A method for preparing a silica matting agent using red mud or tetraethyl orthosilicate as a silicon source

Abstract

The application provides a method for preparing silica matting agent by taking red mud or tetraethyl orthosilicate as a silicon source, which takes a sodium silicate solution extracted from the red mud or a tetraethyl orthosilicate solution as the silicon source, and prepares an oil phase by taking alkyl, alcohol and a surfactant according to a proportion, and adds the silicon source solution of the water phase into the oil phase to form a mixed solution of the water phase and the oil phase, so that the mixed solution has a lipophilic effect before forming a gel. After adding a gelling agent to gel, a modifier is added to modify the surface of the gel, so that the surface of the gel is more hydrophilic. After drying and calcining, the surfactant is removed, so that the prepared silica matting agent has a larger pore volume and is more lipophilic. The method can improve the problems of the existing silica matting agent, such as poor matting rate, poor dispersibility, easy agglomeration and excessive use of organic reagents, and has the advantages of simple process, rich raw materials and easy industrial production.

Description

Technical Field

[0001] This invention belongs to the field of matting agent technology and relates to a method for preparing silica matting agent using red mud or tetraethyl orthosilicate as silicon source. Background Technology

[0002] Silica matting agents should have the following characteristics: (1) Good light transmittance: The refractive index of synthetic silica is 1.46, which is similar to that of most resins (1.4-1.6). It has good transparency when added to water. (2) High matting efficiency: Silica is a porous structure with small and controllable particle size. Therefore, it has a higher matting rate at the same addition amount. Usually, the desired effect can be achieved with an addition amount of 1-6%. A small addition amount will not affect other properties of the coating. (3) Relatively stable chemical properties: Synthetic silica has high purity and good chemical stability. It will not react with water or common acids and alkalis and will not affect the composition of the coating itself. (4) Easy to add: Silica contains hydroxyl groups on its surface and can also be organically modified on the surface. It can be well dispersed in both water-based and solvent-based coatings.

[0003] The main methods for preparing silica matting agents are the sol-gel method, the gas-phase method, and the precipitation method. The sol-gel method uses highly chemically active silicon compounds as precursors, such as silicates or esters. These raw materials are mixed uniformly in the liquid phase, and then acid is added to induce the hydrolysis of silicate ions. The resulting orthosilicic acids undergo dehydration condensation reactions, forming a transparent and stable sol system in solution. After sol aging, the colloidal particles slowly polymerize to form a three-dimensional network structure gel. Silica is obtained through aging, crushing, washing, hydrothermal treatment, drying, and pulverizing. The gas-phase method uses natural quartz sand as the main raw material, reacting it with sodium hydroxide or sodium carbonate at high temperature to produce sodium silicate, which is then crushed, washed, dried, and pulverized to obtain fumed silica. The precipitation method involves a precipitation reaction between acid and alkaline silicate solutions such as sodium silicate to prepare silica matting agents.

[0004] However, silica matting agents produced by the sol-gel method are prone to drawbacks such as low matting efficiency and poor dispersibility; the gas phase method for producing fumed silica requires high temperatures, places high demands on reagents and equipment, and is easily affected by the environment; the precipitation method for producing silica matting agents does not produce silica gel, but rather loose, flocculent silica particles. The silica particles obtained after filtration, washing, drying, and pulverization have relatively low purity, are prone to agglomeration, and have difficult-to-control morphology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing silica matting agents using red mud or tetraethyl orthosilicate as the silicon source, so as to solve the problems of poor extinction rate and easy agglomeration of existing silica matting agents.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Red mud is a highly alkaline solid waste residue produced as a byproduct of alumina extraction in the aluminum industry. It is typically dumped in the open, causing environmental pollution, water resource depletion, soil degradation, and ecological damage. However, red mud is mainly composed of compounds of elements such as Al, Fe, Si, and Ti, as well as other mixed mineral phases and compounds containing trace elements such as Ni, Cd, K, and Pb. It is a valuable and abundant secondary resource, making the high-value utilization of its valuable elements an important research direction.

