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

放射性碘广泛用于原子能、医学治疗、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，对健康构成重大危害，因此，世界各国法律对含有放射性碘的放射性废物的使用和处置都有严格的规定。本研究利用阴离子交换纸膜对水中以阴离子形式存在的放射性碘进行浓缩处理，方法如下：(1)开发了四种阴离子交换纸膜，这些阴离子交换位点在膜内高密度分散。(2)基于非平衡热力学评价制备的阴离子交换膜在浓缩池系统中的离子输运。特别地，我们使用了代表离子溶液/膜在静电作用下分布的导电膜渗透率和代表离子在膜相内迁移速度的扩散膜渗透率。(3)评价电子中性分子对放射性碘在阴离子交换纸膜上传输的共存效应。(4)电渗析与扩散渗析分离放射性废物中放射性碘的比较。我们成功地研制了含有三甲基羟丙基阴离子交换基的长纸浆纤维阴离子交换纸膜。纸膜对碘有很高的选择性。在浓缩池体系中，I-125对Cl-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.