Preparation method of material for selective adsorption of iodine-131 nuclide

Abstract

The invention provides a preparation method of a material for selective adsorption of iodine-131 nuclide, and belongs to the technical field of nuclear medicine radioactive wastewater purification treatment.The preparation method comprises the steps that graphite powder, concentrated sulfuric acid, phosphoric acid, potassium permanganate and hydrogen peroxide serve as raw materials to synthesize graphene oxide in a membrane uniform distribution type microreactor; taking the graphene suspension and Zn (NO3). 6H2O as raw materials to synthesize nanoporous graphene in a membrane uniform distribution type microreactor; and sequentially filtering the graphene oxide solution, the nanoporous graphene solution and the graphene oxide solution on a basement membrane to obtain the graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane. According to the preparation method of the material for selective adsorption of the iodine-131 nuclide, provided by the invention, the prepared material for selective adsorption of the iodine-131 nuclide is good in selectivity, high in adsorption capacity and strong in stability.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear medicine radioactive wastewater purification and treatment, and in particular to a method for preparing a material for selective adsorption of iodine-131 nuclides. Background Art

[0002] It has been 108 years since humans discovered the phenomenon of radioactivity. Soon after, nuclear scientists and medical scientists tried to apply radioactive nuclides to medicine, but the real combination of nuclear technology and medicine was in the late 1950s. my country began to use radioactive nuclides to diagnose and treat diseases in 1958. After a long period of research and development, nuclear medicine has emerged and is changing with each passing day. In recent years, with the rapid development of medical science and technology in my country, the use of radioactive isotopes in nuclear medicine has received great attention and development. Its unique advantages in diagnosis and treatment have made nuclear medicine increasingly an important branch of modern medicine. Medical radioactive elements (mostly short half-life nuclides) are mainly used in: equipment and instruments for diagnosing diseases, such as 68 Ge is used in the calibration of computerized X-ray tomography (PET-CT) devices, etc.; drugs for diagnosing diseases, such as ECT imaging drugs 99m Radioisotopes used in Tc and PET / CT diagnosis 18 F, etc.; drugs for treating diseases, such as 131 I is used to treat hyperthyroidism, 125 I particles are used to treat tumor diseases, etc.

[0003] With the rapid development of nuclear energy technology, nuclear safety issues have attracted more and more attention. The composition of hospital sewage is complex. If it is discharged directly into natural water bodies without treatment, it will cause very serious pollution to the soil and surrounding waters, and become an important way for the spread of epidemics, which will greatly harm people's daily lives. Hospital sewage mainly comes from the drainage of different departments such as operating rooms, X-ray imaging and printing, wards, isotope therapy diagnosis, laboratories, and treatment rooms. According to the different sewage components and water volumes discharged by each department, it is mainly divided into heavy metal wastewater, oily wastewater, printing wastewater, radioactive wastewater, etc. Among them, the radioactive sewage (waste) water generated in the nuclear medicine practice process mainly comes from the excrement (including vomitus) of patients and examinees, the residual liquid of radionuclide agents, the induced radioactive cooling water, the radionuclide agent display vessels, and the washing and drainage of nuclear medicine staff. If the radioactive sewage is discharged and treated improperly, it will cause environmental pollution and endanger public safety and health. Among them, unstable radionuclides spontaneously emit α, β and γ rays through their own decay. These rays have specific energies and have different penetration and ionization abilities on cells, skin, bones, internal organs and other tissues in the human body, thereby inducing different degrees of physical, chemical or biochemical changes in the human body. When exposed to a large radiation dose, it will act on the human body, directly destroy the molecular structure of substances in the human body, break the protein molecular bonds and RNA bonds, and cause enzymes that are important to the human body to lose their corresponding biological activity and cannot work normally, thus leading to a series of major diseases such as hair loss, skin erythema, leukopenia or thrombocytopenia, cataracts, liver and kidney failure, etc., and can directly cause death under high-dose irradiation.

[0004] Radioactive wastewater treatment technologies mainly include: natural decay method, chemical precipitation method, ion exchange method, adsorption method, evaporation concentration, membrane separation technology, biological treatment method, magnetic-molecular method, inert solidification method, etc. 131 I. 99m Tc, etc.) have short half-life of radionuclides, few types of radionuclides, and low total activity of radionuclides, so the methods for treating radioactive medical wastewater generally use decay method, dilution method and adsorption ion exchange. Among them, the natural decay method and dilution method store radioactive wastewater with a longer half-life in containers according to the different half-life of radioactive wastewater, and discharge radioactive wastewater with a shorter half-life into decay pools for treatment. If the radioactive wastewater still does not meet the standards after being treated in the decay pool, the dilution method can be used - mixing with other medical wastewater in the hospital area to further reduce the concentration.

[0005] Traditional sewage treatment methods such as chemical precipitation, ion exchange, and evaporation have their own advantages and disadvantages, and can treat radioactive wastewater to a certain extent. Usually, chemical precipitation, ion exchange / adsorption and other methods can be used as effective pretreatment methods for the treatment of radioactive wastewater. As a relatively new sewage treatment method, membrane separation technology has a wide range of applications, simple operation, low energy consumption, and good effluent quality. It is an efficient separation method. In modern sewage treatment technology, membrane separation technology is often combined with traditional processes to obtain a higher decontamination factor (DF) and concentration factor (CF). The biological method has low cost, high concentration factor, and no secondary pollution, but it also has great limitations. It is necessary to find organisms suitable for different radioactive nuclides, and it is also necessary to consider their living environment, so it is less practical. Comprehensive analysis shows that various methods have certain limitations, which can be compensated by combined processes. The most widely used combined processes are membrane separation and adsorption or chemical precipitation.

