Nanoscale environment-friendly calcium hydroxide and preparation process thereof

Abstract

The invention provides nanoscale environment-friendly calcium hydroxide and a preparation process thereof, and belongs to the field of inorganic materials. The KH570 silane coupling agent is used for modifying anhydrous calcium chloride, so that the interaction force among calcium chloride particles is weakened, the calcium chloride particles are more easily dispersed in a solution, and the generation of nano calcium hydroxide is facilitated. Ca (OH) 2 powder is grafted and modified through polyacrylic acid, the charge property of the surface of calcium hydroxide is changed, and the anticoagulation capacity of calcium hydroxide is improved. Secondly, microcapsules are prepared through a complex coacervation method, the Ca (OH) 2 powder is subjected to coating treatment, and the anticoagulation capacity of the Ca (OH) 2 powder obtained after microencapsulation is further improved.

Description

Technical Field

[0001] The invention belongs to the field of inorganic materials and relates to a preparation process of anti-coagulation calcium hydroxide, in particular to a nano-level environmentally friendly calcium hydroxide and a preparation process thereof. Background Art

[0002] Nano anti-coagulation calcium hydroxide, as a product of the cross-integration of nanotechnology and traditional materials science, is gradually showing its unique advantages and wide application potential. This material is prepared through a special process and has nano-scale particle size and anti-coagulation properties, which gives it a series of excellent physical and chemical properties. In terms of application, the performance of nano anti-coagulation calcium hydroxide is particularly outstanding. In the field of environmental protection, as an efficient desulfurization agent and wastewater treatment agent, it can significantly reduce the content of pollutants in the atmosphere and water bodies, and contribute to the cause of environmental protection. At the same time, in the building materials industry, nano anti-coagulation calcium hydroxide is also a key raw material for the preparation of high-performance concrete and new wall materials. These materials not only have higher strength and durability, but also can effectively save energy and resources. In addition, nano anti-coagulation calcium hydroxide also shows broad application prospects in agriculture, food, medicine and new energy. In the agricultural field, it can be used to improve soil, increase soil fertility and crop yields; in the food industry, it can be used as a food additive to improve the taste and quality of food; in the pharmaceutical field, it can be used as a drug excipient to improve the stability and bioavailability of drugs; and in the development of new energy, nano anti-coagulation calcium hydroxide provides new solutions for hydrogen energy storage, carbon dioxide capture and storage, etc. In summary, as a high-performance material, nano anti-coagulation calcium hydroxide is leading the development trend of materials science with its unique advantages and broad application prospects. In the future, improving the anti-coagulation ability of nano calcium hydroxide will become the focus of researchers. Summary of the invention

[0003] In view of the above problems, the present invention designs a preparation process of nano-scale environmentally friendly calcium hydroxide; the process specifically comprises the following steps: S1. Weigh 1.8-2.4g KH570 silane coupling agent and dissolve it in 70-100mL deionized water and 7-10mL anhydrous ethanol solution. Stir until the solution is completely dissolved and then add 0.08-0.14mol acetic acid solution to adjust the pH of the solution to 4.5.

[0004] S2, weigh 18-24g of anhydrous CaCl2 and refine it in a high-pressure homogenizer for 2-5h, pour the refined powder into the mixed solution with adjusted pH in S1, then add 3.5-8g of surfactant hydroxysulfopropyl betaine to the solution, stir for 40-70min to mix it evenly. The modification of silane coupling agent weakens the interaction between calcium chloride particles, making it easier to disperse in the solution.

