A production process of silica micro powder for rubber prepared from rice husk ash

Abstract

The application discloses a production process of silica micro powder for rubber prepared from rice husk ash, and belongs to the technical field of rice husk ash resource utilization. Firstly, the production process comprises the following steps: the rice husk ash is pretreated by hydrochloric acid and cassava starch, then is treated by a purified solution, calcined, treated by a DBD reactor, mixed with an ethanol solution and the like, ultrasonically dispersed, centrifuged, dried and sieved, and room temperature drying is carried out to obtain the silica micro powder for rubber. The application successfully solves the problems of low purity, poor dispersibility and high energy consumption of the silica micro powder in the prior art through multi-step innovations such as acid immersion-template agent cooperation, microwave-complexation purification, plasma activation and composite surface modification. The test data of the embodiments show that the silica micro powder of the application is significantly better than the comparative examples and the prior art in reinforcing property, dispersibility, wear resistance and aging resistance, and has environmental protection and economy, and has a wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rice husk ash resource utilization, and particularly relates to a production process of silica micro powder for rubber prepared from rice husk ash. BACKGROUND

[0002] The silica micro powder is an important reinforcing filler in rubber products, and can significantly improve the mechanical properties and wear resistance of rubber. At present, industrial-grade silica is mainly prepared by high-temperature melting method or chemical precipitation method. However, there are problems such as high energy consumption and non-renewable raw materials. The rice husk ash, as an agricultural waste, is rich in amorphous silica (content of about 90% to 95%), and has the advantages of low cost and renewable. However, the high impurity content and uneven particle size distribution limit its application in rubber.

[0003] In the prior art, the process for preparing silica micro powder from rice husk ash mainly adopts single acid leaching or alkali melting method, and has the following technical problems:

[0004] (1) Although the acid leaching method can remove metal impurities (such as Fe and Al oxides), the residual acid liquid can easily cause the failure of the subsequent surface modifier;

[0005] (2) The alkali melting method needs high-temperature (> 800℃) calcination, which has high energy consumption and generates crystalline silica, and the reinforcing effect is poor;

[0006] (3) The silica micro powder prepared by the existing process has poor dispersibility in rubber, and easily causes filler agglomeration, which leads to the decrease of the tear strength of rubber products.

[0007] With the increasing demand for low-cost and high-performance fillers in the rubber industry, it is urgent to develop a green and efficient production process which can deeply remove the impurities of rice husk ash and also control the surface activity of silica, so that the silica has high reinforcing property and good dispersibility. SUMMARY

[0008] The purpose of the present application is to provide a production process of silica micro powder for rubber prepared from rice husk ash, to solve the problems in the background art.

[0009] The purpose of the present application can be achieved by the following technical solutions:

[0010] A production process of silica micro powder for rubber prepared from rice husk ash, comprising the following steps:

[0011] S1, adding 1.2 mol / L hydrochloric acid solution and cassava starch to the rice husk ash, heating to 50℃ and then constant temperature stirring for 2-4h, centrifugation, to obtain pretreated rice husk ash;

[0012] S2, adding the pretreated rice husk ash into the purification liquid, stirring at room temperature for 10-20 min, then heating to 45-50℃, treating by microwave with power of 800W for 30 min, after completion, collecting the solid component by filtration, then calcining the solid component at 500℃ for 2.0-2.5h, to obtain purified silica powder;

[0013] S3, treating the purified silica powder in the DBD reactor for 5 min, to obtain surface-treated silica powder;

[0014] S4, adding the surface-treated silica powder, polyethylene glycol-b-polyacrylic acid block copolymer and silane coupling agent KH-550 into the ethanol solution with mass fraction of 95%, stirring, heating to 50℃, ultrasonic dispersion for 30 min, drying after centrifugation, then passing through a 500 mesh sieve, and drying at room temperature for 24-48h, to obtain silica powder for rubber.

[0015] Further, the amount ratio of the rice husk ash, hydrochloric acid solution and cassava starch in S1 is 1kg:10-12L:100g.

[0016] Further, the SiO2 content in the rice husk ash in S1 is ≥92%, and the particle size of the rice husk ash is ≤100 mesh; the amylose content of the cassava starch is ≥30%.

[0017] Further, the purification liquid in S2 is configured by the following steps:

[0018] heating the deionized water to 55-60℃, adding citric acid into the deionized water while hot, stirring, magnetically stirring until the citric acid is completely dissolved, then cooling to 40-45℃, adding disodium EDTA into the deionized water while hot, stirring at constant temperature for 20-30 min, after completion, cooling to room temperature, supplementing deionized water, and adjusting the pH of the system to 3.4-4.0 by 1mol / L NaOH solution, to obtain the purification liquid.