[0007] Based on this, this application uses sodium silicate solution or tetraethyl orthosilicate solution (TEOS) extracted from red mud as the silicon source. An oil phase is prepared using alkanes, alcohols, and surfactants in a specific ratio. An aqueous silicon source solution is then added to the oil phase to form a mixed solution of the aqueous and oil phases, creating an oleophilic effect before gelation. After gelation with a gelling agent, a modifier is added to modify the gel surface, making it more hydrophilic. The surfactant is removed after drying and calcination, resulting in a silica matting agent with larger pore volume and greater oleophilicity. This improves upon existing silica matting agents' poor extinction rate, poor dispersibility, easy agglomeration, and excessive use of organic reagents. The process is simple, uses abundant raw materials, and is easy to industrialize.

[0008] Specifically, the method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source provided in this application includes: S01: Mix alcohols, alkanes and surfactants in a molar ratio of (0.1-0.9)*X : X : (3-4)*X and heat in a water bath for 0.5-2.0 h; add silicon source solution and continue the water bath reaction for 0.5-2.0 h to obtain a water-oil mixture; wherein X is 0.5-1.5, and the silicon source solution is sodium silicate solution or tetraethyl orthosilicate solution extracted from red mud.

[0009] Alcohols, alkanes, and surfactants were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, and then heated in a water bath at 10-30℃ for 0.5-2.0 h. After the reaction was completed, a silicon source solution was added, and the reaction was continued in the water bath for another 0.5-2.0 h to obtain a water-oil mixture. Here, X is 0.5-1.5. Preferably, the water bath reaction temperature is 20-30℃, and the reaction time before and after adding the silicon source solution is 0.5-1.0 h.

[0010] In this application, the surfactant not only significantly reduces the surface tension between alcohols, alkanes, and the silicon source solution, promoting their reaction, but also interacts with silicon molecules in the silicon source solution to form micelles. These micelles induce silica deposition through complex mechanisms such as liquid crystal templates and charge interactions. Finally, calcination removes the template molecules—the surfactant—achieving pore formation in the silica, resulting in silica with larger pore sizes and increased oleophilicity.

[0011] In this application, the surfactant includes any one or more of the following: hexadecyltrimethyl ammonium bromide (CTAB), ethanol, ethylenediaminetetraacetic acid (EDTA), sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), dodecyl polyglucoside (C12APG), and disodium ethylenediaminetetraacetic acid (EDTA-2Na).

[0012] In this application, alcohols include n-butanol or glycerol; alkanes include n-heptane or n-hexane.

[0013] In addition, the method for extracting sodium silicate from red mud in this application includes: S011: Red mud is mixed with hydrochloric acid with a concentration of 5.0-12.0 mol / L and reacted, and then filtered to obtain a solid containing Si.

[0014] To obtain a relatively pure Si-containing solid from red mud, this application uses a high-concentration hydrochloric acid to mix with the red mud. Specifically, the red mud is mixed with hydrochloric acid at a concentration of 5.0-12.0 mol / L, heated to 80-120°C, and stirred continuously for 1.0-4.0 h to obtain a reaction mixture. After cooling the reaction mixture to room temperature, it is separated by suction filtration through a Buchner funnel to obtain the Si-containing solid. Preferably, the concentration of hydrochloric acid is 5.0-8.0 mol / L, the heating temperature is 100°C, and the reaction time is 2.5 h.

[0015] S012: The Si-containing solid is ground and pulverized, then reacted with acid in an oil bath, cooled, and filtered to obtain a solid.

[0016] After grinding and pulverizing the Si-containing solid, the Si-containing solid is mixed with an acid with a concentration of 70-95% at a solid-liquid ratio of 1g:10mL, and then placed in an oil bath. The mixture is reacted at 90-130℃ for 0.5-4.0 h to obtain a reaction mixture. The reaction mixture is then separated by suction filtration through a Buchner funnel to obtain a solid. Preferably, the acid used in this application is hydrochloric acid, sulfuric acid, or nitric acid, the heating temperature is 90-110℃, and the reaction time is 2.0-4.0 h.

[0017] S013: The solid reacts with sodium hydroxide solution in an oil bath, and after cooling and centrifugation, sodium silicate solution is obtained.

[0018] A solid is mixed with a sodium hydroxide solution with a concentration of 2.0-7.0 mol / L at a solid-liquid ratio of 1 g:30 mL, and reacted in an oil bath at 90-130℃ for 0.5-4.0 h to obtain a reaction mixture. The reaction mixture is then centrifuged to obtain a sodium silicate solution. Preferably, the concentration of sodium hydroxide is 2.0-5.0 mol / L, the heating temperature is 90-110℃, and the reaction time is 2.0-4.0 h.

