CN118145658A - Method for efficiently preparing micron-sized silicon dioxide microspheres by using water glass through reversed-phase suspension dispersion - Google Patents

Abstract

The invention discloses a method for efficiently preparing micron-sized silica microspheres by using water glass through reverse phase suspension dispersion. The principle of preparing weak acid by strong acid is adopted, different types of silicic acid compounds and different organic phases are mixed in proportion, different types/concentrations of acid are added dropwise under high-speed dispersion conditions for reaction, and the silica microspheres are dispersed for a period of time after precipitation, and monodispersed micron-sized amorphous silica microspheres of different particle sizes are obtained by precipitation, washing and drying. The raw material water glass used in the invention has low cost, no emulsifier is required, the operation process is greatly simplified, the organic phase can be recycled, and the entire preparation process is simple to operate, low in energy consumption, low in cost, and green and environmentally friendly. The micron-sized silica microspheres prepared by the invention contain a large number of hydroxyl groups, have a large specific surface area, can regulate the particle size, and have a high sphericity. The method has great advantages and application prospects in the preparation of micron-sized silica microspheres.

Description

A method for efficiently preparing micron-sized silica microspheres by using water glass through reverse suspension dispersion

Technical Field

The invention relates to the technical field of silicon dioxide microsphere preparation, and in particular to a method for efficiently preparing micron-sized silicon dioxide microspheres by using water glass through reverse phase suspension dispersion.

Background technique

Silica microspheres show excellent mechanical, thermal, chemical (especially acid resistance) and biological stability. Composite materials made of silica microspheres are used in many monitoring fields, including the detection of biomolecules, ions and compounds. In particular, micron-sized silica microspheres have a wide range of uses and can be used as reinforcing materials in different media to improve the strength, hardness, chemical stability, wear resistance, corrosion resistance and weather resistance of the matrix. For example, monodispersed silica microspheres are widely used in display panels to stably support the gap space in liquid crystals and act as a skeleton. In addition, silica microspheres have large pores, low toxicity and high specific surface area, making them ideal adsorbents and chemical carriers. In addition, the content of hydroxyl groups on the surface of amorphous silica is very high, which provides a variety of possibilities for surface modification.

At present, the methods for preparing micron-sized silica microspheres are mainly divided into physical methods and chemical methods. The physical method includes mechanical grinding, spray drying and high-temperature spheroidization; the chemical method includes template method, gas phase method and precipitation method. In the physical method, irregularly shaped silica raw materials are transformed into spheres through a series of physical methods. In the chemical method, organic silicon or water glass is used as raw materials, and silica microspheres are obtained through a series of chemical modifications. Compared with the physical method, the main advantages of the chemical synthesis process are low energy consumption and high purity. However, most chemical synthesis methods use organic silicon as a silicon source, such as ethyl orthosilicate, which is expensive and the byproduct of the reaction is organic matter, which increases the cost of post-reaction processing and complicates downstream processing. Compared with the precipitation method, the evaporation method and template method use cheap water glass as a silicon source, but there are also problems such as complex ion exchange process and poor product quality. Therefore, it is urgent to develop a low-cost and low-energy consumption process to synthesize micron-sized silica microspheres to achieve the goal of "low carbon energy saving".

At present, the process of synthesizing silica microspheres by precipitation from water glass as raw material is rare. In industry, silica microspheres synthesized from tetraethyl orthosilicate (TEOS) are almost all used because the silica microspheres produced by this process have good sphericity, low density, and easy size control. Although the synthesis of silica microspheres from water glass has the advantages of low raw material cost, low productivity and environmental protection, the silica microspheres synthesized by this technology have high agglomeration degree, spherical particles cannot be monodispersed, and emulsifiers are required. The organic phase after preparation is difficult to recycle, so industrial production is very difficult. Therefore, it is necessary to develop a kind of silica microspheres with water glass as raw material, greatly simplify the operation process, and realize the efficient preparation process of organic phase recycling.

Summary of the invention

In order to solve the problems existing in the prior art, the present invention provides a method for efficiently preparing micron-sized silica microspheres by using water glass through reverse suspension dispersion. The present invention can obtain micron-sized silica microspheres with excellent sphericity, controllable particle size and pore volume, and can realize the recycling of the organic phase after preparation. The entire preparation process is simple to operate, low in energy consumption, low in cost, and green and environmentally friendly, thereby solving the problems mentioned in the above-mentioned background technology.

