Bismuth Coordinates with Iodine Atoms to Form Chemical Bonds for Existing Stabilization in Boron Glass

Abstract

Stabilizing radioactive iodine in boron glass for disposal was the ultimate goal of this study. In this study, bismuth was used near a monument. Thermogravimetric analysis showed that bismuth could remarkably stabilize iodine atoms in boron glass (only 3.74% of the mass was lost at 850 °C). Scanning electron microscopy–energy dispersive spectrometry images showed that most of the AgI was uniformly immobilized in the glass network. X-ray photoelectron spectrometry and NMR results confirmed the change in the coordination number of boron in the samples. The density functional theory calculation helped to understand the reason for the stable presence of iodine in boron glass. Iodine atoms were difficult to bond directly with boron atoms but tended to bond with bismuth atoms. From the spatial distribution of the structural molecular orbitals, it was observed that the bismuth atom releases electrons when stimulated, and the iodine atom needs to gain an electron to reach stability. At a low treatment temperature of 550 °C, the maximum density of the immobilized sample containing bismuth is 2.42 g·cm–3, and its iodine leaching rate at day 7 can be as low as 3.77 × 10–6 g·m–2·d–1. This study provides a way to improve the properties of boron glass microscopically in the future.

High Retention Immobilization of Iodine in B–Bi–Zn Oxide Glass Using Bi2O3 as a Stabilizer under a N2 Atmosphere

“…The normalized leaching rates of immobilized I in various matrices are summarized in Table S2. As shown in Table S2, the leaching rate of I in this work was higher than that of the AgI immobilized in Bi−P−Zn glass, 14 Boron glass, 37 B−Bi−Zn−Si glass 52 and W(Mo or V)−Ag−Te glass, 53 which may be attributed to the fact that AgI was more stable than Bi x O y I. However, it was comparable with the immobilization of Bi x O y I in B−Bi−Zn glass 21 and iodate in glass−zeolite−4A 54 and lower than that of the immobilization of iodate in Pb−B−Zn glass 55 and Cs 3 Bi 2 I 9 in perovskite−silica.…”

“…Furthermore, this value was much higher than that of immobilization of BiI 3 into B− Bi−Zn glass (34%) 21 and iodate into B−Si−Na glass (47%). 26 It was lower than that of immobilization of AgI into boron glass (96.26%), 37 but this is a record high in the BiI 3 form of waste immobilization. The iodine retention ratio increased with the increase of Bi 2 O 3 content, which may be due to the fact that the reaction between BiI 3 with Bi 2 O 3 was enhanced, so that the less BiI 3 was decomposed during the sintering process.…”

Research on the Effect of Silica Gel in the Formation of Glass Solidified Body Containing Radioactive Iodine: Structure and Properties

“…However, from the perspective of the relative intensity of the peak, a part of the [BO 3 ] groups in the material changed to [BO 4 ]. The [BO 4 ] groups make the glass network structure more stable than the [BO 3 ] groups . From the above phenomenon, it can be seen that the addition of silica gel changed the structure of the material and improved the degree of polymerization of the material structure.…”

“…The [BO 4 ] groups make the glass network structure more stable than the [BO 3 ] groups. 32 From the above phenomenon, it can be seen that the addition of silica gel changed the structure of the material and improved the degree of polymerization of the material structure. As shown in Figure 3b, for the iodinecontaining B−Bi−Zn−silica gel material, the changes in the related groups were not obvious and were still consistent with the B−Bi−Zn−silica gel material.…”

Review of recent developments in iodine wasteform production

“…To control the properties of a boron glass ceramic, ZnO and Bi 2 O 3 have been added to aid in formation of separate BO 4 and ZnO 4 glass units along with the stabilized Ag. Bi 2 O 3 can form BiO n (n = 3 or 6), which can combine with B 2 O 3 to favor formation of BO 4 units which increase glass stability (Litwinek-Rozbicka et al, 2021;Feng et al, 2022;Wen et al, 2022). ZnO reduces the glass transition temperature and increases the density of the glass (Kim et al, 2009).…”