Zncofe-lDH / mns2 photocatalyst, preparation method and application thereof

Abstract

The application provides a ZnCoFe-LDH / MnS2 photocatalyst, a preparation method and application thereof, the ZnCoFe-LDH / MnS2 photocatalyst is successfully compounded by in-situ hydrothermal synthesis method, and a new ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is formed. The addition of MnS2 makes the UV-vis of ZnCoFe-LDH red shift, and the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial has a wider visible light absorption range than ZnCoFe-LDH. Moreover, the introduction of MnS2 successfully realizes the separation of the photo-generated electron-hole pairs of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial at the heterojunction (ZnCoFe-LDH and MnS2), thereby avoiding the rapid in-situ recombination of the electron-hole pairs in the band gap of the single ZnCoFe-LDH catalytic nanomaterial, and being helpful to the separation of the photo-generated carriers and the reduction of the band gap. In addition, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided by the embodiment of the application has a degradation efficiency of phenol of up to 100% within 60 min; compared with the single ZnCoFe-LDH photocatalytic nanomaterial, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial has a wider range of visible light absorption and a higher ability to activate PMS to degrade phenol.

Description

Technical Field

[0001] This invention relates to the fields of chemical manufacturing equipment and carbon materials technology, and in particular to a ZnCoFe-LDH / MnS2 photocatalyst, its preparation method, and its application. Background Technology

[0002] Among various phenol-containing wastewater treatment technologies, advanced oxidation processes (AOPs) have attracted widespread attention due to their strong oxidation capacity and fast reaction rate. In particular, persulfate (PMS)-based AOPs have significant advantages in pollutant removal: 1) PMS is inexpensive, easy to store, and has low transportation costs; 2) PMS can be effectively activated within a wide pH range (3.0-10.0); 3) PMS has an asymmetric structure, readily dissociating into sulfate radicals (SO42-). ·- It can degrade organic pollutants over a long period of time.

[0003] However, PMS requires external force (energy or chemicals) to be activated and generate reactive oxygen species that can degrade pollutants. Photocatalytic oxidation technology is a novel environmental pollution control technology with advantages such as low cost, no secondary pollution, and the ability to degrade almost all organic pollutants. It has been proven to have practical and potential application value in many areas such as wastewater treatment and air purification, and has received widespread attention both domestically and internationally.

[0004] However, existing photocatalysis technologies still have some drawbacks, such as high catalyst preparation costs, low solar energy utilization, fast photogenerated electron-hole recombination rates, and difficulties in separating and recovering powdered photocatalysts. These directly restrict the further application of photocatalytic activation of PMS for phenol degradation.

[0005] Therefore, developing new photocatalytic nanomaterials with high catalytic activation efficiency, good stability, and reusability is a key research focus in this field. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides a ZnCoFe-LDH / MnS2 photocatalytic nanomaterial, its preparation method, and its application. By combining ZnCoFe-LDH with MnS2, a heterojunction composite photocatalytic nanomaterial with a simple preparation method, better stability, and reusability is developed. This addresses the problem of low efficiency in the catalytic activation of PMS for phenol degradation by existing visible light catalysts, thereby realizing the construction of a highly efficient and environmentally friendly photocatalytic purification system for phenol-containing wastewater.

[0007] The specific details of the invention are as follows:

[0008] In a first aspect, a method for preparing ZnCoFe-LDH / MnS2 photocatalytic nanomaterials, the method comprising:

[0009] Step 1: Disperse ZnCoFe-LDH powder in a certain amount of deionized water to form a suspension with a ZnCoFe-LDH concentration of 2-3 g / L;

[0010] Step 2: Add a first mixed solution containing thiourea and MnCl2·4H2O in a molar ratio of 2:1 to the suspension, and mix well to form a first solid-liquid blend;

[0011] Step 3: Transfer the solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out the first hydrothermal reaction at 180-200℃. Collect the solid product after the reaction by centrifugation, and then wash and vacuum dry it to obtain the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial.

