Continuous recovery method of solvent in silicon microsphere production

Abstract

The invention relates to a continuous recovery method of a solvent in silicon microsphere production, and belongs to the technical field of silicon microsphere production. After the silicon microspheres are prepared, the filtrate is collected, the modified adsorbent is added for ultrasonic treatment, and then the semi-permeable membrane is used for separation, so that efficient recovery of the solvent is realized. In the general production process of silicon microspheres, a solvent can become steam to be volatilized in the drying step, so that the environment is polluted. The method not only can reduce the waste of the solvent, but also can reduce the production cost; through continuous recovery of the solvent, emission of harmful gas is remarkably reduced, and the method has important significance on environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon microsphere production, and relates to a continuous recovery method of a solvent in silicon microsphere production. Background Art

[0002] As an important material, silicon microspheres are widely used in many fields such as electronics, medicine, and coatings. In the production process of silicon microspheres, the use of solvents is essential, but this also brings about the problems of solvent consumption and environmental pollution. In the production process of silicon microspheres, the solvent will turn into steam and evaporate during the drying step, and this part of the solvent is often not effectively recovered and utilized, which not only causes a waste of resources, but also increases the burden on the environment.

[0003] In order to achieve effective recovery of solvents, reduce pollution to the environment, and improve resource utilization, people have begun to explore continuous recovery methods for solvents in silicon microsphere production. Existing solvent recovery methods often have problems such as low recovery efficiency, complex operation, and high cost, which limits their wide application in silicon microsphere production. Therefore, there is an urgent need to develop an efficient and simple recovery method to meet the demand for solvent recovery in silicon microsphere production. It is based on this background that the present invention proposes a novel continuous solvent recovery method, in order to solve the problems existing in the prior art and achieve efficient recovery of solvents in silicon microsphere production. Summary of the invention

[0004] The purpose of the present invention is to provide a method for continuously recovering solvent in the production of silicon microspheres, which has the characteristics of high recovery efficiency.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for continuous recovery of solvent in silicon microsphere production, the specific process of the method is as follows:

[0007] S1: Anhydrous ethanol and aqueous ammonia are mixed in a volume ratio of 1:(0.5-2), stirred at a speed of 150 r / min for 0.5 h, heated to 30-35° C. while stirring, and continued to stir for 0.5 h after constant temperature to obtain a mixed solution A;

[0008] S2: tetraethyl silicate and methyltriethylsilane are mixed in a volume ratio of (1-3):1 to obtain a mixed solution B;

[0009] S3: Add dimethyl sulfoxide dropwise to the mixed solution B at a volume ratio of 1:1, and stir at a speed of 200 r / min for 0.5 to 1 h to obtain a mixed solution C;

[0010] S4: Under constant temperature, the stirring rate of the mixed solution A is increased to 400 r / min, and the mixed solution C is added dropwise to the mixed solution A, the volume ratio of the mixed solution A to the mixed solution C is 1:1, and after the addition is completed, the temperature is slowly raised to 50°C, and then 3-4 wt% of ethanolamine is added, and the mixture is stirred at a constant temperature for 2-3 hours. After the reaction is completed, it is filtered and dried with hot air to obtain silicon microspheres;

[0011] S5: collecting the filtrate obtained after filtration, adding a modified adsorbent to the filtrate, ultrasonicating for 2 to 3 hours, and then separating with a semipermeable membrane to complete the recovery process;

[0012] The preparation method of the modified adsorbent is as follows:

[0013] S5.1: Activated carbon and vermiculite were mixed in a mass ratio of 2:1, and ground in a ball mill at a speed of 400 r / min for 1 h to obtain a mixture D. The mixture D was placed in a 10% hydrochloric acid solution, heated to 80°C, condensed and refluxed for 40 min, filtered, and washed with deionized water until the pH value of the surface of the mixture D was 7;

[0014] S5.2: dissolving graphene oxide in an acetone solution to obtain a mixed solution with a mass fraction of graphene oxide of 30%, dispersing mixture D in the mixed solution, with a mass ratio of mixture D to graphene oxide of 1:1, adding 3wt% silane coupling agent, and ultrasonicating for 1h to obtain a solid-liquid mixture E;

[0015] S5.3: The solid-liquid mixture E is placed in liquid nitrogen and frozen for 15 to 20 minutes, and then dried at -70 to -50°C in a vacuum state for 4 to 6 hours, and the dried solid is ground to obtain the modified adsorbent.