[0019] Further, the amount ratio of the deionized water, citric acid and disodium EDTA is 1L:57.6-58.0g:29.8-30.0g.

[0020] Further, the amount ratio of the purification liquid and the pretreated rice husk ash in S2 is 1L:200g.

[0021] Further, the discharge power of the DBD reactor in S3 is 200W, the working gas is argon, and the argon flow rate is set to 2L / min.

[0022] Further, the amount ratio of the ethanol solution, surface-treated silica powder, polyethylene glycol-b-polyacrylic acid block copolymer and silane coupling agent KH-550 is 1L:100g:1.5-2.0g:1g.

[0023] Advantages of the present application:

[0024] The present application provides a production process for preparing silica micro powder for rubber from rice hull ash. The present application significantly improves the purity, dispersibility and reinforcing performance of silica micro powder through multi-step synergistic treatment, while solving the problems of high energy consumption, complex process and environmental pollution in the prior art. The advantages of the present application are described in detail from the aspects of technical advantages, performance improvement and environmental protection.

[0025] 1. Technical advantages: multi-step synergistic treatment significantly improves product performance:

[0026] Acid leaching combined with template agent: in the pretreatment step (S1), the present application uses hydrochloric acid solution and cassava starch to synergistically treat rice hull ash. Hydrochloric acid effectively removes metal impurities (such as Fe, Al oxides), and cassava starch as a porous template agent forms a hierarchical pore structure during subsequent calcination, increasing the specific surface area of silica and thus improving its reinforcing performance. The absence of cassava starch in Comparative Example 1 resulted in a significant decrease in 300% modulus of elasticity (9.8 MPa vs. 12.8 MPa), demonstrating the key role of the template agent.

[0027] Microwave-complexation synergistic purification: in step S2, the present application uses a purification solution prepared from citric acid and disodium EDTA combined with microwave treatment to efficiently complex and remove residual metal impurities. Microwave treatment (800 W) significantly improves reaction efficiency, avoiding the high energy consumption problem of traditional high-temperature calcination (> 800℃). In Comparative Example 5, water bath heating was used instead of microwave treatment, resulting in a significantly higher wear amount (0.28 cm 3 / 1.61 km) than Example 3 (0.16 cm 3 / 1.61 km), indicating the necessity of microwave treatment.

[0028] Plasma surface activation: in step S3, a DBD reactor is used to treat the silica micro powder with plasma, activating the surface hydroxyl groups and improving the grafting rate of subsequent silane coupling agents. Comparative Example 3, which did not undergo plasma treatment, had an ozone resistance time (160 h) significantly lower than Example 3 (230 h), indicating that plasma treatment is crucial for improving the aging resistance of rubber.

[0029] Composite surface modification: in step S4, polyethylene glycol-b-polyacrylic acid block copolymer and silane coupling agent KH-550 synergistically improve the dispersibility of silica in rubber. Comparative Example 4, which did not use block copolymer, had a higher Mooney viscosity (57 MU) than Example 3 (47 MU), indicating the important contribution of block copolymer to dispersibility.

[0030] 2. Performance improvement: comprehensive optimization of reinforcing performance, dispersibility and wear resistance:

[0031] Reinforcing property: the 300% modulus of Example 3 reached 12.8 MPa, much higher than that of Comparative Examples 1-5 (9.8-10.9 MPa), indicating that the multi-step synergistic treatment of the present application significantly improved the reinforcing effect of silica.

[0032] Dispersion: the Mooney viscosity of Example 3 was only 47 MU, much lower than that of Comparative Examples 1-5 (56-60 MU), indicating that the dispersion of silica in rubber was excellent, avoiding the problem of filler aggregation.

[0033] Wear resistance and aging resistance: the abrasion amount (0.16 cm 3 / 1.61 km) and ozone resistance time (230 h) of Example 3 were better than those of the comparative examples, proving that its wear resistance and aging resistance were significantly improved, suitable for high-performance rubber products.

[0034] 3. Environmental friendliness: green process and resource recycling:

[0035] Raw material greenization: using rice husk ash as raw material, high-value utilization of agricultural waste is realized, avoiding the use of non-renewable resources such as quartz sand.

