Preparation method and application of electrospinning-cured Cu-doped pyrite heterogeneous catalyst

Abstract

The application belongs to the technical field of composite materials, and relates to a preparation method of an electrospun solidified Cu-doped pyrite type heterogeneous catalyst, which comprises the following steps: dissolving iron salt and sulfur salt in deionized water, adding copper salt, stirring until the copper salt is completely dissolved, ultrasonic treatment for uniform dispersion, moving the solution to a hydrothermal reaction device for reaction, cooling to room temperature, filtering and recovering black precipitate, and preparing the heterogeneous catalyst; then, core-shell electrospinning is performed, and the hollow porous composite fiber is obtained after removing the solvent. The prepared electrospun solidified Cu-doped pyrite type heterogeneous catalyst is applied to a photo-Fenton composite system for photocatalytic removal of pollutants in wastewater. The preparation process of the required material is simple, easy to operate, and can be massively put into and produced in actual production. Through directional catalysis of the heterogeneous catalyst composite fiber catalyst, the specificity of the photocatalytic path of efficient and selective degradation of new micro-pollutants is regulated, and the activity and stability of the catalyst are improved.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and relates to photocatalysts, specifically to a method for preparing and applying a Cu-doped pyrite-type heterogeneous catalyst that is cured by electrospinning. Background Technology

[0002] The booming development of global industry has brought convenience to people's production and life, but it has also caused serious environmental pollution. Industries such as textile printing and dyeing, pharmaceuticals, and papermaking generate large amounts of wastewater, the organic pollutants of which are difficult to degrade and have high treatment costs. Photocatalysis technology has made wastewater treatment more effective, economical, and environmentally friendly to some extent. Nanoparticle photocatalysts are materials that can generate high-energy particles under specific wavelengths of light. They can react strongly with surrounding water and oxygen, producing superoxide ions, hydroxyl radicals, and other groups with extremely strong oxidation-reduction capabilities, thus purifying the air and treating wastewater. Photocatalysts are usually nanoscale semiconductor compounds. When used as photocatalysts, they simultaneously leverage their high surface area and photocatalytic properties, greatly improving photocatalytic efficiency and degrading pollutants in water into non-toxic and harmless small molecules, without causing secondary pollution, truly achieving green and pollution-free treatment. However, nanoparticle photocatalysts are generally in granular powder form, which has two fatal drawbacks when used as photocatalysts: they are prone to agglomeration, resulting in low reuse efficiency, and separation and recovery are difficult, easily leading to secondary pollution.

[0003] In recent years, non-metallic chalcogenides have been considered photocatalytic semiconductors due to their unique properties in degrading organic pollutants and splitting water. FeS2 holds a special place among these chalcogenide semiconductors due to its non-toxicity and high abundance on Earth. Among existing inorganic photovoltaic materials, FeS2 has the lowest extraction cost, and its excellent optical properties and suitable minority carrier diffusion length make it competitive in many optoelectronic devices. Doping transition metals into different semiconductors enhances photocatalytic activity due to increased light absorption, the creation of defects, or their role as trapping sites for electrons and holes.

[0004] Combining photocatalysis with electrospinning technology allows photocatalytic nanofiber membranes to be fabricated into two-dimensional or three-dimensional structures. Due to their small fiber diameter and large specific surface area, these membranes can increase contact with reactants, effectively compensating for the defects of catalyst particles. Furthermore, photocatalytic nanofiber membranes can be integrated with reaction devices to achieve large-scale wastewater treatment, which is of great significance for industrial wastewater treatment. Summary of the Invention

[0005] The purpose of this invention is to propose a method for preparing and applying a Cu-doped pyrite-type heterogeneous catalyst that is solidified by electrospinning. On the one hand, it solves the problems of catalyst source and engineering economy in photocatalytic wastewater treatment. On the other hand, it improves the specific surface area and structural characteristics of the catalyst, and to a certain extent compensates for the defects of catalyst particles, thus solving the problem of batch wastewater treatment.