[0012] Optionally, in step 1, the dispersion is performed using ultrasound, and the ultrasonic dispersion time is 30-60 minutes.

[0013] Optionally, in step 3, the first hydrothermal reaction is carried out for 20-24 hours.

[0014] Optionally, in step 3, the washing process includes: washing with deionized water and ethanol alternately 6-10 times;

[0015] The vacuum drying process is carried out at a temperature of 60-80℃ and for a duration of 12-24 hours.

[0016] Optionally, the ZnCoFe-LDH is prepared by the following steps:

[0017] Step 11: Dissolve Zn(NO3)2·6H2O, Co(NO3)2·6H2O and Fe(NO3)3·9H2O in deionized water to form Zn 2+ Co 2+ with Fe 3+ The molar ratio is [M] 2+ ] / [M 3+ A precursor solution with a ratio of 2:1;

[0018] Step 12: Add the precursor solution dropwise to a second mixed solution containing NaOH and Na2CO3 in a molar ratio of (2-3):1, and stir vigorously at 60-90℃ for 2-3 hours to form the second solid-liquid blend.

[0019] Step 13: Transfer the second solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out a second hydrothermal reaction at 110-120°C. Collect the solid precipitate after the reaction is completed by centrifugation, and then wash and vacuum dry it to obtain the ZnCoFe-LDH powder.

[0020] Optionally, in step 13, the second hydrothermal reaction is carried out for 20-24 hours.

[0021] Optionally, in step 13, the washing process includes washing with deionized water and ethanol alternately 6-10 times.

[0022] Optionally, in step 13, the temperature of the vacuum drying process is 60-80℃; and the time of the vacuum drying process is 12-24h.

[0023] In a second aspect, the present invention provides a ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by the preparation method described in the first aspect above.

[0024] Thirdly, the present invention provides an application of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by the preparation method described in the first aspect above, wherein the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is used for visible light catalytic activation of persulfate to degrade phenol in wastewater to be treated;

[0025] In the wastewater to be treated, the initial concentration of ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is 100 mg / L, the initial concentration of phenol is 10 mg / L, and the concentration of persulfate is 0.1 mM. Under visible light irradiation, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial photocatalytically activates the persulfate, and the degradation efficiency of phenol can reach 100% within 60 min.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention provides a method for preparing ZnCoFe-LDH / MnS2 photocatalytic nanomaterials. Through in-situ hydrothermal synthesis, ZnCoFe-LDH and MnS2 are successfully combined to form a new ZnCoFe-LDH / MnS2 photocatalytic nanomaterial. The addition of MnS2 causes a redshift in the UV-vis of ZnCoFe-LDH, resulting in a wider visible light absorption range for the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial compared to ZnCoFe-LDH alone. Furthermore, the introduction of MnS2 successfully enables the separation of photogenerated electron-hole pairs at the heterojunction (ZnCoFe-LDH and MnS2), thus avoiding the rapid in-situ recombination of electrons and holes in the band gap of a single ZnCoFe-LDH catalytic nanomaterial, which facilitates the separation of photogenerated carriers and the narrowing of the band gap.

[0028] Furthermore, experiments demonstrated that when the dosages of ZnCoFe-LDH / MnS2, ZnCoFe-LDH alone, and MnS2 alone were all the same (initial concentration of 100 mg / L), the phenol content in the wastewater to be treated was the same (initial concentration of 30 ppm), the initial concentration of PMS was the same (0.1 mM), the initial temperature was room temperature, and the conditions were met under two standard solar intensities (2000 mW / cm²). 2 Under visible light (λ>400nm) irradiation, ZnCoFe-LDH / MnS2 photocatalytic nanomaterials, single ZnCoFe-LDH, and single MnS2 were used to catalyze the degradation of phenol in wastewater by PMS. Due to the limited absorbance of single ZnCoFe-LDH, the degradation efficiency of phenol by PMS was only 16% within 30 minutes. Although single MnS2 has good absorbance, its high photogenerated electron-hole recombination rate resulted in a degradation efficiency of 55% for phenol by PMS within 60 minutes. In contrast, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided in this embodiment achieved a degradation efficiency of 100% for phenol within 60 minutes. Compared to single ZnCoFe-LDH photocatalytic nanomaterials, ZnCoFe-LDH / MnS2 photocatalytic nanomaterials have a wider visible light absorption range and a more efficient ability to activate PMS for phenol degradation.