[0006] At present, the more mature treatment method for iodine-131 nuclides in radioactive waste liquid is to use materials such as activated carbon for adsorption. Although there are some iodine-131 adsorption materials on the market, they usually have problems such as poor selectivity, low adsorption capacity and insufficient stability. For example, traditional adsorption materials may have weak adsorption capacity for iodine-131 and are easily interfered by other ions, resulting in poor results in practical applications. In addition, some adsorption materials are prone to lose adsorption properties in a radiation environment, which limits their application at nuclear accident sites.

[0007] Therefore, there is an urgent need for a method for preparing a material for selective adsorption of iodine-131 nuclides with good selectivity, high adsorption capacity and strong stability. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method for preparing a material for selective adsorption of iodine-131 nuclides with good selectivity, high adsorption capacity and strong stability.

[0009] In order to solve the above technical problems, the present invention provides a method for preparing a material for selective adsorption of iodine-131 nuclides, comprising the following steps: Graphene oxide was synthesized in a membrane-distributed microreactor using graphite powder, concentrated sulfuric acid, phosphoric acid, potassium permanganate and hydrogen peroxide as raw materials. Nanoporous graphene was synthesized in a uniformly distributed membrane microreactor using graphene suspension and Zn(NO3)·6H2O as raw materials. The graphene oxide solution, the nanoporous graphene solution and the graphene oxide solution are filtered on the base membrane in sequence to obtain a graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane.

[0010] Furthermore, the uniformly distributed membrane microreactor comprises a tubular membrane and a reaction container, wherein the tubular membrane is arranged in the middle of the reaction container, and a magnetic stirring rotor is arranged at the bottom of the reaction container; The tubular membrane is coiled into a spiral shape of 3-6 turns with a diameter of 4-6 mm, and the diameter of the dispersed pores on the tubular membrane is 0.1-0.5 μm; The rotation speed of the magnetic stirring rotor at the bottom of the reaction container is 50-200 rpm.

[0011] Furthermore, the membrane uniformly distributed microreactor comprises the following steps when used: The continuous phase was placed in a reaction vessel and stirred with a magnetic stirring rotor. One end of the tubular membrane is blocked, and the dispersed phase is injected from the other end of the tubular membrane at a flow rate of 0.1-1 mL / min through a metering pump; The dispersed phase in the form of droplets seeps out from the dispersed pores of the tubular membrane and contacts and reacts with the continuous phase.

[0012] Furthermore, the synthesis of graphene oxide comprises the following steps: 0.5-2 g of graphite powder and 10-20 ml of concentrated sulfuric acid are added into a uniformly distributed membrane microreactor and stirred and mixed using a magnetic stirring rotor to obtain a mixture; A mixture formed by mixing 0.5-2.5 mL of phosphoric acid and 3-10 g of potassium permanganate is added to the mixture in multiple portions, and stirred at 0-10° C. for 0.5-2 h to obtain a pre-reaction solution; Heat the pre-reaction solution to 40-90° C., and continue stirring the reaction for 10-15 hours to obtain a post-reaction solution; The reaction solution was cooled to room temperature and poured into ice water, and 0.5-5 mL of hydrogen peroxide was added through the spiral tubular membrane of the membrane uniformly distributed microreactor under stirring to continue the reaction; After the solution turns golden yellow, the reaction product is obtained by filtration; The reaction product was washed with distilled water and 2-10 vol% hydrochloric acid to a pH of 6-8; The washed product was dispersed in water and ultrasonicated for 5-10 hours, and then vacuum freeze-dried to obtain graphene oxide powder.

[0013] Furthermore, the graphite powder is flaky graphite powder with a particle size of 100-1000 meshes, and the phosphoric acid is AR pure phosphoric acid.

[0014] Furthermore, the membrane uniformly distributed microreactor used for graphene oxide synthesis is a tubular membrane wound into a spiral shape with 4 turns, with a diameter of 5 mm, a dispersion pore diameter of 0.1-0.5 μm, an external magnetic stirring speed of 100-200 rpm, and a flow rate of phosphoric acid passing into the tubular membrane of 0.1-1 mL / min.

[0015] Furthermore, the synthesis of the nanoporous graphene comprises the following steps: The synthesized graphene oxide is added with water to prepare a graphene suspension of 0.5-5 g / L; 0.5-5 g / L graphene suspension and 400-800 g / L Zn(NO3)·6H2O are mixed in a membrane uniformly distributed microreactor at a volume ratio of 1:1-1:3 to obtain a mixed turbid liquid; The mixed turbid liquid is vacuum filtered to obtain a filter cake; The filter cake and the filter paper are dried at 50-70° C. and then burned. The combustion residue is washed with HCl and deionized water to obtain nanoporous graphene.

[0016] Furthermore, the membrane uniformly distributed microreactor used for the nanoporous graphene synthesis is a tubular membrane wound into a spiral shape with 6 turns, with a diameter of 4 mm, a dispersed pore diameter of 0.1-0.5 μm, an external magnetic stirring speed of 100-200 rpm, and the flow rate of the graphene suspension and Zn(NO3)·6H2O passing into the tubular membrane is 0.2-0.5 mL / min.

