CN102151528A - High purity nano material and preparation method thereof - Google Patents

Abstract

The invention discloses a high-purity nanometer material and a preparation method thereof, which is characterized in that it comprises the following steps: (1) pretreating cation exchange fibers or ion exchange resins with acid and alkali, and washing them with deionized water to make the conductivity less than 100μS /cm; (2) Add a certain concentration of precursor salt ion solution into the fiber/resin solution, and gently stir for pre-exchange of ions to transform the fiber/resin; (3) Add a certain concentration of urea solution into the transformed fiber/resin In the system, after uniform stirring, hydrothermal treatment is carried out under certain temperature and time conditions; (4) the product is ultrasonically separated from fibers, filtered, centrifuged, dried, and then roasted. The low-temperature dual-control synthesis of nanomaterials with different shapes is realized; the impurity ions in the system are enriched on the fiber/resin through the exchange reaction, and there is no need to wash the product. The whole synthesis process is energy-saving and environmentally friendly, which opens up a new way for the synthesis of high-purity nanomaterials.

Description

A kind of high-purity nano material and preparation method thereof

technical field

The invention relates to a high-purity nanometer material and a preparation method thereof.

Background technique

Nanomaterials have special properties. The high dispersion of nanomaterials and a large number of interfaces provide short-range diffusion paths for atoms, resulting in high diffusivity, which has a significant impact on creep and superplasticity, and enhances the solid solubility of limited solid solutions. The sintering temperature is lowered, the chemical activity is increased, and the corrosion resistance is enhanced. Therefore, the properties of force, heat, sound, light, and electromagnetic properties exhibited by nanomaterials are often different from those exhibited by the substance in the coarse crystal state. Compared with traditional crystalline materials, nanomaterials have high strength-hardness, high diffusivity, high plasticity-toughness, low density, low elastic modulus, high electrical resistance, high specific heat, high thermal expansion coefficient, low thermal conductivity, strong Soft magnetic properties. These special properties make nanomaterials widely used in high mechanical performance environments, photothermal absorption, nonlinear optics, magnetic recording, special conductors, molecular sieves, ultramicro composite materials, catalysts, heat exchange materials, sensitive components, sintering aids, Lubricants and other fields.

In Europe, America and Japan, many manufacturers have successively industrialized nano powder and nano components, and they are in a leading position in the world in nano synthesis, nano device precision processing, nano biotechnology, and nano basic theory. my country has also established some nanomaterial development companies under the influence of the international environment. At present, there are more than 20 research institutions in more than 50 universities and more than 300 companies engaged in nano research in my country. More than 10 nanotechnology production lines have been established. There are more than 100 companies, mainly producing primary products such as ultra-fine nano-powders and biochemical nano-powders.

After decades of research and exploration of nanotechnology, scientists have now been able to manipulate individual atoms in the laboratory, and nanotechnology has developed by leaps and bounds. The application research of nanotechnology is developing rapidly in the fields of semiconductor chips, cancer diagnosis, new optical materials and biomolecular tracking.

Although nanotechnology as a whole is still in the stage of experimental research and small-scale production, from a historical perspective: the countries that paid attention to micron technology in the 1970s have now become developed countries. Countries that focus on developing nanotechnology today are likely to become advanced countries in the 21st century. Nanotechnology is both a severe challenge and a rare opportunity for us. We must pay more attention to the research of nanotechnology and nanobasic theory, so as to lay a solid foundation for my country's economic take-off in the 21st century. The entire human society will undergo fundamental changes due to the development and commercialization of nanotechnology.

At present, there are various methods for preparing nano-powders, including liquid-phase method, solid-phase method and gas-phase method, and the liquid-phase method has become the preferred method for industrial production because of its mild reaction conditions and easy control. In the process of preparing ultrafine powders, each stage can lead to particle growth and the formation of agglomerates. Compared with other preparation methods, the hydrothermal method provides a physical and chemical environment for the reaction and crystallization of various precursors that cannot be obtained under normal pressure conditions. The formation of powder has gone through the process of dissolution and crystallization. In the preparation process, high-temperature burning treatment can also be avoided, which avoids the possible hard agglomeration of the powder, and the prepared powder has high purity, good dispersibility, and less pollution and less energy consumption.

Contents of the invention

The proposal of the present invention aims at synthesizing high-purity nanomaterial powders by using a low-temperature hydrothermal synthesis method based on two-component diffusion control.

Technical solution of the present invention is realized like this:

(1) The cation exchange fiber or ion exchange resin is pretreated with acid and alkali, and washed with deionized water to make the conductivity <100 μS/cm;

(2) Add a certain concentration of precursor salt ion solution into the fiber/resin solution, and gently stir for pre-exchange of ions to transform the fiber/resin;

(3) adding a certain concentration of urea solution into the fiber/resin system after transformation, stirring evenly, and then carrying out hydrothermal treatment under certain temperature and time conditions;

(4) The product is ultrasonically separated from fibers, filtered, centrifuged, dried, and then roasted.

The optimal process parameters of the preparation process are: the pre-exchange degree of metal ions on the fiber/resin is 80%, the synthesis temperature is 90°C, the synthesis time is 8-24h, the drying temperature is 80°C, and the drying time is 24h.

Compared with the prior art, the present invention has the advantages of:

(1) The method removes impurities during the synthesis process through ion-exchange surface reaction, eliminating the washing process.

(2) No need to add surfactant in the synthesis process, highly dispersed, non-agglomerated, high-purity nanomaterial powder can be obtained.

(3) The fiber/resin used can be recycled and reused. Compared with the traditional hydrothermal synthesis method, this experiment can achieve the same particle size and higher purity at a lower temperature, which is a new energy-saving and environment-friendly method.

