Bismuth formate-nickel aluminum layered double hydroxide composite material and preparation method and application thereof

Abstract

The invention discloses a bismuth oxyformate-nickel aluminum layered double hydroxide composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a solution I containing a bismuth source and a solution II containing nickel-aluminum layered double hydroxides, and carrying out a heating reaction at 120-140 DEG C to obtain the bismuth oxyformate-nickel-aluminum layered double hydroxide composite material. According to the composite material provided by the invention, by constructing a bismuth formate oxide and NiAl-LDH heterostructure, compounding of electron-hole pairs is inhibited, light-induced electron-hole pairs are effectively separated, the visible light response range of the material is enlarged, and compared with BiOCOOH, the photocatalytic performance is remarkably improved. In addition, the preparation method provided by the invention has the advantages of cheap and easily available raw materials, simple process, convenience in operation, no secondary pollution and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic semiconductor materials, and particularly relates to a bismuth oxalate - nickel - aluminum layered double - hydroxide composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Since the discovery of penicillin in 1940, thousands of antibiotics have been developed for the clinical treatment of infectious diseases, saving countless lives. However, the extensive use of antibiotics has led to their residues in the environment, posing potential risks to the ecosystem and human health. Traditional treatment methods have limited effects on low - concentration and refractory antibiotics. The semiconductor photocatalytic oxidation technology has become a research hotspot due to its mild reaction conditions, ability to deeply mineralize pollutants, and utilization of solar energy. It is expected to efficiently degrade antibiotics under mild conditions, achieve environmental purification, provide a new way to solve the problem of antibiotic pollution, and has important application prospects and research value in the field of environmental remediation.

[0003] Bismuth oxalate (BiOCOOH) is a new type of semiconductor material with a fluorite - like layered structure. Its unique crystal structure and electronic properties effectively inhibit the recombination of photo - generated carriers, thereby enhancing its photo - activity. However, due to its relatively wide bandgap, its ability to respond to visible light is weak, which severely limits its application as a photocatalyst. Therefore, in order to improve the photocatalytic performance of BiOCOOH, it is necessary to modify BiOCOOH to improve its photocatalytic activity. Summary of the Invention

[0004] Aiming at the above - mentioned technical problems, the present invention provides a bismuth oxalate - nickel - aluminum layered double - hydroxide composite material, a preparation method thereof, and an application thereof. By constructing a heterostructure of bismuth oxalate and NiAl - LDH, the present invention effectively separates photo - induced electron - hole pairs, increases the visible - light response range of the material, improves the photocatalytic performance, and at the same time improves the treatment and degradation effect of the composite catalyst on antibiotics in water.

[0005] To achieve the above object, the present invention provides the following technical solutions;

[0006] On the one hand, the present invention provides a preparation method of a bismuth oxalate - nickel - aluminum layered double - hydroxide composite material, comprising the following steps:

[0007] Mix a solution I containing a bismuth source and a solution II containing nickel - aluminum layered double - hydroxide (NiAl - LDH), and then carry out a heating reaction at 120 - 140 °C to obtain the bismuth oxalate - nickel - aluminum layered double - hydroxide composite material.

[0008] As a preferred embodiment, the preparation method of the nickel - aluminum layered double - hydroxide comprises the following steps:

[0009] The nickel source and the aluminum source are subjected to a hydrothermal reaction under the action of hexamethylenetetramine;

[0010] Preferably, the nickel source is a soluble nickel salt, such as nickel nitrate hexahydrate; the aluminum source is a soluble aluminum salt, such as aluminum nitrate nonahydrate;

[0011] Preferably, the molar ratio of nickel in the nickel source to aluminum in the aluminum source is 0.5-2:1;

[0012] Preferably, the molar ratio of hexamethylenetetramine to nickel in the nickel source is 1-4:1;

[0013] Preferably, the time of the hydrothermal reaction is 6-8 h;

[0014] Preferably, the hydrothermal reaction further includes post-treatments of washing and drying; the drying is carried out at 60-80 °C for 12-18 h;

[0015] In some specific embodiments, the preparation method of the nickel-aluminum layered double hydroxide includes: dissolving the nickel source and the aluminum source in water, adding hexamethylenetetramine and stirring for 1-2 h, and then carrying out a hydrothermal reaction.

