Composite membrane for separating 226Ra and 210Pb as well as preparation method and application of composite membrane

Abstract

The invention provides a composite membrane for separating 226Ra and 210Pb as well as a preparation method and application thereof, and relates to the technical field of radioactive ion extraction and separation, and the preparation method comprises the following steps: mixing polyacrylonitrile, crown ether and ionic liquid to obtain a spinning solution, and spinning the spinning solution into a membrane to obtain the composite membrane. Effective extraction and separation of 226Ra and 210Pb in the uranium ore digestion solution can be realized, so that radioactive pollution in the environment is reduced, environmental resources can be recycled, meanwhile, the preparation method is simple and low in cost, and the prepared composite membrane is non-toxic and harmless and is beneficial to industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of extraction and separation of radioactive ions, and in particular to a composite membrane for 226 Ra and 210 Pb separation and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of global nuclear power industry and the expansion of uranium mining activities, the long-term penetration of radioactive nuclides into the environment has become a global crisis. The enrichment of 238 U decay chain nuclides 226 Ra (half-life 1600 years) and 210 Pb (half-life 22.3 years) in uranium mine wastewater poses a serious threat to the ecosystem and human health, such as 226 Ra can contaminate drinking water sources through groundwater, and 210 Pb is enriched in crops after atmospheric deposition, doubling the risk of human bone tissue radioactive exposure.

[0003] However, these nuclides have irreplaceable scientific and engineering values: 226 Ra decay daughter releases a broad spectrum of gamma rays (186-1764 keV), which is the reference source for full-band calibration of high-purity germanium detectors (HPGe), and 226 Ra standard material is also an important work content in society for monitoring radium elements in drinking water; 210 Pb is a key tool for studying climate change and pollution migration through sediment dating and aerosol tracing. Therefore, realizing 226 Ra and 210 Pb efficient extraction and separation is not only an urgent need for ecological restoration, but also a strategic prerequisite for radioactive waste resource utilization.

[0004] The extraction and separation of 226 Ra and 210 Pb are quite rare. Related research is in the extraction of lithium from geothermal brine, where someone analyzed the adsorption behavior of radium isotopes and 210 Pb and other radioactive nuclides in lithium titanate oxide (LTO) particles, and found that radium isotopes and 210 Pb are all absorbed by LTO, among which 210 Pb is almost completely adsorbed, while 226 Ra and 228 Ra adsorption rates are between 50-80%, but radium isotopes and 210Pb is only simply extracted, and is not further separated and purified; in addition, in 2020, Matthew applied for an invention patent: separation of radium, lead, bismuth and thorium for medical isotope production applications, which designed multiple processes and multiple media, and the separation process is complex and tedious.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] One of the purposes of the present application is to provide a preparation method of a composite membrane for separating 226 Ra and 210 Pb, which is simple, low in cost, and the prepared composite membrane is non-toxic and harmless, and is conducive to industrial application.

[0007] The second purpose of the present application is to provide a composite membrane for separating 226 Ra and 210 Pb, which can realize effective extraction and separation of 226 Ra and 210 Pb in uranium ore digestion solution.

[0008] The third purpose of the present application is to provide an application of a composite membrane for separating 226 Ra and 210 Pb, which is conducive to reducing radioactive pollution in the environment and recycling of environmental resources.

[0009] In order to achieve the above purposes of the present application, the following technical solutions are adopted: In a first aspect, a preparation method of a composite membrane for separating 226 Ra and 210 Pb includes the following steps: Mixing polyacrylonitrile, crown ether and ionic liquid to obtain spinning solution, taking the spinning solution to spin into film to obtain the composite membrane.

[0010] Further, the solvent used in the mixing includes N,N-dimethylformamide.

[0011] Further, the crown ether includes DtBuCH18C6.

[0012] Further, the ionic liquid includes at least one of [C6mim][NTf2], [C2mim][NTf2] and [C8mim][NTf2].