Description of drawings

Figure 1: SEM images of fresh ion exchange fibers;

Figure 2: SEM image of spherical basic cerium carbonate on the fiber surface;

Figure 3: Scanning electron microscope SEM image of flaky basic cerium carbonate on the fiber surface;

Figure 4: SEM image of rod-shaped basic cerium carbonate on the fiber surface;

Figure 5: X-ray diffraction XRD pattern of the nano-cerium oxide sample calcined at 400°C for 4 hours.

Detailed ways

As shown in Figure 1 to Figure 5. A new method for preparing nanomaterials is characterized in that it is a low-temperature hydrothermal synthesis method based on two-component diffusion control. The metal composition of the nanomaterial is one or more transition metal elements including iron, cobalt, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, and lanthanide elements such as lanthanum, cerium, One or more rare earth metal elements in praseodymium, neodymium, etc., and the synthesis products are their corresponding carbonates, basic carbonates and their oxides. Its technological process mainly includes the following steps:

(1) The cation exchange fiber or ion exchange resin is pretreated with acid and alkali, and washed with deionized water to make the conductivity <100 μS/cm;

(2) Add a certain concentration of precursor salt ion solution into the fiber/resin solution, and gently stir for pre-exchange of ions to transform the fiber/resin;

(3) adding a certain concentration of urea solution into the fiber/resin system after transformation, stirring evenly, and then carrying out hydrothermal treatment under certain temperature and time conditions;

(4) The product is ultrasonically separated from the fiber, filtered, centrifuged, dried, and then roasted.

Below in conjunction with embodiment for further explanation.

Example 1

Pre-exchange of cation exchange fibers: at room temperature, take 2.0 g of pretreated (GB/T5476-1996) strongly acidic ion exchange fibers in a 250 ml beaker, add 40 ml of 0.01mol/L cerium nitrate solution, and supplement with deionized water to 100ml, magnetically stirred at 200r/min for 3h, then washed with deionized water until the conductivity of the effluent was <100μS/cm, filtered and dried at 80°C for 24h.

Example 2

The preparation of spherical basic cerium carbonate: get the cerium-type strongly acidic ion-exchange fiber pre-exchanged according to Example 1, add 20ml 1.0mol/L urea solution to supplement to 70ml, ultrasonic 3h at room temperature, transfer to 100ml hydrothermal reaction kettle Keep in an oven at 90°C for 24 hours, filter after cooling down to room temperature, wash with water until neutral, and dry at 80°C for 24 hours.

Example 3

Pre-exchange of cation exchange fibers: at room temperature, take 2.0 g of pretreated (GB/T5476-1996) strongly acidic ion exchange fibers in a 250 ml beaker, add 40 ml of 0.05 mol/L cerium nitrate solution, and supplement with deionized water to 100ml, magnetically stirred at 200r/min for 3h, then washed with deionized water until the conductivity of the effluent was <100μS/cm, filtered and dried at 80°C for 24h.

Example 4

Preparation of flaky basic cerium carbonate: Get 2.0 g of cerium-type strongly acidic ion-exchange fiber pre-exchanged according to Example 3, add 20 ml of 1.0 mol/L urea solution to supplement to 70 ml, ultrasonicate at room temperature for 3 hours, and transfer to 100 ml of water In a thermal reaction kettle, keep in an oven at 90°C for 8 hours, filter after cooling down to room temperature, wash with water until neutral, and dry at 80°C for 24 hours.

Preparation of rod-shaped basic cerium carbonate: Take 2.0 g of cerium-type strongly acidic ion-exchange fibers pre-exchanged according to Example 3, add 20 ml of 1mol/L urea solution to supplement to 70 ml, ultrasonicate for 3 hours at room temperature, and transfer 100 ml of hydrothermal reaction In the kettle, keep in an oven at 90°C for 16h, filter after cooling down to room temperature, wash with water until neutral, and dry at 80°C for 24h.

Example 5

Preparation of nano-cerium oxide: Take 2.0 g of cerium-type strongly acidic ion-exchange fibers pre-exchanged according to Example 3, add 20 ml of 1mol/L urea solution to supplement to 70 ml, ultrasonicate for 3 hours at room temperature, and transfer to a 100 ml hydrothermal reaction kettle , kept in an oven at 90°C for 16h, filtered after cooling down to room temperature, washed with water until neutral, dried at 80°C for 24h, and calcined at 400°C for 4h.

Claims (3)

1. A high-purity nanomaterial, characterized in that: the metal composition of the nanomaterial is composed of one or more of iron, cobalt, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold Transition metal elements and one or more rare earth metal elements in lanthanide elements such as lanthanum, cerium, praseodymium, neodymium, etc., and the synthesis products are their corresponding carbonates, basic carbonates and their oxides. 2. a preparation method of high-purity nano-material as claimed in claim 1, is characterized in that: comprises the following steps: (1) The cation exchange fiber or ion exchange resin is pretreated with acid and alkali, and washed with deionized water to make the conductivity <100 μS/cm; (2) Add a certain concentration of precursor salt ion solution into the fiber/resin solution, and gently stir for pre-exchange of ions to transform the fiber/resin; (3) adding a certain concentration of urea solution into the fiber/resin system after transformation, stirring evenly, and then carrying out hydrothermal treatment under certain temperature and time conditions; (4) The product is ultrasonically separated from fibers, filtered, centrifuged, dried, and then roasted. 3. according to the preparation method of the described nanometer material of claim 2, it is characterized in that the optimal process parameter of described preparation method is: the pre-exchange degree of metal ion on fiber/resin is 80%, synthesis temperature 90 ℃, synthesis time 8-24h, the drying temperature is 80°C, and the drying time is 24h.

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