Bismuth-based photocatalytic heterojunction algicide as well as preparation method and application thereof

Abstract

The invention discloses a bismuth-based photocatalytic heterojunction algaecide and a preparation method and application thereof.The preparation method comprises the steps that bismuth salt and polyvinylpyrrolidone are mixed and then added into an alcohol compound to be mixed, and a mixed solution is obtained; adding a sodium halide solution into the mixed solution to obtain a suspension solution; adding molybdenum disulfide powder into the suspension solution, and stirring to obtain a uniform suspension solution; and carrying out high-temperature reaction on the suspension solution to obtain the bismuth-based photocatalytic heterojunction algaecide of a flaky composite material. According to the bismuth-based photocatalytic heterojunction algaecide prepared by the preparation method disclosed by the invention, after the bismuth-based photocatalytic heterojunction algaecide is added, sunlight is fully utilized for photocatalytic inactivation of algae cells, so that the light absorption range of a photocatalyst can be widened, secondary compounding of photo-induced electrons and holes is effectively solved, the photocatalytic efficiency of the catalyst is improved, and effective control of harmful algal blooms is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a preparation method of a bismuth-based photocatalytic heterojunction algae removal agent and application of the algae removal agent in treating water body algae. BACKGROUND

[0002] In recent years, due to excessive nitrogen and phosphorus in water, eutrophication of water bodies occurs, which threatens the health of aquatic ecological environment. The more prominent ecological hazards mainly come from the red tide and water bloom caused by the outbreak of algae, which brings challenges to human life and drinking water. Harmful algal blooms have the ability to release secondary metabolites such as biological toxins (e.g. algal toxins) and biologically active substances into natural water bodies, which can harm aquatic organisms such as fish, mammals and shellfish through the secretion of liver toxins and alkaloid neurotoxins. In addition, the outbreak of algae can also cause other adverse effects, for example, the metabolic products produced by algae emit a foul odor, reducing the drinkability of drinking water; the water body discoloration caused by the growth of algae on the surface of the water to a certain extent adversely affects the water quality; the algae growing near the water surface can reduce light penetration, potentially threatening the growth and reproduction of light-dependent aquatic organisms. Therefore, it is urgent to find an efficient algae control method to address the problem of algae outbreak.

[0003] At present, it has been found that photocatalytic technology is a promising method for removing algae. Compared with traditional treatment methods (chemical treatment, physical treatment and biological treatment), photocatalytic technology has many advantages such as high efficiency in removing algae, low treatment cost, simultaneous removal of algal toxins and other advantages, and is an environmentally friendly green treatment technology. Photocatalytic algae control technology mainly uses photocatalysts to be excited under light, and the valence band electrons jump to form photo-generated electrons and photo-generated holes, and free radicals are generated on the surface of the catalyst by reaction, which uses the strong oxidizing property of the generated free radicals to inactivate algal cells. Due to its unique electronic structure, good visible light response and relatively stable chemical properties, bismuth-based photocatalysts have great application potential in the field of photocatalysis. Bismuth-based catalysts are a class of semiconductor materials with bismuth as the core element, which have been widely studied in recent years in the fields of pollutant degradation, environmental remediation and energy conversion. Common bismuth-based catalysts include bismuth molybdate (Bi2MoO6), bismuth tungstate (Bi2WO6), bismuth sulfide (Bi2S3), bismuth titanate (Bi2Ti2O7), bismuth vanadate (BiVO4) and bismuth oxyhalide (BiOX), etc. These bismuth-based photocatalysts have the advantages of narrow band gap, strong visible light response and high photo-generated charge separation efficiency, but also have the problems of high photo-generated carrier recombination rate and insufficient stability, resulting in low photocatalytic efficiency.

[0004] The single bismuth-based photocatalytic material has a narrow light absorption range, a high electron-hole recombination rate and a limited oxidation capacity, so it is of great significance to develop a bismuth-based photocatalyst with simple preparation process, high catalytic efficiency and green environmental protection for removing harmful algae in water.