[0016] Furthermore, the concentration of the ammonia water in S1 is 1 mol / L.

[0017] Furthermore, the rate of adding dimethyl sulfoxide in S3 is 3s / drop.

[0018] Furthermore, the dropping rate of the mixed solution C in S4 is 1 s / drop.

[0019] Furthermore, the rate of slowly heating in S4 is 2°C / min.

[0020] Furthermore, the parameters of hot air drying in S4 are a drying temperature of 50 to 80° C. and a drying time of 15 to 20 minutes.

[0021] Furthermore, the semipermeable membrane in S5 is a polyethersulfone membrane with a pore size of 0.22 μm.

[0022] Furthermore, the concentration of the acetone solution in S5.2 is 3 mol / L.

[0023] Furthermore, the silane coupling agent in S5.2 is one of silane coupling agent KH-560 and silane coupling agent KH-792.

[0024] Furthermore, the particle size of the modified adsorbent obtained by grinding in S5.3 is 200 mesh.

[0025] After preparing silicon microspheres, the present invention collects the filtrate and adds a modified adsorbent for ultrasonic treatment, and then uses a semipermeable membrane for separation, thereby achieving efficient recovery of the solvent. The method of the present invention can not only reduce the waste of solvent, but also reduce production costs; in the traditional silicon microsphere production process, the solvent will become steam and evaporate in the drying step, causing pollution to the environment. The method of the present invention significantly reduces the emission of harmful gases through the continuous recovery of the solvent, which is of great significance to environmental protection.

[0026] Anhydrous ethanol and ammonia water provide the alkaline environment and solvent required for the reaction. Anhydrous ethanol as a solvent helps the uniform mixing and reaction of the reactants; ammonia water is used to adjust the pH value of the solution and promote the hydrolysis reaction of tetraethyl silicate. As components of mixed solution B, tetraethyl silicate and methyltriethylsilane are the main raw materials of silica microspheres. They generate siloxane skeletons in hydrolysis and condensation reactions, forming the basic structure of silica microspheres. Dimethyl sulfoxide is used as a solvent and reaction medium. Dimethyl sulfoxide helps the uniform mixing and reaction of the components in mixed solution B. At the same time, it may also participate in the formation process of silica microspheres and affect the morphology and properties of silica microspheres. The addition of ethanolamine can further promote the hydrolysis and condensation reactions of tetraethyl silicate and methyltriethylsilane, which helps the stability and growth of silica microspheres. At the same time, ethanolamine may also act as a surfactant to improve the dispersibility and surface properties of silica microspheres.

[0027] In the solvent recovery step, the modified adsorbent is used to adsorb and remove impurities and harmful substances in the filtrate, and then through ultrasonic treatment and semipermeable membrane separation, the solvent can be efficiently recovered and reused. The solvent recovered in the present invention is dimethyl sulfoxide, anhydrous ethanol and ammonia water.

[0028] The modified adsorbent used in the present invention has higher adsorption capacity and can more effectively adsorb the solvent components in the filtrate, thereby improving the recovery efficiency of the solvent.

