Study of Treatment of Radioactive Waste using Anion-Exchange Paper Membrane

放射性碘被广泛用于原子能、医疗、医学诊断和生物实验。然而，由于放射性碘很容易被人体吸收，并且对健康有很大的危害，世界各国对含放射性碘的放射性废物的使用和处置都有严格的法律规定。在本研究中，我们开发了利用阴离子交换纸膜浓缩水中以阴离子形式存在的放射性碘的方法如下：(1)研制了四种具有强碱性阴离子交换中心的阴离子交换纸膜，并将其分散在高密度的膜中。(2)基于非平衡热力学，利用所制备的阴离子交换膜来评价浓缩池系统中的离子迁移。特别是通过静电效应表示离子溶液/膜分布的导电膜透过率和表示膜相离子迁移速度的扩散膜透过率。(3)阴离子交换纸膜中电子中和分子对放射性碘传输的共存效应评价。(4)电渗析和扩散渗析分离放射性碘与放射性废物的比较。该纸膜对碘具有较高的渗透选择性。在浓差电池体系中，I-125对氯-36的导电膜渗透率达到6.2。

Radioactive iodine is extensively used in an atomic power, medical treatment, medical diagnosis, and biological experiments. However, the use and disposal of radioactive waste containing radioactive iodine are strictly regulated by laws in the world because radioactive iodine is readily absorbed into body and represents a significant health hazard.In the present study, we developed the concentration method of radioactive iodine that exists as an anion in water using anion-exchange paper membrane as below :(1)Development of four kinds of anion-exchange paper membranes that have strong base anion-exchange sites are dispersed in the membranes with high density.(2)Evaluation of ion transport in concentration-cell system using the prepared anion-exchange membrane on the basis of nonequilibrium thermodynamics. Especially, we used the electroconductive membrane permeability that represents the ionic solution/membrane distribution by an electrostatic effect, and the diffusional membrane permeability that represents the ionic migration speed within membrane phase.(3)Evaluation of coexistence effect of electroneutral molecules on radioactive iodine transport through the anion-exchange paper membranes(4)Comparison between an electrodialysis and a diffusional dialysis to separate the radioactive iodine from radioactive waste.We succeeded to develop the anion-exchange paper membrane made of long length pulp fiber bearing trimethyihydroxypropylammonium anion-exchange group. The paper membrane has high permselectivity to iodine. The electroconductive membrane permeability of I-125 to that of Cl-36 reaches 6.2 in the concentration-cell system.