A nickel-cobalt layered double hydroxide / bismuth tungstate heterojunction photocatalytic material and its preparation method and application

Abstract

This invention belongs to the field of advanced oxidation treatment of environmental pollutants, and provides a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material. The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material includes a support and a semiconductor composite therewith, wherein the support is nickel-cobalt layered bimetallic hydroxide, and the semiconductor is bismuth tungstate. This nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material is a semiconductor photocatalytic material with a wide visible light absorption range, good stability, excellent photocatalytic performance, and no secondary pollution. It can achieve efficient degradation of tetracycline under visible light and has good application prospects. The precursors used are widely available and inexpensive, making rational use of my country's existing resources to solve the pollution problems faced by my country.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation treatment of environmental pollutants, and relates to a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material, its preparation method and application. Background Technology

[0002] In recent years, environmental pollution has become increasingly serious, posing a major threat to human survival. Antibiotics are among the main environmental organic pollutants that interfere with the normal function of biological cells, making them extremely harmful to humans and the natural environment. Tetracycline is a representative broad-spectrum antibiotic that is difficult to degrade. Furthermore, large quantities of untreated antibiotics are discharged into natural water bodies, causing serious damage to the ecological environment. Therefore, the degradation of tetracycline antibiotics is crucial for environmental protection.

[0003] Currently, tetracycline wastewater treatment methods include biological treatment, ozone treatment, electrochemical treatment, and semiconductor photocatalysis. However, biological treatment methods have drawbacks such as high cost and difficulty in cultivating activated sludge; ozone treatment has drawbacks such as harsh operating environment and high cost; and electrochemical treatment has drawbacks such as high operating cost. These drawbacks prevent these methods from being widely used in wastewater treatment. Since its discovery in 1972, semiconductor photocatalysis technology has been widely used in pollutant degradation and photocatalytic hydrogen production due to its advantages of simple operation and low energy consumption. There has been much research on the application of semiconductor photocatalysis in the degradation of tetracycline, including TiO2 semiconductors and MOF semiconductors. Bi2WO6, as a novel semiconductor, is increasingly attracting researchers' attention.

[0004] Bi₂WO₆ is a simple and novel n-type narrow bandgap semiconductor photocatalyst material with a calcite-like layered structure. It possesses high visible light utilization efficiency, a stable crystal structure, and high quantum and electron transport efficiencies, making it a research hotspot in the field of semiconductor photocatalyst materials. Unfortunately, despite these inherent properties, it still suffers from drawbacks such as low photogenerated electron-hole pair separation efficiency and small specific surface area. Therefore, constructing heterojunctions of Bi₂WO₆ is proposed to further improve its photocatalytic performance. Summary of the Invention

[0005] To address the issues of low separation efficiency and small specific surface area of ​​photogenerated electron-hole pairs in Bi2WO6, this invention provides a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material.

[0006] The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material includes a support and a semiconductor composite therewith, wherein the support is a nickel-cobalt layered bimetallic hydroxide and the semiconductor is bismuth tungstate.

[0007] Furthermore, the mass ratio of the nickel-cobalt layered bimetallic hydroxide to the bismuth tungstate is 3-15:100.

[0008] This invention also provides the application of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material as described in any of the preceding claims in water treatment, wherein the water contains tetracycline, the photocatalytic reaction is carried out under visible light with a wavelength of 380 nm to 780 nm, and the photocatalytic reaction time is 0 to 100 min.

[0009] Furthermore, the amount of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalyst material added to the water body is 0.5 g / L, and the concentration of tetracycline in the water body is 20 mg / L.

[0010] Furthermore, the water body is ultrapure water, lake water, tap water, or rainwater.

[0011] The present invention also provides a method for preparing a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material.

[0012] The preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material includes the following steps:

[0013] Nickel-cobalt layered bimetallic hydroxide and bismuth tungstate monomer are added to a solvent to prepare a mixed suspension. The mixed suspension is subjected to a hydrothermal reaction under heating and pressure. The solid obtained after the reaction is completed is the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material.