[0029] Activated carbon has a large specific surface area and rich pore structure, and can adsorb a large amount of solvents and impurities. Vermiculite has good swelling and adsorption properties, and can increase the porosity and adsorption capacity of the adsorbent. When mixed with activated carbon, it can form a complementary effect and improve the overall performance of the adsorbent. Through acid treatment, impurities on the surface of activated carbon and vermiculite can be removed, and their purity and adsorption performance can be improved. The introduction of graphene oxide also increases the surface area and active sites of the adsorbent, improves its adsorption performance, and further enhances its adsorption performance. Silane coupling agent can enhance the binding force between activated carbon and graphene oxide, making the structure of the modified adsorbent more stable and not easy to fall off or fail. Silane coupling agent can also improve the wettability and dispersibility of the adsorbent surface, and increase its contact area with the filtrate and adsorption efficiency.

[0030] The modified adsorbent can not only adsorb the solvent, but also effectively remove impurities and harmful substances in the filtrate, such as residual reactants, by-products, etc., thereby improving the quality of the filtrate. In the present invention, residual organic matter such as incompletely reacted tetraethyl silicate, methyltriethylsilane, dimethyl sulfoxide, etc. can be effectively removed.

[0031] Beneficial effects of the present invention:

[0032] (1) The modified adsorbent used in the present invention can not only adsorb the solvent, but also effectively remove impurities, residual reactants and other harmful substances in the filtrate, thereby improving the quality of the filtrate. The mixed use of activated carbon and vermiculite and the introduction of graphene oxide increase the adsorption capacity and adsorption rate of the adsorbent, thereby improving the purification effect of the filtrate.

[0033] (2) After preparing silicon microspheres, the present invention collects the filtrate and adds a modified adsorbent for ultrasonic treatment, and then uses a semipermeable membrane for separation, thereby achieving efficient recovery of the solvent. The method of the present invention can not only reduce the waste of solvent, but also reduce production costs; generally, in the production process of silicon microspheres, the solvent will become steam and evaporate in the drying step, causing pollution to the environment. The present invention significantly reduces the emission of harmful gases through continuous recovery of solvents, which is of great significance to environmental protection. DETAILED DESCRIPTION

[0034] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0035] Example 1

[0036] A method for continuous recovery of solvent in silicon microsphere production, the specific process of the method is as follows:

[0037] S1: Anhydrous ethanol and 1 mol / L ammonia water were mixed in a volume ratio of 1:1, stirred at a speed of 150 r / min for 0.5 h, heated to 30°C while stirring, and continued stirring for 0.5 h after constant temperature to obtain a mixed solution A;

[0038] S2: tetraethyl silicate and methyltriethylsilane are mixed in a volume ratio of 2:1 to obtain a mixed solution B;

[0039] S3: dimethyl sulfoxide was added dropwise to the mixed solution B at a rate of 3 s / drop and a volume ratio of 1:1. The mixture was stirred at a speed of 200 r / min for 0.5 h to obtain a mixed solution C.

[0040] S4: Under constant temperature, the stirring rate of mixed solution A is increased to 400r / min, and mixed solution C is added to mixed solution A at a rate of 1s / drop, the volume ratio of mixed solution A to mixed solution C is 1:1, and after the addition is completed, the temperature is slowly raised to 50°C at a rate of 2°C / min, and then 3wt% of ethanolamine is added, and the mixture is stirred at a constant temperature for 3h. After the reaction is completed, it is filtered and dried with hot air. The parameters of hot air drying are drying temperature 80°C and drying time 15min to obtain silicon microspheres;

[0041] S5: Collect the filtrate obtained after filtration, add the modified adsorbent to the filtrate, the solid-liquid mass ratio is 1:1, ultrasonicate for 2 hours, and then separate using a semipermeable membrane, the semipermeable membrane is a polyethersulfone membrane with a pore size of 0.22 μm, to complete the recovery process;

[0042] The preparation method of the modified adsorbent is as follows:

[0043] S5.1: Activated carbon and vermiculite were mixed in a mass ratio of 2:1, and ground in a ball mill at a speed of 400 r / min for 1 h to obtain a mixture D. The mixture D was placed in a 10% hydrochloric acid solution with a solid-liquid mass ratio of 1:2, heated to 80°C, condensed and refluxed for 40 min, filtered, and washed with deionized water until the surface pH value of the mixture D was 7;

