A seawater uranium extraction membrane material and preparation method thereof

Abstract

The present invention relates to the field of materials for extracting uranium from seawater, and more specifically, to a membrane material for extracting uranium from seawater and a method for preparing the same. The present invention provides a membrane material for extracting uranium from seawater and a method for preparing the membrane. The method comprises synthesizing a copper pyrazole complex 1 having photocatalytic properties, adding the complex to a PAO solution, and preparing the membrane material for extracting uranium from seawater using an electrospinning method. The photocatalytic membrane prepared by the present invention can both photocatalytically reduce uranium and separate and extract uranium from reduced uranium, enabling simultaneous separation and extraction of uranium from seawater during desalination. It can be used for seawater pretreatment, saving costs.

Description

Technical Field

[0001] The present invention relates to the field of materials for extracting uranium from seawater, and in particular to a membrane material for extracting uranium from seawater and a preparation method thereof. Background Art

[0002] my country lacks uranium resources on land, but possesses vast reserves of uranium in seawater. Seawater uranium extraction is considered a key path to sustainable nuclear energy development in my country. The combined use of desalination and seawater uranium extraction can effectively reduce the costs of related equipment and power engineering, improve the efficiency of seawater uranium extraction, and advance its industrialization. First, the desalination power system can be used to increase the external migration rate during the adsorption process. Second, the desalination pretreatment system can be used to remove interfering components, indirectly improving adsorption selectivity. Third, the combined desalination and seawater uranium extraction process can reduce adsorbent investment costs. It also reduces marine biofouling, improves material recycling efficiency, and indirectly reduces manufacturing costs.

[0003] Reverse osmosis membranes in the seawater desalination process are susceptible to fouling and have a short service life. Due to the complex composition of seawater, selecting appropriate pretreatment technologies can help mitigate membrane fouling during the reverse osmosis process, reduce membrane cleaning requirements, extend membrane service life, and further reduce water production costs. Traditional pretreatment methods primarily include coagulation and sedimentation, coagulation flotation, and granular media filtration. Compared to traditional pretreatment methods, membrane filtration produces better water quality and better retention of algae and bacteria. Therefore, it is more conducive to mitigating membrane fouling in the subsequent RO process and reducing water production costs in the SWRO process.

[0004] Although seawater uranium extraction and desalination co-production have obvious advantages in adsorption efficiency and extraction cost, the traditional adsorption uranium extraction method has many problems in its application in the field of seawater desalination-seawater uranium extraction co-production.

[0005] Problem 1: Adsorption selectivity limitation.

[0006] The composition of seawater is complex, with many + , K + , Ca 2+ Mg 2+ 、Cu 2+ 、 Fe 3+ Competing ions such as ions present a significant challenge to the design and application of adsorbent materials. This issue is particularly prominent in seawater desalination-uranium extraction co-production applications. Therefore, in this process, higher requirements are placed on the selectivity of adsorbent materials.

[0007] Question 2: The core technical difficulty of photocatalytic uranium extraction from seawater is that the reduction product uranium dioxide and the adsorption material cannot be separated: Question 2: The core technical difficulty of photocatalytic uranium extraction from seawater is that the reduction product uranium dioxide and the adsorption material cannot be separated.

[0008] Numerous studies have shown that the reduction product, uranium dioxide, is unstable and easily oxidized into uranyl ions that dissolve in seawater. Due to the extremely low uranium content in seawater, the extraction process is a relatively long process. During this process, uranium dioxide separates from the catalyst and, lacking a continuous supply of photoelectrons, it further oxidizes into uranyl ions that dissolve in seawater, thereby losing its uranium extraction function. Therefore, it is necessary to continuously separate the reduction product, uranium dioxide, to prevent it from dissolving in seawater after oxidation. However, existing photocatalytic materials are mainly powder materials. After photocatalytic reduction, the insoluble uranium dioxide precipitated in the solution detaches from the surface of the material. Under the flushing and stirring of the water flow, uranium dioxide and the photocatalytic material are evenly mixed, making it difficult to separate the uranium dioxide using existing means.

[0009] How to simultaneously achieve sterilization, photocatalysis, separation and a multifunctional separation membrane with certain mechanical properties requires the addition of multiple components. However, adding multiple components to the casting liquid has different compatibilities, making it difficult to prepare a uniform casting liquid. It is also difficult to prepare a membrane with certain separation functions, and the membrane preparation process is extremely demanding. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a membrane material for extracting uranium from seawater and a preparation method thereof. The technical concept of the present invention has the following features:

[0011] In response to problem 1, the present invention modifies polyacrylonitrile by amidoximation to make it have better selective adsorption properties for uranium.

[0012] In response to question 2, the present invention uses copper pyrazole complex as the photocatalytic active ingredient. The pyrazole ring can accelerate the electron transfer rate and the photocatalytic rate. The carbon cloth has photothermal properties and can increase the reaction rate. Photocatalysis can achieve adsorption limitation and has high selectivity. At the same time, pyrazole has good antibacterial ability, which is beneficial to extend the service life of the photocatalytic film.

