Spinning membranes, methods of making, uses, and methods of improving spinning membrane uranium adsorption selectivity

Abstract

The application discloses a kind of spinning membrane and its preparation method, purposes and the method for improving the uranium adsorption selectivity of spinning membrane.The preparation method includes the following steps: (1) solution A containing polyacrylonitrile is added to solution B containing free hydroxylamine;After solution A is added, under the condition that temperature is 20-40 DEG C and rotation speed is 5-45rpm, first reaction is carried out, then under the condition that temperature is 20-40 DEG C and rotation speed is 120-400rpm, second reaction is carried out, to obtain reaction product;Remove insoluble matter in reaction product, to obtain electrostatic spinning liquid;(2) electrostatic spinning liquid is electrostatically spun, to obtain amidoxime polyacrylonitrile membrane;(3) amidoxime polyacrylonitrile membrane is soaked in alkali metal hydroxide solution, then the amidoxime polyacrylonitrile membrane after alkali treatment is washed, to obtain selective uranium adsorption spinning membrane.The preparation method of the application can improve the uranium adsorption selectivity of electrostatic spinning membrane.

Description

Technical Field

[0001] This invention relates to a spun membrane, its preparation method, its uses, and a method for improving the uranium adsorption selectivity of the spun membrane. Background Technology

[0002] Uranium resources are the foundation of the nuclear energy industry, and extracting uranium from seawater is one of the effective ways to solve the uranium supply problem. Seawater contains vast reserves of uranium, sufficient to support the operation of existing nuclear reactors. However, implementing uranium extraction from seawater faces numerous challenges; for example, the uranium concentration in seawater is low; the adsorption capacity of adsorbent materials is low; and competing ions affect the adsorption effect.

[0003] Metallo-oxime groups exhibit strong adsorption properties for uranium. Electrospun fiber membrane materials possess advantages such as high specific surface area and abundant porosity. However, metallo-oxime fiber membrane materials prepared using existing electrospinning processes exhibit poor selectivity, with a large amount of vanadium adsorbed within the fiber membrane material, and the adsorption capacity for vanadium exceeding that for uranium. The large amount of vanadium adsorption occupies uranium adsorption sites, which limits the application of fiber membrane materials in seawater uranium extraction. Summary of the Invention

[0004] One object of the present invention is to provide a method for preparing a selective uranium adsorption spun membrane, which improves the selectivity of the spun membrane for uranium adsorption and reduces vanadium interference. Another object of the present invention is to provide a selective uranium adsorption spun membrane. A further object of the present invention is to provide an application of the selective uranium adsorption spun membrane. Yet another object of the present invention is to provide a method for improving the uranium adsorption selectivity of the spun membrane.

[0005] On one hand, the present invention provides a method for preparing a selective uranium adsorption spinning membrane, comprising the following steps:

[0006] (1) Add solution A containing polyacrylonitrile to solution B containing free hydroxylamine; after solution A has been added, perform a first-order reaction for 0.5 to 5 hours at a temperature of 20 to 40°C and a stirring speed of 5 to 45 rpm, and then perform a second-order reaction for 15 to 36 hours at a temperature of 20 to 40°C and a stirring speed of 120 to 400 rpm to obtain the reaction product; remove the insoluble matter from the reaction product to obtain the electrospinning solution;

[0007] (2) Electrospinning the electrospinning solution to obtain a metamine oxime-modified polyacrylonitrile membrane;

[0008] (3) The amylopyridine polyacrylonitrile membrane was immersed in an alkali metal hydroxide solution, and then the alkali-treated amylopyridine polyacrylonitrile membrane was washed with water to obtain a selective uranium adsorption spinning membrane.