[0006] Technical solution

[0007] Transition metal Cu was synthesized and doped into the semiconductor FeS2 structure via a hydrothermal method, thereby creating a wider light absorption range in the visible light range. The photocatalytic activity was improved due to the increased light absorption or the generation of defects or trapping sites for electrons and holes.

[0008] A method for preparing a Cu-doped pyrite-type heterogeneous catalyst by electrospinning and curing includes the following steps:

[0009] (1) Dissolve iron and sulfur salts in deionized water, then add copper salt. Stir until the copper salt is completely dissolved, then sonicate to disperse evenly. Transfer the solution to a hydrothermal reactor and react at 150–300°C for 6–40 minutes.

[0010] After 12 hours of natural cooling to room temperature, the black precipitate was recovered by filtration, washed several times with deionized water, and dried at 60°C for 4 hours. The resulting heterogeneous catalyst was named Pre-Cu@FeS2.

[0011] (2) Polyacrylonitrile (PAN) was added to dimethylformamide (DMF) and ultrasonically stirred for 2 hours. The prepared Pre-Cu@FeS2 and thermoplastic polyurethane (TPU) were added and mixed evenly at 98°C to obtain a shell polymer / solvent system. Propylene glycol polyether acetate (PMMA) dissolved in dimethylformamide (DMF) was used as the core liquid. Core-shell electrospinning was carried out. The hollow porous composite fiber obtained after removing the solvent is the electrospinned solidified Cu-doped pyrite heterogeneous catalyst.

[0012] In a preferred embodiment of the present invention, the iron salt in step (1) is one of ferrous sulfate, ferrous chloride, and ferric chloride, preferably ferrous sulfate (FeSO4·7H2O).

[0013] In a preferred embodiment of the present invention, the sulfate in step (1) is one of ammonium sulfate, ammonium thiosulfate, and sodium thiosulfate, preferably ammonium thiosulfate ((NH4)2S2O3).

[0014] In a preferred embodiment of the present invention, the copper salt in step (1) is one of copper chloride, copper nitrate, and copper sulfate, preferably copper nitrate.

[0015] In a preferred embodiment of the present invention, the material ratio of iron salt: copper salt: sulfur salt: water participating in the reaction in step (1) is 1-4 mmol: 1-4 mmol: 4-16 mmol: 50-100 mL, preferably 2 mmol: 2 mmol: 8 mmol: 50 mL.

[0016] In a preferred embodiment of the present invention, the hydrothermal reaction equipment in step (1) is an autoclave or a pressure vessel, preferably a hydrothermal autoclave, with the reaction time being 260°C for 9 hours.

[0017] In the preferred embodiment of the present invention, the core-shell electrospinning in step (2) uses the polymer / solvent system as the shell polymer and propylene glycol polyether acetate (PMMA) dissolved in dimethylformamide as the core liquid. The core liquid is sprayed by injection pumps, maintaining a potential difference of 10KV and a distance of 4.0cm between the needle and the collector. A grounded silicon wafer immersed in a non-solvent is used as the collector electrode. The collector is filled with a 1:1 (v / v) mixture of ethanol and acetone. The fiber is directly collected in the mixture, taken out, and air-dried at room temperature to remove the solvent. The resulting hollow porous composite fiber material is denoted as Cu@FeS2.

[0018] Furthermore, the polyacrylonitrile has a mass percentage of 9.5 wt%, with the remainder being dimethylformamide.

[0019] Furthermore, the mass percentage of PMMA solution in the dimethylformamide solution is 24 wt%.

[0020] Furthermore, the material ratio between Pre-Cu@FeS2 and TPU is 1-5 mmol:1-5 mmol, preferably 1 mmol:1 mmol.

[0021] Furthermore, during core-shell electrospinning, the inner diameter of the core fluid opening is 0.30 mm, and the inner diameter of the shell fluid opening is 0.80 mm.

[0022] Furthermore, the injection pump injects the shell polymer at a flow rate of 6.0 μL / min and the core fluid at a flow rate of 7.0 μL / min.