To achieve the above object, the present invention provides the following technical solution: a method for efficiently preparing micron-sized silica microspheres by using water glass through reverse suspension dispersion, comprising the following steps:

S1, mixing liquid water glass and organic phase in a certain proportion, dispersing and aging at high speed to form a reaction precursor;

S2: adding an acidic solution dropwise to the precursor dispersed during high-speed stirring;

S3: After the silica microspheres are precipitated, continue to disperse and age for a period of time;

S4: After precipitation, washing and drying, monodisperse micron-sized silica microspheres can be obtained.

Preferably, the liquid water glass in step S1 comprises sodium water glass Na ₂ O·nSiO ₂ , potassium water glass K ₂ O·nSiO ₂ and/or potassium/sodium water glass (K/Na) ₂ O·nSiO ₂ with different moduli n, wherein the range of the different moduli n is 2.3-3.3.

Preferably, the organic phase in step S1 is a mixed liquid of fats contained in animals and plants or mineral hydrocarbons, including one or a mixture of several of engine oil, silicone oil, vacuum pump oil, petroleum, gasoline, kerosene, peanut oil, soybean oil or sunflower oil.

Preferably, in step S1, the volume ratio of liquid water glass to organic phase is 1:1-200.

Preferably, in step S1, the volume ratio of liquid water glass to organic phase is 1:3-50.

Preferably, the dispersion speed in step S1 is 100 to 5000 r/min, and the aging time is 1 to 60 min.

Preferably, the dispersion speed in step S1 is 500-3000 r/min, and the aging time is 5-40 min.

Preferably, the mass percentage concentration of the acidic liquid in step S2 is 1% to pure solvent, and the dripping rate is 0.05-100 mL min ^-1 ; the acidic liquid is acetic acid, citric acid, malic acid, formic acid, acetic propionic acid, carbonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, ammonium chloride or ethyl acetate.

Preferably, in step S2, the mass percentage concentration of the acidic liquid is 5% to 60%, and the dripping rate is 0.5 to 30 mL min ^-1 .

Preferably, the dispersion speed in step S3 is 100 to 5000 r/min, and the dispersion time is 1 to 60 min.

Preferably, the dispersion speed in step S3 is 500-3000 r/min, and the dispersion time is 10-30 min.

Preferably, the drying temperature in step S4 is 20-200° C., and the drying time is 20 min-72 h.

Preferably, the drying temperature in step S4 is 80-120° C., and the drying time is 20 min-48 h.

Preferably, the monodisperse micron-sized amorphous silica microspheres have a particle size of 1 to 500 μm, a specific surface area of 5 to 800 m ² /g, and a pore volume of 0.1726 to 0.43 cm ³ /g.

Preferably, the monodisperse micron-sized amorphous silica microspheres have a particle size of 20 to 300 μm, a specific surface area of 100 to 400 m ² /g, and a pore volume of 0.17 to 0.2624 cm ³ /g.

Preferably, in the method for preparing micron-sized silica microspheres, no emulsifier is needed, and the organic phase can be recycled. After 30 to 50 cycles, the prepared monodisperse micron-sized amorphous silica microspheres still have a particle size of 1 to 500 μm, a specific surface area of 5 to 800 m ² /g, and a pore volume of 0.17 to 0.43 cm ³ /g.

The beneficial effects of the present invention are as follows: in view of the problems existing in the current precipitation method for generating silica microspheres using water glass as raw material, the present invention develops a method for efficiently preparing micron-sized silica microspheres using water glass through reverse phase suspension dispersion technology, adopts the principle of strong acid to weak acid, utilizes the characteristics of water glass reacting to generate silicic acid under acidic conditions, and supersaturated silica precipitates silica, and the specific operation is carried out according to the following steps: different types of silicic acid compounds and different organic phases are mixed in proportion, different types/concentrations of acid are added dropwise under high-speed dispersion conditions for reaction, and after the silica microspheres are precipitated, they are continued to be dispersed for a period of time, and monodispersed micron-sized amorphous silica microspheres of different particle sizes are obtained through precipitation, washing, and drying. Compared with the current preparation technology, the method for preparing silica of the present invention has the following advantages: the whole process flow is simple, the spheres are formed once, the equipment requirements are low, no high temperature conditions are required, the energy consumption of the preparation process is greatly reduced, the raw materials are cheap, ten times lower than the current commercial raw material ethyl orthosilicate, the organic phase can be recycled, and the whole preparation process is green and environmentally friendly. The silica microspheres prepared by the present invention are monodisperse, have good sphericity, have large pore volume and specific surface area, and have high yield; the particle size is controllable (1-400 μm) and the particle size distribution is uniform; the pore volume is large and the pore size distribution is uniform; and the silica microspheres have excellent properties such as high strength, high temperature resistance, corrosion resistance, and stable chemical properties. The method has great advantages and application prospects in the preparation of silica microspheres.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an optical microscope image of silica microspheres prepared from water glass with different moduli as raw materials in Examples 1-4;