[0029] Furthermore, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided by this invention maintained a 100% efficiency in catalytically activating PMS to degrade phenol in three consecutive degradation experiments, with no significant loss in degradation rate. This demonstrates that the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials have good stability, can be recycled, and have potential application value in the field of air purification. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating the preparation method of ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided in this embodiment of the invention is shown.

[0032] Figure 2 A flowchart illustrating the preparation method of ZnCoFe-LDH material provided in an embodiment of the present invention is shown.

[0033] Figure 3The SEM image of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided in the embodiments of the present invention is shown.

[0034] Figure 4 The ultraviolet diffuse reflectance spectra of the photocatalytic nanomaterials provided in the embodiments and comparative examples of the present invention are shown.

[0035] Figure 5 The N2 adsorption-desorption isotherm of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided in the embodiments of the present invention is shown.

[0036] Figure 6 The Fourier diffuse reflectance infrared spectra of the photocatalytic nanomaterials provided in the embodiments and comparative examples of the present invention are shown.

[0037] Figure 7 The following diagram shows a comparison of the photocatalytic degradation performance of phenol by the photocatalytic nanomaterials provided in the embodiments and comparative examples of the present invention;

[0038] Figure 8 The experiment illustrates the reusability of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided in this embodiment of the invention for degrading phenol. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0040] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0041] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0042] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0043] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Layered bimetallic hydroxides (LDHs, [M] 1-x 2+ M x 3+ [(OH)2](A n- ) x / n LDH (mH2O), also known as hydrotalcite-like clay, is a quasi-two-dimensional sandwich structure. The two-dimensional layers are formed by stacking MO6 octahedra (with M at the center and six oxygen anions at the corners) along one direction, with anions connecting the layers. It has advantages such as low cost, simple preparation, large surface area, flexible interlayer structure for electron transfer, and abundant active sites. LDH layers are connected by anions, and this intercalation method increases the interlayer spacing, making the entire framework more conducive to charge carrier transfer between layers. This not only provides more adsorption and active sites for photocatalytic reactions but also helps improve the separation efficiency of electron-hole pairs. In recent years, LDH has attracted much attention due to its ability to enhance catalytic activity through coupling with other materials. However, LDH also suffers from drawbacks such as a wide band gap, low visible light utilization, and easy recombination of photogenerated electron-hole pairs, resulting in less than ideal actual photocatalytic effects.

[0045] In recent years, transition metal dihalogen compounds (TMDs) have attracted widespread attention due to their unique layered structure, high stability, and excellent electronic and optoelectronic properties. Among them, MnS2, as a p-type semiconductor, has a wide bandgap and is widely used in optical storage and high-capacity memory, solar selective coatings, and short-wavelength optoelectronic materials.

[0046] Therefore, this invention employs a strategy of combining MnS2 and LDH to develop a photocatalytic nanocomposite material that is simple to prepare, exhibits higher degradation rate of phenol under visible light, better stability, and is reusable, for catalytic activation of PMS to degrade phenol. Specific implementation details are as follows:

[0047] In a first aspect, the present invention provides a method for preparing ZnCoFe-LDH / MnS2 photocatalytic nanomaterials. Figure 1 A flowchart illustrating the preparation method of ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided in this embodiment of the invention is shown, as follows: Figure 1 As shown, the method includes the following preparation steps:

[0048] Step 1: Disperse ZnCoFe-LDH powder in a certain amount of deionized water to form a suspension with a ZnCoFe-LDH concentration of 2-3 g / L;

[0049] Step 2: Add a first mixed solution containing thiourea and MnCl2·4H2O in a molar ratio of 2:1 to the suspension, and mix well to form the first solid-liquid blend;

[0050] Step 3: Transfer the first solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out the first hydrothermal reaction at 180-200℃. Collect the solid product after the reaction is completed by centrifugation, and then wash and vacuum dry it to obtain ZnCoFe-LDH / MnS2 photocatalytic nanomaterials.