[0013] Further, the amount ratio of the polyacrylonitrile, crown ether and ionic liquid is 13:5:10.

[0014] Further, the method of spinning into film includes the following steps: The spinning solution is placed in a syringe and then loaded into an electrostatic spinning machine for spinning film formation to obtain the composite film.

[0015] In a second aspect, the composite film is prepared by the preparation method of any one of the above.

[0016] Further, the composite film has 1-10 layers, preferably 8 layers.

[0017] In a third aspect, the composite film is used for separating and extracting 226 Ra and 210 Pb in a digestion solution.

[0018] Further, the digestion solution includes a uranium ore digestion solution.

[0019] Compared with the prior art, the present application has at least the following beneficial effects: The present application provides a preparation method of a composite film for separating 226 Ra and 210 Pb, which is simple, low in cost, and harmless, and is conducive to industrial application; specifically, a crown ether is used as a chelating agent, an ionic liquid is used to provide a dynamic solvation environment, and polyacrylonitrile is used as a substrate, and then spinning film formation is performed to obtain a new electrospun film material, i.e., the composite film, which can effectively extract and separate 226 Ra and 210 Pb in a uranium ore digestion solution, thereby reducing radioactive pollution in the environment and being conducive to recycling of environmental resources.

[0020] The present application provides a composite film for separating 226 Ra and 210 Pb, which can effectively extract and separate 226 Ra and 210 Pb in a uranium ore digestion solution.

[0021] The present application provides a composite film for separating 226 Ra and 210 Pb, which is conducive to reducing radioactive pollution in the environment and recycling of environmental resources. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0023] Figure 1 Synthesis flow chart of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application; Figure 2 FT-IR chart of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application; Figure 3 Thermogravimetric chart of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application; Figure 4 XRD chart of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application; Figure 5 Scanning electron microscope chart (a-d) and TEM-EDS chart (e-m) of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application before adsorbing lead and barium ions; Figure 6 Scanning electron microscope chart (a-d) and TEM-EDS chart (e-m) of Dt+C6@PAN membrane material provided for the embodiment 1 of the present application after adsorbing lead and barium ions; Figure 7 Influence chart of Dt@PAN membrane material formed by different mass of DtBuCH18C6 in the test example 1 of the present application on adsorbing lead and barium ions;

[0024] Figure 8 Influence chart of Dt+C6@PAN membrane material in the test example 1 of the present application on adsorbing lead and barium ions in different nitric acid environments; Figure 9 Influence chart of Dt+C6@PAN membrane material in the test example 2 of the present application on adsorbing lead and barium ions in different membrane layers; Figure 10 Influence chart of Dt+C6@PAN membrane material in the test example 2 of the present application on adsorbing lead and barium in the presence of competitive ions; Figure 11 Influence chart of Dt+C6@PAN membrane material in the test example 2 of the present application on adsorbing lead and barium ions at different times; Figure 12 Influence chart of Dt+C6@PAN membrane material in the test example 2 of the present application on adsorbing lead and barium ions at different initial concentrations; Figure 13 Elution flow chart of Dt+C6@PAN membrane material in the test example 2 of the present application after adsorbing lead and barium ions and recycling performance chart of the material; Figure 14 Elution flow chart of Dt+C6@PAN membrane material in the test example 2 of the present application after adsorbing 226 Raand 210 Pb radionuclides and recycling performance chart of the material; Figure 15This is a graph showing the adsorption capacity of the composite membrane for lead ions and barium ions tested in Experimental Example 3 of the present invention. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] According to a first aspect of the present invention, there is provided a 226 Ra and 210 The preparation method of the composite membrane for Pb separation comprises the following steps: Polyacrylonitrile, crown ether and ionic liquid are mixed to obtain a spinning solution, and the spinning solution is spun into a film to obtain a composite membrane.

