Preparation method and application of nano calcium hydroxide liquid sol

Abstract

This invention belongs to the field of environmental protection materials technology and discloses a method for preparing and applying nano-calcium hydroxide sol. The preparation method includes the following steps: (1) mixing an alcohol with a solvent to obtain a molecularly induced mixture; (2) mixing micron-sized calcium oxide powder with the molecularly induced mixture to obtain a mixed slurry, and generating micro-nano bubbles in the mixed slurry using an ultrasonic micro-nano bubble generator, and then stirring to obtain a calcium hydroxide slurry; (3) adding a surfactant to the calcium hydroxide slurry, stirring, grinding, and obtaining nano-calcium hydroxide sol. This invention proposes a synergistic process of molecularly induced mixture and micro-nano bubbles to industrially prepare nano-calcium hydroxide sol. The nano-calcium hydroxide sol has good dispersibility and stability, can control the particle size of Ca(OH)2, reduce wastewater treatment costs, and reduce sludge production.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection materials technology, and specifically relates to a method for preparing and applying nano-calcium hydroxide sol. Background Technology

[0002] Calcium hydroxide, a moderately strong alkali with the chemical formula Ca(OH)₂, is widely used in various fields including chemistry, environmental protection, medicine, food, industry, and agriculture. In environmental protection, calcium hydroxide is commonly used to treat acidic wastewater. It not only neutralizes acidic wastewater but also captures metal ions, removes fluoride ions, accelerates precipitation, promotes sludge dewatering, sterilizes, and promotes the hydrolysis of organic matter. Calcium hydroxide can also be used for flue gas desulfurization, neutralizing sulfur dioxide, sulfur trioxide, and small amounts of fluoride and chloride ions, ensuring that the sulfur content of emitted flue gas meets environmental standards. In recent years, calcium hydroxide has also played an important role in green and low-carbon development as a carbon dioxide capture material.

[0003] Currently, in the fields of environmental protection and green low-carbon technologies, most calcium hydroxide is typically produced using the traditional digestion method, which involves directly mixing calcium oxide and water to obtain calcium hydroxide powder through a digestion reaction. While the traditional digestion method is simple and low-cost, the resulting calcium hydroxide particles are large and have poor uniformity. In wastewater treatment, flue gas desulfurization, and carbon dioxide capture, their small specific surface area and low activity lead to high consumption and poor application results, resulting in high overall costs. Particularly in acidic wastewater treatment, the large particle size of calcium hydroxide leads to incomplete reaction, increasing sludge production and further raising sludge treatment costs. Furthermore, in practical applications, to avoid dust and environmental pollution, calcium hydroxide suspensions (lime slurry) are often used for environmental remediation. This places higher demands on the dispersibility of calcium hydroxide particles; otherwise, large agglomerates will form, affecting reactivity.

[0004] Existing technology CN112174179A discloses an industrial preparation method for highly reactive nano-calcium hydroxide powder. This method first involves calcining limestone impregnated with a conditioning solution at a specific temperature to produce highly reactive quicklime with low impurity content. The quicklime is then crushed after impurity removal via a drum screen to obtain calcium oxide particles. These particles are then subjected to secondary digestion and air classification to obtain nano-calcium hydroxide powder. While this method can prepare nano-calcium hydroxide by controlling the reaction pressure and solid-liquid ratio, the process is lengthy, requires high-quality raw materials, and has a high overall cost. Existing technology CN112960684A discloses a preparation method for nano-calcium hydroxide powder used to accelerate flue gas desulfurization. This method uses a chemical precipitation method with calcium chloride and sodium hydroxide as raw materials, obtaining nano-calcium hydroxide by controlling the reaction conditions. Although this method can prepare nano-calcium hydroxide relatively well, its high raw material cost, poor process economy, and lack of operability make it difficult to achieve technology transfer and promotion in large-scale production.

