活性多孔氮化硼吸附-载带同时去除多种放射性核素的机制研究

A large amount of radioactive wastewater may be produced with the rapid development of nuclear industry or nuclear accidents. The persistent radioactivity and biological toxicity of radioactive wastewater cause serious harm to the ecological environment and human health. The treatment of radioactive wastewater with adsorption method possesses the advantages of without adding chemical agents, lower energy consumption and better effect. However, lower adsorption capacity and difficult to remove multiple species simultaneously are the problems to be solved. Active porous boron nitride, which is a new kind of efficient adsorbent, with a larger specific surface area, and B-N polar covalent bonds could adsorb cations through electrostatic attraction.. The simultaneous removal of multiple nuclide from simulated radioactive wastewater by active porous boron nitride adsorption-carry effect is proposed in this project. The activated porous boron nitride with high adsorption capacity is prepared by a two-step in situ activation method. The rules between the control of preparation conditions and the adsorption performance will be proven. The adsorption effect of different nuclide by activated porous boron nitride will be investigated. The relationship between the structural characteristics of active porous boron nitride and the removal mechanisms of different nuclide will be studied. A method with the combine of the analysis of adsorption data and the micro analytical of molecular structure is used to thoroughly study of adsorption mechanisms. The simultaneous removal of 4-6 kinds of nuclide from radioactive wastewater by carrying mechanism through changing the initial concentration of stable isotopes will be studied to improve the decontamination factor. This project will provide a new idea for the development of radioactive wastewater treatment technology with a high efficiency and low consumption.

核电事业的高速发展以及核事故的发生会产生大量的放射性废水，其持续的放射性和生物毒性对生态环境和人类健康造成严重的危害。吸附法处理放射性废水，不需投加化学药剂且能耗低、效果好，但亟待解决吸附量低、难以同时去除多种核素的问题。多孔氮化硼比表面积大，含有B-N极性共价键，可通过静电引力吸附阳离子，是一种新型高效的吸附剂。.本项目提出利用活性多孔氮化硼吸附-载带同时去除模拟放射性废水中的多种核素。采用两步法原位活化制备出具有高吸附性能的活性多孔氮化硼，探明制备条件的控制与产物吸附性能之间的规律；考察废水的性质对核素吸附效果的影响，研究活性多孔氮化硼的结构特征与不同核素去除机制的关系；采用吸附数据宏观分析与分子结构微观解析相结合的方法深入研究吸附机理；通过改变稳定同位素的初始浓度，利用载带机制同时去除放射性废水中4-6种核素，提高去污因数。本项目的研究可为开发高效低耗的放射性废水处理技术提供新思路。

含有放射性核素的废液进入环境后，会对生态环境和人类健康造成长期严重的危害。妥善处理放射性废水是我国乃至全球面临的重要课题。本项目以制备出可适用于吸附与膜分离联用的活性多孔氮化硼为目标，通过改变活化剂的用量及活化温度获得了具有高比表面积、丰富孔径分布和表面官能团的活性多孔氮化硼。通过对前驱体干燥温度的控制得到微米级的吸附剂，可与微滤膜过滤进行良好的匹配。系统研究了活性多孔氮化硼对模拟放射核素Cd2+、Cu2+、Ni2+和Mn2+的吸附性能，获得了吸附量、吸附等温线、吸附动力学、最佳的pH应用范围等基本吸附数据，考察了不同浓度的Ca2+、Mg2+、K+、Na+等竞争离子的存在对目标核素去除的影响，得出了活性多孔氮化硼对不同核素以及非放射性竞争离子的吸附规律，提出了离子间存在的交互作用影响吸附规律。采用了实验数据的宏观分析与分子结构的微观解析相结合的方法研究吸附机理。揭示了活性多孔氮化硼上B-N-B、B-N-O、B-OH等不同化学键与多种核素之间的相互作用机制。开发出膜吸附反应器，利用活性多孔氮化硼对废水中高浓度稳定同位素的高效吸附性能，载带去除废水中低浓度的放射性核素，再利用微滤膜进行固液分离。考察了反应器内活性多孔氮化硼的颗粒尺寸分布、曝气量和膜通量等参数对不同核素的去污因数和膜污染的影响，实现了同时去除多种放射性核素。