[0005] Therefore, there is an urgent need to provide an algae removal agent with a wide light absorption range, a small electron-hole recombination rate and a strong oxidation capacity. SUMMARY

[0006] The purpose of the present application is to provide a bismuth-based photocatalytic heterojunction algae removal agent and a preparation method. The precursor solution of bismuth oxyhalide nanomaterial is obtained at room temperature by liquid phase precipitation method, and the successful construction of heterojunction between bismuth oxyhalide and molybdenum disulfide makes the prepared photocatalyst have a wider light absorption range and inhibit the secondary combination of photo-generated electrons and holes, so as to effectively improve the catalytic efficiency of the synthesized photocatalyst and realize effective control of harmful algae blooms.

[0007] The present application is realized by the following technical solutions.

[0008] In one aspect of the present application, a preparation method of a bismuth-based photocatalytic heterojunction algae removal agent is provided, comprising the following steps:

[0009] a. A bismuth salt is mixed with polyvinylpyrrolidone according to a mass ratio of (1-2) : 1 : (70-80), and then added into an alcohol compound to obtain a mixed solution;

[0010] b. A sodium halide solution is added into the mixed solution according to a mass ratio of (4-6) : (20-25) of sodium halide to bismuth salt to obtain a suspension solution;

[0011] c. Molybdenum disulfide powder is added into the turbid solution according to a molar concentration ratio of (0.1-2) : 1 of molybdenum disulfide to bismuth salt, and a uniform suspension solution is obtained after stirring;

[0012] d. The suspension solution is subjected to high-temperature reaction, and the precipitate is centrifuged, washed, dried, ground and sieved to obtain a bismuth-based photocatalytic heterojunction algae removal agent.

[0013] Preferably, the bismuth salt comprises one of bismuth nitrate or bismuth chloride.

[0014] Preferably, the alcohol compound is glycerol or ethylene glycol.

[0015] Preferably, the sodium halide is a mixture of sodium bromide and sodium iodide according to a molar ratio of 1:1, and the volume ratio of sodium bromide solution to sodium iodide solution is (5-6) : 1.

[0016] Preferably, the high-temperature reaction temperature is 160-180 DEG C, and the reaction time is 10-12 hours.

[0017] Preferably, the centrifugal speed is 4000-6000 r / min, and the centrifugal time is 10-15 minutes; the precipitate is washed with water for 3-4 times.

[0018] Preferably, the drying temperature is 60-80 DEG C, and the drying time is 10-12 hours.

[0019] Preferably, the grinding is performed through a 100-mesh screen.

[0020] In another aspect of the present application, a bismuth-based photocatalytic heterojunction algae-removal agent prepared by the method is provided, wherein the bismuth-based photocatalytic heterojunction algae-removal agent is a sheet-shaped heterojunction photocatalytic nanomaterial formed by compounding bismuth oxyhalide and molybdenum disulfide.

[0021] In still another aspect of the present application, a spraying device for the bismuth-based photocatalytic heterojunction algae-removal agent is provided, which comprises a medicament stirring tank, an algae-removal agent feeding port arranged at the top of the medicament stirring tank, a connecting pipe arranged at the bottom of the medicament stirring tank, a stirring paddle arranged in the medicament stirring tank, a rotatable spray head connected to the end of the connecting pipe, and a water pump connected to the connecting pipe to spray the prepared algae-removal agent into algae liquid.

[0022] The present application has the following beneficial effects due to the above technical solutions:

[0023] 1. The preparation method of the bismuth-based photocatalytic heterojunction algae-removal agent first prepares a precursor solution of bismuth oxyhalide nanomaterial at room temperature by a liquid-phase precipitation method, then adds molybdenum disulfide powder to obtain a suspension solution after stirring, and finally synthesizes sheet-shaped composite nanomaterial through high-temperature hydrothermal reaction. The successful construction of the heterojunction between the two semiconductor materials of bismuth oxyhalide and molybdenum disulfide can widen the light absorption range of the photocatalyst, effectively solve the problem of the secondary combination of photo-generated electrons and holes, and improve the photocatalytic efficiency of the catalyst.

[0024] 2. The bismuth-based photocatalytic heterojunction algae-removal agent obtained by the method is prepared by a liquid-phase precipitation method and a hydrothermal method, and the preparation method is simple and avoids complicated operations.

