Silica sol and preparation method thereof

Abstract

The invention discloses silica sol and a preparation method thereof, and belongs to the technical field of silica sol preparation, the silica sol comprises sodium silicate solution, cation exchange resin, anion exchange resin, stabilizer, sodium hydroxide solution, deionized water and hydrochloric acid dilute solution, the sodium silicate solution contains SiO2 (20%) and Na2O (0.15%), the cation exchange resin is 5-10 parts, the anion exchange resin is 5-10 parts, the stabilizer is 5-10 parts, the sodium hydroxide solution is 5-10 parts, the deionized water is 5-10 parts, and the hydrochloric acid dilute solution is 5-10 parts. The sodium silicate solution is prepared from 4-9 parts of cation exchange resin and 4-9 parts of anion exchange resin, the cation exchange resin is used for removing sodium ions in the sodium silicate solution, the anion exchange resin is used for further removing anion impurities in the polysilicic acid solution, and the stabilizer is 2-5% of the mole number of SiO2. The used ion exchange resin has good regeneration performance and can be reused through the regeneration process, the production cost is reduced, and the ion exchange method does not need to use a large amount of organic solvents.

Description

Technical Field

[0001] The invention belongs to the technical field of silica sol preparation, and specifically relates to a silica sol and a preparation method thereof. Background Art

[0002] Silica sol is a dispersion system of amorphous silicon dioxide in water. It has the characteristics of good adhesion, high temperature resistance, low shrinkage, film-forming property, gelation, chargeability, energy saving, scrub resistance, corrosion resistance, non-toxicity and odorlessness.

[0003] Due to the above characteristics, silica sol is widely used in precision casting refractory materials, coating industry, papermaking industry, textile industry, and can also be used as inorganic binder, catalyst carrier, etc. Compounds such as organic silicon and trichlorosilane are common products in chemical production and are widely used in electronics, construction, transportation, chemical industry, textile, medical and other industries. Summary of the invention

[0004] (1) Technical issues to be solved

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a silica sol and a preparation method thereof, which aims to solve the technical problem that the mixture of silicon powder and other impurities reacted in production in the prior art is called waste slag. If these waste slags are directly buried, they will not only cause serious environmental pollution, but also lose a large amount of silicon, resulting in a huge waste of resources.

[0006] (2) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a silica sol, which includes a sodium silicate solution, a cation exchange resin, an anion exchange resin, a stabilizer, a sodium hydroxide solution, deionized water and a dilute hydrochloric acid solution. The sodium silicate solution contains SiO2 (20%) and Na2O (0.15%). The cation exchange resin is 5-10 parts, and the cation exchange resin removes sodium ions in the sodium silicate solution. The anion exchange resin is 4-9 parts, and the anion exchange resin further removes anionic impurities in the polysilicic acid solution. The stabilizer is 2 to 5 percent of the molar number of SiO2.

[0008] When using this technical solution, high-purity silica sol can be prepared by ion exchange method. By using cation and anion exchange resins, sodium ions and other cationic impurities and anionic impurities in water glass can be effectively removed to obtain high-purity polysilicic acid solution. The particle growth can accurately control the physicochemical properties of silica sol products such as particle size, uniformity, impurity content and stability, and silica sol with specific particle size, shape and stability can be prepared. The ion exchange method has high selectivity and can effectively separate various ions in the solution, especially for low-concentration ions, the separation effect is better: the process operation of the ion exchange method is relatively It is simple, has low equipment requirements, and is easy to realize industrial production. The ion exchange resin used has good regeneration performance and can be reused through the regeneration process, reducing production costs. The ion exchange method does not require the use of a large amount of organic solvents and is a more energy-saving preparation method. The ion exchange method produces less wastewater during the preparation process and can be recycled through proper treatment, with less impact on the environment. The ion exchange method can not only be used for the preparation of silica sol, but can also be widely used in water treatment, medicine, metallurgy, chemical industry and other fields. The silica sol prepared by the ion exchange method has a round and uniform colloidal particle shape and a dense structure, thereby improving the stability of the silica sol.

[0009] Preferably, the sodium hydroxide solution is used in an appropriate amount to adjust the pH value of the silica sol to 7-10 to maintain the stability of the silica sol, and the deionized water is used in 20 parts during the dilution and washing process to ensure the purity of the silica sol.

[0010] Furthermore, the dilute hydrochloric acid solution is 4 to 12 parts, and the dilute hydrochloric acid solution is used to regenerate the ion exchange resin and restore the exchange capacity of the silica sol.

