Uranium extraction nanofiber membrane assembly as well as preparation method and application thereof

Abstract

The invention discloses a uranium extraction nanofiber membrane assembly as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) fixing sandwich screen cloth on a receiving roller, and depositing polyacrylonitrile nanofibers on the sandwich screen cloth through electrostatic spinning to obtain deposited screen cloth; the thickness of the polyacrylonitrile nanofibers deposited on the sandwich screen cloth is 5-35 microns; the thickness of the sandwich screen cloth is 0.5-2 cm; the sandwich screen cloth is 120-160g / m < 2 >; (2) collecting the deposited screen cloth into a roll by using a winding machine to prepare a winding assembly; (3) immersing the winding assembly into a hydroxylamine solution to obtain an amidoximation assembly; and (4) carrying out alkali treatment on the amidoximation assembly to obtain the uranium extraction nanofiber membrane assembly. By means of the preparation method, the uranium adsorption capacity of the uranium extraction nanofiber membrane assembly in the low-concentration water-based uranium solution can be improved, and the service life is long.

Description

Technical Field

[0001] The invention relates to a uranium extraction nanofiber membrane component and a preparation method and application thereof. Background Art

[0002] Nuclear energy, as an efficient energy source without greenhouse gas emissions, plays an important role. Natural uranium, as an important resource for the development of nuclear energy, is widely used in industry, agriculture, medicine and geological surveys. Uranium resources on land are limited. There are abundant uranium resources in seawater, but the content of uranium in natural seawater is extremely low, far lower than the main metal elements in natural seawater, such as sodium and magnesium. In addition, impurity ions in seawater (such as vanadate ions, iron ions, etc.) and the attachment of marine organisms will also significantly affect the adsorption process of uranyl ions. Therefore, the research and development of uranium adsorption materials is the key to extracting uranium from seawater. Summary of the invention

[0003] One object of the present invention is to provide a method for preparing a uranium extraction nanofiber membrane assembly, which can improve the uranium adsorption capacity of the uranium extraction nanofiber membrane assembly in a low-concentration aqueous uranium solution and has a long service life. Another object of the present invention is to provide a uranium extraction nanofiber membrane assembly. Another object of the present invention is to provide a use of a uranium extraction nanofiber membrane assembly.

[0004] In one aspect, the present invention provides a method for preparing a uranium extraction nanofiber assembly, comprising the following steps:

[0005] (1) fixing the sandwich mesh on a receiving roller, and depositing polyacrylonitrile nanofibers on the sandwich mesh by electrospinning to obtain a deposited mesh;

[0006] The spinning solution includes polyacrylonitrile and a solvent, the flow rate of the spinning solution is 0.3 to 2.5 mL / h, the electrostatic spinning voltage is 15 to 22 kV, and the receiving distance is 8 to 23 cm; the thickness of the polyacrylonitrile nanofibers deposited on the sandwich mesh is 5 to 35 μm; the thickness of the sandwich mesh is 0.5 to 2 cm; and the weight of the sandwich mesh per square meter is 120 to 160 g;

[0007] (2) using a winder to collect the deposited mesh into a roll to form a winding assembly;

[0008] (3) immersing the wound assembly in a hydroxylamine solution and shaking the reaction in a water bath at 50 to 80° C. for 5 to 12 hours to obtain an amine oximation assembly;

[0009] (4) placing the amine oximation component in an alkali metal hydroxide solution with a concentration of 0.005-0.04 mol / L, and treating it with alkali at 40-70° C. for 2-8 hours to obtain a uranium extraction nanofiber membrane component.

[0010] The spinning solution of the present invention comprises polyacrylonitrile and a solvent. In certain embodiments, the spinning solution consists of polyacrylonitrile and a solvent.

[0011] The solvent may be selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and acetone; preferably, the solvent is selected from one or more of N,N-dimethylformamide and acetone. In some embodiments, the solvent is N,N-dimethylformamide. In other embodiments, the solvent is a mixture of N,N-dimethylformamide and acetone. The volume ratio of N,N-dimethylformamide to acetone may be (5-11):2; preferably (7-9):2. The above solvents can dissolve polyacrylonitrile uniformly to form a uniform and stable spinning solution.

