Water is the universal solvent on the planet, and without it, minerals and nutrients can’t be transported. Life would cease to exist. This property of water, though, means it also transports and disperses toxins just as easily, including radioactive materials.
Cleanup around nuclear sites, such as the recent disaster at the Fukushima Daiichi nuclear power plant in Japan, is difficult and costly. Radioactive materials are often brought up unintentionally at hydraulic fracturing, or “fracking,” sites and cannot simply be dumped back into the ground, where it can contaminate groundwater supplies. “Hot” contaminated water has to be shipped at great expense to safe storage areas.
Current methods of radioactive cleanup, including bentonite clay and activated carbon, are somewhat effective, but are sometimes too slow to prevent the escape of radioactive materials into the environment. A faster method could greatly increase the effectiveness of emergency response teams in radioactive areas.
The nanomaterial graphene oxide, molecule-thick carbon sheets, have an immense surface area, can be produced cheaply, and disperse quickly in water. Graphene oxide bonds almost instantly with contaminants in water down to the ionic level, causing them to clump together.
In tests, graphene oxide bonded within minutes to contaminants in water, including uranium, plutonium and other radioactive isotopes. After clumping, the graphene could possibly be burned off, leaving pure radioactive materials that can be reused or disposed of.
The key here is the speed at which graphene oxide is effective. “Graphene oxide introduced to simulated wastes coagulated within minutes, quickly clumping the worst toxins. The high retention properties are not surprising to us, but what is astonishing is the very fast kinetics of sorption, which is key,” said chemist Stepan Kalmykov.
Minutes instead of days could mean the difference between a site contaminated for decades or mere days. Fracking sites could benefit being able to skim off radioactive graphene oxide clumps on site and return clean water back to the environment.