Fe3o4 / p / cuo x Nano-array composite photocatalyst, preparation method and application thereof

Abstract

The application relates to the technical field of photocatalysts, in particular to a Fe3O4 / P / CuO x Nano-array composite photocatalyst, preparation method and application thereof. The preparation method is as follows: S1, a copper base material with CuO x nano-arrays is prepared; S2, the copper base material obtained in step S1 is immersed in a protective layer growth solution, the base material is taken out after reaction, and then washed and dried; the protective layer growth solution is prepared from one or more of dopamine mixed solution, tannic acid mixed solution and tea polyphenol mixed solution; S3, the base material obtained in step S2 is immersed in Fe3O4 nanoparticle dispersion liquid for a period of time, and then washed and dried after being taken out, so that the composite photocatalyst is prepared. Under visible light irradiation, the adsorption rate of the application to Cr(VI) reaches more than 98%, the proportion of elemental Cr in the reduction product is more than 60%, and the decomposition rate of the antibiotic reaches more than 99%.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photocatalysts, in particular to a Fe3O4 / P / CuO x Nano array composite photocatalyst, preparation method and application thereof. BACKGROUND

[0002] Heavy metal pollution and antibiotic pollution in water sources have become global pollution problems that need to be solved urgently. Chromium is one of the five key heavy metal pollutants in wastewater, mainly existing in the form of Cr(III) and Cr(VI). Cr(VI) is about 100 times more toxic than Cr(III) and is not easy to degrade under natural conditions. At present, common removal methods for Cr(VI) and antibiotics include membrane separation, adsorption, chemical precipitation, electrolysis and photocatalytic degradation. However, most of the removal studies only focus on the removal effect of a single pollutant in water, and only a small number of studies report the application of adsorption in antibiotic and heavy metal composite pollution. Among them, adsorption and photocatalytic degradation are widely used in the removal of Cr(VI) and antibiotics. However, adsorption is widely used due to its low cost and high efficiency, but adsorption only plays a fixing role, and Cr(VI) still has potential threats. Semiconductor-based photocatalytic technology can achieve the reduction of Cr(VI) and is considered a new green technology. Existing photocatalytic reduction can effectively reduce Cr(VI) to Cr(III), but Cr(III) may be oxidized again in the aquatic environment. Zero-valent chromium (Cr(0)) as the most stable reduced state has the characteristics of non-toxicity and inertness, and can achieve the complete harmlessness of Cr(VI). Only by further reducing Cr(III) to Cr(0) can the purpose of harmless treatment of industrial wastewater containing Cr(VI) be achieved. In view of the shortcomings of the existing materials, it is urgent to develop a composite material that can deeply reduce Cr(VI) to Cr(0) and simultaneously remove antibiotics.

[0003] The water-sliding-lithium-based Bi2O2CO3 / MgAlBi-LDHs adsorption-photocatalytic composite material described in the existing patent "A composite environmental purification material and a preparation method thereof (CN117753455A)" can synergistically degrade Cr(VI) and tetracycline TC (a typical antibiotic) under visible light excitation, so that Cr(VI) is reduced to low-toxicity Cr(III), further improving the removal capacity of Cr(VI) and TC. However, the hydrotalcite powder used in the preparation technology is easy to cause secondary pollution, and it is difficult to recover. In addition, Cr(III) also has certain toxicity, and there is still a threat of Cr elements to the environment.

[0004] The biochar-based CoFe2O4 / Fe2O3 composite heterojunction structure described in the prior art "Construction of CoFe2O4 / Fe2O3 S-type heterojunctions on biochar for activating peroxymonosulfate towards simultaneous removal of TC and Cr (VI) (Separation and Purification Technology 354 (2025) 129157)" can effectively remove Cr(VI) and TC under visible light irradiation. However, this preparation technology is still based on biomass powder raw materials, and also has the problems of difficult recovery and easy secondary pollution. The problem of reducing Cr(VI) to elemental Cr has not been solved. SUMMARY

[0005] The present application aims at the above-mentioned deficiencies of the prior art, and proposes a Fe3O4 / P / CuO x Nanometer array composite photocatalyst and its preparation method and application.

[0006] The first object of the present application is to provide a Fe3O4 / P / CuO x Preparation method of nanometer array composite photocatalyst, comprising the following steps: S1, preparing a copper base material with CuO x Nanometer array growing on the surface of the copper base material;

[0007] S2, immersing the copper base material obtained in step S1 into a protective layer growth solution, taking out the base material after the reaction, and washing and drying; the protective layer growth solution is prepared from one or more of dopamine mixed solution, tannic acid mixed solution and tea polyphenol mixed solution;

[0008] S3, immersing the base material obtained in step S2 in Fe3O4 nanoparticle dispersion liquid for a period of time, washing and drying after taking out, to obtain Fe3O4 / P / CuO x Nanometer array composite photocatalyst.