[0005] Therefore, there is an urgent need to provide a new method for preparing nano-calcium hydroxide, which simplifies the production process and improves production efficiency. Summary of the Invention

[0006] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing nano-calcium hydroxide sol and its application. The preparation method of this invention simplifies the production process of nano-calcium hydroxide sol, can control the Ca(OH)₂ particle size, effectively increases the reaction rate of active substances, improves the reaction completeness, thereby reducing the amount of reagents used, lowering wastewater treatment costs, and reducing sludge production. Furthermore, the prepared nano-calcium hydroxide sol exhibits good dispersibility and stability.

[0007] This invention proposes a process for preparing nano-calcium hydroxide sol using a molecularly induced mixture and a micro / nano bubble synergistic process. This process enables the industrial-scale preparation of nano-calcium hydroxide sol, and the prepared nano-calcium hydroxide sol exhibits good dispersibility and stability. It can control the Ca(OH)2 particle size, effectively increase the reaction rate of active substances, improve the reaction completeness, thereby reducing the amount of reagents used, lowering wastewater treatment costs, and reducing sludge production.

[0008] The first aspect of the present invention provides a method for preparing nano-calcium hydroxide sol.

[0009] Specifically, a method for preparing a nano-calcium hydroxide sol includes the following steps:

[0010] (1) Mix alcohols with solvents to obtain molecularly induced mixtures;

[0011] (2) Take micron-sized calcium oxide powder and mix it with the molecularly induced mixture to obtain a mixed slurry. Use an ultrasonic micro-nano bubble generator to generate micro-nano bubbles in the mixed slurry. After stirring, obtain calcium hydroxide slurry.

[0012] (3) Add a surfactant to the calcium hydroxide slurry, stir, grind, and obtain the nano calcium hydroxide sol.

[0013] Preferably, in step (1), the alcohol is selected from at least one of polyvinyl alcohol and polyols.

[0014] More preferably, the polyol includes at least one of polyethylene glycol, glycerol, and triethanolamine.

[0015] Preferably, in step (1), the solvent includes water, and more preferably, the solvent is deionized water.

[0016] Preferably, in step (1), the ratio of the alcohol to the solvent is 0.003 to 0.1:1, more preferably 0.003 to 0.05:1.

[0017] Preferably, in step (1), the alcohol and solvent are mixed at a temperature of 40 to 60°C.

[0018] Preferably, in step (2), micron-sized calcium oxide powder is added to the molecularly induced mixture for mixing, and the stirring speed during mixing is 500–2800 r / min, more preferably 500–2500 r / min. Further, the stirring time during mixing is 2–5 h.

[0019] Preferably, in step (2), the micron-sized calcium oxide powder is added in multiple batches, for example, in 3 to 5 batches.

[0020] Preferably, in step (2), the mass ratio of the micron-sized calcium oxide powder to the molecularly induced mixture is 0.1 to 0.45:1, more preferably 0.2 to 0.35:1.

[0021] Preferably, in step (2), the particle size of the micron-sized calcium oxide powder is less than 10 μm, for example, 1-8 μm.

[0022] Preferably, in step (2), the mass fraction of the micron-sized calcium oxide powder is greater than 99%, which is high-purity micron-sized calcium oxide powder. Using high-purity ultrafine calcium oxide as raw material can increase the reactivity of the calcium oxide digestion reaction, enhance the uniformity of the reaction, and increase the contact between the reaction products and the molecularly induced mixture, playing a key role in controlling crystal growth.

[0023] Preferably, in step (2), the stirring speed is 500-1500 r / min and the stirring time is 1-3 h.

[0024] Preferably, in step (2), the stirring is performed using a double-planet stirring device.

[0025] Preferably, in step (3), the surfactant is selected from at least one of sodium dodecylbenzyl sulfonate, hexadecyltrimethylammonium bromide, octylphenyl polyoxyethylene ether, and polyvinylpyrrolidone.

[0026] Preferably, in step (3), the mass ratio of the surfactant to the calcium hydroxide slurry is 0.01 to 0.3:1, more preferably 0.02 to 0.06:1.

[0027] Preferably, in step (3), the stirring speed is 500-1500 r / min and the stirring time is 1-3 h.

