Effective decontamination of (TcO4-)-Tc-99/ReO4- from Hanford low-activity waste by functionalized graphene oxide-chitosan sponges

Treatment and recycling of radioactive waste are major challenges for the nuclear energy sector. Pertechnetate anions, (TcO4-)-Tc-99, occur in nuclear waste and are formed mainly during nuclear fission. (TcO4-)-Tc-99 is a very hazardous contaminant due to its long half-life and high solubility and mobility in water. The effective capture of Tc-99 contamination at legacy nuclear sites remains a serious and unsolved environmental issue. In this work, (TcO4-)-Tc-99/ReO4- was adsorbed by compressible graphene-chitosan sponges with grafted tertiary amine groups. Moreover, the hydrophobic branched chains strongly reduced the interference of competitive anions during adsorption. Results show that (TcO4-)-Tc-99/ReO4- can be effectively removed even under highly acidic conditions and in the presence of competing anions. More than 98% of (TcO4-)-Tc-99/ReO4- was removed using simulated nuclear wastes.