RESUMEN
The immobilization of iodine waste suffers from serious iodine loss during heat treatment. Herein, we reported on the high iodine retention immobilization of simulated radioiodine-contaminated Bi0-SiO2 sorbent in B-Bi-Zn oxide glass using Bi2O3 as a stabilizer under a N2 atmosphere. The effects of the Bi2O3 content and sintering atmosphere on the iodine immobilization behaviors (iodine retention ratio, phase composition, microstructure, and chemical stability) were investigated. It was found that the decomposition of BiI3 was prevented by adding Bi2O3 and sintering in a N2 atmosphere. The iodine retention ratio in the obtained glass waste form was significantly enhanced with increasing Bi2O3 content and sintering in the N2 atmosphere due to the synergistic effect. The achieved record-high iodine retention (92.22 ± 2.6%) was much higher than that of conventional heat treatment route (18.01 ± 3.5%). The results demonstrated that iodine was effectively immobilized through the formation of stable BixOyI (Bi5O7I and BiOI). Furthermore, the obtained iodine waste form exhibited excellent compactness and chemical stability. Owing to its high iodine retention ratio, this route can be employed to effectively immobilize radioactive iodine.
RESUMEN
Manganese dioxide-loaded mesoporous SBA-15 silica (MnO2/SBA-15) composites with short pore length were aprepared for the first time by simply immersing SBA-15 into a KMnO4 and MnCl2 mixed solution. Adsorption of Sr2+ from aqueous solution by using the MnO2/SBA-15 was investigated by varying the pH, contact time, initial Sr2+ concentration, MnO2 content and temperature. The adsorption process was rapid during the first 40 min and reached equilibrium in 120 min. The Sr2+ adsorption capacity increased with increasing pH, MnO2 content and temperature, and the adsorption capacity of SBA-15 was significantly improved by the loading of MnO2. Moreover, the experimental adsorption data were analyzed using different equilibrium isotherm, kinetic and thermodynamic models. The results showed that the isotherm data were well-described by the Langmuir model. The maximum Sr2+ adsorption capacity was determined to be 75.1 mg g-1 at 283 K based on the Langmuir model. The analyzed kinetic data indicated that the Sr2+ adsorption process was well fitted by the pseudo-second order model. Furthermore, the thermodynamic parameters of adsorption were also determined from the equilibrium constant values obtained at different temperatures. The results suggested that the adsorption process was spontaneous and endothermic, and the overall mechanism of Sr2+ adsorption was a combination of physical and chemical processes.