[0027] The preparation method of the present invention is simple and low in cost. The prepared composite membrane is non-toxic and harmless, which is conducive to industrial application. Specifically, crown ether is used as a chelating agent, ionic liquid is used to provide a dynamic solvent environment, polyacrylonitrile is used as a substrate, and a new electrospun membrane material is obtained by spinning to form a membrane, which is the desired composite membrane. The composite membrane can be used for uranium ore digestion solution. 226 Ra and 210 The effective extraction and separation of Pb reduces radioactive pollution in the environment and is also conducive to the recycling of environmental resources.

[0028] In the present invention, the mixed solvent includes but is not limited to N,N-dimethylformamide; the crown ether includes but is not limited to DtBuCH18C6, that is, 4', 4'' (5'')-di-tert-butyldicyclohexyl-18-crown-6; the ionic liquid includes but is not limited to at least one of [C6mim][NTf2], [C2mim][NTf2] and [C8mim][NTf2].

[0029] In a preferred embodiment, the usage ratio of polyacrylonitrile, crown ether and ionic liquid can be 13:5:10, but is not limited thereto.

[0030] In a preferred embodiment, the method for spinning film comprises the following steps: The obtained spinning solution is placed in a syringe, and then loaded into an electrospinning machine for spinning to form a film, thereby obtaining a composite membrane.

[0031] A kind of 226 Ra and 210 A typical preparation method of a composite membrane for Pb separation comprises the following steps: (a) dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF) and stirring at 50℃ for 24h until a transparent golden yellow color is presented, to obtain a PAN solution; (b) adding DtBuCH18C6 to the obtained PAN solution and stirring at 30℃ for 48h until no white solid is presented in the solution and the solution presents a dark yellow color, to obtain a Dt@PAN solution; (c) adding [C6mim][NTf2] solution to the obtained Dt@PAN solution and stirring at 30℃ for 12h, to obtain a Dt+C6@PAN spinning solution; (d) placing the obtained Dt+C6@PAN spinning solution in a syringe and loading into an electrospinning machine for spinning into a film (nanofiber is received by aluminum foil), to obtain a film material; (e) cutting the obtained film material using a hollow metal cylinder, to obtain a finished Dt+C6@PAN film material, which is the required composite film.

[0032] According to a second aspect of the present application, a composite film prepared by the preparation method described in any one of the above is provided.

[0033] The composite film provided by the present application is used for 226 Ra and 210 Pb separation. 226 Ra and 210 Pb separation.

[0034] In the present application, the number of film layers of the composite film can be 1-10 layers, for example, can be 1 layer, 2 layers, 3 layers, 4 layers, 6 layers, 8 layers, 10 layers, and can be further preferably 8 layers.

[0035] According to a third aspect of the present application, the composite film described above is used for separating and extracting 226 Ra and 210 Pb in a digestion solution.

[0036] In the present application, the digestion solution includes but is not limited to a uranium ore digestion solution.

[0037] The application of the composite film provided by the present application for 226 Ra and 210 Pb separation is beneficial to reducing radioactive pollution in the environment and recycling environmental resources.

[0038] The present application is further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0039] Example 1

[0040] A method for 226 Raand 210 A method for preparing a composite membrane of Pb separation, see Figure 1 , comprising the following steps: (a) Weigh 65 g of polyacrylonitrile (PAN) and dissolve it in 500 ml of N, N- dimethylformamide (DMF) at 50°C, and stir thoroughly for 24 h until it turns into a transparent golden yellow color, obtaining a PAN solution; (b) Add 25 g of DtBuCH18C6 to the obtained PAN solution, and stir thoroughly at 30°C for 48 h until there is no white solid in the solution and the solution turns dark yellow, obtaining a Dt@PAN solution; (c) Add 50 ml of [C6mim][NTf2] solution to the obtained Dt@PAN solution, and stir thoroughly at 30°C for 12 h, obtaining a Dt+C6@PAN spinning solution; (d) Place the obtained Dt+C6@PAN spinning solution in a 10 ml syringe, and then load it into an electrospinning machine to spin into a film (nanofibers are received by aluminum foil), obtaining a film material; (e) Use a hollow metal cylinder with a diameter of 25 mm to cut the obtained film material, obtaining a finished Dt+C6@PAN film material, which is the desired composite membrane.