[0028] Preferably, in step (3), the grinding involves transferring the calcium hydroxide slurry obtained after stirring into a ball mill jar and preparing nano-calcium hydroxide sol by ball milling.

[0029] Preferably, during the grinding process, the large grinding balls have a diameter of 12-16 mm, the medium grinding balls have a diameter of 6-8 mm, the small grinding balls have a diameter of 1-3 mm, the weight ratio of large, medium and small grinding balls is 1:(2-4):(5-7), the ball-to-material ratio is 2-5:1, and the grinding time is 2-5 hours.

[0030] Preferably, after grinding, the resulting mixture is passed through a 300-500 mesh sieve to obtain nano-calcium hydroxide sol.

[0031] Preferably, the preparation method includes the following steps:

[0032] (1) Using high-purity micron-sized calcium oxide powder as raw material;

[0033] (2) Add one or more of polyvinyl alcohol, polyethylene glycol, glycerol, triethanolamine, etc. to deionized water at a mass ratio of 0.003 to 0.05:1. After stirring evenly, a molecularly induced mixture is obtained. During the stirring process, a constant temperature device is used to heat the deionized water and control the temperature at 40 to 60°C.

[0034] (3) Under high-speed stirring conditions, the high-purity micron-sized calcium oxide powder prepared is added to the molecularly induced mixture to obtain a mixed slurry. The high-purity micron-sized calcium oxide powder is added in 3 to 5 portions. The mass ratio of the high-purity micron-sized calcium oxide powder to the molecularly induced mixture is 0.2 to 0.35:1. The stirring speed is 500 to 2500 r / min and the stirring time is 2 to 5 h. During the stirring process, micro-nano bubbles are generated in the mixed slurry by an ultrasonic micro-nano bubble generator. After stirring, calcium hydroxide slurry is obtained.

[0035] (4) Add one or more of sodium dodecylbenzyl sulfonate, hexadecyltrimethylammonium bromide, octylphenyl polyoxyethylene ether, and polyvinylpyrrolidone to the calcium hydroxide slurry in a mass ratio of 0.02 to 0.06:1, with a stirring speed of 500 to 1500 r / min and a stirring time of 1 to 3 h.

[0036] (5) Transfer the calcium hydroxide slurry obtained by stirring in step (4) to a ball mill jar and prepare nano calcium hydroxide liquid sol by ball milling. The diameter of the large ball is 12-16 mm, the diameter of the medium ball is 6-8 mm, the diameter of the small ball is 1-3 mm, the ratio of large, medium and small balls is 1:2-4:5-7, the ball-to-material ratio is 2-5:1, the ball milling time is 2-5 h, and the ball milled calcium hydroxide slurry is passed through a 300-500 mesh sieve to obtain nano calcium hydroxide liquid sol.

[0037] According to the digestion reaction theory, the initial temperature rise stage of the CaO digestion reaction mainly involves the reaction of CaO with water to form amorphous Ca(OH)2. As the reaction proceeds, the amorphous Ca(OH)2 crystals dissolve and release Ca. 2+ and OH - At this stage, the ion concentration and supersaturation in the solution reach their maximum, and the reaction is controlled by crystallization. As the reaction temperature decreases, the system mainly consists of dissolved Ca(OH)₂ and Ca²⁺. 2+ and OH - The process of crystallization and growth on Ca(OH)₂ nuclei in the liquid phase is controlled by ion diffusion. Therefore, to obtain Ca(OH)₂ products with smaller particle sizes, it is necessary to prepare a molecularly inducible mixture capable of controlling the growth of Ca(OH)₂ crystals. By adding compounds containing hydroxyl groups (-OH), chemical anchors can be formed on the surface of Ca(OH)₂ crystals during growth, thereby forming a molecular coating layer that induces crystal growth, thus controlling the growth of Ca(OH)₂ crystals and ultimately generating nano-Ca(OH)₂ particles. Furthermore, the addition of the molecularly inducible mixture can also reduce the surface energy of the crystals and prevent agglomeration. Thus, unlike other existing technologies, this approach emphasizes first preparing the molecularly inducible mixture and then adding CaO to it to achieve controlled crystal growth.