[0005] S3, weigh 5-11g NaOH and dissolve it in 10-40ml deionized water and add the NaOH solution into the S2 mixed solution which is stirred at a constant speed (500 r / min) through a constant pressure dropping funnel. Stop stirring after the NaOH solution is dripped off and place it at room temperature for 30min. Wash the solid obtained by filtration several times with anhydrous ethanol and then freeze-dry it to obtain Ca(OH)2 powder. S4, polyacrylic acid grafted modified Ca(OH)2 powder: weigh 1.2-4.2g polyacrylic acid and 0.1-0.4g ammonium superphosphate and dissolve them in 10-25ml deionized water and record it as solution A. Add the Ca(OH)2 powder prepared in S3 and 40-70ml deionized water into a three-necked flask and stir to mix evenly, and adjust the pH of the mixed solution to 8-9 with 0.2-0.5mol NaOH solution. After the adjustment, place the three-necked flask in a constant temperature water bath and heat it to 60-90℃. Slowly add solution A while stirring and react for 2-5h, stirring continuously during the reaction. After the reaction, collect the Ca(OH)2 powder by centrifugation and wash it three times with deionized water, and dry it in a 60℃ oven for 4-8h to obtain the polyacrylic acid grafted modified Ca(OH)2 powder. The carboxyl groups in polyacrylic acid react chemically with the hydroxyl groups on the surface of calcium hydroxide to form chemical bonds, thereby grafting polyacrylic acid onto the surface of calcium hydroxide. This grafting modification changes the charge properties of the surface of calcium hydroxide and improves the anti-coagulation ability of calcium hydroxide.

[0006] S5, Ca(OH)2 microencapsulation preparation: weigh 4.5-6g gelatin and 3.5-5g carboxymethyl cellulose (CMC) and pour them into two 100ml beakers respectively, add 50ml deionized water to each, and then heat them in a 30-60℃ water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them into a 200ml beaker together and stir them evenly with a glass rod, add 4g Ca(OH)2 powder prepared in S4 to the stirred solution, and then use a high-speed tissue crusher to emulsify and homogenize at a speed of 12000r / min for 2-6min to form an emulsion; after the mixed emulsion is quickly poured into a 200ml straight three-necked flask, place it in a constant temperature water bath at 400 r / min and a constant temperature of 30-60°C, and the emulsion pH is adjusted to 4.4-4.8 with a 7-10% glacial acetic acid solution, and then stirred for 15-30 minutes; after stirring, the emulsion is cooled to below 15°C with an ice water bath, and then the pH value of the emulsion is adjusted to neutral with a 10-16% KOH solution by mass, and then 2.2-3.7g of glutamine aminotransferase (TG) is added and stirred at 400r / min for 4-6h to fully solidify the microcapsules produced by the polymerization; the solidified The completed microcapsule dispersion is allowed to stand for 10-12 hours, the supernatant is poured off, the solids are collected and washed three times with deionized water, the washing liquid containing the solids is poured onto filter paper and filtered to obtain wet microcapsules, which are then dried in a vacuum freeze dryer for 2 hours to obtain Ca(OH)2 powder microcapsule products; the composite coacervation method is used to prepare microcapsules in this step, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties.

[0007] Preferably, the amount of KH570 silane coupling agent used in step S1 is 2 g; Preferably, the amount of hydroxysulfopropyl betaine used in step S2 is 5 g; Preferably, the amount of NaOH used in step S3 is 7 g; Preferably, the amount of polyacrylic acid used in step S4 is 2.2 g; Preferably, the temperature of the constant temperature water bath in step S4 is 90°C; Preferably, in step S4, solution A is slowly added while stirring and reacted for 4 hours; Preferably, 4.5 g of carboxymethyl cellulose is added in step S5; Preferably, in step S5, stirring is performed at a constant temperature of 50° C.; Compared with the prior art, the present invention has the following beneficial effects: The use of KH570 silane coupling agent to modify anhydrous calcium chloride weakens the interaction between calcium chloride particles, making it easier to disperse in the solution, which is beneficial to the formation of nano calcium hydroxide.

[0008] The present invention adds polyacrylic acid, and the carboxyl groups in the polyacrylic acid react chemically with the hydroxyl groups on the surface of the calcium hydroxide to form chemical bonds so that the polyacrylic acid is grafted onto the surface of the calcium hydroxide. This grafting modification changes the charge properties of the surface of the calcium hydroxide and improves the anti-coagulation ability of the calcium hydroxide.

[0009] The present invention prepares nano calcium hydroxide microcapsules by using a composite coagulation method, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a bar graph showing the viscosity test of microencapsulated nano calcium hydroxide prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention.

