A uranium adsorbing fiber material and its preparation method and application

Abstract

The application belongs to the technical field of seawater uranium extraction, and particularly relates to a uranium adsorption fiber material and a preparation method and application thereof. The preparation method of the uranium adsorption fiber material comprises the following steps: mixing hydroxylamine hydrochloride, a carbonate, polyacrylonitrile powder and an organic solvent to perform an amidoxime reaction, so as to obtain polyacrylonitrile amidoxime spinning solution; mixing the polyacrylonitrile amidoxime spinning solution and capsaicin powder to obtain spinning solution doped with capsaicin; and performing electrostatic spinning on the spinning solution doped with capsaicin, and soaking the obtained electrostatic spinning film in lye to obtain the uranium adsorption fiber material. The uranium adsorption fiber material has improved biological adhesion resistance, and the prepared uranium adsorption fiber material has good antibacterial performance and good uranium adsorption capacity.

Description

Technical Field

[0001] This invention belongs to the field of seawater uranium extraction technology, specifically relating to a uranium adsorption fiber material, its preparation method, and its application. Background Technology

[0002] Currently, amylopectin-based adsorbents are considered the most ideal adsorbents for uranium extraction from seawater and are also the most likely to be applied in practice. To prepare fiber adsorbents containing amylopectin groups with high specific surface area and high mechanical strength, ultrafine fiber membranes can be prepared using electrospinning technology under high-voltage electrostatic traction.

[0003] However, seawater has a low uranium concentration and a high concentration of coexisting ions, making the marine environment relatively complex. In this complex environment, biofouling severely interferes with the uranium adsorption process of methine oxime-based adsorbents, reducing their uranium adsorption capacity. It also increases the complexity of the rinsing process after uranium adsorption and affects the reusability of the materials. Therefore, biofouling should be reduced or avoided. Achieving high uranium adsorption capacity in complex marine environments is one of the key challenges to overcome in seawater uranium extraction research. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a uranium adsorption fiber material, its preparation method, and its application. The uranium adsorption fiber material prepared by this invention exhibits a high uranium adsorption capacity in complex marine environments.

[0005] This invention provides a method for preparing uranium-adsorbing fiber materials, comprising the following steps: Hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder and organic solvent were mixed and subjected to a methylamine oxime reaction to obtain polyacrylonitrile methylamine oxime spinning solution; The polyacrylonitrile oxime spinning solution was mixed with capsaicin powder to obtain a capsaicin-doped spinning solution. The capsaicin-doped spinning solution was electrospun, and the resulting electrospun membrane was soaked in an alkaline solution to obtain uranium adsorption fiber material.

[0006] Preferably, the mass ratio of the capsaicin powder to the volume ratio of the polyacrylonitrile oxime spinning solution is 1~15g:100mL.

[0007] Preferably, the weight-average molecular weight of the polyacrylonitrile powder is 150,000 to 500,000.

[0008] Preferably, the mass ratio of the polyacrylonitrile powder to hydroxylamine hydrochloride is 1~3:2~3.

[0009] Preferably, the carbonate is an alkali metal carbonate, and the alkali metal carbonate is at least one of potassium carbonate and sodium carbonate.

[0010] Preferably, the mass ratio of the carbonate to hydroxylamine hydrochloride is 1~3:1~2.

[0011] Preferably, the temperature of the amylated oxime reaction is 10~60℃ and the time is 12~24h.

[0012] Preferably, the alkaline solution is at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution, and the concentration of the alkaline solution is 0.01~0.15 mol / L; the soaking temperature is 0~50℃ and the soaking time is 0.5~6h.

[0013] The present invention also provides uranium adsorption fiber materials obtained by the preparation method described in the above technical solution.

[0014] This invention also provides the application of the uranium adsorption fiber material described in the above technical solution in uranium extraction from seawater.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing uranium adsorption fiber material, comprising the following steps: mixing hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder and organic solvent to carry out a methylamine oxime reaction to obtain a polyacrylonitrile methylamine oxime spinning solution; mixing the polyacrylonitrile methylamine oxime spinning solution with capsaicin powder to obtain a capsaicin-doped spinning solution; electrospinning the capsaicin-doped spinning solution; immersing the obtained electrospun membrane in an alkaline solution to obtain uranium adsorption fiber material.