[0051] In practice, ZnCoFe-LDH powder can be commercially available or prepared in-house. First, the ZnCoFe-LDH powder is dispersed in a certain amount of deionized water to form a suspension. To ensure uniform dispersion, ultrasonic dispersion for 30-60 minutes is used. Then, thiourea and MnCl2·4H2O are dissolved in deionized water to form a first mixed solution, which is added to the suspension. The mixture is stirred vigorously for 2-3 hours to ensure complete mixing. The solution is then transferred to a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and subjected to a first hydrothermal reaction at 180-200°C. After 20-24 hours, the reaction product is washed and vacuum dried to obtain ZnCoFe-LDH / MnS2 photocatalytic nanomaterials. During the first hydrothermal reaction, the solution-state thiourea and MnCl2·4H2O are converted into MnS2 spherical nanoparticles at high temperature, which are uniformly distributed on the surface and in the gaps of the ZnCoFe-LDH sheet structure. It can be assumed that the ZnCoFe-LDH sheets are used as templates modified by MnS2.

[0052] The present invention provides a method for preparing ZnCoFe-LDH / MnS2 photocatalytic nanomaterials. Through in-situ hydrothermal synthesis, ZnCoFe-LDH and MnS2 are successfully combined to form a new ZnCoFe-LDH / MnS2 photocatalytic nanomaterial. The addition of MnS2 causes a redshift in the UV-vis of ZnCoFe-LDH, resulting in a wider visible light absorption range for the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial compared to ZnCoFe-LDH alone. Furthermore, the introduction of MnS2 successfully enables the separation of photogenerated electron-hole pairs at the heterojunction (ZnCoFe-LDH and MnS2), thus avoiding the rapid in-situ recombination of electrons and holes in the band gap of a single ZnCoFe-LDH catalytic nanomaterial, which facilitates the separation of photogenerated carriers and the narrowing of the band gap.

[0053] In some embodiments, the washing process mentioned in step 3 includes: washing with deionized water and ethanol alternately 6-10 times; vacuum drying at a temperature of 60-80°C; and vacuum drying for 12-24 hours.

[0054] In some embodiments, self-made ZnCoFe-LDH can also be used to prepare the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials in steps 1-3 above. Specifically, Figure 2 A flowchart illustrating the preparation method of the ZnCoFe-LDH photocatalytic material provided in this embodiment of the invention is shown, as follows: Figure 2 As shown, ZnCoFe-LDH can be prepared by the following steps:

[0055] Step 11: Dissolve Zn(NO3)2·6H2O, Co(NO3)2·6H2O and Fe(NO3)3·9H2O in deionized water to form Zn 2+ Co 2+ with Fe 3+ The molar ratio is [M] 2+ ] / [M 3+ A precursor solution with a ratio of 2:1;

[0056] Step 12: Add the precursor solution dropwise to a second mixed solution containing NaOH and Na2CO3 in a molar ratio of (2-3):1, and stir vigorously at 60-90℃ for 2-3 hours to form the second solid-liquid blend.

[0057] Step 13: Transfer the second solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out the second hydrothermal reaction at 110-120℃. Collect the solid precipitate after the reaction is completed by centrifugation, and then wash and vacuum dry it to obtain ZnCoFe-LDH powder.

[0058] In practice, after mixing the precursor solution and the second mixed solution, the mixture is stirred vigorously at 60-90℃ for 2-3 hours to allow the Zn... 2+ Co 2+ and Fe 3+ The product is converted into a hydroxide form, and a small amount of flocculent hydroxide precipitate is uniformly dispersed in the second solid-liquid blend under vigorous stirring. During the subsequent second hydrothermal reaction, the reaction temperature of the second solid-liquid blend is controlled at 110-120℃ and the time is 20-24h. After the reaction is completed, the reaction product is washed and vacuum dried to obtain ZnCoFe-LDH.