[0014] Furthermore, the hydrothermal reaction temperature is 120℃~130℃, the hydrothermal reaction time is 16h~18h, and the stirring time is 2h~3h.

[0015] Furthermore, the mass ratio of the nickel-cobalt layered bimetallic hydroxide to the bismuth tungstate is 3-15:100.

[0016] Furthermore, the preparation method of the nickel-cobalt layered bimetallic hydroxide includes the following steps:

[0017] Ammonium chloride, sodium hydroxide, nickel chloride hexahydrate, and cobalt chloride hexahydrate are dissolved in deionized water to obtain a mixed solution. The mixed solution is reacted at 50℃~70℃ for 14h~16h. After the reaction is completed, the solid obtained is the nickel-cobalt layered bimetallic hydroxide.

[0018] The method for preparing the bismuth tungstate monomer includes the following steps:

[0019] Sodium tungstate dihydrate was dissolved in ethylene glycol and magnetically stirred for 30 min to obtain a sodium tungstate solution. Bismuth nitrate pentahydrate was dissolved in ethylene glycol and magnetically stirred for 30 min to obtain a bismuth nitrate solution. The bismuth nitrate solution was added dropwise to the sodium tungstate solution and stirred to mix. The mixed solution was then reacted at 170℃~190℃ for 24~26 h. The solid obtained after the reaction was the bismuth tungstate monomer.

[0020] The hydrothermal reaction also includes the following processing steps: washing and drying the product obtained after the hydrothermal reaction. The washing is performed by alternating washing with deionized water and anhydrous ethanol 3 to 4 times, and the drying temperature is 70℃ to 90℃ for 10 to 16 hours.

[0021] Furthermore, in the preparation method of the nickel-cobalt layered bimetallic hydroxide, the ratio of ammonium chloride, sodium hydroxide, nickel chloride hexahydrate, cobalt chloride hexahydrate, and deionized water in the mixed solution is 12 mmol: 5.5 mmol: 1.2 mmol: 1.2 mmol: 75 ml, and includes post-treatment of the nickel-cobalt layered bimetallic hydroxide: washing and drying the nickel-cobalt layered bimetallic hydroxide, wherein the washing process involves alternating washing with deionized water and anhydrous ethanol 3 to 4 times, and the drying is carried out in a forced-air oven at a temperature of 60℃ to 80℃ for 18h to 24h.

[0022] The method for preparing the bismuth tungstate monomer includes a method where the ratio of sodium tungstate dihydrate to ethylene glycol is 1 mmol: 30 ml, the ratio of bismuth nitrate pentahydrate to ethylene glycol in the bismuth nitrate solution is 0.2 mmol: 30 ml, the ratio of sodium tungstate dihydrate to bismuth nitrate pentahydrate is 5 mmol: 1 mmol, and the volume ratio of sodium tungstate solution to bismuth nitrate solution is 1:1. The method also includes post-treatment of the bismuth tungstate monomer: washing and drying the bismuth tungstate monomer. The washing process involves alternating between deionized water and anhydrous ethanol 3 to 4 times. The drying is carried out in a forced-air oven at a temperature of 60°C to 80°C for 10 to 16 hours.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] This invention provides a method for preparing a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material. The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material obtained by this method generates photogenerated holes and photogenerated electrons under visible light excitation. The oxidizing properties of the photogenerated holes and the reducing properties of the photogenerated electrons react with oxygen and water to generate superoxide radicals and hydroxyl radicals with stronger oxidizing and reducing properties. These active substances attack tetracycline in the water, promoting tetracycline mineralization and producing carbon dioxide and water, thereby achieving efficient removal of tetracycline from water using photocatalytic technology. This nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material is a semiconductor photocatalytic material with a wide visible light absorption range, good stability, excellent photocatalytic performance, and no secondary pollution. It can achieve efficient degradation of tetracycline under visible light and has good application prospects. The precursors used are widely available and inexpensive, making rational use of my country's existing resources to solve the pollution problems faced by my country. Attached Figure Description

[0025] Figure 1 A flowchart illustrating the preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material provided by this invention.