[0012] The concentration of polyacrylonitrile in the spinning solution is 0.05 to 0.3 g / mL, preferably 0.08 to 0.15 g / mL. Such a spinning solution can form polyacrylonitrile fibers of appropriate diameter, thereby improving adsorption capacity and strength.

[0013] According to the preparation method of the present invention, preferably, the solvent in the spinning solution is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and acetone, and the concentration of polyacrylonitrile in the spinning solution is 0.05-0.3 g / mL.

[0014] The flow rate of the spinning solution is 0.3 to 2.5 mL / h, preferably 0.8 to 2 mL / h, and more preferably 1 to 1.5 mL / h.

[0015] The electrospinning voltage is 15 to 22 kV, preferably 17 to 20 kV, and more preferably 18 to 19 kV.

[0016] The receiving distance is 8 to 23 cm, preferably 10 to 20 cm, and more preferably 15 to 17 cm.

[0017] The above parameters can be used to deposit a uniform and high-quality polyacrylonitrile nanofiber membrane on the sandwich mesh.

[0018] The thickness of the polyacrylonitrile nanofiber membrane deposited on the sandwich mesh is 5 to 35 μm, preferably 10 to 30 μm, and more preferably 20 to 30 μm. This enables the uranium extraction nanofiber membrane assembly to have both high uranium adsorption performance and high strength, thereby improving durability in use.

[0019] The thickness of the sandwich mesh is 0.5 to 2 cm, preferably 1 to 1.5 cm. The mesh diameter of the mesh surface layer is 1 to 3 mm. The weight of each square meter of the sandwich mesh is 120 to 160 g, preferably 130 to 140 g. Such a sandwich mesh has a good permeability, so that the uranium-containing aqueous liquid can fully contact the nanofiber membrane, and can also improve the strength of the uranium extraction nanofiber membrane assembly.

[0020] In step (2), the deposited mesh is collected into a roll by a winding machine to form a winding assembly. Preferably, the winding assembly is centered on a PE tube sealed at both ends. The PE tube can support the deposited mesh and facilitate winding and use; in addition, the PE tube has good corrosion resistance and low density and can be used in seawater for a long time.

[0021] The PE tube is alternately wound with polyacrylonitrile nanofiber membrane layers and sandwich mesh layers. The layer close to the PE tube is the polyacrylonitrile nanofiber membrane layer, and the outermost layer is the sandwich mesh layer. In this way, the sandwich mesh layer can better protect the polyacrylonitrile nanofiber membrane layer.

[0022] In step (3), the winding assembly is immersed in a hydroxylamine solution and shaken in a water bath at 50 to 80° C., preferably 60 to 70° C. for 5 to 12 hours, preferably 8 to 10 hours, to obtain an amine oximation assembly. In certain embodiments, the following step is further included: the reactant obtained by the reaction is washed with water to obtain an amine oximation assembly.

[0023] The solvent of the hydroxylamine solution is selected from one or more of water, methanol, ethanol, propanol, and isopropanol. In some embodiments, the solvent of the hydroxylamine solution is methanol. In other embodiments, the solvent of the hydroxylamine solution is methanol and water. The volume ratio of methanol to water can be 1: (0.5-3); preferably 1: (1-1.5).

[0024] The molar ratio of hydroxylamine to cyano group may be (8-12):1; preferably (10-11):1.

[0025] According to the preparation method of the present invention, preferably, in step (3), the molar ratio of hydroxylamine to cyano group is (8-12):1; and the solvent in the hydroxylamine solution is selected from one or more of water, methanol, ethanol, propanol and isopropanol.

[0026] According to the preparation method of the present invention, preferably, step (3) further comprises the following steps:

[0027] Hydroxylamine hydrochloride and an alkaline substance are reacted in a solvent to obtain a hydroxylamine solution; the alkaline substance is selected from one or more of alkali metal carbonates and alkali metal hydroxides; the mass ratio of the hydroxylamine hydrochloride to the alkaline substance is 13:(5-70).

[0028] Examples of alkali metal carbonates include, but are not limited to, potassium carbonate and sodium carbonate. Examples of alkali metal hydroxides include, but are not limited to, potassium hydroxide and sodium hydroxide.

[0029] In some embodiments, the mass ratio of hydroxylamine hydrochloride to the alkaline substance is 13:(45-60). In other embodiments, the mass ratio of hydroxylamine hydrochloride to the alkaline substance is 13:(5-10).