[0059] In some embodiments, the washing process mentioned in step 13 includes: washing with deionized water and ethanol alternately 6-10 times; vacuum drying at a temperature of 60-80°C; and vacuum drying for 12-24 hours.

[0060] In a second aspect, the present invention provides a ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by the preparation method of the first aspect described above.

[0061] This invention successfully prepared a ZnCoFe-LDH / MnS2 photocatalytic nanomaterial via in-situ hydrothermal synthesis, capable of efficiently and stably activating PMS to degrade phenol in water under visible light. Studies show that the introduction of MnS2 improves the visible light absorption range of the ZnCoFe-LDH photocatalyst and facilitates the separation of photogenerated carriers and the narrowing of the band gap. The simple preparation method and excellent photocatalytic performance make this catalyst an effective material for purifying phenol-containing wastewater.

[0062] Thirdly, the present invention provides an application of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by the preparation method of the first aspect above. The ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is used for visible light catalytic activation of persulfate to degrade phenol in wastewater to be treated.

[0063] In the wastewater to be treated, the initial concentration of ZnCoFe-LDH / MnS2 photocatalytic nanomaterial was 100 mg / L, the initial concentration of phenol was 10 mg / L, and the concentration of persulfate was 0.1 mM. Under visible light irradiation, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial photocatalytically activated persulfate, and the degradation efficiency of phenol reached 100% within 60 min.

[0064] The ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided by this invention have been experimentally proven to be effective in treating wastewater with the same dosage of ZnCoFe-LDH / MnS2, single ZnCoFe-LDH, and single MnS2 (initial concentration of 100 mg / L), the same phenol content in the wastewater (initial concentration of 30 ppm), the same initial PMS concentration (0.1 mM), and at room temperature. Under two standard solar intensities (2000 mW / cm²), the results were satisfactory. 2 Under visible light (λ>400nm) irradiation, ZnCoFe-LDH / MnS2 photocatalytic nanomaterials, single ZnCoFe-LDH, and single MnS2 were used to catalyze the degradation of phenol in wastewater by PMS. Due to the limited absorbance of single ZnCoFe-LDH, the degradation efficiency of phenol by PMS was only 16% within 30 minutes. Although single MnS2 has good absorbance, its high photogenerated electron-hole recombination rate resulted in a degradation efficiency of 55% for phenol by PMS within 60 minutes. In contrast, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided in this embodiment achieved a degradation efficiency of 100% for phenol within 60 minutes. Compared to single ZnCoFe-LDH photocatalytic nanomaterials, ZnCoFe-LDH / MnS2 photocatalytic nanomaterials have a wider visible light absorption range and a more efficient ability to activate PMS for phenol degradation.

[0065] Furthermore, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials provided by this invention maintained a 100% efficiency in catalytically activating PMS to degrade phenol in three consecutive degradation experiments, with no significant loss in degradation rate. This demonstrates that the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials have good stability, can be recycled, and have potential application value in the field of air purification.

[0066] To enable those skilled in the art to better understand the present invention, the following embodiments are provided to illustrate in detail the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial, its preparation method, and its application.

[0067] Unless otherwise specified, all reagents and other instruments used in the following examples and experiments are commercially available products. All reagents are ready to use without further purification. Deionized water was used in all experiments.