[0025] 3. The bismuth-based photocatalytic heterojunction algae-removal agent obtained by the method is a sheet-shaped bismuth oxyhalide-molybdenum disulfide composite nanomaterial, and after visible light irradiation for 6 hours, the oxidation capacity is greatly improved compared with the bismuth oxyhalide and molybdenum disulfide catalysts alone. Under light irradiation, the photo-generated electron-hole pairs of the bismuth-based photocatalytic heterojunction algae-removal agent generate strong oxidizing substances on the surface of the composite material to oxidize the algal cells, destroy the metabolic activity and antioxidant activity of the algal cells, and ultimately lead to the loss of activity of the algal cells, so that the algal cells cannot continue to reproduce, and the removal rate of the algal cells is more than 90%. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0027] Figure 1 X-ray photoelectron spectroscopy full spectrum of the bismuth-based photocatalytic heterojunction algae removal agent;

[0028] Figure 2 Scanning electron microscope image of the bismuth-based photocatalytic heterojunction algae removal agent;

[0029] Figure 3 Comparison chart of algae control effect of the bismuth-based photocatalytic heterojunction algae removal agent prepared in Examples 1-5;

[0030] Figure 4 Structure schematic diagram of the spraying device of the bismuth-based photocatalytic heterojunction algae removal agent. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail with reference to the drawings and specific examples, and the schematic examples and descriptions of the present application are used to explain the present application, but are not as a limitation of the present application. The reagents used in the examples are all conventional products that can be obtained by marketing.

[0032] According to one aspect of the present application, a preparation method of a bismuth-based photocatalytic heterojunction algae removal agent is proposed, which specifically comprises the following steps:

[0033] Step a, according to the mass ratio of (1-2) : 1 : (70-80), the bismuth salt and polyvinylpyrrolidone are mixed and then added into an alcohol compound to obtain a mixed solution.

[0034] Among them, the bismuth salt is one of bismuth nitrate or bismuth chloride. The alcohol compound is glycerol or ethylene glycol.

[0035] In a preferred embodiment, the volume ratio of the alcohol compound to water in the alcohol compound solution in step a is 1:1.

[0036] Polyvinylpyrrolidone is used as a surfactant, which aims to regulate the morphology, dispersibility and stability of the material, inhibit the agglomeration of the material, selectively adsorb on a specific crystal face during the synthesis of the material, regulate the growth direction of the crystal, and form a high-activity crystal face.

[0037] The alcohol compound can limit the migration of particles, reduce the agglomeration of nanoparticles to obtain a more uniform dispersion system, and the participation of the alcohol compound can enhance the morphology regulation effect of polyvinylpyrrolidone on the synthesized material.

[0038] Step b, according to the mass ratio of sodium halide and bismuth salt is (4-6):(20-25), sodium halide solution is added to the mixed solution to obtain a suspension solution.

[0039] In a preferred embodiment, the sodium halide in step b is a mixture of sodium bromide and sodium iodide in a molar ratio of 1:1, and the volume ratio of sodium bromide solution to sodium iodide solution is (5-6):1.

[0040] The sodium bromide solution and the sodium iodide solution are added at the same time to ensure that bromine ions and iodine ions are effectively doped in the material to form bismuth oxyhalide.

[0041] Step c, according to the molar concentration ratio of molybdenum disulfide to bismuth salt is (0.1-2):1, molybdenum disulfide powder is added to the turbid solution, and after stirring, a uniform suspension solution is obtained.

[0042] Excessive molybdenum disulfide can cover the surface of bismuth oxyhalide, shielding the active sites on the surface of the material, reducing the light absorption of bismuth oxyhalide, and reducing the photocatalytic activity of the material. At the same time, the introduction of excessive molybdenum disulfide will cause the agglomeration of molybdenum disulfide, which cannot form an effective heterojunction structure, resulting in the recombination of photo-generated electron-hole pairs inside molybdenum disulfide or at the bismuth oxyhalide-molybdenum disulfide heterojunction interface.