[0019] In this application, the method for preparing the tetraethyl orthosilicate solution includes: mixing tetraethyl orthosilicate, ethanol, and deionized water in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y until homogeneous; adding hydrochloric acid with a concentration of 0.1-1.0 mol / L; and reacting in a water bath at a temperature of 15-55℃ for 0.5-4.0 h to obtain the tetraethyl orthosilicate solution. Wherein, Y is 0.5-1.5. More preferably, the reaction temperature is 20-30℃, and the reaction time is 0.5-1.0 h.

[0020] S02: The gelling agent is slowly added dropwise to the water-oil mixture under continuous stirring, and a gel reaction occurs to form a gel; an aging agent and a modifier are added to the gel in sequence, and after drying and calcination, a silica matting agent is obtained; wherein, when the silicon source solution is a sodium silicate solution, the gelling agent is hydrochloric acid, and when the silicon source solution is a tetraethyl orthosilicate solution, the gelling agent is ammonia or sodium hydroxide.

[0021] The gelling agent is slowly added dropwise to a continuously stirred water-oil mixture, causing a slow gelation reaction to form a gel. When the silicon source solution is a sodium silicate solution, the gelling agent is hydrochloric acid with a concentration of 3.0-10.0 mol / L. When the silicon source solution is a tetraethyl orthosilicate solution, the gelling agent is ammonia or sodium hydroxide with a concentration of 0.1-1.0 mol / L.

[0022] An aging agent is added to the generated gel for aging treatment, wherein the aging agent includes any one or more of ethanol, TEOS, n-heptane and n-hexane.

[0023] A modifier is added to the aged gel, and the modification reaction is carried out at an oil bath temperature of 60-100℃ for 2.0-8.0 h to change the chemical composition and structure of the gel surface and improve the dispersibility of the final silica matting agent. In this application, the modifier includes any one or more of n-heptane, n-hexane, and trimethylchlorosilane (TMCS).

[0024] The modified gel was placed in an oven for segmented heating and drying to obtain a powder. The dried powder was then placed in a calcination furnace and calcined at 400-600℃ for 1.0-6.0 h to obtain a silica matting agent.

[0025] The present invention has the following beneficial effects: This invention provides a method for preparing a silica matting agent using red mud or tetraethyl orthosilicate as the silicon source. The method uses a sodium silicate solution or tetraethyl orthosilicate solution extracted from red mud as the silicon source, and employs a sol-gel method with aqueous and oil phases to prepare the silica matting agent by controlling the ratio of silicon source, acid or alkali.

[0026] (1) When the sodium silicate solution extracted from red mud is used as the silicon source, a large number of elements in the red mud can be removed by multi-stage acid leaching. Then, the silicon is converted into sodium silicate solution by sodium hydroxide. After pore-forming treatment, gel treatment, aging treatment and surface modification treatment, a silica matting agent with high hydrophobicity and high oil absorption value is prepared by sol-gel method of aqueous phase and oil phase, so as to better solve the red mud pollution and promote the high-value comprehensive utilization of red mud.

[0027] (2) When tetraethyl orthosilicate solution is used as silicon source, silica matting agent with high specific surface area, high amphiphilicity and high oil absorption value can be prepared directly by pore-forming treatment, gel treatment, aging treatment and surface modification treatment, and then by sol-gel method of aqueous phase and oil phase.

[0028] (3) The raw materials used in this preparation method are low in cost, the process is simple, easy to operate and easy to achieve large-scale industrial production. Attached Figure Description

[0029] Figure 1 The XRD (X-ray diffraction) spectrum of the silica matting agent prepared in Example 1 of this application is shown below. Figure 2 This is a hydrophilic contact angle test diagram of the silica matting agent prepared in Example 1 of this application; Figure 3This is a test diagram of the oleophilic contact angle of the silica matting agent prepared in Example 1 of this application; Figure 4 The XRD (X-ray diffraction) spectrum of the silica matting agent prepared in Example 6 of this application is shown below. Figure 5 This is a hydrophilic contact angle test diagram of the silica matting agent prepared in Example 6 of this application; Figure 6 This is a test diagram of the oleophilic contact angle of the silica matting agent prepared in Example 6 of this application; Figure 7 This is a BET specific surface area measurement diagram of the silica matting agent prepared in Example 1 of this application; Figure 8 This is a BET specific surface area measurement diagram of the silica matting agent prepared in Example 6 of this application; Figure 9 The BET specific surface area of ​​the silica matting agent prepared in Comparative Example 1 of this application is shown in the graph. Figure 10 This is a BET surface area measurement chart of the silica matting agent prepared in Comparative Example 2 of this application. Detailed Implementation