[0016] This invention prepares a PAO-LJJ electrospun membrane by doping capsaicin into a polyacrylonitrile-amine oxime electrospinning solution and then electrospinning it. The membrane is then further processed by alkali immersion to obtain PAO-LJJ uranium adsorption fiber material. This invention improves the antibacterial properties of the fiber material in real seawater and reduces the impact of biofouling on the uranium adsorption performance, thus ensuring the effective use of the amine oxime functional groups and good uranium adsorption performance in the fiber material. The uranium adsorption fiber material prepared by this invention possesses both good uranium adsorption capacity and antibacterial properties, exhibiting a high uranium adsorption capacity in complex marine environments. Detailed Implementation

[0017] This invention provides a method for preparing uranium-adsorbing fiber materials, comprising the following steps: Hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder and organic solvent were mixed and subjected to a methylamine oxime reaction to obtain polyacrylonitrile methylamine oxime spinning solution; The polyacrylonitrile oxime spinning solution was mixed with capsaicin powder to obtain a capsaicin-doped spinning solution. The capsaicin-doped spinning solution was electrospun, and the resulting electrospun membrane was soaked in an alkaline solution to obtain uranium adsorption fiber material.

[0018] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0019] This invention involves mixing hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder, and an organic solvent to undergo a metracetamation reaction, yielding a polyacrylonitrile metracetam spinning solution.

[0020] In this invention, the carbonate is preferably an alkali metal carbonate, and the alkali metal carbonate is preferably at least one of potassium carbonate and sodium carbonate; the mass ratio of the carbonate to hydroxylamine hydrochloride is preferably 1~3:1~2 (10~30:10~20), more preferably 1:1~2 (10:10~20), and even more preferably 1:1~1.5 (10:10~15), specifically 12.8:12.9. The carbonate allows hydroxylamine hydrochloride to form free hydroxylamine, ensuring that the amine oxime reaction proceeds in a neutral or weakly alkaline environment, preventing cyano hydrolysis or other side reactions. This invention selects hydroxylamine hydrochloride because it has high yield and is safe. If hydroxylamine sulfate is used, its solubility is low and the yield is low; while if hydroxylamine is used, it is too reactive and the reaction is unstable.

[0021] In this invention, the organic solvent is preferably N,N-dimethylformamide (DMF); the mass ratio of hydroxylamine hydrochloride to the volume ratio of the organic solvent is preferably 10~15g:80~120mL, more preferably 10~15g:100mL, and specifically 12.9g:100mL.

[0022] In this invention, the weight-average molecular weight of the polyacrylonitrile powder is preferably 150,000 to 500,000, specifically 150,000, 200,000, 250,000, or 500,000. The molecular weight of the polyacrylonitrile powder specified in this invention ensures that the viscosity of the prepared spinning solution is suitable, facilitating electrospinning. The mass ratio of the polyacrylonitrile powder to hydroxylamine hydrochloride is preferably 1~3:2~3 (5~15:10~15), specifically 10:12.9.

[0023] In this invention, the preferred method for mixing hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder, and organic solvent is to first stir and dissolve hydroxylamine hydrochloride and organic solvent, then add carbonate, and finally add polyacrylonitrile powder and stir until homogeneous.

[0024] In this invention, the preferred temperature for the amylopyroxylation reaction is 10-60°C, specifically 30°C, and the preferred time is 12-24 hours, specifically 24 hours. The amylopyroxylation reaction is preferably carried out under stirring, with a stirring speed preferably 50-100 rpm. During the amylopyroxylation reaction, hydroxylamine reacts with the cyano group in polyacrylonitrile to form amylopyroxyme. The reaction preferably further includes: allowing the mixture to stand for 12-24 hours, and then taking the supernatant, which is the polyacrylonitrile amylopyroxymide spinning solution (the lower layer may contain generated salts or unreacted salts).

[0025] After obtaining the polyacrylonitrile ammonium oxime spinning solution, the present invention mixes the polyacrylonitrile ammonium oxime spinning solution with capsaicin powder to obtain a capsaicin-doped spinning solution.

