Feasibility of Treatment Agents in Radioactive Iodine Separation from Waste Liquids.

Abstract: To discharge waste liquid containing radioactive iodine into sewage systems, long-term storage or dilution with a large amount of water may be required until the radioactivity concentration reduces below the standard value. Processing the waste liquid could be easier if radioactive iodine could be separated from the water. This study verified the effectiveness of superabsorbent polymer and α-cyclodextrin as treatment agents to separate radioactive iodine from waste liquids. Sodium iodide (Na 125 I) was added to purified water and artificial urine to prepare simulated waste liquids containing iodine equivalent to the urine of patients treated with radioactive iodine. The as-prepared simulated waste liquid was poured into a container with superabsorbent polymer and left for 90 d. The residual iodine rate in the simulated waste liquid was estimated by measuring 125 I radioactivity. When the water was sufficiently dried, residual iodine rates on day 15 were 0.102 and 0.884 in the simulated waste liquids comprising purified water and artificial urine, respectively. The simulated waste liquid comprising purified water with 5% α-cyclodextrin absorbed by 1 g of superabsorbent polymer had a residual rate of 0.980. Moreover, the residual rate of simulated waste liquid comprising artificial urine with 2% α-cyclodextrin absorbed by 1 g of SAP was 0.949. Superabsorbent polymer combined with α-cyclodextrin was an effective treatment agent for separating radioactive iodine from waste liquids.