Preparation method of BiOCl / CA composite nanofiber material

Abstract

The application discloses a preparation method of BiOCl / CA composite nanofiber material, relates to the field of photocatalysis technology, and comprises the following steps: S10, rice straw residues are subjected to alkali treatment to obtain rice straw cellulose; S20, after the rice straw cellulose is subjected to mixed reaction with glacial acetic acid, concentrated sulfuric acid and acetic anhydride, deionized water is added for precipitation, water washing, suction filtration and freeze-drying to obtain rice straw source cellulose acetate; S30, BiOCl powder, polyvinylpyrrolidone powder and rice straw source cellulose acetate are mixed with an organic solvent to obtain a spinning solution; and S40, the spinning solution is subjected to electrostatic spinning to obtain the BiOCl / CA composite nanofiber material. The agricultural waste rice straw is separated and modified to prepare the nanofiber material with piezoelectric effect, and the photocatalytic effect of the composite material is improved.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, and in particular to a method for preparing BiOCl / CA composite nanofiber materials. Background Technology

[0002] With the rapid development of human society, energy crises and environmental pollution have become issues of concern. Semiconductor photocatalysis technology, as a green technology that uses renewable solar energy as a driving force to split water into hydrogen, reduce carbon dioxide into chemical fuels such as methane, and purify the atmosphere and water environment, has therefore received widespread attention from society.

[0003] The positively charged [Bi₂O₂] in the semiconductor photocatalytic material BiOCl 2+ Layers and negatively charged [Cl] - Layered structures readily generate built-in electric fields, making them important photocatalysts. However, the main challenges in applying photocatalysts are low electron-hole separation efficiency, hindering efficient photocatalytic reactions; and the difficulty in recycling powdered catalysts. Therefore, designing and developing a novel, highly efficient thin-film catalyst for photogenerated carrier separation is particularly urgent. Summary of the Invention

[0004] The main objective of this invention is to propose a method for preparing BiOCl / CA composite nanofiber materials. By introducing the piezoelectric effect through mechanical energy, the method effectively solves the problem of insufficient efficiency of BiOCl as a photocatalytic material in electron and hole separation, thereby enabling the prepared BiOCl / CA composite nanofiber materials to have high piezoelectric-photocatalytic performance.

[0005] To achieve the above objectives, this invention proposes a method for preparing BiOCl / CA composite nanofiber materials, the method comprising the following steps:

[0006] S10. Alkali treatment of rice straw residue yields rice straw cellulose.

[0007] S20. After mixing and reacting the rice straw cellulose with glacial acetic acid, concentrated sulfuric acid and acetic anhydride, deionized water is added to precipitate the mixture. After washing with water, filtration, and freeze-drying, rice straw-derived cellulose acetate is obtained.

[0008] S30. Mix BiOCl powder, polyvinylpyrrolidone powder, rice straw-derived cellulose acetate with an organic solvent to obtain a spinning solution;

[0009] S40. Electrospin the spinning solution to obtain BiOCl / CA composite nanofiber material.

[0010] Optionally, in step S30,

[0011] The organic solvent includes dichloromethane and glacial acetic acid, wherein the volume ratio of dichloromethane to glacial acetic acid is (2-2.5):1; and / or,

[0012] The mass ratio of BiOCl powder, rice straw-derived cellulose acetate, and polyvinylpyrrolidone powder is (0.4–6):1:0.25; and / or,

[0013] The mass concentration of rice straw-derived cellulose acetate in the spinning solution is 0.13–0.15 g / ml.

[0014] Optionally, in step S40,

[0015] The air humidity for electrospinning is 40–53%; and / or,

[0016] The air temperature for electrospinning is 27–32°C.

[0017] Optionally, in step S20,

[0018] The mass ratio of rice straw cellulose to glacial acetic acid, concentrated sulfuric acid, and acetic anhydride is 1:(8-19):(0.045-0.05):(4-5); and / or,

[0019] The mixing temperature is 50–60°C; the mixing time is 1.5–2 hours.

