A method for preparing porous silica microspheres by salting out

Abstract

The application discloses a method for preparing porous silica microspheres by salting-out, and belongs to the field of preparation of silica microspheres. The method comprises the following steps: preparing water glass, inorganic salt, organic solvent, emulsifier and an emulsifying machine, and preparing porous silica microspheres through an emulsification process, a salting-out process, standing separation, ripening and washing and drying. The method for preparing porous silica microspheres by salting-out greatly simplifies the process and process conditions, and makes the pore volume and pore size of the porous silica microspheres controllable.

Description

Technical Field

[0001] This invention belongs to the field of silica microsphere preparation technology, and particularly relates to a method for preparing porous silica microspheres by salting out. Background Technology

[0002] Silica microspheres currently hold a significant position in the cosmetics, chromatographic analysis and detection, and biopharmaceutical preparation and separation processes. The requirements for silica microspheres vary across these fields. The mainstream method for preparing silica microspheres currently involves TEOS hydrolysis to form a core, followed by further hydrolysis to allow growth. This method is costly and cannot produce microspheres larger than 20 μm. Another method is the template method, which involves first preparing polymer microspheres and then hydrolyzing TEOS onto the template microspheres to form silica microspheres. This process is complex and costly. Therefore, we propose a salting-out method for preparing porous silica microspheres. Summary of the Invention

[0003] This invention provides a method for preparing porous silica microspheres by salting out, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing porous silica microspheres by salting out, comprising the following steps:

[0005] S1. Prepare water glass, inorganic salts, organic solvents, emulsifiers, and an emulsifier;

[0006] S2. Emulsification process: Measure 160ml of water glass and inorganic salt. First, heat the water glass to 45℃, then slowly add the inorganic salt until it is completely dissolved. Mix 320ml of organic solvent and 3.2g of emulsifier evenly and heat to 45℃. Then, add the glass solution containing inorganic salt to the organic solvent containing emulsifier. Emulsify at 600rpm for 60min using an emulsifier.

[0007] S3, Salting out process: After the emulsification in step S2 is completed, the temperature of the emulsion system is rapidly reduced to 10°C, and solid silica microspheres are precipitated from the emulsion. Then, the resulting mixed suspension is added to 500 ml of saturated inorganic salt solution and stirred for 1 hour to ensure complete salting out and solidification of the silica microspheres.

[0008] S4. Separation by standing: Let the mixed solution stand. The solution will separate into layers with the organic solvent on the top layer. Take the bottom silica microsphere aqueous solution and filter it.

[0009] S5. Curing and washing: Disperse silica microspheres in an aqueous solution, adjust the pH to 5, then heat the solution to 80°C and keep it warm for 4 hours. Then wash while hot, starting with an ethanol-water solution and then washing with water until the conductivity is <500μs / cm.

[0010] S6. Drying: Then dry in an oven.

[0011] Furthermore, the inorganic salt is one of sodium chloride, sodium sulfate, potassium chloride, calcium chloride, magnesium chloride, or magnesium sulfate.

[0012] Furthermore, the emulsifier is a W / O type emulsifier, belonging to the Span series.

[0013] Furthermore, the porous silica microspheres are adjusted by controlling the speed of the emulsifier, and the particle size is measured by a laser particle size analyzer to determine the particle size distribution and size of the prepared silica microspheres.

[0014] The beneficial effects of this invention are:

[0015] This method uses water glass and inorganic salts as raw materials to prepare porous silica microspheres by salting out, which greatly simplifies the process steps and conditions, and makes the pore volume and pore size of the porous silica microspheres controllable. Detailed Implementation

[0016] To further understand the content, features, and effects of this invention, the following embodiments are provided, along with detailed descriptions.

[0017] Example 1:

[0018] A method for preparing porous silica microspheres by salting out includes the following steps;

[0019] S1. Prepare water glass, inorganic salts, organic solvents, emulsifiers, and an emulsifier;

[0020] S2. Emulsification process: Measure 160ml of water glass (SiO2=20%, n=3.3) and 12g of sodium chloride. First, heat the water glass to 45℃, then slowly add sodium chloride until it is completely dissolved. Mix 320ml of decane and 3.2g of Span 80 evenly and heat to 45℃. Then add the saline glass solution to the organic solvent. Emulsify for 60 minutes at 600rpm in the emulsifier.

[0021] S3, Salting out process: After the emulsification in step S1 is completed, the temperature of the emulsion system is quickly reduced to 10°C, and solid silica microspheres are precipitated from the emulsion. Then, the mixed suspension is added to 500ml of saturated sodium chloride solution and stirred for 1 hour to ensure that the silica microspheres are completely salted out and solidified.

[0022] S4. Separation by standing: Let the mixed solution stand. The solution will separate into layers, with decane on the top layer. Take the bottom silica microsphere aqueous solution and filter it.

[0023] S5. Aging and washing: Disperse the silica microspheres in an aqueous solution, adjust the pH to 5, then heat the solution to 80°C and keep it warm for 4 hours. Then wash while it is hot, starting with washing with an ethanol aqueous solution, and then washing with water until the conductivity is <500μs / cm.

[0024] S6. Drying: The microspheres were then dried in an oven. After washing and drying, the average volumetric particle size was measured to be 47.32 μm by a particle size analyzer. The specific surface area of ​​the silica microspheres was measured to be 210.23 m² / g, the pore volume was 1.80 cm³ / g, and the pore size was 18.93 nm by BJH.

