A flexible copper oxide / ceramic oxide nanofiber membrane and its preparation method

Abstract

This invention discloses a flexible copper oxide / ceramic oxide nanofiber membrane and its preparation method. The preparation method involves: mixing a metal source, solvent, ion dopant, and polymer spinning aid to prepare a precursor spinning solution; then using electrospinning technology and calcination treatment to prepare a flexible ceramic oxide nanofiber membrane; subjecting the obtained ceramic oxide nanofiber membrane to ion adsorption anchoring treatment by immersing the membrane in copper salt and sulfide salt solutions respectively to obtain a flexible CuS / ceramic oxide nanofiber membrane; and finally subjecting the obtained CuS / ceramic oxide nanofiber membrane to high-temperature oxidation treatment in an oxygen atmosphere to obtain a flexible copper oxide / ceramic oxide nanofiber membrane. The ion adsorption anchoring and high-temperature oxidation treatment method used in this invention can quickly and easily anchor CuO nanoparticles to the surface of flexible ceramic oxide fibers, effectively solving the current problem of CuO nanoparticles being difficult to recombine. Moreover, this method is low in cost and easy to scale up industrially.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials technology, specifically relating to a flexible copper oxide / ceramic oxide nanofiber membrane and its preparation method. Background Technology

[0002] Copper oxide (CuO), as an excellent advanced catalytic oxidation catalyst, can generate highly oxidizing reactive oxygen species by activating persulfates and bisulfates, enabling its degradation of difficult-to-treat organic pollutants or toxic substances. Currently developed CuO nanomaterials are generally in powder form, typically existing in a dispersed state in water, leading to difficulties in recycling and secondary pollution during use, significantly limiting their practical application. Electrospinning, as a novel method for preparing inorganic nanofibers, has attracted widespread attention due to its advantages such as simple processing, low spinning cost, strong technical scalability, and the ability to spin a wide variety of nanofibers. Currently, various CuO-based nanofibers have been prepared using electrospinning technology, such as hollow CuO nanofibers, CuO / SnO2 nanofibers, and p-CuO / n-ZnO core-shell nanofibers. However, currently prepared CuO-based nanofibers generally suffer from high brittleness and easy breakage, resulting in poor stability during recycling and unstable performance.

[0003] To address the aforementioned issues, Akyldiz et al. reported in Materials Science in Semiconductor Processing 2020, 109, 104919 that CuO nanoparticles were loaded onto the surface of electrospun titanium dioxide (TiO2) nanofibers using a hydrothermal method. However, the poor continuity and brittleness of the prepared TiO2 nanofibers resulted in poor mechanical properties of the composite fiber material obtained after the hydrothermal reaction. Kim et al., in Current Research in Biotechnology 2019, 1, 1–10, directly added CuO nanoparticles to a polyacrylonitrile (PAN) solution and spun them into fibers using electrospinning technology. While this method partially solved the problem of weak mechanical properties in CuO-based nanofiber materials, the organic fiber matrix exhibited poor chemical corrosion resistance and thermal stability, making it difficult to meet the requirements for use in harsh aquatic environments. Furthermore, SEM images in the article showed that a large number of CuO nanoparticles were embedded within the fiber matrix, hindering the effective exertion of the material's catalytic activity. Summary of the Invention

[0004] To address the shortcomings of current CuO-based nanofibers, such as high brittleness, easy breakage, poor structural stability, low catalyst utilization, and cumbersome processing procedures, this invention provides a flexible copper oxide / ceramic oxide nanofiber membrane and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a flexible copper oxide / ceramic oxide nanofiber membrane includes the following steps:

[0007] Step 1: Preparation of flexible ceramic oxide nanofiber membranes

[0008] The metal source, solvent, ion dopant, and polymer spinning aid are mixed and stirred evenly to obtain a precursor spinning solution. The spinning solution is spun into a precursor nanofiber membrane using electrospinning technology. The precursor fiber membrane is then calcined in an air atmosphere to obtain a ceramic oxide nanofiber membrane.

[0009] The metal source is selected from one of zirconium acetate, zirconium oxychloride octahydrate, tetrabutyl titanate, isopropyl titanate, aluminum isopropoxide, aluminum nitrate, aluminum chloride, cobalt chloride, magnesium chloride, nickel chloride, tin chloride, or magnesium acetate.

