Uranium adsorbing electrospun membrane, method of making and use thereof

Abstract

This invention discloses a uranium adsorption electrospun membrane, its preparation method, and its applications. The preparation method includes the following steps: (1) adding a solution B containing hydroxylamine hydrochloride and an alkali metal carbonate to a solution A containing polyacrylonitrile, and then stirring to obtain a reaction product; centrifuging the reaction product and taking the supernatant as the spinning solution; the mass ratio of the polyacrylonitrile to the hydroxylamine hydrochloride is 2:(2-3); (2) electrospinning the spinning solution to obtain an amoxime-modified polyacrylonitrile membrane; (3) immersing the amoxime-modified polyacrylonitrile membrane in an alkali metal hydroxide solution; then immersing the alkali-treated amoxime-modified polyacrylonitrile membrane in water to obtain a uranium adsorption electrospun membrane. The preparation method of this invention can improve the utilization rate of raw materials and improve the uranium adsorption performance of the electrospun membrane.

Description

Technical Field

[0001] This invention relates to a uranium-adsorbed electrospun membrane, its preparation method, and its applications. Background Technology

[0002] Uranium resources are of great importance to industry, agriculture, and the military, and are also a crucial foundation for the development of nuclear energy. Currently, uranium resources mainly come from terrestrial uranium mines, but my country's terrestrial uranium resources are relatively scarce, posing certain challenges to their development. Seawater contains abundant uranium resources; therefore, developing efficient and economical seawater uranium extraction methods is of great significance. Among the many seawater uranium extraction methods, adsorption methods are considered one of the more promising methods due to their good adsorption selectivity, high adsorption capacity, simple operation, and low cost. Summary of the Invention

[0003] One object of the present invention is to provide a method for preparing a uranium-adsorption electrospun membrane, which can improve the utilization rate of raw materials and enhance the uranium adsorption performance of the electrospun membrane. Another object of the present invention is to provide a uranium-adsorption electrospun membrane. A further object of the present invention is to provide an application of the uranium-adsorption electrospun membrane.

[0004] On one hand, the present invention provides a method for preparing a uranium-adsorbed electrospun membrane, comprising the following steps:

[0005] (1) Add solution B containing hydroxylamine hydrochloride and alkali metal carbonate to solution A containing polyacrylonitrile, and then stir at 60-80℃ for 40-60h to obtain the reaction product; after centrifuging the reaction product, take the supernatant as the spinning solution; the mass ratio of polyacrylonitrile to hydroxylamine hydrochloride is 2:(2-3).

[0006] (2) Electrospinning the spinning solution to obtain an aminooxime-modified polyacrylonitrile membrane; wherein the injection speed of the spinning solution is 0.5-15 mL / h, the voltage of the spinning electrode is 15-50 kV, the voltage of the receiving end is -5 to -0.5 kV or the receiving end is grounded, and the distance between the receiving end and the spinning electrode is 10-60 cm.

[0007] (3) The amoxime-treated polyacrylonitrile membrane was immersed in an alkali metal hydroxide solution with a concentration of 0.005-0.04 mol / L and reacted at 40-60℃ for 2-8 h; then the alkali-treated amoxime-treated polyacrylonitrile membrane was immersed in water to obtain a uranium adsorption electrospun membrane.

[0008] This invention first oxime-encapsulates polyacrylonitrile before spinning. Compared to spinning polyacrylonitrile first and then oxime-encapsulating the polyacrylonitrile fibers, the preparation method of this invention can improve the utilization efficiency of hydroxylamine hydrochloride and enhance the adsorption performance of electrospun membranes for uranium.

[0009] According to the preparation method of the present invention, preferably, the solvent in solution A is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran, and the solvent in solution B is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran;

[0010] In solution A, the concentration of polyacrylonitrile is 0.1–0.5 g / mL;

[0011] In solution B, the concentration of hydroxylamine hydrochloride is 0.2–0.3 g / mL.

[0012] More preferably, the solvent in solution A is N,N-dimethylformamide. More preferably, the concentration of polyacrylonitrile in solution A is 0.2–0.3 g / mL.

[0013] In some embodiments, the step of preparing solution A is also included: dissolving polyacrylonitrile in a solvent and stirring to obtain solution A.

[0014] More preferably, the solvent in solution B is N,N-dimethylformamide. More preferably, the concentration of hydroxylamine hydrochloride in solution B is 0.25–0.28 g / mL.

[0015] Preferably, the mass ratio of polyacrylonitrile to hydroxylamine hydrochloride is 2:(2.5-2.7). This reduces the amount of raw materials used and increases the uranium adsorption capacity of the electrospun membrane in seawater with low uranium concentration.