[0030] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0031] Example 1 This application provides a method for preparing a silica matting agent using tetraethyl orthosilicate solution as a silicon source, the method comprising: S101: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 1. Then, 0.1 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 25°C for 1.0 h to obtain a tetraethyl orthosilicate solution.

[0032] Butanol, hexane, and CTAB were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X is 1. The mixture was placed in a water bath at 30°C and heated for 0.5 h. After the reaction was complete, tetraethyl orthosilicate solution was added, and the reaction was continued in a water bath for another 1.0 h to obtain a water-oil mixture.

[0033] S102: 0.5 mol / L ammonia solution was slowly added dropwise to a continuously stirred water-oil mixture, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours of aging, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-heptane at a volume ratio of 1:5 were added to the aged gel, and the modification reaction was carried out at an oil bath temperature of 80℃ for 6.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder was placed in a calcination furnace and calcined at 550℃ for 4.0 hours in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0034] Example 2 This application provides a method for preparing a silica matting agent using tetraethyl orthosilicate solution as a silicon source, the method comprising: S201: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 0.5. Then, 1.0 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 30°C for 0.5 h to obtain a tetraethyl orthosilicate solution.

[0035] Glycerol, n-heptane, and SDBS were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X is 0.5. The mixture was placed in a water bath at 10°C and heated for 2.0 h. After the reaction was complete, tetraethyl orthosilicate solution was added, and the reaction was continued in the water bath for another 0.5 h to obtain a water-oil mixture.

[0036] S202: Sodium hydroxide (1.0 mol / L) is slowly added dropwise to a water-oil mixture under constant stirring, causing a slow gelation reaction to form a gel. The resulting gel is allowed to stand for 6 hours, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol (volume ratio 1:3) for 6 hours, and finally aged with n-heptane and ethanol (volume ratio 1:3) for 6 hours. TMCS and n-hexane (volume ratio 1:5) are added to the aged gel, and the modification reaction is carried out at an oil bath temperature of 60℃ for 8.0 hours. The modified gel is placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder is placed in a calcination furnace and calcined at 400℃ for 6.0 hours in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0037] Example 3 This application provides a method for preparing a silica matting agent using tetraethyl orthosilicate solution as a silicon source, the method comprising: S301: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 1.5. Then, 0.5 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 15℃ for 4.0 h to obtain a tetraethyl orthosilicate solution.

[0038] Butanol, hexane, and SDS were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X was 1.5. The mixture was placed in a water bath at 20°C and heated for 2.0 h. After the reaction was complete, tetraethyl orthosilicate solution was added, and the reaction was continued in the water bath for another 0.5 h to obtain a water-oil mixture.

[0039] S302: 0.5 mol / L ammonia solution is slowly added dropwise to a continuously stirred water-oil mixture, causing a slow gelation reaction to form a gel. The resulting gel is allowed to stand for 6 hours, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol (volume ratio 1:3) for 6 hours, and finally aged with n-heptane and ethanol (volume ratio 1:3) for 6 hours. TMCS and n-hexane (volume ratio 1:5) are added to the aged gel, and the mixture is modified at 100℃ in an oil bath for 2.0 hours. The modified gel is placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder is placed in a calcination furnace and calcined at 600℃ for 1.0 hour in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0040] Example 4 This application provides a method for preparing a silica matting agent using tetraethyl orthosilicate solution as a silicon source, the method comprising: S401: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 1. Then, 0.5 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 55°C for 0.5 h to obtain a tetraethyl orthosilicate solution.

[0041] Butanol, hexane, and CTAB were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X is 1. The mixture was placed in a water bath at 25°C and heated for 1.0 h. After the reaction was complete, tetraethyl orthosilicate solution was added, and the reaction was continued in a water bath for another 1.0 h to obtain a water-oil mixture.