[0016] As a preferred embodiment, the solvent of Solution I is N,N-dimethylformamide;

[0017] Preferably, the solvent of Solution II is water;

[0018] Preferably, the time of the heating reaction is 12-14 h;

[0019] Preferably, after the heating reaction, it further includes post-treatments of washing and drying; the drying is carried out at 60-80 °C for 12-18 h;

[0020] Preferably, the mass ratio of bismuth in the bismuth source to the nickel-aluminum layered double hydroxide is 1.8-4:1.

[0021] On the other hand, the present invention provides a bismuth oxalate-nickel-aluminum layered double hydroxide composite material obtained by the above preparation method.

[0022] On the other hand, the present invention provides the use of the above bismuth oxalate-nickel-aluminum layered double hydroxide composite material as a photocatalyst.

[0023] Preferably, it is used for degrading tetracycline as a photocatalyst.

[0024] Advantages of the present invention: The bismuth oxalate - nickel - aluminum layered double - hydroxide composite material provided by the present invention inhibits the recombination of electron - hole pairs by constructing a heterostructure of bismuth oxalate and NiAl - LDH, effectively separates photo - induced electron - hole pairs, increases the visible - light response range of the material, and significantly improves the photocatalytic performance compared with BiOCOOH. In addition, the preparation method provided by the present invention has the advantages of inexpensive and easily available raw materials, simple process, convenient operation and no secondary pollution, etc. Brief Description of the Drawings

[0025] Figure 1 are the XRD patterns of BiOCOOH, NiAl - LDH, B / NA - 1 to 4 prepared in Comparative Example 1 and Examples of the present invention;

[0026] Figure 2 is the EDS pattern of B / NA - 3 prepared in Example 3 of the present invention;

[0027] Figure 3 are the SEM patterns of BiOCOOH, NiAl - LDH, B / NA - 3 prepared in Comparative Example 1 and Examples of the present invention;

[0028] Figure 4 is the tetracycline degradation curve in the effectiveness example of the present invention;

[0029] Figure 5 is the degradation kinetic curve of tetracycline in the effectiveness example of the present invention. Detailed Description of the Invention

[0030] The following examples are only a part of the examples of the present invention, rather than all of the examples. Therefore, the detailed description of the examples of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected examples of the present invention. All other examples obtained by those skilled in the art based on the examples of the present invention without creative efforts fall within the protection scope of the present invention.

[0031] In the present invention, unless otherwise specified, all devices and raw materials can be purchased from the market or are commonly used in this industry. The methods in the following examples, unless otherwise specified, are conventional methods in this field.

[0032] Example 1

[0033] The preparation process of the bismuth oxalate - nickel - aluminum layered double - hydroxide composite material in this example is as follows:

[0034] Step (1) Preparation of nickel - aluminum layered double - hydroxide (NiAl - LDH):

[0035] Dissolve nickel nitrate hexahydrate (1.687 g) and aluminum nitrate nonahydrate (2.181 g) in 40 mL of deionized water to form a green solution; add 2.453 g of hexamethylenetetramine and stir vigorously for 1.0 h; place it in a sealed Teflon-lined autoclave at 190 °C and treat for 6 h; after natural cooling, wash the green precipitate with water several times and dry it at 60 °C for 12 h to obtain nickel-aluminum layered double hydroxide (NiAl-LDH).

[0036] Step (2) Preparation of bismuth oxalate formate-nickel aluminum layered double hydroxide composite material:

[0037] Under ultrasonic conditions, disperse bismuth nitrate pentahydrate (0.825 g) uniformly in 8.5 mL of N,N-dimethylformamide to form solution A; disperse 0.125 g of the NiAl-LDH prepared in step (1) uniformly in 66.5 mL of deionized water to form solution B;

[0038] Add solution B to solution A and stir for 0.5 h; transfer the uniformly stirred solution to a 100 mL stainless steel reaction kettle with a PTFE lining and place it in an oven, and react at 120 °C for 12 h;

[0039] After the reaction is completed, cool to room temperature, take out the reactants, centrifuge to collect the obtained precipitate, wash it 3 times alternately with deionized water and absolute ethanol, and place the washed solid in an oven and dry it at 60 °C for 12 hours to obtain bismuth oxalate formate-nickel aluminum layered double hydroxide composite material (BiOCOOH / NiAl-LDH), denoted as B / NA-1.