[0043] Step d, after the suspension solution is hydrothermally treated at 160-180℃ for 10-12h, the precipitate is centrifuged at 4000-6000r / min for 10-15min, washed with water 3-4 times, dried at 60-80℃ for 10-12h, and ground through a 100 mesh sieve to obtain a sheet-shaped bismuth-based photocatalytic heterojunction nanomaterial algal removal agent.

[0044] The bismuth-based photocatalytic heterojunction algal removal agent obtained by the method of the present application is a sheet-shaped bismuth oxyhalide-molybdenum disulfide composite nanomaterial. The addition of molybdenum disulfide can form a heterojunction with bismuth oxyhalide to inhibit the secondary recombination of photo-generated electron-hole pairs, prolong the lifetime of photo-generated carriers, and effectively enhance the photocatalytic efficiency of the composite material to achieve efficient removal of algal cells.

[0045] The following is a further description of the preparation of the bismuth-based photocatalytic heterojunction algal removal agent of the present application through a variety of specific examples and comparative examples. It should be noted that these examples are only for a more detailed description and should not be understood as limiting the present application in any form.

[0046] Example 1

[0047] A method for preparing a bismuth-based photocatalytic heterojunction algal removal agent, comprising the following steps:

[0048] 1) Mix 25mL of glycerol and 25mL of ultrapure water to prepare a 50% glycerol solution.

[0049] 2) According to the mass ratio of 1:1:75, bismuth nitrate pentahydrate powder and polyvinylpyrrolidone powder are added to 50% glycerol solution, and the powder is dissolved at a speed of 600 rpm to obtain a colorless transparent solution.

[0050] 3) According to the mass ratio of sodium halide to bismuth nitrate of 5:22, sodium bromide solution and sodium iodide solution are added to the colorless transparent solution, and after magnetic stirring, an orange yellow suspension solution is formed. The volume ratio of sodium bromide solution to sodium iodide solution is 5:1.

[0051] 4) According to the molar concentration ratio of 0.1:1 of molybdenum disulfide to bismuth nitrate, molybdenum disulfide powder is added to the turbid solution, and stirred uniformly at a speed of 400 rpm.

[0052] 5) Pour the prepared solution into a polytetrafluoroethylene lined reaction kettle, and calcine at a high temperature of 180℃ for 10h, then centrifuge the precipitate at a speed of 5000r / min for 12 minutes, wash with water for 3 times, dry at 70℃ for 10h, take out and grind to powder with a mortar, pass through a 100 mesh sieve, and prepare a sheet-shaped bismuth-based photocatalytic heterojunction nanomaterial algaecide.

[0053] Example 2

[0054] A preparation method of a bismuth-based photocatalytic heterojunction algaecide, comprising the following steps:

[0055] 1) Mix 25mL of glycerol and 25mL of ultrapure water to prepare a 50% glycerol solution.

[0056] 2) According to the mass ratio of 1.5:1:70, bismuth nitrate pentahydrate powder and polyvinylpyrrolidone powder are added to 50% glycol solution, and the powder is dissolved at a speed of 600 rpm to obtain a colorless transparent solution.

[0057] 3) According to the mass ratio of sodium halide to bismuth nitrate of 4:23, sodium bromide solution and sodium iodide solution are added to the colorless transparent solution at the same time, and after magnetic stirring, an orange yellow solution is formed. The volume ratio of sodium bromide solution to sodium iodide solution is 5.5:1.

[0058] 4) According to the molar concentration ratio of 0.5:1 of molybdenum disulfide to bismuth nitrate, molybdenum disulfide powder is added to the turbid solution, and stirred uniformly at a speed of 400 rpm.

[0059] 5) Pour the prepared solution into a polytetrafluoroethylene lined reaction kettle, and calcine at a high temperature of 165℃ for 11h, then centrifuge the precipitate at a speed of 4000r / min for 15 minutes, wash with water for 3 times, dry at 60℃ for 12h, grind and pass through a 100 mesh sieve, and prepare a sheet-shaped bismuth-based photocatalytic heterojunction nanomaterial algaecide.

