CN102381844B - Method for modifying hollow glass microspheres by chemical precipitation process - Google Patents

Abstract

The invention discloses a method for modifying hollow glass microspheres by using a chemical precipitation method. First, according to the mass-volume concentration, 10-20 g/L hollow glass microspheres are weighed and added to the degreasing liquid. Stir at 100°C, react for 20-30 minutes, filter and wash the hollow glass beads, and dry at 110°C for 1-2 hours; then use ferrous chloride and ferric chloride on the surface of the hollow glass beads Coated with magnetic nano ferric oxide particle film. The method of the present invention adopts the chemical precipitation method to directly coat a layer of magnetic nano-ferric oxide particle film on the surface of the hollow glass microspheres while preparing the magnetic nanometer ferric oxide particles, so as to endow the hollow glass microspheres with magnetic properties. It saves raw materials and is easy to operate. The test results show that the hollow glass microspheres modified by the magnetic nano ferroferric oxide have excellent magnetic properties and certain bonding fastness, which can meet the actual needs.

Description

Method for modifying hollow glass microspheres by chemical precipitation

technical field

The invention belongs to the technical field of functional inorganic non-metallic materials, and relates to a method for modifying hollow glass microspheres, in particular to a method for modifying hollow glass microspheres by chemical precipitation.

Background technique

Iron tetroxide (Fe ₃ O ₄ ) is an important spinel-like ferrite, which has many optical, electrical, acoustic, thermal and magnetic properties different from conventional materials, and is the most widely used soft magnetic material One of them is often used as recording materials, pigments, magnetic fluid materials, catalysts, magnetic polymer microspheres and electronic materials, etc. It also has good application prospects in the fields of biotechnology and medicine. At present, the methods for preparing magnetic nano-ferric oxide particles mainly include hydrothermal reaction method, neutralization precipitation method, chemical co-precipitation method, precipitation oxidation method and microwave radiation method, among which the chemical precipitation method is environmentally friendly and has high purity. The nanoparticles are uniform, well-dispersed, do not need to be burned at high temperature, simple to operate, and easy to realize industrial production. Hollow glass microspheres are hollow glass spheres with a small size, which have the advantages of light weight, low thermal conductivity, compression resistance, high dispersion, sound insulation, electrical insulation and thermal stability, etc., and are developed in recent years. , A new lightweight material with excellent performance. Taking advantage of the light weight and hollow characteristics of hollow glass microspheres, the surface modification treatment can be used to obtain new materials with special properties (such as wave absorption, light reflection, wear resistance and catalysis, etc.). At present, there is no relevant technology for coating hollow glass microspheres with magnetic nano ferric oxide particle films by chemical precipitation. The existing modification methods mainly use the chemical co-precipitation method to coat a layer of spinel-type ferrite or magnetoplumbite-type ferrite on the surface of hollow glass microspheres. However, the requirements for process equipment are high and it is not easy to achieve industrialization.

Contents of the invention

The object of the present invention is to provide a method for modifying hollow glass microspheres by chemical precipitation, which solves the problem that the hollow glass microspheres obtained by the existing modification methods have no magnetic properties or poor magnetic properties.

The technical solution adopted in the present invention is to adopt the chemical precipitation method to modify the method for hollow glass microspheres, specifically according to the following steps:

Step 1: According to the mass-volume concentration, weigh 10-20g/L hollow glass microspheres and add them to the degreasing liquid. The beads were filtered, washed with water, and dried at 110°C for 1-2 hours;

Step 2: According to the total iron concentration of 0.01-0.1mol/L, the mass ratio of ferrous chloride to ferric chloride is Fe ²⁺ : Fe ³⁺ =1:4-4:1 and weigh ferrous chloride and ferric chloride Ferric chloride is dissolved in deionized water to obtain a mixed solution of ferrous iron and ferric iron, and then the hollow glass microspheres obtained in step 1 are immersed in the mixed solution for 1-10 minutes at a temperature of 10-50°C, Add dropwise ammonia solution with a mass concentration of 28% while stirring, keep the pH value at 9-11, react at a constant temperature at a rate of 100-900r/min for 1-3h, separate and filter the hollow glass microspheres after the reaction is completed, and use Repeated washing with deionized water and absolute ethanol, and drying in a vacuum oven at 60°C for 30-60min to complete the modification of the hollow glass microspheres.