[0026] Figure 2 XRD patterns of A1, A2, A3, NiCo-LDH, and Bi2WO6.

[0027] Figure 3 Scanning electron microscope images of A2, NiCo-LDH, and Bi2WO6.

[0028] Figure 4 The graph shows the efficiency of tetracycline degradation in water using Examples 1-3 and Comparative Examples 1-2.

[0029] Figure 5 The graphs show the degradation effect of tetracycline on applications 2 and 4-7.

[0030] Figure 6 The graph shows the degradation effect of tetracycline in application example 8-11. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but this should not be construed as limiting the scope of the present invention.

[0032] This invention provides a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material. The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material comprises nickel-cobalt layered bimetallic hydroxide and bismuth tungstate, with bismuth tungstate attached to the nickel-cobalt layered bimetallic hydroxide, wherein the nickel-cobalt layered bimetallic hydroxide is NiCo-LDH. In this invention, bismuth tungstate is used as the host material because its valence band position is relatively positive, resulting in photogenerated holes with strong oxidation capabilities. NiCo-LDH is used as the modifying material because it has a narrow band gap, thus exhibiting a wide visible light absorption range; and due to its relatively negative conduction band position, the generated photogenerated electrons will have strong reduction capabilities. In the Z-type heterojunction photocatalysis process of this invention, under photoexcitation, electron-hole pairs at the valence band positions of NiCo-LDH and Bi2WO6 separate, and the generated photogenerated electrons are transferred to the conduction bands of NiCo-LDH and Bi2WO6, respectively. Under the action of potential, electrons on the conduction band of Bi2WO6 are transferred to the valence band of NiCo-LDH, at which point the photogenerated electrons recombine with the photogenerated holes on the valence band. Among the photogenerated electrons on the conduction band of NiCo-LDH, some participate in the degradation of tetracycline in water, and some react with oxygen in water to generate superoxide radicals. Among the photogenerated holes on the valence band of Bi2WO6, some participate in the degradation of tetracycline in water, and some react with water in water to generate hydroxyl radicals. The superoxide radicals generated on the conduction band and the hydroxyl radicals generated on the valence band react with pollutants in water, thereby achieving the purpose of degrading pollutants from water. On the one hand, the formation of the Z-shaped heterojunction allows electrons in the conduction band of Bi₂WO₆ to recombine with photogenerated holes in the valence band of NiCo-LDH, thereby reducing electron-hole pair recombination on both NiCo-LDH and Bi₂WO₆ and improving the photocatalytic performance of the composite material. On the other hand, compared to other semiconductors, the NiCo-LDH used in this invention has a narrower bandgap. When combined with bismuth tungstate, it forms a highly efficient Z-shaped heterojunction. Through the interaction between NiCo-LDH and Bi₂WO₆, the visible light absorption range of bismuth tungstate can be significantly improved, thus enhancing the utilization rate of sunlight by bismuth tungstate. Therefore, the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material of this invention is a semiconductor photocatalytic material with a wide visible light absorption range, excellent photocatalytic performance, and no secondary pollution. It can achieve efficient degradation of tetracycline under visible light and has good application prospects.

[0033] In the method of this invention, the bismuth tungstate in the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material is a bismuth-based semiconductor. Bismuth is known as a "green element," and my country has the world's largest reserves, accounting for 70% of the world's total reserves. Compared to traditional photocatalysts, the precursor used in this invention is widely available and inexpensive, making rational use of my country's existing resources to address the pollution problems my country faces. Therefore, the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material of this invention does not pollute the environment, and the raw materials are inexpensive and widely available, making it a green and environmentally friendly semiconductor photocatalytic material.

[0034] In this invention, bismuth tungstate is used as the main material and nickel-cobalt layered bimetallic hydroxide (NiCo-LDH) is used as the support material. A simple hydrothermal method can be used to prepare a NiCo-LDH / bismuth tungstate heterojunction photocatalytic material with high catalytic performance and high stability. Compared with other preparation methods, this invention's method is simple to operate, and the prepared material has high crystallinity and controllable morphology. This invention's preparation method has advantages such as controllable conditions, inexpensive raw materials, and simple operation, making it suitable for large-scale production and use, and possessing high application value.