[0009] This invention first oxime-modifies polyacrylonitrile before spinning, thereby improving the utilization efficiency of hydroxylamine hydrochloride. This invention also reveals that the mixing method of solutions A and B, reaction temperature, and rotation speed during the oxime-modification process significantly influence the uranium adsorption selectivity of the spun membrane. The inventors speculate that this may be because, under the reaction conditions of this invention, the product contains more chain-like oxime groups and less cyclic imide dioxime groups. Cyclic imide dioxime groups readily adsorb vanadate ions, competing with uranyl ions.

[0010] Preferably, solution A containing polyacrylonitrile is added to solution B containing free hydroxylamine at a temperature of 20–40°C; more preferably, solution A containing polyacrylonitrile is added to solution B containing free hydroxylamine at a temperature of 25–30°C. Solution A can be added to solution B dropwise.

[0011] Preferably, the first-stage reaction temperature is 25–30°C. Preferably, the first-stage reaction is carried out at a rotation speed of 15–30 rpm. Preferably, the first-stage reaction time is 1–3 h.

[0012] Preferably, the secondary reaction temperature is 25–30°C. Preferably, the secondary reaction is carried out at a rotation speed of 180–250 rpm. Preferably, the secondary reaction time is 20–30 h.

[0013] The above conditions are conducive to improving the uranium adsorption selectivity of the spinning membrane.

[0014] Insoluble matter in the reaction product can be removed by one or more of the following methods: precipitation, centrifugation, and filtration. According to one embodiment of the present invention, sedimentation is used to remove solid insoluble matter from the reaction product.

[0015] According to the preparation method of the present invention, preferably, the free hydroxylamine in solution B is obtained by reacting a hydroxylamine-containing compound with an alkaline substance; the free hydroxylamine is selected from one or more of hydroxylamine hydrochloride and hydroxylamine sulfate, and the alkaline substance is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, trimethylamine, triethylamine, and pyridine;

[0016] The mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(1.5-4), and the mass ratio of hydroxylamine-containing compound to alkaline substance is 1:(0.1-2.5).

[0017] The free hydroxylamine in solution B is obtained by reacting a hydroxylamine-containing compound with an alkaline substance. The reaction temperature can be 20–40°C; preferably 25–30°C. The reaction time can be 1–10 h; preferably 3–7 h. The reaction is carried out in the presence of a solvent. Preferably, the reaction is carried out under stirring. Specifically, the hydroxylamine-containing compound can be added to the solvent, and after the hydroxylamine-containing compound dissolves, an alkaline substance is added to carry out the reaction.

[0018] Polyacrylonitrile and solvent are stirred at a temperature of 60–100°C, preferably 70–90°C, to dissolve the polyacrylonitrile in the solvent, thus obtaining solution A.

[0019] Preferably, the mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(2-3); more preferably, the mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(2.5-2.8).

[0020] Preferably, the mass ratio of the hydroxylamine compound to the alkaline substance is 1:(0.5-2); more preferably, the mass ratio of the hydroxylamine compound to the alkaline substance is 1:(1-1.8).

[0021] According to one embodiment of the present invention, the hydroxylamine-containing compound is hydroxylamine hydrochloride, and the basic substance is an alkali metal carbonate. The alkali metal carbonate may be selected from one or more of potassium carbonate and sodium carbonate.

[0022] 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, tetrahydrofuran, acetone, trifluoroacetic acid, formic acid, methanol, and ethanol, and the solvent in solution B is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetone, trifluoroacetic acid, formic acid, methanol, and ethanol.

[0023] According to one embodiment of the present invention, the solvent in solution A is N,N-dimethylformamide, and the solvent in solution B is N,N-dimethylformamide.

[0024] According to the preparation method of the present invention, preferably, based on 2g of polyacrylonitrile, the amount of solvent used in solution A is 5-30mL; based on 1g of hydroxylamine-containing compound, the amount of solvent used in solution B is 2.5-7mL.

[0025] More preferably, based on 2g of polyacrylonitrile, the amount of solvent used in solution A is 10-15mL.

[0026] More preferably, based on 1g of hydroxylamine-containing compound, the amount of solvent used in solution B is 3 to 5 mL.