[0010] The solvent is selected from one or more of water, ethanol, isopropanol, acetone or N,N-dimethylformamide;

[0011] The ionic dopant is selected from one or more of yttrium chloride, bismuth chloride, chromium chloride, ferric chloride, zinc chloride, lanthanum nitrate, cerium nitrate, or tetraethyl orthosilicate;

[0012] The polymer spinning aid is selected from one of polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, polyethylene oxide, or polyacrylonitrile.

[0013] The mass ratio of the metal source, solvent, and polymer spinning aid is 1:(6-15):(0.001-5), and the molar ratio of the metal source to the ion dopant is 1:(0.003-0.15).

[0014] The electrospinning process parameters are as follows: spinning temperature 18-30℃, relative humidity 20-60%, injection speed 0.1-10mL / h, spray distance 10-30cm, spinning voltage 12-55kV, and the receiving electrode is a metal roller.

[0015] The calcination process parameters are as follows: gradually increasing the temperature from room temperature to 500-1100℃ at a rate of 0.5-10℃ / min, and maintaining the highest calcination temperature for 30-360 min.

[0016] Step 2: Preparation of flexible CuS / ceramic oxide nanofiber membranes

[0017] The ceramic oxide nanofiber membrane obtained in step 1 was subjected to ion adsorption anchoring treatment. First, the membrane was immersed in a copper salt solution, left to stand for 1 to 20 minutes, then removed and washed with water. Then, it was placed in a sulfide salt solution, left to stand for 1 to 20 minutes, then removed and washed with water. Finally, it was dried to obtain a flexible CuS / ceramic oxide nanofiber membrane.

[0018] The copper salt is one of copper chloride, copper nitrate, copper sulfate, and copper acetate;

[0019] The sulfide salt is one of sodium sulfide, potassium sulfide, and ammonium sulfide;

[0020] The concentration of the copper salt solution is 0.001–1 mol / L, and the concentration of the sulfide salt solution is 0.001–1 mol / L.

[0021] The drying temperature is 50–100°C;

[0022] The drying time is 30 to 360 minutes.

[0023] Step 3: Preparation of flexible CuO / ceramic oxide nanofiber membranes

[0024] The CuS / ceramic oxide nanofiber membrane obtained in step 2 was heated to a high temperature under vacuum, and then oxygen was slowly injected. High-temperature oxidation treatment was carried out under an oxygen atmosphere to obtain a flexible CuO / ceramic oxide nanofiber membrane.

[0025] The high-temperature oxidation treatment under vacuum is carried out at a temperature of 500–1100°C, an oxygen injection rate of 20–100 mL / min, and a treatment time of 0.5–5 h.

[0026] The flexible copper oxide / ceramic oxide nanofiber membrane was prepared using the above method.

[0027] The above-mentioned flexible copper oxide / ceramic oxide nanofiber membrane is used in the preparation of oxidation catalysts.

[0028] Beneficial effects:

[0029] 1. The ion adsorption anchoring method used in this invention realizes the preparation and composite of CuO nanoparticles on the surface of flexible ceramic oxide nanofibers. Compared with the existing direct spinning method, blending method, and hydrothermal method, this method can quickly and easily anchor CuO nanoparticles to the surface of flexible ceramic oxide fibers, effectively solving the current problem of CuO nanoparticles being difficult to composite. Moreover, this method is simple, low-cost, and easy to scale up for industrial application.

[0030] 2. The CuO / ceramic oxide nanofiber membrane prepared by this invention has excellent flexibility. While ensuring high catalytic oxidation activity, it effectively solves the long-standing problems of easy agglomeration, difficult recovery, and easy secondary pollution of traditional CuO nanoparticle catalysts. Attached Figure Description

[0031] Figure 1 This is a SEM image of the flexible CuO / ZrO2 nanofiber membrane in Example 1;

[0032] Figure 2 The elemental spectrum of the flexible CuO / ZrO2 nanofibers in Example 1 is shown. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the invention are within the scope of the present invention. Experimental methods and reagents not specifically described in the embodiments are performed according to conventional conditions in the art.