[0026] In this invention, the preferred mass ratio of capsaicin powder to the volume ratio of polyacrylonitrile oxime spinning solution is 1-15 g:100 mL, more preferably 2.5-5 g:100 mL, specifically 2.5 g:100 mL or 5 g:100 mL. This ratio of capsaicin powder to polyacrylonitrile oxime spinning solution results in a fiber material with a high adsorption capacity for uranium in spiked seawater, while maintaining a high uranium adsorption capacity in a real ocean environment. Capsaicin, also known as capsaicin, is a mixed alkaloid containing vanillin; it is the main source of the spiciness and medicinal properties of chili peppers, and possesses antibacterial properties. The uranium adsorption fiber material obtained by doping with capsaicin in this invention exhibits antibacterial activity against bacteria, molds, and yeasts, demonstrating broad-spectrum antibacterial activity. The mixing of the polyacrylonitrile oxime spinning solution and capsaicin powder is preferably carried out under stirring, and the capsaicin-doped spinning solution is a clear and transparent liquid.

[0027] After obtaining the capsaicin-doped spinning solution, the present invention performs electrospinning on the capsaicin-doped spinning solution, and soaks the obtained electrospinned membrane in an alkaline solution to obtain uranium adsorption fiber material.

[0028] In this invention, the electrospinning parameters include: a positive high voltage preferably of 15~21kV, specifically 18kV; a negative high voltage preferably of 0~-1.8kV, specifically -1.1kV; a feeding speed preferably of 0.03~0.1mm / min, specifically 0.06mm / min; and a receiving stroke preferably of 20~40mm, specifically 20mm. In an embodiment of this invention, specifically, 5~8mL of electrospinning solution is placed in a 10mL syringe, and the syringe is placed in the syringe holder of the electrospinning machine. The receiver of the rotating roller of the electrospinning machine is covered with a grid; the grid is made of polyester. Preferably, after electrospinning, the electrospinning film is removed from the electrospinning machine and wound up.

[0029] In this invention, the concentration of the alkaline solution is preferably 0.01~0.15 mol / L, specifically 0.05 mol / L; the alkaline solution is preferably at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution. The soaking temperature is preferably 0~50℃, specifically 30℃, and the soaking time is preferably 0.5~6h, specifically 2h. This invention uses alkaline soaking, which can activate the formed metallo-oxime groups, causing the neutral metallo-oxime groups to form oxime anions, thereby improving the chelation and adsorption capacity for uranium.

[0030] The present invention also provides uranium adsorption fiber materials obtained by the preparation method described in the above technical solution.

[0031] In this invention, the uranium adsorption fiber material has an inhibition rate of over 85% against Vibrio algae; an inhibition rate of over 51% against Escherichia coli; an inhibition rate of over 20% against Staphylococcus aureus; and a uranium adsorption capacity of over 42 mg / g in spiked seawater.

[0032] The uranium adsorption fiber material obtained by this invention is a membrane material with a thickness ranging from a few micrometers to tens of micrometers.

[0033] The uranium adsorption fiber material of the present invention exhibits significantly superior antibacterial properties and good uranium adsorption capacity compared to uranium adsorption fiber material without capsaicin doping when adsorbing uranium from real seawater.

[0034] This invention also provides the application of the uranium adsorption fiber material described in the above technical solution in uranium extraction from seawater.

[0035] To further illustrate the present invention, the following detailed description of the uranium adsorption fiber material, its preparation method, and its application, in conjunction with embodiments, is provided but should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1 The uranium adsorption fiber material is prepared according to the following steps: 1. Preparation of polyacrylonitrile-amine oxime spinning solution (PAO) Add 12.9g of hydroxylamine hydrochloride to 100mL of DMF and stir until the hydroxylamine hydrochloride is completely dissolved. Add 12.8g of potassium carbonate, then add 10g of polyacrylonitrile powder with a weight average molecular weight of 200,000 and stir until the polyacrylonitrile powder is evenly dispersed. Keep the stirring speed at 50rpm and react at 30℃ for 24h. After the reaction is completed, let it stand for 24h and take the upper layer liquid, which is the polyacrylonitrile oxime spinning solution PAO.