[0013] To achieve multiple functions, the process utilizes a synergistic approach. Copper pyrazole enhances electron transport, increasing the photocatalytic rate and simultaneously killing bacteria. It also photocatalytically reduces uranium, generating oxygen free radicals that kill bacteria. Polyacrylonitrile stabilizes the copper pyrazole, ensuring uniform distribution and trapping bacteria. Amidoximated polyacrylonitrile selectively adsorbs uranium. These synergistic effects contribute to uranium extraction by killing bacteria and consuming free radicals, which in turn deplete holes. These three components complement and interact with each other to form a cohesive whole, rather than a simple combination.

[0014] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0015] Step 1: Preparation of pyrazole and copper complex: First, completely dissolve anhydrous copper chloride (0.94 g, 7 mmol) in 40 mL of 25% concentrated ammonia. Then, completely dissolve pyrazole (1.021 g, 15 mmol) in 40 mL of 25% concentrated ammonia. Combine the two solutions with vigorous stirring. Stir the resulting dark blue suspension for 20 minutes to obtain a blue precipitate. Filter the precipitate, wash several times with 25% concentrated ammonia and deionized water, and then dry in a vacuum oven at 40°C overnight to obtain copper pyrazole (CuPz) complex 1.

[0016] Step 2: Using commercial PAN powder containing 6.9% vinyl acetate, NH2OH-HCl was dissolved in a mixed solvent consisting of ethanol and water in a volume ratio of 4:1 to prepare an NH2OH solution with a concentration of 1 g / L to 50 g / L. The pH of the NH2OH solution was adjusted to 7.0 by adding NaOH. Under a nitrogen atmosphere, an amide oxidation reaction was carried out in a 100 mL glass flask with electromagnetic stirring at a reaction temperature of 20-80°C and a reaction time of 1-24 hours. After the amide oxidation-imine reaction was completed, the resulting material was repeatedly washed with an ethanol / water mixed solvent (volume ratio of 4:1) to remove unreacted NH2OH. The washed material was vacuum dried at 20°C to obtain PAO powder 2.

[0017] Step 3: Dissolve the required amount of PAO in DMF and stir for 48 hours, disperse 1-5 wt% of CuPz powder 1 in the DMF solution at 3000 rpm, then ultrasonicate the suspension for 90 minutes and add it to the DMF solution of PAO powder 2, which is then ultrasonicated in an ultrasonic bath for 90 minutes; the prepared CuPz-PAO composite solution is forced-spun through a stainless steel needle with a diameter of 0.66 mm, and the fibers are then collected on a stainless steel drum rotating at 10 revolutions per minute; the electrospun fabric is vacuum-dried in a dryer at room temperature overnight to remove any possible residual solvent.

[0018] Technical description:

[0019] 1 Step 1: Copper pyrazole is selected as the photocatalytic active component to improve the electron transport of the separation membrane, increase the photocatalytic rate, increase the reaction rate and kill bacteria at the same time.

[0020] 2 The amide oxidation reaction in step 2 is to introduce an amidoxime group into polyacrylonitrile, which is beneficial to the adsorption of uranium.

[0021] 3. The use of different ratios in step 2 for preparing amidoximated polyacrylonitrile is to obtain amidoximated polyacrylonitrile with different grafting rates; the copper pyrazole complex added in the ratio is to photocatalytically reduce uranium and generate oxygen free radicals for sterilization. Beneficial effects

[0022] 1. The photocatalytic film prepared by the present invention can not only photocatalytically reduce uranium, but also separate the reduced uranium, and can separate and extract uranium while desalinating seawater.

[0023] 2. The photocatalytic membrane prepared by the present invention can be used as a pretreatment of seawater before reverse osmosis to extend the service life of the reverse osmosis membrane.

[0024] 3. Sterilization helps to extract uranium. At the same time, sterilization consumes free radicals and then consumes holes, which helps to extract uranium. The prepared photocatalytic film can ensure the joint production of seawater desalination and seawater uranium extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Infrared spectrum of the copper pyrazole complex prepared in Example 1.

[0026] Figure 2 : XRD pattern of the copper pyrazole complex prepared in Example 1.

[0027] Figure 3 : Schematic diagram of the synthesis of membrane materials in Example 1. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Step 1: Preparation of pyrazole and copper complex: First, completely dissolve anhydrous copper chloride (0.94 g, 7 mmol) in 40 mL of 25% concentrated ammonia. Then, completely dissolve pyrazole (1.021 g, 15 mmol) in 40 mL of 25% concentrated ammonia. Combine the two solutions with vigorous stirring. Stir the resulting dark blue suspension for 20 minutes to obtain a blue precipitate. Filter the precipitate, wash several times with 25% concentrated ammonia and deionized water, and then dry in a vacuum oven at 40°C overnight to obtain copper pyrazole (CuPz) complex 1.

