Method for preparing sodium silicate using rice husk

Abstract

The invention provides a method for preparing sodium silicate by using rice husks, and belongs to the technical field of sodium silicate. The method comprises pretreatment, roasting and synthesis reaction steps. The synthesis reaction step comprises adding rice husk ash and sodium hydroxide solution into a reaction container, then adding hyaluronic acid and glucomannan, stirring evenly, raising the temperature to 118-123°C at a rate of 3.8-4.2°C / min, and performing stepwise reaction. After the reaction is completed, the temperature is naturally lowered to room temperature, and a sodium silicate solution is prepared through precipitation, stratification and vacuum filtration. The sodium silicate prepared by the method has high SiO2 dissolution rate, high metal impurity leaching rate and stable modulus.

Description

Technical Field

[0001] The invention belongs to the technical field of sodium silicate, and particularly relates to a method for preparing sodium silicate by utilizing rice husks. Background Art

[0002] Sodium silicate, commonly known as sodium silicate, its aqueous solution is commonly known as water glass, and its chemical formula is Na2O·nSiO2. It is a soluble inorganic silicate and is widely used in papermaking, machinery, electronics, chemicals, construction materials, food, oil fields, mining, ceramics and other fields. As an important raw material for synthesizing silicon dioxide, the performance of sodium silicate is directly related to the performance and use effect of silicon dioxide.

[0003] China is a major producer and consumer of rice. Rice husk, as the main by-product of rice processing and dehulling, can account for about 23% of the mass of rice itself. Rice husk has a large output and is a renewable resource. However, rice husk has long been regarded as agricultural waste. Currently, the main way to deal with rice husk is landfill or incineration, which brings about problems of resource waste and environmental pollution.

[0004] Rice husk has a three-dimensional network structure composed of silica and organic matter, including approximately 20wt% SiO2 and 80wt% cellulose. Compared with other biomass such as corn cobs, bamboo leaves, and straw, rice husk has a higher silica content; therefore, rice husk has the huge advantages of being cheap and abundant in yield.

[0005] As people's research on the utilization of rice husks continues to deepen, the siliceous components in rice husks or rice husk ash can be used as a silicon source to prepare silicon-containing compounds such as sodium silicate, white carbon black, and silica gel. They can also be used as silicon fertilizer in agricultural production, which is conducive to solving the problems of high cost and difficult production process in traditional preparation technology.

[0006] The sodium silicate produced from rice husks in the prior art has defects such as unstable modulus, many impurities, and low silicon content, which leads to unstable and poor quality of silicon dioxide and affected dispersibility, which in turn affects its use effect and cannot meet the use needs in high-end fields, making silicon dioxide mainly rely on imports in high-end application fields.

[0007] Therefore, the method of preparing high-quality sodium silicate using rice husk needs to be studied and promoted urgently. Summary of the invention

[0008] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing sodium silicate by using rice husk. The sodium silicate has high whiteness, stable modulus and high SiO2 dissolution rate.

[0009] In view of the above technical problems, the present invention adopts the following technical solutions:

[0010] The method for preparing sodium silicate using rice husk comprises the following steps:

[0011] 1. Preprocessing

[0012] The rice husk is placed in deionized water for cleaning, filtered and dried, and then a pretreatment agent and a chaotropic agent are added for ultrasonic soaking treatment. The ultrasonic soaking time is 3.3-3.8 hours, the ultrasonic power is 380-420W, the ultrasonic frequency is 27-33kHz, and the temperature is 68-72°C. After the soaking, the rice husk is centrifuged and filtered at a speed of 3800-4300rpm for 23-27 minutes. After washing, the rice husk is dried at 95-105°C for 1.8-2.3 hours to obtain a prefabricated rice husk.

[0013] The pretreatment agent is a 9.6-10.4wt% citric acid solution;

[0014] The mass volume ratio of the rice husk, deionized water, pretreatment agent and dissolution promoter is 58-62g:320-330g:1760-1800mL:5.8-6.3g;

[0015] The dissolving agent is a mixture of sodium thioglycolate and a primary dissolving agent, and the mass ratio of the sodium thioglycolate to the primary dissolving agent is 0.8-1.2:0.4;

[0016] The preparation method of the primary solubilizing agent is as follows: diethylenetriamine and propylene glycol are mixed, the temperature is raised to 60-64° C., and the mixture is stirred evenly to obtain an aminating agent; a 30wt% ethanol solution is introduced into a closed container, citric acid is added, and the mixture is stirred evenly, and then the aminating agent is added at a rate of 1.2-1.4 mL / min, and the mixture is stirred at a speed of 335-345 rpm. After the addition is completed, the mixture is heated to 82-86° C. at a rate of 1.8-2.2° C. / min, and the mixture is refluxed for reaction for 18-22 hours. After the reaction is completed, the mixture is cooled, filtered, washed, and dried to obtain the primary solubilizing agent;

[0017] The mass ratio of diethylenetriamine to glycerol is 5.5-5.8:1.4-1.6;

[0018] The mass volume ratio of the ethanol solution, citric acid and aminating agent is 18-22 mL: 6.5-6.7 g: 3.2-3.6 g.