[0060] Example 3

[0061] A preparation method of a bismuth-based photocatalytic heterojunction algae removal agent, comprising the following steps:

[0062] 1) Mix 25 mL of glycerol and 25 mL of ultrapure water to prepare a 50% glycerol solution.

[0063] 2) Add bismuth chloride powder and 0.4 g of polyvinylpyrrolidone powder to the 50% glycerol solution according to a mass ratio of 2:1:76, and dissolve the powders at a speed of 600 rpm to obtain a colorless transparent solution.

[0064] 3) According to the mass ratio of sodium halide to bismuth chloride of 5.5:25, add sodium bromide solution and sodium iodide solution to the colorless transparent solution at the same time, and form an orange yellow solution after magnetic stirring. The volume ratio of sodium bromide solution to sodium iodide solution is 5.8:1.

[0065] 4) Add molybdenum disulfide powder to the turbid solution according to a molar concentration ratio of 1:1 of molybdenum disulfide to bismuth chloride, and stir uniformly at a speed of 400 rpm.

[0066] 5) Pour the prepared solution into a reaction kettle with a polytetrafluoroethylene liner, calcine at a high temperature of 170℃ for 12h, centrifuge the precipitate at a speed of 4500r / min for 11 minutes, wash with water for 3 times, dry at 75℃ for 10h, and grind through a 100 mesh sieve to obtain a flaky bismuth-based photocatalytic heterojunction nanomaterial algae removal agent.

[0067] Example 4

[0068] A preparation method of a bismuth-based photocatalytic heterojunction algae removal agent, comprising the following steps:

[0069] 1) Mix 25 mL of glycerol and 25 mL of ultrapure water to prepare a 50% glycerol solution.

[0070] 2) Add bismuth chloride powder and 0.4 g of polyvinylpyrrolidone powder to the 50% glycerol solution according to a mass ratio of 2:1:76, and dissolve the powders at a speed of 600 rpm to obtain a colorless transparent solution.

[0071] 3) According to the mass ratio of sodium halide to bismuth chloride of 5.5:25, add sodium bromide solution and sodium iodide solution to the colorless transparent solution at the same time, and form an orange yellow solution after magnetic stirring. The volume ratio of sodium bromide solution to sodium iodide solution is 5.8:1.

[0072] 4) Add molybdenum disulfide powder to the turbid solution according to a molar concentration ratio of 1:1 of molybdenum disulfide to bismuth chloride, and stir uniformly at a speed of 400 rpm.

[0073] 5) Pour the prepared solution into a reaction kettle with a polytetrafluoroethylene liner, and calcine at a high temperature of 175°C for 11 h. Centrifuge the precipitate at a speed of 5500 r / min for 12 min, wash with water for 3 times, dry at 65°C for 11 h, and grind through a 100 mesh sieve to obtain a flaky bismuth-based photocatalytic heterojunction nanomaterial algal removal agent.

[0074] Example 5

[0075] A preparation method of a bismuth-based photocatalytic heterojunction algal removal agent, comprising the following steps:

[0076] 1) Mix 25 mL of glycerol and 25 mL of ultrapure water to prepare a 50% glycerol solution.

[0077] 2) Add 0.4 g of polyvinylpyrrolidone powder and 50% glycerol solution to the bismuth nitrate pentahydrate powder in a mass ratio of 1.8:1:72, and dissolve the powder at a speed of 600 rpm to obtain a colorless transparent solution.

[0078] 3) Add sodium bromide solution and sodium iodide solution to the colorless transparent solution in a mass ratio of 6:24, and stir magnetically to form an orange yellow solution. The volume ratio of sodium bromide solution to sodium iodide solution is 6:1.

[0079] 4) Add molybdenum disulfide powder to the turbid solution in a molar concentration ratio of 2:1, and stir uniformly at a speed of 400 rpm.

[0080] 5) Pour the prepared solution into a reaction kettle with a polytetrafluoroethylene liner, and calcine at a high temperature of 160°C for 12 h. Centrifuge the precipitate at a speed of 5000 r / min for 12 min, wash with water for 3 times, dry at 70°C for 10 h, and grind through a 100 mesh sieve to obtain a flaky bismuth-based photocatalytic heterojunction nanomaterial algal removal agent.