The present invention is also characterized in that,

Wherein the degreasing liquid in step 1, according to mass-volume concentration, is dissolved in the sodium silicate of the sodium hydroxide of 70g/L, the sodium carbonate of 25g/L, the trisodium phosphate of 25g/L and 7.5g/L Made from ionized water.

The beneficial effect of the present invention is that, while preparing magnetic nano-ferric oxide particles by chemical precipitation method, a layer of magnetic nano-ferric oxide particle film is directly coated on the surface of hollow glass microspheres to endow the hollow glass microspheres with magnetic properties. , by controlling the reaction temperature and time, the ratio of the amount of ferrous iron to ferric iron, the concentration of total iron and other process parameters, the finishing process is optimized. This method saves raw materials and is easy to operate. The test results show that the hollow glass microspheres modified by the magnetic nano ferroferric oxide have excellent magnetic properties and certain bonding fastness, which can meet the actual needs.

Description of drawings

Fig. 1 is the scanning electron microscope photograph before hollow glass microsphere magnetic nano iron ferric oxide is modified;

Fig. 2 is the scanning electron micrograph after adopting the method of the present invention to hollow glass microsphere coating magnetic nano iron ferric oxide modification;

Fig. 3 is the X-ray diffraction spectrogram after adopting the method of the present invention to hollow glass microspheres coating magnetic nano iron ferric oxide modification;

Fig. 4 is the hysteresis curve after the method of the present invention is used to modify the hollow glass microspheres coated with magnetic nano ferric oxide.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention adopts chemical precipitation method to carry out the method for modifying hollow glass microspheres, specifically implements according to the following steps:

Step 1: according to mass-volume concentration, take the sodium hydroxide of 70g/L, the sodium carbonate of 25g/L, the trisodium phosphate of 25g/L and the sodium silicate of 7.5g/L and be dissolved in deionized water, obtain deionized water Oil solution, heated to 80-100°C; weigh 10-20g of hollow glass microspheres, add them to 1L degreasing solution, use mechanical stirring method to fully disperse the hollow microspheres in the degreasing solution, react for 20-30min, filter, Washing with water, and finally drying the filtered hollow microspheres at 110° C. for 1-2 hours.

Step 2: According to the total iron concentration of 0.01-0.1mol/L, the mass ratio of ferrous chloride to ferric chloride is Fe ²⁺ : Fe ³⁺ =1:4-4:1 and weigh ferrous chloride and ferric chloride Ferric chloride, dissolved in deionized water to obtain a mixed solution of ferrous iron and ferric iron, then soak the hollow microspheres obtained in step 1 in the mixed solution at 10-50°C for 1-10min, and slowly drop while stirring Add an ammonia solution with a mass concentration of 28%, so that the pH of the solution is 9-11, treat it at a constant temperature at a rate of 100-900r/min for 1-3h, separate and filter the hollow glass microspheres after the reaction is completed, and use deionized water and no After washing with water and ethanol for several times, drying in a vacuum oven at 60°C for 30-60 minutes, the hollow glass microspheres are coated with a thin film of magnetic nano ferric oxide particles.

Figure 1 and Figure 2 are scanning electron micrographs before and after modification of hollow glass microspheres coated with magnetic nano iron ferric oxide. It can be seen that the surface of the unmodified hollow glass microspheres is very clean, and no other substances are attached. The surface of the modified hollow glass microspheres is covered with a layer of film-like substances, and some fine particles are also scattered. High-power electron microscope photos It shows that the film is composed of nanoscale particles. Fig. 3 is the X-ray diffraction spectrogram of hollow glass microspheres coated with magnetic nano iron ferric oxide modified. It can be seen that the nano-ferric oxide particles coated on the surface of the modified hollow glass microspheres have a cubic inverse spinel structure, which is in phase with the magnetite Fe ₃ O ₄ (No.19-0629) in the standard map JCPDS. unanimous. Fig. 4 is the hysteresis curve of the surface-coated nano ferric oxide hollow microspheres after modification. The test results show that the hollow glass microspheres coated with nano-ferric oxide have superparamagnetism.