[0017] Furthermore, the synthesis of the graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane comprises the following steps: The prepared nanoporous graphene and graphene oxide are respectively prepared into 1-5 g / L nanoporous graphene turbid solution and 0.1-0.8 g / L graphene oxide turbid solution; Using a polyethersulfone ultrafiltration membrane as a basement membrane, 1-5 mL of graphene oxide, 1-5 mL of nanoporous graphene turbid solution, and 1-5 mL of graphene oxide turbid solution are filtered through the basement membrane in a negative pressure filtration manner to obtain a loaded basement membrane; The supported substrate membrane is vacuum dried to obtain a graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane two-dimensional separation membrane.

[0018] Furthermore, the vacuum drying of the supported substrate membrane is to place the supported substrate membrane in a vacuum drying oven and dry it at room temperature for 20-30 hours.

[0019] The present invention provides a method for preparing a material for selective adsorption of iodine-131 nuclides. A uniformly distributed membrane microreactor is used in the preparation process, and the internal structure and specific surface area of ​​the prepared adsorption material are controlled by adjusting relevant parameters such as the membrane pipe diameter, the size of the distributed small holes in the membrane pipe, the number of winding circles and the diameter of the membrane pipe of the uniformly distributed membrane microreactor. The amplification effect and unevenness in the preparation process can be greatly reduced, and the size and morphology of the internal particles and pores of the prepared adsorption material can be more uniform. The size of the internal particles and pores of the prepared adsorption material can be reduced by 20-30% on average, which increases the specific surface area of ​​the material and greatly increases the active adsorption sites, thereby greatly improving the adsorption effect of the adsorption material. Compared with traditional adsorption materials, the selective adsorption capacity of the adsorption material prepared by the present invention for iodine-131 nuclides is improved by 10-40%, and the purification coefficient is improved to 40-50, which is 4-5 times higher than that of traditional adsorption materials.

[0020] Therefore, the present invention provides a method for preparing a material for selective adsorption of iodine-131 nuclides. The prepared adsorption material is used to treat iodine-131 nuclides in radioactive wastewater (wastewater), and has higher selectivity and stronger adsorption capacity, making the treated radioactive wastewater (wastewater) safer and more environmentally friendly, truly achieving the principle of "minimizing radioactive waste". BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method for preparing a material for selective adsorption of iodine-131 nuclides provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a uniformly distributed membrane microreactor in a material preparation method for selective adsorption of iodine-131 nuclides provided in an embodiment of the present invention.

[0022] Description of reference numerals: 1- tubular membrane, 2- reaction vessel, 3- magnetic stirring rotor. DETAILED DESCRIPTION

[0023] See also Figure 1 , a method for preparing a material for selective adsorption of iodine-131 nuclides provided by an embodiment of the present invention comprises the following steps: Step 1) Graphene oxide is synthesized in a membrane uniformly distributed microreactor using graphite powder, concentrated sulfuric acid, phosphoric acid, potassium permanganate and hydrogen peroxide as raw materials.

[0024] Among them, see Figure 2The membrane uniformly distributed microreactor comprises a tubular membrane 1 and a reaction container 2, wherein the tubular membrane 1 is arranged in the middle of the reaction container 2, and a magnetic stirring rotor 3 is arranged at the bottom of the reaction container 2. The tubular membrane 1 is wound into a spiral shape with 3-6 turns, and the diameter is 4-6 mm, and the tubular membrane 1 is uniformly dispersed with dispersed pores with a diameter of 0.1-0.5 μm. The rotation speed of the magnetic stirring rotor 3 at the bottom of the reaction container 2 is 50-200 rpm.

[0025] When using a uniformly distributed membrane microreactor, the continuous phase is placed in a reaction container 2 and stirred by a magnetic stirring rotor 3, then one end of the tubular membrane 1 is blocked, and the dispersed phase is injected from the other end of the tubular membrane 1 at a flow rate of 0.1-1 mL / min by a metering pump. The dispersed phase enters the tubular membrane 1 and seeps out from each dispersed hole of the tubular membrane 1 in the form of droplets to contact the continuous phase. The seeped dispersed phase is fully mixed with the continuous phase under the stirring action of the magnetic stirring rotor 3 to react.

[0026] The synthesis of graphene oxide is based on the improved Hummers method, which specifically includes the following steps: 1. Add 0.5-2g of graphite powder and 10-20ml of concentrated sulfuric acid as a continuous phase into the reaction vessel 2 of the membrane uniformly distributed microreactor in advance, start the magnetic stirring rotor 3 at the bottom of the reaction vessel 2, and stir the mixture of graphite powder and concentrated sulfuric acid at a speed of 100-200rpm.

[0027] 2. Block one end of the tubular membrane 1, and inject a mixed solution of 0.5-2.5 mL of phosphoric acid and 3-10 g of potassium permanganate as a dispersed phase into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.1-1 mL / min in multiple times through a metering pump.

[0028] As a specific embodiment of the present invention, 0.5-2.5 mL of phosphoric acid and 3-10 g of potassium permanganate are mixed and added to the tubular membrane 1 in 2-5 times, so that the graphite powder can be oxidized into graphene oxide by potassium permanganate in an acidic environment.

[0029] 3. The mixed solution of phosphoric acid and potassium permanganate seeps out from the dispersed pores of the tubular membrane 1 and enters the mixture of graphite powder and concentrated sulfuric acid in the form of droplets. It is stirred at a temperature of 0-10°C for 0.5-2h to allow sulfuric acid and potassium permanganate to be inserted between the graphite layers and pre-oxidized, thereby obtaining a pre-reaction solution.