[0011] Furthermore, the process includes ion exchange reaction, seed crystal preparation, colloid growth, evaporation concentration and silica sol purification, wherein the ion exchange reaction includes:

[0012] S1 Raw material preparation: dilute water glass (sodium silicate solution) with deionized water to 1.040-1.045 g / cm 3 ;

[0013] S2 cation exchange, adding the diluted water glass to the strong acid cation exchange resin, so that the Na+ in the water glass and the H+ in the cation exchange resin undergo ion exchange to form active polysilicic acid;

[0014] S3 anion exchange, adding the active polysilicic acid solution to anion exchange resin to remove anion impurities in the solution to obtain a high-purity polysilicic acid solution;

[0015] S4 pH adjustment: add sodium hydroxide solution or ammonia water to the polysilicic acid solution to adjust the pH to 8.5-10.5 to improve stability.

[0016] Furthermore, the seed crystal preparation is performed by aging the active silicic acid solution for 24-48 hours to form crystal nuclei.

[0017] Furthermore, the colloidal particles will grow to form a crystal nucleus silicate solution which is added to the mother liquor containing the seed crystals, and the addition rate of the silicate solution and the reaction temperature are adjusted to allow the silica sol colloidal particles to grow to the desired particle size. The reaction temperature of the silicate solution is 45 to 80 degrees, and the particle size of the silica sol colloidal particles is 10 to 20 nanometers.

[0018] Furthermore, the evaporation concentration heats the polysilicic acid solution that has completed the crystallization polymerization process and evaporates and concentrates it to obtain a polysilicic acid solution containing SiO2 (20%) and Na2O (0.15%).

[0019] Furthermore, the silica sol purification includes centrifugal separation and ion exchange. The centrifugal separation method is used to remove impurities in the silica sol to obtain a pure silica sol product. During the ion exchange, the temperature is controlled at 4-10° C. to maintain the stability of the solution.

[0020] Furthermore, the silica sol finally obtained contains SiO2 20%, Na2O 0.33%, pH 9.6, the concentration temperature is maintained at 78°C, the remaining adjustment liquid is slowly added during concentration, and the liquid level in the container is kept constant during the concentration process.

[0021] Furthermore, the evaporation rate of the silica sol is 5-6 kg / h, the heating temperature = Max. 95°C, the evaporation temperature = 45-80°C; the liquid volume is maintained at 1.2-4 l; the equipment weight is 300 kg (during operation); the equipment size is: 700×1,000×1,800 mm (W×L×H).

[0022] (3) Beneficial effects (if there are multiple beneficial effects, divide them into points and segments)

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention can prepare high-purity silica sol by ion exchange method. By using cation and anion exchange resins, sodium ions and other cationic impurities and anionic impurities in water glass can be effectively removed, thereby preparing high-purity polysilicic acid solution. The particle growth can accurately control the particle size, uniformity, impurity content and stability of silica sol products, and other physical and chemical properties, so as to prepare silica sol with specific particle size, shape and stability. The ion exchange method has high selectivity and can effectively separate various ions in the solution, especially for low-concentration ions, the separation effect is better. The process operation of the ion exchange method is relatively simple. The equipment requirements are not high and it is easy to realize industrial production. The ion exchange resin used has good regeneration performance and can be reused through the regeneration process, which reduces the production cost. The ion exchange method does not require the use of a large amount of organic solvents and is a more energy-saving preparation method. The ion exchange method produces less wastewater during the preparation process and can be recycled through proper treatment, which has little impact on the environment. The ion exchange method can not only be used for the preparation of silica sol, but can also be widely used in water treatment, medicine, metallurgy, chemical industry and other fields. The silica sol prepared by the ion exchange method has a round and uniform colloidal particle shape and a dense structure, thereby improving the stability of the silica sol. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a schematic diagram of the components of the present invention;

[0027] Figure 2 Schematic diagram of the preparation process of silica sol in the present invention;

[0028] Figure 3 It is a schematic diagram of the colloid particle growth process in the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] This specific embodiment is a silica sol and a preparation method thereof, and its structural schematic diagram is as follows Figure 1As shown, the silica sol includes sodium silicate solution, cation exchange resin, anion exchange resin, stabilizer, sodium hydroxide solution, deionized water and dilute hydrochloric acid solution. The sodium silicate solution contains SiO2 (20%), Na2O (0.15%), cation exchange resin is 5-10 parts, the cation exchange resin removes sodium ions in the sodium silicate solution, anion exchange resin is 4-9 parts, the anion exchange resin further removes anion impurities in the polysilicic acid solution, and the stabilizer is 2 to 5 percent of the molar number of SiO2.