[0020] Optionally, step S10 includes:

[0021] S101. Mix rice straw residue with potassium hydroxide solution, filter, and adjust the pH to neutral to obtain a neutral solution;

[0022] S102. Mix the neutral solution with H2O2 solution, cool and filter, remove the filtrate, and obtain rice straw cellulose.

[0023] Optionally, in step S101,

[0024] The potassium hydroxide solution has a mass concentration of 0.04–0.05 g / ml, and 4–5 g of rice straw residue is added to every 100 ml of potassium hydroxide solution; and / or,

[0025] The mass concentration of the H2O2 solution is 0.02–0.03 g / ml; and / or,

[0026] The volume ratio of the neutral solution to the H2O2 solution is 1:(2-2.5).

[0027] Optionally, before step S10, the method further includes:

[0028] S01. Crush rice straw to obtain rice straw powder, mix the rice straw powder with an ethanol aqueous solution to obtain a premixed solution;

[0029] S02. Filter the premixed liquid, wash it, and take the filter residue to obtain rice straw residue.

[0030] Optionally, in step S01, the volume percentage of ethanol in the ethanol-water solution is 50% to 95%; and / or,

[0031] The rice straw powder has a mass concentration of 8–8.5 g / ml in the premixed solution; and / or,

[0032] The mixing temperature is 200–210°C; and / or,

[0033] The mixing time is 2 to 3 hours.

[0034] Optionally, in step S30, the BiOCl powder is prepared by the following method:

[0035] Bi(NO3)·5H2O, KCl, and deionized water were mixed, heated, cooled, washed, filtered, and dried to obtain flaky BiOCl powder.

[0036] Optionally, the molar ratio of Bi(NO3)·5H2O to KCl is 1:(1~1.1); and / or,

[0037] The heating temperature is 150–200°C; and / or,

[0038] The heating time is 18–24 hours; and / or,

[0039] The drying temperature is 80–85°C; and / or,

[0040] The drying time is 18 to 24 hours.

[0041] The technical solution provided by this invention utilizes agricultural waste rice straw, and through component separation and modification, prepares nanofiber materials with piezoelectric effects, thereby exploring the high-value utilization of agricultural waste rice straw. The flexible BiOCl / CA nanofiber material with piezoelectric-photocatalytic effects prepared by the above method has a nanofiber-like film morphology, with BiOCl sheet-like particles loaded on its fibers. It can fully utilize the piezoelectric effect to introduce mechanical and light energy from nature, improving the photocatalytic effect of the composite material. At the same time, it is easy to recycle when used as a photocatalyst. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 The X-ray diffraction pattern of the composite nanofiber material and BiOCl powder provided in Example 3 of this invention;

[0044] Figure 2 The Fourier transform infrared spectra of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 of this invention are shown below.

[0045] Figure 3 This is a scanning electron microscope image of the composite nanofiber material provided in Example 3 of the present invention;

[0046] Figure 4 The UV-Vis diffuse reflectance absorption spectra of the composite nanofiber material and BiOCl powder provided in Example 3 and Comparative Example 1 of this invention are shown below.

[0047] Figure 5 The piezoelectric output voltage signal diagrams of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 of this invention are shown.

[0048] Figure 6 The images show the piezoelectric-photocatalytic degradation effect of RhB by the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 of this invention.

[0049] Figure 7 The images show the piezoelectric-photocatalytic degradation effect of RhB by the composite nanofiber material provided in Example 3 of the present invention under vibration, light irradiation, and synergistic vibration and light irradiation conditions.

[0050] Figure 8 The photocatalytic activity diagrams of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 under vibration, light, and synergistic vibration and light conditions are shown.

[0051] Figure 9 This is a schematic diagram illustrating the influence of the piezoelectric effect of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 on the photocatalytic effect.

[0052] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] The positively charged [Bi₂O₂] in the semiconductor photocatalytic material BiOCl 2+ Layers and negatively charged [Cl] - Layered structures readily generate built-in electric fields, making them important photocatalysts. However, the main challenges in applying photocatalysts are low electron-hole separation efficiency, hindering efficient photocatalytic reactions; and the difficulty in recycling powdered catalysts. Therefore, designing and developing a novel, highly efficient thin-film catalyst for photogenerated carrier separation is particularly urgent.