[0031] Step 2: Using commercial PAN powder containing 6.9% vinyl acetate, NH2OH-HCl was dissolved in a mixed solvent consisting of ethanol and water in a volume ratio of 4:1 to prepare an NH2OH solution with a concentration of 1 g / L to 50 g / L. The pH of the NH2OH solution was adjusted to 7.0 by adding NaOH. Under a nitrogen atmosphere, an amide oxidation reaction was carried out in a 100 mL glass flask with electromagnetic stirring at a reaction temperature of 20-80°C and a reaction time of 1-24 hours. After the amide oxidation-imine reaction was completed, the resulting material was repeatedly washed with an ethanol / water mixed solvent (volume ratio of 4:1) to remove unreacted NH2OH. The washed material was vacuum dried at 20°C to obtain PAO powder 2.

[0032] Step 3: Dissolve the required amount of PAO in DMF and stir for 48 hours, disperse 1-5 wt% of CuPz powder 1 in the DMF solution at 3000 rpm, then ultrasonicate the suspension for 90 minutes and add it to the DMF solution of PAO powder 2, which is then ultrasonicated in an ultrasonic bath for 90 minutes; the prepared CuPz-PAO composite solution is forced-spun through a stainless steel needle with a diameter of 0.66 mm, and the fibers are then collected on a stainless steel drum rotating at 10 revolutions per minute; the electrospun fabric is vacuum-dried in a dryer at room temperature overnight to remove any possible residual solvent.

[0033] The seawater uranium extraction membrane material prepared in this embodiment is a membrane prepared by electrospinning with polyacrylonitrile as the skeleton and copper pyrazole complex as the filler. The infrared spectrum and XRD pattern of the copper pyrazole complex are shown as follows: Figure 1 and Figure 2 The synthesis diagram of the seawater uranium extraction membrane prepared in this example is shown in Figure 3 shown.

[0034] Example 2

[0035] This embodiment is basically the same as the membrane material for extracting uranium from seawater and the preparation method thereof described in Example 1, except that NH2OH-HCl is dissolved in a mixed solvent consisting of ethanol and water in a volume ratio of 4:1, and the concentration of the prepared NH2OH solution is 30 g / L.

[0036] Example 3

[0037] This embodiment is basically the same as the membrane for extracting uranium from seawater and the preparation method thereof described in Example 2, except that the reaction temperature of the amide oxidation imine reaction is 60° C. and the reaction time is 3 h.

[0038] Example 4

[0039] This embodiment is basically the same as the membrane for extracting uranium from seawater and the preparation method thereof described in Example 3, except that the amount of CuPz added in step 3 is 3 wt %.

Claims

1. A method for preparing a membrane material for extracting uranium from seawater, the method comprising the following steps: Step 1: Preparation of pyrazole and copper complex: First, completely dissolve 0.94 g of anhydrous copper chloride in 40 mL of 25% concentrated ammonia water. Then, completely dissolve 1.021 g of pyrazole in 40 mL of 25% concentrated ammonia water. Mix the two solutions with vigorous stirring. Stir the resulting dark blue suspension for 20 minutes to obtain a blue precipitate. Filter the precipitate, wash it several times with 25% concentrated ammonia water and deionized water, and then dry it in a vacuum drying oven at 40°C overnight to obtain the CuPz complex. Step 2: Using commercial PAN powder containing 6.9% vinyl acetate, NH2OH-HCl was dissolved in a mixed solvent consisting of ethanol and water in a volume ratio of 4:1 to prepare an NH2OH solution with a concentration of 1 g / L to 50 g / L. The pH of the NH2OH solution was adjusted to 7.0 by adding NaOH. Under a nitrogen atmosphere, an amide oxidation reaction was carried out in a 100 mL glass flask with electromagnetic stirring, wherein the reaction temperature was 20-80°C and the reaction time was 1-24 hours. After the amide oxidation imine reaction was completed, the obtained material was repeatedly washed with a mixed solvent of ethanol / water in a volume ratio of 4:1 to remove unreacted NH2OH. The washed material was vacuum dried at 20°C to obtain PAO powder. Step 3: Dissolve the required amount of PAO powder in DMF and stir for 48 hours, disperse 1-5 wt% of CuPz complex in the DMF solution at 3000 rpm, then sonicate the suspension for 90 minutes and add it to the DMF solution of PAO powder, which is then placed in an ultrasonic bath for 90 minutes; the prepared CuPz-PAO composite solution is forced-spun through a stainless steel needle with a diameter of 0.66 mm, and the fibers are then collected on a stainless steel drum rotating at a speed of 10 revolutions per minute; the electrospun fabric is vacuum-dried in a desiccator at room temperature overnight to remove any possible residual solvent.

2. A method for preparing a membrane material for extracting uranium from seawater as claimed in claim 1, characterized in that In step 2, NH2OH-HCl is dissolved in a mixed solvent consisting of ethanol and water in a volume ratio of 4:1 to prepare an NH2OH solution with a concentration of 30 g / L.

3. A method for preparing a membrane material for extracting uranium from seawater according to claim 1 or 2, characterized in that The reaction temperature of the amide oxidation imine reaction in step 3 is 60° C. and the reaction time is 3 h.

4. A method for preparing a membrane material for extracting uranium from seawater according to claim 1 or 2, characterized in that The amount of CuPz complex added in step 3 is 3 wt %.

5. A method for preparing a membrane material for extracting uranium from seawater as claimed in claim 3, characterized in that The amount of CuPz complex added in step 3 is 3 wt %.

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