[0035] By mixing a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material with water containing tetracycline and carrying out a photocatalytic reaction under visible light irradiation, the efficient degradation of tetracycline in water can be achieved. This invention's method for removing tetracycline from water is a novel advanced oxidation technology, the principle of which is shown in formulas (1) to (7). Compared with traditional technologies, the photocatalytic degradation technology used in this invention is a green and environmentally friendly technology. It utilizes solar energy as a reaction condition, is simple to operate, has a wide range of applications, the photocatalytic products do not cause secondary pollution to the environment, the catalytic process has low energy consumption, and the photocatalytic material is non-toxic and stable, allowing for repeated use and improving resource reuse efficiency. It has high application and commercial value.

[0036] (1) NiCo-LDH+hv→e - CB (NiCo-LDH)+h + VB (NiCo-LDH)

[0037] (2)Bi2WO6+hv→e - CB (Bi2WO6)+h + VB (Bi2WO6)

[0038] (3)e - CB (Bi2WO6)+h + VB(NiCo-LDH) → Composite

[0039] (4)e - CB (NiCo-LDH) + O2 → O2 - (NiCo-LDH)

[0040] (5)h + VB (Bi₂WO₆) + H₂O → ·OH(Bi₂WO₆) + H₂O +

[0041] (6)h + VB (Bi₂WO₆) + OH⁻ → ·OH(Bi₂WO₆)

[0042] (7)h + +·O2 - (NiCo-LDH) + ·OH(Bi2WO6) + TC → Degradation products

[0043] In this invention, the reusability of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material is used as an indicator of its practical application value. The heterojunction material composed of bismuth tungstate and nickel-cobalt layered bimetallic hydroxide exhibits excellent stability. After five consecutive treatments of tetracycline-containing water bodies under visible light irradiation, the catalytic ability of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material remains essentially unchanged and remains at a high level. Therefore, the heterojunction material composed of bismuth tungstate and nickel-cobalt layered bimetallic hydroxide possesses high stability, thereby improving the material's reusability. The material recovery method is also quite convenient; most of the material can be recovered simply by centrifugation, and the material loss is negligible. Thus, it can be seen that the heterojunction material composed of bismuth tungstate and nickel-cobalt layered bimetallic hydroxide of this invention has excellent stability, a simple recovery method, and a high reusability rate, making it a semiconductor photocatalytic material with high commercial value.

[0044] This invention provides a method for preparing a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material, comprising the following steps:

[0045] (1) Dissolve 12 mmol ammonium chloride, 5.5 mmol sodium hydroxide, 1.2 mmol nickel chloride hexahydrate and 1.2 mmol cobalt chloride hexahydrate in 75 ml deionized water to obtain a mixed solution. Then put the mixed solution into a high-pressure reactor and react at 55 °C for 15 h. After the reaction is completed, the stainless steel reactor is naturally cooled to room temperature. The reaction material inside the polytetrafluoroethylene liner is taken out and washed three times alternately with deionized water and anhydrous ethanol. The solid obtained after washing is placed in an oven and dried at 60 °C for 18 h to obtain nickel-cobalt layered bimetallic hydroxide (NiCo-LDH) material.

[0046] (2) Dissolve 1 mmol sodium tungstate dihydrate in 30 ml ethylene glycol and stir magnetically for 30 min to obtain sodium tungstate solution. Dissolve 0.2 mmol bismuth nitrate pentahydrate in 30 ml ethylene glycol and stir magnetically for 30 min to obtain bismuth nitrate solution. Add the bismuth nitrate solution dropwise to the sodium tungstate solution and stir to mix. Then put the mixed solution into a 100 ml reaction vessel and react at 180 °C for 24 h. After that, take out the reactants and wash them three times alternately with deionized water and anhydrous ethanol. Place the solid obtained after washing in an oven and dry it at 70 °C for 12 h. After washing and drying, bismuth tungstate (Bi2WO6) material is obtained.