[0055] The piezoelectric effect is a phenomenon where a piezoelectric material deforms under stress, generating a piezoelectric electric field. This field effectively drives electrons and holes to migrate in opposite directions, achieving efficient separation. Agricultural straw waste, a resource rich in natural high-molecular-weight cellulose, presents a significant challenge: how to prepare piezoelectric BiOCl photocatalysts from it to achieve highly efficient piezoelectric promotion of BiOCl photocatalyst activity and obtain recyclable photocatalysts is a crucial question.

[0056] In view of this, the present invention proposes a method for preparing BiOCl / CA composite nanofiber materials, aiming to provide a method for preparing nanofiber materials with piezoelectric effect from agricultural waste rice straw, so as to improve the photocatalytic effect of composite materials, and at the same time, it is easy to recycle when used as a photocatalyst.

[0057] The preparation method of BiOCl / CA composite nanofiber material provided by the present invention includes the following steps:

[0058] S10. Alkali treatment of rice straw residue yields rice straw cellulose.

[0059] S20. After mixing and reacting the rice straw cellulose with glacial acetic acid, concentrated sulfuric acid and acetic anhydride, deionized water is added to precipitate the mixture. After washing with water, filtration, and freeze-drying, rice straw-derived cellulose acetate is obtained.

[0060] S30. Mix BiOCl powder, polyvinylpyrrolidone powder (PVP), rice straw-derived cellulose acetate (CA) with an organic solvent to obtain a spinning solution;

[0061] S40. Electrospin the spinning solution to obtain BiOCl / CA composite nanofiber material.

[0062] The technical solution provided by this invention utilizes agricultural waste rice straw, and through component separation and modification, prepares nanofiber materials with piezoelectric effects, thereby exploring the high-value utilization of agricultural waste rice straw. The flexible BiOCl / CA nanofiber material with piezoelectric-photocatalytic effects prepared by the above method has a nanofiber-like film morphology, with BiOCl sheet-like particles loaded on its fibers. It can fully utilize the piezoelectric effect to introduce mechanical and light energy from nature, improving the photocatalytic effect of the composite material. At the same time, it is easy to recycle when used as a photocatalyst, making it a piezoelectric photocatalytic composite material with potential applications in agriculture and the environment.

[0063] It is understandable that before alkali treatment of rice straw residue, the rice straw needs to be processed into rice straw residue. Therefore, before step S10, the process includes: crushing the rice straw to obtain rice straw powder, mixing the rice straw powder with an ethanol aqueous solution, heating and reacting, and then repeatedly filtering and washing to obtain rice straw residue. The rice straw can be corn, wheat, sorghum, or other straw. Specifically, the rice straw can be chopped and processed in a crusher, and the resulting rice straw powder can be sieved to allow the rice straw powder to react more fully with the ethanol aqueous solution to dissolve the lignin in the rice straw. The volume percentage of ethanol in the ethanol aqueous solution is 50% to 70%. Within this range, the lignin in the rice straw can dissolve to a greater extent. Since the amount of rice straw powder relative to the ethanol aqueous solution affects the number of active groups and the concentration of reactants in the reaction system, in some embodiments of the present invention, the concentration of the rice straw powder mixed with the ethanol aqueous solution is 0.08 to 0.12 g / ml. Under these conditions, the lignin in the rice straw can dissolve to a greater extent. In specific implementations, 0.08 g to 0.12 g of rice straw powder can be mixed with 1 ml of ethanol. Preferably, when the volume percentage of ethanol in the ethanol-water solution is 70% and the concentration of the rice straw powder mixed with the ethanol-water solution is 0.08 g / ml, the amount of lignin dissolved from the rice straw is greater.

[0064] Furthermore, the processing temperature of the heating reaction of rice straw powder and ethanol aqueous solution affects the dissolution of lignin. Too low a heating temperature will result in insufficient dissolution of cellulose, while too high a heating temperature will cause cellulose degradation. Therefore, in some embodiments of the present invention, the heating temperature is 180-200°C and the heating time is 2-3 hours. Specifically, the heating temperature can be 180°C, 190°C, 200°C, etc., and the heating time can be 2 hours, 2.5 hours, 3 hours, etc. When the heating temperature is 200°C and the heating time is 3 hours, the cellulose dissolves more fully and does not degrade.