[0011] Figure 2 This is a bar graph of the water absorption rate of microencapsulated nano calcium hydroxide prepared in Example 3, Comparative Example 7 and Comparative Example 8 of the present invention.

[0012] Figure 3 This is an electron scanning microscope image of the microencapsulated nano calcium hydroxide prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0013] Exemplary embodiments, features and performance aspects of the present invention will be described in detail below with reference to the accompanying drawings.

[0014] Example 1

[0015] S1. Weigh 1.8 g KH570 silane coupling agent and dissolve it in 70 mL deionized water and 7 mL anhydrous ethanol solution. Stir until the solution is completely dissolved and then add 0.08 mol acetic acid solution to adjust the pH of the solution to 4.5.

[0016] S2, weigh 18g of anhydrous CaCl2 and refine it in a high-pressure homogenizer for 2h, pour the refined powder into the mixed solution with adjusted pH in S1, then add 3.5g of surfactant hydroxysulfopropyl betaine to the solution, stir for 40min to mix it evenly. The modification of silane coupling agent weakens the interaction between calcium chloride particles, making it easier to disperse in the solution.

[0017] S3, weigh 5g NaOH and dissolve it in 10ml deionized water and add the NaOH solution into the S2 mixed solution which is stirred at a constant speed (500 r / min) through a constant pressure dropping funnel. Stop stirring after the NaOH solution is dripped off and place it at room temperature for 30min. Wash the solid obtained by filtration several times with anhydrous ethanol and freeze-dry it to obtain Ca(OH)2 powder. S4, polyacrylic acid grafted modified Ca(OH)2 powder: weigh 1.2g polyacrylic acid and 0.1g ammonium superphosphate and dissolve them in 10ml deionized water and record it as solution A. Add the Ca(OH)2 powder prepared in S3 and 40ml deionized water into a three-necked flask and stir and mix evenly. Use 0.2mol NaOH solution to adjust the pH of the mixed solution to 8. After the adjustment, put the three-necked flask into a constant temperature water bath and heat it to 60℃. Add solution A slowly while stirring and react for 2h, and stir continuously during the reaction. After the reaction, collect the Ca(OH)2 powder by centrifugation and wash it three times with deionized water. Dry it in an oven at 60℃ for 4h to obtain the Ca(OH)2 powder grafted modified by polyacrylic acid. The carboxyl group in polyacrylic acid reacts chemically with the hydroxyl group on the surface of calcium hydroxide to form a chemical bond so that polyacrylic acid is grafted onto the surface of calcium hydroxide. This grafting modification changes the charge properties of the surface of calcium hydroxide and improves the anti-coagulation ability of calcium hydroxide. .

[0018] S5, Ca(OH)2 microencapsulation preparation: weigh 5g gelatin and 4g carboxymethyl cellulose (CMC) and pour them into two 100ml beakers respectively, add 50ml deionized water to each, and then heat in a 30℃ water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them into a 200ml beaker together and stir evenly with a glass rod, add 4g Ca(OH)2 powder prepared in S4 to the stirred solution, and then use a high-speed tissue crusher to emulsify and homogenize at a speed of 12000r / min for 2min to form an emulsion; quickly pour the mixed emulsion into a 200ml straight three-necked flask, place it in a constant temperature water bath at 400 r / min and 30 ℃ constant temperature conditions, while stirring, the emulsion pH is adjusted to 4.4 with 7% glacial acetic acid solution, and then stirred for 15 minutes; after stirring, the emulsion is cooled to below 15 ℃ in an ice water bath, and then the pH value of the emulsion is adjusted to neutral with a 10% mass fraction KOH solution, and then 2.2g of glutamine aminotransferase (TG) is added and stirred at 400r / min for 4 hours to fully solidify the microcapsules produced by the polymerization; the solidified microcapsule dispersion is allowed to stand for 10 hours, the supernatant is poured off, the solids are collected and washed three times with deionized water, the washing liquid containing the solids is poured on filter paper and filtered to obtain wet microcapsules, and then dried in a vacuum freeze dryer for 2 hours to obtain Ca(OH)2 powder microcapsule products; the composite coacervation method is used to prepare microcapsules in this step, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties.

