A kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material, its preparation method and application

Abstract

This invention belongs to the field of nanomaterials and discloses a method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material, comprising the following steps: dissolving nickel nitrate, iron nitrate, urea, and trisodium citrate to obtain a precursor reaction solution, heating the solution to react, grinding and mixing the obtained nano-sized nickel-iron dihydroxyoxide with kaolinite, and calcining the mixture to obtain the final product. The kaolinite / nickel-iron dihydroxyoxide heterostructure prepared by this method forms stable interfacial chemical bonds at the interface between kaolinite and nickel-iron dihydroxyoxide, which can effectively enhance the photocatalytic performance of natural kaolinite; it can be used for the catalytic degradation of Rhodamine B with excellent degradation effect; and the preparation process is simple and easy to scale up.

Description

Technical Field

[0001] This invention belongs to the technical field of nanomaterial preparation, specifically relating to a method for preparing and applying a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material. Background Technology

[0002] Natural kaolinite is a widely distributed layered aluminosilicate mineral found in the Earth's surface environment. As one of the most important clay minerals, natural kaolinite is widely used in traditional ceramics, refractories, cement, and petrochemicals. Due to its abundant reserves, environmental friendliness, and good stability, natural kaolinite is widely used as a photocatalyst carrier. Due to isomorphic substitution in the Earth's crust, the passage of natural iron / titanium ions replaces a small number of aluminum and silicon atoms in the kaolinite lattice, resulting in significant photochemical activity in natural kaolinite. However, due to limitations in aluminosilicate composition and iron / titanium ion doping content, the photochemical activity of natural kaolinite is not outstanding, greatly restricting its direct application as a photocatalyst. Therefore, improving the photochemical activity of natural kaolinite is of great significance.

[0003] Calcination, acid leaching, and material composites are common methods to improve the photochemical activity of natural kaolinite. However, calcination and acid leaching often directly damage the structure of natural kaolinite, limiting its further applications. Composites with other functional materials to construct heterostructures are an effective means to improve the photochemical activity of natural kaolinite. For most kaolinite-based composite photocatalytic materials, kaolinite is usually used only as a common support to assist in improving the photocatalytic performance of semiconductor photocatalysts. In the natural kaolinite lattice, only the local structures replaced by iron / titanium ions exhibit significant photochemical activity. Due to this unique photochemical activity of natural kaolinite, constructing ordinary semiconductor heterojunctions has limited effect on improving its photochemical activity, hence related research is scarce. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for preparing kaolinite / nickel-iron dihydroxy oxide composite material, which is obtained by simple physical grinding of nickel-iron dihydroxy oxide and kaolinite powder, followed by calcination.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] A method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material includes the following steps:

[0007] (1) Dissolve nickel nitrate, ferric nitrate, urea and trisodium citrate in water to obtain a precursor reaction solution;

[0008] (2) The precursor reaction solution is heated to prepare nano-sized nickel-iron dihydroxy oxide;

[0009] (3) Grind and mix the nano-sized nickel-iron dihydroxy oxide with kaolinite to obtain a mixture;

[0010] (4) The mixture is calcined to obtain the kaolinite / nickel-iron double hydroxyl oxide composite photocatalytic material.

[0011] This invention utilizes the abundant surface hydroxyl groups of kaolinite and nano-sized nickel-iron dihydroxy oxides to form stable interfacial chemical bonds at the heterojunction interface during calcination and dehydration. These interfacial chemical bonds not only allow for tighter bonding at the heterostructure interface but also effectively promote the transport and separation of photogenerated carriers, thereby significantly improving the photocatalytic performance of natural kaolinite.

[0012] In the above preparation method, preferably, in step (1), the nickel nitrate is nickel nitrate hexahydrate and the ferric nitrate is ferric nitrate nonahydrate.

[0013] Preferably, in step (1), the mass ratio of nickel nitrate to ferric nitrate is 1 to 3:1, the mass ratio of ferric nitrate to trisodium citrate is 20 to 30:1, and the mass ratio of urea to nitrate in the precursor reaction solution is 2 to 8:1.

[0014] Preferably, in step (2), the temperature of the heating reaction is 120-160°C and the reaction time is 24-48h.

[0015] Preferably, in step (3), the mass ratio of the nano-sized nickel-iron dihydroxy oxide to kaolinite is 1:1.5-15.

[0016] Preferably, in step (4), the calcination temperature is 200-600°C, the calcination time is 1-24 hours, and the furnace is placed in a muffle furnace for calcination.

[0017] Based on a general inventive concept, the present invention also provides a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material prepared by the above-described preparation method.

[0018] Preferably, the kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material is a dispersed nanosheet with a size reaching the micrometer level.

[0019] Based on a general inventive concept, the present invention also provides an application of kaolinite / nickel-iron dihydroxyoxide composite photocatalyst in the photocatalytic degradation of Rhodamine B.