[0044] S5.2: dissolving graphene oxide in an acetone solution having a concentration of 3 mol / L to obtain a mixed solution having a mass fraction of graphene oxide of 30%, dispersing mixture D in the mixed solution, wherein the mass ratio of mixture D to graphene oxide is 1:1, adding 3 wt % of silane coupling agent KH-560, and ultrasonicating for 1 h to obtain a solid-liquid mixture E;

[0045] S5.3: The solid-liquid mixture E is placed in liquid nitrogen and frozen for 15 minutes, and then dried at -70°C in a vacuum state for 4 hours. The dried solid is ground to obtain the modified adsorbent. The particle size of the ground modified adsorbent is 200 mesh.

[0046] Example 2

[0047] A method for continuous recovery of solvent in silicon microsphere production, the specific process of the method is as follows:

[0048] S1: Anhydrous ethanol and 1 mol / L ammonia water were mixed in a volume ratio of 1:0.5, stirred at a speed of 150 r / min for 0.5 h, heated to 35°C while stirring, and continued stirring for 0.5 h after constant temperature to obtain a mixed solution A;

[0049] S2: tetraethyl silicate and methyltriethylsilane are mixed in a volume ratio of 1:1 to obtain a mixed solution B;

[0050] S3: dimethyl sulfoxide was added dropwise to the mixed solution B at a rate of 3 s / drop and a volume ratio of 1:1. The mixture was stirred at a speed of 200 r / min for 1 h to obtain a mixed solution C.

[0051] S4: Under constant temperature, the stirring rate of the mixed solution A is increased to 400r / min, and the mixed solution C is added to the mixed solution A at a rate of 1s / drop, the volume ratio of the mixed solution A to the mixed solution C is 1:1, and after the addition is completed, the temperature is slowly raised to 50°C at a rate of 2°C / min, and then 4wt% of ethanolamine is added, and the mixture is stirred at a constant temperature for 2h. After the reaction is completed, it is filtered and dried with hot air. The parameters of the hot air drying are a drying temperature of 50°C and a drying time of 20min to obtain silicon microspheres;

[0052] S5: Collect the filtrate obtained after filtration, add the modified adsorbent to the filtrate, the solid-liquid mass ratio is 1:1, ultrasonicate for 3 hours, and then separate using a semipermeable membrane, the semipermeable membrane is a polyethersulfone membrane with a pore size of 0.22 μm, to complete the recovery process;

[0053] The preparation method of the modified adsorbent is as follows:

[0054] S5.1: Activated carbon and vermiculite were mixed in a mass ratio of 2:1, and ground in a ball mill at a speed of 400 r / min for 1 h to obtain a mixture D. The mixture D was placed in a 10% hydrochloric acid solution with a solid-liquid mass ratio of 1:2, heated to 80°C, condensed and refluxed for 40 min, filtered, and washed with deionized water until the surface pH value of the mixture D was 7;

[0055] S5.2: dissolving graphene oxide in an acetone solution with a concentration of 3 mol / L to obtain a mixed solution with a mass fraction of graphene oxide of 30%, dispersing mixture D in the mixed solution, with a mass ratio of mixture D to graphene oxide of 1:1, adding 3 wt % of silane coupling agent KH-792, and ultrasonicating for 1 h to obtain a solid-liquid mixture E;

[0056] S5.3: The solid-liquid mixture E is placed in liquid nitrogen and frozen for 20 minutes, and then dried at -50°C in a vacuum state for 6 hours. The dried solid is ground to obtain the modified adsorbent. The particle size of the ground modified adsorbent is 200 mesh.

