Role of amorphous silica gel in B2O3-Bi2O3-ZnO-SiO2 to immobilize iodine waste

The treatment of radioactive iodine waste is particularly difficult because of its volatilization issues. In this study, amorphous silica gel was used to gradually replace crystalline SiO 2 in B 2 O 3 -Bi 2 O 3 -ZnO-SiO 2 based materials aimed to investigate the effects on iodine waste immobilization. Samples with different silica gel replacements (0, 20, 40, 60, 80, and 100%) were characterized by XRD, FT-IR, and SEM-EDS. The results showed that silica gel had a benefit in the immobilization of iodine waste at low-sintering temperatures (500, 550, and 600 °C). At 550 °C, AgI was immobilized in the pure glassy matrix and elements (Ag and I) distributed uniformly on the matrix surface. FT-IR analysis presented the tetrahedral SiO 4 units in the sintered samples that were mainly in the form of sheets. Our work revealed the potential application of silica gel in the field of iodine waste immobilization.