[0068] Example 1: Preparation of ZnCoFe-LDH / MnS2 photocatalytic nanomaterials

[0069] Step 1: Dissolve 0.595 g Zn(NO3)2·6H2O, 0.582 g Co(NO3)2·6H2O, and 0.808 g Fe(NO3)3·9H2O in 50 mL of deionized water to obtain a precursor solution. Then, add this solution dropwise to a solution containing 0.384 g NaOH and 0.424 g Na2CO3 under vigorous stirring, and stir continuously and vigorously at 70 °C for 3 h. Transfer the resulting mixture to a stainless steel autoclave lined with polytetrafluoroethylene (PTFE), and hydrothermally react at 110 °C for 24 h. After naturally cooling to room temperature, collect the solid precipitate by centrifugation, wash alternately with deionized water and ethanol until neutral, and vacuum dry at 60 °C for 24 h to obtain ZnCoFe-LDH powder.

[0070] Step 2: Place 0.1g of ZnCoFe-LDH powder in 40mL of deionized water and sonicate for 1h to ensure complete dispersion. Then, dissolve 0.457g of thiourea and 0.539g of MnCl2·4H2O in 20mL of deionized water and add to the ZnCoFe-LDH suspension. Stir vigorously at room temperature for 3h. Transfer the resulting mixture to a stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally react at 180℃ for 24h. After naturally cooling to room temperature, centrifuge to obtain a black product. Wash alternately with deionized water and ethanol 6-10 times, and vacuum dry at 60℃ for 24h to obtain ZnCoFe-LDH / MnS2 powder.

[0071] Comparative Example 1: Preparation of ZnCoFe-LDH

[0072] 0.595 g Zn(NO3)2·6H2O, 0.582 g Co(NO3)2·6H2O, and 0.808 g Fe(NO3)3·9H2O were dissolved in 50 mL of deionized water to obtain a precursor solution. This solution was then added dropwise to a solution containing 0.384 g NaOH and 0.424 g Na2CO3 under vigorous stirring, and the mixture was continuously and vigorously stirred at 70 °C for 3 h. The resulting mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and subjected to hydrothermal reaction at 110 °C for 24 h. After natural cooling to room temperature, the solid precipitate was collected by centrifugation, washed alternately with deionized water and ethanol until neutral, and then vacuum dried at 60 °C for 24 h to obtain ZnCoFe-LDH powder.

[0073] Comparative Example 2: Preparation of MnS2

[0074] 0.457 g of thiourea and 0.539 g of MnCl2·4H2O were dissolved in 50 mL of deionized water and stirred vigorously at room temperature for 3 h. The resulting mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally reacted at 180 °C for 24 h. After naturally cooling to room temperature, the solid was centrifuged to obtain a black solid, which was washed alternately with deionized water and ethanol 6-10 times and dried under vacuum at 60 °C for 24 h to obtain MnS2 powder.

[0075] Figure 3 The SEM image of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided in the embodiments of the present invention is shown, as follows: Figure 3 The ZnCoFe-LDH / MnS2 material shown is grown from dispersed MnS2 nanoparticles on an LDH sheet structure. ZnCoFe-LDH is the sheet structure, and MnS2 is the nanosphere structure. It can be seen that the ZnCoFe-LDH sheets act as a template modified by MnS2.

[0076] Figure 4 The ultraviolet diffuse reflectance spectra of the photocatalytic nanomaterials provided in the embodiments and comparative examples of the present invention are shown. Figure 4 As shown, the light absorption edge of the ZnCoFe-LDH photocatalyst provided in Comparative Example 1 is around 650 nm, while the optical absorption of MnS2 provided in Comparative Example 2 covers the entire visible spectrum, indicating that it can utilize more visible light. Through the combination of the two, the light absorption range of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial still covers the entire visible spectrum, indicating that it can utilize sufficient solar energy.

[0077] Figure 5 The following is an illustration of the N2 adsorption-desorption isotherm of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided in this embodiment of the invention. Figure 5 As shown, the specific surface area of ​​the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is 132.2187 m². 2 / g. Due to the interlayer diffusion of CO3 in ZnCoFe-LDH. 2- The intercalation connection increases the interlayer spacing, giving the photocatalytic composite material a larger specific surface area, which provides more adsorption and active sites for photocatalytic reactions.