[0031] The ion exchange method can prepare high-purity silica sol. By using cation and anion exchange resins, sodium ions and other cationic impurities in water glass, as well as anionic impurities, can be effectively removed to obtain high-purity polysilicic acid solution. The particle growth can precisely control the particle size, uniformity, impurity content and stability of the silica sol product, and can prepare silica sol with a specific particle size, shape and stability. The ion exchange method has high selectivity and can effectively separate various ions in the solution, especially for low-concentration ions, the separation effect is better: the process operation of the ion exchange method is relatively simple, and the equipment The requirements are not high and it is easy to realize industrial production. The ion exchange resin used has good regeneration performance and can be reused through the regeneration process, which reduces the production cost. The ion exchange method does not require the use of a large amount of organic solvents and is a more energy-saving preparation method. The ion exchange method generates less wastewater during the preparation process and can be recycled through proper treatment, with less impact on the environment. The ion exchange method can not only be used for the preparation of silica sol, but can also be widely used in water treatment, medicine, metallurgy, chemical industry and other fields. The silica sol prepared by the ion exchange method has a round and uniform colloidal particle shape and a dense structure, thereby improving the stability of the silica sol.

[0032] Preferably, an appropriate amount of sodium hydroxide solution is used to adjust the pH value of the silica sol to 7-10 to maintain the stability of the silica sol, and 20 parts of deionized water are used in the dilution and washing process to ensure the purity of the silica sol.

[0033] Furthermore, the dilute hydrochloric acid solution is 4 to 12 parts, and the dilute hydrochloric acid solution is used to regenerate the ion exchange resin and restore the exchange capacity of the silica sol.

[0034] Furthermore, including ion exchange reaction, crystal weight preparation, colloid growth, evaporation concentration and silica sol purification, the ion exchange reaction includes:

[0035] S1 Raw material preparation: dilute water glass (sodium silicate solution) with deionized water to 1.040-1.045 g / cm 3 ;

[0036] S2 cation exchange, adding the diluted water glass to the strong acid cation exchange resin, so that the Na+ in the water glass and the H+ in the cation exchange resin undergo ion exchange to form active polysilicic acid;

[0037] S3 anion exchange, adding the active polysilicic acid solution to anion exchange resin to remove anion impurities in the solution to obtain a high-purity polysilicic acid solution;

[0038] S4 pH adjustment: add sodium hydroxide solution or ammonia water to the polysilicic acid solution to adjust the pH to 8.5-10.5 to improve stability.

[0039] Furthermore, the seed crystal preparation is performed by aging the active silicic acid solution for 24-48 hours to form crystal nuclei.

[0040] Furthermore, the colloid growth will form a crystal nucleus silicate solution added to the mother liquor containing the seed crystal, and the addition rate of the silicate solution and the reaction temperature are adjusted to make the silica sol colloid grow to the desired particle size. The reaction temperature of the silicate solution is 45 to 80 degrees, and the particle size of the silica sol colloid is 10 to 20 nanometers.

[0041] Furthermore, the polysilicic acid solution that has completed the crystallization polymerization process is heated and evaporated to concentrate, thereby obtaining a polysilicic acid solution having a concentration of SiO2 (20%) and Na2O (1.15%).

[0042] Furthermore, the silica sol purification includes centrifugal separation and ion exchange. The impurities in the silica sol are removed by centrifugal separation to obtain a pure silica sol product. During the ion exchange, the temperature is controlled at 4-10°C to maintain the stability of the solution.

[0043] Furthermore, the silica sol finally prepared contains SiO2 20%, Na2O 0.33%, pH 9.6, the concentration temperature is maintained at 78°C, the remaining adjustment liquid is slowly added during concentration, and the liquid level in the container is kept constant during the concentration process.

[0044] Furthermore, the evaporation rate of silica sol is 5-6 kg / h, the heating temperature = Max. 95°C, the evaporation temperature = 45-80°C; the liquid volume is maintained at 1.2-4 l; the equipment weight is 300 kg (during operation); the equipment size is: 700×1,000×1,800 mm (W×L×H).