[0030] In step (4), the amine oximation assembly is placed in an alkali metal hydroxide solution with a concentration of 0.005-0.04 mol / L, and alkali-treated at 40-70° C. for 2-8 hours to obtain a uranium extraction nanofiber membrane assembly. Preferably, the product obtained by the alkali treatment is washed to obtain a uranium extraction nanofiber membrane assembly.

[0031] Preferably, the concentration of the alkali metal hydroxide solution is 0.01 to 0.03 mol / L; more preferably, the concentration of the alkali metal hydroxide solution is 0.02 to 0.025 mol / L. The alkali metal hydroxide may be selected from potassium hydroxide and / or sodium hydroxide.

[0032] Preferably, the alkali treatment is carried out at a temperature of 50 to 60° C. Preferably, the alkali treatment time is 4 to 5 hours.

[0033] On the other hand, the present invention provides a uranium extraction nanofiber membrane component, which is prepared by the above method.

[0034] In another aspect, the present invention provides use of the above-mentioned uranium extraction nanofiber membrane assembly in extracting uranium from water.

[0035] According to the use of the present invention, preferably, the water is selected from one or more of seawater and underground brine. The uranium extraction nanofiber membrane assembly of the present invention has high strength and uranium adsorption selectivity, and can be used as a material for adsorbing uranium from seawater or underground brine.

[0036] According to the use of the present invention, preferably, the concentration of uranium in water is 10 ppb to 10 ppm. In some embodiments, the concentration of uranium in water is 20 to 35 ppb; preferably 25 to 30 ppb. In some embodiments, the concentration of uranium in water is 1 to 5 ppm; preferably 3 to 3.3 ppm. The uranium extraction nanofiber membrane assembly of the present invention has good uranium adsorption performance in low-concentration aqueous liquids.

[0037] The uranium extraction nanofiber membrane component of the present invention has a sandwich structure. The sandwich mesh can support and protect the nanofiber membrane, and can make the nanofiber membrane evenly laid on the sandwich mesh, thereby improving the strength of the nanofiber membrane. It also has good uranium adsorption performance in low-concentration uranium-containing aqueous solutions, and has high adsorption capacity and adsorption speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of a winding assembly of the present invention.

[0039] The reference numerals are as follows:

[0040] 1-PE tube; 2-polyacrylonitrile nanofiber membrane layer; 3-sandwich mesh layer. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0042] Embodiment 1-2

[0043] (1) 1 g of polyacrylonitrile is dissolved in 10 mL of solvent A to obtain a spinning solution. A sandwich mesh is fixed on a receiving roller, and polyacrylonitrile nanofibers are deposited on the sandwich mesh by electrospinning to obtain a deposited mesh.

[0044] The flow rate of the spinning solution was 1 mL / h, the electrospinning voltage was 18 kV, and the receiving distance was 15 cm.

[0045] The thickness of the sandwich mesh is 1 cm, the weight of each square meter of the sandwich mesh is 140 g, and the mesh diameter of the mesh surface layer is 1 to 3 mm.

[0046] (2) The deposited mesh is collected into a roll using a winder to form a winding assembly. The structure of the winding assembly is as follows: Figure 1 The center of the winding assembly is a PE tube 1 sealed at both ends; polyacrylonitrile nanofiber membrane layers 2 and sandwich mesh layers 3 are alternately wound outside the PE tube 1; the layer close to the PE tube is the polyacrylonitrile nanofiber membrane layer 2, and the outermost layer is the sandwich mesh layer 3.

[0047] (3) 13 g of hydroxylamine hydrochloride and an alkaline substance are reacted in solvent B to obtain a hydroxylamine solution. The wound assembly is immersed in the hydroxylamine solution, shaken in a water bath at 70° C. for 8 h, and then washed with deionized water until neutral to obtain an amine oximation assembly; wherein the molar ratio of hydroxylamine to cyano group is 10:1.

[0048] (4) The amine oxime component is placed in a potassium hydroxide solution with a concentration of 0.02 mol / L, treated with alkali at 50° C. for 5 h, and then washed with deionized water until neutral to obtain a uranium extraction nanofiber membrane component.

[0049] The specific parameters are shown in Table 1.