[0027] According to the preparation method of the present invention, preferably, the injection speed of the spinning solution is 0.5 to 15 mL / h, the voltage of the spinning electrode is 15 to 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 to 60 cm.

[0028] Electrospinning can be performed using pneumatic assistance or via wire electrodes. According to one embodiment of the invention, pneumatic assistance is used for electrospinning.

[0029] Electrospinning is carried out under conditions of humidity ≤35%; preferably, electrospinning is carried out under conditions of humidity ≤20%.

[0030] More preferably, the spinning solution injection speed is 1-5 mL / h, the spinning electrode voltage is 17-25 kV, the receiving voltage is -2 to -1 kV, and the distance between the receiving end and the spinning electrode is 20-30 cm.

[0031] According to the preparation method of the present invention, preferably, in step (3), the concentration of the alkali metal hydroxide solution is 0.005-0.04 mol / L; the reaction temperature of the amine oxime-modified polyacrylonitrile membrane with the alkali metal hydroxide solution is 20-40℃, and the reaction time is 50-100h.

[0032] More preferably, the concentration of the alkali metal hydroxide solution is 0.01–0.03 mol / L. More preferably, the reaction temperature of the amine-oxime-treated polyacrylonitrile membrane with the alkali metal hydroxide solution is 25–30 °C, and the reaction time is 70–80 h.

[0033] Alkali metal hydroxides can be sodium hydroxide or potassium hydroxide.

[0034] On the other hand, the present invention provides a selective uranium adsorption spinning membrane, which is prepared by the above method.

[0035] In another aspect, the present invention provides the use of the above-mentioned selective uranium adsorption spinning membrane in the extraction of uranium from seawater.

[0036] The concentration of uranium in seawater can be 1 ppb to 30 ppb; preferably 2 ppb to 5 ppb. The concentration of vanadium in seawater can be 1 ppb to 30 ppb; preferably 2 ppb to 5 ppb.

[0037] The selective uranium adsorption spinning membrane of the present invention has good selective adsorption of uranium in low concentration seawater and can effectively avoid interference from vanadium in seawater.

[0038] In another aspect, the present invention provides a method for improving the uranium adsorption selectivity of spun membranes, comprising the following steps:

[0039] (1) Add solution A containing polyacrylonitrile to solution B containing free hydroxylamine; after solution A has been added, perform a first-order reaction for 0.5 to 5 hours at a temperature of 20 to 40°C and a stirring speed of 5 to 45 rpm, and then perform a second-order reaction for 15 to 36 hours at a temperature of 20 to 40°C and a stirring speed of 120 to 400 rpm to obtain the reaction product; remove the insoluble matter from the reaction product to obtain the electrospinning solution;

[0040] (2) Electrospinning the electrospinning solution to obtain a metamine oxime-modified polyacrylonitrile membrane;

[0041] (3) The amylopyridine polyacrylonitrile membrane was immersed in an alkali metal hydroxide solution, and then the alkali-treated amylopyridine polyacrylonitrile membrane was washed with water to obtain a selective uranium adsorption spinning membrane.

[0042] According to the method of the present invention, preferably, the free hydroxylamine in solution B is obtained by reacting a hydroxylamine-containing compound with an alkaline substance; the free hydroxylamine is selected from one or more of hydroxylamine hydrochloride and hydroxylamine sulfate, and the alkaline substance is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, trimethylamine, triethylamine, and pyridine;

[0043] The mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(1.5-4), and the mass ratio of hydroxylamine-containing compound to alkaline substance is 1:(0.1-2.5).

[0044] The specific steps and parameters of steps (1) to (3) are as described above and will not be repeated here.

[0045] The preparation method of the present invention can improve the utilization efficiency of raw materials, improve the uranium adsorption selectivity of the spinning membrane, and reduce the interference of vanadium in the process of extracting uranium from seawater. Detailed Implementation

[0046] 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.