[0037] 2. Preparation of electrospinning solution PAO-LJJ doped with capsaicin Add 5g of capsaicin powder to 100mL of polyacrylonitrile ammonium oxime spinning solution PAO, and stir until evenly mixed to obtain a clear and transparent capsaicin-doped electrospinning solution PAO-LJJ.

[0038] 3. Preparation of PAO-LJJ electrospun membrane 5 mL of spinning solution PAO-LJJ was placed in a 10 mL syringe, and the syringe was placed in the syringe holder of the electrospinning machine. A grid was placed over the receiver of the rotating roller of the electrospinning machine. The spinning parameters of the electrospinning machine were adjusted as follows: positive high voltage of 18 kV, negative high voltage of -1.1 kV, injection speed of 0.06 mm / min, and receiving stroke of 20 mm. The PAO-LJJ electrospun membrane was obtained by spinning using the electrospinning machine.

[0039] 4. Preparation of PAO-LJJ uranium adsorption fiber material The PAO-LJJ electrospun membrane covering the grid was removed from the electrospinning machine, rolled up, and secured with cable ties. The secured PAO-LJJ electrospun membrane was then placed in a 0.05M potassium hydroxide aqueous solution and soaked at 30°C for 2 hours to obtain PAO-LJJ uranium adsorption fiber material.

[0040] Comparative Example 1 The only difference from Example 1 is that step 2 is omitted and capsaicin is not added; the remaining steps and conditions are the same.

[0041] Example 2 The only difference from Example 1 is that the weight-average molecular weight of the polyacrylonitrile powder in step 1 is 250,000, while the other steps and conditions are the same.

[0042] Example 3 The only difference from Example 1 is that the mass of capsaicin in step 2 is 2.5g, while the other steps and conditions are the same.

[0043] Performance testing The uranium adsorption fiber materials prepared in Examples 1-3 and Comparative Example 1 were subjected to uranium adsorption capacity tests, antibacterial performance (antimicrobial inhibition rate) tests, and uranium adsorption capacity tests in a real marine environment. Here, "uranium adsorption capacity" refers to the amount of uranium adsorbed per unit volume of adsorbent material, expressed in mg / g. "Antimicrobial inhibition rate" is the percentage of the difference between the number of colonies treated with the undoped capsaicin-containing uranium adsorption fiber material and the number of colonies treated with the capsaicin-containing uranium adsorption fiber material, expressed as a percentage of the number of colonies treated with the undoped capsaicin-containing uranium adsorption fiber material.

[0044] The specific testing method is as follows: (1) Uranium adsorption capacity test Uranyl carbonate was added to natural seawater to bring the uranium concentration to 3 mg / L, and the pH was adjusted to 8.1 to obtain spiked seawater. 2 L of spiked seawater was added to an Erlenmeyer flask containing 0.1 g of uranium-absorbing fiber material, and the mixture was shaken at 25 °C for 48 h for adsorption. The uranium content in the fiber material after adsorption was determined.

[0045] The uranium content was determined in accordance with HJ700-2014.

[0046] (2) Antibacterial performance test The bacteria used were Vibrio alginolyticus (marine bacteria), Escherichia coli, and Staphylococcus aureus. Vibrio alginolyticus, Escherichia coli, and Staphylococcus aureus were added to the culture medium to prepare three bacterial suspensions. PAO-LJJ uranium adsorption fiber material was added to the bacterial suspension at a dosage of 20 mg of uranium adsorption fiber material per milliliter of bacterial suspension; bacterial suspensions containing PAO uranium adsorption fiber material without capsaicin were used as controls. All six bacterial suspensions were placed in a constant temperature incubator and cultured with shaking at 37°C for 18 h. The bacterial viability was determined using the dilution plate counting method. The number of colonies formed on the plates was counted, and the inhibition rate was calculated using formula (1).

[0047] (1); In the formula: c 0 — The number of colonies on the culture plate of PAO uranium adsorption fiber material without capsaicin; c a —The number of colonies on the culture plate of bacterial solution containing uranium-adsorbing fiber material PAO-LJJ; R 1 —The antibacterial rate of uranium-adsorbed fiber materials.

[0048] (3) Uranium adsorption capacity test in real marine environment Uranium-adsorbing fiber material was placed on a sea trial platform, with a weight attached to its lower end to ensure it floated below the water surface. The membrane material was retrieved after 30 days. The uranium content in the fiber membrane material after adsorption was determined.

