"Protium-Tritium" Separation Experiment Of Graphene And Its Radiation Damage Effect

Tritiumis an important resource with a wide range of applications,however the treatment of tritium-containing waste is very difficult.It is important to develop an economical,practical,and efficient hydrogen isotope separation technology,which not only can solve the problem of radioactive waste disposal,but also provide additional tritium supply.Compared with traditional methods,the hydrogen isotope separation method using graphene membranes has the advantages of lower energy consumption,higher separation coefficient,and more simplified equipments.At present,the theoretical calculation of the graphene membrane used in the separation of hydrogen isotopes is relatively mature.However,most experimental researches still stay in the stage of non-radioactive "protium-deuterium" separation.There are few reports on the preparation of the special graphene membrane and its experimental researches on radioactive "protium-tritium" separation.In this paper,the nanoporous graphene membrane for gaseous hydrogen isotope separation and the low-defect graphene composite membrane for "protium-tritium"separation in tritium water were prepared respectively,and the industrial application prospects of the two membranes were compared.After comparison,the low-defect graphene composite separation membrane was selected to study the irradiation effects of tritium water on the damage of graphene and to conduct experiments of"protium-tritium" separation.The main results of the study are as follows:(1)Preparation of the specific graphene membranes for hydrogen isotope separation.Firstly,a nanoporous graphene separation membrane was successfully prepared by irradiating with protons in the accelerator.The pore-density of the nanoporous graphene separation membrane is higher when the monolayer graphene on the nickel substrate was irradiated with low energy and high fluence protons.Secondly,the low-defect graphene composite separation membrane was prepared by ways of hot pressing,etching and electron beam evaporating.Better composite separation membranes were obtained,which depends on the hot pressing conditions(140?,5 MPa,20 min),the etching time(>40 min)and the parameters of electron beam evaporating(deposition rate of 0.1 A/s and a film thickness of 1.8 nm).Finally,the industrial application prospects of the two kinds of graphene separation membranes were compared,and the low-defect graphene composite separation membranes were found to be more practical.(2)Irradiation damage effects of monolayer graphene in tritium water.?-rays with the energy up to 18.6 keV is produced during tritium decay.In order to study the irradiation damages,the monolayer graphene on the copper foil substrate was immersed in heavy water,pure water and tritium water with various specific activities(105 Bq/L?109 Bq/L)for 6 months.Experimental results show that no irradiation damage,morphology and chemical composition changes can be obviously oberseved in graphene within 6 months'irradiation,which primarily show the long service lifetime(>6months)and the feasibility of using graphene for "protium-tritium"separation in tritium water from the perspective of irradiation damages.(3)Experimental researches of "protium-tritium" separation with graphene.The"protium-tritium" separation device with prepared low-defect graphene composite membranes was developed,and experiments of "protium-tritium" separation in tritium water were carried out.Experimental results have shown that the"protium-tritium" separation in tritium water was achieved with this device.The separation effect will increase with the separation voltage and time.For instance,after separated for 15 min and 240 min with the separation voltage of 5 V,the specific activity of the tritium water became 1.17 times and 11.5 times higher than that of before separation.After separated for 15 min and 240 min at separation voltage of 8 V,the specific activity of tritium water became 1.27 times and 12.6 times higher than that of before separation.The above experimental results can verify the feasibility and separation effect of using graphene for "protium-tritium" separation in tritium water.In this paper,the nanoporous graphene membrane for gaseous hydrogen isotope separation and the low-defect graphene composite membrane for tritium water were prepared,respectively.The irradiation damages effects of graphene in tritium water were conducted.Then,"protium-tritium" separation effects in tritium water were studied with the low-defect graphene composite membrane.The experimental data provides important support for future application of graphene to hydrogen isotope separation.