This study is dedicated to investigating the performance of B2O3–Bi2O3–ZnO low-temperature glass-ceramics to immobilize iodine-loaded silver-coated silica-gel (AgIs). Various mass fractions of iodine (15, 20, 25, and 30 wt%) in AgIs were studied. The degree of amorphization and density increased with increasing sintering temperature for all immobilization samples, where, the sample with 20 wt% iodine in AgIs presented optimal immobilization results at 600 °C. The diffraction peak area of AgI was the lowest and the degree of amorphization was the highest (0.562) for the sample with 20 wt% iodine in silver-coated silica gel when it was sintered at 600 °C. SEM-EDS results showed that two approaches contributed to the immobilization of AgIs: the first one is that AgIs participates in the formation of the glass-ceramics phase, which makes iodine uniformly immobilized in the glass mesh; the second one is that the glass-ceramics phase physically encapsulates a small range of aggregated AgI. The results of TGA-DSC analysis showed that the samples had a high water content, which facilitated the lowering of the glass transition temperature of the samples and thus the curing of iodine. Most importantly, when the sintering temperature is below 600 °C, the evaporation of iodine is minimal to negligible. The leaching results showed that the samples were highly resistant to leaching of elemental iodine. This experiment verified the feasibility and efficiency of B2O3–Bi2O3–ZnO ternary glass-ceramics to immobilize iodine-loaded silver-coated silica-gel at low temperatures.
Yi Liu,Bingsheng Li,Xiaoyan Shu,Zhentao Zhang,Guilin Wei,Yi Liu,Shunzhang Chen,Yi Xie,Xirui Lu
To better deal with the radioactive iodine generated during the development of nuclear energy, B 2 O 3 , Bi 2 O 3 , ZnO, and SiO 2 were used to sinter borosilicate glass for the immobilization of iodine. The effect of B 2 O 3 on glass formation was discussed by changing the molar ratio of B 2 O 3 in the matrix. When B 2 O 3 content is 50 mol% and sintering temperature is 600 ℃, the amorphous degree of quaternary glass is the highest. The sintered body with the highest degree of amorphous was selected to study radioactive iodine. Then, the effects of different iodine loading concentrations for sintering borosilicate glass in terms of microstructure and phase change were discussed. With the increase in iodine content on silica-gel, the degree of amorphous of the specimens presented a decreasing trend, and there are obvious SiO 2 peaks. When the content was 20 wt. %-30 wt. %, a large number of new phases were generated. When the iodine content is 20 wt. %, in addition to the enrichment of Si and O elements, the elemental distribution for B, Bi, Zn, I, and Ag was even. TEM results also showed that there was a crystalline phase in the sinter.
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