FIG2 is a particle size distribution diagram of silica microspheres prepared from water glasses with different moduli as raw materials in Examples 1-4;

3 is an optical microscope image of silica microspheres prepared using potassium and potassium/sodium water glass as raw materials in Example 5-6;

FIG4 is an optical microscope image of silica microspheres prepared in a medium of rapeseed oil, soybean oil, peanut oil and dimethyl silicone oil in Examples 7-10;

5 is an optical microscope image of silica microspheres prepared by dropwise addition of carbonic acid, sulfuric acid, hydrochloric acid and a mixture of hydrochloric acid/sulfuric acid as raw materials in Examples 11-14;

FIG6 is an optical microscope image of silica microspheres prepared from the oil medium of Examples 15-16 after the second and fifth cycles;

FIG7 is an X-ray diffraction diagram of silica microspheres prepared under different process parameters in Examples 1, 2, 6 and 10;

FIG8 is an optical microscope image of silica microspheres prepared by adding an emulsifier in Comparative Example 1;

FIG. 9 is a state diagram of the final phase of the system after the reaction of Comparative Example 1 and Example 1 is completed.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Embodiment 1:

(1) 10 mL of sodium water glass slurry with a modulus of 2.3 was added to 500 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 500 r/min for 40 min to make the system into a uniform slurry;

(2) dripping a 25% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 500 r/min at a dripping speed of 2 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 500 r/min for 30 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in Figures 1 and 2, and the average particle size is 91.28 μm, the specific surface area is 243.83 m ² /g, and the pore volume is 0.2675 cm ³ /g. The X-ray diffraction diagram is shown in Figure 7.

Embodiment 2:

(1) 10 mL of sodium water glass slurry with a modulus of 2.3 was added to 30 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 3000 r/min for 5 min to make the system into a uniform slurry;

(2) dripping a 25% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 3000 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 3000 r/min for 10 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 120° C. for 20 min;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in FIG1 , and the average particle size is 83.35 μm, the specific surface area is 234.83 m ² /g, and the pore volume is 0.1726 cm ³ /g.

Embodiment 3:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 30 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 100° C. for 50 min;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in FIG1 , and the average particle size is 114.51 μm, the specific surface area is 176.4867 m ² /g, and the pore volume is 0.432 cm ³ /g.

Embodiment 4:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 60% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 0.5 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 90° C. for 24 h;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in FIG1 , and the average particle size is 104.81 μm, the specific surface area is 40.57 m ² /g, and the pore volume is 0.2624 cm ³ /g.

Embodiment 5:

(1) 10 mL of potassium water glass slurry with a modulus of 2.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in Figure 3. Due to the low viscosity of potassium water glass, potassium water glass is over-dispersed and silica is severely agglomerated.

Embodiment 6:

(1) 10 mL of potassium/sodium water glass slurry with a modulus of 2.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope image of the microsphere is shown in Figure 3, and the X-ray diffraction image is shown in Figure 7.

Embodiment 7:

(1) 10 mL of potassium/sodium water glass slurry with a modulus of 2.3 was added to 100 mL of soybean oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the soybean oil and the resulting product in step (2) are continued to be stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the soybean oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to wash away the soybean oil remaining on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope image of the microspheres is shown in Figure 4.

Embodiment 8:

(1) Add 10 mL of potassium/sodium water glass slurry with a modulus of 2.3 into 100 mL of peanut oil and mix well. Disperse at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry.

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the peanut oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the soybean oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to wash away the peanut oil remaining on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 110° C. for 20 min;

After testing, the optical microscope image of the microspheres is shown in Figure 4.

Embodiment 9:

(1) adding 10 mL of potassium/sodium water glass slurry with a modulus of 2.3 into 100 mL of sunflower oil and mixing them evenly, and dispersing them at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the sunflower seed oil and the resulting product in step (2) are continued to be stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the sunflower seed oil and the resulting product in step (3) to obtain silica microspheres;

(5) placing the silica microspheres obtained in step (4) in water to wash off the sunflower oil remaining on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope image of the microspheres is shown in Figure 4.

