以硅胶为载体,采用水热浸渍法制备银修饰硅胶复合材料,对富碘后的复合材料进行低温玻璃固化处理,以期实现对气态放射性碘的长期安全处置。通过扫描电子显微镜和X射线衍射仪对复合材料的形貌和结构进行表征,考察了浸渍反应温度对银负载量、吸附时间和碘质量浓度对碘吸附量的影响,并对吸附动力学曲线和吸附等温线进行了拟合。结果表明:硝酸银负载在硅胶表面,银负载量达到17.8%;30min内复合材料对气体碘的吸附可达到平衡,吸附行为符合准二级动力学模型,为化学吸附;Langmuir等温吸附模型更适合描述复合材料对气态碘的吸附过程,复合材料吸附碘的过程为单层吸附行为,复合材料对碘的理论最大吸附量为169.5mg/g。固化结果表明,玻璃固化体主要以碘化银(AgI)和碘七氧化五铋(Bi5O7I)形式封存碘,碘元素浸出率为1.436×10-6g/(m2·day)。
In order to achieve the long-term safe disposal of gaseous radioactive iodine,silver-modified silica gel composites were prepared by hydrothermal impregnation method using silica gel as a carrier,and the iodine-enriched composites were treated with low temperature glass solidification.The morphology and structure of the composites were characterized by scanning electron microscopy and X-ray diffraction.The effects of impregnation reaction temperature on silver loading,adsorption time,and iodine mass concentration on iodine adsorption were investigated.The adsorption kinetic curves and adsorption isotherms were fitted.The results showed that silver nitrate was loaded on the silica gel surface,and the silver loading reached 17.8%.The adsorption of gaseous iodine by the composites within 30min could reach equilibrium,and the adsorption behavior conformed to the quasi-second-order kinetic model,which was chemisorption.The Langmuir isothermal adsorption model was more suitable to describe the isothermal adsorption process of gaseous iodine by composites,suggesting a monolayer adsorption behavior.The theoretical maximum adsorption capacity of iodine by composites was 169.5mg/g.The solidification results indicated that the glass-cured body sequestered iodine mainly in the forms of silver iodide (AgI) and iodine pentabismuth heptoxide (Bi5O7I),and the leaching rate of iodine was 1.436×10-6g/(m2·day).
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基金资助
西南科技大学校级科研项目(22zh0036)
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