The hysteresis loop of the coated nano-Fe3O4 hollow glass microspheres was measured with a VSM multifunctional vibrating sample magnetometer (Quantum Design, USA), and the saturation magnetization and residual magnetization were calculated.

The beneficial effect of the present invention is explained from the principle aspect:

1. The present invention controls the total iron concentration, the mass ratio of ferrous chloride to ferric chloride, the pH value of the solution, the reaction temperature, the reaction time and the stirring speed, so that the iron ferric oxide film coated on the surface of the hollow glass microsphere is uniform. , the particles are nano-scale, good fastness to the hollow glass microspheres, and has a certain degree of magnetism. Because the total iron concentration, the ratio of ferrous chloride to ferric chloride mass, the pH value of the solution, the reaction temperature and time, and the stirring speed all affect the magnetic properties, purity, crystallization degree, morphology and particle size of ferric oxide . When the total iron concentration is 0.01-0.1mol/L, the surface of the hollow glass microspheres can be coated with a certain thickness of magnetic nano-ferric oxide particle film, and the particles rarely agglomerate, and at the same time, too much nano-particles will not be deposited in the solution. Particles are firmly combined with hollow glass microspheres; when it is less than 0.01mol/L, there are too few iron ions in the solution, and a continuous film will not be formed on the surface of hollow microspheres, which will affect the magnetic properties; when it is greater than 0.1mol/L, the concentration of iron ions If it is too large, it will easily cause waste. The magnetic nano-ferric oxide particle film adhered to the surface of the hollow glass microsphere is too thick, the adhesion fastness is not good, and the nano-particles are easy to fall off during use.

2. When the mass ratio of ferrous chloride to ferric chloride is 1:4-4:1, the surface of hollow glass microspheres can be coated with a certain thickness of film, and the nanoparticles and hollow glass microspheres are firmly combined; when it is less than 1: 4, the amount of ferric ions is too large, and impurities containing more ferric iron are prepared, and the magnetic properties are very weak; when it is greater than 4:1, the amount of ferric ions is too small, and impurities containing more ferrous iron are prepared. impurities, the magnetic properties are also very weak.

3. When the reaction temperature is controlled at 10-50°C, magnetic nano-ferric oxide particles can be produced; when the temperature is lower than 10°C, the growth of magnetic nano-ferric oxide is very slow; when the temperature is higher than 50°C, the magnetic nano-Fe4 Iron oxide particles are very large.

4. When the pH value of the solution is controlled at 5-11, nanometer ferric oxide particles can be generated; when the pH value is less than 5, the generated ferric oxide particles have no magnetic properties; The particles are very weakly magnetic.

5. Reaction time and stirring speed mainly affect the degree of crystallization, crystal morphology and size of Fe3O4. When the reaction time is controlled at 1-3h, the magnetic nano-ferric oxide particle film can be generated on the surface of the hollow glass microsphere; Affect the degree of crystallization of magnetic nano ferroferric oxide, and the magnetic properties are not good; when it is longer than 3 hours, the generated magnetic nano ferric ferric oxide particles will obviously agglomerate, the particle size will increase significantly, the surface will be rough and uneven, and the particles will easily fall off.

Example 1

Weigh 2 g of hollow glass microspheres, add them to 100 ml of oil-removing liquid, stir and react at 80°C for 20 minutes, then filter and wash with water, and dry the filtered hollow microspheres at 110°C for 1 hour. Weigh a certain amount of ferrous chloride and ferric chloride, dissolve them in deionized water, control the total iron concentration to 0.01mol/L, and the mass ratio of ferrous chloride to ferric chloride is 1:4, add pre- Treat the treated hollow glass microspheres at 10°C for 1 min, slowly add ammonia water with a concentration of 28% dropwise while stirring, so that the pH value of the solution is 5, and stir at a constant temperature of 100r/min for 1h. After the reaction is completed, The hollow microspheres were separated and filtered, washed with deionized water until neutral, and dried in a vacuum oven at 60°C for 30 minutes.