[0042] S402: 5 mol / L ammonia solution was slowly added dropwise to a continuously stirred water-oil mixture, causing a slow gelation reaction to form a gel. The resulting gel was allowed to stand for 6 hours, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-heptane at a volume ratio of 1:5 were added to the aged gel, and the modification reaction was carried out at an oil bath temperature of 80℃ for 5.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder was placed in a calcination furnace and calcined at 500℃ for 3.0 hours in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0043] Example 5 This application provides a method for preparing a silica matting agent using tetraethyl orthosilicate solution as a silicon source, the method comprising: S501: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 1. Then, 0.8 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 40℃ for 3.0 h to obtain a tetraethyl orthosilicate solution.

[0044] Butanol, hexane, and PVP were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X is 1. The mixture was placed in a water bath at 25°C and heated for 1.0 h. After the reaction was complete, a silicon source solution was added, and the reaction was continued in the water bath for another 1.5 h to obtain a water-oil mixture.

[0045] S502: 0.8 mol / L ammonia solution is slowly added dropwise to a continuously stirred water-oil mixture, causing a slow gelation reaction to form a gel. The resulting gel is allowed to stand for 6 hours, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol (volume ratio 1:3) for 6 hours, and finally aged with n-heptane and ethanol (volume ratio 1:3) for 6 hours. TMCS and n-hexane (volume ratio 1:5) are added to the aged gel, and the mixture is modified at 80°C in an oil bath for 6.0 hours. The modified gel is placed in an oven and dried at 80°C for 2 hours, then heated to 100°C and dried for another 2 hours to obtain a powder. The dried powder is placed in a calcination furnace and calcined at 500°C for 5.0 hours in air at a heating rate of 5°C / min to obtain a silica matting agent.

[0046] Example 6 This application provides a method for preparing a silica matting agent using red mud as a silicon source, the method comprising: S601: Red mud was mixed with 7.0 mol / L hydrochloric acid, heated to 100℃, and stirred continuously for 2.5 h to obtain a reaction mixture. After cooling the reaction mixture to room temperature, it was separated by suction filtration through a Buchner funnel to obtain a Si-containing solid.

[0047] S602: After grinding and pulverizing the Si-containing solid, the Si-containing solid is mixed with 70% sulfuric acid at a solid-liquid ratio of 1g:10mL and placed in an oil bath. The mixture is then reacted at 110℃ for 2.0 h to obtain a reaction mixture. The reaction mixture is then separated by suction filtration through a Buchner funnel to obtain a solid.

[0048] S603: A solid was mixed with a 4.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 g: 30 mL, and reacted in an oil bath at 110 °C for 3.0 h to obtain a reaction mixture. The reaction mixture was then centrifuged to obtain a sodium silicate solution.

[0049] S604: Measure n-butanol, n-heptane, and CTAB according to the molar ratio (0.1-0.9)*X : X : (3-4)*X, where X is 1. Heat the mixture in a water bath at 30℃ for 0.5 h. After the reaction is complete, add sodium silicate solution and continue the reaction in the water bath for another 0.5 h to obtain a water-oil mixture.

[0050] S605: 5.0 mol / L hydrochloric acid was slowly added dropwise to a water-oil mixture under constant stirring, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-hexane at a volume ratio of 1:5 were added to the aged gel, and the mixture was modified at an oil bath temperature of 80℃ for 6.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder was placed in a calcination furnace and calcined at 550℃ for 4.0 hours in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0051] Example 7 This application provides a method for preparing a silica matting agent using red mud as a silicon source, the method comprising: S701: Red mud was mixed with 5.0 mol / L hydrochloric acid, heated to 120℃, and stirred continuously for 4.0 h to obtain a reaction mixture. After cooling the reaction mixture to room temperature, it was separated by suction filtration through a Buchner funnel to obtain a Si-containing solid.

[0052] S702: After grinding and pulverizing the Si-containing solid, the Si-containing solid is mixed with 95% sulfuric acid at a solid-liquid ratio of 1g:10mL and placed in an oil bath. The mixture is then reacted at 90℃ for 4.0 h to obtain a reaction mixture. The reaction mixture is then separated by suction filtration through a Buchner funnel to obtain a solid.

[0053] S703: A solid was mixed with a 2.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 g: 30 mL and reacted in an oil bath at 130 °C for 4.0 h to obtain a reaction mixture. The reaction mixture was then centrifuged to obtain a sodium silicate solution.