[0019] 2. Roasting

[0020] The prefabricated rice husk is heated to 450-470°C at a rate of 12-15°C / min, roasted at 450-470°C for 20-30min, then heated to 695-705°C at a rate of 10-14°C / min, roasted at 695-705°C for 2.3-2.7h, taken out after roasting, ground to a particle size of 70-90 mesh, and obtained rice husk ash.

[0021] 3. Synthesis reaction

[0022] Add rice husk ash and sodium hydroxide solution to a reaction container, then add hyaluronic acid and glucomannan, stir evenly, raise the temperature to 118-123° C. at a rate of 3.8-4.2° C. / min, perform step-by-step reaction at 118-123° C., the pressure is 0.63-0.67 MPa, the reaction time is 2.4-2.6 h, and after the reaction is completed, naturally cool to room temperature, perform precipitation and stratification, and vacuum filtration to obtain a sodium silicate solution;

[0023] The concentration of the sodium hydroxide solution is 1.4-1.6 mol / L;

[0024] The mass volume ratio of the rice husk ash, sodium hydroxide solution, hyaluronic acid and glucomannan is 95-105 g: 3400-3600 mL: 0.46-0.50 g: 0.52-0.56 g;

[0025] In the stepwise reaction, the stirring speed is controlled at 270-300 rpm in the first 20 min of the reaction, at 330-350 rpm in the last 20 min of the reaction, and at 780-820 rpm for the rest of the time.

[0026] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0027] 1. The present invention uses rice husk as a raw material to prepare sodium silicate, and performs pretreatment by using a pretreatment agent and a dissolution promoter. As the pretreatment proceeds, the leaching rate of metal impurities will continue to decrease. After the dissolution promoter is added, the primary dissolution promoter and sodium thioglycolate cooperate to be adsorbed on the surface of the rice husk by means of hydrogen bonding, thereby reducing interfacial tension, enhancing contact and diffusion with the pretreatment agent, promoting the reaction between the metal impurities and the pretreatment agent, improving the leaching rate and leaching effect of the metal impurities, and thereby improving the specific surface area and micropore volume of the rice husk ash, further improving the whiteness and activity of the rice husk ash and the purity of silicon dioxide, wherein the primary dissolution promoter is a propylene glycol-diethyl ether solution. The alkene triamine is dispersed, and the amino group on it reacts with the carboxyl group of citric acid for acylation reaction. The obtained primary dissolving agent has more hydroxyl, carboxyl and amino groups, and has good stability. It can efficiently and stably form hydrogen bonds with rice husks, and effectively promote the pretreatment step. In the synthesis reaction step, hyaluronic acid and glucomannan are added, which can be adsorbed on the surface of sodium silicate, can prevent the mutual aggregation and collision between sodium silicates, thereby avoiding its agglomeration and sedimentation. Combined with the step-by-step stirring dissolution-promoting method, the dispersibility of the reaction raw materials and reaction products in the reaction solution is further improved, so that the synthesis reaction is more complete, which is conducive to obtaining a sodium silicate product with higher quality.

[0028] 2. The sodium silicate solution is prepared by the method of the present invention, and the whiteness of the rice husk ash is 92.4-92.9%;

[0029] 3. The method of the present invention is used to prepare sodium silicate solution, and the K leaching rate is 89.04-89.92%, the Na leaching rate is 33.98-34.34%, and the Ca leaching rate is 55.12-55.96%;

[0030] 4. The method of the present invention is used to prepare a sodium silicate solution with a modulus of 2.89-2.94 and a silicon dioxide dissolution rate of 98.7-99.5%. DETAILED DESCRIPTION

[0031] In order to more clearly understand the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described.