[0057] Example 3

[0058] A method for continuous recovery of solvent in silicon microsphere production, the specific process of the method is as follows:

[0059] S1: Anhydrous ethanol and 1 mol / L ammonia water were mixed in a volume ratio of 1:2, stirred at a speed of 150 r / min for 0.5 h, heated to 30°C while stirring, and continued stirring for 0.5 h after constant temperature to obtain a mixed solution A;

[0060] S2: tetraethyl silicate and methyltriethylsilane are mixed in a volume ratio of 3:1 to obtain a mixed solution B;

[0061] S3: dimethyl sulfoxide was added dropwise to the mixed solution B at a rate of 3 s / drop and a volume ratio of 1:1. The mixture was stirred at a speed of 200 r / min for 1 h to obtain a mixed solution C.

[0062] S4: Under constant temperature, the stirring rate of mixed solution A is increased to 400r / min, and mixed solution C is added to mixed solution A at a rate of 1s / drop, the volume ratio of mixed solution A to mixed solution C is 1:1, and after the addition is completed, the temperature is slowly raised to 50°C at a rate of 2°C / min, and then 3wt% of ethanolamine is added, and the mixture is stirred at a constant temperature for 3h. After the reaction is completed, it is filtered and dried with hot air. The parameters of hot air drying are drying temperature 80°C and drying time 15min to obtain silicon microspheres;

[0063] S5: Collect the filtrate obtained after filtration, add the modified adsorbent to the filtrate, the solid-liquid mass ratio is 1:1, ultrasonicate for 2 hours, and then separate using a semipermeable membrane, the semipermeable membrane is a polyethersulfone membrane with a pore size of 0.22 μm, to complete the recovery process;

[0064] The preparation method of the modified adsorbent is as follows:

[0065] S5.1: Activated carbon and vermiculite were mixed in a mass ratio of 2:1, and ground in a ball mill at a speed of 400 r / min for 1 h to obtain a mixture D. The mixture D was placed in a 10% hydrochloric acid solution with a solid-liquid mass ratio of 1:2, heated to 80°C, condensed and refluxed for 40 min, filtered, and washed with deionized water until the surface pH value of the mixture D was 7;

[0066] S5.2: dissolving graphene oxide in an acetone solution having a concentration of 3 mol / L to obtain a mixed solution having a mass fraction of graphene oxide of 30%, dispersing mixture D in the mixed solution, wherein the mass ratio of mixture D to graphene oxide is 1:1, adding 3 wt % of silane coupling agent KH-560, and ultrasonicating for 1 h to obtain a solid-liquid mixture E;

[0067] S5.3: The solid-liquid mixture E is placed in liquid nitrogen and frozen for 20 minutes, and then dried at -70°C in a vacuum state for 4 hours. The dried solid is ground to obtain the modified adsorbent. The particle size of the ground modified adsorbent is 200 mesh.

[0068] Comparative Example 1

[0069] In this comparative example, no acid treatment was performed during the adsorbent modification process, and the remaining steps were consistent with those in Example 1.

[0070] Comparative Example 2

[0071] In this comparative example, no vermiculite was added during the adsorbent modification process, and the remaining steps were consistent with those of Example 1.

[0072] Comparative Example 3

[0073] In this comparative example, graphene oxide is not introduced during the adsorbent modification process, and the remaining steps are consistent with Example 1.

[0074] Comparative Example 4

[0075] In this comparative example, no silane coupling agent is added during the adsorbent modification process, and the remaining steps are consistent with Example 1.

[0076] The solvent recovery efficiency, metal ion removal rate and organic matter removal rate in Examples 1 to 3 and Comparative Examples 1 to 4 were tested.

