Researchers at Rice University have optimized a process to convert waste rubber from old tires into graphene. These graphene can be used to strengthen concrete. The environmental benefits of adding graphene to concrete are obvious, says research chemist James Toure. Concrete is one of the most productive materials in the world, and the carbon dioxide emissions from the production of concrete account for as much as 9% of the world`s carbon dioxide emissions.
If we can use less concrete in roads, buildings and bridges, we can eliminate part of the carbon dioxide from the beginning. Portland cement has used recycled tire waste as a component, but graphene has been shown to strengthen cement-based materials, including concrete, at the molecular level.
Most of the 800 million tires discarded each year are burned for fuel or ground for other purposes, and 16% of old tires are eventually landfilled. If even a small fraction of the tires in these landfills can be recycled into graphene, millions of tires can no longer enter the landfill. Tour and colleagues published the “shock” process used in 2020 to expose food waste, plastics, and other carbon sources to shocks and remove all substances except carbon atoms from the sample, thereby converting it.
These atoms recombine into valuable turbine graphene, whose misaligned layers dissolve more easily than graphene produced by graphite stripping, thus making graphene easier to use in composites. The researchers stated that rubber is more difficult to convert to graphene than food or plastic, but the process was optimized using commercial pyrolysis waste rubber from tires.
A mixture of tire-derived carbon black, rubber tire debris, and commercial carbon black can be converted into graphene. Since this graphene is soluble, it is easy to add to cement to make more environmentally friendly concrete. In the test, approximately 70% of tire-derived carbon black could be converted to graphene.
About graphene (source: matexcel.com)
Graphene is an atomic-scale honeycomb lattice made of carbon atoms. It is the world`s first 2D material and is one million times smaller than the diameter of a single human hair. However, it is many times stronger than steel, yet incredibly lightweight and flexible. It is electrically and thermally conductive but also transparent. As a single layer graphite, graphene has raised great interest due to its potential applications in different fields of material science for developing nanocomposites, sensors, supercapacitors, hydrogen storage, photonics and optoelectronic devices.
The oxidation of graphite produces graphite oxide (GO) which has hydrophilic functional groups (-OH, epoxide, -COOH). Those groups promote the intercalation of water molecules into the gallery and the graphene sheets can be easily detached from each other by sonication, thus producing highly dispersible GO sheets in aqueous medium. These exfoliated GO sheets are usually used for different applications or are further functionalized to use for targeted applications. For example, the GO is electrically insulating but becomes conducting when it is reduced to produce reduced graphene oxide (rGO) by sodium borohydride or hydrazine hydrate.
About the author
Collected by Matexcel that provides a wide range of graphene products for its customers to help improve the quality of life for many across the globe including: Carbon nanotubes, CVD graphene, fullerene, functionalized graphene, functionalized graphene oxide, graphene aerogel, graphene composite, graphene dispersion/slurry, graphene foam, graphene foil, graphene nanopowder, graphene oxide, graphene sheet, and reduced graphene oxide.
Visit matexce.com to know more.