[0009] Further, the specific operation of step S1 is: the copper base material is repeatedly cleaned with ethanol and deionized water under ultrasonic, then the copper base material is immersed in an alkali treatment liquid, reacted at a temperature of-5~50℃ for 10-60min, the copper base material is taken out, washed and dried, and heat treated at a temperature of 100-500℃ for 1-120min, to obtain a copper base material with uniformly distributed CuO x Nanometer array growing on the surface of the copper base material.

[0010] Further, in step S1, the alkali treatment liquid is a mixed solution of alkali, persulfate solution and ammonia water, and the molar ratio of alkali, persulfate solution and ammonia water in the alkali treatment liquid is 1:(0.1-1):(0.05-0.5), wherein the alkali and the persulfate solution are both calculated according to metal ions; the alkali is one or both of sodium hydroxide solution and potassium hydroxide solution, and the persulfate solution is one or both of ammonium persulfate solution, sodium persulfate solution and potassium persulfate solution.

[0011] Further, in step S2, the reaction is carried out under a sealed condition at a temperature of-5-50℃ for 2-24h to obtain CuO with firm combination. x The copper substrate of the nano array.

[0012] Further, in step S2, the dopamine mixed solution is mixed by Tris-HCl 10-40 mmol / L buffer solution and 5-20 mmol / L dopamine hydrochloride, and the pH is 8-9.

[0013] The tannic acid mixed solution is mixed by 1-10 mmol / L tannic acid solution, 5-20 mmol / L FeCl3 solution and 0.01-0.1 mol / L NaOH solution, and the pH is 8-10.

[0014] The tea polyphenol mixed solution is mixed by 0.3-3g / L tea polyphenol solution and 0.01-0.1 mol / L NaOH solution, and the pH is 8-10.

[0015] Further, in step S3, the immersion temperature is-5-50℃, and the time is 0.5-6h; the drying temperature is 50-70℃, and the time is 1-2h.

[0016] Further, in step S3, the concentration of the Fe3O4 nanoparticle dispersion liquid is 0.001-1 g / L, and the particle size of Fe3O4 in the dispersion liquid is 10-150 nm.

[0017] Further, the copper substrate is one or more of foamed copper, copper mesh and copper sheet.

[0018] The second object of the present application is to provide a Fe3O4 / P / CuO x Nano array composite photocatalyst.

[0019] The third object of the present application is to provide a Fe3O4 / P / CuO x Application of the nano array composite photocatalyst, characterized by being used for catalytic reduction of Cr(VI) and degradation of antibiotics, wherein the product of catalytic reduction of Cr(VI) contains nano metal Cr.

[0020] The Fe3O4 / P / CuO x The nano array composite photocatalyst is a nanorod structure, and is regular and orderly, which is prepared on a copper base x The nano array is then protected and fixed by attaching a protective layer thereon, and Fe3O4 nanoparticles are loaded on the protective layer to prevent the formation of a heterojunction structure between copper oxide and ferrite, and the structure can effectively utilize solar energy, quickly generate and separate electron holes, and the generated electron holes can be effectively migrated to the material surface to deeply reduce Cr(VI) to Cr(0), and can also synchronously decompose antibiotics and microorganisms.

[0021] The specific surface area of the foamed copper material is significantly increased, the absorption and utilization of visible light are enhanced, and the CuO x The nano array and the tip effect of the ferrite fine particles not only further enhance the absorption and utilization of visible light, but also reduce the recombination of photoelectron hole pairs at the interface, promote the separation and migration of carriers, and have good photocatalytic reduction and degradation capacity for Cr(VI) and antibiotics, and have a wide application prospect in the treatment of waste liquid containing heavy metals and antibiotics. Under visible light irradiation, the adsorption rate of Cr(VI) reaches more than 98%, and the decomposition rate of antibiotics reaches more than 99%; through analysis, after visible light irradiation for 2h, the proportion of elemental Cr in the Cr(VI) reduction product of the prepared photocatalytic material is more than 60%, since the XPS detection depth is 2-3nm, and the metal Cr is easy to form a 2-3nm Cr2O3 passivation film on the surface, thus reasoning that one of the sources of Cr(III) is the Cr2O3 passivation film on the surface of elemental Cr, and the proportion of elemental Cr is higher than the detection data 60%, therefore, the photocatalytic reduction technology of Cr(VI) to elemental Cr can significantly reduce the threat of Cr(VI) and Cr(III) to the environment.