[0036] Low energy consumption process: microwave treatment and calcination at 500℃ instead of traditional high-temperature alkali fusion method (>800℃), energy consumption reduced by more than 30%, in line with green manufacturing requirements.

[0037] No harmful residue: through the purification liquid and plasma treatment, the problem of surface modification failure caused by residual acid liquid in acid leaching method is avoided.

[0038] Summary: through the multi-step innovation of acid leaching-template agent synergy, microwave-complex purification, plasma activation and composite surface modification, the present application successfully solves the problems of low purity, poor dispersion and high energy consumption of silica powder in the prior art. The test data of the examples show that the silica powder of the present application is significantly better than the comparative examples and the prior art in reinforcing property, dispersion, wear resistance and aging resistance, and has environmental friendliness and economy, which has broad industrial application prospect. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] Example 1

[0041] A production process for preparing a silica powder for rubber from rice husk ash, comprising the following steps:

[0042] S1, Pretreatment: 1 kg of rice husk ash (SiO2 content ≥ 92%, particle size ≤ 100 mesh, commercially available) was taken and 10 L of 1.2 mol / L hydrochloric acid solution and 100 g of cassava starch (commercially available, food grade, linear content ≥ 30%) were added thereto under stirring. The system was heated to 50°C and then stirred at constant temperature for 2 h. After completion, the pretreated rice husk ash was collected by centrifugation. The soluble metal impurities in the rice husk ash were removed by hydrochloric acid pretreatment, and cassava starch was introduced as a porous template agent. The porosity generated by the high-temperature carbonization of cassava starch was used to guide the formation of hierarchical pore structure of silicon dioxide, thereby improving the specific surface area.

[0043] S2, Configuration of Purification Solution: 800 mL of deionized water was taken and heated to 55°C. 57.6 g of citric acid (analytical pure, commercially available) was added thereto under stirring while hot. Magnetic stirring was performed until the citric acid was completely dissolved. The temperature was then lowered to 40°C. 29.8 g of disodium EDTA (reagent grade, 97%) was added thereto under stirring while hot. Constant temperature stirring was performed for 20 min. After completion, the temperature was cooled to room temperature. Deionized water was added to make the total volume 1 L. 1 mol / L NaOH solution was used to adjust the pH of the system to 3.4 (to avoid precipitation of citric acid and disodium EDTA). After completion, the purification solution was obtained.

[0044] S3, Microwave-Complexation Synergistic Purification: 200 g of pretreated rice husk ash was added to 1 L of the purification solution under stirring. The system was stirred at room temperature for 10 min and then heated to 45°C. Microwave treatment (power 800 W) was performed for 30 min. Microwave treatment can promote the dissociation of metal impurities from the complex. After completion, the solid components were collected by filtration. The solid components were then calcined in a muffle furnace at 500°C for 2.0 h to remove the cassava starch template. After completion, the purified silica powder was obtained.

[0045] S4, Plasma Treatment: The purified silica powder was placed in a DBD reactor for treatment for 5 min. The discharge power was 200 W, the working gas was argon, and the argon flow rate was set to 2 L / min. Through plasma pretreatment, the surface hydroxyl groups of the silica were activated, thereby improving the grafting rate of the subsequent silane coupling agent.

[0046] S5, Surface Modification: 100 g of surface-treated silica powder, 1.5 g of polyethylene glycol-b-polyacrylic acid block copolymer (PEG-b-PAA, Mn = 5000, commercially available), and 1 g of silane coupling agent KH-550 (amino type, commercially available) were added to 1 L of 95% ethanol solution under stirring. The system was heated to 50°C and ultrasonically dispersed (frequency 28 kHz) for 30 min. After centrifugal drying, it was sieved through a 500 mesh sieve and then dried at room temperature for 24 h. The rubber silica powder was obtained.

[0047] Example 2

[0048] A production process of silica micro powder for rubber prepared from rice husk ash, comprising the following steps:

[0049] S1, pretreatment: take 1 kg of rice husk ash (SiO2 content ≥ 92%, particle size ≤ 100 mesh, commercially available), add 11 L of 1.2 mol / L hydrochloric acid solution and 100 g of cassava starch (commercially available, food grade, linear content ≥ 30%) to it, heat the system to 50°C and then constant temperature stirring for 4h, after completion, centrifugal collection to obtain pretreated rice husk ash, through hydrochloric acid pretreatment to remove soluble metal impurities in the rice husk ash, and introduce cassava starch as a porous template agent, use the pores generated by high temperature carbonization of cassava starch to guide the formation of hierarchical pore structure of silicon dioxide, and improve the specific surface area.