[0081] Comparative Example

[0082] A preparation method of a bismuth oxyhalide photocatalyst, comprising the following steps:

[0083] 1) Mix 25 mL of glycerol and 25 mL of ultrapure water to prepare a 50% glycerol solution.

[0084] 2) Add 0.48 g of bismuth nitrate pentahydrate powder and 0.4 g of polyvinylpyrrolidone powder to the 50% glycerol solution, and dissolve the powder at a speed of 600 rpm to obtain a colorless transparent solution.

[0085] 3) Add 4.25 mL of sodium bromide solution and 0.75 mL of sodium iodide solution to the colorless transparent solution, and stir magnetically to form an orange yellow solution.

[0086] 4) Pour the prepared solution into a 100 mL polytetrafluoroethylene-lined reaction kettle, calcine at 180°C for 10 h, and then cool to room temperature. Centrifugally wash the reaction product with water for multiple times, and place in a drying oven at 60°C for 12 h. Take out and grind into powder with a mortar, and pass through a 100-mesh sieve.

[0087] 5) Obtain the bismuth oxyhalide photocatalyst.

[0088] Figure 1 X-ray photoelectron spectroscopy full spectrum of the bismuth-based photocatalytic heterojunction algae-removal agent obtained in Example 4; Figure 2 Scanning electron microscope image of the bismuth-based photocatalytic heterojunction algae-removal agent obtained in Example 4.

[0089] As shown in Figure 1 , six elements of Bi, Mo, O, Br, I and S are detected in the composite material obtained by the method of the application, indicating the successful synthesis of the bismuth oxyhalide and the molybdenum disulfide. It can be seen from the scanning electron microscope image that the bismuth-based photocatalytic heterojunction algae-removal agent prepared has a sheet structure.

[0090] The bismuth-based photocatalytic heterojunction algae-removal agent obtained in Examples 1-5 and the bismuth oxyhalide photocatalyst obtained in the comparative example are subjected to algae-removal effect test, and the specific test method is as follows:

[0091] The prepared composite material is added to 80 mL of algae liquid (Microcystis aeruginosa, initial algae density is 2 x 10 6 cells / mL, which is equivalent to the algae density at the time of algal bloom), and placed in a light reaction device with a xenon lamp. The ultraviolet light below 420 nm is filtered out with a filter, and the light is continuously reacted for 6 h. The chlorophyll a is taken out every 1 h as an algae cell removal index to evaluate the algae-removal effect.

[0092] The test results are shown in Table 1.

[0093] Table 1

[0094]

[0095] As can be seen from the results in Table 1, the removal rate of chlorophyll a of the bismuth-based photocatalytic heterojunction algae-removal agent obtained by the method of the application is more than 90% after 6 h of light reaction, which has excellent algae-removal effect. According to the test, it is found that the algae-removal agent prepared in Example 4 exhibits the best algae-removal performance. Under the same reaction conditions, the removal efficiency of chlorophyll a of the bismuth oxyhalide photocatalyst obtained in the comparative example is only 32.7%, which is much lower than the algae-removal efficiency of the heterojunction composite material prepared in the examples. In summary, the bismuth-based photocatalytic heterojunction composite material prepared in the application has high-efficiency algae-removal performance.

[0096] Figure 3 The removal efficiency of algal chlorophyll a of the bismuth-based photocatalytic heterojunction algae-removal agent obtained in Examples 1-5 and the bismuth oxyhalide photocatalyst obtained in the comparative example was tested under light irradiation for 6 hours. Figure 3 As can be seen from Table 1, the algae-removal efficiency of the bismuth-based photocatalytic heterojunction algae-removal agent of the present application increased with the increase of the reaction time, and the algae-removal efficiency was significantly improved after 2 hours of reaction. However, the algae-removal efficiency of the bismuth oxyhalide photocatalyst was slow in removing chlorophyll a within 6 hours of light reaction.

