A new process introduced by the Rice University researchers can turn bulk quantities of just about any carbon source into valuable graphene flakes. The process is quick and cheap. This “flash graphene” technique can convert a ton of coal, food waste or plastic into graphene for a fraction of the cost used by other bulk graphene-producing methods.
This is a big deal. The world throws out 30% to 40% of all food, because it goes bad, and plastic waste is of worldwide concern.
Any solid carbon-based matter, including mixed plastic waste and rubber tires, can be turned into graphene using this new process.
Graphene is a wonder material with amazing, unbelievable properties. For example, it is about 100 times stronger than the strongest steel. Yet its density is dramatically lower than any steel.
It conducts heat and electricity very efficiently and is nearly transparent.
These properties of Graphene encourage many researchers to develop a lot of amazing things in various fields.
So, there is a huge demand for the production of Graphene.
Most bulk-scale graphene is produced by a top-down approach, i-e exfoliating graphite which we found in pencil. But this process often requires large amounts of solvent with high-energy mixing, shearing, sonication or electrochemical treatment. Although chemical oxidation of graphite to graphene oxide promotes exfoliation, it requires harsh oxidants and leaves the graphene with a defective perforated structure after the subsequent reduction step.
And, Bottom-up synthesis of high-quality graphene is often restricted to ultrasmall amounts if performed by chemical vapour deposition or advanced synthetic organic methods, or it provides a defect-ridden structure if carried out in bulk solution.
So, the finding of this new process will be significant as it uses no furnace and no solvents or reactive gases and no purification steps are necessary. It just uses Flash Joule heating approach. i-e passing electric current for heating the material.
As reported in Nature, flash graphene is made in 10 milliseconds by heating carbon-containing materials to 3,000 Kelvin (about 5,000 degrees Fahrenheit). The source material can be nearly anything with carbon content. Food waste, plastic waste, petroleum coke, coal, wood clippings and biochar are prime candidates.
The electric energy cost for this Flash Graphene synthesis is only about 7.2 kilojoules per gram, which could render Flash Graphene suitable for use in bulk composites of plastic, metals, plywood, concrete and other building materials.
With the present commercial price of graphene being $67,000 to $200,000 per ton, the prospects for this process look superb.
A concentration of as little as 0.1% of flash graphene in the cement used to bind concrete could lessen its massive environmental impact by a third. Production of cement reportedly emits as much as 8% of human-made carbon dioxide every year.
By strengthening concrete with graphene, we could use less concrete for building, and it would cost less to manufacture and less to transport.
Bulk composites of graphene with plastic, metals, plywood, concrete and other building materials would be a major market for flash graphene.
In the past, graphene has been too expensive to use in these applications. The flash process will greatly lessen the price while it helps us better manage waste.
The flash process happens in a custom-designed reactor that heats material quickly and emits all noncarbon elements as gas. When this process is industrialized, elements like oxygen and nitrogen that exit the flash reactor can all be trapped as small molecules because they have value
And, this flash process produces very little excess heat, channeling almost all of its energy into the target.
All the excess energy comes out as light, in a very bright flash, and because there aren’t any solvents, it’s a super clean process.
Even better, the process produces “turbostratic” graphene, with misaligned layers that are easy to separate. Turbostratic graphene is much easier to work with because the adhesion between layers is much lower. They just come apart in solution or upon blending in composites.
News Source: Rice University