[0034] Example 1

[0035] The preparation method of the flexible CuO / ceramic oxide nanofiber membrane for advanced catalytic oxidation in this embodiment specifically includes the following steps:

[0036] Step 1: Preparation of flexible ceramic oxide nanofiber membranes

[0037] Zirconium acetate, water, yttrium chloride, and polyvinylpyrrolidone were mixed and stirred evenly to prepare a precursor spinning solution, wherein the mass ratio of zirconium acetate, water, and polyvinylpyrrolidone was 1:6:0.04, and the molar ratio of zirconium acetate to yttrium chloride was 1:0.01.

[0038] Subsequently, the solution was spun into a precursor nanofiber membrane using electrospinning technology; then, the precursor fiber membrane was calcined in air to obtain a ceramic oxide nanofiber membrane. The electrospinning conditions were: spinning temperature 23℃, relative humidity 35%, infusion rate 2mL / h, spray distance 15cm, spinning voltage 40kV, and the receiving electrode was a metal roller; the calcination process parameters were: gradually increasing the temperature from room temperature to 800℃ at a rate of 5℃ / min, and maintaining the highest calcination temperature for 120min.

[0039] Step 2: Preparation of flexible CuS / ceramic oxide nanofiber membranes

[0040] The ceramic oxide nanofiber membrane obtained in step 1 was subjected to ion adsorption anchoring treatment. First, the membrane was immersed in 0.01 mol / L copper nitrate solution, left to stand for 10 min, then removed and washed with water. Then, it was placed in 0.01 mol / L sodium sulfide solution, left to stand for 10 min, then removed and washed with water. Finally, it was dried at 70℃ to obtain a flexible CuS / ceramic oxide nanofiber membrane.

[0041] Step 3: Preparation of flexible CuO / ceramic oxide nanofiber membranes

[0042] The CuS / ceramic oxide nanofiber membrane obtained in step 2 was heated to 800℃ under vacuum, and then oxygen was injected at a rate of 20 mL / min for high-temperature oxidation treatment in an oxygen atmosphere for 1 h to obtain a flexible CuO / ceramic oxide nanofiber membrane. The morphology and structure of the CuO / ceramic oxide nanofibers are as follows. Figure 1 As shown, the elemental distribution on the fiber is as follows: Figure 2 As shown.

[0043] In the flexible CuO / ceramic oxide nanofiber membrane obtained by the preparation method of this invention, CuO nanoparticles are uniformly attached to the surface of the ceramic oxide nanofibers, wherein the average diameter of the ceramic oxide fibers is 294 nm, and the average particle size of the CuO nanoparticles is approximately 50 nm. 10 mg of the composite fiber membrane catalyst, by activating potassium persulfate, achieves a 92% degradation rate of 20 mL of 10 mg / L tetracycline within 40 min, and the degradation performance remains at 90% after 10 cycles.

[0044] Comparative Example 1

[0045] The difference between Comparative Example 1 and Example 1 is that: copper nitrate, polyvinylpyrrolidone, and water were mixed and stirred in a mass ratio of 1:0.9:8.1 using the direct spinning method to prepare a spinning solution, and precursor nanofibers were spun under the same spinning conditions using electrospinning technology, and then CuO nanofibers were prepared under the same calcination conditions.

[0046] The resulting copper oxide nanofiber membrane was extremely brittle and difficult to handle with tweezers. The average fiber diameter was 400 nm, and the average particle size of the copper oxide particles was 60 nm. 10 mg of CuO nanofiber catalyst, activated with potassium persulfate, achieved a 73% degradation rate of 20 mL of 10 mg / L tetracycline within 40 min. After 10 cycles, the degradation performance was reduced to 30%. A comparison with Example 1 shows that the CuO / ceramic oxide nanofiber membrane prepared using the ion adsorption anchoring method exhibits better flexibility, more effective active sites, smaller CuO nanoparticle size, higher catalytic activity, and superior catalytic performance.

[0047] Comparative Example 2

[0048] The difference between Comparative Example 2 and Example 1 is that: using a hydrothermal reaction method, copper acetate, sodium hydroxide and water were mixed and stirred in a mass ratio of 1:0.4:22.5, and the flexible ceramic oxide nanofiber membrane was placed in the mixed solution and hydrothermally reacted at 110°C for 2 hours. Then the fiber membrane was taken out and rinsed multiple times with deionized water, thereby loading CuO nanosheet structures on the surface of ceramic oxide fibers.

