A wO3 / g-c3n4 / nickel-foam photocatalytic film and a preparation method and application thereof

Abstract

The application provides a WO3 / g-C3N4 / Ni-foam photocatalytic film and a preparation method and application thereof. The application mainly loads a WO3 / g-C3N4 photocatalyst on the surface of a nickel foam film according to a gel method and a hydrothermal method, and makes the photocatalyst form a composite photocatalytic material on the surface of the nickel foam film, so that effective degradation of dodecylmorpholine in water is realized, no extra energy consumption is caused by using sunlight as an energy source, and secondary pollution of water is avoided, the method is suitable for treating dodecylmorpholine in water, and the method is simple, remarkable in effect, safe and environment-friendly, and easy to recycle. The application has important significance for low-energy-consumption and pollution-free treatment of the floatation agent dodecylmorpholine in salt lake brine.

Description

Technical Field

[0001] This invention belongs to the field of salt lake brine treatment and environmental protection, specifically relating to a WO3 / g-C3N4 / Ni-foam photocatalytic thin film, its preparation method, and its application. Background Technology

[0002] The main method for preparing potassium salts is to enrich potassium elements in salt lake brine. This requires adding flotation agents to the salt lake brine to float the potassium salts. Dodecylmorpholine (DMP) is one of the most commonly used flotation agents today. However, adding large amounts of flotation agents to salt lakes can damage the ecological environment of the salt lakes. Therefore, it is necessary to treat the residual flotation agents in the salt lake water in a timely manner.

[0003] Currently, factories mostly use electrocatalysis to treat industrial wastewater containing DMP, i.e., dielectric barrier discharge plasma. However, this method has the following drawbacks: First, the electrocatalytic method is more expensive, as the electrocatalytic process continuously applies a strong current to the wastewater, consuming a large amount of energy; second, a large amount of Cr-containing substances must be added during the reaction. 3+ Fe 3+ The solution caused secondary pollution.

[0004] Addressing the shortcomings of electrocatalysis, photocatalysis, utilizing solar energy for semiconductor photodegradation, is widely considered a promising technology for eliminating organic pollutants in water due to its advantages such as non-toxicity, recyclability, and being a green and renewable energy source. The mechanism of photocatalytic oxidation-reduction mainly involves the catalyst absorbing light energy upon exposure to light, undergoing electron transitions to generate electron-hole pairs. These pairs directly oxidize or reduce pollutants adsorbed on the surface, or oxidize OH- ions on the surface to generate highly oxidizing hydroxyl radicals (·OH) or superoxide radicals (·O2). - ), which oxidizes pollutants.

[0005] Currently, most photocatalysts are prepared as powder materials, which are difficult to recover after being placed in water to degrade pollutants, resulting in a high recovery loss rate. Therefore, preparing photocatalyst materials as membrane materials facilitates recovery and reuse after catalytic reactions, with a simple recovery method and low loss rate. Although photocatalytic degradation of pollutants in water has been applied in many fields, methods for using photocatalysis to treat the flotation agent dodecylmorpholine in salt lake brine are very rare. Therefore, if photocatalysis is used to degrade dodecylmorpholine, the key technology lies in synthesizing a highly efficient photocatalyst for degrading dodecylmorpholine. Summary of the Invention

[0006] In the course of implementing this invention, the inventors discovered that g-C3N4 possesses unique properties such as high stability (even in strong acid and strong alkali solutions), low cost, and a band gap of 2.7 eV, making it a promising candidate material for photocatalytic processes using solar energy as a light source. However, pure g-C3N4 exhibits rapid photogenerated carrier recombination and poor absorption in the visible light region, resulting in low photocatalytic activity under visible light irradiation. Therefore, exploring g-C3N4-based photocatalysts with enhanced photocatalytic activity has become increasingly important. In recent years, strategies such as doping with metal or non-metal elements, increasing surface area, and coupling with other semiconductors have been employed to improve the photocatalytic activity of g-C3N4.