[0065] In the specific operation, rice straw powder and a certain amount of ethanol aqueous solution are poured into a reaction vessel and heated. After the reaction is completed, rice straw residue is obtained by suction filtration, and then washed with the above ethanol aqueous solution until the solution is clear and the filter cake is collected to obtain rice straw residue.

[0066] Subsequently, in step S10, rice straw residue is mixed with potassium hydroxide solution and heated, then filtered and the pH is adjusted to neutral to obtain a neutral solution. This neutral solution is then mixed with H2O2 solution and heated, cooled, and filtered to obtain rice straw cellulose. After weak alkali treatment and bleaching, hemicellulose, lignin, and other components in the rice straw residue are removed to obtain high-purity rice straw cellulose.

[0067] After treating rice straw residue with a weak alkali, it is bleached using an H2O2 solution. The potassium hydroxide solution concentration is 4%–5%, and 4–5 g of rice straw residue is added to every 100 ml of potassium hydroxide solution. The H2O2 solution concentration is 2%–3%, and the volume ratio of the neutral solution to the H2O2 solution is 1:1.

[0068] (2~2.5); High concentrations of alkali can better remove lignin. When the concentration of potassium hydroxide solution is 5%, it can remove lignin well. When the concentration of potassium hydroxide solution is less than 5%, the removal rate of lignin is low. Therefore, in some embodiments of this application, the concentration of potassium hydroxide solution is 4%~5%, and 4~5g of rice straw residue is added to every 100ml of potassium hydroxide solution for mixing.

[0069] Specifically, in some embodiments, 2-3g of rice straw residue is mixed with 50ml of 5% potassium hydroxide solution and heated at 90°C for 2 hours, then filtered and washed with deionized water until the pH is neutral to obtain a neutral solution. The neutral solution is then mixed with 100ml of 2% H2O2 solution and heated at 70°C for 3 hours, cooled and filtered to obtain rice straw cellulose.

[0070] Subsequently, in step S20, the obtained rice straw cellulose is modified by mixing and reacting it with glacial acetic acid, concentrated sulfuric acid, and acetic anhydride. The mass ratio of cellulose to glacial acetic acid is 1:(18-19); the mass ratio of cellulose to concentrated sulfuric acid is 1:(0.045-0.05); the mass ratio of cellulose to acetic anhydride is 1:(4-5); the reaction temperature is 50-60℃; and the reaction time is 1.5-2 hours. Acetylation is a reversible reaction, and under the above conditions, a large amount of the target product can be obtained. After the acetylation reaction is complete, deionized water is added for precipitation, followed by washing, filtration, and freeze-drying to obtain rice straw-derived cellulose acetate. In step S20, cellulose is acetylated to obtain rice straw-derived cellulose acetate suitable for electrospinning.

[0071] Before step S30, BiOCl powder is required. The BiOCl powder can be purchased or prepared by the following methods:

[0072] Bi(NO3)·5H2O and KCl were mixed and dissolved in deionized water, and after hydrothermal reaction, the mixture was cooled, washed, filtered, and dried to obtain flaky BiOCl powder. Bi(NO3)·5H2O provides the Bi source, and KCl provides the chlorine source. The BiOCl powder was prepared by hydrothermal reaction, wherein the molar ratio of Bi(NO3)·5H2O to KCl was 1:(1~1.1), and more specifically, the molar ratio of Bi(NO3)·5H2O to KCl was 1:1. Within this range, waste of raw materials can be avoided, and the reactants can be fully reacted. The hydrothermal temperature is 150–200℃, and the hydrothermal time is 18–24 hours. Specifically, the hydrothermal temperature can be 150℃, 160℃, 180℃, 190℃, 200℃, etc., and the hydrothermal time can be 18 hours, 20 hours, 22 hours, 24 hours, etc. Within this temperature range, the hydrothermal reaction can be more complete. After the hydrothermal reaction, the reaction product is cooled, washed, filtered, and then dried to obtain flaky BiOCl powder. In this process, the specific conditions are not limited. In some embodiments of the present invention, the high-temperature drying temperature is 80–85℃, and the high-temperature drying time is 18–24 hours, which can better dry the filtered material.

