Mo在岩石和土壤介质中的吸附-解吸特性

    Adsorption and Desorption of Molybdenum on Rock and Soil Media

    • 摘要: 放射性99Mo释放到环境中可能会在辐射安全和环境安全方面带来不利的影响,研究钼(Mo)在环境介质中的迁移行为对核工业的健康发展和环境保护具有重要意义。目前极少通过研究特定区域内Mo(Ⅵ)的吸附情况来关注辐射安全问题。本工作以中国拟建的放射性药物研发装置附近区域为研究对象,开展了Mo在该区域代表性介质(粉质黏土、粗砂、强风化粉砂质页岩、中风化粉砂质页岩、强风化炭质页岩和中风化炭质页岩)中的吸附-解吸实验。结果表明,Mo在6种岩土介质中的吸附过程符合准一级和准二级动力学模型。Langmuir模型和Freundlich模型均能较好地描述Mo在岩土介质中的等温吸附-解吸过程。Mo在岩土介质中的吸附-解吸分配系数值呈现出强风化炭质页岩>中风化炭质页岩>粉质黏土>强风化粉砂质页岩>中风化粉砂质页岩>粗砂的变化趋势。分配系数值与岩土介质的有机质含量呈极强正相关。

       

      Abstract: The release of radioactive 99Mo into the environment may lead to adverse effects on radiation safety and environmental security. Studying the migration behavior of molybdenum in environmental media is of great importance for the healthy development of the nuclear industry and environmental protection. To the best of our knowledge, rare studies focused on radiation safety by studying the molybdenum adsorption in aspecific area. In this study, rock, soil, and groundwater samples were collected from the vicinity of a proposed radioactive pharmaceutical research facility in China. Adsorption-desorption experiments of molybdenum in environmental media were conducted to investigate the adsorption kinetics and adsorption-desorption isotherms of molybdenum in silty clay, coarse sand, strongly weathered silty shale, moderately weathered silty shale, strongly weathered carbonaceous shale, and moderately weathered carbonaceous shale. The mineral compositions of the six kinds of rock and soil samples are similar, with quartz, illite, and chlorite as the primary components and their main chemical components of the six rock-soil samples are SiO2, Al2O3, Fe2O3, MgO, K2O, and FeO. The cation exchange capacity of the six kinds of rock-soil samples ranges from 1.92 to 20.20 cmol+/kg and the organic matter content ranges from 9.5 to 60.0 g/kg. The adsorption process of molybdenum in the six types of rock-soil media conforms to pseudo-first-order and pseudo-second-order kinetic models. Both the Langmuir and Freundlich models effectively describe the adsorption-desorption process of molybdenum in rock-soil media. The adsorption Kd values of molybdenum in silty clay, coarse sand, strongly weathered silty shale, moderately weathered silty shale, strongly weathered carbonaceous shale, and moderately weathered carbonaceous shale are 0.064, 0.021, 0.042, 0.028, 0.290 and 0.209 L/g, respectively. The desorption K'_\mathrmd values of molybdenum in these six rock-soil samples are 0.076, 0.027, 0.049, 0.035, 0.410 and 0.278 L/g, respectively. The desorption K'_\mathrmd values are 1.17-1.41 times the adsorption distribution coefficient values. The distribution coefficient values exhibit a trend of strongly weathered carbonaceous shale>moderately weathered carbonaceous shale>silty clay>strongly weathered silty shale>moderately weathered silty shale>coarse sand. The organic matter content of rock and soil media is the most critical factor influencing the distribution coefficient values. A linear relationship exists between the organic matter content of rock and soil media and the distribution coefficient. Based on the organic matter content, the distribution coefficient of Mo in rock and soil media can be predicted rapidly. This research provides fundamental data on the migration of molybdenum in rock-soil media and offers a scientific basis for establishing relevant safety standards.

       

    /

    返回文章
    返回