[0023] Another objective of this invention is to apply the electrospun solidified Cu-doped pyrite heterogeneous catalyst to a photocatalytic Fenton composite system for the photocatalytic removal of pollutants in wastewater, wherein the pollutant is tetracycline.

[0024] The successful doping of Cu in Pre-Cu@FeS2 was analyzed by SEM and the degradation effect of the prepared catalyst on tetracycline. Based on the above research, the catalytic performance of composite fiber materials prepared under different conditions was compared. It can be seen that Cu@FeS2 prepared by electrospinning technology has a degradation effect of about 90% on tetracycline under PMS.

[0025] Beneficial effects

[0026] The materials selected in this invention conform to the relevant concepts of green and environmental protection, and are significantly cheaper than traditional photocatalysis. In terms of preparation, the preparation process for the materials required by this invention is simple and easy to operate, thus enabling large-scale production in actual manufacturing. Regarding catalytic performance, the invention utilizes a heterogeneous catalyst composite fiber catalyst for directional catalysis, enabling the efficient and selective degradation of novel micropollutants through specific photocatalytic pathway regulation. This improves catalyst activity and stability, and has broad application prospects. Attached Figure Description

[0027] Figure 1 SEM-EDS of Cu@FeS2 prepared in Example 2;

[0028] Figure 2 The effect of Pre-7% Cu@FeS2, Cu@FeS2 and FeS2 on the photolysis of TC under PMS. Detailed Implementation

[0029] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] A method for preparing a Cu-doped pyrite-type heterogeneous catalyst includes the following steps: dissolving 2 mmol of a mixture of ferric chloride and copper chloride in a Fe:Cu (7 mol% Cu) ratio and 4 mmol of sodium thiosulfate in 40 mL of water and stirring for 10 min; then transferring the mixture to a 100 mL autoclave and sealing it, and steaming it at 150 °C for 12 h; after the reaction is complete, naturally cooling the container to room temperature, collecting the product, washing it several times with distilled water, and drying it at 60 °C for 4 h, the prepared FeS2 with a Cu content of 7 mol% is labeled as pre-7%-Cu@FeS2.

[0032] Weigh 10 mg of the prepared pre-7%-Cu@FeS2 and mix it with 100 μM PMS and TC under 500 W visible light. React for 120 min. Its degradation effect on various pollutants is 50-60%.

[0033] Example 2

[0034] A method for preparing a Cu-doped pyrite-type heterogeneous catalyst by electrospinning and curing includes the following steps:

[0035] (1) Dissolve 2 mmol of a mixture of ferric chloride and copper chloride in Fe:Cu (7 mol% Cu) ratio and 4 mmol of sodium thiosulfate in 40 mL of water and stir for 10 min; then transfer to a 100 mL autoclave and seal it, and steam at 150 °C for 12 h; after the reaction is complete, let the container cool naturally to room temperature, collect the product, wash it several times with distilled water, and dry it at 60 °C for 4 h. The structure of the prepared FeS2 with 7 mol% Cu content is labeled as pre-7%-Cu@FeS2.

[0036] (2) The obtained heterogeneous catalyst Pre-7%-Cu@FeS2 was fixed on a chemically stable thermoplastic polyurethane (TPU) matrix. 9.5 wt% polyacrylonitrile (PAN) was added to dimethylformamide (DMF) solution and ultrasonically stirred for 2 h. The prepared heterogeneous catalyst Pre-7%-Cu@FeS2 material and TPU were added to the above solution and mixed evenly at 98 °C. Then, core-shell electrospinning was performed through a customized nozzle. The inner diameter of the core fluid opening was 0.30 mm and the inner diameter of the shell fluid opening was 0.80 mm. 24 wt% PMMA solution in DMF was used as the core liquid and the above polymer / solvent system was used as the shell polymer. The electrospinning core and shell polymer were injected by an injection pump at flow rates of 6.0 and 7.0 μL / min, respectively. A potential difference of 10 kV and a distance of 4.0 cm were maintained between the needle (26 pressure gauge) and the collector. A grounded silicon wafer immersed in non-solvent was used as the collector.

