Research collaboration between Russian and US chemists has discovered a new use for graphene oxide flakes—the clean-up of radionuclide contaminatedwater. 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.
Figure 1: Left: Graphene oxide flakes dissolved in water. Right: Graphene oxide flakes clumping with radioactive materials in solution (Source: Romanchuk, Anna Yu 2013)