[0077] Solvent recovery efficiency (%) = (residual solvent before adding modified adsorbent - residual solvent after adding modified adsorbent) / residual solvent before adding modified adsorbent × 100%;

[0078] Metal ion removal rate (%) = (metal ion content before treatment - metal ion content after treatment) / metal ion content before treatment × 100%;

[0079] Organic matter removal rate (%) = (organic matter content before treatment - organic matter content after treatment) / organic matter content before treatment × 100%;

[0080] The experimental results are summarized in the following table:

[0081] Solvent recovery efficiency (%) Metal ion removal rate (%) Organic matter removal rate (%) Example 1 96 95 99 Example 2 95 94 98 Example 3 95 95 98 Comparative Example 1 90 89 89 Comparative Example 2 85 80 83 Comparative Example 3 89 86 87 Comparative Example 4 88 88 87

[0082] Experimental data show that modification of the adsorbent effectively improves the solvent recovery efficiency, metal ion removal rate and organic matter removal rate.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for continuous recovery of solvent in silicon microsphere production, characterized in that: The specific process of the method is as follows: S1: Anhydrous ethanol and aqueous ammonia are mixed in a volume ratio of 1:(0.5-2), stirred at a speed of 150 r / min for 0.5 h, heated to 30-35° C. while stirring, and continued to stir for 0.5 h after constant temperature to obtain a mixed solution A; S2: tetraethyl silicate and methyltriethylsilane are mixed in a volume ratio of (1-3):1 to obtain a mixed solution B; S3: Add dimethyl sulfoxide dropwise to the mixed solution B at a volume ratio of 1:1, and stir at a speed of 200 r / min for 0.5 to 1 h to obtain a mixed solution C; S4: Under constant temperature, the stirring rate of the mixed solution A is increased to 400 r / min, and the mixed solution C is added dropwise to the mixed solution A, the volume ratio of the mixed solution A to the mixed solution C is 1:1, and after the addition is completed, the temperature is slowly raised to 50°C, and then 3-4 wt% of ethanolamine is added, and the mixture is stirred at a constant temperature for 2-3 hours. After the reaction is completed, it is filtered and dried with hot air to obtain silicon microspheres; S5: collecting the filtrate obtained after filtration, adding a modified adsorbent to the filtrate, ultrasonicating for 2 to 3 hours, and then separating with a semipermeable membrane to complete the recovery process; The preparation method of the modified adsorbent is as follows: S5.1: Activated carbon and vermiculite were mixed in a mass ratio of 2:1, and ground in a ball mill at a speed of 400 r / min for 1 h to obtain a mixture D. The mixture D was placed in a 10% hydrochloric acid solution, heated to 80°C, condensed and refluxed for 40 min, filtered, and washed with deionized water until the pH value of the surface of the mixture D was 7; S5.2: dissolving graphene oxide in an acetone solution to obtain a mixed solution with a mass fraction of graphene oxide of 30%, dispersing mixture D in the mixed solution, with a mass ratio of mixture D to graphene oxide of 1:1, adding 3wt% silane coupling agent, and ultrasonicating for 1h to obtain a solid-liquid mixture E; S5.3: The solid-liquid mixture E is placed in liquid nitrogen and frozen for 15 to 20 minutes, and then dried at -70 to -50°C in a vacuum state for 4 to 6 hours, and the dried solid is ground to obtain the modified adsorbent.

2. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The concentration of the ammonia water in the S1 is 1 mol / L.

3. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The rate of adding dimethyl sulfoxide in S3 is 3s / drop.

4. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The dropping rate of the mixed solution C in S4 is 1 s / drop.

5. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The rate of slow heating in S4 is 2°C / min.

6. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The parameters of hot air drying in S4 are a drying temperature of 50 to 80° C. and a drying time of 15 to 20 minutes.

7. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The semipermeable membrane in S5 is a polyethersulfone membrane with a pore size of 0.22 μm.

8. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The concentration of the acetone solution in S5.2 is 3 mol / L.

9. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The silane coupling agent in S5.2 is one of silane coupling agent KH-560 and silane coupling agent KH-792.

10. The method for continuous recovery of solvent in silicon microsphere production according to claim 1, characterized in that: The particle size of the modified adsorbent obtained by grinding in S5.3 is 200 mesh.