[0097] Further analysis showed that, compared with Example 4, the content of molybdenum disulfide in Example 5 was too high in step 4). It was found that the algae-removal efficiency of the bismuth-based photocatalytic heterojunction algae-removal agent obtained in Example 4 was higher than that of the bismuth-based photocatalytic heterojunction algae-removal agent obtained in Example 5. This is because too much molybdenum disulfide covers the surface of bismuth oxyhalide, shielding the active sites on the surface of the material, reducing the light absorption of bismuth oxyhalide, and reducing the photocatalytic activity of the material. At the same time, the introduction of excessive molybdenum disulfide causes the agglomeration of molybdenum disulfide, which cannot form an effective heterojunction structure, resulting in the recombination of photo-generated electron-hole pairs inside the molybdenum disulfide or at the interface of the bismuth oxyhalide-molybdenum disulfide heterojunction.

[0098] Further, as shown in Figure 4 the present application also provides a device for spraying the bismuth-based photocatalytic heterojunction algae-removal agent, which comprises a medicament stirring tank 2, an algae-removal agent feeding port 3 is arranged at the top of the medicament stirring tank 2, a connecting pipe 7 is arranged at the bottom of the medicament stirring tank 2, a stirring paddle 4 is arranged in the medicament stirring tank 2, the stirring paddle 4 is driven to stir by a motor 1, the medicament stirring tank 2 is supported by a base 5, a rotatable spray head 10 is connected to the end of the connecting pipe 7, and the connecting pipe 7 is connected to a water pump 8 to spray the prepared algae-removal agent solution into the algae liquid.

[0099] In operation, the algae-removal agent and water are added into the medicament stirring tank 2 through the feeding port 3, the algae-removal agent and water are fully mixed by the stirring paddle 4 driven by the motor 1, then the valve 6 is opened, the water enters the connecting pipe 7, and the medicament solution fills the water outlet pipe 9 under the suction of the water pump 8, finally the solution is sprayed into the algae-removal area through the spray head 10, the algae-removal agent is put into the water, and the harmful algae is controlled.

[0100] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for preparing a bismuth-based photocatalytic heterojunction algaecide, characterized in that, Includes the following steps: a. Mix bismuth salt and polyvinylpyrrolidone in a mass ratio of (1-2):1:(70-80), then add the mixture to an alcohol compound to obtain a mixed solution; b. Add sodium halide solution to the mixed solution according to the mass ratio of sodium halide to bismuth salt of (4-6):(20-25) to obtain a suspension solution; c. Add molybdenum disulfide powder to the turbid solution at a molar ratio of molybdenum disulfide to bismuth salt of (0.1-2):1, and stir to obtain a uniform suspension. d. After the suspension solution is reacted at high temperature, the precipitate is centrifuged, washed, dried, ground and sieved to obtain a bismuth-based photocatalytic heterojunction algaecide of sheet-like composite material.

2. The preparation method of a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, The bismuth salt includes either bismuth nitrate or bismuth chloride.

3. The preparation method of a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, The alcohol compound is glycerol or ethylene glycol.

4. The preparation method of a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, The sodium halide is a mixture of sodium bromide and sodium iodide in a molar ratio of 1:1, and the volume ratio of sodium bromide solution to sodium iodide solution is (5-6):

1.

5. The preparation method of a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, The high-temperature reaction temperature is 160–180℃, and the reaction time is 10–12 hours.

6. The method for preparing a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, Centrifuge at 4000-6000 r / min for 10-15 minutes; wash the precipitate with water 3-4 times.

7. The preparation method of a bismuth-based photocatalytic heterojunction algaecide according to claim 1, characterized in that, The drying temperature is 60-80℃, and the drying time is 10-12 hours.

8. A bismuth-based photocatalytic heterojunction algaecide prepared by the method according to any one of claims 1-8.

9. The application of a bismuth-based photocatalytic heterojunction algaecide as described in claim 8 in the treatment of aquaculture water bodies.

10. A spraying device for the bismuth-based photocatalytic heterojunction algaecide according to claim 8, characterized in that, It includes a chemical mixing tank, with an algaecide dosing port at the top and a connecting pipe at the bottom. The mixing tank contains a stirring paddle, and the end of the connecting pipe is connected to a rotatable nozzle. The connecting pipe is connected to a water pump to spray the algaecide solution into the algae solution.

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