[0007] Tungsten trioxide (WO3) exhibits excellent visible light absorption due to its suitable band gap, high chemical stability, and favorable electron transport behavior. WO3 is a non-toxic, photostable semiconductor with a band gap of 2.6-2.8 eV, capable of absorbing visible light. However, due to its insufficient conduction band potential, WO3 cannot generate superoxide radicals in photocatalytic reactions. Constructing a Z-type heterojunction between g-C3N4 and WO3 can effectively improve electron separation and migration efficiency, thereby enhancing photocatalytic activity.

[0008] Nickel foam is a typical three-dimensional porous material due to its low density, high mechanical strength, and good thermal and chemical stability. Furthermore, its large specific surface area provides numerous active catalytic sites, which is beneficial for improving photocatalytic activity. Therefore, nickel foam is an ideal support material for photocatalysts.

[0009] Taking all these considerations into account, this invention loads powdered / g-C3N4 onto a thin-film nickel foam material using a gelation method, and then grows modified WO3 on the film surface using a hydrothermal method to form a composite WO3 / g-C3N4 / Ni-foam photocatalytic film.

[0010] Specifically, the preparation method includes the following steps:

[0011] (1) Weigh rosin resin, morpholine, ammonia and deionized water and put them into a beaker;

[0012] (2) Place the material obtained in step (1) in an oil bath and stir to react, to obtain rosin gel;

[0013] (3) g-C3N4 was prepared by calcining dicyandiamide;

[0014] (4) Grind the g-C3N4 until there are no obvious particles, then add it to the rosin gel and mix evenly to obtain a hydrogel;

[0015] (5) Apply the hydrogel obtained in step (4) to the surface of the nickel foam film;

[0016] (6) The hydrogel-coated nickel foam film obtained in step (5) is placed in a tube furnace and calcined to obtain a nickel foam film loaded with g-C3N4.

[0017] (7) Dissolve Na2WO4•H2O in water, add HCl solution to adjust the pH to 1.9-2.1, and then add water to obtain solution A;

[0018] (8) Add glacial acetic acid to solution A to adjust the pH to 2.2-2.4, then stir well to obtain solution B;

[0019] (9) The nickel foam film obtained in step (6) is placed vertically in solution B and hydrothermally reacted at 155-165℃ for 14-18 h. After cooling to room temperature, it is taken out, washed and vacuum dried to obtain WO3 / g-C3N4 / Ni-foam photocatalytic film.

[0020] Preferably, in step (2), the oil bath temperature is 50-60℃ and the stirring rate is 150-250 r / min.

[0021] Preferably, in step (3), the heating rate of calcination is 4-6℃ / min, and the temperature is maintained for 3-5 h after reaching 545-555℃.

[0022] Preferably, the concentration of the HCl solution in step (7) is 1-2 mol / L.

[0023] Preferably, the stirring rate in step (8) is 150-250 r / min and the stirring time is 20-40 min.

[0024] Preferably, in step (9), the washing method is alternating washing with water and alcohol; in step (9), the vacuum drying temperature is 45-55℃, and the vacuum drying time is 22-26 h.

[0025] A WO3 / g-C3N4 / Ni-foam photocatalytic thin film prepared according to the above preparation method.

[0026] An application of a WO3 / g-C3N4 / Ni-foam photocatalytic thin film as described above in the degradation of dodecylmorpholine in water.

[0027] Preferably, it includes:

[0028] The WO3 / g-C3N4 / Ni-foam photocatalytic film was added to water containing dodecylmorpholine and stirred in the dark for 25-35 min, and then reacted under light for 50-70 min.

[0029] One method is to use a 300W xenon lamp with a filter to simulate sunlight and provide a light source.

[0030] Preferably, the ratio of the WO3 / g-C3N4 / Ni-foam photocatalytic film to water containing dodecylmorpholine is 0.08-0.12 g: 90-110 mL, the concentration of dodecylmorpholine in the water is 7-9 mmol / L, and the pH of the water is 3.0-3.2.