[0047] (3) The nickel-cobalt layered bimetallic hydroxide (NiCo-LDH) material prepared in step (1) and the monomeric bismuth tungstate (Bi2WO6) material prepared in step (2) were added to 50 ml of ethanol solution in a certain proportion and stirred for 30 min. After stirring magnetically for 2 h, a mixed suspension of Bi2WO6 and NiCo-LDH was obtained. The mixed suspension was transferred to a 100 ml high-pressure reactor and reacted in an oven at 120 °C for 16 h. After the reaction was completed, the stainless steel reactor was naturally cooled to room temperature. The solid material inside the polytetrafluoroethylene liner was taken out and washed three times alternately with deionized water and anhydrous ethanol. The solid obtained after washing was placed in an oven and dried at 80 °C for 10 h to obtain the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material (NiCo-LDH / Bi2WO6).

[0048] In step (3), the volume of the mixed suspension is about half the volume of the 100ml high-pressure reactor.

[0049] Preparation Examples 1-3 were provided according to the above preparation method. The mass of the nickel-cobalt layered bimetallic hydroxide (NiCo-LDH) material added in step (3), the mass of the monomeric bismuth tungstate (Bi2WO6) material, and the product number are shown in the table below:

[0050] NiCo-LDH / g <![CDATA[Bi2WO6 / g]]> Product Number Preparation Example 1 0.003 0.1 A1 Preparation Example 2 0.009 0.1 A2 Preparation Example 3 0.015 0.1 A3

[0051] The XRD patterns of products A1, A2, A3, NiCo-LDH, and Bi2WO6 from Preparation Examples 1-3 are shown in... Figure 2 .

[0052] The scanning electron microscope (SEM) images of A2, NiCo-LDH, and Bi2WO6 in Preparation Example 2 are as follows: Figure 3 .

[0053] This invention also provides a method for removing tetracycline from water using photocatalytic materials, comprising the following steps:

[0054] 25 mg of photocatalyst was added to the solution to be treated and magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on the surface of the photocatalyst. Then, the photocatalytic reaction was carried out for 100 min under visible light with a wavelength of 380-780 nm. The photocatalytic reaction was carried out at a magnetic stirring speed of 880 r / min to complete the degradation treatment of tetracycline in the water.

[0055] Based on the above method for removing tetracycline from water using photocatalytic materials, application examples 1-11 and comparative examples 1-2 are provided. The differences between the application examples and the comparative examples lie in the type of photocatalyst, the solution to be treated, and the substances added to the solution to be treated, as detailed in the table below:

[0056]

[0057]

[0058] During the photocatalytic reaction, a sample was taken every 20 minutes. The sample was centrifuged to achieve solid-liquid separation, and the supernatant was collected. The concentration change was measured using a UV-Vis spectrophotometer to obtain the degradation efficiency of tetracycline by the photocatalyst.

[0059] Application Examples 1-8 and Comparative Examples 1-2 were all prepared with ultrapure water.

[0060] The efficiency of tetracycline degradation in water using Examples 1-3 and Comparative Examples 1-2 is shown in the figure. Figure 4 .

[0061] The degradation effects of tetracycline in Application Examples 2 and 4-7 are shown in [the original text]. Figure 5 .

[0062] The degradation effect of tetracycline in Application Examples 8-11 is shown in the figure. Figure 6 .

[0063] Results analysis:

[0064] Figure 2The presence of characteristic peaks for Bi₂WO₆ and NiCo-LDH in the XRD patterns of A1-A3 proves that the two substances have been successfully combined. Due to the small doping ratio of NiCo-LDH in NiCo-LDH / Bi₂WO₆, the characteristic peak of NiCo-LDH is not obvious in the XRD patterns of A1-A3, and only a very small characteristic peak appears in the XRD pattern of A3.