[0078] Furthermore, to investigate the composition and structure of the catalytic nanomaterials provided in the examples and comparative examples, FTIR analysis was employed. Figure 6 The Fourier diffuse reflectance infrared spectra of the catalytic nanomaterials provided in the embodiments and comparative examples of the present invention are shown. Figure 6 As shown, for the ZnCoFe-LDH provided in Comparative Example 1, at 3441 cm⁻¹ -1The nearby absorption peak is attributed to the OH stretching mode of interlayer water molecules and hydroxyl groups; at 1506 cm⁻¹ -1 and 1385cm -1 The nearby absorption peak is attributed to interlayer CO3. 2- v3 mode; 1047cm -1 and 833cm -1 The peaks at these locations belong to interlayer CO3. 2- ν1 and ν2 patterns; 600–400 cm -1 The absorption peak in the band may be attributed to the stretching mode of the metal-oxygen groups. For MnS2 provided in Comparative Example 2, the absorption peak at 700 cm⁻¹ is... -1 ~550cm -1 Characteristic peaks of MnS2 were observed nearby, which are attributed to the stretching vibration of S-Mn-S. For the ZnCoFe-LDH / MnS2 provided in Example 1, the main typical absorption peaks of both ZnCoFe-LDH and MnS2 are present in ZnCoFe-LDH / MnS2, further demonstrating the successful synthesis of the ZnCoFe-LDH / MnS2 catalytic nanomaterial in Example 1.

[0079] Experimental Example 1

[0080] This experimental example is used to verify the degradation performance of phenol by the ZnCoFe-LDH / MnS2 photocatalytic nanomaterials prepared in Example 1 under visible light.

[0081] Photocatalytic activity evaluation:

[0082] The photocatalytic activation of PMS for phenol degradation was carried out in a 250 mL quartz photochemical reactor. The initial concentration of the phenol solution was 10 mg / L (10 ppm), and the initial concentration of the photocatalyst was 100 mg / L. A 300 W xenon lamp with a filter (>420 nm) was used as the visible light source. The distance between the light source and the reactor was 10 cm. The light intensity was measured to be twice the solar intensity (2000 mW / cm²). 2 The catalyst sample (10 mg) and 100 mL of phenol solution (10 ppm) were added to the reactor. Before illumination, a dark adsorption treatment was performed for 30 min, followed by the addition of 0.1 mM PMS and the activation of the light source, with a reaction time of 30 min. During the photocatalytic reaction, 1 mL of solution was collected every 5 min and filtered through a 0.22 μm microporous filter to remove the photocatalyst. The solution was transferred to a high-performance liquid chromatography (HPLC) vial containing 0.5 mL of methanol as a terminator, and the phenol concentration was analyzed using an HPLC device equipped with a UV detector. The degradation rate of phenol was expressed as the equilibrium phenol concentration / initial phenol concentration C / C0.

[0083] Figure 7The diagram shows a comparison of the photocatalytic degradation performance of phenol by the photocatalytic nanomaterials provided in the embodiments and comparative examples of the present invention. It can be seen that, due to the limited absorbance of the pure ZnCoFe-LDH provided in Comparative Example 1, the degradation efficiency of phenol is only 16% within 30 minutes. While the pure MnS2 provided in Comparative Example 2 has good absorbance, its photogenerated electron-hole recombination rate is high, resulting in a degradation efficiency of 55% for phenol within 60 minutes. The ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by combining the two (provided in Example 1) achieves a 100% degradation efficiency of phenol within 60 minutes, demonstrating highly efficient PMS activation for phenol degradation under visible light.

[0084] Continuous degradation experiment:

[0085] After the first degradation reaction was completed, the photocatalyst was filtered and collected, dried at 60°C for 1 hour, and then put back into the reactor for the next phenol removal reaction. Except for the materials, the other reaction conditions were kept the same as the first time. After the second reaction was completed, the above steps were repeated to carry out the third degradation experiment.

