| For nearly half a century,with the increasing consumption of nuclear reactor fuel,the fission products of various elements in the spent fuel treatment process are also increasing,which has brought serious pollution problems to the global environment and aroused widespread concern in the international community.A large amount of iodine isotopes is released,mainly radioactive iodine(I-131),by using fuels lacking energy.Gaseous iodine has the characteristics of fast volatilization,complex chemical form and high fluidity,which is its unique feature.Radioactive gaseous iodine enters the living environment and causes great harm to organisms.I-131is one of the main fission products of nuclear power reactors.It not only causes radionuclide hazards to nuclear power plants,but also causes radionuclide hazards when it is discharged into the process waste gas of nuclear fuel reprocessing plants in the form of organic iodine or elemental iodine.Through the follow-up treatment of spent fuel,the adsorption effects of various adsorption materials were compared,it can be reflected that the silver-coated silica gel has the best adsorption performance.The research group of Tang Jingju an and Ye Mingle et al.studied the saturated adsorption of silver-coated silica gel and silver-coated aluminides on radioactive iodine-containing waste gas.The experimental data reflected that the adsorption capacity and performance of silver-coated silica gel was the most appropriate.In actual nuclear projects such as nuclear power plants and nuclear plants,silver-coated silica gel with silver content of 10%has the highest silver utilization rate,has a good cost-performance ratio,and has a saturated adsorption capacity of238.83 mg/g.That is,in this paper,silver-coated silica gel with different silver content was prepared,and the saturated adsorption capacity of silver-coated silica gel with different adsorption factors was studied.In order to treat radioactive iodine-containing waste gas produced by nuclear engineering in a green way,this research experiment provides self-made silver-coated silica gel with a silver content of about 10%to adsorb radioactive iodine-containing waste gas.Through the dynamic adsorption of silver-coated silica gel,the effects of adsorption factors such as total inlet flow and height of filler layer in adsorption column on the saturated adsorption capacity of silver-coated silica gel were discussed.The adsorption experimental data reflect that changing the inlet flow rate of the adsorption column has little effect on the saturated adsorption capacity of the self-made silver-coated silica gel.Under the condition of small inlet flow rate,the silver-coated silica gel fully contacted with the simulated iodine-containing waste gas,the adsorption time was prolonged,and the adsorption was more saturated.In addition,the height of the filler layer of the silver-coated silica gel in the adsorption column was changed,which had little effect on its mass transfer resistance.The increase of the height of the silver-coated silica gel packing layer in the adsorption column will increase the saturated adsorption capacity of the silver-coated silica gel during the adsorption process,the adsorption effect is almost the same.Under the same other conditions,through dynamic adsorption at different temperatures,it can be found that the adsorption effect of silver-coated silica gel at 150℃is the best,which is consistent with the reference literature.It reflects the effective fitting of Yoon-Nelson model to the adsorption process of silver-coated silica gel on simulated iodine-containing waste gas.The dynamic adsorption of silver coated silica gel for iodine showed that the adsorption capacity of silver coated silica gel for gaseous iodine was 40.60～238.83 mg/g.In addition,silver-coated silica gel has stable properties and lower cost than other adsorbents.It is a promising adsorbent and can be widely used for radioactive iodine produced in spent fuel reprocessing. |
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