These by-products can all be captured and used for other purposes. As carbon is the only element left after the ‘flashing’, it forms into its most stable form, and that is graphene.
Aside from producing cheaper graphene, the flash graphene process also offers an alternative approach to plastic recycling. Most recycling methods require the plastics to be sorted (by hand with sensors) and washed multiple times, making recycling processes cost-prohibitive. With the flash process, there is no need to sort the plastics, and they can all be broken down a lot easier and quicker than other plastic recycling methods.
Bringing Down the Cost of Graphene
The ability to create graphene from household waste negates one of the highest costs within the production process—the cost of the raw graphite products used in the exfoliation processes (which can be $1000-3500 per ton, compared to coal, which is $25 a ton). Compared to CVD processes, it is also a much cheaper and less-complex method. Because of these two factors, the flash graphene method can produce much cheaper graphene, and the only main cost is the electricity required to power the flash process.
The cost to produce vary depending on the carbon-levels of the precursor material, but all waste and natural carbon resources could create graphene for less than $100 of electricity per ton. The coal and petroleum coke tend to be on the higher end (but are cheap to buy), whereas household plastic waste can be flashed for around $30 per ton (and is readily available).
Making graphene from trash in less than a second
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Compared to traditional graphite exfoliation methods, there is less energy input and raw material costs, and this could help to drive down the cost of graphene. There are processing stages that add to the cost beyond the $100 mentioned. However, as graphene currently ranges at anywhere between $67,000 and $200,000 a ton, there is a lot of potential to significantly reduce the cost of graphene products—perhaps, by even up to an order of magnitude.
Costs reductions are not down to Universal Matter alone, as free markets allow everyone to charge what they want for their graphene. Each company will have different price points based on several factors, but there is a significant potential for such a method to help drive down graphene costs across the board, as this kind of graphene production method can produce graphene in a much more cost-effective way than other graphene manufacturing methods.
Where All the Graphene Created from Waste Could be Used
There is a potential with this method to create a lot of graphene. There are many areas where graphene could be used and could have further environmental benefits.
The major one of which is within concrete and cement. The addition of graphene to these materials could reduce the industry’s CO2 emissions by around 2% (currently stands at around 8% of all global CO2 emissions). Such large volumes of graphene could be utilized so that 1/3 less concrete is needed for the same structural benefits, and the industry can create more environmentally friendly buildings.
Another big industry is the automotive sector, particularly within plastic composites. Every Ford car made from February 2020 onwards will feature graphene to decrease their weight and improve the structural properties of the vehicles. Once the usable life of the car has been finished, all the carbon-based components can be flashed (and re-flashed in the case of the graphene components) to create fresh graphene, creating a more circular production and recycling process.
Overall, the potential for a circular process where graphene-based materials could be made into fresh graphene without harsh chemicals offers an environmentally and cost-effective way of producing graphene. Moreover, graphene tends to take a long time to re-enter the CO2 cycle compared to other carbon materials, which is another way in which graphene can have a positive environmental impact.
One of the key points of this method is the ability to create graphene from any carbon-based waste. While the graphene created can be used to make other areas more environmentally friendly, the biggest environmental impact could be seen in the reduction of human waste, which is mounting up around the world. This is a key benefit, but it is a process that could help to bring down the cost of graphene, making it more accessible to more industries, who can then implement graphene and make their products more environmentally friendly. It is a circular and recyclable-type process that could bring benefits on many fronts. It will be interesting to see how Universal Matter scales the technology in the coming years.
References and Further Reading
Universal Matter. [Online] Available at: https://www.universalmatter.com/our-solution/
Karidis, A. (2020) Can Graphene from Waste Be a Breakthrough for Some Manufacturers? [Online] Waste 360. Available at: https://www.waste360.com/recycling/can-graphene-waste-be-breakthrough-some-manufacturers
Critchley, L. Inside the Industry: Dr. James M. Tour. [Online] NGA2D. Available at: https://www.nga2d.com/news/inside-the-industry-dr-james-m-tour/