[0020] In the above-mentioned application, preferably, the method for photocatalytic degradation of Rhodamine B is as follows: the kaolinite / nickel-iron dihydroxyoxide composite photocatalyst material degrades Rhodamine B under potassium persulfate conditions.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The preparation method provided by the present invention yields a kaolinite / nickel-iron dihydroxy oxide heterostructure, in which stable interfacial chemical bonds are formed at the interface between kaolinite and nickel-iron dihydroxy oxide, which can effectively improve the photocatalytic performance of natural kaolinite.

[0023] 2. The preparation method of the kaolinite / nickel-iron dihydroxy oxide composite material provided by the present invention is simple and easy to scale up for production.

[0024] 3. The kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material of the present invention can be used for the catalytic degradation of Rhodamine B, with excellent degradation effect. Attached Figure Description

[0025] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Transmission electron microscopy image of the kaolinite / nickel-iron dihydroxyoxide composite photocatalyst material prepared in Example 1;

[0027] Figure 2 The degradation curve of kaolinite / nickel-iron dihydroxyoxide composite material in potassium persulfate is shown.

[0028] Figure 3 Al 2p X-ray photoelectron spectroscopy (XPS) of kaolinite / nickel-iron dihydroxyoxide composite material;

[0029] Figure 4 The Si 2p X-ray photoelectron spectrum (XPS) of the kaolinite / nickel-iron dihydroxyoxide composite material;

[0030] Figure 5 O1s X-ray photoelectron spectroscopy (XPS) of kaolinite / nickel-iron dihydroxyoxide composite material;

[0031] Figure 6 The image shows the Fe 2p X-ray photoelectron spectrum (XPS) of the kaolinite / nickel-iron dihydroxyoxide composite material.

[0032] Figure 7 The image shows the Ni 2p X-ray photoelectron spectrum (XPS) of the kaolinite / nickel-iron dihydroxyoxide composite material. Detailed Implementation

[0033] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0036] In the following text, C(Ni) 2+ C(Fe) is the concentration of nickel nitrate hexahydrate in the precursor reaction solution. 3+ C(trisodium citrate) is the concentration of ferric nitrate nonahydrate in the precursor reaction solution, C(urea) is the concentration of urea in the precursor reaction solution, and C(NO3) is the concentration of urea in the precursor reaction solution. -1 () represents the concentration of nitrate ions in the precursor reaction solution.

[0037] Example 1:

[0038] A method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material includes the following steps:

[0039] (1) Dissolve nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea and trisodium citrate in deionized water to obtain a precursor reaction solution; the mass concentration ratios in the precursor reaction solution are as follows: the mass ratio of nickel nitrate hexahydrate to ferric nitrate nonahydrate is 2.15:1, the mass ratio of ferrous nitrate nonahydrate to trisodium citrate is 26.5:1, and the mass ratio of urea to nitrate in the solution is 4.8:1;

[0040] (2) The precursor reaction solution was reacted at 120°C for 24-48 h to obtain nano-sized nickel-iron dihydroxy oxide;

[0041] (3) Mix and grind 0.93g of kaolinite and 0.0718g of nickel-iron dihydroxy oxide for 15min, then calcine in a muffle furnace at 300℃ for 2h, and cool to room temperature to obtain the kaolinite / nickel-iron dihydroxy oxide composite material prepared in this embodiment.

[0042] like Figure 1Transmission electron microscopy analysis revealed that the kaolinite / nickel-iron dihydroxy oxide composite material consists of dispersed nanosheets with nanoscale dimensions, and the nickel-iron dihydroxy oxide has a size of approximately 40 nanometers.

[0043] The photocatalytic performance of the kaolinite / nickel-iron dihydroxyoxide composite material prepared in this embodiment was characterized by the degradation of Rhodamine B using potassium persulfate. The photocatalytic degradation conditions were: 10 mg of kaolinite / nickel-iron dihydroxyoxide composite material, 2 mL of potassium persulfate, and 50 mL of 0.02 mM Rhodamine B. The degradation curves of Rhodamine B are shown below. Figure 2 As shown.

[0044] Depend on Figure 2 It was found that in the presence of potassium persulfate alone, Rhodamine B underwent less than 10% photodegradation within 45 minutes. With kaolinite (Kaol) and nickel-iron dihydroxyl oxide (NF) as photocatalysts, the photodegradation of Rhodamine B reached 90% and 40%, respectively. The kaolinite / nickel-iron dihydroxyl oxide composite (NFK) almost completely degraded Rhodamine B within 30 minutes, indicating a significant improvement in the photocatalytic performance of the composite material. Furthermore, the photocatalytic performance of the physically mixed kaolinite and nickel-iron dihydroxyl oxide mixture (NF / Kaol) was significantly worse than that of NFK, indicating that the interfacial chemical bonds formed by the kaolinite / nickel-iron dihydroxyl oxide significantly improved the photocatalytic performance.