[0086] Experimental results showed that under xenon lamp irradiation, with an initial phenol solution concentration of 10 ppm, an initial photocatalyst concentration of 100 mg / L, and an initial temperature of room temperature, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial provided in Example 1 achieved a 100% degradation efficiency of phenol after 30 minutes. No significant loss in phenol degradation rate was observed in each repeated cycle, indicating that the catalyst has good reusability.

[0087] Figure 8 The reusability experiment of the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial for phenol degradation provided in the embodiments of the present invention is shown. Figure 8 As shown, the removal rate of phenol did not show any significant loss in each repeated cycle, and the degradation rate did not decrease significantly after 3 cycles, indicating that the catalyst has high reusability.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0090] The foregoing has provided a detailed description of the ZnCoFe-LDH / MnS2 photocatalyst, its preparation method, and its applications. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing ZnCoFe-LDH / MnS2 photocatalytic nanomaterials, characterized in that, The method includes: Step 1: Disperse ZnCoFe-LDH powder in a certain amount of deionized water to form a suspension with a ZnCoFe-LDH concentration of 2-3 g / L; Step 2: Add a first mixed solution containing thiourea and MnCl2·4H2O in a molar ratio of 2:1 to the suspension, and mix well to form a first solid-liquid blend; Step 3: Transfer the solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out the first hydrothermal reaction at 180-200℃. Collect the solid product after the reaction by centrifugation, and then wash and vacuum dry it to obtain the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial.

2. The preparation method according to claim 1, characterized in that, In step 1, the dispersion is performed using ultrasound, and the ultrasonic dispersion time is 30-60 minutes.

3. The preparation method according to claim 1, characterized in that, In step 3, the first hydrothermal reaction is carried out for 20-24 hours.

4. The preparation method according to claim 1, characterized in that, In step 3, the washing process includes: washing with deionized water and ethanol alternately 6-10 times; The vacuum drying process is carried out at a temperature of 60-80℃ and for a duration of 12-24 hours.

5. The preparation method according to claim 1, characterized in that, The ZnCoFe-LDH was prepared by the following steps: Step 11: Dissolve Zn(NO3)2·6H2O, Co(NO3)2·6H2O and Fe(NO3)3·9H2O in deionized water to form Zn 2+ Co 2+ with Fe 3+ The molar ratio is [M] 2+ ] / [M 3+ A precursor solution with a ratio of 2:1; Step 12: Add the precursor solution dropwise to a second mixed solution containing NaOH and Na2CO3 in a molar ratio of (2-3):1, and stir vigorously at 60-90℃ for 2-3 hours to form the second solid-liquid blend. Step 13: Transfer the second solid-liquid blend to a stainless steel autoclave lined with polytetrafluoroethylene, and carry out a second hydrothermal reaction at 110-120°C. Collect the solid precipitate after the reaction is completed by centrifugation, and then wash and vacuum dry it to obtain the ZnCoFe-LDH powder.

6. The preparation method according to claim 5, characterized in that, In step 13, the second hydrothermal reaction is carried out for 20-24 hours.

7. The preparation method according to claim 5, characterized in that, In step 13, the washing process includes washing with deionized water and ethanol alternately 6-10 times.

8. The preparation method according to claim 5, characterized in that, In step 13, the temperature of the vacuum drying process is 60-80℃; the time of the vacuum drying process is 12-24h.

9. A ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by the preparation method according to any one of claims 1-8.

10. The application of a ZnCoFe-LDH / MnS2 photocatalytic nanomaterial obtained by any one of the preparation methods according to claims 1-8, characterized in that, The ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is used for visible light photocatalytic activation of persulfate to degrade phenol in wastewater to be treated; In the wastewater to be treated, the initial concentration of ZnCoFe-LDH / MnS2 photocatalytic nanomaterial is 100 mg / L, the initial concentration of phenol is 10 mg / L, and the concentration of persulfate is 0.1 mM. Under visible light irradiation, the ZnCoFe-LDH / MnS2 photocatalytic nanomaterial photocatalytically activates the persulfate, and the degradation efficiency of phenol can reach 100% within 60 min.

Images