[0032] Example 1

[0033] 1. Preprocessing

[0034] 60 g of rice husk was placed in 325 g of deionized water for cleaning, filtered and dried, and then 1780 mL of pretreatment agent and 6.0 g of chaotropic agent were added for ultrasonic soaking treatment. The ultrasonic soaking time was 3.5 h, the ultrasonic power was 400 W, the ultrasonic frequency was 30 kHz, and the temperature was 70 ° C. After the soaking, the rice husk was centrifuged at a speed of 4000 rpm for 25 min. After washing, the rice husk was dried at 100 ° C for 2 h to obtain prefabricated rice husk;

[0035] The pretreatment agent is a 10wt% citric acid solution;

[0036] The dissolving agent is a mixture of sodium thioglycolate and a primary dissolving agent, and the mass ratio of the sodium thioglycolate to the primary dissolving agent is 1:0.4;

[0037] The preparation method of the primary dissolving agent is as follows: 5.7g of diethylenetriamine and 1.5g of propylene glycol are mixed, the temperature is raised to 62°C and stirred, and after stirring evenly, an aminating agent is prepared; 20mL of 30wt% ethanol solution is introduced into a closed container, 6.6g of citric acid is added, and after stirring evenly, 3.4g of the aminating agent is added at a rate of 1.3mL / min, and stirring is performed while adding, and the stirring speed is 340rpm. After the addition is completed, the temperature is raised to 84°C at a rate of 2.0°C / min, and reflux reaction is carried out for 20h. After the reaction is completed, the primary dissolving agent is prepared by cooling, filtering, washing, and drying.

[0038] 2. Roasting

[0039] The prefabricated rice husk was heated to 460°C at a rate of 14°C / min, roasted at 460°C for 25 minutes, then heated to 700°C at a rate of 12°C / min, roasted at 700°C for 2.5 hours, taken out after roasting, ground to a particle size of 80 mesh, and obtained rice husk ash.

[0040] 3. Synthesis reaction

[0041] Add 100 g of rice husk ash and 3500 mL of sodium hydroxide solution to a reaction container, then add 0.48 g of hyaluronic acid and 0.54 g of glucomannan, stir evenly, raise the temperature to 120° C. at a rate of 4.0° C. / min, perform step-by-step reaction at 120° C., the pressure is 0.65 MPa, the reaction time is 2.5 h, and after the reaction is completed, naturally cool to room temperature, and obtain a sodium silicate solution through precipitation, stratification, and vacuum filtration;

[0042] The concentration of the sodium hydroxide solution is 1.5 mol / L;

[0043] In the stepwise reaction, the stirring speed was controlled at 280 rpm in the first 20 min of the reaction, at 340 rpm in the last 20 min of the reaction, and at 800 rpm for the rest of the time.

[0044] Example 2

[0045] 1. Preprocessing

[0046] 58 g of rice husk was placed in 320 g of deionized water for cleaning, filtered and dried, and then 1760 mL of pretreatment agent and 5.8 g of chaotropic agent were added for ultrasonic soaking treatment. The ultrasonic soaking time was 3.3 h, the ultrasonic power was 380 W, the ultrasonic frequency was 27 kHz, and the temperature was 68 ° C. After the soaking, the rice husk was centrifuged and filtered at a speed of 3800 rpm for 23 min. After washing, the rice husk was dried at 95 ° C for 2.3 h to obtain prefabricated rice husk;

[0047] The pretreatment agent is a 9.6wt% citric acid solution;

[0048] The dissolving agent is a mixture of sodium thioglycolate and a primary dissolving agent, and the mass ratio of the sodium thioglycolate to the primary dissolving agent is 1.2:0.4;

[0049] The preparation method of the primary dissolving agent is as follows: 5.5g of diethylenetriamine and 1.4g of propylene glycol are mixed, the temperature is raised to 60°C and stirred, and after stirring evenly, an aminating agent is prepared; 18mL of 30wt% ethanol solution is introduced into a closed container, 6.5g of citric acid is added, and after stirring evenly, 3.2g of the aminating agent is added at a rate of 1.2mL / min, and stirring is performed while adding, and the stirring speed is 335rpm. After the addition is completed, the temperature is raised to 82°C at a rate of 1.8°C / min, and the reaction is refluxed for 18h. After the reaction is completed, the primary dissolving agent is prepared by cooling, filtering, washing, and drying.

[0050] 2. Roasting

[0051] The prefabricated rice husk was heated to 450°C at a rate of 12°C / min, roasted at 450°C for 30 minutes, then heated to 695°C at a rate of 10°C / min, roasted at 695°C for 2.7 hours, taken out after roasting, ground to a particle size of 70 mesh, and obtained rice husk ash.