[0049] The average size of the final copper oxide sheet structure was 400 nm. 10 mg of CuO / ceramic oxide nanofiber catalyst, after activation with potassium persulfate, achieved an 80% degradation rate of 20 mL of 10 mg / L tetracycline within 40 min. After 10 cycles, the degradation performance of the catalyst was 40%. A comparison with Example 1 revealed that the CuO nanostructures prepared by the hydrothermal method were difficult to effectively adhere to the fiber surface, and after multiple cycles, the nanostructures loaded on the fiber surface easily detached, ultimately leading to reduced catalytic oxidation activity and decreased cycle performance.

Claims

1. A method for preparing a flexible copper oxide / ceramic oxide nanofiber membrane, characterized by: The method comprises the following steps: Step 1: preparation of a flexible ceramic oxide nanofiber membrane The metal source, solvent, ion dopant and polymer assistant are mixed, stirred uniformly to obtain a precursor spinning solution, the spinning solution is spun into a precursor nanofiber membrane by using electrospinning technology, and the precursor fiber membrane is calcined in an air atmosphere to obtain a ceramic oxide nanofiber membrane; The metal source is selected from one of zirconium acetate, zirconium oxychloride octahydrate, tetrabutyl titanate, isopropyl titanate, aluminum isopropoxide, aluminum nitrate, aluminum chloride, cobalt chloride, magnesium chloride, nickel chloride, tin chloride or magnesium acetate; The solvent is selected from one or more of water, ethanol, isopropyl alcohol, acetone or N,N-dimethylformamide; The ion dopant is selected from one or more of yttrium chloride, bismuth chloride, chromium chloride, iron chloride, zinc chloride, lanthanum nitrate, cerium nitrate or tetraethyl orthosilicate; The polymer assistant is selected from one of polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl butyral, polyethylene oxide or polyacrylonitrile; The mass ratio of the metal source, solvent and polymer assistant is 1:(6-15):(0.001-5), and the molar ratio of the metal source to the ion dopant is 1:(0.003-0.15); Step 2: preparation of a flexible CuS / ceramic oxide nanofiber membrane The ceramic oxide nanofiber membrane obtained in step 1 is subjected to ion adsorption anchoring treatment, first immersed in a copper salt solution, taken out after standing for 1-20 min and washed with water, then placed in a sulfide salt solution, taken out after standing for 1-20 min and washed with water, and then subjected to drying treatment to obtain a flexible CuS / ceramic oxide nanofiber membrane; The copper salt is one of copper chloride, copper nitrate, copper sulfate or copper acetate; The sulfide salt is one of sodium sulfide, potassium sulfide or ammonium sulfide; Step 3: preparation of a flexible copper oxide / ceramic oxide nanofiber membrane The CuS / ceramic oxide nanofiber membrane obtained in step 2 is heated in a vacuum environment, then oxygen is slowly injected, and high-temperature oxidation treatment is performed in an oxygen atmosphere to obtain a flexible copper oxide / ceramic oxide nanofiber membrane.

2. The method of claim 1, wherein: The process parameters of electrospinning in step 1 are as follows: spinning temperature 18-30℃, relative humidity 20-60%, infusion speed 0.1-10mL / h, spraying distance 10-30cm, spinning voltage 12-55kV, and the receiving electrode plate is a metal roller.

3. The method of claim 1, wherein: The process parameters of calcination in step 1 are as follows: gradually increasing from room temperature to 500-1100℃ at a speed of 0.5-10℃ / min, and maintaining at the highest calcination temperature for 30-360min.

4. The method of claim 1, wherein: The concentration of the copper salt solution in step 2 is 0.001-1mol / L, and the concentration of the sulfide salt solution is 0.001-1mol / L; The drying temperature is 50-100℃; The drying treatment time is 30-360min.

5. The method of claim 1, wherein: In step 3, the high-temperature oxidation treatment temperature in a vacuum environment is 500-1100℃, the oxygen injection rate is 20-100mL / min, and the treatment time is 0.5-5h.

6. The flexible copper oxide / ceramic oxide nanofiber membrane prepared by the method of any one of claims 1-5.

7. Use of the flexible copper oxide / ceramic oxide nanofiber membrane of claim 6 for the preparation of an oxidation catalyst.

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