[0041] The FT-IR graph of the Dt+C6@PAN film material obtained in this example is shown in Figure 2 , the thermogravimetric graph is shown in Figure 3 , and the XRD graph is shown in Figure 4 .

[0042] Figure 2 In the FT-IR graph, the peaks at 2940 cm -1 and 2860 cm -1 correspond to the asymmetric and symmetric stretching vibrations of methyl and methylene groups, respectively; the absorption peak at 2240 cm -1 comes from the -C≡N nitrile group of PAN; the peaks at 1730 cm -1 and 1451 cm -1 are related to C=O and C-C stretching vibrations; the absorption peaks at 1370 cm -1 and 1010 cm -1 come from the C-O-C bond of the crown ether; the sharp peak at 569 cm -1 is related to the S=O oscillation of the ionic liquid, which together confirms that DtBuCH18C6 and [C6mim][NTf2] have been successfully dispersed and fixed in the PAN matrix.

[0043] Figure 3In the first stage (25 °C-230 °C), the mass of Dt+C6@PAN gradually decreased, which was attributed to the evaporation of water and DMF; in the second stage, significant weight losses were observed at 301.9 °C, 361.6 °C, and 418.8 °C due to the decomposition of the crown ether ring, ionic liquid, and PAN (-C≡N) groups; ultimately, Dt+C6@PAN lost 65.7% of its initial mass before stabilizing.

[0044] Figure 4 In the graphite, a sharp peak appears at 17.1° and a broad peak appears at 26.4°, which are related to the recrystallization of PAN chains during the spinning process. For Dt@PAN, the main peak of DtBuCH18C6 at 18.2° is retained, but the intensity is reduced, while the small peaks at 6.8° and 9.3° disappear, indicating that the crystallinity is reduced upon loading; as for Dt+C6@PAN, the characteristic peaks of PAN and [C6mim][NTf2] (12.5° and 20.1°) and the characteristic peaks of DtBuCH18C6 all disappear, indicating that the addition of crown ether and ionic liquid destroys the order of PAN chains and the two components have been uniformly dispersed in the PAN porous framework.

[0045] Figure 5 Scanning electron microscopy images (ad), particle size distribution and TEM-EDS images (em) of the Dt+C6@PAN membrane material before adsorption of lead and barium ions; Figure 6 Scanning electron microscope images (ad), particle size distribution diagram and TEM-EDS image (em) of Dt+C6@PAN membrane material after adsorbing lead and barium ions.

[0046] like Figure 5 (ac) and Figure 6 As shown in (ac), at 200×, 500× and 4000× magnifications, the fiber morphology is clearly visible and the structure shows obvious uniformity. At 500× magnification, 200 fibers were randomly selected to obtain the diameter distribution ( Figure 5 (d) and Figure 6 (d) The results show that the fiber diameter is mainly distributed in 1.07 ± 0.33 μm before adsorption, while it decreases to 0.76 ± 0.21 μm after adsorption. This change is attributed to the hydrophilicity of Dt+C6@PAN, which plays an important role in absorbing Pb 2+ and Ba 2+ It expands when the water evaporates and then shrinks. TEM-EDS spectrum ( Figure 5 (em) and Figure 6 (em)), confirming the uniform distribution of C, N, O, F, and S in the original film, and showing the adsorption of Pb²⁺ and Ba2+ Signal, which proves the success of ion capture.

[0047] Example 2

[0048] The difference between this example and Example 1 is that [C6mim][NTf2] is replaced by [C2mim][NTf2] in step (c); The remaining steps and their parameters are the same as those in Example 1, and a composite film is obtained.