[0031] Unless otherwise specified, the equipment, reagents, processes, parameters, etc. involved in this invention are all conventional equipment, reagents, processes, parameters, etc., and no further examples will be provided.

[0032] All ranges listed in this invention include all point values ​​within that range.

[0033] In this invention, "room temperature" refers to the normal ambient temperature, which can be 10 to 30°C.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] This invention targets dodecylmorpholine in water bodies. It utilizes a photocatalyst formed by a composite of modified WO3 and graphite-type g-C3N4 to construct a Z-type heterojunction, thereby enhancing the catalytic performance of the material and improving the degradation efficiency of dodecylmorpholine. Furthermore, it avoids the accumulation of excess pollutants that contaminate the water body, effectively degrading small amounts of dodecylmorpholine in the water and preventing dodecylmorpholine from damaging and polluting mineral deposits in the water, thus achieving the goal of environmental protection.

[0036] Furthermore, the preparation method of the present invention is simple to operate, has high quality and good repeatability. Compared with the existing DMP degradation technology, it has higher efficiency, no secondary pollution, and the catalyst is easy to recover and reuse. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 The X-ray diffraction pattern of the WO3 / g-C3N4 / Ni-foam photocatalytic thin film in Example 1 of this invention is shown.

[0039] Figure 2 a)- Figure 2f) is a scanning electron microscope image of the WO3 / g-C3N4 / Ni-foam photocatalytic thin film in Example 1 of the present invention.

[0040] Figure 3 The graph shows the photocatalytic degradation performance of dodecylmorpholine solution by the WO3 / g-C3N4 / Ni-foam photocatalytic film in Example 1 of this invention.

[0041] Figures 4(a)-4(c) show the cyclic degradation patterns of dodecyl morpholine solution by the WO3 / g-C3N4 / Ni-foam photocatalytic thin film in Example 1 of the present invention.

[0042] Figure 5 The graph shows the photocatalytic degradation performance of dodecylmorpholine solution by the WO3 / g-C3N4 / Ni-foam photocatalytic film in Example 2 of this invention. Detailed Implementation

[0043] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0044] Example 1

[0045] A method for preparing a WO3 / g-C3N4 / Ni-foam photocatalytic thin film is as follows:

[0046] (1) Weigh 12 g of rosin resin, 1 g of morpholine, 3.5 g of ammonia and 83.5 g of deionized water and put them into a beaker;

[0047] (2) The material obtained in step (1) is placed in an oil bath and stirred at 60°C to obtain rosin gel;

[0048] (3) Dicyandiamide was placed in a muffle furnace and calcined at 550°C for 4 hours to prepare g-C3N4;

[0049] (4) Grind the g-C3N4 obtained in step (3) until there are no obvious particles, weigh 0.9 g and add it to 15 g of rosin gel and mix evenly;

[0050] (5) Apply the hydrogel obtained in step (4) to the surface of the nickel foam film;

[0051] (6) The hydrogel-coated nickel foam film obtained in step (5) is placed in a tube furnace and heated to 320°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 2 h to obtain a nickel foam film loaded with g-C3N4.

[0052] (7) Dissolve 1.65 g Na2WO4•H2O in water, add 1 mol / L HCl solution to adjust the pH to 1.9-2.1, and then add water to obtain solution A;

[0053] (8) Add glacial acetic acid to solution A to adjust the pH to 2.2-2.4, then stir well to obtain solution B;

[0054] (9) The nickel foam film obtained in step (6) was placed vertically in solution B and hydrothermally reacted at 160°C for 16 h. After cooling to room temperature, it was taken out, washed and vacuum dried at 50°C to obtain WO3 / C3N4 / Ni-foam photocatalytic film.