Embodiment 10:

(1) Add 10 mL of potassium/sodium water glass slurry with a modulus of 2.3 into 100 mL of methyl silicone oil and mix well, and disperse at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dripping speed of 2 mL/min;

(3) After the acid solution is dripped, the methyl silicone oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the soybean oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the methyl silicone oil remaining on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 105° C. for 2 h;

After testing, the optical microscope image of the microsphere is shown in FIG4 , and the X-ray diffraction image is shown in FIG7 .

Embodiment 11:

(1) 10 mL of sodium water glass slurry with a modulus of 2.3 was added to 30 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 3000 r/min for 5 min to make the system into a uniform slurry;

(2) adding a 25% by mass carbonate solution at a dropping speed of 2 mL/min into the slurry of step (1) at a dispersion speed of 3000 r/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 3000 r/min for 10 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 120° C. for 20 min;

After testing, the microsphere optical microscope and particle size distribution photos are shown in Figure 5, Example 12:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) adding a 25% by mass sulfuric acid solution at a dropping speed of 0.5 mL/min into the slurry of step (1) at a dispersion speed of 2500 r/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 90° C. for 24 h;

After testing, the microsphere optical microscope and particle size distribution photos are shown in Figure 5, Example 13:

(1) 10 mL of sodium water glass slurry with a modulus of 2.3 was added to 500 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 500 r/min for 40 min to make the system into a uniform slurry;

(2) dripping a 5% by mass hydrochloric acid solution into the slurry of step (1) at a dispersion speed of 500 r/min at a dropping speed of 2 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 500 r/min for 30 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope and particle size distribution photos of the microspheres are shown in Figure 5.

Embodiment 14:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system into a uniform slurry;

(2) adding a 5% by mass hydrochloric acid/sulfuric acid mixed solution at a dropping speed of 2 mL/min into the slurry of step (1) at a dispersion speed of 2500 r/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 85° C. for 48 h;

After testing, the optical microscope image of the microspheres is shown in Figure 5.

Embodiment 15:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil (which had been recycled twice) and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 30 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 100° C. for 50 min;

After testing, the optical microscope and particle size distribution photos of the microspheres prepared from the engine oil medium after the second cycle are shown in Figure 6.

Embodiment 16:

(1) 10 mL of sodium water glass slurry with a modulus of 3.3 was added to 100 mL of engine oil (which had been recycled five times) and mixed evenly, and dispersed at a dispersion speed of 2500 r/min for 20 min to make the system a uniform slurry;

(2) dripping a 5% by mass acetic acid solution into the slurry of step (1) at a dispersion speed of 2500 r/min at a dropping speed of 30 mL/min;

(3) After the acid solution is dripped, the engine oil and the resulting product in step (2) are stirred and dispersed (aged) at a dispersion speed of 2500 r/min for 15 min;

(4) filtering the engine oil and the product obtained in step (3) to obtain silica microspheres;

(5) placing the silica microspheres prepared in step (4) in water to clean the residual oil on the surface of the microspheres;

(6) drying the silica microspheres obtained in step (5) in an oven at 100° C. for 50 min;

After testing, the optical microscope and particle size distribution photos of the microspheres prepared with the engine oil medium after the fifth cycle are shown in Figure 6.

Comparative Example 1

(1) 10 mL of sodium water glass slurry with a modulus of 2.3 was added to 500 mL of engine oil and mixed evenly, and dispersed at a dispersion speed of 500 r/min for 40 min to make the system into a uniform slurry;

(2) Add 5 g of sorbitan fatty acid ester (Span-80) to the slurry of step (1) and continue to disperse for 10 min;

(3) dripping a 25% by mass acetic acid solution into the slurry of step (2) at a dispersion speed of 500 r/min at a dropping speed of 2 mL/min;

(4) After the acid solution is dripped, the engine oil and the resulting product in step (3) are continued to be stirred and dispersed (aged) at a dispersion speed of 500 r/min for 30 min;

(5) filtering the engine oil and the product obtained in step (4) to obtain silica microspheres;

(6) placing the silica microspheres prepared in step (5) in water to clean the residual oil on the surface of the microspheres;

(7) drying the silica microspheres obtained in step (6) in an oven at 85° C. for 48 h;

The experimental conditions of Example 1 were adopted, and other variables were not changed, and an emulsifier (SPAN-80) was added. Comparing the two groups of experiments, as shown in FIG8 , the emulsifier will aggravate the degree of agglomeration of the microspheres, forming spherical clusters. In addition, the yield of silica microspheres in the w/o system is only 53%, while the yield in Example 1 can reach 86%. After adding the emulsifier, the final phase is an emulsion, as shown in Comparative Example 1 in FIG9 ; when no emulsifier is added, as shown in Example 1 in FIG9 , the aqueous phase and the organic phase can be separated and reused, and after repeated multiple cycles of experiments, the production of silica microspheres can still be achieved.