[0073] Specifically, in some embodiments, Bi(NO3)·5H2O and KCl are mixed in a 1:1 molar ratio and dissolved in deionized water. After reacting at 160°C for 24 hours, the mixture is cooled, washed, filtered, and then dried at 80°C for 24 hours to obtain flake-shaped BiOCl powder.

[0074] After obtaining rice straw-derived cellulose acetate and BiOCl powder, BiOCl powder, polyvinylpyrrolidone powder (PVP), rice straw-derived cellulose acetate, and an organic solvent were mixed to obtain a precursor spinning solution. Specifically, BiOCl powder and PVP were first mixed with the organic solvent to fully disperse the BiOCl powder. Then, rice straw-derived cellulose acetate was added. With the assistance of PVP and the solvent, the BiOCl powder could better bind with the rice straw-derived cellulose acetate, resulting in a uniform precursor spinning solution.

[0075] Furthermore, the organic solvent includes dichloromethane and glacial acetic acid, with a volume ratio of dichloromethane to glacial acetic acid of (2-2.5):1. Using a mixture of dichloromethane and glacial acetic acid as a solvent to dissolve BiOCl powder results in better solubility and promotes better binding of BiOCl powder with rice straw-derived cellulose acetate, thereby giving the resulting precursor spinning solution a better piezoelectric effect after electrospinning.

[0076] The mass-to-volume ratio of rice straw-derived cellulose acetate to organic solvent is 0.133 g / ml, meaning that for every 1 ml of organic solvent added, 0.13–0.15 g of rice straw-derived cellulose acetate is added. The mass ratio of BiOCl powder, rice straw-derived cellulose acetate, and polyvinylpyrrolidone powder is (0.4–6):1:0.25. Composite nanofiber materials prepared using the above dosage range exhibit stronger piezoelectric output voltage signals and better piezoelectric-photocatalytic effects. Specifically, when the mass ratio of BiOCl powder, rice straw-derived cellulose acetate, and polyvinylpyrrolidone powder is 2:1:0.25, the resulting composite nanofiber material exhibits even stronger piezoelectric output voltage signals and better piezoelectric-photocatalytic effects.

[0077] The present invention does not limit the reaction conditions of the above reaction. In some embodiments of the present invention, dichloromethane and glacial acetic acid are added to the sample bottle, and then PVP and BiOCl are added to the bottle and stirred at room temperature for 0.5 hours. Rice straw-derived cellulose acetate is added to the above solution and magnetically stirred for 12 hours. Under these conditions, BiOCl powder can be better combined with rice straw-derived cellulose acetate to obtain a uniform precursor spinning solution.

[0078] In step S40, the precursor spinning solution is electrospinned to prepare BiOCl / CA composite nanofiber material. The spinning voltage is 10kV positive and 5kV negative, the receiving distance is 15cm, the air humidity is 40-53%, and the air temperature is 27-32℃. Under these conditions, the obtained composite nanofiber material exhibits a stronger piezoelectric output voltage signal and better piezoelectric-photocatalytic effect.

[0079] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0080] Preparation of BiOCl powder

[0081] 2.425 g (5 mmol) Bi(NO3)·5H2O was added to the lining of a 90 ml reactor containing 45 ml of deionized water under magnetic stirring, followed by 0.373 g (5 mmol) KCl. The mixture was stirred for 0.5 h. The lining was then transferred to a hydrothermal reactor, which was placed in an oven and reacted at 160 °C for 24 h. After the reaction, the mixture was cooled, washed, filtered, and dried at 80 °C for 12 h to obtain flaky BiOCl powder.

[0082] Preparation of rice straw-derived cellulose acetate (CA) from rice straw.