[0052] 3. Synthesis reaction

[0053] Add 95 g of rice husk ash and 3400 mL of sodium hydroxide solution to a reaction container, then add 0.50 g of hyaluronic acid and 0.52 g of glucomannan, stir evenly, raise the temperature to 118° C. at a rate of 3.8° C. / min, perform step-by-step reaction at 118° C., the pressure is 0.63 MPa, the reaction time is 2.4 h, and after the reaction is completed, naturally cool to room temperature, and obtain a sodium silicate solution through precipitation, stratification, and vacuum filtration;

[0054] The concentration of the sodium hydroxide solution is 1.4 mol / L;

[0055] In the stepwise reaction, the stirring speed was controlled at 270 rpm in the first 20 min of the reaction, at 330 rpm in the last 20 min of the reaction, and at 780 rpm for the rest of the time.

[0056] Example 3

[0057] 1. Preprocessing

[0058] 62 g of rice husk was placed in 330 g of deionized water for cleaning, filtered and dried, and then 1800 mL of pretreatment agent and 6.3 g of chaotropic agent were added for ultrasonic soaking treatment. The ultrasonic soaking time was 3.8 h, the ultrasonic power was 420 W, the ultrasonic frequency was 33 kHz, and the temperature was 72 ° C. After the soaking, the rice husk was centrifuged and filtered at a speed of 4300 rpm for 27 min. After washing, the rice husk was dried at 105 ° C for 1.8 h to obtain prefabricated rice husk.

[0059] The pretreatment agent is a 10.4wt% citric acid solution;

[0060] The dissolution agent is a mixture of sodium thioglycolate and a primary dissolution agent, and the mass ratio of the sodium thioglycolate to the primary dissolution agent is 0.8:0.4;

[0061] The preparation method of the primary dissolving agent is as follows: 5.8g of diethylenetriamine and 1.6g of propylene glycol are mixed, the temperature is raised to 64°C and stirred, and after stirring evenly, an aminating agent is prepared; 22mL of 30wt% ethanol solution is introduced into a closed container, 6.7g of citric acid is added, and after stirring evenly, 3.6g of the aminating agent is added at a rate of 1.4mL / min, and stirring is performed while adding, and the stirring speed is 345rpm. After the addition is completed, the temperature is raised to 86°C at a rate of 2.2°C / min, and the reaction is refluxed for 22h. After the reaction is completed, the primary dissolving agent is prepared by cooling, filtering, washing, and drying.

[0062] 2. Roasting

[0063] The prefabricated rice husk was heated to 470°C at a rate of 15°C / min, roasted at 470°C for 20 minutes, then heated to 705°C at a rate of 14°C / min, roasted at 705°C for 2.3 hours, taken out after roasting, ground to a particle size of 90 mesh, and obtained rice husk ash.

[0064] 3. Synthesis reaction

[0065] Add 105 g of rice husk ash and 3600 mL of sodium hydroxide solution to a reaction container, then add 0.46 g of hyaluronic acid and 0.56 g of glucomannan, stir evenly, raise the temperature to 123° C. at a rate of 4.2° C. / min, perform step-by-step reaction at 123° C., the pressure is 0.67 MPa, the reaction time is 2.6 h, and after the reaction is completed, naturally cool to room temperature, and obtain a sodium silicate solution through precipitation, stratification, and vacuum filtration;

[0066] The concentration of the sodium hydroxide solution is 1.6 mol / L;

[0067] In the stepwise reaction, the stirring speed was controlled at 300 rpm in the first 20 min of the reaction, at 350 rpm in the last 20 min of the reaction, and at 820 rpm for the rest of the time.

[0068] Comparative Example 1

[0069] Based on Example 1, the changes are as follows:

[0070] (1) In the pretreatment step, the solvent-activating component is omitted; the solvent-activating component is replaced by a pretreatment agent component in an equal amount, wherein the pretreatment agent is a 10 wt % citric acid solution;

[0071] (2) The synthetic reaction step is to add 100g of rice husk ash and 3500mL of sodium hydroxide solution into a reaction container, then add 0.15g of hyaluronic acid and 0.1g of glucomannan, stir evenly, raise the temperature to 120°C at a rate of 4.0°C / min, react at 120°C, stir at 800rpm, and at a pressure of 0.65MPa for 2.5h. After the reaction is completed, the temperature is naturally lowered to room temperature, and a sodium silicate solution is obtained by precipitation, stratification, and vacuum filtration.