In summary, in view of the problems existing in the current precipitation method of generating silica microspheres with water glass as raw material, the present application has developed a method for preparing micron-sized amorphous silica microspheres with water glass as raw material, using the characteristics of water glass reacting to generate silicic acid under acidic conditions, and silicic acid supersaturation precipitating silica, and the specific operation is carried out according to the following steps: First, water glass and organic phase are stirred and dispersed at high speed in a certain proportion to form a reaction precursor solution. Then, an acidic solution is added dropwise to the solution under high-speed stirring to react and precipitate silica microspheres; finally, micron-sized silica microspheres can be obtained after precipitation, washing, and drying. Compared with the current preparation technology, the method for preparing silica of the present invention is simple in the whole process flow, balling is formed once, the equipment requirements are low, no high temperature conditions are required, the energy consumption of the preparation process is greatly reduced, the raw materials are cheap, ten times lower than the current commercial raw material ethyl orthosilicate, and the recycling of solid waste (organic phase can be reused) can be realized, and the whole preparation process is green and environmentally friendly. In addition, the silica microspheres prepared according to the present invention are: monodisperse, good in sphericity, have a large pore volume and specific surface area, and a high yield; the particle size is controllable (5-300 μm) and the particle size distribution is uniform; the pore volume is large and the pore size distribution is uniform; and the silica microspheres have excellent properties such as high strength, high temperature resistance, corrosion resistance, and stable chemical properties. This method has great advantages and application prospects in the preparation of silica microspheres.

Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The method for efficiently preparing the micron-sized silicon dioxide microspheres by using water glass through reversed-phase suspension dispersion is characterized by comprising the following steps of:

s1, mixing liquid water glass and an organic phase according to a certain proportion, and dispersing and ageing at a high speed to form a reaction precursor;

s2: dropwise adding an acidic solution into the precursor dispersed in the high-speed stirring;

S3: continuing dispersing and aging for a period of time after the silica microspheres are separated out;

s4: and precipitating, washing and drying to obtain the monodisperse micron-sized silica microspheres.

2. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the liquid water glass in the step S1 comprises sodium water glass Na ₂O·nSiO₂, potassium water glass K ₂O·nSiO₂ and/or potassium/sodium water glass (K/Na) ₂O·nSiO₂ with different moduli n, wherein the range of the different moduli n is 2.3-3.3.

3. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the organic phase in the step S1 is a mixed liquid of fat or mineral hydrocarbon contained in animals and plants, and comprises one or a mixture of more of engine oil, silicone oil, vacuum pump oil, petroleum, gasoline, kerosene, peanut oil, soybean oil or sunflower seed oil.

4. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: in the step S1, the volume ratio of the liquid water glass to the organic phase is 1:1 to 200.

5. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the dispersion speed in the step S1 is 100-5000 r/min, and the aging time is 1-60 min.

6. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the mass percentage concentration of the acidic liquid in the step S2 is 1% to the pure solvent, and the dripping speed is 0.05-100 mL min ^-1; the acidic liquid is acetic acid, citric acid, malic acid, formic acid, acetic acid propionic acid, carbonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, ammonium chloride or ethyl acetate.

7. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the dispersion speed in the step S3 is 100-5000 r/min, and the dispersion time is 1-60 min.

8. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the drying temperature in the step S4 is 20-200 ℃ and the drying time is 20 min-72 h.

9. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: the particle size of the monodisperse micron-sized amorphous silica microsphere is 1-500 mu m, the specific surface area is 5-800 m ²/g, and the pore volume is 0.17-0.43 cm ³/g.

10. The method for efficiently preparing micron-sized silica microspheres by inverse suspension dispersion using water glass according to claim 1, wherein the method comprises the following steps: in the method for preparing the micron-sized silica microspheres, the organic phase can be recycled without using an emulsifying agent, and the prepared monodisperse micron-sized amorphous silica microspheres have the particle size of 1-500 mu m, the specific surface area of 5-800 m ²/g and the pore volume of 0.17-0.43 cm ³/g after being recycled for 30-50 times.