[0022] The preparation process of the application can be carried out at room temperature, the production process is simple, the energy consumption is small, the required instrument equipment investment is small, the raw material price is low, the utilization rate is high, there is no environmental pollution, and it is suitable for batch production. x The Fe3O4 / P / CuO BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the surface EDS spectrum of the sample obtained in Example 1 after photocatalytic reduction of Cr(VI) (a); and the XPS fine spectrum valence state analysis of the Cr element on the surface of the reduced sample (b);

[0024] Figure 2TEM images of the sample obtained in Example 1 after photocatalytic reduction of Cr(VI) (a); HR-TEM image of surface Cr(0) nanoparticles (b);

[0025] Figure 3 XPS fine spectrum valence state analysis of iron element on the catalyst before and after photocatalytic reduction of Cr(VI) (a); XPS fine spectrum valence state analysis of copper element (b)

[0026] Figure 4 is the VSM image of the Fe3O4nanoparticles used in Example 1;

[0027] Figure 5 is the photocatalytic reduction rate curve of the samples prepared in Example 1 and Comparative Example 1 against 30 mg / L Cr(VI);

[0028] Figure 6 is the photocatalytic reduction rate curve (with light) and adsorption rate curve (without light) of the samples prepared in Example 3 and Comparative Example 1 against 50 mg / L Cr(VI);

[0029] Figure 7 are the surface morphologies of the samples prepared in Example 1 and Comparative Example 2 before and after the cycle test; 7a is the SEM image of the sample obtained in Example 1, 7b is the SEM image of the sample after the cycle reaction, 7c is the SEM image of the sample prepared in Comparative Example 2, and 7d is the SEM image of the sample prepared in Comparative Example 2 after the cycle reaction. DETAILED DESCRIPTION

[0030] The following are specific embodiments of the present application and further describe the technical solutions of the present application in combination with the accompanying drawings, but the present application is not limited to these embodiments.

[0031] To avoid repetition, the technical parameters involved in the present detailed description are described as follows: Fe3O4 / P / CuO x "P" in the composite structure refers to the protective layer formed on the CuO x nanoparticle array substrate after growth.

[0032] Tea polyphenol is a product available in the prior art, for example: McLean reagent tea polyphenol CAS No.: 84650-60-2.

[0033] Example 1

[0034] Copper substrate selection: copper mesh is selected as the substrate.

[0035] Preparation of the alkaline treatment solution: a mixed solution of 0.01 mol / L NaOH, 0.005 mol / L (NH4)2S2O8, and 0.002 mol / L NH3·H2O.

[0036] Fe3O4 nanoparticle dispersion liquid preparation: the concentration of Fe3O4 nanoparticle dispersion liquid is 0.01 g / L, and the particle size of Fe3O4 in the dispersion liquid is 10 nm.

[0037] CuO x Nanometer array growth: the copper substrate is ultrasonically cleaned with ethanol and deionized water for 10 min, repeatedly three times, then the copper substrate is immersed in the alkali treatment liquid, reacted at a temperature of 20℃ for 40 min, the copper substrate is taken out, washed and dried, and heat treated at a temperature of 100℃ for 120 min, to obtain the CuO x Nanometer array copper substrate.

[0038] Protection treatment: the CuO x Nanometer array substrate is immersed in the protective layer growth solution, and the protective layer growth solution is prepared by mixing a tannic acid mixed solution and a tea polyphenol mixed solution at a volume ratio of 2:1. The tannic acid mixed solution is a mixture of 1 mmol / L tannic acid solution, 5 mmol / L FeCl3 solution and 0.01 mol / L NaOH solution, and the pH is 8. The tea polyphenol mixed solution is a mixture of 1 g / L tea polyphenol solution and 0.07 mol / L NaOH solution, and the pH is 10.

[0039] Under the sealed condition, the reaction is carried out at a temperature of-5℃ for 24h, and after the reaction is completed, the substrate is taken out, washed and dried to obtain the CuO x Nanometer array copper substrate.

[0040] Composite structure loading: the substrate obtained by the protection treatment is immersed in the Fe3O4 nanoparticle dispersion liquid, the temperature is-5℃, the time is 3h, and the substrate is taken out, washed and dried in an oven at 50℃ for 1-2h to obtain the Fe3O4 / P / CuO x Composite structure nanometer array copper substrate.