[0055] The X-ray diffraction pattern of the prepared WO3 / C3N4 / Ni-foam photocatalytic film is shown in Figure 1. Three distinct characteristic peaks can be observed in the XRD pattern of the nickel foam film, located at 44.94°, 52.32°, and 76.76°. After loading g-C3N4 onto the surface of the nickel foam film using hydrogel, XRD testing revealed a broad peak at 28.18°, a characteristic peak of g-C3N4, indicating successful loading of g-C3N4 onto the film surface after the reaction. Furthermore, the characteristic peak of nickel foam shifts to the right after calcination, suggesting a decrease in the interplanar spacing of nickel foam after calcination. XRD testing of the WO3 / C3N4 / Ni-foam sample after hydrothermal reaction showed a significant decrease in the intensity of the characteristic peaks of nickel foam after the hydrothermal reaction. This is attributed to the weakening of the characteristic peaks of the nickel foam film due to the growth of WO3 on the film surface. Furthermore, peaks were observed at 28.65°, 37.62°, and 49.95° for all samples. By comparing with the WO3 standard card (PDF#75-2187), these peaks correspond to the (1 0 1), (2 1 0), and (2 2 0) crystal planes of WO3, indicating that WO3 was successfully grown on the surface of the g- / C3N4 / Ni-foam film after the hydrothermal reaction.

[0056] The surface morphology of the WO3 / C3N4 / Ni-foam photocatalytic film was observed using scanning electron microscopy. Figure 2 a)- Figure 2 b) is nickel foam, which exhibits a sponge-like porous structure with pore sizes ranging from 100 μm to 400 μm. The width of the nickel foam morphology on the film is approximately 60 μm. The morphology of g-C3N4 / Ni-foam obtained after hydrogel loading of g-C3N4 powder is as follows: Figure 2 c) Figure 2d) Scanning electron microscopy revealed a large number of bulk g-C3N4 particles loaded on the film surface. The size of these bulk g-C3N4 negative powder particles ranged from 20 μm to 100 μm. The voids in the nickel foam on the film surface were filled by the bulk g-C3N4 negative powder, indicating that the g-C3N4 negative was successfully loaded onto the film surface after calcination. WO3 grew on the film surface, exhibiting a flower-like structure. Figure 2 e) Figure 2 f), the WO3 sheets were tightly bonded to the film surface, and their lengths were between 20 μm and 30 μm, indicating that the WO3 successfully grew on the film surface after the hydrothermal reaction. The degradation of dodecylmorpholine on the WO3 / g-C3N4 / Ni-foam photocatalytic film was tested, and the degradation effect was measured by ultraviolet spectrophotometry. The results are as follows: Figure 3 As shown, under simulated sunlight, the degradation efficiency of nickel foam film for DMP was 21.03% after 60 min. Considering the natural degradation effect, this indicates that the degradation effect of nickel foam film on DMP is poor.

[0057] After loading g-C3N4 onto the surface of a nickel foam film via hydrogel, the degradation efficiency of DMP reached 33.37% after 60 min, showing a certain improvement compared to the monomeric substance. This indicates that loading C3N4 onto the film surface enhances the catalytic activity, suggesting an interaction between the two rather than simply loading it onto the film surface. Under the same test conditions, the WO3 / g-C3N4 / Ni-foam photocatalytic film significantly improved the degradation efficiency of DMP, achieving a degradation efficiency of 49.3% for DMP after 60 min. This demonstrates that the WO3 / g-C3N4 / Ni-foam photocatalytic film significantly degrades dodecylmorpholine, effectively removing dodecylmorpholine from water.

[0058] As shown in Figures 4(a)-4(c), this embodiment also conducted a stability experiment on the WO3 / g-C3N4 / Ni-foam photocatalytic film to test its degradation ability after multiple degradation cycles. After 5 cycles, the catalytic performance of the photocatalytic film did not decrease significantly, indicating that the photocatalytic film has good stability at a low number of cycles. After completing 6-15 cycles, the overall catalytic performance of the photocatalytic film decreased by 12%, indicating that the photocatalytic film can still maintain about 80% of its catalytic performance in high cycles, has good stability, and is easy to recover.

[0059] Example 2

[0060] The difference from Example 1 is that the amount of g-C3N4 added was changed to 1.0 g when preparing the WO3 / g-C3N4 / Ni-foam photocatalytic film.

