Process for the preparation of selenium nanoparticles based on a solvothermal method in aprotic polar solvents

Abstract

The application relates to a preparation method of selenium nanoparticles based on a non-protic polar solvent solvothermal method, and relates to the technical field of selenium nanomaterials, and comprises the following steps: (1) adding selenium powder into a N,N-dimethylformamide solution, carrying out a solvothermal reaction after mixing, naturally cooling after the reaction is completed, and obtaining a selenium precursor solution; (2) dialyzing the selenium precursor solution to obtain an aqueous solution of selenium nanoparticles, and then drying the aqueous solution of the selenium nanoparticles to obtain solid selenium nanoparticles. Compared with a traditional method, the application does not need a reducing agent, has better compatibility, only needs one-step reaction, does not need complex reaction conditions, and has a short reaction time, so the application is more suitable for batch preparation of selenium nanomaterials in enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of selenium nanomaterials, and particularly relates to a preparation method of selenium nanoparticles based on a solvothermal method of an aprotic polar solvent. BACKGROUND

[0002] Selenium is a trace element required by the human body, and an appropriate amount of selenium is beneficial to the human body. To develop a selenium-rich industry, a suitable selenium source is needed to cultivate plants to obtain an organic selenium source beneficial to the human body.

[0003] However, the currently used selenium source is mostly inorganic selenium, i.e., selenate or selenite. These inorganic selenite salts have strong toxicity and are extremely soluble in water, and if applied for a long time, environmental pollution will inevitably occur. In addition to inorganic selenium sources, there are methods such as biological preparation of selenium nanoparticles and ultrasonic preparation of selenium nanoparticles. For example, Bacillus subtilis is cultivated using sodium selenate or sodium selenite, and after about 30 days of cultivation, selenium nanoparticles with a particle size of about 150 nm are obtained. This method uses bacterial cultivation, which not only increases the technical threshold of preparation, but also has a long cultivation period, a large consumption of culture medium, a high price, and is not easy to mass-produce and has a complex preparation process, thereby limiting its application in practice. In the use of ultrasonic method to prepare selenium nanoparticles, an ultrasonic pulverizer is used, and under the action of ultrasonic, niobium dioxide is inserted into selenium molecules to prepare selenium nanoparticles. This method uses expensive niobium dioxide, and the prepared selenium nanoparticles are prone to aggregation and precipitation, so a high-molecular stabilizer needs to be additionally added to prepare selenium nanoparticles, which increases the cost and makes the preparation conditions harsh, and it is also difficult to be widely used. In addition, the most popular method is to use a reducing agent (ascorbic acid, potassium iodide, glutathione or sodium borohydride, etc.) to reduce selenate and selenite, and then add a stabilizer (starch, gum arabic and sodium alginate, etc.) in the solution. The reducing agent reduces selenate and selenite to zero-valent selenium nanoparticles, and then the stabilizer surface reacts with hydrogen bonds or electrostatic effects to prepare selenium nanoparticles. This method needs to use a reducing agent and a stabilizer, which increases the preparation cost, and also needs relatively harsh reaction conditions, which increases the preparation difficulty and makes it difficult to achieve mass production.

[0004] In summary, the existing preparation method of selenium nanomaterials, raw materials are generally selenium dioxide, sodium selenate or sodium selenite, these selenium raw materials are extremely easy to dissolve in water, if used in batches, will flow with the water and be lost, will inevitably cause environmental pollution. The selenium powder itself is not easy to dissolve in water, so the above method does not use selenium powder as raw material to prepare. If the selenium powder is used as raw material, the unreacted selenium powder will precipitate in the solution, which reduces the content of selenate and selenite in the reaction product to a certain extent, and reduces pollution. In view of this, the present application provides a preparation method of selenium nanoparticles based on the solvothermal method of aprotic polar solvent. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a preparation method of selenium nanoparticles based on the solvothermal method of aprotic polar solvent. The purpose is to provide a preparation method of selenium nanoparticles which can be prepared in batches through one-step reaction, has simple reaction, short reaction time and is environmentally friendly.

[0006] In order to solve the above technical problem, the present application provides a preparation method of selenium nanoparticles based on the solvothermal method of aprotic polar solvent, comprising the following steps:

[0007] (1) adding selenium powder into N,N-dimethylformamide solution, mixing and then performing solvothermal reaction, naturally cooling after the reaction is completed, to obtain a selenium precursor solution;

[0008] (2) dialyzing the selenium precursor solution to obtain an aqueous solution of selenium nanoparticles, and then drying the aqueous solution of selenium nanoparticles to obtain solid selenium nanoparticles.

[0009] The principle of the above reaction is that N,N-dimethylformamide (abbreviated as DMF) is a commonly used solvent, and there is no report on the method for preparing selenium nanoparticles by using direct reaction of DMF and selenium powder. DMF is aprotic polar solvent, the positively charged end of the molecule is surrounded by methyl, forming steric hindrance, so that negative ions cannot approach, and only associate with positive ions. The activity of the exposed negative ions is much larger than that of the solvated negative ions. Under high temperature and high pressure, DMF reacts with selenium powder to obtain a selenium reaction precursor solution. When the selenium reaction precursor solution is added dropwise into an aqueous solution, the system of the selenium reaction precursor solution is destroyed, thereby preparing selenium nanoparticles. The technical principle is shown in the following reaction formula:

[0010]

[0011] The particle size of the above-mentioned selenium powder is 80-120 mesh.

[0012] The present application has the following beneficial effects:

[0013] (1) The present application uses non-polar solvent N, N-dimethylformamide and selenium powder to directly prepare selenium nanoparticles under solvothermal conditions at 110-40 DEG C. Compared with the traditional method, the present application does not need reducing agent, has better compatibility, only needs one-step reaction, does not need complex reaction conditions, has short reaction time, and is more suitable for batch preparation of selenium nanoparticle materials in enterprises.

[0014] (2) The preparation process of the present application is very simple, raw materials are easy to obtain, is suitable for large-scale preparation, and has good application prospect in selenium-rich industry.

[0015] (3) The present application directly uses non-polar solvent N, N-dimethylformamide and selenium powder to prepare selenium nanoparticles through solvothermal reaction, unreacted selenium powder is precipitated and separated out in the solution, and the content of selenate and selenite in the reaction product is reduced to a certain extent, thereby reducing pollution.

[0016] On the basis of the above technical solutions, the present application can be further improved as follows.

[0017] Further, the particle size of the selenium nanoparticles is 50-150 nm.

[0018] Further, in step (1), the weight ratio of the selenium powder to N, N-dimethylformamide is (1-20):(10-150).

[0019] Further, in step (1), the weight ratio of the selenium powder to N, N-dimethylformamide is (1-10):(10-100).

[0020] Further, in step (1), the temperature of the solvothermal reaction is 110-220 DEG C, and the time is 4-10 hours.

[0021] Further, in step (1), the temperature of the solvothermal reaction is 130-180 DEG C, and the time is 6-8 hours.

[0022] Further, step (1) comprises the following specific steps: the selenium powder is added to the N, N-dimethylformamide solution, mixed, transferred to a polytetrafluoroethylene lining tube, the polytetrafluoroethylene lining tube is placed in a reaction kettle for assembly, the reaction kettle is placed in a blast oven, the solvothermal reaction is carried out, and the selenium precursor solution is obtained after natural cooling.

[0023] Further, in step (2), the dialysis of the selenium precursor solution is carried out in a dialysis bag, and the molecular weight cut-off of the dialysis bag is 500-3500 Da.

[0024] Further, in step (2), the dialysis of the selenium precursor solution in the dialysis bag is carried out for 18-30 hours.

[0025] Further, step (2) comprises the following specific steps: dialysis of the selenium precursor solution in a dialysis bag, removal of reaction byproducts by replacing water in the dialysis bag every 4-8 hours, obtaining an aqueous solution of selenium nanoparticles in the dialysis bag, and freeze-drying the aqueous solution of selenium nanoparticles to obtain solid selenium nanoparticles.

[0026] Further, the temperature for freeze-drying is -50℃±5, and the time for freeze-drying is determined according to the amount of freezing, i.e. the more the amount, the longer the freeze-drying time. Finally, a freeze-dried powder is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A diagram showing the dissolution of selenium powder in different solvents at room temperature and normal pressure according to the present application;

[0028] Figure 2 A photo of an aqueous solution of selenium nanoparticles prepared in Example 1 of the present application under sunlight;

[0029] Figure 3 An ultraviolet-visible light absorption spectrum of a selenium precursor solution prepared in Example 1 of the present application;

[0030] Figure 4 An infrared spectrum of a selenium precursor solution prepared in Example 1 of the present application;

[0031] Figure 5 A H NMR chart of a selenium precursor solution prepared in Example 1 of the present application; 1

[0032] Figure 6 A particle size distribution chart of selenium nanoparticles prepared in Example 1 of the present application;

[0033] Figure 7 A scanning electron microscope chart of selenium nanoparticles prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0034] The principles and features of the present application are described below, and the examples are only used to explain the present application, and are not intended to limit the scope of the present application.

[0035] Example 1

[0036] This example relates to a method for preparing selenium nanoparticles based on a solvothermal method using aprotic polar solvents, comprising the following steps:

[0037] ​(1) Put 1 part by weight of selenium powder into 10 parts by weight of N,N- dimethylformamide solution, mix and transfer into a polytetrafluoroethylene liner, then put into a stainless steel reaction kettle, tighten and cover, put the reaction kettle into a blast oven, set the temperature to 110-120°C, and react for 4-6 hours. After the reaction is completed, the kettle is naturally cooled, and a selenium powder precursor solution is obtained.

[0038] (2) Put the selenium powder precursor solution prepared in (1) into a dialysis bag for dialysis, the dialysis bag has a molecular weight cut-off of 500-3500 Da, dialysis removes by-products in the reaction process, the dialysis time is 12 hours, and the solution obtained after dialysis is a selenium powder nanoparticle aqueous solution. The aqueous solution is freeze-dried to obtain pink solid selenium powder nanoparticles.

[0039] Example 2

[0040] This example relates to a method for preparing selenium powder nanoparticles based on a non-protic polar solvent solvothermal method, which includes the following steps:

[0041] (1) Put 10 parts by weight of selenium powder into 50 parts by weight of N,N- dimethylformamide solution, mix and transfer into a polytetrafluoroethylene liner, then put into a stainless steel reaction kettle, tighten and cover; put the prepared reaction kettle into a blast oven, set the temperature to 120-150°C, and react for 5-7 hours. After the reaction is completed, the kettle is naturally cooled, and a selenium powder precursor solution is obtained.

[0042] (2) Put the selenium powder precursor solution prepared in (1) into a dialysis bag for dialysis, the dialysis bag has a molecular weight cut-off of 500-3500 Da, dialysis removes by-products in the reaction process, the dialysis time is 25 hours, and the solution obtained after dialysis is a selenium powder nanoparticle aqueous solution. The aqueous solution is freeze-dried to obtain pink solid selenium powder nanoparticles.

[0043] Example 3

[0044] This example relates to a method for preparing selenium powder nanoparticles based on a non-protic polar solvent solvothermal method, which includes the following steps:

[0045] (1) Put 20 parts by weight of selenium powder into 100 parts by weight of N,N- dimethylformamide solution, mix and transfer into a polytetrafluoroethylene liner, then put into a stainless steel reaction kettle, tighten and cover; put the prepared reaction kettle into a blast oven, set the temperature to 130-180°C, and react for 6-8 hours. After the reaction is completed, the kettle is naturally cooled, and a selenium powder precursor solution is obtained.

[0046] (2) The prepared selenium powder precursor solution in (1) is placed in a dialysis bag for dialysis, the dialysis bag has a molecular weight cut-off of 500-3500 Da, the dialysis removes by-products of the reaction process, the dialysis time is 30 hours, and the solution obtained after the dialysis is completed is a selenium powder nanoparticle aqueous solution. The aqueous solution is then freeze-dried to obtain pink solid selenium powder nanoparticles.

[0047] Example 4

[0048] This example relates to a method for preparing selenium powder nanoparticles based on a non-protic polar solvent solvothermal method, comprising the following steps:

[0049] (1) 10 parts by weight of selenium powder is added to 100 parts by weight of an N,N-dimethylformamide solution, mixed and transferred to a polytetrafluoroethylene liner, and then placed in a stainless steel reaction kettle body, which is tightly closed and covered. The prepared reaction kettle is placed in a forced air oven, the temperature is set to 150-190°C, and the reaction is carried out for 5-8 hours. After the reaction is completed, the kettle body is naturally cooled, and a selenium powder precursor solution is obtained.

[0050] (2) The prepared selenium powder precursor solution in (1) is placed in a dialysis bag for dialysis, the dialysis bag has a molecular weight cut-off of 500-3500 Da, the dialysis removes by-products of the reaction process, the dialysis time is 18 hours, and the solution obtained after the dialysis is completed is a selenium powder nanoparticle aqueous solution. The aqueous solution is then freeze-dried to obtain pink solid selenium powder nanoparticles.

[0051] Example 5

[0052] This example relates to a method for preparing selenium powder nanoparticles based on a non-protic polar solvent solvothermal method, comprising the following steps:

[0053] (1) 10 parts by weight of selenium powder is added to 150 parts by weight of an N,N-dimethylformamide solution, mixed and transferred to a polytetrafluoroethylene liner, and then placed in a stainless steel reaction kettle body, which is tightly closed and covered. The prepared reaction kettle is placed in a forced air oven, the temperature is set to 180-220°C, and the reaction is carried out for 8-10 hours. After the reaction is completed, the kettle body is naturally cooled, and a selenium powder precursor solution is obtained.

[0054] (2) The prepared selenium powder precursor solution in (1) is placed in a dialysis bag for dialysis, the dialysis bag has a molecular weight cut-off of 500-3500 Da, the dialysis removes by-products of the reaction process, the dialysis time is 24 hours, and the solution obtained after the dialysis is completed is a selenium powder nanoparticle aqueous solution. The aqueous solution is then freeze-dried to obtain pink solid selenium powder nanoparticles.

[0055] Comparative Example

[0056] The N,N-dimethylformamide solution in Example 1 was replaced with any one of water, ethanol, acetone, chloroform, toluene, or diethyl ether, while all other aspects remained the same as in Example 1.

[0057] At room temperature and pressure, selenium powder is insoluble in various common reagents, such as water, ethanol, acetone, chloroform, toluene, diethyl ether, dimethyl sulfoxide, and N,N-dimethylformamide (e.g., ...). Figure 1 ).

[0058] Under solvothermal conditions of 110-240℃, selenium reacts only in N,N-dimethylformamide to form a black selenium precursor solution. After purification, red selenium nanoparticles (such as...) are obtained. Figure 2 In other solvents (control examples), the generated selenium forms selenium nanotubes, nanoribbons, or nanosheets, all of which are unstable in aqueous solutions and precipitate. This indicates that this solvothermal method primarily prepares selenium-composite metallic materials.

[0059] The selenium powder precursor solution prepared in Example 1 was subjected to ultraviolet-visible absorption, infrared and nuclear magnetic resonance detection (e.g., Figures 3-5 Absorption by ultraviolet-visible light (e.g.) Figure 3 As can be seen, the strongest peak is observed at a wavelength of 293 nm, which corresponds to the non-bonding electronic n→π* transition, indicating hydrogen bonding or electrostatic interaction between nitrogen and selenium on the surface amino group. Infrared spectroscopy (such as...) shows... Figure 4 The wave number in the sample is 3400 cm⁻¹. -1 The characteristic bimodal intensity of the amino groups is basically consistent, and a blue shift may occur, indicating that the nitrogen on the surface amino groups forms hydrogen bonds or electrostatic interactions with selenium, thereby forming a stable selenium precursor solution. This also proves that its surface contains amino functional groups. 1 H NMR spectrum (e.g.) Figure 5 It can be seen that N,N-dimethylformamide is located at δ a =2.921ppm and δ b A distinct resonance peak is observed at 2.851 ppm, while the resonance peak of the selenium precursor solution after the reaction is significantly shifted towards H. a = 2.887ppm(q,CH2) and H b = 2.982 ppm (t, CH2) shift, these changes may be due to the chelation between nitrogen and selenium in N,N-dimethylformamide.

[0060] The particle size of the selenium nanoparticles prepared in Example 1 was analyzed using a particle size analyzer. Figure 6 The average particle size was found to be around 100 nm. When the morphology of the selenium nanoparticles prepared in Example 1 was observed using a scanning electron microscope (SEM), it was found that... Figure 7 The results showed that the selenium nanoparticles were spherical with a particle size of about 100 nm, consistent with the particle size analysis results.

[0061] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0062] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for the preparation of selenium nanoparticles based on a solvothermal process in a non-protic polar solvent, characterized in that, The method comprises the following steps: (1) adding selenium powder into N,N-dimethylformamide solution, mixing and then performing solvothermal reaction, naturally cooling after the reaction, and obtaining selenium precursor solution; (2) dialyzing the selenium precursor solution to obtain aqueous solution of selenium nanoparticles, and then drying the aqueous solution of selenium nanoparticles to obtain solid selenium nanoparticles; The particle size of the selenium nanoparticles is 50-150 nm; In step (2), the dialysis of the selenium precursor solution is performed in a dialysis bag, and the molecular weight cut-off of the dialysis bag is 500-3500 Da; Step (2) comprises the following specific steps: dialyzing the selenium precursor solution in a dialysis bag, replacing water every 4-8 hours during the dialysis to remove reaction byproducts, obtaining aqueous solution of selenium nanoparticles in the dialysis bag, and then freeze-drying the aqueous solution of selenium nanoparticles to obtain solid selenium nanoparticles; In step (1), the temperature of the solvothermal reaction is 110-220 ℃, and the time is 4-10 hours.

2. The method for preparing selenium nanoparticles based on a non-protic polar solvent solvothermal method according to claim 1, characterized in that, In step (1), the weight ratio of the selenium powder to N,N-dimethylformamide is (1-20):(10-150).

3. The method for preparing selenium nanoparticles based on a non-protic polar solvent solvothermal method according to claim 1, characterized in that, In step (1), the weight ratio of the selenium powder to N,N-dimethylformamide is (1-10):(10-100).

4. The method for preparing selenium nanoparticles based on a non-protic polar solvent solvothermal method according to claim 1, characterized in that, In step (1), the temperature of the solvothermal reaction is 130-180 ℃, and the time is 6-8 hours.

5. The method for preparing selenium nanoparticles based on a non-protic polar solvent solvothermal process according to any one of claims 1 to 4, characterized in that, The step (1) comprises the following specific steps: adding selenium powder into N,N-dimethylformamide solution, mixing and then transferring into a polytetrafluoroethylene lining tube, placing the polytetrafluoroethylene lining tube into a reaction kettle for assembly, placing the reaction kettle into a blast oven for solvothermal reaction, naturally cooling after the reaction, and obtaining selenium precursor solution.

6. The method for preparing selenium nanoparticles based on a non-protic polar solvent solvothermal method according to claim 1, characterized in that, In step (2), the dialysis of the selenium precursor solution in the dialysis bag is performed for 18-30 hours.

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