[0030] By carrying out the reaction in a uniformly distributed membrane microreactor, high-viscosity phosphoric acid can be stably and minutely reacted with the reactants through the spiral membrane pipeline to undergo an improved Hummers reaction, thereby enhancing the mixing effect and making the particle distribution on the material surface more fine and uniform.

[0031] 4. Continue to heat the pre-reaction solution to raise the temperature to 40-90°C, continue stirring and react for 10-15 hours, dissociate and remove the sulfur-containing groups generated in the oxidation process, and obtain a post-reaction solution.

[0032] 5. After cooling the reaction solution to room temperature, pour it into ice water, add 0.5-5 mL of hydrogen peroxide through the tubular membrane 1 of the membrane uniformly distributed microreactor under stirring to continue the reaction, and remove excess potassium permanganate in the reaction solution.

[0033] 6. After the solution turns golden yellow, filter to obtain the reaction product.

[0034] 7. Wash the reaction product with distilled water and 2-10 vol% hydrochloric acid respectively until the pH is 6-8.

[0035] 8. Disperse the washed product in water and ultrasonicate for 5-10 hours, then freeze-dry in a vacuum to prevent the graphene oxide from decomposing and reducing at high temperature while maintaining its fluffy structure, thereby obtaining graphene oxide powder.

[0036] The graphite powder is flaky graphite powder with a particle size of 100-1000 meshes, and the phosphoric acid is AR pure phosphoric acid.

[0037] As a specific embodiment of the present invention, the membrane uniformly distributed microreactor used for synthesizing graphene oxide is a tubular membrane 1 wound into a spiral shape with 4 turns, with a diameter of 5 mm, a diameter of the dispersed holes on the tubular membrane 1 of 0.1-0.5 μm, an external magnetic stirring speed of 100-200 rpm, and a flow rate of phosphoric acid passing into the tubular membrane 1 of 0.1-1 mL / min.

[0038] Step 2) Nanoporous graphene is synthesized in a uniformly distributed membrane microreactor using graphene suspension and Zn(NO3)·6H2O solution as raw materials.

[0039] The synthesis of nanoporous graphene includes the following steps: 1. Add the synthesized graphene oxide and water as a continuous phase into the reaction vessel 2 of the membrane uniformly distributed microreactor in advance, start the magnetic stirring rotor 3 at the bottom of the reaction vessel 2, and stir the mixture of the synthesized graphene oxide and water at a speed of 100-200 rpm to prepare a graphene suspension of 0.5-5 g / L.

[0040] 2. Block one end of the tubular membrane 1, and inject 400-800 g / L Zn(NO3)·6H2O solution with a volume ratio of 1:1-1:3 to 0.5-5 g / L graphene suspension as a dispersed phase into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.2-0.5 mL / min through a metering pump. The Zn(NO3)·6H2O solution seeps out from each dispersed hole of the tubular membrane 1 and enters the graphene suspension in the form of droplets. Under the continuous stirring action of the magnetic stirring rotor 3, the two are mixed and reacted for 0.5-3 hours to obtain a mixed turbid solution.

[0041] 3. The mixed turbid liquid is vacuum filtered to obtain a filter cake, and Zn(NO3)·6H2O is inserted between the graphene layers.

[0042] 4. Dry the filter cake and filter paper in an oven at 50-70℃ for 2 h to remove the residual moisture in the filter cake. Then ignite the dried filter cake with an alcohol lamp. After 5-10 s of intense combustion, the oxygen-containing groups on the graphene surface are burned and consumed. Finally, wash with HCl and deionized water to remove the combustion residues on the graphene surface, and nanoporous graphene can be obtained.

[0043] Among them, the membrane uniformly distributed microreactor used in synthesizing nanoporous graphene is a tubular membrane wound into a spiral shape with 6 turns, with a diameter of 4mm, a dispersed pore diameter of 0.1-0.5μm, an external magnetic stirring speed of 100-200rpm, and the flow rate of the graphene suspension and Zn(NO3)·6H2O passing into the tubular membrane is 0.2-0.5mL / min.

[0044] Step 3) Filtering the graphene oxide solution, the nanoporous graphene solution and the graphene oxide solution on the substrate membrane in sequence to obtain a graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane. Specifically, the steps include: 1. Add water to the prepared nanoporous graphene and graphene oxide to prepare 1-5 g / L nanoporous graphene turbid solution and 0.1-0.8 g / L graphene oxide turbid solution respectively.

[0045] 2. Using polyethersulfone ultrafiltration membrane as base membrane, first filter 1-5 mL of graphene oxide turbid solution through the base membrane by negative pressure filtration, then filter 1-5 mL of nanoporous graphene turbid solution on the base membrane by the same method, and then filter 1-5 mL of graphene oxide turbid solution on the base membrane to obtain a loaded base membrane.

[0046] 3. Place the loaded substrate membrane in a vacuum drying oven and dry it at room temperature for 20-30 h to obtain a two-dimensional separation membrane of graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane.

