Research collaboration between Russian and US chemists has discovered a new use for graphene oxide flakes—the clean-up of radionuclide contaminated water. Radioactive elements are harmful even in small concentrations, making any remediation of radioactive materials in water a slow process simply for the facts that very few radioactive particles may come in contact with reactants that have relatively little surface area for reaction. Graphene Oxide flakes inherently have large surface areas and are readily soluble in liquids. In addition to their large relative surface area, these nanothin particles have very fast sorption kinetics. These nanoflakes react with radioactive material including rare earth elements, plutonium, and uranium in liquids, attracting them to their surface and creating a precipitate in the liquid that is easily filtered.
The graphene oxide flakes are easily manufactured and display better sorption kinetics than bentonite clays or activated carbon filters used in conventional radioactive contaminated water cleanup. While the graphene does not eliminate the radioactive wastes, it concentrates the waste into a solid making it much easier to deal with. Graphene oxide is combustible, burning rapidly. This property allows the concentrated radioactive materials to be concentrated into dry solids that can then be repurposed and recycled for fuel or can be mined for their rare earth minerals in the case of water contaminated with radioactive actinides or lanthanides.
Graphene Oxide is manufactured through a simple chemical reduction-oxidation (RedOx) method that requires mixing crystalline graphite with sodium nitrate, sulfuric acid, and potassium permanganate. The formation of the thin films to create flakes is done by either chemical reduction with hydrazine, or bacterial synthesis; the latter being a “green” method free of additional chemicals.
- . Another tiny miracle: Graphene oxide soaks up radioactive waste. [Internet]. 2013 . Available from: http://news.rice.edu/2013/01/08/another-tiny-miracle-graphene-oxide-soaks-up-radioactive-waste/
- . Graphene oxide for effective radionuclide removal. Physical Chemistry Chemical Physics. 2013 ;15(7):2321.
- . Graphene oxide 'removes radionuclides from water'. [Internet]. 2013 . Available from: http://www.theengineer.co.uk/sectors/energy-and-environment/news/graphene-oxide-removes-radionuclides-from-water/1015157.article[
- . Graphene Oxide – Properties and Practical Applications. [Internet]. 2011 . Available from: http://www.azonano.com/article.aspx?ArticleID=2934#3
This technology enhances the speed and sorption efficiency of conventional methods of decontaminating radioactive fluids.
There are many potential benefits for the radionuclide sorption properties of graphene oxide flakes. Graphene oxide flakes could be used in the cleanup of radioactive water from nuclear accidents or during the decommissioning stage of nuclear energy production. Graphene oxide could be used in water treatment to reduce radioactive ionized mineral content in water from anthropogenic or natural sources. Graphene oxide flakes also offer promise for significant waste and cost reduction in oil and gas hydrofracturing; a process that often results in radioactive water contamination once the fracking fluids are extracted from the well. Additionally, graphene Oxide offers potential benefits in recovery of rare earth minerals from low concentration solutions. These benefits may help make nuclear energy safer, cost effectively reduce the risks of low carbon energy sources like natural gas, and reduce the resource and energy impacts in mining operations.
This technology is still in the early scientific phase so few studies have been conducted on the risks associated with burning graphene. Additionally, the secondary risks of introducing large amounts of graphene into fresh water sources during hydraulic fracturing and mining have not been studied. For these reasons, the risks associated with this application of graphene oxide are unknown until further research is conducted.