[0040] Example 2

[0041] In this example, the preparation process of the bismuth oxalate formate-nickel aluminum layered double hydroxide composite material B / NA-2 is the same as that of Example 1, except that in step (3), the mass of the nickel aluminum layered double hydroxide is 0.175 g.

[0042] Example 3

[0043] In this example, the preparation process of the bismuth oxalate formate-nickel aluminum layered double hydroxide composite material B / NA-3 is the same as that of Example 1, except that in step (3), the mass of the nickel aluminum layered double hydroxide is 0.225 g.

[0044] Example 4

[0045] In this example, the preparation process of the bismuth oxalate formate-nickel aluminum layered double hydroxide composite material B / NA-4 is the same as that of Example 1, except that in step (3), the mass of the nickel aluminum layered double hydroxide is 0.275 g.

[0046] In this example, the mass ratio of bismuth oxalate formate to nickel-aluminum layered double hydroxide is 100:55.

[0047] Comparative Example 1

[0048] This comparative example provides a bismuth methylformate (BiOCOOH) material, and the preparation process is as follows:

[0049] Under ultrasonic conditions, bismuth nitrate pentahydrate (0.825 g) was uniformly dispersed in 8.5 mL of N,N-dimethylformamide; 66.5 mL of deionized water was added and stirred for 0.5 h; the obtained uniform solution was transferred to a 100 mL stainless steel reactor lined with polytetrafluoroethylene and placed in an oven, and reacted at 120 °C for 12 h; after the reaction, it was cooled to room temperature, and the obtained precipitate was collected by centrifugation after taking out the reactant, washed alternately with deionized water and absolute ethanol 3 times, and the washed solid was placed in an oven and heated at 60 °C for 12 hours, and the dried reactant was ground to obtain a bismuth methylformate (BiOCOOH) material.

[0050] Figure 1 XRD patterns of the bismuth oxalate formate (BiOCOOH) material, nickel-aluminum layered double hydroxide (NiAl-LDH), and bismuth oxalate formate-nickel-aluminum layered double hydroxide composites (B / NA-1, B / NA-2, B / NA-3, B / NA-4) prepared in Comparative Example 1 and Examples 1 to 4 of the present invention. It can be seen from the figure that the diffraction peaks of BiOCOOH are basically consistent with the standard card (JCPDS NO.35-0939), and there are no diffraction peaks of any impurity peaks, indicating that the obtained samples are all BiOCOOH. The diffraction peaks of NiAl-LDH are basically consistent with the standard card (JCPDS NO.22-0452), and there are no diffraction peaks of any impurity peaks, indicating that the obtained samples are all NiAl-LDH. B / NA-1, B / NA-2, B / NA-3, and B / NA-4 in the figure are the products obtained by the combination of BiOCOOH and NiAl-LDH. It can be seen from the figure that the crystal phases of BiOCOOH are all detected. As the loading amount of NiAl-LDH increases, the characteristic peaks of the (102) crystal plane change continuously, indicating that the uniform coating of NiAl-LDH restricts the crystal growth of BiOCOOH. In addition, no other impurity peaks appear in the BiOCOOH / NiAl-LDH composite sample, which means that the B / NA-1 to 4 composites are only composed of BiOCOOH and NiAl-LDH.

[0051] Figure 2EDS diagram of the bismuth oxalate-nickel aluminum layered double hydroxide composite material B / NA-3 prepared in Example 3 of the present invention. It can be seen from the figure that Bi, O, C, Al, and Ni elements are evenly distributed on the composite material, indicating the successful synthesis of the bismuth oxalate-nickel aluminum layered double hydroxide composite material.

[0052] Figure 3 SEM diagrams of the bismuth oxalate (BiOCOOH) material, nickel aluminum layered double hydroxide (NiAl-LDH), and bismuth oxalate-nickel aluminum layered double hydroxide composite materials B / NA-3 prepared in Comparative Example 1 and Examples of the present invention; among them, Figure 3 (a), (b), and (c) are SEM diagrams of the BiOCOOH material, NiAl-LDH material, and B / NA-3 respectively. It can be seen from the figure that both the BiOCOOH material and the NiAl-LDH material are nanosheet structures, while the bismuth oxalate-nickel aluminum layered double hydroxide composite material is a layered agglomerated structure with a large specific surface area.