[0050] S2, configure the purification liquid: take 800 mL of deionized water, heat to 60°C, while hot, add 58.0 g of citric acid (analytical pure, commercially available) to it with stirring, magnetically stir until the citric acid is completely dissolved, then cool to 40°C, while hot, add 30.0 g of disodium EDTA (reagent grade, 97%) to it with stirring, constant temperature stirring for 30 min, after completion, cool to room temperature, add deionized water to a total volume of 1 L, then adjust the pH of the system to 3.5 with 1 mol / L NaOH solution (to avoid precipitation of citric acid and disodium EDTA), after completion, the purification liquid is obtained.

[0051] S3, microwave-complexation synergistic purification: add 200 g of pretreated rice husk ash to 1 L of the purification liquid with stirring, stir at room temperature for 20 min, then heat to 45°C, then microwave treatment (power 800W) for 30 min, microwave treatment can promote the dissociation of metal impurities from the complex, after completion, filter the solid components, then place the solid components in a muffle furnace at 500°C for 2.5h to remove the cassava starch template, after completion, the purified silica micro powder is obtained.

[0052] S4, plasma treatment: place the purified silica micro powder in a DBD reactor for 5 min to obtain surface-treated silica micro powder, wherein the discharge power is 200W, the working gas is argon, and the argon flow rate is set to 2L / min. Through plasma pretreatment, the surface hydroxyl groups of the silica are activated, and the grafting rate of the subsequent silane coupling agent is improved.

[0053] S5, surface modification: 100 g of the surface-treated silica fume, 1.8 g of polyethylene glycol-b-polyacrylic acid block copolymer (PEG-b-PAA, Mn = 5000, commercially available) and 1 g of silane coupling agent KH-550 (amino type, commercially available) were added into 1 L of 95% mass fraction ethanol solution under stirring, and the system was ultrasonically dispersed (frequency 28 kHz) at 50 °C for 30 min. After centrifugal drying, it was sieved through a 500 mesh sieve, and then dried at room temperature for 48 h to obtain the silica fume for rubber.

[0054] Example 3

[0055] A production process of silica fume for rubber prepared from rice husk ash, comprising the following steps:

[0056] S1, pretreatment: 1 kg of rice husk ash (SiO2 content ≥ 92%, particle size ≤ 100 mesh, commercially available) was taken, and 12 L of 1.2 mol / L hydrochloric acid solution and 100 g of cassava starch (commercially available, food grade, linear content ≥ 30%) were added into it under stirring. The system was heated to 50 °C and then stirred at constant temperature for 4 h. After completion, the pretreated rice husk ash was collected by centrifugation. The soluble metal impurities in the rice husk ash were removed by hydrochloric acid pretreatment, and the cassava starch was introduced as a porous template. The pores generated by the high-temperature carbonization of cassava starch were used to guide the formation of hierarchical pore structure of silica, thereby improving the specific surface area.

[0057] S2, preparation of purification solution: 800 mL of deionized water was taken and heated to 60 °C. 58.0 g of citric acid (analytically pure, commercially available) was added into it under stirring while hot. Magnetic stirring was performed until the citric acid was completely dissolved. Then the temperature was lowered to 45 °C. 30.0 g of disodium EDTA (reagent grade, 97%) was added into it under stirring while hot. Constant temperature stirring was performed for 30 min. After completion, it was cooled to room temperature. Deionized water was added to make the total volume 1 L. 1 mol / L NaOH solution was used to adjust the pH of the system to 4.0 (to avoid precipitation of citric acid and disodium EDTA). After completion, the purification solution was obtained.

[0058] S3, microwave-complexation synergistic purification: 200 g of pretreated rice husk ash was added into 1 L of the purification solution under stirring. The system was stirred at room temperature for 20 min, and then heated to 50 °C. Microwave treatment (power 800 W) was performed for 30 min. Microwave treatment can promote the dissociation of metal impurities from the complex. After completion, the solid components were collected by filtration. The solid components were calcined at 500 °C in a muffle furnace for 2.5 h to remove the cassava starch template. After completion, the purified silica fume was obtained.

[0059] S4, Plasma treatment: the purified silica powder was placed in the DBD reactor for 5 min to obtain surface-treated silica powder, wherein the discharge power was 200 W, the working gas was argon, and the argon flow rate was set to 2 L / min. The surface hydroxyl groups of the silica were activated by plasma pretreatment to improve the subsequent grafting rate of the silane coupling agent.