[0045] Depend on Figure 3-7 It can be seen that, compared with the XPS diagrams of kaolinite (Kaol) and nickel-iron dihydroxyoxide (NF) calcined at 300℃, the Al 2p, Si 2p, and O 1s peaks of the kaolinite / nickel-iron dihydroxyoxide composite (NFK) shifted to lower binding energies by 0.12 eV, 0.1 eV, and 0.1 eV, respectively, while the Fe 2p and Ni 2p peaks shifted to higher binding energies by 0.69 eV and 1.2 eV, respectively. This is because the hydroxyl groups on the NF surface transfer to the kaolinite surface during the 300℃ calcination process, thereby forming Ni(Fe)-O-Al(Si) interfacial chemical bonds. However, in the composite material (NF / Kaol) of kaolinite (Kaol) and nickel-iron dihydroxyoxide (NF) physically mixed after 300℃ calcination, the Al 2p, Si 2p, O 1s, Fe 2p, and Ni 2p peaks all shifted to higher binding energies, indicating that purely physical mixing cannot form interfacial chemical bonds.

[0046] Example 2:

[0047] A method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material includes the following steps:

[0048] (1) Dissolve nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea and trisodium citrate in deionized water to obtain a precursor reaction solution; the mass concentration ratios in the precursor reaction solution are as follows: the mass ratio of nickel nitrate hexahydrate to ferric nitrate nonahydrate is 2.15:1, the mass ratio of ferric nitrate nonahydrate to trisodium citrate is 26.5:1, and the mass ratio of urea to nitrate in the solution is 4.8:1;

[0049] (2) The precursor reaction solution was reacted at 120°C for 24-48 h to obtain nano-sized nickel-iron dihydroxy oxide;

[0050] (3) Mix and grind 0.2872g of kaolinite and 0.0718g of nickel-iron dihydroxy oxide for 15min, put them into a muffle furnace and react at 400℃ for 2h, and cool to room temperature to obtain the kaolinite / nickel-iron dihydroxy oxide composite material prepared in this embodiment.

[0051] Example 3:

[0052] A method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material includes the following steps:

[0053] (1) Nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea and trisodium citrate were dissolved in deionized water to obtain a precursor reaction solution. The mass concentration ratios in the precursor reaction solution were as follows: the mass ratio of nickel nitrate hexahydrate to ferrous nitrate nonahydrate was 2.15:1, the mass ratio of ferrous nitrate nonahydrate to trisodium citrate was 26.5:1, and the mass ratio of urea to nitrate in the solution was 4.8:1.

[0054] (2) The precursor reaction solution was reacted at 120-160℃ for 24-48h to obtain nano-sized nickel-iron dihydroxy oxide.

[0055] (3) Mix and grind 0.1077g of kaolinite and 0.0718g of nickel-iron dihydroxy oxide for 15min, put them into a muffle furnace and react at 500℃ for 2h, and cool to room temperature to obtain the kaolinite / nickel-iron dihydroxy oxide composite material prepared in this embodiment.

Claims

1. A method for preparing a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material, characterized in that, Includes the following steps: (1) Dissolve nickel nitrate, ferric nitrate, urea and trisodium citrate in water to obtain a precursor reaction solution; the mass ratio of nickel nitrate to ferric nitrate is 1~3:1, the mass ratio of ferric nitrate to trisodium citrate is 20~30:1, and the mass ratio of urea to nitrate in the precursor reaction solution is 2~8:

1. (2) The precursor reaction solution is heated at 120-160℃ for 24-48h to obtain nano-sized nickel-iron dihydroxy oxide; (3) Grind and mix the nano-sized nickel-iron dihydroxy oxide and kaolinite at a mass ratio of 1:1.5-15 to obtain a mixture; (4) The mixture is calcined at 300 °C for 1 to 24 h to obtain the kaolinite / nickel-iron double hydroxyl oxide composite photocatalytic material.

2. The preparation method according to claim 1, characterized in that, In step (4), it is placed in a muffle furnace for calcination.

3. A kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material prepared by the preparation method according to any one of claims 1-2, characterized in that, The kaolinite / nickel-iron dihydroxyoxide composite photocatalyst material is a dispersed nanosheet with a size reaching the micrometer level.

4. The application of a kaolinite / nickel-iron dihydroxyoxide composite photocatalytic material prepared by the preparation method according to any one of claims 1-2 in the photocatalytic degradation of Rhodamine B, characterized in that, The method for photocatalytic degradation of Rhodamine B is as follows: the kaolinite / nickel-iron dihydroxyoxide composite photocatalyst material degrades Rhodamine B under potassium persulfate conditions.

Images