The saturation magnetization of the coated magnetic nano-ferric iron tetroxide hollow glass microspheres is 12emu/g, and the residual magnetization is zero.

Example 2

Weigh 1 g of hollow glass microspheres, add them to 100 ml of oil-removing liquid, stir and react at 100°C for 30 minutes, then filter and wash with water, and dry the filtered hollow microspheres at 110°C for 2 hours. Weigh a certain amount of ferrous chloride and ferric chloride, dissolve them in deionized water, control the total iron concentration to 0.1mol/L, and the mass ratio of ferrous chloride to ferric chloride is 4:1, add pre- Treat the treated hollow glass microspheres at 50°C for 10 minutes, slowly add ammonia water with a concentration of 28% while stirring, so that the pH of the solution is 11, treat at a constant temperature of 900r/min for 3 hours, and separate after the reaction is completed. The microbeads were filtered out, washed with deionized water until neutral, and dried in a vacuum oven at 60°C for 60 min.

The saturation magnetization of the coated magnetic nano-ferric iron tetroxide hollow glass microspheres is 45 emu/g, and the residual magnetization is zero.

Example 3

Weigh 1.5 g of hollow glass microspheres, add them to 100 ml of oil-removing liquid, stir and react at 95°C for 25 minutes, then filter and wash with water, and dry the filtered hollow microspheres at 110°C for 1.5h. Weigh a certain amount of ferrous chloride and ferric chloride, dissolve them in deionized water, control the total iron concentration to 0.05mol/L, and the mass ratio of ferrous chloride to ferric chloride is 2:1, add pre- Treat the treated hollow glass microspheres at 30°C for 5 minutes, slowly add ammonia water with a concentration of 28% dropwise while stirring, so that the pH value of the solution is 9, treat at a constant temperature of 500r/min for 2 hours, and separate after the reaction is completed. The hollow microspheres were filtered out, washed with deionized water until neutral, and dried in a vacuum oven at 60°C for 40 minutes.

The saturation magnetization of the coated magnetic nano-ferric iron tetroxide hollow glass microspheres is 23emu/g, and the residual magnetization is zero.

Claims (2)

1. adopt the chemical precipitation method to carry out the method that hollow glass microsphere is modified, it is characterized in that, specifically implement according to the following steps: Step 1: According to the mass-volume concentration, weigh 10-20g/L hollow glass microspheres and add them to the degreasing liquid. The beads were filtered, washed with water, and dried at 110°C for 1-2 hours; Step 2: According to the total iron concentration of 0.01-0.1mol/L, the mass ratio of ferrous chloride to ferric chloride is Fe2+:Fe3+=1:4-4:1 and weighs ferrous chloride and ferric chloride, Dissolve in deionized water to obtain a mixed solution of ferrous iron and ferric iron, then immerse the hollow glass microspheres obtained in step 1 in the mixed solution for 1-10 minutes at a temperature of 10-50°C, and drop while stirring Add ammonia solution with a mass concentration of 28%, keep the pH value at 9-11, react at a constant temperature at a rate of 100-900r/min for 1-3h, separate and filter the hollow glass microspheres after the reaction is completed, and use deionized water and Repeated washing with absolute ethanol, and drying in a vacuum oven at 60°C for 30-60 minutes to complete the modification of the hollow glass microspheres. 2. the method for modifying hollow glass microspheres by chemical precipitation according to claim 1, characterized in that, the degreasing liquid in the step 1, according to the mass-volume concentration, consists of 70g/L of hydrogen Sodium oxide, 25g/L sodium carbonate, 25g/L trisodium phosphate and 7.5g/L sodium silicate are dissolved in deionized water.

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