[0038] Furthermore, thermodynamic and kinetic analysis of the digestion reaction reveals that the initial temperature significantly impacts the digestion process. Different digestion temperatures provide varying initial energy for the calcium oxide digestion system. According to chemical reaction kinetics, higher digestion temperatures result in a larger reaction rate constant, increased product diffusion rate, and a faster digestion rate, allowing the system to reach its maximum temperature more quickly. Conversely, lower initial digestion temperatures fail to provide sufficient energy for the reaction, hindering its full progress. As the initial digestion temperature increases, the digestion rate accelerates, leading to a higher amount of calcium hydroxide produced per unit time. This increased calcium hydroxide concentration makes it easier for the liquid phase system to reach supersaturation, promoting crystal nucleation and the formation of small-sized, high-surface-area calcium hydroxide crystals. However, excessively high initial digestion temperatures can cause significant evaporation of digestion water, increasing the viscosity of the digestion system and hindering the diffusion and transfer of substances during the digestion process. Therefore, a suitable initial digestion temperature is crucial.

[0039] Controlling the digestion reaction conditions is a key factor in the preparation of nano-Ca(OH)₂ sol. Traditional preparation processes typically employ stirring or ultrasonic conditions. While traditional stirring is technically mature and cost-effective, it is difficult to achieve uniform dispersion of the reaction system, which is detrimental to the preparation of nano-Ca(OH)₂. In contrast, ultrasonic dispersion can induce molecular particle vibration and has better system dispersion capabilities, but it is expensive and has a short equipment lifespan. Therefore, this invention innovatively integrates double-star stirring with micro / nano bubble technology. This not only better leverages the advantages of stirring dispersion but also promotes the uniformity of the reaction system through the high-energy rupture effect of micro / nano bubbles. Furthermore, due to the dramatic change caused by the disappearance of the gas-liquid interface, the high concentration of ions accumulated at the interface releases the accumulated chemical energy, which can generate a large number of hydroxyl radicals and form chemical bond anchors, controlling the growth of Ca(OH)₂ crystals and thus more favorablely promoting the preparation of nano-Ca(OH)₂.

[0040] To reduce the viscosity of nano-Ca(OH)₂ sol, a suitable surfactant is added to the system to lower the surface tension, reduce intermolecular forces, and improve the system's fluidity. This approach proposes adding an appropriate surfactant to improve the system's properties after the product production and uniform dispersion are complete.

[0041] Ball milling is a key step in preparing nano-Ca(OH)₂ liquid sol. It involves increasing the defect density on the particle surface and gradually refining the grains through frequent collisions between the grinding balls, grinding jar, and particles under external mechanical force. To prepare uniform and high-quality nano-Ca(OH)₂ liquid sol, this invention proposes further processing the prepared nano-Ca(OH)₂ liquid sol using ball milling, while carefully controlling the grinding ball ratio and ball-to-particle ratio to ensure the final preparation of a high-performance nano-Ca(OH)₂ liquid sol.

[0042] A second aspect of the present invention provides a nano-calcium hydroxide sol.

[0043] A nano-calcium hydroxide sol was prepared by the above-described method.

[0044] The third aspect of the present invention provides the application of a method for preparing nano-calcium hydroxide sol.

[0045] The above-mentioned method for preparing nano-calcium hydroxide sol has been applied in wastewater treatment.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] This invention proposes a process for preparing nano-calcium hydroxide sol using a molecularly induced mixture and a micro / nano bubble synergistic process. This process enables the industrial-scale preparation of nano-calcium hydroxide sol, and the prepared nano-calcium hydroxide sol exhibits good dispersibility and stability. It can control the Ca(OH)2 particle size, effectively increase the reaction rate of active substances, improve the reaction completeness, thereby reducing the amount of reagents used, lowering wastewater treatment costs, and reducing sludge production. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the process flow for preparing nano-calcium hydroxide sol in Example 3;

[0049] Figure 2 This is a microscopic morphology diagram of the nano-calcium hydroxide sol in Example 3. Detailed Implementation

[0050] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0051] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0052] The micro-nano bubble generator was provided by Foshan Qianye Guangsheng Environmental Protection Technology Co., Ltd., model number MNB-05.