[0019] Comparative Example 1: Except that KH570 silane coupling agent is not added in step S1, the remaining steps are the same as those in Example 1.

[0020] Comparative Example 2: Except that high-pressure homogenizer is not used for refinement in step S1, the other steps are the same as those in Example 1.

[0021] Comparative Example 3: Except that acetic acid solution is not added in step S1, the other steps are the same as those in Example 1.

[0022] The microencapsulated nano calcium hydroxide prepared by the invention and liquid paraffin are uniformly mixed in a beaker at a mass ratio of 1:2, and the viscosity of the mixed system at room temperature is measured by a rotary viscometer. Figure 1The viscosity test of the microencapsulated nano calcium hydroxide prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 of the present invention shows that the viscosity of the sample of Comparative Example 1 without adding KH570 silane coupling agent is significantly higher than that of other samples, which is mainly due to the fact that the KH570 silane coupling agent weakens the interaction between the calcium chloride particles, making it easier to disperse in the solution. Comparative Example 2 shows that the refinement of anhydrous calcium chloride is helpful for improving the viscosity of the sample, because the anhydrous calcium chloride particles after refinement are smaller and the digestion reaction is more complete. Not adding acetic acid is not conducive to the hydrolysis of the KH570 silane coupling agent, thereby reducing its dispersibility.

[0023] Example 2

[0024] S1. Weigh 2 g of KH570 silane coupling agent and dissolve it in 80 mL of deionized water and 8 mL of anhydrous ethanol solution. Stir until the solution is completely dissolved and then add 0.1 mol of acetic acid solution to adjust the pH of the solution to 4.5.

[0025] S2, weigh 20g of anhydrous CaCl2 and refine it in a high-pressure homogenizer for 3h, pour the refined powder into the mixed solution with adjusted pH in S1, then add 5g of surfactant hydroxysulfopropyl betaine to the solution, stir for 50min to mix it evenly. The modification of silane coupling agent weakens the interaction between calcium chloride particles, making it easier to disperse in the solution.

[0026] S3, weigh 7g NaOH and dissolve it in 20ml deionized water and add the NaOH solution into the S2 mixed solution which is stirred at a constant speed (500 r / min) through a constant pressure dropping funnel. Stop stirring after the NaOH solution is dripped off and place it at room temperature for 30min. Wash the solid obtained by filtration several times with anhydrous ethanol and freeze-dry it to obtain Ca(OH)2 powder. S4, polyacrylic acid grafted modified Ca(OH)2 powder: weigh 2.2g polyacrylic acid and 0.2g ammonium superphosphate and dissolve them in 15ml deionized water and record it as solution A. Add the Ca(OH)2 powder prepared in S3 and 50ml deionized water into a three-necked flask and stir and mix evenly. Use 0.3mol NaOH solution to adjust the pH of the mixed solution to 8. After the adjustment, put the three-necked flask into a constant temperature water bath and heat it to 70℃. Add solution A slowly while stirring and react for 3h, and stir continuously during the reaction. After the reaction, collect the Ca(OH)2 powder by centrifugation and wash it three times with deionized water. Dry it in an oven at 60℃ for 5h to obtain the Ca(OH)2 powder grafted modified by polyacrylic acid. The carboxyl group in polyacrylic acid reacts chemically with the hydroxyl group on the surface of calcium hydroxide to form a chemical bond so that polyacrylic acid is grafted onto the surface of calcium hydroxide. This grafting modification changes the charge properties of the surface of calcium hydroxide and improves the anti-coagulation ability of calcium hydroxide. .