[0083] Rice straw was chopped and processed in a pulverizer, and the resulting rice straw powder was sieved through a 100-mesh sieve. 5g of the sieved rice straw powder was added to a reaction vessel with 60ml of 70% ethanol-water solution and heated at 200℃ for 3 hours. After the reaction, the residue was obtained by suction filtration. The rice straw was washed with the same concentration of the above solution until the solution was clear, and the filter cake was collected. 2g of the pretreated rice straw powder was added to a beaker with 50ml of 5% potassium hydroxide solution and heated at 90℃ with stirring for 2 hours. After the reaction, the mixture was filtered and washed with deionized water until the pH was neutral. Then, it was heated and stirred at 70℃ for 3 hours with 100ml of 2% H₂O₂ solution. After cooling and suction filtration, cellulose was obtained. 1g of cellulose was placed in a three-necked flask, 17ml of glacial acetic acid was added, followed by 28μl of concentrated sulfuric acid and 4ml of acetic anhydride. An acetylation reaction was carried out at 60℃ for 1.5 hours. After the reaction time was completed, deionized water was added to the acetylated solution to precipitate the precipitate. The solution was then vacuum filtered, washed with deionized water until the pH was neutral, and finally the sample was freeze-dried to obtain rice straw-derived cellulose acetate (CA).

[0084] Example 1

[0085] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP and 0.32 g of BiOCl were added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of rice straw-derived cellulose acetate was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 48%; and the air temperature was 28 °C. A BiOCl / CA composite nanofiber material with a BiOCl content of 28.6% was obtained.

[0086] Example 2

[0087] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP and 0.8 g of BiOCl were added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of rice straw-derived cellulose acetate was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 47%; and the air temperature was 27 °C. A BiOCl / CA composite nanofiber material with a BiOCl content of 50% was obtained.

[0088] Example 3

[0089] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP and 1.6 g of BiOCl were added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of rice straw-derived cellulose acetate was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 48%; and the air temperature was 28 °C. A BiOCl / CA composite nanofiber material with a BiOCl content of 66.7% was obtained.

[0090] Example 4

[0091] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP and 3.2 g of BiOCl were added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of rice straw-derived cellulose acetate was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 50%; and the air temperature was 31 °C. This yielded a BiOCl / CA composite nanofiber material with a BiOCl content of 80%.

[0092] Example 5

[0093] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP and 4.8 g of BiOCl were added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of rice straw-derived cellulose acetate was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 50%; and the air temperature was 32 °C. A BiOCl / CA composite nanofiber material with a BiOCl content of 85.7% was obtained.

[0094] Comparative Example 1

[0095] 4 ml of dichloromethane and 2 ml of glacial acetic acid were added to a 20 ml sample vial. Then, 0.2 g of PVP was added to the vial and stirred at room temperature for 0.5 hours. Next, 0.8 g of CA was added to the solution and magnetically stirred for 12 hours to obtain a uniform, milky-white precursor spinning solution. Using an electrospinning apparatus, aluminum foil was fixed on a receiving roller as a receiving plate. The spinning voltage was 10 kV positive and 5 kV negative; the receiving distance was 15 cm; the air humidity was 48%; and the air temperature was 28 °C. Nanofiber materials were obtained.

[0096] The difference between Comparative Example 1 and Example 3 is that BiOCl was not added in Comparative Example 1.

[0097] To characterize the morphology, structure, and properties of the BiOCl / CA composite nanofiber material, the BiOCl / CA composite nanofiber material with a BiOCl content of 66.7% from Example 3 was selected for characterization.

[0098] Figure 1 The X-ray diffraction patterns of the composite nanofiber material and BiOCl powder provided in Example 3 of this invention are shown below. Figure 1 It can be seen that no other impurities were found in the BiOCl in the composite nanofiber material provided in Example 3, and all diffraction peaks corresponded to tetragonal BiOCl (PDF#06-0249), indicating that BiOCl has a good crystal structure in the BiOCl / CA composite nanofiber material.

[0099] Figure 2 The Fourier transform infrared spectra of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 of this invention are as follows: Figure 2 It can be seen that all peaks in Examples 1 to 5 and Comparative Example 1 conform to the chemical characteristic structure of CA, indicating that the CA structure was not destroyed during the recombination process.