[0016] According to the preparation method of the present invention, preferably, the mass ratio of hydroxylamine hydrochloride to alkali metal carbonate is 1:(1-3); the alkali metal carbonate is selected from one or more of sodium carbonate and potassium carbonate, and the alkali metal hydroxide is selected from one or more of potassium hydroxide and sodium hydroxide.

[0017] More preferably, the mass ratio of hydroxylamine hydrochloride to alkali metal carbonate is 1:(1.5-2). More preferably, the alkali metal carbonate is potassium carbonate. The potassium carbonate is anhydrous potassium carbonate.

[0018] In some embodiments, the step of preparing solution B is also included: adding hydroxylamine hydrochloride to the solvent, stirring to dissolve the hydroxylamine hydrochloride, adding an alkali metal carbonate, and stirring at 20–38°C, preferably at 25–30°C, for 2–8 hours, preferably for 3–5 hours.

[0019] Preferably, solution B containing hydroxylamine hydrochloride and alkali metal carbonate is added to solution A containing polyacrylonitrile, and then stirred at 70-75°C for 45-50 h to obtain the reaction product.

[0020] Preferably, the reaction products are centrifuged using a centrifuge.

[0021] According to the preparation method of the present invention, preferably, pneumatically assisted electrospinning or electrospinning via wire electrodes is used. In one embodiment of the present invention, pneumatically assisted electrospinning is used.

[0022] According to the preparation method of the present invention, preferably, the injection speed of the spinning solution is 8-12 mL / L, the voltage of the spinning electrode is 15-25 kV, the voltage of the receiving end is -2 to -1 kV, and the distance between the receiving end and the spinning electrode is 40-50 cm.

[0023] According to the preparation method of the present invention, preferably, the injection speed of the spinning solution is 1-2 mL / L, the voltage of the spinning electrode is 35-40 kV, the receiving end is grounded, and the distance between the receiving end and the spinning electrode is 20-30 cm.

[0024] The spinning conditions of the present invention can produce spun fiber membranes with large specific surface area, high porosity, and high strength.

[0025] Preferably, the concentration of the alkali metal hydroxide solution is 0.01–0.02 mol / L. The alkali metal hydroxide is selected from one or more of potassium hydroxide and sodium hydroxide; potassium hydroxide is preferred.

[0026] Preferably, the amoxime-modified polyacrylonitrile membrane is reacted with an alkali metal hydroxide solution at 50–55°C for 4–5 hours.

[0027] On the other hand, the present invention provides a uranium adsorption electrospun membrane, which is prepared by the above method.

[0028] In another aspect, the present invention provides the use of the above-mentioned uranium adsorption electrospun membrane in the extraction of uranium from water.

[0029] According to the intended use of the invention, preferably, the water is selected from one or more of seawater and underground brine. Preferably, the water is seawater.

[0030] According to the application of the present invention, preferably, the concentration of uranium in the water is 0.5 to 7 ppm. More preferably, the concentration of uranium in the water is 2 to 5 ppm.

[0031] The uranium adsorbent material of the present invention has good adsorption performance for low concentrations of uranium in seawater and has a high adsorption capacity.

[0032] The preparation method of this invention can improve the utilization efficiency of raw materials and enhance the uranium adsorption performance and uranium adsorption capacity of the electrospun membrane. The fiber membrane obtained by the preparation method of this invention has a large specific surface area, high porosity, and high uranium adsorption capacity. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0034] Example 1 and Comparative Example 1

[0035] (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide and stir thoroughly until the polyacrylonitrile is completely dissolved to obtain solution A. Add hydroxylamine hydrochloride to 10mL of N,N-dimethylformamide and stir until fully dissolved. Then add anhydrous potassium carbonate and stir at 25℃ for 4h to obtain solution B.

[0036] Solution B was slowly poured into solution A and stirred at 70°C for 48 hours to obtain the reaction product. The reaction product was centrifuged and the supernatant was used as the spinning solution.

[0037] (2) The spinning solution was electrospun by pneumatic assistance to obtain an aminooxime-modified polyacrylonitrile membrane. The injection speed of the spinning solution was set to 10 mL / h, the voltage of the spinning electrode was 20 kV, the voltage of the receiving end was -1 kV, and the distance between the receiving end and the spinning electrode was 50 cm.

[0038] (3) The amoxime-treated polyacrylonitrile membrane was placed in a potassium hydroxide solution with a concentration of 0.02 mol / L and reacted at 50°C for 5 h; then the alkali-treated amoxime-treated polyacrylonitrile membrane was soaked in deionized water overnight to obtain a uranium adsorption electrospun membrane.

