碳材料及其改性材料去除水中放射性核素研究

The application of carbon materials to remove radionuclides has received considerable attention in recent years, due to their large surface area, high adsorption capacity, great radiation, thermal, acid and alkali resistance. In combination of remarkable adsorption capacities of carbon materials with outstanding reactive properties and magnetism of magnetic nanoparticles, carbon materials can be modified and improved by the immobilization of magnetic nanoparticles, which can also be separated from the medium by a simple magnetic process. This work will choose activated carbon, carbon nanotube and graphene as substrates, and prepare a series of carbon materials immobilized magnetic nanoparticles (such as nanoscaled Fe0 and Fe3O4). The removal of radionuclides including uranium, cesium, strontium and cobalt by carbon materials will be investigated as well as the sorption kinetics/thermodynamics. The removal of radionuclides in the presence of different ions and multi-component competitive adsorption will be studied. The solid-liquid interface reaction mechanisms will be explored according to the results analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential method, physical property measurement system (PPMS), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), and so on. These results will provide the foundation for the development of novel sorbent material, and point toward an available method to mollify the severity of radionuclide contamination, thereby leading to effective measures for environmental remediation.

碳材料具有比表面积大、吸附能力强、抗辐射性能好、耐高温、耐酸碱等优点，近年来在放射性核素去除领域得到了广泛关注。将磁性纳米颗粒负载在碳材料表面，综合利用了磁性纳米颗粒独特的反应活性和磁性以及碳材料优越的吸附性能，可得到去除性能良好且易于分离回收的改性碳材料。本项目拟制备活性炭、碳纳米管和石墨烯三种碳材料，并对其进行改性，包括氧化纯化和负载纳米Fe0或Fe3O4；考察改性碳材料对放射性核素铀、铯、锶和钴的去除行为及吸附动力学/热力学过程；研究碳材料对共存离子和多组分竞争体系的吸附去除过程；并综合利用多种仪器分析技术（如XRD、SEM-EDX、Zeta电位、PPMS、XPS、EXAFS、FTIR等），在分子/原子等微观尺度上，多角度、多层次深入探索放射性核素在碳材料上的吸附过程以及固-液界面反应机制，为新型吸附剂的开发与应用提供有效的理论指导，也为放射性废水的妥善处理提供重要的科学依据。

本项目通过硼氢化钾还原氧化石墨烯（GO）和亚铁离子制备了纳米零价铁/石墨烯复合物（Fe0/GO），并将其用于吸附去除模拟核素Co(II)。综合利用X射线衍射（XRD）、扫描电镜（SEM）、高分辨透射电镜（HRTEM）、比表面积分析、zeta电位检测、磁滞回线等方法对Fe0/GO复合物进行了表征。研究了平衡时间、溶液pH值、材料用量、离子强度和反应温度对Fe0/GO吸附Co2+的影响，分析了吸附动力学和吸附热力学。根据Langmuir等温式，Fe0/GO复合物对Co(II)的吸附容量在10℃、20℃和30℃条件下分别为68.96、103.09和131.58 mg g-1。通过对吸附前后Fe0/GO复合物的红外光谱（FTIR）、X射线光电子能谱（XPS）和X射线吸收精细结构（EXAFS）分析，Co(II)在Fe0/GO复合物上的吸附主要是由于Co取代纳米Fe0上的Fe形成CoFe2O4以及Co2+和石墨烯表面羟基等官能团进行离子交换。本项目制备的Fe0/GO复合物去除Co(II)性能良好，并且具有磁性易于分离回收，在处理含放射性废水的实际应用中具有较大的前景。