[0027] S5, Ca(OH)2 microencapsulation preparation: weigh 5.5g gelatin and 4.5g carboxymethyl cellulose (CMC) and pour them into two 100ml beakers respectively, add 50ml deionized water to each, and then heat in a 50℃ water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them into a 200ml beaker together and stir evenly with a glass rod, add the Ca(OH)2 powder prepared in S4 to the stirred solution, and then use a high-speed tissue crusher to emulsify and homogenize at a speed of 12000r / min for 3min to form an emulsion; quickly pour the mixed emulsion into a 200ml straight three-necked flask, place it in a constant temperature water bath at 400 r / min and a constant temperature of 40°C, while stirring, the pH value of the emulsion is adjusted to 4.4 with 8% glacial acetic acid solution, and then stirred for 20 minutes; after stirring, the emulsion is cooled to below 15°C with an ice-water bath, and then the pH value of the emulsion is adjusted to neutral with a 12% mass fraction KOH solution, and then 2.7g of glutamine aminotransferase (TG) is added and stirred at 400r / min for 5 hours to fully solidify the microcapsules produced by the polymerization; the solidified microcapsule dispersion is allowed to stand for 11 hours, the supernatant is poured off, the solids are collected and washed three times with deionized water, the washing liquid containing the solids is poured on filter paper and filtered to obtain wet microcapsules, and then dried in a vacuum freeze dryer for 2 hours to obtain Ca(OH)2 powder microcapsule products; the composite coacervation method is used to prepare microcapsules in this step, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties.

[0028] Comparative Example 4: Except that polyacrylic acid is not added in step S4, the other steps are the same as those in Example 2.

[0029] Comparative Example 5: Except for replacing polyacrylic acid with polypropylene in step S4, the remaining steps are the same as those in Example 2.

[0030] Comparative Example 6: Except for using acetic acid instead of polyacrylic acid in step S4, the remaining steps are the same as those in Example 2.

[0031] 2 g of each of the microencapsulated nano calcium hydroxide prepared in Example 2, Comparative Example 4, Comparative Example 5 and Comparative Example 6 were placed in an oven at 105° C. and allowed to stand for 12 h. After standing, the samples were taken out and weighed.

[0032] Table 1 The data in Table 1 are all average values ​​from multiple experiments. It can be seen from the data in Table 1 that the calcium hydroxide powder modified by polyacrylic acid grafting has excellent anti-calcification ability, which also means that it has stronger anti-coagulation ability, which is mainly due to the fact that the carboxyl calcium group generated by grafting is not easy to react with carbon dioxide in the air. The samples of comparative examples 4, 5 and 6 absorb more carbon dioxide, which shows that the calcium hydroxide modified by polyacrylic acid has specificity.

[0033] Example 3

[0034] S1. Weigh 2.2 g of KH570 silane coupling agent and dissolve it in 90 mL of deionized water and 90 mL of anhydrous ethanol solution. Stir until the solution is completely dissolved and then add 0.12 mol of acetic acid solution to adjust the pH of the solution to 4.5.

[0035] S2, weigh 22g of anhydrous CaCl2 and refine it in a high-pressure homogenizer for 4h, pour the refined powder into the mixed solution with adjusted pH in S1, then add 6.5g of surfactant hydroxysulfopropyl betaine to the solution, stir for 60min to mix it evenly. The modification of silane coupling agent weakens the interaction between calcium chloride particles, making it easier to disperse in the solution.

[0036] S3, weigh 9g NaOH and dissolve it in 30ml deionized water and add the NaOH solution into the S2 mixed solution which is stirred at a constant speed (500 r / min) through a constant pressure dropping funnel. Stop stirring after the NaOH solution is dripped off and place it at room temperature for 30min. Wash the solid obtained by filtration several times with anhydrous ethanol and freeze-dry it to obtain Ca(OH)2 powder. S4, polyacrylic acid grafted modified Ca(OH)2 powder: weigh 3.2g polyacrylic acid and 0.3g ammonium superphosphate and dissolve them in 20ml deionized water and record it as solution A. Add the Ca(OH)2 powder prepared in S3 and 60ml deionized water into a three-necked flask and stir and mix evenly. Use 0.4mol NaOH solution to adjust the pH of the mixed solution to 9. After the adjustment, put the three-necked flask into a constant temperature water bath and heat it to 80℃. Add solution A slowly while stirring and react for 4h, and stir continuously during the reaction. After the reaction, collect the Ca(OH)2 powder by centrifugation and wash it three times with deionized water. Dry it in an oven at 60℃ for 7h to obtain the Ca(OH)2 powder grafted modified by polyacrylic acid. The carboxyl group in polyacrylic acid reacts chemically with the hydroxyl group on the surface of calcium hydroxide to form a chemical bond so that polyacrylic acid is grafted onto the surface of calcium hydroxide. This grafting modification changes the charge properties of the surface of calcium hydroxide and improves the anti-coagulation ability of calcium hydroxide. .