[0054] S704: Measure n-butanol, n-hexane, and EDTA according to the molar ratio (0.1-0.9)*X : X : (3-4)*X, where X is 0.5. Heat the mixture in a water bath at 10℃ for 2.0 h. After the reaction is complete, add sodium silicate solution and continue the reaction in the water bath for another 2.0 h to obtain a water-oil mixture.

[0055] S705: 3.0 mol / L hydrochloric acid was slowly added dropwise to a continuously stirred water-oil mixture, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours of aging, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-hexane at a volume ratio of 1:5 were added to the aged gel, and the modification reaction was carried out at an oil bath temperature of 60℃ for 8.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder was placed in a calcination furnace and calcined at 600℃ for 1.0 hour in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0056] Example 8 This application provides a method for preparing a silica matting agent using red mud as a silicon source, the method comprising: S801: Red mud was mixed with 12.0 mol / L hydrochloric acid, heated to 80°C, and stirred continuously for 1.0 h to obtain a reaction mixture. After cooling the reaction mixture to room temperature, it was separated by suction filtration through a Buchner funnel to obtain a Si-containing solid.

[0057] S802: After grinding and pulverizing the Si-containing solid, the Si-containing solid is mixed with 80% hydrochloric acid at a solid-liquid ratio of 1g:10mL and placed in an oil bath. The mixture is then reacted at 130℃ for 0.5 h to obtain a reaction mixture. The reaction mixture is then separated by suction filtration through a Buchner funnel to obtain a solid.

[0058] S803: A solid was mixed with a 7.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 g: 30 mL and reacted in an oil bath at 90 °C for 2.0 h to obtain a reaction mixture. The reaction mixture was then centrifuged to obtain a sodium silicate solution.

[0059] S804: Measure n-butanol, n-hexane, and SDBS according to the molar ratio (0.1-0.9)*X : X : (3-4)*X, where X is 1.5. Heat the mixture in a water bath at 20℃ for 2.0 h. After the reaction is complete, add sodium silicate solution and continue the reaction in the water bath for another 0.5-1.0 h to obtain a water-oil mixture.

[0060] S805: 10.0 mol / L hydrochloric acid was slowly added dropwise to a water-oil mixture under constant stirring, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours of aging, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-hexane at a volume ratio of 1:5 were added to the aged gel, and the mixture was modified at 100℃ in an oil bath for 2.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a powder. The dried powder was placed in a calcination furnace and calcined at 400℃ for 6.0 hours in air at a heating rate of 5℃ / min to obtain a silica matting agent.

[0061] Comparative Example 1 This comparative example provides a method for preparing a silica matting agent, the method comprising: D101: Tetraethyl orthosilicate, ethanol, and deionized water are mixed evenly in a molar ratio of (3-6)*Y:Y:(0.1-0.9)*Y, where Y is 1. Then, 0.1 mol / L hydrochloric acid is added, and the mixture is reacted in a water bath at 25°C for 1.0 h to obtain a tetraethyl orthosilicate solution.

[0062] Butanol, hexane, and Span-80 were measured according to a molar ratio of (0.1-0.9)*X : X : (3-4)*X, where X is 1. The mixture was placed in a water bath at 30°C and heated for 0.5 h. After the reaction was complete, tetraethyl orthosilicate solution was added, and the reaction was continued in a water bath for another 1.0 h to obtain a water-oil mixture.

[0063] D102: 0.5 mol / L ammonia solution was slowly added dropwise to a continuously stirred water-oil mixture, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours of aging, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-heptane at a volume ratio of 1:5 were added to the aged gel, and the modification reaction was carried out at an oil bath temperature of 80℃ for 6.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a silica matting agent. The dried powder was placed in a calcining furnace and calcined at 550℃ for 4.0 hours in air at a heating rate of 5℃ / min to obtain the silica matting agent.

[0064] Comparative Example 2 This application provides a comparative example of a method for preparing a silica matting agent, the method comprising: D201: Red mud was mixed with 7.0 mol / L hydrochloric acid, heated to 100℃, and stirred continuously for 2.5 h to obtain a reaction mixture. After cooling the reaction mixture to room temperature, it was separated by suction filtration through a Buchner funnel to obtain a Si-containing solid.