[0100] Figure 3 This is a scanning electron microscope image of the composite nanofiber material provided in Example 3 of the present invention. Figure 3 It can be seen that the composite fiber material is composed of fibers, and BiOCl particles are attached to the fibers.

[0101] Figure 4 The images show the UV-Vis diffuse reflectance absorption spectra of the composite nanofiber material and BiOCl powder provided in Embodiment 3 and Comparative Example 1 of this invention. Figure 4 It can be seen that the composite nanofiber material obtained in Example 3 of the present invention has stronger absorption of ultraviolet and visible light.

[0102] Figure 5 The piezoelectric output voltage signal of the composite nanofiber material provided in Examples 1 to 5 and Comparative Example 1 of this invention is generated by... Figure 5 It can be seen that, compared with the composite nanofiber material obtained in Comparative Example 1, the piezoelectric output voltage signals of the composite nanofiber materials obtained in Examples 1 to 5 are weaker. Furthermore, in Examples 1 to 5, the higher the content of BiOCl in the BiOCl / CA composite nanofiber material, the lower the piezoelectricity of the resulting BiOCl / CA composite nanofiber material.

[0103] Photocatalytic effect of BiOCl / CA composite nanofiber materials

[0104] In this embodiment, the BiOCl / CA composite nanofiber materials of Examples 1-5 and Comparative Example 1 were used as catalysts, and their photocatalytic effect was tested by detecting the change in the absorbance of RhB.

[0105] A 15 mg / L RhB (Rhodamine B) solution was prepared. 50 ml of the solution was transferred to a 100 ml jacketed beaker. 50 mg of each of the BiOCl / CA composite nanofiber materials from Examples 1 to 5 and Comparative Example 6 were weighed and added to the solution. After a 0.5-hour dark adsorption reaction, a piezoelectric-photocatalytic reaction was carried out under full-spectrum conditions and magnetic stirring vibration. The piezoelectric-photocatalytic reaction time was 1 hour. Samples were taken every 10 minutes after the dark reaction and during the photocatalytic process, and the absorbance of the solution was measured.

[0106] Figure 6 and Figure 7 The image shows the effect of piezoelectric-photocatalytic degradation of RhB by composite nanofiber materials. Figure 6 The images show the piezoelectric-photocatalytic degradation effect of RhB by the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 of this invention. Figure 6It can be seen that the BiOCl / CA composite nanofiber materials prepared in Examples 1 to 5 have a significantly better piezoelectric-photocatalytic degradation effect on RhB than Comparative Example 1. Among Examples 1 to 5, the BiOCl / CA composite nanofiber material prepared in Example 3 has the best piezoelectric-photocatalytic degradation effect on RhB, indicating that the introduction of the piezoelectric effect significantly improves the photocatalytic activity, and that the higher the BiOCl content in the BiOCl / CA composite nanofiber material, the better the piezoelectric-photocatalytic effect. Figure 7 The images show the piezoelectric-photocatalytic degradation effect of RhB by the composite nanofiber material provided in Example 3 of this invention under vibration, light irradiation, and synergistic vibration and light irradiation conditions. Among them, Example 3 showed the best piezoelectric-photocatalytic degradation effect of RhB under synergistic vibration and light irradiation conditions.

[0107] Figure 8 The figures show the photocatalytic activity of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 under vibration, light, and synergistic vibration and light conditions, respectively. Figure 8 It can be seen that the photocatalytic activity of the BiOCl / CA composite nanofiber materials prepared in Examples 1 to 5 is significantly better than that of Comparative Example 1. Among Examples 1 to 5, the BiOCl / CA composite nanofiber material prepared in Example 3 has the best photocatalytic activity.

[0108] To more clearly demonstrate the impact of piezoelectricity on photocatalysis in various materials, the photocatalytic effect influence factor I is used to reflect the effect of piezoelectricity on photocatalysis, where I = piezoelectric photocatalytic rate / photocatalytic rate. Figure 9 This diagram illustrates the influence of the piezoelectric effect of the composite nanofiber materials provided in Examples 1 to 5 and Comparative Example 1 on the photocatalytic effect. Figure 9 It can be seen that the medium piezoelectricity of the BiOCl / CA composite nanofiber material obtained in Example 3 has a significant impact on photocatalysis.

