Immobilization of silver-coated silica gel with varying iodine loading in silicate glass ceramics

•The sample with 50 mol% SiO2 shows the highest amorphous index (0.6).•Iodine wastes are immobilized in the matrix at 550 °C.•TEM results show the matrix is polycrystalline based glass ceramics.•The matrix sintered at 550 °C presents considerable chemical durability. In this study, we fabricated silicate glass ceramics using a mixture of oxides containing SiO2, B2O3, Bi2O3, and ZnO, to immobilize iodine adsorbed by silver-coated silica gels. The effects of SiO2 content on quaternary glass were explored by changing the molar ratio of SiO2 in the sintered matrix. The curing substrate with the highest amorphous index (0.6) was selected to simulate the immobilization of silver-coated silica gel loaded with 10, 20, 30, 40, and 50wt% iodine. Further, the effects of iodine concentration on the sintered matrix were analyzed based on phase structure and microstructure. The amorphous degree of sintered silicate matrix declines with increasing iodine loading in silver-coated silica gel. Transmission electron microscopy (TEM) results detected that a sample loaded with 20wt% iodine and sintered at 550 °C showed a polycrystalline glass-ceramic phase.