[0049] Compared with Example 1, the adsorption capacity of the composite film obtained in this example for lead ions is 5.27 mg / g, and the adsorption capacity for barium ions is 2.19 mg / g.

[0050] Example 3

[0051] The difference between this example and Example 1 is that [C6mim][NTf2] is replaced by [C8mim][NTf2] in step (c); The remaining steps and their parameters are the same as those in Example 1, and a composite film is obtained.

[0052] Compared with Example 1, the adsorption capacity of the composite film obtained in this example for lead ions is 7.26 mg / g, and the adsorption capacity for barium ions is 2.37 mg / g.

[0053] Test Example 1 Explore the effect of different mass fractions of crown ether components on the adsorption of lead and barium ions by the material (Dt@PAN) Figure 7 ): In the preparation process of the material of Example 1, step (b) is specifically studied, that is, the amount of DtBuCH18C6 added is 5g, 15g, 25g, 35g and 50g respectively, and the Dt@PAN solution is electrospun into a film, which is studied in detail.

[0054] In a 1M nitric acid environment at T=298.15K and V=10ml, 10mg of five different component film materials are added to a solution with a lead and barium ion concentration of 30mg / L for adsorption experiment, and the adsorption capacity of each material is obtained, and the best ratio (wt%=5) is obtained.

[0055] According to the best mass fraction of DtBuCH18C6 being 5%, subsequent experiments are carried out under this condition Figure 8 ). The synthesized Dt+C6@PAN film material is overlapped (the number of films is 1, 2, 3, 4, 6, 8 and 10 respectively); In a 1M nitric acid environment at T=298.15K and V=10ml, the lead and barium ion concentration of the solution is 30mg / L, and the membrane operation (T=298.15K) is carried out, and then the ion concentration of the membrane after operation is measured, and the best number of membrane layers is obtained, and the number of membrane layers is 8.

[0056] Test Example 2 Two ion adsorption rate studies were conducted under different acid conditions Figure 9 ), the solution of T = 298.15 K, V = 10 ml, lead and barium ion concentration of 30 mg / L (in 0.1 M, 0.5 M, 1 M, 3 M, 5 M, 8 M nitric acid environment) was subjected to membrane (8 layer membrane) operation (T = 298.15 K), then the ion concentration of the solution after membrane operation was measured, and the best adsorption acidity (0.1 M nitric acid environment) was obtained.

[0057] Adsorption experiments were carried out using mixed solutions, in which the concentration ratio of Pb 2+ / Ba 2+ to each interferent was 1:0, 1:1, 1:5, 1:10 and 1:50. When each interferent existed alone, the adsorption efficiency of Pb²⁺ and Ba²⁺ remained basically unchanged (Pb 2+ > 95% and Ba 2+ > 70%), while the absorption rate of U, Bi and Co was below 4%, and the absorption rate of Th did not exceed 10%. In the test of coexistence of all four interferents, the adsorption efficiency of Pb 2+ remained above 95%, the adsorption efficiency of Ba 2+ slightly decreased, but still remained above 65%, and the adsorption rate of each interferent remained below 4%. These results show that even if the concentration of interferents far exceeds the concentration of Pb 2+ and Ba 2+ , Dt+C6@PAN can still maintain excellent selectivity for target ions, which highlights its strong potential in separating 226 Raand 210 Pb from ore digestion solution containing a large number of competing species.