[0025] Example 2:

[0026] S1. Prepare water glass, inorganic salts, organic solvents, emulsifiers, and an emulsifier;

[0027] S2. Emulsification process: Measure 137.6 ml of water glass (SiO2=14%, n=3.3) and 32 g of sodium chloride. First, heat the water glass to 45°C, then slowly add sodium chloride until it is completely dissolved. Mix 320 ml of decane and 3.2 g of Span 80 evenly and heat to 45°C. Then add the saline glass solution to the organic solvent. Emulsify for 60 minutes at 400 rpm using an emulsifier.

[0028] S3, Salting out process: After the emulsification in step S1 is completed, the temperature of the emulsion system is quickly reduced to 10°C, and solid silica microspheres are precipitated from the emulsion. Then, the mixed suspension is added to 500ml of saturated sodium chloride solution and stirred for 1 hour to ensure that the silica microspheres are completely salted out and solidified.

[0029] S4. Separation by standing: Let the mixed solution stand. The solution will separate into layers, with decane on the top layer. Take the bottom silica microsphere aqueous solution and filter it.

[0030] S5. Aging and washing: Disperse the silica microspheres in an aqueous solution, adjust the pH to 5, then heat the solution to 80°C and keep it warm for 4 hours. Then wash while it is hot, starting with washing with an ethanol aqueous solution, and then washing with water until the conductivity is <500μs / cm.

[0031] S6. Drying: The microspheres were then dried in an oven. After drying, the average volumetric particle size was measured to be 45.56 μm using a particle size analyzer. BJH measurements showed that the specific surface area of ​​the silica microspheres was 96.68 m² / g, the pore volume was 1.52 cm³ / g, and the pore size was 36.11 nm.

[0032] Example 3:

[0033] S1. Prepare water glass, inorganic salts, organic solvents, emulsifiers, and an emulsifier;

[0034] S2. Emulsification process: Measure 160ml of water glass (SiO2=20%, n=3.3) and 12g of sodium sulfate. First, heat the water glass to 45℃, then slowly add sodium sulfate to completely dissolve it. Mix 320ml of decane and 3.2g of Span 80 evenly and heat to 45℃. Then add the saline glass solution to the organic solvent. Emulsify for 60 minutes at 600rpm in the emulsifier.

[0035] S3, Salting out process: After the emulsification in step S1 is completed, the temperature of the emulsion system is quickly reduced to 10°C, and solid silica microspheres are precipitated from the emulsion. Then, the mixed suspension is added to 500ml of saturated sodium chloride solution and stirred for 1 hour to ensure that the silica microspheres are completely salted out and solidified.

[0036] S4. Separation by standing: Let the mixed solution stand. The solution will separate into layers, with decane on the top layer. Take the bottom silica microsphere aqueous solution and filter it.

[0037] S5. Aging and washing: Disperse silica microspheres in an aqueous solution and adjust the pH to 5. Then heat the solution to 80°C and keep it warm for 4 hours. Then wash while it is hot. Start washing with an ethanol aqueous solution and then wash with water until the conductivity is <500μs / cm.

[0038] S6. Drying: The microspheres are then dried in an oven. After washing and drying, the average volumetric particle size of the microspheres is 55.89 μm as measured by a particle size analyzer. The specific surface area of ​​the silica microspheres is 182.36 m² / g, the pore volume is 1.89 cm³ / g, and the pore size is 20.33 nm as measured by BJH.

[0039] Table 1. Sizes of silica microspheres in Examples 1-3

[0040]

[0041] As can be seen from the above embodiments, the method of the present invention can prepare porous silica microspheres with a particle size range of 30~500μm and a pore size of more than 30nm, thus expanding the application of porous silica microspheres from the field of chromatographic detection to the field of pharmaceutical separation and purification production.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method of preparing porous silica microspheres by salt precipitation, characterized by: The method comprises the following steps: S1, preparing water glass, inorganic salt, organic solvent, emulsifier and emulsifying machine; S2, emulsification process: measuring 160 ml of water glass and inorganic salt, first heating the water glass to 45 DEG C, then slowly adding the inorganic salt, so that the inorganic salt is completely dissolved, mixing 320 ml of organic solvent and 3.2 g of emulsifier uniformly, while heating to 45 DEG C, then adding the inorganic salt-containing glass solution into the organic solvent containing emulsifier, and emulsifying the machine at a speed of 600 rpm for 60 min; S3, salting-out process: after the emulsification of step S2 is completed, quickly reducing the temperature of the emulsification system to 10 DEG C, and the emulsion is precipitated to form solid silica microspheres, then adding the obtained mixed suspension into 500 ml of saturated inorganic salt solution, and standing and stirring for 1 hour, so that the silica microspheres are completely salting-out and solidified; S4, standing and separating: standing the mixed solution, and the solution is stratified, the organic solvent is in the uppermost layer, and the bottom silica microsphere aqueous solution is taken for filtration; S5, aging and washing: dispersing the silica microspheres in the aqueous solution, adjusting the pH to 5, then heating the solution to 80 DEG C, and keeping the temperature for 4 hours, then washing while hot, starting with ethanol aqueous solution, then washing with water until the conductivity is less than 500 us / cm; S6, drying: then drying in an oven.

2. A method of preparing porous silica microspheres by salt annealing according to claim 1, characterized in that: The inorganic salt is one of sodium chloride, sodium sulfate, potassium chloride, calcium chloride, magnesium chloride or magnesium sulfate.

3. The method of claim 1, wherein the salt is sodium chloride. The emulsifier is a W / O type emulsifier, which is a Span series.

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