[0049] The uranium content was determined in accordance with HJ700-2014.

[0050] The specific parameters and test results are shown in Table 1.

[0051] Table 1. Parameters and test results of Examples 1-3 and Comparative Example 1

[0052] As shown in Table 1, when using the uranium adsorption fiber material prepared according to this invention to adsorb uranium from spiked seawater, it maintains the high adsorption capacity of the original material while also exhibiting good antibacterial properties, especially against the marine bacteria *Vibrio algae*. Furthermore, in a real marine environment (low uranium concentration, only 3.3 μg / L), the uranium adsorption fiber material prepared according to this invention still possesses a high uranium adsorption capacity, while the material in Comparative Example 1, due to the presence of bioattachment, has a significantly lower adsorption capacity than the example material.

[0053] Example 4 The only difference from Example 1 is that the mass of capsaicin in step 2 is 7.5g, while the rest of the steps and conditions are the same.

[0054] The uranium adsorption capacity of the uranium adsorption fiber material prepared in Example 4 was tested, and the result was 35.8 mg / g. The test method was the same as that in "(1) Uranium adsorption capacity test".

[0055] This invention provides a uranium-adsorbing fiber material with anti-bioattachment properties. The preparation method includes the following steps: 1) Adding polyacrylonitrile powder to a DMF solution containing dissolved hydroxylamine hydrochloride to obtain a polyacrylonitrile-amine oxime spinning solution (PAO); 2) Adding capsaicin powder to the polyacrylonitrile-amine oxime spinning solution and mixing evenly to obtain a clear and transparent capsaicin-doped electrospinning solution (PAO-LJJ); 3) Electrospinning the PAO-LJJ spinning solution using electrospinning technology to obtain a PAO-LJJ electrospinned membrane; 4) Immersing the PAO-LJJ electrospinned membrane in an alkaline solution to obtain the PAO-LJJ uranium-adsorbing fiber material. This invention improves the anti-bioattachment properties of the uranium-adsorbing fiber material. The obtained uranium-adsorbing fiber material has good antibacterial properties and good uranium adsorption capacity.

[0056] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a uranium-adsorbing fiber material, characterized in that, Includes the following steps: Hydroxylamine hydrochloride, carbonate, polyacrylonitrile powder and organic solvent were mixed and subjected to a methylamine oxime reaction to obtain polyacrylonitrile methylamine oxime spinning solution; The polyacrylonitrile oxime spinning solution was mixed with capsaicin powder to obtain a capsaicin-doped spinning solution. The capsaicin-doped spinning solution was electrospun, and the resulting electrospun membrane was soaked in an alkaline solution to obtain uranium adsorption fiber material.

2. The preparation method according to claim 1, characterized in that, The mass ratio of capsaicin powder to the volume of polyacrylonitrile oxime spinning solution is 1~15g:100mL.

3. The preparation method according to claim 1, characterized in that, The weight-average molecular weight of the polyacrylonitrile powder is 150,000 to 500,000.

4. The preparation method according to claim 1 or 3, characterized in that, The mass ratio of the polyacrylonitrile powder to hydroxylamine hydrochloride is 1~3:2~3.

5. The preparation method according to claim 1, characterized in that, The carbonate is an alkali metal carbonate, and the alkali metal carbonate is at least one of potassium carbonate and sodium carbonate.

6. The preparation method according to claim 1 or 5, characterized in that, The mass ratio of the carbonate to hydroxylamine hydrochloride is 1~3:1~2.

7. The preparation method according to claim 1, characterized in that, The oxime reaction is carried out at a temperature of 10-60°C for 12-24 hours.

8. The preparation method according to claim 1, characterized in that, The alkaline solution is at least one of sodium hydroxide aqueous solution and potassium hydroxide aqueous solution, and the concentration of the alkaline solution is 0.01~0.15 mol / L; the soaking temperature is 0~50℃ and the soaking time is 0.5~6h.

9. The uranium adsorption fiber material obtained by the preparation method according to any one of claims 1 to 8.

10. The application of the uranium adsorption fiber material according to claim 9 in uranium extraction from seawater.

Images