[0037] S5, Ca(OH)2 microencapsulation preparation: weigh 5.5g gelatin and 4.5g carboxymethyl cellulose (CMC) and pour them into two 100ml beakers respectively, add 50ml deionized water to each, and then heat them in a 50℃ water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them into a 200ml beaker together and stir them evenly with a glass rod, add 4g Ca(OH)2 powder prepared in S4 to the stirred solution, and then use a high-speed tissue crusher to emulsify and homogenize at a speed of 12000r / min for 5min to form an emulsion; quickly pour the mixed emulsion into a 200ml straight three-necked flask, place it in a constant temperature water bath at 400 r / min and 50 ℃ constant temperature conditions, while stirring, the emulsion pH is adjusted to 4.8 with 9% glacial acetic acid solution, and then stirred for 25 minutes; after stirring, the emulsion is cooled to below 15 ℃ in an ice water bath, and then the pH value of the emulsion is adjusted to neutral with a 14% mass fraction KOH solution, and then 3.2g of glutamine aminotransferase (TG) is added and stirred at 400r / min for 6 hours to fully solidify the microcapsules produced by the polymerization; the solidified microcapsule dispersion is allowed to stand for 12 hours, the supernatant is poured off, the solids are collected and washed three times with deionized water, the washing liquid containing the solids is poured on filter paper and filtered to obtain wet microcapsules, and then dried in a vacuum freeze dryer for 2 hours to obtain Ca(OH)2 powder microcapsule products; the composite coacervation method is used to prepare microcapsules in this step, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties.

[0038] Comparative Example 7: Except that gelatin is not added in step S5, the remaining steps are the same as those in Example 3.

[0039] Comparative Example 8: Except that glutamine aminotransferase is not added in step S5, the remaining steps are the same as those in Example 3.

[0040] Take 2 g of each of the microencapsulated nano calcium hydroxide prepared in Example 3, Comparative Example 7, and Comparative Example 8 and place them in a constant humidity and heat test box (humidity: 90%, temperature 20°C) and let them stand for 5 hours. Then weigh the mass of the samples after standing and measure the moisture absorption capacity of the samples.

[0041] Depend on Figure 2 It can be seen that the hygroscopic capacity of calcium hydroxide after microencapsulation in Example 3 is significantly lower than that of Comparative Examples 7 and 8, which is mainly due to the barrier of the microcapsules, which greatly weakens its hygroscopicity, but the low hygroscopicity indicates that it has excellent anti-coagulation ability. Comparative Example 7, which is not microencapsulated, has a high hygroscopicity rate due to the lack of protection of the microcapsules, so it is easy to coagulate. Comparative Example 8 does not add glutamine aminotransferase to solidify the microcapsules, so the formed microcapsules are easy to break, thereby exposing the internal calcium hydroxide particles, and are therefore easier to coagulate.

[0042] Example 4

[0043] S1. Weigh 2.4 g of KH570 silane coupling agent and dissolve it in 100 mL of deionized water and 10 mL of anhydrous ethanol solution. Stir until the solution is completely dissolved and then add 0.14 mol of acetic acid solution to adjust the pH of the solution to 4.5.

[0044] S2, weigh 24g of anhydrous CaCl2 and refine it in a high-pressure homogenizer for 5h, pour the refined powder into the mixed solution with adjusted pH in S1, then add 8g of surfactant hydroxysulfopropyl betaine to the solution, stir for 70min to mix it evenly. The modification of silane coupling agent weakens the interaction between calcium chloride particles, making it easier to disperse in the solution.