[0050] Table 1

[0051]

[0052] Experimental example

[0053] 1. Adsorption performance in seawater

[0054] The uranium extraction nanofiber membrane assembly was placed in spiked seawater with a uranium concentration of 3.3 ppm, and then adsorbed on a shaker at a constant temperature of 25°C for 48 hours. After the adsorption was completed, the sample was dried and the uranium adsorption capacity of the uranium extraction nanofiber membrane assembly was tested by the digestion method. The results are shown in Table 2.

[0055] Table 2

[0056] Example 1 Example 2 Uranium adsorption capacity (mg U / g) 53.96 61.2

[0057] 2. Adsorption performance in underground brine.

[0058] The uranium extraction nanofiber membrane assembly was placed in underground brine with a uranium concentration of 30 ppb, and then adsorbed on a shaker for 48 hours at a constant temperature of 25°C. After the adsorption, the sample was dried and the uranium adsorption capacity of the uranium extraction nanofiber membrane assembly was tested by the digestion method. The uranium adsorption capacity of the uranium extraction nanofiber membrane assembly of Example 1 was 0.993 mg U / g.

[0059] 3. Durability test

[0060] The uranium extraction nanofiber membrane components of Example 1 and Example 2 were placed in seawater to extract uranium. After one month of use, the uranium extraction nanofiber membrane components were in good shape, and the nanofiber membrane layer was not damaged.

[0061] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing a uranium extraction nanofiber membrane assembly, characterized in that: The steps include: (1) fixing the sandwich mesh on a receiving roller, and depositing polyacrylonitrile nanofibers on the sandwich mesh by electrospinning to obtain a deposited mesh; The spinning solution includes polyacrylonitrile and a solvent, the flow rate of the spinning solution is 0.3 to 2.5 mL / h, the electrostatic spinning voltage is 15 to 22 kV, and the receiving distance is 8 to 23 cm; the thickness of the polyacrylonitrile nanofibers deposited on the sandwich mesh is 5 to 35 μm; the thickness of the sandwich mesh is 0.5 to 2 cm; and the weight of the sandwich mesh per square meter is 120 to 160 g; (2) using a winder to collect the deposited mesh into a roll to form a winding assembly; (3) immersing the wound assembly in a hydroxylamine solution and shaking the solution in a water bath at 50 to 80° C. for 5 to 12 hours to obtain an amine oximation assembly; (4) placing the amine oximation component in an alkali metal hydroxide solution with a concentration of 0.005-0.04 mol / L, and treating it with alkali at 40-70° C. for 2-8 hours to obtain a uranium extraction nanofiber membrane component.

2. The preparation method according to claim 1, characterized in that: In step (3), the molar ratio of hydroxylamine to cyano group is (8-12):1; the solvent in the hydroxylamine solution is selected from one or more of water, methanol, ethanol, propanol, and isopropanol.

3. The preparation method according to claim 1, characterized in that: Step (3) further includes the following steps: Hydroxylamine hydrochloride and an alkaline substance are reacted in a solvent to obtain a hydroxylamine solution; the alkaline substance is selected from one or more of alkali metal carbonates and alkali metal hydroxides; the mass ratio of the hydroxylamine hydrochloride to the alkaline substance is 13:(5-70).

4. The preparation method according to claim 1, characterized in that: The solvent in the spinning solution is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide and acetone, and the concentration of polyacrylonitrile in the spinning solution is 0.05-0.3 g / mL.

5. The preparation method according to claim 1, characterized in that: The winding assembly is centered on a PE tube with sealed ends.

6. The preparation method according to claim 5, characterized in that: The PE tube is alternately wound with polyacrylonitrile nanofiber membrane layers and sandwich mesh layers; the layer close to the PE tube is the polyacrylonitrile nanofiber membrane layer, and the outermost layer of the winding assembly is the sandwich mesh layer.

7. A uranium extraction nanofiber membrane assembly, characterized in that: The uranium extraction nanofiber membrane assembly is prepared by the method described in any one of claims 1 to 6.

8. Use of the uranium extraction nanofiber membrane assembly according to claim 7 in extracting uranium from water.

9. The use according to claim 8, characterized in that The water is selected from one or more of seawater and underground brine.

10. The use according to claim 8, characterized in that The concentration of uranium in water is 10ppb~10ppm.

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