[0053] In addition, from Figure 2 and Figure 3 it can be confirmed that the bismuth oxalate-nickel aluminum layered double hydroxide composite material synthesized in the present invention has a heterostructure.

[0054] Effect Example

[0055] The present invention tested the photocatalytic performance of the materials prepared in the above comparative examples and examples. The specific process is as follows:

[0056] Weigh 45 mg each of the bismuth oxalate (BiOCOOH) material, nickel aluminum layered double hydroxide (NiAl-LDH), and bismuth oxalate-nickel aluminum layered double hydroxide composite materials (B / NA-1, B / NA-2, B / NA-3, B / NA-4), and add them to 50 mL of tetracycline aqueous solution (tetracycline concentration is 20 mg / L) respectively; stir magnetically for 30 minutes under dark conditions to make the system reach adsorption-desorption equilibrium; then turn on the light source and carry out photocatalytic reaction under visible light with a wavelength of 380 - 780 nm. The total duration of the photocatalytic reaction is 120 minutes; take samples every 20 minutes, and finally analyze the concentration of tetracycline after photocatalysis for the samples taken.

[0057] A blank group was set up during the test: 50 mL of tetracycline solution with a concentration of 20 mg / L, without adding any catalyst material, and was treated under the same test conditions as the group adding the catalyst as a control.

[0058] Figure 4Degradation effect diagrams of BiOCOOH, NiAl-LDH, B / NA-1, B / NA-2, B / NA-3, and B / NA-4 on tetracycline under different photocatalytic treatment time conditions. Figure 4 In which, the ordinate C t / C0, where C0 is the initial concentration of the tetracycline solution; C t is the sampling concentration. It can be seen from the figure that the bismuth formate-nickel aluminum layered double metal hydroxide composite material in the present invention has a good degradation effect on tetracycline, and the degradation effect of B / NA-3 is the best.

[0059] Figure 5 Power curve diagrams of the degradation of tetracycline by BiOCOOH, NiAl-LDH, (B / NA-1, B / NA-2, B / NA-3, B / NA-4). It can be seen from Figure 5 that the degradation rate of B / NA-3 is the highest.

[0060] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a bismuth oxalate-nickel aluminum layered double hydroxide composite material, characterized in that, It includes the following steps: Mix solution I containing a bismuth source and solution II containing nickel-aluminum layered double hydroxide, and then carry out a heating reaction at 120-140 °C to obtain the bismuth oxalate-nickel-aluminum layered double hydroxide composite material.

2. The preparation method according to claim 1, characterized in that, The preparation method of the nickel-aluminum layered double hydroxide includes the following steps: Carry out a hydrothermal reaction on a nickel source and an aluminum source under the action of hexamethylenetetramine.

3. The preparation method according to claim 2, characterized in that, The nickel source is a soluble nickel salt; the aluminum source is a soluble aluminum salt; and / or, the molar ratio of nickel in the nickel source to aluminum in the aluminum source is 0.5-2:1; and / or, the molar ratio of hexamethylenetetramine to nickel in the nickel source is 1-4:

1.

4. The preparation method according to claim 2, characterized in that, The time of the hydrothermal reaction is 6-8 h; and / or, the hydrothermal reaction further includes post-treatments of washing and drying; the drying is carried out at 60-80 °C for 12-18 h.

5. The preparation method according to claim 2, characterized in that, The preparation method of the nickel-aluminum layered double hydroxide includes: dissolving a nickel source and an aluminum source in water, adding hexamethylenetetramine and stirring for 1-2 h, and then carrying out a hydrothermal reaction.

6. The preparation method according to claim 1, characterized in that, The solvent of solution I is N,N-dimethylformamide; and / or, the solvent of solution II is water.

7. The preparation method according to claim 1, characterized in that, The time of the heating reaction is 12-14 h; and / or, the heating reaction further includes post-treatments of washing and drying; the drying is carried out at 60-80 °C for 12-18 h; and / or, the mass ratio of bismuth in the bismuth source to the nickel-aluminum layered double hydroxide is 1.8-4:

1.

8. The bismuth oxalate-nickel-aluminum layered double hydroxide composite material obtained by the preparation method according to any one of claims 1-7.

9. Use of the bismuth oxalate-nickel-aluminum layered double hydroxide composite material according to claim 8 as a photocatalyst.

10. The use according to claim 9, characterized in that, Use in degrading tetracycline as a photocatalyst.

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