[0058] Effect of coexisting competitive ions on the adsorption of lead and barium ions by the material Figure 10), (a): A mixed solution of lead and barium ion concentrations of 1 mg / L and uranium concentrations of 0, 1 mg / L, 5 mg / L, 10 mg / L, and 50 mg / L, respectively, was passed through the membrane at V=10 ml and T=298.15 K. The ion concentrations of the solution after passing the membrane were measured to obtain the adsorption rates of the three ions; (bd) The operation process is the same as a, and the corresponding ions are thorium, cobalt, and bismuth, respectively; (e): When the lead and barium ions are both 1 mg / L, and the four ions of uranium, thorium, cobalt, and bismuth exist at the same time (at this time, the concentrations of the four ions of uranium, thorium, cobalt, and bismuth are the same, and the ratios of the lead / barium ions are 1:1, 5:1, 10:1, and 50:1, respectively), the membrane operation is carried out at V=10 ml and T=298.15 K. The ion concentrations of the solution after passing the membrane were measured to obtain the adsorption rates of the six ions.

[0059] The adsorption kinetics were analyzed using pseudo-first-order and pseudo-second-order models. The fitting results showed that the pseudo-second-order model better described the adsorption of Pb 2+ and Ba 2+ Ion adsorption behavior (Pb 2+ : Nonlinear R 2 = 0.970, linear R 2 = 0.999; Ba 2+ : Nonlinear R 2 = 0.982, linear R 2 = 0.999), indicating that chemisorption is the main mechanism of this process.

[0060] dynamics( Figure 11 ): (a): V = 10 ml, T = 298.15K, lead ion concentration of 30 mg / L, 80 mg Dt + C6 @ PAN material was added, and points were taken at the time period of 1 3 5 10 15 20 30 40 60 80 120 180 300 540 min, and the ion concentration was measured. The data were further fitted with the kinetic model (secondary kinetics); (a): V = 10 ml, T = 298.15K, barium ion concentration of 30 mg / L, 80 mg Dt + C6 @ PAN material was added, and points were taken at the time period of 1 3 5 10 15 20 30 4060 80 120 180 300 540 min, and the ion concentration was measured. The data were further fitted with the kinetic model (secondary kinetics).

[0061] The adsorption data were fitted to the Langmuir and Freundlich models. The Langmuir model had a higher correlation coefficient (Pb 2+ : Nonlinear R 2 = 0.993, linear R2 = 0.990; Ba 2+ : Nonlinear R 2 = 0.990, linear R 2 =0.991) and a lower chi-square value (Pb 2+ : χ 2 = 0.483; Ba 2+ : χ 2 = 0.081), indicating that its fitting performance is better. The maximum adsorption capacity (Q max ) are: Pb 2+ :26.045 mg / g;Ba 2+ : 11.926 mg / g. These findings confirm that the Langmuir model is a better fit for these two ions, which means that the adsorption sites on Dt+C6@PAN are uniformly distributed, which is conducive to monolayer adsorption.

[0062] Adsorption isotherm ( Figure 12 ): (a): V = 10 ml, T = 298.15 K, the initial concentrations of lead ion solution were 10 20 30 40 50 60 80 100 150 mg / L, respectively. Adsorption experiments were carried out at t = 6 h. The lead ion content of the solution after complete adsorption was determined, and the data were further fitted to the isotherm model (chemical adsorption); (b): V = 10 ml, T = 298.15 K, the initial concentrations of barium ion solution were 10 20 30 40 50 60 80 100 150 180 mg / L, respectively. Adsorption experiments were carried out at t = 6 h. The barium ion content of the solution after complete adsorption was determined, and the data were further fitted to the isotherm model (chemical adsorption); Simulated liquid elution experiment ( Figure 13 The membrane separation system consists of a flexible tube, a peristaltic pump, and a customized membrane column. Eight membrane layers are stacked in the column and activated with 10 ml of 0.1 M nitric acid. Then, the original solution (the lead ion concentration in the solution is 10 μg / L and the barium ion concentration is 800 μg / L-2 ml) is added. The feed rate is adjusted by the pump speed to maintain 0.4 mL / min. The barium ions and lead ions are eluted with 1 M HNO3 and 0.25 M Na2H2EDTA·2H2O, respectively. Each 2 ml of eluent is collected in a centrifuge tube, and the Pb content is determined by ICP-MS. 2 + and Ba 2 + The concentration of each component was calculated and the separation curve was drawn; the experimental results showed that Ba 2+ was concentrated in 48 mL of solution (impurity Pb 2+ The content is 0.26wt%), while Pb 2+ was concentrated in another 6 mL solution (impurity Ba 2+0.39wt%).