[0072] The rest of the operations are the same.

[0073] Comparative Example 2

[0074] Based on Example 1, the changes are as follows:

[0075] (1) In the pretreatment step, the primary solubilizing agent component is omitted; the primary solubilizing agent is replaced by sodium thioglycolate in equal amounts;

[0076] (2) In the synthesis reaction step, hyaluronic acid and glucomannan components are omitted; equal amounts of hyaluronic acid and glucomannan are replaced with sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is 1.5 mol / L;

[0077] The rest of the operations are the same.

[0078] Performance Testing

[0079] Equal amounts of the prefabricated rice husks obtained in Examples 1-3 and Comparative Examples 1-2, the soaking liquid obtained after centrifugal filtration in the pretreatment step, the rice husk ash, and the sodium silicate product were taken to perform performance test experiments. Each group of test experiments was performed 3 times, and the average value was taken. The specific method is as follows:

[0080] (1) Whiteness

[0081] The rice husk ash obtained in Examples 1-3 and Comparative Examples 1-2 was measured using a SBD-1B digital whiteness meter;

[0082] (2) Silica dissolution rate

[0083] The calculation formula is P = AM1 / BM2 × 100% based on the ratio of the silica content in the prepared sodium silicate solution to the silica content in the rice husk ash;

[0084] Where A is the mass fraction of SiO2 in the sodium silicate solution, B is the mass fraction of SiO2 in the rice husk ash, M1 is the mass of the sodium silicate solution, and M2 is the mass of the rice husk ash before the reaction;

[0085] (3) Modulus

[0086] The sodium silicate solutions prepared in Examples 1-3 and Comparative Examples 1-2 were measured for modulus according to the method of "GB / T 4209-2008 Industrial Sodium Silicate";

[0087] (4) Metal impurity leaching rate

[0088] The calculation formula for the leaching rate c (%) of K, Na, and Ca in rice husk is c = a × V / (m × b) × 100%;

[0089] Wherein, b is the content of K, Na and Ca in the original rice husk measured by digestion method (mg / g); A is the content of K, Na and Ca in the soaking solution (mg / L); V is the volume of the soaking solution (L); and m is the mass of the original rice husk (g).

[0090] The specific performance test results are as follows:

[0091]

[0092] The invention uses rice husk as raw material to prepare sodium silicate, and performs pretreatment by using a pretreatment agent and a dissolving agent. As the pretreatment proceeds, the leaching rate of metal impurities will continuously decrease. After the dissolving agent is added, the primary dissolving agent and sodium thioglycolate cooperate to be adsorbed on the surface of the rice husk by means of hydrogen bonding, thereby reducing interfacial tension, enhancing contact and diffusion with the pretreatment agent, promoting the reaction between the metal impurities and the pretreatment agent, improving the leaching rate and leaching effect of the metal impurities, and thus improving the specific surface area and micropore volume of the rice husk ash, and further improving the whiteness and activity of the rice husk ash and the purity of silicon dioxide. The primary dissolving agent is a propylene glycol-vinyl alcohol catalyst. The triamine is used for dispersion, and the amino group on it reacts with the carboxyl group of citric acid for acylation reaction. The obtained primary dissolving agent has more hydroxyl, carboxyl and amino groups, and has good stability. It can efficiently and stably form hydrogen bonds with rice husks, and effectively promote the pretreatment step. In the synthesis reaction step, hyaluronic acid and glucomannan are added, which can be adsorbed on the surface of sodium silicate, can prevent the mutual aggregation and collision between sodium silicates, thereby avoiding its agglomeration and sedimentation. Combined with the step-by-step stirring dissolution-promoting method, the dispersibility of the reaction raw materials and reaction products in the reaction solution is further improved, so that the synthesis reaction is more complete, which is conducive to obtaining a sodium silicate product with higher quality.

[0093] In the pretreatment step of Comparative Example 1, the dissolution agent is omitted. As the pretreatment proceeds, the leaching rate of the metal impurities will continue to decrease, thereby causing incomplete reaction between the metal impurities and the pretreatment agent, and poor leaching rate and leaching effect of the metal impurities. In addition, in the synthesis reaction step of Comparative Example 1, a one-step reaction method is also used, which makes the synthesis reaction incomplete, ultimately reducing the whiteness of the rice husk ash, the dissolution rate of silicon dioxide is low, the leaching of metal impurities is less, and the product modulus is low;

[0094] In Comparative Example 2, in the pretreatment step, the primary dissolution agent was replaced with sodium thioglycolate in equal amounts, which reduced the dissolution-promoting effect and the leaching of metal impurities. The whiteness of the rice husk ash was slightly higher, and the purity of the silicon dioxide was reduced. The dispersant component was also omitted, which increased the probability of collision and aggregation between the sodium silicate products, resulted in obvious sedimentation, poor dispersion of the reaction materials, incomplete synthesis reaction, and poor overall performance of the obtained product.