[0045] S3, weigh 11g NaOH and dissolve it in 40ml deionized water and add the NaOH solution into the S2 mixed solution which is stirred at a constant speed (500 r / min) through a constant pressure dropping funnel. Stop stirring after the NaOH solution is dripped off and place it at room temperature for 30min. Wash the solid obtained by filtration several times with anhydrous ethanol and freeze-dry it to obtain Ca(OH)2 powder. S4, polyacrylic acid grafted modified Ca(OH)2 powder: Weigh 4.2g polyacrylic acid and 0.4g ammonium superphosphate and dissolve them in 25ml deionized water and record them as solution A. Add the Ca(OH)2 powder prepared in S3 and 70ml deionized water into a three-necked flask and stir to mix evenly. Use 0.5mol NaOH solution to adjust the pH of the mixed solution to 9. After the adjustment, place the three-necked flask in a constant temperature water bath and heat it to 90℃. Add solution A slowly while stirring and react for 5h, and stir continuously during the reaction. After the reaction, collect the Ca(OH)2 powder by centrifugation and wash it three times with deionized water. Dry it in an oven at 60℃ for 8h to obtain the Ca(OH)2 powder grafted modified by polyacrylic acid. The carboxyl group in polyacrylic acid reacts chemically with the hydroxyl group on the surface of calcium hydroxide to form a chemical bond, so that polyacrylic acid is grafted onto the surface of calcium hydroxide. This grafting modification changes the charge properties of the surface of calcium hydroxide and improves the anti-coagulation ability of calcium hydroxide. .

[0046] S5, Ca(OH)2 microencapsulation preparation: weigh 6g gelatin and 5g carboxymethyl cellulose (CMC) and pour them into two 100ml beakers respectively, add 50ml deionized water to each, and then heat in a 60℃ water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them into a 200ml beaker together and stir evenly with a glass rod, add 4g Ca(OH)2 powder prepared in S4 to the stirred solution, and then use a high-speed tissue crusher to emulsify and homogenize at a speed of 12000r / min for 6min to form an emulsion; quickly pour the mixed emulsion into a 200ml straight three-necked flask, place it in a constant temperature water bath at 400 r / min and 60 ℃ constant temperature conditions, while stirring, the emulsion pH is adjusted to 4.8 with 10% glacial acetic acid solution, and then stirred for 30 minutes; after stirring, the emulsion is cooled to below 15 ℃ in an ice water bath, and then the pH value of the emulsion is adjusted to neutral with a 16% mass fraction KOH solution, and then 3.7g of glutamine aminotransferase (TG) is added and stirred at 400r / min for 6 hours to fully solidify the microcapsules produced by the polymerization; the solidified microcapsule dispersion is allowed to stand for 12 hours, the supernatant is poured off, the solids are collected and washed three times with deionized water, the washing liquid containing the solids is poured on filter paper and filtered to obtain wet microcapsules, and then dried in a vacuum freeze dryer for 2 hours to obtain Ca(OH)2 powder microcapsule products; the composite coacervation method is used to prepare microcapsules in this step, which has the advantages of mild conditions, low equipment requirements and simple operation compared with other microcapsule preparation methods, and the microcapsule products prepared by this method generally have excellent anti-coagulation properties.

[0047] Figure 3 The microencapsulated nano calcium hydroxide prepared in Example 4 of the present invention can be observed to be completely and evenly coated with the microcapsules. The coating of the microcapsules and the polyacrylic acid grafted modified calcium hydroxide together improve the anti-coagulation ability of calcium hydroxide.

[0048] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solution described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. A process for preparing nano-scale environmentally friendly calcium hydroxide, characterized in that: The invention discloses a polyacrylic acid grafted modified calcium hydroxide powder. The preparation method of the polyacrylic acid grafted modified calcium hydroxide powder is as follows: weigh polyacrylic acid and ammonium superphosphate, dissolve them in deionized water and record them as solution A; add the calcium hydroxide powder prepared in S3 and deionized water into a three-necked flask, stir and mix them evenly, and adjust the pH value of the mixed solution to 8-9 with a NaOH solution; after the adjustment, put the three-necked flask into a constant temperature water bath and heat it to 60-90°C; slowly add solution A to react while stirring, and continue stirring during the reaction; after the reaction, centrifuge and collect the calcium hydroxide powder, wash it three times with deionized water, and dry it in a 60°C oven for 4-8h to obtain the polyacrylic acid grafted modified calcium hydroxide powder.

2. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 1, characterized in that: The specific preparation method is as follows: S1. Weigh KH570 silane coupling agent and dissolve it in deionized water and anhydrous ethanol solution. Stir until the solution is completely dissolved and then add acid solution to adjust the pH of the solution to 4.

5. S2, weigh anhydrous CaCl2 and refine it in a high-pressure homogenizer, pour the refined powder into the mixed solution with pH adjusted in S1, then add surfactant hydroxysulfopropyl betaine to the solution, and stir to mix it evenly; S3, weighing NaOH and dissolving it in deionized water, adding the NaOH solution to the S2 mixed solution stirred at a constant speed through a constant pressure dropping funnel, stopping stirring after the NaOH solution is dripped off, leaving it at room temperature for 30 minutes, washing the solid obtained by suction filtration several times with anhydrous ethanol, and then freeze-drying it to obtain calcium hydroxide powder; S4, polyacrylic acid grafted modified calcium hydroxide powder: weigh polyacrylic acid and ammonium superphosphate, dissolve them in deionized water and record them as solution A; add the calcium hydroxide powder prepared in S3 and deionized water into a three-necked flask, stir and mix them evenly, and adjust the pH of the mixed solution to 8-9 with a NaOH solution; after the adjustment, put the three-necked flask into a constant temperature water bath and heat it to 60-90°C; slowly add solution A to react while stirring, and continue stirring during the reaction; after the reaction, centrifuge and collect the calcium hydroxide powder, wash it three times with deionized water, and dry it in a 60°C oven for 4-8h to obtain the polyacrylic acid grafted modified calcium hydroxide powder; S5. Preparation of calcium hydroxide microcapsules: Weigh gelatin and carboxymethyl cellulose, add water and heat in a 30-60°C water bath until fully dissolved; after the liquids in the two beakers cool to room temperature, pour them together and stir evenly with a glass rod, add the calcium hydroxide powder prepared in S4 to the stirred evenly solution, and then use a high-speed tissue pounder to emulsify and homogenize for 2-6 minutes to form an emulsion; after the mixed evenly emulsion is quickly poured into a container, it is placed in a constant temperature water bath and stirred at a constant temperature of 30-60°C, and the emulsion is adjusted with glacial acetic acid solution. H to 4.4-4.8, and then stirred for 15-30 minutes; after stirring, use an ice water bath to cool the emulsion to below 15°C, then adjust the pH value of the emulsion to neutral, then add glutamine aminotransferase and keep stirring to fully solidify the microcapsules produced by the polymerization; let the solidified microcapsule dispersion stand, pour the supernatant, collect the solids and wash them three times with deionized water, pour the water washing liquid containing solids on filter paper and filter to obtain wet microcapsules, and then dry them in a vacuum freeze dryer for 2 hours to obtain calcium hydroxide powder microcapsule products.

3. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: In step S1, 2 g of KH570 silane coupling agent is added.

4. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that In step S2, 5 g of hydroxysulfopropyl betaine is added.

5. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: In the step S3, 7 g of NaOH is added.

6. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: In the step S4, 2.2 g of polyacrylic acid is added.

7. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: The temperature of the constant temperature water bath in step S4 is 90°C.

8. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: In step S4, solution A is slowly added while stirring and reacted for 4 hours.

9. A process for preparing nano-scale environmentally friendly calcium hydroxide according to claim 2, characterized in that: In step S5, 4.5 g of carboxymethyl cellulose is added.

10. A nano-scale environmentally friendly calcium hydroxide prepared by the process for preparing a nano-scale environmentally friendly calcium hydroxide according to any one of claims 1 to 9.

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