Effective decontamination of 99TcO4−/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, 99TcO4−, occur in nuclear waste and are formed mainly during nuclear fission. 99TcO4− is a very hazardous contaminant due to its long half-life and high solubility and mobility in water. The effective capture of 99Tc contamination at legacy nuclear sites remains a serious and unsolved environmental issue. In this work, 99TcO4−/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 99TcO4−/ReO4− can be effectively removed even under highly acidic conditions and in the presence of competing anions. More than 98% of 99TcO4−/ReO4− was removed using simulated nuclear wastes.