[0045] Working principle: When the device of this technical solution is used, the ion exchange method can prepare high-purity silica sol. By using cation and anion exchange resins, sodium ions and other cationic impurities and anionic impurities in water glass can be effectively removed to obtain high-purity polysilicic acid solution. The particle growth can accurately control the physicochemical properties of silica sol products such as particle size, uniformity, impurity content and stability, and can prepare silica sol with specific particle size, shape and stability; the ion exchange method has high selectivity and can effectively separate various ions in the solution, especially for low-concentration ions, the separation effect is better: the process operation of the ion exchange method The operation is relatively simple, the equipment requirements are not high, and it is easy to realize industrial production. The ion exchange resin used has good regeneration performance and can be reused through the regeneration process, reducing the production cost. The ion exchange method does not require the use of a large amount of organic solvents and is a more energy-saving preparation method. The ion exchange method produces less wastewater during the preparation process and can be recycled through proper treatment, with less impact on the environment. The ion exchange method can not only be used for the preparation of silica sol, but can also be widely used in water treatment, medicine, metallurgy, chemical industry and other fields. The silica sol prepared by the ion exchange method has a round and uniform colloidal particle shape and a dense structure, thereby improving the stability of the silica sol.

[0046] All technical features in this embodiment can be freely combined according to actual needs.

[0047] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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

1. A silica sol, characterized in that: The silica sol includes a sodium silicate solution, a cation exchange resin, an anion exchange resin, a stabilizer, a sodium hydroxide solution, deionized water and a dilute hydrochloric acid solution. The sodium silicate solution contains SiO2 (20%) and Na2O (1.15%). The cation exchange resin is 5-10 parts, and the cation exchange resin removes sodium ions in the sodium silicate solution. The anion exchange resin is 4-9 parts, and the anion exchange resin further removes anionic impurities in the polysilicic acid solution. The stabilizer is 2 to 5 percent of the molar number of SiO2.

2. A silica sol according to claim 1, characterized in that: The sodium hydroxide solution is used in an appropriate amount to adjust the pH value of the silica sol to 7-10 to maintain the stability of the silica sol, and the deionized water is used in 20 parts during the dilution and washing process to ensure the purity of the silica sol.

3. A silica sol according to claim 1, characterized in that: The dilute hydrochloric acid solution is 4 to 12 parts and is used for regenerating the ion exchange resin and restoring the exchange capacity of the silica sol.

4. A method for preparing silica sol, used for preparing the silica sol according to claim 1, characterized in that: The method comprises ion exchange reaction, seed crystal preparation, colloid particle growth, evaporation concentration and silica sol purification. The ion exchange reaction comprises: S1 Raw material preparation: dilute water glass (sodium silicate solution) with deionized water to 1.040-1.045 g / cm 3 ; S2 cation exchange, adding the diluted water glass to the strong acid cation exchange resin, so that the Na+ in the water glass and the H+ in the cation exchange resin undergo ion exchange to form active polysilicic acid; S3 anion exchange, adding the active polysilicic acid solution to anion exchange resin to remove anion impurities in the solution to obtain a high-purity polysilicic acid solution; S4 pH adjustment: add sodium hydroxide solution or ammonia water to the polysilicic acid solution to adjust the pH to 8.5-10.5 to improve stability.

5. The method for preparing silica sol according to claim 4, characterized in that: The seed crystal preparation comprises aging the active silicic acid solution for 24-48 hours to form crystal nuclei.

6. A method for preparing silica sol according to claim 4, characterized in that: The colloidal particles will grow by adding a crystal nucleus silicate solution into a mother liquor containing crystal seeds, and the addition rate of the silicate solution and the reaction temperature are adjusted to allow the silica sol colloidal particles to grow to the desired particle size. The reaction temperature of the silicate solution is 45 to 80 degrees, and the particle size of the silica sol colloidal particles is 10 to 20 nanometers.

7. The method for preparing silica sol according to claim 4, characterized in that: The evaporation and concentration heats the polysilicic acid solution that has completed the crystallization polymerization process and evaporates and concentrates it to obtain a polysilicic acid solution containing SiO2 (20%) and Na2O (0.15%).

8. The method for preparing silica sol according to claim 4, characterized in that: The silica sol purification includes centrifugal separation and ion exchange. The centrifugal separation method is used to remove impurities in the silica sol to obtain a pure silica sol product. During the ion exchange, the temperature is controlled at 4-10° C. to maintain the stability of the solution.

9. The method for preparing silica sol according to claim 4, characterized in that: The silica sol finally obtained contains SiO2 20%, Na2O 0.33%, and pH 9.

6. The concentration temperature is maintained at 78°C. The remaining adjustment liquid is slowly added during concentration, and the liquid level in the container is kept constant during the concentration process.

10. The method for preparing silica sol according to claim 4, characterized in that: The evaporation rate of the silica sol is 5-6 kg / h, the heating temperature is Max. 95°C, the evaporation temperature is 45-80°C; the liquid volume is maintained at 1.2-4 l; the equipment weight is 300 kg (during operation); the equipment size is 700×1,000×1,800 mm (W×L×H).

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