[0060] S5, Surface modification: 100 g of the surface-treated silica powder, 2.0 g of polyethylene glycol-b-polyacrylic acid block copolymer (PEG-b-PAA, Mn = 5000, commercially available), and 1 g of silane coupling agent KH-550 (amino type, commercially available) were added to 1 L of an ethanol solution with a mass fraction of 95% while stirring. The system was heated to 50°C and ultrasonically dispersed (frequency 28 kHz) for 30 min. After centrifugal drying, it was sieved through a 500-mesh sieve and then dried at room temperature for 48 h to obtain the silica powder for rubber.

[0061] Comparative Example 1

[0062] Comparative Example 1 is a control group of Example 3. The raw material 100 g of cassava starch in S1 of Example 3 was removed, and the remaining raw materials, raw material amounts, and production process steps were consistent with those in Example 3. Finally, the silica powder for rubber was obtained.

[0063] Comparative Example 2

[0064] Comparative Example 2 is a control group of Example 3. S2 in Example 3 was deleted, and the purified liquid in S3 was replaced with a 0.5 mol / L citric acid solution. The remaining raw materials, raw material amounts, and production process steps were consistent with those in Example 3. Finally, the silica powder for rubber was obtained.

[0065] Comparative Example 3

[0066] Comparative Example 3 is a control group of Example 3. S4 in Example 3 was deleted, and the surface-treated silica powder in S5 was replaced with the purified silica powder of step S3. The remaining raw materials, raw material amounts, and production process steps were consistent with those in Example 3. Finally, the silica powder for rubber was obtained.

[0067] Comparative Example 4

[0068] Comparative Example 4 is a control group of Example 3. The raw material 2.0 g of polyethylene glycol-b-polyacrylic acid block copolymer in S5 of Example 3 was removed. The remaining raw materials, raw material amounts, and production process steps were consistent with those in Example 3. Finally, the silica powder for rubber was obtained.

[0069] Comparative Example 5

[0070] Comparative Example 5 is a control group of Example 3, in which the microwave treatment process in S3 in Example 3 is replaced by water bath heating at 50℃ for 2h, and the rest of the raw materials, raw material amounts, and production process steps remain the same as in Example 3, and finally the silica powder for rubber is obtained.

[0071] Test Example 1

[0072] The silica powder for rubber prepared in Examples 1-3 and Comparative Examples 1-5 is subjected to performance testing, and the performance testing process is as follows:

[0073] (1) Preparation of the rubber to be tested:

[0074] Raw materials (mass parts): 100 parts of natural rubber (NR, Mooney viscosity ML(1+4)100℃=60±5); 2.5 parts of sulfur (industrial grade, purity≥99.5%, particle size≤75μm); 1.5 parts of accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide, reagent grade, purity≥98%); 5 parts of zinc oxide (nanoscale, particle size 30±5nm, specific surface area 35±5m 2 / g); 2 parts of stearic acid (food grade, iodine value≤2.0gI2 / 100g); 40 parts of the silica powder to be tested (silica powder for rubber prepared in Examples 1-3 and Comparative Examples 1-5).

[0075] Mixing process: The above raw materials are weighed according to mass parts, and the natural rubber is thin-passed 3 times on an open mill (roller temperature 50±5℃) with a roller gap of 0.5mm. After wrapping the roller, stearic acid is added, and the left and right knives are each cut 3 times, and mixed for 5min. Then the silica powder to be tested is added in 3 portions with an interval of 2min, and mixed for 15min. Then zinc oxide is added, and mixed for 3min. Then accelerator CZ is added, and mixed for 2min. Finally, sulfur is added, and mixed for 4min. After completion, the roller gap is adjusted to 2.0mm to release the sheet, and a rubber sheet is obtained. The rubber sheet has a thickness of 2.0±0.1mm, and is left to stand at room temperature for 24h to eliminate internal stress, and a vulcanized rubber sheet is obtained.

[0076] Vulcanization molding: 5g of the vulcanized rubber sheet is used to determine the vulcanization time t90=8min35s (160℃) by a rotorless rheometer (ASTM D5289), and a 200×200×2mm 3 dumbbell-shaped mold (in accordance with GB / T528-2009) is preheated to 160℃, and the vulcanized rubber sheet is added thereto. A flat vulcanizing machine (pressure 15MPa, temperature 160±1℃) is used to press to 15MPa, and the vulcanization time is set to t90×1.1=9min30s. After vulcanization is completed, it is immediately cooled to room temperature in cold water, and then cut into dumbbell-shaped Type I samples (gauge length 25mm, width 6mm), and the rubber to be tested is obtained.