[0039] The amounts of hydroxylamine hydrochloride and anhydrous potassium carbonate are shown in Table 1.

[0040] Table 1

[0041] Dosage of hydroxylamine hydrochloride (g) 2.6 1.3 Dosage of anhydrous potassium carbonate (g) 5.2 2.6

[0042] Example 2

[0043] (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide and stir thoroughly until the polyacrylonitrile is completely dissolved to obtain solution A. Add 2.1g of hydroxylamine hydrochloride to 10mL of N,N-dimethylformamide and stir until fully dissolved. Then add 4.2g of anhydrous potassium carbonate and stir at 25℃ for 4h to obtain solution B.

[0044] Solution B was slowly poured into solution A and stirred at 70°C for 48 hours to obtain the reaction product. The reaction product was centrifuged and the supernatant was used as the spinning solution.

[0045] (2) The spinning solution was electrospun through a wire electrode to obtain an aminooxime-modified polyacrylonitrile membrane. The injection speed of the spinning solution was set to 1 mL / h, the voltage of the spinning electrode was 40 kV, the receiving end was grounded, and the distance between the receiving end and the spinning electrode was 20 cm.

[0046] (3) The amoxime-treated polyacrylonitrile membrane was placed in a potassium hydroxide solution with a concentration of 0.02 mol / L and reacted at 50°C for 5 h; then the alkali-treated amoxime-treated polyacrylonitrile membrane was soaked in deionized water overnight to obtain a uranium adsorption electrospun membrane.

[0047] Comparative Example 2

[0048] (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide and stir thoroughly to completely dissolve the polyacrylonitrile to obtain the spinning solution.

[0049] (2) The spinning solution is electrospun through a wire electrode to obtain a polyacrylonitrile membrane. The injection speed of the spinning solution is set to 1 mL / h, the voltage of the spinning electrode is 40 kV, the receiving end is grounded, and the distance between the receiving end and the spinning electrode is 20 cm.

[0050] (3) Add 26g of hydroxylamine hydrochloride to a mixed solution of 130mL of deionized water and 130mL of methanol, and add sodium hydroxide to adjust the pH to neutral to obtain the reaction solution for oximeation.

[0051] (4) Add the polyacrylonitrile membrane to the amoximation reaction solution and react at 70°C for 48 h to obtain the amoximated polyacrylonitrile membrane.

[0052] (5) The amoxime-treated polyacrylonitrile membrane was placed in a potassium hydroxide solution with a concentration of 0.02 mol / L and reacted at 50°C for 5 h; then the alkali-treated amoxime-treated polyacrylonitrile membrane was soaked in deionized water overnight to obtain a uranium adsorption electrospun membrane.

[0053] Experimental Example

[0054] The uranium-adsorbed electrospun membrane was placed in spiked seawater with a uranium concentration of 3.3 ppm, and then subjected to adsorption at a constant temperature of 25 °C for 48 h using a shaking incubator. After adsorption, the sample was dried, and the uranium adsorption capacity of the uranium-adsorbed electrospun membrane was tested using a digestion method. The results are shown in Table 2.

[0055] Table 2

[0056] Uranium adsorption capacity (mg U / g) 60.2 31.6 47.5 1.46

[0057] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for preparing a uranium-adsorbed electrospun membrane, characterized in that, Includes the following steps: (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide and stir thoroughly to completely dissolve the polyacrylonitrile to obtain solution A; add 2.6g of hydroxylamine hydrochloride to 10mL of N,N-dimethylformamide and stir to dissolve thoroughly, then add 5.2g of anhydrous potassium carbonate and stir at 25℃ for 4h to obtain solution B; Solution B was slowly poured into solution A and stirred at 70°C for 48 hours to obtain the reaction product. The reaction product was centrifuged and the supernatant was used as the spinning solution. (2) Electrospinning the spinning solution with pneumatic assistance to obtain an aminooxime-modified polyacrylonitrile membrane; the spinning solution injection speed is set to 10 mL / h, the spinning electrode voltage is 20 kV, the receiving voltage is -1 kV, and the distance between the receiving end and the spinning electrode is 50 cm. (3) The amoxime-treated polyacrylonitrile membrane was placed in a potassium hydroxide solution with a concentration of 0.02 mol / L and reacted at 50°C for 5 h; then the alkali-treated amoxime-treated polyacrylonitrile membrane was soaked in deionized water overnight to obtain a uranium adsorption electrospun membrane.