[0041] Example 2

[0042] In this example, the protective layer growth solution is prepared by mixing a dopamine mixed solution and a tea polyphenol mixed solution at a volume ratio of 3:1. The dopamine mixed solution is a mixture of Tris-HCl 20 mM buffer and 2 mg / mL dopamine hydrochloride, and the pH is 8.5. The tea polyphenol mixed solution is a mixture of 0.3 g / L tea polyphenol solution and 0.01 mol / L NaOH solution, and the pH is 8.

[0043] The other parts are the same as in Example 1.

[0044] Example 3

[0045] In this embodiment, the protective layer growth solution is prepared from a dopamine mixed solution; the dopamine solution is prepared from a Tris-HCl 40 mM buffer and 4 mg / mL dopamine hydrochloride mixed to a pH of 8.5.

[0046] The other is the same as example 1.

[0047] Comparative example 1

[0048] The Fe3O4 nanoparticles are not loaded, and the other is the same as example 1.

[0049] Comparative example 2

[0050] The process of example 1 is used to prepare a copper-based material with a uniform distribution of CuO x nanoparticle arrays on the surface.

[0051] Figure 1 is the EDS spectrum of the surface of the sample obtained in example 1 after photocatalytic reduction of Cr(VI) (a); and the XPS fine spectrum valence state analysis of the Cr element on the surface of the reduced sample (b).

[0052] Figure 1 (a) illustrates that after photocatalytic reduction of Cr(VI), there are nanoparticles containing Cr elements and content on the surface of the composite structure, Figure 1 (b) XPS characterization of the surface Cr element shows the presence of metallic Cr, proving that the material can photocatalytically reduce metallic Cr.

[0053] Figure 2 is the TEM image of the sample obtained in example 1 after reaction (a); and the HR-TEM image of the surface Cr(0) nanoparticles (b). Figure 2 The TEM characterization of (a) shows the microstructure of the material after reaction and metallic Cr, and it is clear that there is a protective layer on the surface of the material, which protects the nanowires and fixes the magnetite. It also shows that there is no heterojunction structure between copper oxide and magnetite.

[0054] Figure 2 (b) further characterizes the presence of metallic Cr nanoparticles by TEM.

[0055] Figure 3 is the XPS fine spectrum valence state analysis of the elements on the catalyst before and after photocatalytic reaction; from the figure, it can be seen that the valence states of Fe and Cu do not change significantly before and after photocatalytic reaction, indicating that the electron-hole pairs generated have been used to oxidize and reduce heavy metals and organic pollutants on the surface of the material.

[0056] Figure 4is the VSM graph of the Fe3O4 nanoparticles used in Example 1; it can be seen from the graph that the Fe3O4 nanoparticles used have strong magnetism, and the material can be separated from the solution by magnetic separation, providing convenient conditions for recycling the material. The Fe3O4 nanoparticles used above can be prepared by the method disclosed in CN117566807A.

[0057] Figure 5 is the photocatalytic reduction rate curve of the sample prepared in Example 1 and the product prepared in Comparative Example 1 on 30 mg / L Cr(VI); compared with the product prepared in Comparative Example 1, the Fe3O4 / P / CuO x nanoparticle array composite photocatalyst has higher photocatalytic reduction rate on Cr(VI). It is shown that the composite photocatalyst formed after loading Fe3O4 has good performance in photocatalytic reduction of Cr(VI).

[0058] Figure 6 is the photocatalytic reduction rate curve (with light) and the adsorption rate curve (without light) of the sample prepared in Example 3 on 50 mg / L Cr(VI).

[0059] Compared with the product prepared in Comparative Example 1, the Fe3O4 / P / CuO x nanoparticle array composite photocatalyst has higher photocatalytic reduction rate and adsorption rate on Cr(VI). It is shown that the composite photocatalyst formed after loading Fe3O4 has good performance in adsorption and photocatalytic reduction of Cr(VI).

[0060] The catalysts prepared in the examples and comparative examples and copper oxide were subjected to a cycle test of photocatalytic reduction of Cr(VI), Figure 7 are the surface morphologies of the samples prepared in Example 1 and Comparative Example 1 before and after the cycle test; 7a is the SEM graph of the sample obtained in Example 1, 7b is the SEM graph of the sample after 5 cycles of reaction; 7c is the SEM graph of the sample prepared in Comparative Example 2; 7d is the SEM graph of the sample prepared in Comparative Example 2 after the cycle reaction. It can be seen that the sample obtained in Example 1 has a protective layer, and the morphology and performance of the material remain stable after 5 cycles, while the surface morphology of the copper oxide nanowire prepared in Comparative Example 2 has completely collapsed after 5 cycles. Table 1 is the cycle test result table.