[0047] Examples 1-2

[0048] (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide, and heat to 80℃ under stirring to fully dissolve the polyacrylonitrile, obtaining solution A. Add hydroxylamine hydrochloride to 10mL of N,N-dimethylformamide, and fully dissolve the hydroxylamine hydrochloride under mechanical stirring. Then add alkali metal carbonate and stir at 25℃ for 5h to obtain solution B.

[0049] Solution A was slowly added dropwise to solution B over 1 hour at 25°C. After the addition of solution A was complete, a first-order reaction was carried out at 20 rpm for 2 hours, followed by a second-order reaction at 200 rpm for 24 hours, yielding the reaction product. Both the first and second-order reactions were conducted at 25°C. The solid insoluble matter in the reaction product was precipitated by sedimentation, filtered, and collected to obtain the electrospinning solution.

[0050] (2) Under conditions of humidity ≤20%, the electrospinning solution was electrospun by pneumatic assistance to obtain a amine-oxime polyacrylonitrile membrane. The injection speed of the spinning solution was set to 1 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 25 cm.

[0051] (3) The amylopyridine polyacrylonitrile membrane was placed in a sodium hydroxide solution with a concentration of 0.02 mol / L and reacted at 25°C for 72 h; then the alkali-treated amylopyridine polyacrylonitrile membrane was rinsed in deionized water to obtain a selective uranium adsorption spinning membrane.

[0052] The dosage of hydroxylamine hydrochloride and the selection and dosage of alkali metal carbonates are shown in Table 1.

[0053] Table 1

[0054] Dosage of hydroxylamine hydrochloride (g) 2.6 2.3 Selection of alkali metal carbonates Anhydrous sodium carbonate Anhydrous potassium carbonate Amount of alkali metal carbonates (g) 4 2

[0055] Comparative Example 1

[0056] (1) Dissolve 2g of polyacrylonitrile in 10mL of N,N-dimethylformamide, and heat to 80℃ under stirring to fully dissolve the polyacrylonitrile, obtaining solution A. Add 2.6g of hydroxylamine hydrochloride to 10mL of N,N-dimethylformamide, and fully dissolve the hydroxylamine hydrochloride under mechanical stirring. Then add 4g of anhydrous sodium carbonate and stir at 25℃ for 5h to obtain solution B.

[0057] Solution B was slowly added dropwise to solution A over 1 hour at 25°C. After the addition of solution B was complete, the reaction was carried out at a reaction temperature of 70°C and a stirring speed of 200 rpm for 26 hours to obtain the reaction product. The solid insoluble matter in the reaction product was precipitated by sedimentation, filtered, and collected to obtain the electrospinning solution.

[0058] (2) Under conditions of humidity ≤20%, the electrospinning solution was electrospinned by pneumatic assistance to obtain a amine-oxime 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.

[0059] (3) The amylopyridine polyacrylonitrile membrane was placed in a sodium hydroxide solution with a concentration of 0.02 mol / L and reacted at 25°C for 72 h; then the alkali-treated amylopyridine polyacrylonitrile membrane was rinsed in deionized water to obtain a selective uranium adsorption spinning membrane.

[0060] Experimental Example

[0061] The selective uranium adsorption spun membrane was placed in natural seawater (uranium concentration 3.3 ppb, vanadium concentration 3.3 ppb) for dynamic adsorption for 60 days. After adsorption, the sample was dried, and the uranium adsorption capacity and vanadium adsorption capacity of the selective uranium adsorption spun membrane were tested using a digestion method. The results are shown in Table 2.