[0065] Figure 3 In the figure, (a), (b), and (c) represent Bi₂WO₆ nanospheres, NiCo-LDH nanosheets, and a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalyst (A2), respectively. Figure 3 As shown in (c), bismuth tungstate nanospheres are attached to NiCo-LDH nanosheets. This structure can provide more active sites and electron transfer channels for bismuth tungstate.

[0066] Figure 4 The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material of the present invention has a good degradation effect on tetracycline. When the mass ratio of nickel-cobalt layered bimetallic hydroxide to bismuth tungstate reaches 9:100, that is, the A2 degradation effect obtained in Preparation Example 2 is the best. If the content of nickel-cobalt layered bimetallic hydroxide is further increased, the photocatalytic degradation effect of the composite material will decrease.

[0067] Figure 5 As shown in the figure, NaCl and Na₂SO₄ have a strong inhibitory effect on the photocatalytic effect of nickel-cobalt layered bimetallic hydroxide / bismuth tungstate materials. This is because Cl... - and SO4 2- It participates in capturing free radicals and reacts with them, thereby reducing the level of free radicals and thus affecting the catalytic effect; CO3 2- The addition of CO3 reduces the adsorption capacity of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material surface, which may be due to CO3. 2- The adsorption of NO3 onto the catalyst surface, competing with tetracycline for active sites, ultimately leads to a slight decrease in photocatalytic treatment efficiency. - The addition of NO3 accelerated the entire catalytic process, but the final catalytic effect did not change significantly compared to the control group. This may be due to the fact that NO3... - The photolysis under light produced a small amount of ·OH, which is the cause; the results show that in Cl... - CO3 2- NO3 - and SO4 2- Even in the presence of coexisting ions, the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material still exhibits extremely high catalytic efficacy against tetracycline in water, demonstrating the wide applicability of this material.

[0068] Figure 6 In the figure, the vertical axis represents the ratio of the concentration of tetracycline after degradation to its initial concentration at a certain moment. As can be seen from the figure, the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material (A2) prepared in Example 1 of this invention achieved removal rates of 96.2%, 69.3%, 95.3%, and 84.3% for tetracycline in ultrapure water, lake water, tap water, and rainwater, respectively. The degradation rate of tetracycline in lake water was the lowest, which may be due to the excessive suspended matter in the lake water leading to uneven light exposure and thus affecting the photocatalytic effect; the decrease in the degradation rate of tetracycline in rainwater may be due to the presence of Cl in the rainwater. - This degradation is attributed to the capture of free radicals. The overall degradation level indicates that the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material of this invention exhibits highly efficient photocatalytic performance for tetracycline in different water source environments, achieving effective degradation of tetracycline in various water environments. This also demonstrates that the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalytic material of this invention can be widely used to treat tetracycline in different water source environments, showing good application prospects and practical applicability in the field of photocatalysis.

[0069] In the application example of this invention, the concentration of tetracycline in the water is 20 mg / L, and the amount of nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalyst added is 0.5 g / L. In other cases, although the concentration of tetracycline or the amount of nickel-cobalt layered bimetallic hydroxide / bismuth tungstate heterojunction photocatalyst added varies, a high tetracycline degradation rate can be obtained.

[0070] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material, characterized in that, It includes a carrier and a semiconductor composite therewith, wherein the carrier is a nickel-cobalt layered bimetallic hydroxide and the semiconductor is bismuth tungstate; The preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material includes the following steps: adding nickel-cobalt layered bimetallic hydroxide and bismuth tungstate monomer to a solvent to prepare a mixed suspension, and subjecting the mixed suspension to a hydrothermal reaction under heating and pressure. The solid obtained after the reaction is completed is the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material. The hydrothermal reaction temperature is 120℃~130℃, the hydrothermal reaction time is 16h~18h, and the stirring time is 2h~3h.

2. The nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 1, characterized in that, The mass ratio of the nickel-cobalt layered bimetallic hydroxide to the bismuth tungstate is 3-15:

100.

3. The application of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in any one of claims 1-2 in water treatment, characterized in that, The water contains tetracycline. The photocatalytic reaction is carried out under visible light with a wavelength of 380nm to 780nm. The photocatalytic reaction time is 0 to 100 minutes and is not 0 minutes.