[0061] Table 1

[0062]

[0063] Table 2 is the sample of Example 1-3 immersed in a mixed solution of antibiotic and 30 mg / L Cr(VI) ions, when photocatalytic reduction of Cr(VI), the simultaneous photocatalytic degradation rate of tetracycline hydrochloride, norfloxacin, and the sample immersed in bacteria solution, photocatalytic antibacterial rate of E. coli and S. aureus after light irradiation.

[0064] Table 2

[0065]

[0066] The above not involved, applicable to the prior art.

[0067] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood that such examples are for illustration only and should not limit the scope of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them without departing from the direction of the present application or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modification, equivalent replacement, improvement, etc. made according to the technical essence of the present application to the above embodiments shall be included in the protection scope of the present application.

Claims

1. A Fe304 / P / CuO x A method for preparing a Fe304 / P / CuO The method comprises the following steps: S1, preparing a CuO surface growth x copper substrate of nanometer array S2, the copper base material obtained in step S1 is immersed in a protective layer growth solution, and the base material is taken out after the reaction, washed and dried; the protective layer growth solution is prepared from one or more of a dopamine mixed solution, a tannin acid mixed solution and a tea polyphenol mixed solution; S3, immersing the substrate obtained in step S2 in a dispersion liquid of Fe3O4 nanoparticles for a period of time, washing and drying after taking out, to obtain Fe3O4 / P / CuO x Nano-array composite photocatalyst.

2. The production method according to claim 1, wherein The specific operation of step S1 is: the copper substrate is repeatedly cleaned with ethanol and deionized water by ultrasonic, then the copper substrate is immersed in an alkaline treatment solution, reacted at a temperature of-5-50℃ for 10-60 min, the copper substrate is taken out, washed and dried, and heat treated at a temperature of 100-500℃ for 1-120 min, to obtain a copper substrate with uniformly distributed CuO grown on the surface x Copper substrate with nano array.

3. The production method according to claim 2, wherein In step S1, the alkali treatment liquid is a mixed solution of lye, persulfate solution and ammonia water, and the molar ratio of lye, persulfate solution and ammonia water in the alkali treatment liquid is 1:(0.1-1):(0.05-0.5), wherein the lye and the persulfate solution are both calculated according to metal ions; The lye is one or both of sodium hydroxide and potassium hydroxide solution, and the persulfate solution is one or both of ammonium persulfate, sodium persulfate and potassium persulfate solution.

4. The production method according to claim 1, wherein In step S2, under sealing condition, the reaction is carried out at a temperature of -5-50 ℃ for 2-24 h to obtain CuO with firm combination x Copper substrate of nano-array.

5. The production method according to claim 1, characterized by, In step S2, the dopamine mixed solution is mixed by Tris-HCl 10-40 mmol / L buffer solution and 5-20 mmol / L dopamine hydrochloride, and the pH is 8-9; The tannin acid mixed solution is mixed by 1-10 mmol / L tannin acid solution, 5-20 mmol / L FeCl3 solution and 0.01-0.1 mol / L NaOH solution, and the pH is 8-10; The tea polyphenol mixed solution is mixed by 0.3-3 g / L tea polyphenol solution and 0.01-0.1 mol / L NaOH solution, and the pH is 8-10.

6. The production method according to claim 1, characterized by, In step S3, the immersion temperature is-5~50℃, and the time is 0.5~6h; the drying temperature is 50℃~70℃, and the time is 1-2h.

7. The production method according to claim 1, characterized by, In step S3, the concentration of the Fe3O4 nanoparticle dispersion liquid is 0.001-1 g / L, and the particle size of Fe3O4 in the dispersion liquid is 10-150 nm.

8. The production method according to claim 1, wherein The copper base material is one or more of foamed copper, copper mesh and copper sheet.

9. Fe304 / P / CuO prepared by the method of any one of claims 1-8 x nanorod array composite photocatalyst.

10. A Fe304 / P / CuO nanorod array composite photocatalyst as claimed in claim 9. x The application relates to an application of a Fe3O4 / P / CuO nanorod array composite photocatalyst, characterized in that, The method is used for catalytic reduction of Cr(VI) and degradation of antibiotics, and the product of catalytic reduction of Cr(VI) contains nano metal Cr.

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