[0095] Unless otherwise specified, all ratios and percentages described in the present invention are by mass ratios and percentages are by mass percentages.

[0096] 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 method for preparing sodium silicate using rice husks, characterized in that: It includes pretreatment, calcination and synthesis reaction steps; The pretreatment step comprises: washing the rice husk in deionized water, filtering and drying, adding a pretreatment agent and a dissolving agent, and performing ultrasonic soaking treatment. After the soaking, the pretreatment agent is centrifuged, filtered, washed, and dried to obtain the prefabricated rice husk; The mass volume ratio of the rice husk, deionized water, pretreatment agent and dissolution promoter is 58-62g:320-330g:1760-1800mL:5.8-6.3g; The dissolving agent is a mixture of sodium thioglycolate and a primary dissolving agent, and the mass ratio of the sodium thioglycolate to the primary dissolving agent is 0.8-1.2:0.4; The preparation method of the primary solubilizing agent is as follows: diethylenetriamine and propylene glycol are mixed, the temperature is raised to 60-64° C., and the mixture is stirred evenly to obtain an aminating agent; a 30wt% ethanol solution is introduced into a closed container, citric acid is added, and the mixture is stirred evenly, and then the aminating agent is added at a rate of 1.2-1.4 mL / min, and the mixture is stirred at a speed of 335-345 rpm. After the addition is completed, the mixture is heated to 82-86° C. at a rate of 1.8-2.2° C. / min, and the mixture is refluxed for reaction for 18-22 hours. After the reaction is completed, the mixture is cooled, filtered, washed, and dried to obtain the primary solubilizing agent; The mass ratio of diethylenetriamine to glycerol is 5.5-5.8:1.4-1.6; The mass volume ratio of the ethanol solution, citric acid, and aminating agent is 18-22 mL: 6.5-6.7 g: 3.2-3.6 g; The roasting step comprises heating the prefabricated rice husk to 450-470° C. at a rate of 12-15° C. / min, roasting at 450-470° C. for 20-30 min, then heating to 695-705° C. at a rate of 10-14° C. / min, roasting at 695-705° C. for 2.3-2.7 h, taking out the prefabricated rice husk after roasting, and grinding it to a particle size of 70-90 meshes to obtain rice husk ash; The synthesis reaction step comprises adding rice husk ash and sodium hydroxide solution to a reaction container, then adding hyaluronic acid and glucomannan, stirring evenly, raising the temperature to 118-123° C. at a rate of 3.8-4.2° C. / min, and performing step-by-step reaction. After the reaction is completed, the temperature is naturally lowered to room temperature, and a sodium silicate solution is obtained by precipitation, stratification, and vacuum filtration. The mass volume ratio of the rice husk ash, sodium hydroxide solution, hyaluronic acid and glucomannan is 95-105g:3400-3600mL:0.46-0.50g:0.52-0.56g; the step-by-step reaction has a reaction temperature of 118-123°C, a pressure of 0.63-0.67MPa, a reaction time of 2.4-2.6h, and a stirring speed of 270-300rpm in the first 20min of the reaction, and a stirring speed of 330-350rpm in the last 20min of the reaction, and a stirring speed of 780-820rpm in the rest of the time.

2. The method for preparing sodium silicate using rice husk according to claim 1, characterized in that: In the pretreatment step, the ultrasonic immersion treatment is performed with an ultrasonic immersion time of 3.3-3.8 h, an ultrasonic power of 380-420 W, an ultrasonic frequency of 27-33 kHz, and a temperature of 68-72° C. The centrifugal filtration has a rotation speed of 3800-4300 rpm and a time of 23-27 min; The drying temperature is 95-105° C. and the drying time is 1.8-2.3 hours.

3. The method for preparing sodium silicate using rice husk according to claim 1, characterized in that: In the pretreatment step, the pretreatment agent is a 9.6-10.4 wt % citric acid solution.

4. The method for preparing sodium silicate using rice husk according to claim 1, characterized in that: In the synthesis reaction step, the concentration of the sodium hydroxide solution is 1.4-1.6 mol / L.

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