[0047] The present invention provides a method for preparing a material for selective adsorption of iodine-131 nuclides. A uniformly distributed membrane microreactor is used in the preparation process, and the internal structure and specific surface area of ​​the prepared adsorption material are controlled by regulating relevant parameters such as the membrane pipe diameter, the size of the distributed small holes in the membrane pipe, the number of winding circles and the diameter of the membrane pipe of the uniformly distributed membrane microreactor. The amplification effect and unevenness in the preparation process can be greatly reduced, and the size and morphology of the internal particles and pores of the prepared adsorption material can be more uniform. The size of the internal particles and pores of the prepared adsorption material can be reduced by 20-30% on average, which increases the specific surface area of ​​the material and greatly increases the active adsorption sites, thereby greatly improving the adsorption effect of the adsorption material. Compared with traditional adsorption materials, the selective adsorption capacity of the adsorption material prepared by the present invention for iodine-131 nuclides is improved by 10-40%, and the purification coefficient is improved to 40-50, which is 4-5 times higher than that of traditional adsorption materials. The adsorption material prepared in this way can be used to treat iodine-131 nuclides in radioactive wastewater, which has higher selectivity and stronger adsorption capacity, making the treated radioactive wastewater safer and more environmentally friendly, truly achieving the principle of "minimizing radioactive waste".

[0048] The following is a specific description of a method for preparing a material for selective adsorption of iodine-131 nuclides provided by the present invention through examples.

[0049] Example 1 S1: 0.5 g of 100-mesh flaky graphite powder and 10 ml of AR pure concentrated sulfuric acid as a continuous phase are added in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor with a diameter of 5 mm and a dispersed pore diameter of 0.1 μm and whose magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of graphite powder and concentrated sulfuric acid at a rotation speed of 100 rpm.

[0050] S2: One end of the tubular membrane 1 is blocked, and a mixed solution of 0.5 mL of phosphoric acid and 3 g of potassium permanganate is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.1 mL / min in two times through a metering pump as a dispersed phase. The mixed solution of phosphoric acid and potassium permanganate seeps out from each dispersed hole of the tubular membrane 1, enters the mixture of graphite powder and concentrated sulfuric acid in the form of droplets, and feeds and reacts through the membrane uniformly distributed microreactor, so that the high-viscosity phosphoric acid can pass through the spiral membrane pipeline stably and in trace amounts to undergo an improved Hummers reaction with the reactants, which can enhance the mixing effect and make the surface particle distribution of the prepared material more fine and uniform.

[0051] The reactants were first stirred and reacted at a temperature of 0° C. for 0.5 h, so that sulfuric acid and potassium permanganate were inserted between the graphite layers and pre-oxidized to obtain a pre-reaction solution.

[0052] S3: Continue to heat the pre-reaction solution to raise the temperature to 40° C., continue to stir the reaction for 10 hours, dissociate and remove the sulfur-containing groups generated in the oxidation process, and obtain a post-reaction solution.

[0053] S4: The post-reaction solution is cooled to room temperature and poured into ice water. Under stirring, 0.5 mL of hydrogen peroxide is added through the tubular membrane 1 of the membrane uniformly distributed microreactor to continue the reaction. Excess potassium permanganate in the post-reaction solution is removed until the post-reaction solution turns golden yellow and then filtered to obtain the reaction product.

[0054] S5: The reaction product is washed with distilled water and 2 vol% hydrochloric acid to a pH of 6, and then the washed product is dispersed in water and ultrasonically treated for 5 hours. Finally, the ultrasonically treated product is vacuum freeze-dried to avoid decomposition and reduction of graphene oxide at high temperature while maintaining its own fluffy structure, thereby obtaining graphene oxide powder.

[0055] S6: The graphene oxide synthesized in S5 and water are added as a continuous phase in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor with a diameter of 4 mm and a dispersed pore diameter of 0.1 μm and the magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of the synthesized graphene oxide and water at a rotation speed of 100 rpm to prepare a graphene suspension of 0.5 g / L.

[0056] S7: One end of the tubular membrane 1 is blocked, and a 400 g / L Zn(NO3)·6H2O solution with a volume ratio of 1:1 to 0.5 g / L graphene suspension is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.2 mL / min through a metering pump. The Zn(NO3)·6H2O solution seeps out from each dispersed hole of the tubular membrane 1 and enters the graphene suspension in the form of droplets. Under the continuous stirring action of the magnetic stirring rotor 3, the two are mixed and reacted for 0.5 h to obtain a mixed turbid solution.

[0057] S8: The mixed turbid liquid is vacuum filtered to obtain a filter cake, and Zn(NO3)·6H2O is inserted between the graphene layers.

[0058] S9: Place the filter cake and filter paper in an oven at 50°C and dry for 2 h to remove the residual moisture in the filter cake. Then, ignite the dried filter cake with an alcohol lamp. After a 5-second intense combustion process, the oxygen-containing groups on the graphene surface are burned and consumed. Finally, HCl and deionized water are used to wash and remove the combustion residues on the graphene surface to obtain nanoporous graphene.

[0059] S10: The nanoporous graphene prepared in S9 and the graphene oxide prepared in S5 are added with water to prepare 1 g / L nanoporous graphene turbid solution and 0.1 g / L graphene oxide turbid solution respectively.

[0060] S11: Using a polyethersulfone ultrafiltration membrane as a base membrane, first filter 1 mL of graphene oxide turbid solution through the base membrane by negative pressure filtration, then filter 1 mL of nanoporous graphene turbid solution on the base membrane by the same method, and then filter 1 mL of graphene oxide turbid solution on the base membrane to obtain a loaded base membrane.

[0061] S12: placing the loaded substrate membrane in a vacuum drying oven and drying it at room temperature for 20 hours to obtain a graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane two-dimensional separation membrane.

