Radioactive Waste 211 - Oxidatively Modified Carbon May Be Effective And Economical To Decontaminate Water At Fukushima
The Fukushima nuclear disaster occurred in March of 2011 in Japan, almost 6 years ago. Since then billions of gallons of contaminated water have flowed into the Pacific Ocean from the destroyed power plant. Millions of gallons more are stored onsite in leaking tanks. It is too "hot" to dump into the ocean and, if left alone, it will seep into and contaminate the soil under the tank farm. Now there is hope that there may be a method to economically remove the contamination from the water in the tanks.
Scientists from Rice University in Texas and Kazan University in Russia are working on a method for removing the radioactive isotopes of cesium and strontium in the contaminated water. They have identified a cheap material called oxidatively modified carbon (OMC) which may be used in filters to remove the isotopes which would make the water safe enough to dump into the ocean.
Carbon is a common element used in many water filtration systems. However, the type of carbon used in common filters does not do a good job of removing radioactive materials from water. The team of scientists had previously found that carbon in the form of graphene oxide was good at removing strontium but not as good as removing the cesium. In addition, graphene oxide is expensive to manufacture.
The team then began to explore the possibility of using OMC as a filter material. OMC is one tenth the cost of graphene oxide and much easier to use in standard filtration systems. OMC can be made from a commercial carbon coke source called C-seal-F which is a common additive for fracking oil fluids. OMC can also be made from “shungite” which is a common mineral in parts of Russia. The C-seal-F or shungite is treated with acids which create surfaces rich in oxygen on the carbon particles which are between ten and eighty microns wide. When brought into contact with OMC, heavy metal ions attach to those surfaces in a process called adhesion.
When water laced with cesium, strontium, and other heavy metals was run through filters made with OMC from C-seal-F, about eighty percent of the cesium and seventy percent of the strontium was removed. Running the same experiment with OMC made from shungite resulted in removal of about seventy percent of the cesium and fifty percent of the strontium. The efficiency of the OMC filters with respect to cesium is especially promising because cesium is one of the most difficult isotopes to remove from contaminated water.
Previous types of sorbent materials used to filter radioactive materials from water have to be stored as radioactive waste once they are used. OMC can be burned in a nuclear incinerator producing a small amount of radioactive ash.
These experiments were just a proof of the basic concept and were run without the radioactive isotopes of cesium and strontium. Research still needs to be done to determine whether or not the radioactive isotope will have any influence on the percentage of removal as well as the integrity and lifespan of the filter material.
Shungite:
