阅读说明：本技术 一种基于熔融盐法制备二氧化钍纳米材料的方法以及由此得到的二氧化钍纳米材料 (Method for preparing thorium dioxide nano material based on molten salt method and thorium dioxide nano material obtained by method ) 是由 张强 乔延波 钱正华 刘学阳 李霖 段熙雷 于 2021-11-03 设计创作，主要内容包括：本发明涉及一种基于熔融盐法制备二氧化钍纳米材料的方法,其包括：由氯化锂和氯化钾组成熔盐,六水硝酸钍与熔盐的摩尔比为1：5～1：80,组成原料；将所述原料搅拌混合均匀,得到混合料；将所述混合料升温至400℃～800℃,煅烧1～8小时,完全冷却后得到反应产物；在所述反应产物中加入水后超声,得到乳白色悬浮液；将所述乳白色悬浮液用抽滤装置进行抽滤,接着用纯水反复抽滤洗涤以除去未反应的原料,然后烘干,得到二氧化钍纳米材料。根据本发明的另一个方面提供一种通过上述的方法制备得到的二氧化钍纳米材料。根据本发明的方法,可以实现单分散纳米级的二氧化钍的制备,价格便宜,清洁且可扩展并且易于规模化。(The invention relates to a method for preparing thorium dioxide nano material based on a molten salt method, which comprises the following steps: the molten salt is composed of lithium chloride and potassium chloride, and the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 5-1: 80, forming raw materials; uniformly stirring and mixing the raw materials to obtain a mixture; heating the mixture to 400-800 ℃, calcining for 1-8 hours, and completely cooling to obtain a reaction product; adding water into the reaction product, and performing ultrasonic treatment to obtain milky suspension; and carrying out suction filtration on the milky suspension by using a suction filtration device, then repeatedly carrying out suction filtration and washing by using pure water to remove unreacted raw materials, and then drying to obtain the thorium dioxide nano material. According to another aspect of the invention, the thorium dioxide nano-material prepared by the method is provided. According to the method, the preparation of the monodisperse nano-scale thorium dioxide can be realized, and the method is low in price, clean, extensible and easy to scale.)

1. A method for preparing thorium dioxide nano material based on a molten salt method is characterized by comprising the following steps:

s1, forming molten salt by lithium chloride and potassium chloride, wherein the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 5-1: 80, forming raw materials;

s2, uniformly stirring and mixing the raw materials to obtain a mixture;

s3, heating the mixture to 400-800 ℃, calcining for 1-8 hours, and completely cooling to obtain a reaction product;

s4, adding water into the reaction product, and performing ultrasonic treatment to obtain milky suspension;

and S5, performing suction filtration on the milky white suspension by using a suction filtration device, repeatedly performing suction filtration and washing by using pure water to remove unreacted raw materials, and drying to obtain the thorium dioxide nano material.

2. The method according to claim 1, characterized in that in step S1, the molten salt is composed of 59 mol% lithium chloride and 41 mol% potassium chloride.

3. The method of claim 1, wherein in step S2, the raw material is placed in an alumina crucible and stirred to mix homogeneously.

4. The method of claim 1, wherein in step S3, the mix is placed in a box-type resistance furnace and heated.

5. The method of claim 1, wherein in step S3, the temperature is increased at a rate of 5-15 ℃/min.

6. The method of claim 1, wherein in step S4, the reaction product is transferred to a beaker, and sufficient water is added to the beaker for ultrasonic dissolution to obtain a milky white suspension.

7. The method of claim 1, wherein in step S5, suction filtration washing is repeated to remove unreacted lithium chloride and potassium chloride.

8. The method of claim 1, wherein the drying is performed at 100 ℃ in step S5.

9. Thorium dioxide nanomaterial prepared by the method according to any one of claims 1 to 8.

10. Thorium dioxide nanomaterial according to claim 9, characterized in that the mean particle size of the thorium dioxide nanomaterial is between 50nm and 150 nm.

Technical Field

The invention relates to the technical field of materials, in particular to a method for preparing a thorium dioxide nano material based on a molten salt method and the thorium dioxide nano material obtained by the method.

Background

Nanomaterials are not only very important markers in the field of miniaturization, but also important milestones, since the nanoscale lies between the atomic and quantum domains and the overall scale. Once materials fall to the nanometer scale, their physical, biological and chemical properties are controlled primarily by quantum physics, rather than classical physics determining the bulk phase. The main reasons for this difference are the increased surface area, the improved chemical reactivity and the improved mechanical strength. Nanomaterials have attracted much attention in the scientific community, especially for applications in the optical, magnetic and catalytic fields.

Nano thorium dioxide material (ThO)₂) The catalyst is mainly used for nuclear fuel, and can also be used as a catalyst, an electrode material or a high-temperature resistant material and the like. At present, the preparation method of the nano thorium dioxide comprises the following steps: precipitation, hydrothermal synthesis, photochemical reaction, and combustion synthesis. These processes are not suitable for scale-up due to high cost, difficulty in scale-up, product carry-over and large amounts of liquid waste. The most common preparation method of thorium dioxide is to burn thorium nitrate solution after reacting with oxalic acid, and grinding the thorium nitrate solution after burning to achieve high density, so the steps are complicated and radioactive dust can be generated. The aqueous phase wet chemical-based process usually needs two steps of precipitation and calcination to obtain the nano thorium dioxide material, and the size control of the powder is very difficult.

Disclosure of Invention

In order to solve the problems of complex process, uneven particles and the like existing in the preparation method of the nanometer thorium dioxide material in the prior art, the invention provides a method for preparing the thorium dioxide nanometer material based on a molten salt method and the thorium dioxide nanometer material obtained by the method.

According to one aspect of the invention, a method for preparing thorium dioxide nano material based on a molten salt method is provided, which comprises the following steps: s1, forming molten salt by lithium chloride and potassium chloride, wherein the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 5-1: 80, forming raw materials; s2, uniformly stirring and mixing the raw materials to obtain a mixture; s3, heating the mixture to 400-800 ℃, calcining for 1-8 hours, and completely cooling to obtain a reaction product; s4, adding water into the reaction product, and performing ultrasonic treatment to obtain milky suspension; and S5, performing suction filtration on the milky white suspension by using a suction filtration device, repeatedly performing suction filtration and washing by using pure water to remove unreacted raw materials, and drying to obtain the thorium dioxide nano material.

According to the method, thorium nitrate hexahydrate is used as a thorium source, lithium chloride and potassium chloride are used as molten salts, the temperature is kept for 1-8 hours in a resistance furnace at 400-800 ℃, reaction products are obtained, then the reaction products are washed with distilled water and dried, the thorium dioxide nano material is prepared based on a molten salt method, and the complex processes of firing and grinding of a conventional preparation method can be omitted.

Preferably, in step S1, the molten salt is composed of 59 mol% of lithium chloride and 41 mol% of potassium chloride.

Preferably, in step S2, the raw materials are placed in an alumina crucible and stirred to mix uniformly.

Preferably, in step S3, the mix is placed in a box-type resistance furnace and heated.

Preferably, in step S3, the temperature is increased at a rate of 5-15 deg.C/min. In a preferred embodiment, the temperature is increased at a rate of 10 deg.C/min.

Preferably, in step S3, the temperature is raised to 400-600 ℃ for calcination. More preferably, in step S3, the temperature is raised to 400 to 500 ℃ for calcination. More preferably, in step S3, the temperature is raised to 400 to 450 ℃ for calcination.

Preferably, in step S3, the calcination time is 1-6 h. More preferably, in step S3, the calcination time is 1-4 h. More preferably, in step S3, the calcination time is 1-2 h.

Preferably, in step S4, the reaction product is transferred to a beaker, and sufficient water is added to the beaker for ultrasonic dissolution to give a milky white suspension.

Preferably, in step S5, suction filtration washing is repeated to remove unreacted lithium chloride and potassium chloride.

Preferably, in step S5, drying is performed at 100 ℃.

According to another aspect of the invention, the thorium dioxide nano-material prepared by the method is provided.

Preferably, the thorium dioxide nano-material has an average particle size of 50nm-150 nm. In a preferred embodiment, the thorium dioxide nanomaterial has an average particle size of 100 nm.

The preparation of monodisperse nanoscale thorium dioxide nanomaterials by the method according to the invention based on the molten salt Method (MSS) allows the preparation of thorium dioxide nanoparticles, which is promising for the synthesis of thorium dioxide nanomaterials on an industrial level, because the molten salt has various advantageous properties, such as non-toxicity, cost-efficiency, low vapor pressure, easy availability, high thermal capacity, large electrochemical range and high ionic conductivity, cheap price, clean and scalable and easy to scale. Moreover, the raw materials used in the method are all easy to dissolve in water, and the reaction products can be cleaned by water, so that the thorium dioxide nano material prepared by the molten salt method is high in purity; according to the method, the thorium dioxide nano material is prepared based on a molten salt method, a liquid phase environment is generated at 400-800 ℃, the mobility and the contact area of reactants in the molten salt are enhanced, and effective ion diffusion and chemical reaction among the reactants are promoted, so that the product forming temperature is reduced, uniform nano particles are obtained, and the morphology is uniform. In a word, the method has the characteristics of short period (which is different from dozens of hours to several days compared with the common hydrothermal method) and simple process, and the prepared thorium dioxide nano material has high purity and uniform particles.

Drawings

FIG. 1 is an XRD pattern of thorium dioxide nanomaterial prepared according to example 15 of the present invention;

FIG. 2 is an SEM image of thorium dioxide nanomaterial prepared according to example 15 of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The purity of the thorium nitrate hexahydrate in the following examples is more than or equal to 95 weight percent, and the particle size is less than or equal to 2 mm.

The purity of lithium chloride in the following examples is more than or equal to 97 wt%, and the particle size is less than or equal to 0.8 mm.

The purity of potassium chloride in the following examples is more than or equal to 99.8 wt%, and the particle size is less than or equal to 0.1 mm.

Example 1

Taking 59 mol% of lithium chloride and 41 mol% of potassium chloride as molten salt, wherein the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 5, forming raw material ingredients.

And step two, placing the raw materials in an alumina crucible, and stirring and mixing uniformly to obtain a mixture.

And step three, putting the mixture into a box-type resistance furnace, heating to 500 ℃ at the speed of 10 ℃/min, calcining for 4 hours, and obtaining a reaction product after the sample is completely cooled.

And step four, transferring the reaction product from the crucible to a beaker, and adding sufficient water into the beaker for ultrasonic dissolution to obtain a milky white suspension.

And fifthly, carrying out suction filtration on the milky white suspension by using a suction filtration device, repeatedly carrying out suction filtration and washing for eight times by using pure water, and drying at 100 ℃ to obtain the thorium dioxide nano material prepared based on the molten salt method.

Example 2

In this example, except that the mole ratio of the thorium nitrate hexahydrate to the molten salt is 1: 10 as in example 1.

Example 3

In this example, except that the mole ratio of the thorium nitrate hexahydrate to the molten salt is 1: 20 as in example 1.

Example 4

In this example, except that the mole ratio of the thorium nitrate hexahydrate to the molten salt is 1: 40 as in example 1.

Example 5

In this example, except that the mole ratio of the thorium nitrate hexahydrate to the molten salt is 1: 80 as in example 1.

Example 6

Taking 59 mol% of lithium chloride and 41 mol% of potassium chloride as molten salt, wherein the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 20, forming raw material ingredients.

And step two, placing the raw materials in an alumina crucible, and stirring and mixing uniformly to obtain a mixture.

And step three, putting the mixture into a box-type resistance furnace, heating to 500 ℃ at the speed of 10 ℃/min, calcining for 1 hour, and obtaining a reaction product after the sample is completely cooled.

And step four, transferring the reaction product from the crucible to a beaker, and adding sufficient water into the beaker for ultrasonic dissolution to obtain a milky white suspension.

And fifthly, carrying out suction filtration on the milky white suspension by using a suction filtration device, repeatedly carrying out suction filtration and washing for eight times by using pure water, and drying at 100 ℃ to obtain the thorium dioxide nano material prepared based on the molten salt method.

Example 7

This example is the same as example 6 except that the calcination time was 3 hours.

Example 8

This example is the same as example 6 except that the calcination time was 5 hours.

Example 9

This example is the same as example 6 except that the calcination time was 6 hours.

Example 10

This example is the same as example 6 except that the calcination time was 8 hours.

Example 11

Taking 59 mol% of lithium chloride and 41 mol% of potassium chloride as molten salt, wherein the molar ratio of thorium nitrate hexahydrate to the molten salt is 1: 20, forming raw material ingredients.

And step two, placing the raw materials in an alumina crucible, and stirring and mixing uniformly to obtain a mixture.

And step three, putting the mixture into a box-type resistance furnace, heating to 400 ℃ at the speed of 10 ℃/min, calcining for 1 hour, and obtaining a reaction product after the sample is completely cooled.

And step four, transferring the reaction product from the crucible to a beaker, and adding sufficient water into the beaker for ultrasonic dissolution to obtain a milky white suspension.

And fifthly, carrying out suction filtration on the milky white suspension by using a suction filtration device, repeatedly carrying out suction filtration and washing for eight times by using pure water, and drying at 100 ℃ to obtain the thorium dioxide nano material prepared based on the molten salt method.

Example 12

This example is the same as example 11 except that the temperature of the box-type resistance furnace was raised to 450 ℃.

Example 13

This example is the same as example 11 except that the temperature of the box-type resistance furnace was raised to 600 ℃.

Example 14

This example is the same as example 11 except that the temperature of the box-type resistance furnace was raised to 700 ℃.

Example 15

This example is the same as example 11 except that the temperature of the box-type resistance furnace was raised to 800 ℃. FIG. 1 is the XRD pattern of the thorium dioxide nano-material prepared in the embodiment, and the standard substance ThO₂The positions of peaks of the spectra are matched, and diffraction peaks of other substances do not appear, so that the sample is single ThO₂The phase purity is high. FIG. 2 is an SEM image of thorium dioxide nanomaterial prepared in the embodiment, in which ThO is present₂The particle size and the dispersion degree are uniform, and the average particle size is about 100 nm.

The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.