[0062] The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention can have a particle and pore size of 160-300nm inside the material, which is 20-30% smaller than that of the traditional adsorption material, thus greatly increasing the specific surface area of ​​the material, greatly increasing the active adsorption sites of the material, and achieving better adsorption effect. The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention is used to adsorb iodine-131 nuclides in radioactive waste liquid, and the selective adsorption capacity of iodine-131 in a radioactive environment can reach 250-350mg / g, which is 10-40% higher than that of the traditional adsorption material, and the purification coefficient can be increased to 40-50, which is 4-5 times higher than that of the traditional adsorption material.

[0063] Example 2 S1: 2 g of flaky graphite powder with a particle size of 1000 mesh and 20 ml of AR pure concentrated sulfuric acid as a continuous phase are added in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor with a diameter of 5 mm and a dispersed pore diameter of 0.5 μm and whose magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of graphite powder and concentrated sulfuric acid at a rotation speed of 200 rpm.

[0064] S2: One end of the tubular membrane 1 is blocked, and a mixed solution of 2.5 mL of phosphoric acid and 10 g of potassium permanganate is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 1 mL / min in 5 times through a metering pump as a dispersed phase. The mixed solution of phosphoric acid and potassium permanganate seeps out from each dispersed hole of the tubular membrane 1, enters the mixture of graphite powder and concentrated sulfuric acid in the form of droplets, and feeds and reacts through the membrane uniformly distributed microreactor, so that the high-viscosity phosphoric acid can pass through the spiral membrane pipeline stably and in trace amounts to undergo an improved Hummers reaction with the reactants, which can enhance the mixing effect and make the surface particle distribution of the prepared material more fine and uniform.

[0065] The reactants were first stirred and reacted at a temperature of 10° C. for 2 h, so that sulfuric acid and potassium permanganate were inserted between the graphite layers and pre-oxidized to obtain a pre-reaction solution.

[0066] S3: Continue to heat the pre-reaction solution to raise the temperature to 90° C., continue to stir the reaction for 15 hours, dissociate and remove the sulfur-containing groups generated in the oxidation process, and obtain a post-reaction solution.

[0067] S4: The post-reaction solution is cooled to room temperature and poured into ice water. 5 mL of hydrogen peroxide is added through the tubular membrane 1 of the membrane uniformly distributed microreactor under stirring to continue the reaction. Excess potassium permanganate in the post-reaction solution is removed until the post-reaction solution turns golden yellow and then filtered to obtain the reaction product.

[0068] S5: The reaction product is washed with distilled water and 10 vol% hydrochloric acid respectively to a pH of 8, and then the washed product is dispersed in water and ultrasonically treated for 10 hours. Finally, the ultrasonically treated product is vacuum freeze-dried to avoid decomposition and reduction of graphene oxide at high temperature while maintaining its own fluffy structure, thereby obtaining graphene oxide powder.

[0069] S6: The graphene oxide synthesized in S5 and water are added as a continuous phase in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor wound in a spiral shape with 6 turns, a diameter of 4 mm, and a dispersed pore diameter of 0.1-0.5 μm. The magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of the synthesized graphene oxide and water at a rotation speed of 200 rpm to prepare a graphene suspension of 5 g / L.

[0070] S7: One end of the tubular membrane 1 is blocked, and a 400-800 g / L Zn(NO3)·6H2O solution with a volume ratio of 1:3 to 5 g / L graphene suspension is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.5 mL / min through a metering pump. The Zn(NO3)·6H2O solution seeps out from each dispersed hole of the tubular membrane 1 and enters the graphene suspension in the form of droplets. Under the continuous stirring action of the magnetic stirring rotor 3, the two are mixed and reacted for 3 hours to obtain a mixed turbid solution.

[0071] S8: The mixed turbid liquid is vacuum filtered to obtain a filter cake, and Zn(NO3)·6H2O is inserted between the graphene layers.

[0072] S9: Place the filter cake and filter paper in an oven at 70°C and dry for 2 h to remove the residual moisture in the filter cake. Then, ignite the dried filter cake with an alcohol lamp. After a 10-second intense combustion process, the oxygen-containing groups on the graphene surface are burned and consumed. Finally, the combustion residues on the graphene surface are washed with HCl and deionized water to obtain nanoporous graphene.

[0073] S10: The nanoporous graphene prepared in S9 and the graphene oxide prepared in S5 were added with water to prepare 5 g / L nanoporous graphene turbid solution and 0.8 g / L graphene oxide turbid solution respectively.

[0074] S11: Using polyethersulfone ultrafiltration membrane as base membrane, first filter 5 mL of graphene oxide turbid solution through the base membrane by negative pressure filtration, then filter 5 mL of nanoporous graphene turbid solution on the base membrane by the same method, and then filter 5 mL of graphene oxide turbid solution on the base membrane to obtain a loaded base membrane.

[0075] S12: The loaded substrate membrane is placed in a vacuum drying oven and dried at room temperature for 30 h to obtain a graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane two-dimensional separation membrane.

[0076] The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention can have a particle and pore size of 40-100nm inside the material, which is 20-30% smaller than that of the traditional adsorption material on average, thus greatly increasing the specific surface area of ​​the material, greatly increasing the active adsorption sites of the material, and achieving better adsorption effect. The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention is used to adsorb iodine-131 nuclides in radioactive waste liquid, and the selective adsorption capacity of iodine-131 in a radioactive environment can reach 350-550mg / g, which is 10-40% higher than that of the traditional adsorption material, and the purification coefficient can be increased to 40-50, which is 4-5 times higher than that of the traditional adsorption material.