[0065] D202: After grinding and pulverizing the Si-containing solid, the Si-containing solid was mixed with 70% sulfuric acid at a solid-liquid ratio of 1g:10mL and placed in an oil bath. The mixture was reacted at 110℃ for 2.0 h to obtain a reaction mixture. The reaction mixture was then separated by suction filtration through a Buchner funnel to obtain a solid.

[0066] D203: A solid was mixed with a 4.0 mol / L sodium hydroxide solution at a solid-liquid ratio of 1 g: 30 mL and reacted in an oil bath at 110 °C for 3.0 h to obtain a reaction mixture. The reaction mixture was then centrifuged to obtain a sodium silicate solution.

[0067] D204: Measure n-butanol, n-heptane, and Span-80 according to the molar ratio (0.1-0.9)*X : X : (3-4)*X, where X is 1. Heat the mixture in a water bath at 30℃ for 0.5 h. After the reaction is complete, add sodium silicate solution and continue the reaction in the water bath for another 0.5 h to obtain a water-oil mixture.

[0068] D205: 5.0 mol / L hydrochloric acid was slowly added dropwise to a water-oil mixture under constant stirring, resulting in a slow gelation reaction and the formation of a gel. The resulting gel was allowed to stand for 6 hours of aging, then aged with ethanol for 6 hours, followed by aging with TEOS and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. TMCS and n-hexane at a volume ratio of 1:5 were added to the aged gel, and the mixture was modified at an oil bath temperature of 80℃ for 6.0 hours. The modified gel was placed in an oven and dried at 80℃ for 2 hours, then heated to 100℃ and dried for another 2 hours to obtain a silica matting agent. The dried powder was placed in a calcining furnace and calcined at 550℃ for 4.0 hours in air at a heating rate of 5℃ / min to obtain the silica matting agent.

[0069] The silica matting agents prepared in Examples 1 and 6 were subjected to XRD, hydrophilic contact angle, and lipophilic contact angle measurements, respectively, to obtain the results. Figure 1-6 .

[0070] From the appendix Figure 1 , 4 It is evident that the silica matting agents prepared using red mud and tetraethyl orthosilicate solution as silicon sources all exhibit silica spectral peaks, indicating that the product obtained after water-oil mixing, gelation, aging, modification, and calcination is silica.

[0071] From the appendix Figure 2 , 5 As can be seen, the silica matting agent prepared in Example 1 using tetraethyl orthosilicate solution as the silicon source exhibits excellent hydrophilicity, with a contact angle of almost 0°; while the silica matting agent prepared in Example 6 using sodium silicate solution extracted from red mud as the silicon source exhibits good hydrophobicity, with a contact angle of 135°.

[0072] From the appendix Figure 3 , 6 As can be seen, the silica matting agent prepared in Example 1 using tetraethyl orthosilicate solution as the silicon source and the silica matting agent prepared in Example 6 using sodium silicate solution extracted from red mud as the silicon source both exhibit excellent oleophilicity, and their contact angles are almost 0°.

[0073] In addition, the embodiments of this application also tested the specific surface area, pore volume, and oil absorption value of Examples 1 and 6, and Comparative Examples 1 and 2. The specific surface area and pore volume were tested using the BET specific surface area method, and the test results are shown in Table 1 and Table 2. Figure 7-10 As shown.

[0074] The specific process for detecting oil absorption value is as follows: A certain mass of silica matting agent was weighed and dried in an oven at 100ºC for 3.0 h to remove absorbed moisture. At room temperature, 1 g of the dried silica matting agent was accurately weighed and placed on a clean, dry glass plate. A dropping bottle containing dibutyl phthalate (DBP) was weighed and its mass recorded. DBP was added dropwise to the surface of the silica matting agent using a dropper, stirring with a glass rod while adding the DBP until the silica matting agent absorbed the moisture and became transparent with no obvious oil droplets remaining. This indicated the titration was complete. The mass of the dropping bottle containing DBP was then weighed again. The entire titration process should be completed within 10-15 minutes. The mass difference before and after titration was calculated and denoted as M. DBP The unit is g. The oil absorption value is calculated based on the density of dibutyl phthalate using the following formula: , where V DBP The oil absorption value (g / 100g) of silica matting agent, M DBP ρ is the mass difference (g) of dibutyl phthalate before and after dibutyl phthalate production, and ρ is the density of dibutyl phthalate.