[0077] (2) Determination of the reinforcing performance of the rubber to be tested:

[0078] Standard: GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber"; test index: 300% modulus (MPa).

[0079] (3) Determination of the dispersing performance of the rubber to be tested:

[0080] Standard: GB / T 1232.1-2016 "Determination of unvulcanized rubber by disc type shear viscometer"; condition: ML (1+4) 100℃, record the Mooney viscosity (MU).

[0081] (4) Determination of the wear resistance of the rubber to be tested:

[0082] Standard: GB / T 1689-2014 "Determination of wear resistance of vulcanized rubber"; instrument: Akron abrasion tester, load 26.7N, test the abrasion amount (cm 3 / 1.61km).

[0083] (5) Determination of the anti-aging performance of the rubber to be tested:

[0084] Standard: GB / T 7762-2014 "Static tensile test for ozone cracking resistance of vulcanized or thermoplastic rubber"; condition: 50pphm ozone concentration, 40℃x20% elongation, record the crack appearance time, i.e. the anti-ozone time (h).

[0085] Table 1 Test results

[0086]

[0087]

[0088] It should be noted that in this text, such as the term "including, containing" or any other variant is intended to cover non-exclusive containing, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes the elements inherent to such process, method, article or equipment.

[0089] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A production process for rubber-grade silica micropowder prepared from rice husk ash, characterized in that, Includes the following steps: S1. Add 1.2 mol / L hydrochloric acid solution and cassava starch to rice husk ash, heat to 50℃ and stir at a constant temperature for 2-4 hours, centrifuge to obtain pretreated rice husk ash. S2. Add pretreated rice husk ash to the purified solution, stir at room temperature for 10-20 minutes, then heat to 45-50℃ and microwave at 800W for 30 minutes. After completion, filter and collect the solid component, and then calcine the solid component at 500℃ for 2.0-2.5 hours to obtain purified silica micro powder. S3. Place the purified silica micro powder in a DBD reactor and treat for 5 min to obtain surface-treated silica micro powder. S4. Add surface-treated silica micro powder, polyethylene glycol-b-polyacrylic acid block copolymer and silane coupling agent KH-550 to a 95% ethanol solution by stirring. Heat to 50℃ and ultrasonically disperse for 30 min. After centrifugation and drying, pass through a 500-mesh sieve and then dry at room temperature for 24-48 h to obtain silica micro powder for rubber. The purification solution described in S2 is prepared by the following steps: Heat deionized water to 55-60℃, and while it is hot, add citric acid while stirring. Stir magnetically until the citric acid is completely dissolved. Then cool to 40-45℃, and while it is hot, add disodium EDTA while stirring. Stir at a constant temperature for 20-30 minutes. After that, cool to room temperature, add more deionized water, and then adjust the pH of the system to 3.4-4.0 with 1 mol / L NaOH solution. After that, the purified solution is obtained. The ratio of deionized water, citric acid, and disodium EDTA is 1L:57.6-58.0g:29.8-30.0g.

2. The production process of rubber-grade silica micropowder prepared from rice husk ash according to claim 1, characterized in that, The ratio of rice husk ash, hydrochloric acid solution, and cassava starch used in S1 is 1kg:10-12L:100g.

3. The production process of rubber-grade silica micro-powder prepared from rice husk ash according to claim 1, characterized in that, The rice husk ash in S1 has a SiO2 content ≥92% and a particle size ≤100 mesh; the cassava starch has a linear content ≥30%.

4. The production process of rubber-grade silica micro-powder prepared from rice husk ash according to claim 1, characterized in that, The ratio of the purified solution to the pretreated rice husk ash in S2 is 1L:200g.

5. The production process of rubber-grade silica micro powder prepared from rice husk ash according to claim 1, characterized in that, The DBD reactor described in S3 has a discharge power of 200W, uses argon as the working gas, and sets the argon flow rate to 2L / min.

6. The production process of rubber-grade silica micropowder prepared from rice husk ash according to claim 1, characterized in that, The ratio of the ethanol solution, surface-treated silica micro powder, polyethylene glycol-b-polyacrylic acid block copolymer, and silane coupling agent KH-550 is 1L:100g:1.5~2.0g:1g.

Images