放射性核素铯污染土壤提取-吸附处理技术应用基础研究

With the rapid development of nuclear power plants in china, it is urgent to develop practical remediation technologies because of the lack of remediation technologies reserves for the effective remediation of cesium contaminated soil caused by nuclear accident. In this project, we intend to study the effect of extraction conditions from cesium contaminated soil, and then optimize the optimal extraction conditions and process parameters. The ammonium phosphomolybdate and functional magnetic materials are used as raw materials, polyvinyl alcohol is used as the carrier for the preparation of porous magnetic adsorbent. The morphology, microstructure, physical and chemical properties of the adsorbent are characterized by using the scanning electron microscope(SEM), transmission electron microscopy (TEM), X-ray crystal diffraction (XRD),surface area and pore size analyzer and X-ray photoelectron spectroscopy (XPS). The effects of preparation methods and conditions on the structure and properties of the adsorbent are studied, and its preparation process is also optimized. The experiment and differential modeling method are used to study the mechanism of mass transfer between adsorbent, cesium contaminated soil and extractant, and then obtain the kinetic parameters of cesium between different media. The adsorption behavior, mechanism and process of cesium by adsorbent would be studied by advanced spectroscopy, and the recycling of adsorbent would be researched. The extraction-adsorption treatment system of cesium contaminated soil would be established. The response surface method is used to optimize the operating parameters of different sections of the treatment system, and then the optimal operation scheme under different conditions would also be obtained. The results of this project will provide more options for the urgent remediation technology of radioactive contaminated soil.

我国正处在核电站发展高峰期，目前对于核事故导致的放射性污染土壤修复缺乏技术储备，开发实用修复技术迫在眉睫。本项目拟研究提取条件对铯污染土壤中铯的影响作用规律，优化最佳提取条件和工艺参数；以磷钼酸铵和功能化磁性物质为原料，以聚乙烯醇为载体制备多孔磁性材料；运用扫描电镜、透射电镜、X射线晶体衍射、比表面孔径分析仪和X射线光电子能谱仪等手段对吸附材料进行表征，研究制备方法和条件对吸附材料结构和性能影响，优化制备工艺。采用实验和微分建模的方法研究吸附剂-受铯污染土壤-提取剂之间的传质运移规律，得到铯在不同介质之间的动力学参数。研究吸附剂对铯的吸附行为与过程，采用先进的谱学手段研究其吸附机理，并探索吸附剂的循环再利用方案。建立放射性核素铯污染土壤提取-吸附处理系统，采用响应面法优化处理系统不同工段的运行参数，获得不同条件下的最优运行方案。本项目研究结果将为放射性污染土壤修复技术的应急储备提供参考。

我国正处在核电站发展高峰期，目前对于核事故导致的放射性污染土壤修复缺乏技术储备，开发实用修复技术迫在眉睫。本项目筛选得到了对土壤中的铯进行高效提取的药剂，优化了最佳提取条件和工艺参数；以蒙脱石为基底制备出铵根改性蒙脱石磁性海藻酸钠微球（MCCA），其对铯的最大吸附容量为86.46mg/g；以磷钼酸铵为主要活性成分，制备出两种新型磁性复合多孔吸附材料，分别是磷钼酸铵交联海藻酸钙磁性微球（ACCA），其对铯的最大吸附容量为27.68mg/g，磷钼酸铵@海藻酸钠/聚乙烯醇磁性微球（AMP@CA/PVA），其对铯的最大吸附容量为93.03mg/g；对可回收磁性复合材料进行了再生效果评价，得到了吸附剂的循环再利用方案。以筛选得到的提取药剂以及制备的磁性复合多孔材料为基础，建立了放射性核素铯污染土壤一步提取-吸附处理系统，并采用响应面法优化了工艺的运行参数，获得不同条件下的最优运行方案；基于密度泛函理论，通过分析和研究吸附剂不同吸附位点、吸附能和电子转移等主要性质，在分子和原子水平上分析了铯的吸附机理；运用SEM，XPS，XRD，FT-IR等手段考察磁性复合多孔材料的结构特征，在宏观角度佐证其吸附机理，揭示了铯在不同介质间的传输运移规律。本项目研究结果将为放射性污染土壤修复技术的应急储备提供参考。