[0077] Example 3 S1: 1.5 g of flaky graphite powder with a particle size of 500 mesh and 15 ml of AR pure concentrated sulfuric acid as a continuous phase are added in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor with a diameter of 5 mm and a dispersed pore diameter of 0.3 μm and whose magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of graphite powder and concentrated sulfuric acid at a rotation speed of 150 rpm.

[0078] S2: One end of the tubular membrane 1 is blocked, and a mixed solution of 1.5 mL of phosphoric acid and 6 g of potassium permanganate is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.5 mL / min in 4 times through a metering pump as a dispersed phase. The mixed solution of phosphoric acid and potassium permanganate seeps out from each dispersed hole of the tubular membrane 1, enters the mixture of graphite powder and concentrated sulfuric acid in the form of droplets, and feeds and reacts through the membrane uniformly distributed microreactor, so that the high-viscosity phosphoric acid can pass through the spiral membrane pipeline stably and in trace amounts to undergo an improved Hummers reaction with the reactants, which can enhance the mixing effect and make the surface particle distribution of the prepared material more fine and uniform.

[0079] The reactants were first stirred and reacted at a temperature of 5° C. for 1.5 h, so that sulfuric acid and potassium permanganate were inserted between the graphite layers and pre-oxidized to obtain a pre-reaction solution.

[0080] S3: Continue to heat the pre-reaction solution to raise the temperature to 70° C., continue to stir the reaction for 13 hours, dissociate and remove the sulfur-containing groups generated in the oxidation process, and obtain a post-reaction solution.

[0081] S4: The post-reaction solution is cooled to room temperature and poured into ice water. 3 mL of hydrogen peroxide is added through the tubular membrane 1 of the membrane uniformly distributed microreactor under stirring to continue the reaction. Excess potassium permanganate in the post-reaction solution is removed until the post-reaction solution turns golden yellow and then filtered to obtain the reaction product.

[0082] S5: The reaction product is washed with distilled water and 6 vol% hydrochloric acid to a pH of 7, and then the washed product is dispersed in water and ultrasonically treated for 7 hours. Finally, the ultrasonically treated product is vacuum freeze-dried to avoid decomposition and reduction of graphene oxide at high temperature while maintaining its own fluffy structure, thereby obtaining graphene oxide powder.

[0083] S6: The graphene oxide synthesized in S5 and water are added as a continuous phase in advance into a reaction vessel 2 of a membrane uniformly distributed microreactor whose tubular membrane 1 is a membrane uniformly distributed microreactor with a diameter of 4 mm and a dispersed pore diameter of 0.3 μm and whose tubular membrane 1 is wound in a spiral shape with 6 turns. The magnetic stirring rotor 3 at the bottom of the reaction vessel 2 is started to stir the mixture of the synthesized graphene oxide and water at a rotation speed of 150 rpm to prepare a 2.5 g / L graphene suspension.

[0084] S7: One end of the tubular membrane 1 is blocked, and a 600 g / L Zn(NO3)·6H2O solution with a volume ratio of 1:2 to 2.5 g / L graphene suspension is injected into the tubular membrane 1 from the other end of the tubular membrane 1 at a flow rate of 0.25 mL / min through a metering pump. The Zn(NO3)·6H2O solution seeps out from each dispersed hole of the tubular membrane 1 and enters the graphene suspension in the form of droplets. Under the continuous stirring action of the magnetic stirring rotor 3, the two are mixed and reacted for 1.5 hours to obtain a mixed turbid solution.

[0085] S8: The mixed turbid liquid is vacuum filtered to obtain a filter cake, and Zn(NO3)·6H2O is inserted between the graphene layers.

[0086] S9: Dry the filter cake and filter paper in an oven at 50-70°C for 2 h to remove the residual moisture in the filter cake, and then ignite the dried filter cake with an alcohol lamp. After a 7-second intense combustion process, the oxygen-containing groups on the graphene surface are burned and consumed. Finally, the combustion residues on the graphene surface are washed with HCl and deionized water to obtain nanoporous graphene.

[0087] S10: The nanoporous graphene prepared in S9 and the graphene oxide prepared in S5 were added with water to prepare 2.5 g / L nanoporous graphene turbid solution and 0.5 g / L graphene oxide turbid solution respectively.

[0088] S11: Using polyethersulfone ultrafiltration membrane as base membrane, first filter 2.5 mL of graphene oxide turbid solution through the base membrane by negative pressure filtration, then filter 2.5 mL of nanoporous graphene turbid solution on the base membrane by the same method, and then filter 2.5 mL of graphene oxide turbid solution on the base membrane to obtain a loaded base membrane.

[0089] S12: placing the loaded substrate membrane in a vacuum drying oven and drying it at room temperature for 25 hours to obtain a graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane two-dimensional separation membrane.

[0090] The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention can have a particle and pore size of 80-200nm inside the material. Compared with the traditional adsorption material, the particle and pore size inside the material are reduced by an average of 20-30%, which greatly increases the specific surface area of ​​the material, greatly increases the active adsorption sites of the material, and has a better adsorption effect. The graphene oxide film / nanoporous graphene film / graphene oxide film two-dimensional separation membrane prepared in the embodiment of the present invention is used to adsorb iodine-131 nuclides in radioactive waste liquid. The selective adsorption capacity of iodine-131 in a radioactive environment can reach 300-450mg / g, which is 10-40% higher than that of traditional adsorption materials, and the purification coefficient can be increased to 40-50, which is 4-5 times higher than that of traditional adsorption materials.