[0062] Table 2

[0063] Uranium adsorption capacity (mg / g) 13.2 1.72 0.43 Vanadium adsorption capacity (mg / g) 8.55 2.32 1.51

[0064] 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 selective uranium adsorption spun membrane, characterized in that, Includes the following steps: (1) Add solution A containing polyacrylonitrile dropwise to solution B containing free hydroxylamine; after solution A has been added, perform a first-order reaction for 0.5 to 5 hours at a temperature of 25 to 30°C and a stirring speed of 15 to 30 rpm, and then perform a second-order reaction for 15 to 36 hours at a temperature of 25 to 30°C and a stirring speed of 180 to 250 rpm to obtain the reaction product; remove the insoluble matter from the reaction product to obtain the electrospinning solution; (2) Electrospinning the electrospinning solution to obtain a amine-oxime-modified polyacrylonitrile membrane; (3) The amylopyridine polyacrylonitrile membrane is immersed in an alkali metal hydroxide solution, and then the alkali-treated amylopyridine polyacrylonitrile membrane is washed with water to obtain a selective uranium adsorption spinning membrane.

2. The preparation method according to claim 1, characterized in that, The free hydroxylamine in solution B is obtained by reacting a hydroxylamine-containing compound with an alkaline substance; the free hydroxylamine is selected from one or more of hydroxylamine hydrochloride and hydroxylamine sulfate, and the alkaline substance is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, trimethylamine, triethylamine, and pyridine. The mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(1.5-4), and the mass ratio of hydroxylamine-containing compound to alkaline substance is 1:(0.1-2.5).

3. The preparation method according to claim 2, characterized in that, The solvent in solution A is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetone, trifluoroacetic acid, formic acid, methanol, and ethanol. The solvent in solution B is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, acetone, trifluoroacetic acid, formic acid, methanol, and ethanol.

4. The preparation method according to claim 3, characterized in that, Based on 2g of polyacrylonitrile, the amount of solvent used in solution A is 5-30mL; based on 1g of hydroxylamine-containing compound, the amount of solvent used in solution B is 2.5-7mL.

5. The preparation method according to claim 1, characterized in that, The spinning solution injection speed is 0.5–15 mL / h, the spinning electrode voltage is 15–50 kV, the receiving end voltage is -5–-0.5 kV or the receiving end is grounded, and the distance between the receiving end and the spinning electrode is 10–60 cm.

6. The preparation method according to claim 1, characterized in that, In step (3), the concentration of the alkali metal hydroxide solution is 0.005–0.04 mol / L; the reaction temperature of the amine oxime-modified polyacrylonitrile membrane with the alkali metal hydroxide solution is 20–40 °C, and the reaction time is 50–100 h.

7. A selective uranium adsorption spinning membrane, characterized in that, The selective uranium adsorption spinning membrane is prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the selective uranium adsorption spinning membrane according to claim 7 in the extraction of uranium from seawater.

9. A method for improving the uranium adsorption selectivity of spun membranes, characterized in that, Includes the following steps: (1) Add solution A containing polyacrylonitrile dropwise to solution B containing free hydroxylamine; after solution A has been added, perform a first-order reaction for 0.5 to 5 hours at a temperature of 25 to 30°C and a stirring speed of 15 to 30 rpm, and then perform a second-order reaction for 15 to 36 hours at a temperature of 25 to 30°C and a stirring speed of 180 to 250 rpm to obtain the reaction product; remove the insoluble matter from the reaction product to obtain the electrospinning solution; (2) Electrospinning the electrospinning solution to obtain a amine-oxime-modified polyacrylonitrile membrane; (3) The amylopyridine polyacrylonitrile membrane is immersed in an alkali metal hydroxide solution, and then the alkali-treated amylopyridine polyacrylonitrile membrane is washed with water to obtain a selective uranium adsorption spinning membrane.

10. The method according to claim 9, characterized in that, The free hydroxylamine in solution B is obtained by reacting a hydroxylamine-containing compound with an alkaline substance; the free hydroxylamine is selected from one or more of hydroxylamine hydrochloride and hydroxylamine sulfate, and the alkaline substance is selected from one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, trimethylamine, triethylamine, and pyridine. The mass ratio of polyacrylonitrile to hydroxylamine-containing compound is 2:(1.5-4), and the mass ratio of hydroxylamine-containing compound to alkaline substance is 1:(0.1-2.5).