4. The application of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 3 in water treatment, characterized in that... The amount of nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalyst added to the water body is 0.5 g / L, and the concentration of tetracycline in the water body is 20 mg / L.

5. The application of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 3 in water treatment, characterized in that, The water body is ultrapure water, lake water, tap water, or rainwater.

6. A method for preparing a nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in any one of claims 1-2, characterized in that, Includes the following steps: Nickel-cobalt layered bimetallic hydroxide and bismuth tungstate monomer are added to a solvent to prepare a mixed suspension. The mixed suspension is subjected to a hydrothermal reaction under heating and pressure. The solid obtained after the reaction is completed is the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material.

7. The preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 6, characterized in that, The hydrothermal reaction temperature is 120℃~130℃, the hydrothermal reaction time is 16h~18h, and the stirring time is 2h~3h.

8. The preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 6, characterized in that, The mass ratio of the nickel-cobalt layered bimetallic hydroxide to the bismuth tungstate is 3-15:

100.

9. The preparation method of the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 6, characterized in that, The method for preparing the nickel-cobalt layered bimetallic hydroxide includes the following steps: Ammonium chloride, sodium hydroxide, nickel chloride hexahydrate, and cobalt chloride hexahydrate are dissolved in deionized water to obtain a mixed solution. The mixed solution is reacted at 50℃~70℃ for 14h~16h. After the reaction is completed, the solid obtained is the nickel-cobalt layered bimetallic hydroxide. The method for preparing the bismuth tungstate monomer includes the following steps: Sodium tungstate dihydrate was dissolved in ethylene glycol and magnetically stirred for 30 min to obtain a sodium tungstate solution. Bismuth nitrate pentahydrate was dissolved in ethylene glycol and magnetically stirred for 30 min to obtain a bismuth nitrate solution. The bismuth nitrate solution was added dropwise to the sodium tungstate solution and stirred to mix. The mixed solution was then reacted at 170℃~190℃ for 24~26 h. The solid obtained after the reaction was the bismuth tungstate monomer. The hydrothermal reaction also includes the following processing steps: washing and drying the product obtained after the hydrothermal reaction, wherein the washing is performed by alternating washing with deionized water and anhydrous ethanol 3 to 4 times, the drying temperature is 70℃ to 90℃, and the drying time is 10h to 16h.

10. The method for preparing the nickel-cobalt layered bimetallic hydroxide / bismuth tungstate Z-type heterojunction photocatalytic material as described in claim 9, characterized in that, The preparation method of the nickel-cobalt layered bimetallic hydroxide includes a mixed solution in which the ratio of ammonium chloride, sodium hydroxide, nickel chloride hexahydrate, cobalt chloride hexahydrate, and deionized water is 12 mmol: 5.5 mmol: 1.2 mmol: 1.2 mmol: 75 ml, and includes post-treatment of the nickel-cobalt layered bimetallic hydroxide: washing and drying the nickel-cobalt layered bimetallic hydroxide, wherein the washing process involves alternating washing with deionized water and anhydrous ethanol 3 to 4 times, and the drying is carried out in a forced-air drying oven at a temperature of 60℃ to 80℃ for 18h to 24h. The method for preparing the bismuth tungstate monomer includes a method where the ratio of sodium tungstate dihydrate to ethylene glycol is 1 mmol: 30 ml, the ratio of bismuth nitrate pentahydrate to ethylene glycol in the bismuth nitrate solution is 0.2 mmol: 30 ml, the ratio of sodium tungstate dihydrate to bismuth nitrate pentahydrate is 5 mmol: 1 mmol, and the volume ratio of sodium tungstate solution to bismuth nitrate solution is 1:

1. The method also includes post-treatment of the bismuth tungstate monomer: washing and drying the bismuth tungstate monomer. The washing process involves alternating between deionized water and anhydrous ethanol 3 to 4 times. The drying is carried out in a forced-air oven at a temperature of 60°C to 80°C for 10 to 16 hours.

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