[0091] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a material for selective adsorption of iodine-131 nuclides, characterized in that: The steps include: Graphene oxide was synthesized in a membrane-distributed microreactor using graphite powder, concentrated sulfuric acid, phosphoric acid, potassium permanganate and hydrogen peroxide as raw materials. Nanoporous graphene was synthesized in a uniformly distributed membrane microreactor using graphene suspension and Zn(NO3)·6H2O as raw materials. The graphene oxide solution, the nanoporous graphene solution and the graphene oxide solution are filtered on the base membrane in sequence to obtain a graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane.

2. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 1, characterized in that: The membrane uniformly distributed microreactor comprises a tubular membrane and a reaction container, wherein the tubular membrane is arranged in the middle of the reaction container, and a magnetic stirring rotor is arranged at the bottom of the reaction container; The tubular membrane is coiled into a spiral shape of 3-6 turns with a diameter of 4-6 mm, and the diameter of the dispersed pores on the tubular membrane is 0.1-0.5 μm; The rotation speed of the magnetic stirring rotor at the bottom of the reaction container is 50-200 rpm.

3. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 2, characterized in that: The membrane uniformly distributed microreactor comprises the following steps when used: The continuous phase was placed in a reaction vessel and stirred with a magnetic stirring rotor. One end of the tubular membrane is blocked, and the dispersed phase is injected from the other end of the tubular membrane at a flow rate of 0.1-1 mL / min through a metering pump; The dispersed phase in the form of droplets seeps out from the dispersed pores of the tubular membrane and contacts and reacts with the continuous phase.

4. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 1, characterized in that: The synthesis of graphene oxide comprises the following steps: 0.5-2 g of graphite powder and 10-20 ml of concentrated sulfuric acid are added into a uniformly distributed membrane microreactor and stirred and mixed using a magnetic stirring rotor to obtain a mixture; A mixture formed by mixing 0.5-2.5 mL of phosphoric acid and 3-10 g of potassium permanganate is added to the mixture in multiple portions, and stirred at 0-10° C. for 0.5-2 h to obtain a pre-reaction solution; Heat the pre-reaction solution to 40-90° C., and continue stirring the reaction for 10-15 hours to obtain a post-reaction solution; The reaction solution was cooled to room temperature and poured into ice water, and 0.5-5 mL of hydrogen peroxide was added through the spiral tubular membrane of the membrane uniformly distributed microreactor under stirring to continue the reaction; After the solution turns golden yellow, the reaction product is obtained by filtration; The reaction product was washed with distilled water and 2-10 vol% hydrochloric acid to a pH of 6-8; The washed product was dispersed in water and ultrasonicated for 5-10 hours, and then vacuum freeze-dried to obtain graphene oxide powder.

5. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 4, characterized in that: The graphite powder is flaky graphite powder with a particle size of 100-1000 meshes, and the phosphoric acid is AR pure phosphoric acid.

6. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 5, characterized in that: The membrane uniformly distributed microreactor used for graphene oxide synthesis is a tubular membrane wound into a spiral shape with 4 turns, with a diameter of 5mm, a dispersion hole diameter of 0.1-0.5μm, an external magnetic stirring speed of 100-200rpm, and a flow rate of 0.1-1mL / min for the phosphoric acid to pass into the tubular membrane.

7. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 1, characterized in that: The synthesis of the nanoporous graphene comprises the following steps: The synthesized graphene oxide is added with water to prepare a graphene suspension of 0.5-5 g / L; 0.5-5 g / L graphene suspension and 400-800 g / L Zn(NO3)·6H2O are mixed in a membrane uniformly distributed microreactor at a volume ratio of 1:1-1:3 to obtain a mixed turbid liquid; The mixed turbid liquid is vacuum filtered to obtain a filter cake; The filter cake and the filter paper are dried at 50-70° C. and then burned, and the combustion residue is washed with HCl and deionized water to obtain nanoporous graphene.

8. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 7, characterized in that: The membrane uniformly distributed microreactor used for the nanoporous graphene synthesis is a tubular membrane wound into a spiral shape with 6 turns, with a diameter of 4mm, a dispersed pore diameter of 0.1-0.5μm, an external magnetic stirring speed of 100-200rpm, and the flow rate of the graphene suspension and Zn(NO3)·6H2O passing into the tubular membrane is 0.2-0.5mL / min.

9. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 1, characterized in that: The synthesis of the graphene oxide / nanoporous graphene / graphene oxide two-dimensional separation membrane comprises the following steps: The prepared nanoporous graphene and graphene oxide are respectively prepared into 1-5 g / L nanoporous graphene turbid solution and 0.1-0.8 g / L graphene oxide turbid solution; Using a polyethersulfone ultrafiltration membrane as a basement membrane, 1-5 mL of graphene oxide, 1-5 mL of nanoporous graphene turbid solution, and 1-5 mL of graphene oxide turbid solution are filtered through the basement membrane in a negative pressure filtration manner to obtain a loaded basement membrane; The supported substrate membrane is vacuum dried to obtain a graphene oxide membrane / nanoporous graphene membrane / graphene oxide membrane two-dimensional separation membrane.

10. The method for preparing a material for selective adsorption of iodine-131 nuclides according to claim 9, characterized in that: The vacuum drying of the loaded substrate membrane is to place the loaded substrate membrane in a vacuum drying oven and dry it at room temperature for 20-30 hours.

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