| Hydrogen isotopes are of great importance due to their wide applications in the fields of chemical industry, energy sources, material, medical cure and detection as a tracer. However, the natural abundance of deuterium is very small, only about 0.015%, so that how to separate deuterium from hydrogen is quite critical. The heavy isotope of hydrogen, deuterium, is an important material in nuclear industry. Moreover, deuterium and tritium combust less than 10% in the nuclear fusion reactor, thus, from the consideration of self-preserve, economy and environmental safety, they must be recovered and separated in order to recycle them after expelling from the plasma. The traditional methods such as cryogenic distillation, chemical exchange and thermal diffusion require incidental facilities and high-energy cost, therefore, the separation of hydrogen isotopes is received great attention, and how to search for a low cost separation method is a key for the industrial application of deuterium and tritium. The separation cost is usually low if the separation is based on the difference of components in adsorption. And the adsorption method has advantages of simplicity, high reliability and flexible operations, furthermore, the adsorbent can be regenerated easily for reuse, which can avoid environmental pollution due to not eject large amount of tritium radwaste. However, the separation between hydrogen isotopes is difficult due to the similarity of isotopes and small difference of their equilibrium amount adsorbed on common adsorbents. Therefore, how to enhance the difference of components in equilibrium and in dynamic adsorption is a focus on studies of adsorption separation. Based on reasons above, we designed cryogenic adsorption method to study behaviors of hydrogen isotopes on different adsorbents systematically, and mainly contents were as follows:(1) A rapid detection method of hydrogen isotopes was established with conventional gas chromatography that was prepared to test breakthrough curves in the adsorption column.(2) Equilibrium amount adsorbed and kinetic adsorption rate on different molecular sieve adsorbents were measured, and a relative kinetic mathematical model was developed to calculate adsorption rate, from which the highest adsorption capacity was observed at approximately 0.7 nm for hydrogen isotopes, but the largest isotope difference in dynamic adsorption was observed at 0.5 nm and the largest isotope difference in equilibrium adsorption was observed at mesoporous size. (3) A one-column experimental apparatus to separate hydrogen isotopes was designed, and we measured breakthrough curves of hydrogen and deuterium on different adsorbents with it and calculated their separation factors for different pressure, gas flow rate and bed length. The separation efficiency of different adsorbents was discussed under the same experimental condition. Moreover, effects of pore size and specific area to hydrogen isotopes separation were also summarized.(4) A kinetic adsorption mathematical model in the adsorption column for hydrogen isotopes was developed in order to explain and forecast adsorption processes well, and results simulated on the molecular sieves VP800-5 and Y were in good agreement with experimental results. Additionally, different adsorption behaviors in the column were forecasted with this model.
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