[0063] Real feed elution experiment and material recycling experiment Figure 14 ): The membrane separation system was composed of flexible tube, peristaltic pump and custom-made membrane column; 32 layers of membrane were stacked in the column, activated with 10 ml 0.1M nitric acid, and then 2 ml of uranium ore digestion solution was added (containing 0.5 mg / L Ra and 0.5 mg / L Pb). 226 The total activity of Ra was 57.40 Bq, 210 The total activity of Pb was 15.82 Bq), the sample speed was adjusted by pump speed, and maintained at 0.4 mL / min, and 1M HNO3 and 0.25M Na2H2EDTA·2H2O were used to elute 226 Ra and 210 Pb, respectively, and 2ml of eluent was collected in a centrifuge tube; within a certain time, the total gamma decay count of each centrifuge tube was measured using a well-type high-purity germanium detector, and the recovery rate was obtained. Repetitive experiment: the above experiment was repeated 4 times, and the reuse graph was drawn in turn.

[0064] 226 Ra was concentrated in 84 mL solution ( 210 Pb activity accounted for 4.11%), 210 Pb was concentrated in another 20 mL solution ( 226 Ra activity accounted for 1.26%); 210 The regeneration rate of Pb on Dt+C6@PAN was close to 100%, and the adsorption-desorption performance did not change significantly. In contrast, 226 The adsorption efficiency of Ra decreased slightly from 70.7% to 62.6%, while its desorption efficiency remained at about 100%. These research results show that Dt+C6@PAN has good reusability under actual feed conditions, and is a promising adsorbent for separation and recovery of radionuclides.

[0065] Test Example 3 The adsorption capacity of the composite membrane obtained in Examples 1-3 for lead ions and barium ions is shown in Figure 15 The horizontal axis represents different types of ionic liquids used, from left to right: [C2mim][NTf2], [C6mim][NTf2] and [C8mim][NTf2]. From the vertical axis, it can be seen that the adsorption capacity of the composite membrane for lead ions and barium ions increases after adding each different ionic liquid, among which [C6mim][NTf2] ionic liquid has the most obvious effect.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for 226 Ra and 210 The method for preparing a composite membrane for Pb separation is characterized in that: The following steps are involved: Polyacrylonitrile, crown ether and ionic liquid are mixed to obtain a spinning solution, and the spinning solution is spun into a film to obtain the composite membrane.

2. The preparation method according to claim 1, characterized in that The solvent used in the mixing includes N,N-dimethylformamide.

3. The preparation method according to claim 1 or 2, characterized in that The crown ethers include DtBuCH18C6.

4. The preparation method according to claim 1 or 2, characterized in that The ionic liquid includes at least one of [C6mim][NTf2], [C2mim][NTf2] and [C8mim][NTf2].

5. The preparation method according to claim 1 or 2, characterized in that The usage ratio of the polyacrylonitrile, the crown ether and the ionic liquid is 13:5:

10.

6. The preparation method according to claim 1, characterized in that The spinning film forming method comprises the following steps: The spinning solution is placed in a syringe, and then loaded into an electrospinning machine for spinning to form a film, thereby obtaining the composite membrane.

7. A composite membrane prepared by the preparation method according to any one of claims 1 to 6.

8. The composite membrane according to claim 7, characterized in that The composite membrane has 1 to 10 layers, preferably 8 layers.

9. A composite membrane according to claim 7 or 8 for separation and extraction in a digestion solution 226 Ra and 210 Application of Pb.

10. The use according to claim 9, characterized in that The digestion solution includes uranium ore digestion solution.

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