[0061] After the catalyst synthesis was completed, the synthesized WO3 / g-C3N4 / Ni-foam photocatalytic film was added to 100 ml of an 8 mmol / L dodecylmorpholine solution. The mixture was stirred in a dark reactor for 30 min to allow the catalyst and solution to reach adsorption equilibrium. Then, the solution was placed under a light source, and the reaction was carried out under illumination with stirring for 60 min. Samples were taken every 10 min to test the concentration of dodecylmorpholine in the solution, and the degradation rate was calculated. The results are as follows: Figure 5 As shown, the composite WO3 / g-C3N4 / Ni-foam photocatalytic film achieved a degradation efficiency of 45% for dodecylmorpholine in solution, which is a significant improvement compared to the monomer, and has a significant effect on the degradation of dodecylmorpholine in a short time.

[0062] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a WO3 / g-C3N4 / Ni-foam photocatalytic film, characterized in that, The preparation method comprises the following steps: (1) weighing rosin resin, morpholine, ammonia water and deionized water into a beaker; (2) placing the material obtained in step (1) into an oil bath pot for stirring reaction to obtain a rosin hydrogel; (3) preparing g-C3N4 by calcining dicyandiamide; (4) grinding the g-C3N4 to be free of obvious particles, then adding the rosin hydrogel to mix uniformly to obtain a hydrogel; (5) scraping the hydrogel obtained in step (4) on the surface of a nickel foam film; (6) placing the nickel foam film coated with the hydrogel obtained in step (5) into a tube furnace for calcination to obtain a nickel foam film loaded with g-C3N4; (7) dissolving Na2WO4•H2O in water, adding an HCl solution to adjust the pH value to 1.9-2.1, and then adding water to obtain an A solution; (8) adding glacial acetic acid to the A solution to adjust the pH value to 2.2-2.4, and then stirring uniformly to obtain a B solution; (9) vertically placing the nickel foam film obtained in step (6) in the B solution for hydrothermal reaction at 155-165 DEG C for 14-18 h, taking out after cooling to room temperature, washing and vacuum drying to obtain a WO3 / g-C3N4 / Ni-foam photocatalytic film.

2. The method of claim 1, wherein: In step (2), the temperature of the oil bath pot is 50-60 DEG C, and the stirring rate is 150-250 r / min.

3. The production method according to claim 1, wherein: In step (3), the heating rate of calcination is 4-6 DEG C / min, and the temperature is kept at 545-555 DEG C for 3-5 h; in step (6), the heating rate of calcination in the tube furnace under a nitrogen atmosphere is 4-6 DEG C / min, and the temperature is kept at 305-330 DEG C for 2-3 h.

4. The production method according to claim 1, wherein: In step (7), the concentration of the HCl solution is 1-2 mol / L, and the amount of water added is 4-6 times the amount of water used for dissolving Na2WO4•H2O.

5. The production method according to claim 1, wherein: In step (8), the stirring rate is 150-250 r / min, and the stirring time is 20-40 min.

6. The production method according to claim 1, wherein: In step (9), the washing mode is alternating washing with water and alcohol; in step (9), the temperature of vacuum drying is 45-55 DEG C, and the time of vacuum drying is 22-26 h.

7. A WO3 / g-C3N4 / Ni-foam photocatalytic film prepared by the preparation method according to any one of claims 1 to 6.

8. Application of the WO3 / g-C3N4 / Ni-foam photocatalytic film prepared in claim 7 to degradation of dodecylmorpholine in water.

9. Use according to claim 8, characterized in that: The WO3 / g-C3N4 / Ni-foam photocatalytic film is added into water containing dodecylmorpholine, and is placed in the dark for stirring for 25-35 min, and then is reacted under light for 50-70 min.

10. Use according to claim 8, characterized in that: The ratio of the WO3 / g-C3N4 / Ni-foam photocatalytic film to the water containing dodecylmorpholine is 0.08-0.12 g:90-110 mL, the concentration of the dodecylmorpholine in the water is 7-9 mmol / L, and the pH value of the water is 3.0-3.2.

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