[0075] Table 1: Physicochemical properties of the silica matting agents prepared in Examples 1-8 and Comparative Examples 9 and 10 From Table 1 and Appendix Figure 7-10 As can be seen, compared with Comparative Examples 1 and 2 which use different surfactants, the silica matting agents prepared in Examples 1 and 6 have larger pore volumes and higher oil absorption values, which indicates that the silica matting agents prepared in Examples 1 and 6 of this application all have good oleophilicity.

[0076] In summary, compared with other technical methods, the silica matting agent prepared by mixing aqueous and oil phases under a certain raw material ratio in this application has the water and oil phases complementing each other, which makes it oleophilic when forming a gel. Furthermore, the addition of surfactants in the subsequent step gives it a higher specific surface area and a higher oil absorption value. Moreover, the preparation method is simple and easy to operate.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a silica matting agent using red mud or tetraethyl orthosilicate as a silicon source, characterized in that, include: Alcohols, alkanes, and surfactants in a molar ratio of (0.1-0.9)*X : X : (3-4)*X are mixed and reacted in a water bath at 10-30℃ for 0.5-2.0 h; after adding a silicon source solution, the reaction is continued in a water bath for another 0.5-2.0 h to obtain a water-oil mixture; wherein X is 0.5-1.5, and the silicon source solution is a sodium silicate solution or tetraethyl orthosilicate solution extracted from red mud; The gelling agent is slowly added dropwise to the water-oil mixture while it is being stirred, and a gelation reaction occurs to form a gel. After the gel was allowed to stand for 6 hours, it was aged with ethanol for 6 hours, then aged with a solution of tetraethyl orthosilicate and ethanol at a volume ratio of 1:3 for 6 hours, and finally aged with n-heptane and ethanol at a volume ratio of 1:3 for 6 hours. Add trimethylchlorosilane and n-heptane in a volume ratio of 1:5 or trimethylchlorosilane and n-hexane in a volume ratio of 1:5 to the aged gel, modify it at 60-100℃ for 2-8 hours, and then dry and calcine at 400-600℃ for 1.0-6.0 hours to obtain a silica matting agent. Wherein, when the silicon source solution is a sodium silicate solution, the gelling agent is hydrochloric acid; when the silicon source solution is a tetraethyl orthosilicate solution, the gelling agent is ammonia or sodium hydroxide. The surfactant includes any one or more of ethylenediaminetetraacetic acid, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, lauryl glucoside, and disodium ethylenediaminetetraacetic acid.

2. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 1, characterized in that, Methods for extracting sodium silicate from red mud include: After red mud is mixed and reacted with hydrochloric acid with a concentration of 5.0-12.0 mol / L, the mixture is filtered to obtain a solid containing Si. The Si-containing solid was ground and pulverized, then reacted with acid in an oil bath, cooled, and filtered to obtain a solid. The solid reacts with sodium hydroxide solution in an oil bath, and after cooling and centrifugation, a sodium silicate solution is obtained.

3. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 2, characterized in that, The Si-containing solid is mixed with an acid with a concentration of 70-95% at a solid-liquid ratio of 1g:10mL, and the oil bath reaction temperature is 90-130℃ for 0.5-4.0h.

4. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 2, characterized in that, The solid is mixed with a sodium hydroxide solution with a concentration of 2.0-7.0 mol / L at a solid-liquid ratio of 1 g: 30 mL, and the reaction is carried out in an oil bath at a temperature of 90-130℃ for 0.5-4.0 h.

5. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 1, characterized in that, The preparation method of the tetraethyl orthosilicate solution includes: mixing tetraethyl orthosilicate, ethanol and deionized water in a molar ratio of (3-6)*Y:Y: (0.1-0.9)*Y, adding hydrochloric acid and reacting in a water bath to obtain the tetraethyl orthosilicate solution; wherein Y is 0.5-1.

5.

6. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 5, characterized in that, The concentration of hydrochloric acid is 0.1-1.0 mol / L, the water bath reaction temperature is 15-55℃, and the reaction time is 0.5-4.0 h.

7. The method for preparing silica matting agent using red mud or tetraethyl orthosilicate as a silicon source according to claim 1, characterized in that, The alcohols include n-butanol or glycerol; the alkanes include n-heptane or n-hexane.

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