[0037] (3) Fill the collector with a 1:1 (v / v) mixture of ethanol and acetone, collect the fiber directly in it, remove the collected material from the bath, air dry at room temperature to remove the solvent, and obtain hollow porous composite fiber material, labeled as 7%-Cu@FeS2.

[0038] Weigh 10 mg of 7%-Cu@FeS2 prepared in step (3), mix it with 100 μM PMS and TC under 500 W visible light, and react for 120 min. Its degradation effect on each pollutant is about 90%.

[0039] Figure 1 The results showed that the Fe / (Cu+S) ratio was close to 0.5, indicating that Cu was successfully doped at the S sites on the FeS2 surface.

[0040] Figure 2The antibacterial results showed that, compared with FeS2 and Pre-7%-Cu@FeS2, Cu@FeS2 achieved a photolysis efficiency of about 90% against tetracycline.

[0041] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. Use of an electrospun solidified Cu-doped pyrite-type heterogeneous catalyst, characterized in that, The application is applied to photocatalytic removal of tetracycline in wastewater in a photo-Fenton composite system, wherein the electrospun solidified Cu-doped pyrite type heterogeneous catalyst is prepared through the following steps: (1) Dissolve iron salt and sulfate in deionized water, then add copper salt, stir until the copper salt is completely dissolved, then ultrasonic treatment to disperse uniformly, move the solution to a hydrothermal reaction device to react at 150-300 DEG C for 6-12 h, naturally cool to room temperature, filter and recover black precipitate, wash with deionized water for several times, dry at 60 DEG C for 4 h, the prepared heterogeneous catalyst is recorded as Pre-Cu@FeS2, the material ratio of iron salt, copper salt, sulfate and water involved in the reaction is 1-4 mmol, 1-4 mmol, 4-16 mmol and 50-100 mL; (2) Add polyacrylonitrile PAN to dimethylformamide DMF, ultrasonic stirring and mixing for 2 h, add the prepared Pre-Cu@FeS2 and thermoplastic polyurethane TPU to mix uniformly at 98 DEG C to obtain a polymer / solvent system, use propylene glycol polyether acetate PMMA dissolved in dimethylformamide DMF as core liquid, carry out core-shell electrospinning, and the hollow porous composite fiber obtained after removing the solvent is the electrospun solidified Cu-doped pyrite type heterogeneous catalyst, wherein the core-shell electrospinning is that the polymer / solvent system is used as shell polymer, propylene glycol polyether acetate PMMA dissolved in dimethylformamide is used as core liquid, respectively injected through injection pumps, a potential difference of 10 KV and a distance of 4.0 cm are kept between the needle and the collector, a grounded silicon sheet immersed in a non-solvent is used as a current collector, a mixed liquid of ethanol and acetone with a volume ratio of 1:1 is filled in the collector, the fiber is directly collected in the mixed liquid, taken out, air-dried at room temperature, the solvent is removed, and the obtained hollow porous composite fiber material is recorded as Cu@FeS2.

2. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), the iron salt is one of ferrous sulfate, ferrous chloride and ferric chloride.

3. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 2, characterized in that: In step (1), the iron salt is ferrous sulfate.

4. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), the sulfate is one of ammonium sulfate, ammonium thiosulfate and sodium thiosulfate.

5. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 4, characterized in that: In step (1), the sulfate is ammonium thiosulfate.

6. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), the copper salt is one of copper chloride, copper nitrate and copper sulfate.

7. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 6, characterized in that: In step (1), the copper salt is copper nitrate.

8. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), the material ratio of iron salt, copper salt, sulfate and water is 2 mmol, 2 mmol, 8 mmol and 50 mL.

9. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), the hydrothermal reaction device is an autoclave or a high-pressure kettle.

10. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 9, characterized in that: In step (1), the hydrothermal reaction device is a high-pressure kettle.

11. Use of electrospun solidified Cu-doped pyrite-type heterogeneous catalyst according to claim 1, characterized in that: In step (1), hydrothermal reaction is carried out at 260 DEG C for 9 h.

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