[0109] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing BiOCl / CA composite nanofiber material, characterized in that, Includes the following steps: S10. Rice straw residue is treated with alkali to obtain rice straw cellulose; S20. After mixing and reacting the rice straw cellulose with glacial acetic acid, concentrated sulfuric acid and acetic anhydride, deionized water is added to precipitate the mixture. After washing with water, filtration, and freeze-drying, rice straw-derived cellulose acetate is obtained. S30. Mix BiOCl powder, polyvinylpyrrolidone powder, rice straw-derived cellulose acetate with an organic solvent to obtain a spinning solution; S40. Electrospin the spinning solution to obtain BiOCl / CA composite nanofiber material; In step S30, The organic solvent includes dichloromethane and glacial acetic acid, wherein the volume ratio of dichloromethane to glacial acetic acid is (2~2.5):1; The mass ratio of BiOCl powder, rice straw-derived cellulose acetate, and polyvinylpyrrolidone powder is (0.4~6):1:0.25; The mass concentration of rice straw-derived cellulose acetate in the spinning solution is 0.13~0.15 g / ml.

2. The preparation method of BiOCl / CA composite nanofiber material as described in claim 1, characterized in that, In step S40, The air humidity for electrospinning is 40-53%; and / or, The air temperature for electrospinning is 27~32℃.

3. The preparation method of the BiOCl / CA composite nanofiber material as described in claim 1, characterized in that, In step S20, The mass ratio of rice straw cellulose to glacial acetic acid, concentrated sulfuric acid, and acetic anhydride is 1:(8~19):(0.045~0.05):(4~5); and / or, The mixing temperature is 50~60℃; the mixing time is 1.5~2h.

4. The preparation method of the BiOCl / CA composite nanofiber material as described in claim 1, characterized in that, Step S10 includes: S101. Mix rice straw residue with potassium hydroxide solution, filter, and wash with deionized water until pH is neutral. S102. Mix the neutral solution with H2O2 solution, cool and filter, remove the filtrate, and obtain rice straw cellulose.

5. The preparation method of the BiOCl / CA composite nanofiber material as described in claim 4, characterized in that, In step S101, The potassium hydroxide solution has a mass concentration of 0.04~0.05 g / ml, and 4~5 g of rice straw residue is added to every 100 ml of potassium hydroxide solution; and / or, The mass concentration of the H2O2 solution is 0.02~0.03 g / ml; and / or, The volume ratio of the neutral solution to the H2O2 solution is 1:(2~2.5).

6. The method for preparing the BiOCl / CA composite nanofiber material as described in claim 1, characterized in that, Before step S10, the method further includes: S01. Rice straw is crushed to obtain rice straw powder. The rice straw powder is mixed with an ethanol aqueous solution in a reaction vessel to obtain a premixed solution. S02. Filter the premixed liquid, wash it, and take the filter residue to obtain rice straw residue.

7. The method for preparing the BiOCl / CA composite nanofiber material as described in claim 6, characterized in that, In step S01, the volume percentage of ethanol in the ethanol-water solution is 50%~95%; and / or, The rice straw powder has a mass concentration of 8-8.5 g / ml in the premixed solution; and / or, The mixing temperature is 180-200℃; and / or, The mixing time is 2-3 hours.

8. The method for preparing BiOCl / CA composite nanofiber material as described in claim 1, characterized in that, In step S30, the BiOCl powder is prepared by the following method: Bi(NO3)·5H2O, KCl, and deionized water were mixed, heated, cooled, washed, filtered, and dried to obtain flaky BiOCl powder.

9. The method for preparing the BiOCl / CA composite nanofiber material as described in claim 8, characterized in that, The molar ratio of Bi(NO3)·5H2O to KCl is 1:(1~1.1); and / or, The heating temperature is 150~200℃; and / or, The heating time is 18-24 hours; and / or, The drying temperature is 80~85℃; and / or, The drying time is 18-24 hours.

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