[0053] Example 1: Preparation of nano-calcium hydroxide sol

[0054] A method for preparing nano-calcium hydroxide sol includes the following steps:

[0055] (1) Weigh 1g of polyvinyl alcohol and add it to 1L of deionized water under stirring. Stir at a constant temperature for 30min to prepare a molecularly induced mixture. The stirring temperature is 50℃.

[0056] (2) Turn on the ultrasonic micro-nano bubble generator (power of 500W, flow rate of 1000L / h) to form micro-nano bubbles in the molecularly induced mixture. Under stirring conditions, weigh 200g of micron-sized calcium oxide powder (the particle size of micron-sized calcium oxide powder is 3-5μm, and the mass fraction is greater than 99%) and add it to the molecularly induced mixture in three portions. Stir (double star stirring device) at a speed of 1500r / min for 2h to obtain calcium hydroxide slurry.

[0057] (3) Then weigh 20g of sodium dodecylbenzenesulfonate and add it to the calcium hydroxide slurry, stirring for 1 hour;

[0058] (4) After stirring in step (3), transfer the prepared calcium hydroxide slurry to a ball mill jar, add 3 kg of grinding balls, select large balls with a diameter of 16 mm, medium balls with a diameter of 8 mm, and small balls with a diameter of 2 mm, the ratio of large, medium and small balls is 1:3:6, and the ball milling time is 2 h.

[0059] (5) After ball milling in step (4), the prepared slurry is passed through a 300-mesh sieve to obtain nano-calcium hydroxide sol.

[0060] Example 2: Preparation of nano-calcium hydroxide sol

[0061] A method for preparing nano-calcium hydroxide sol includes the following steps:

[0062] (1) Weigh 0.5 g of glycerol and add it to 1 L of deionized water under stirring. Stir at a constant temperature for 30 min to prepare a molecularly induced mixture. The stirring temperature is 60 °C.

[0063] (2) Turn on the ultrasonic micro-nano bubble generator (power of 500W, flow rate of 1000L / h) to form micro-nano bubbles in the molecularly induced mixture. Under stirring conditions, weigh 200g of micron-sized calcium oxide powder (the particle size of micron-sized calcium oxide powder is 3-5μm, and the mass fraction is greater than 99%) and add it to the molecularly induced mixture in three portions. Stir (double star stirring device) at a speed of 1000r / min for 4h to obtain calcium hydroxide slurry.

[0064] (3) Then weigh 30g of cetyltrimethylammonium bromide and add it to the calcium hydroxide slurry, stirring for 2 hours;

[0065] (4) After stirring in step (3), transfer the prepared calcium hydroxide slurry to a ball mill jar, add 2 kg of grinding balls, select large balls with a diameter of 12 mm, medium balls with a diameter of 6 mm, and small balls with a diameter of 1 mm, the ratio of large, medium and small balls is 1:2:7, and the ball milling time is 3 h.

[0066] (5) After ball milling in step (4), the prepared slurry is passed through a 400-mesh sieve to obtain nano-calcium hydroxide sol.

[0067] Example 3: Preparation of nano-calcium hydroxide sol

[0068] A method for preparing nano-calcium hydroxide sol includes the following steps:

[0069] (1) Weigh 10g of polyethylene glycol and add it to 1L of deionized water under stirring. Stir at a constant temperature for 30min to prepare a molecularly induced mixture. The stirring temperature is 50℃.

[0070] (2) Turn on the ultrasonic micro-nano bubble generator (power of 500W, flow rate of 1000L / h) to form micro-nano bubbles in the molecularly induced mixture. Under stirring conditions, weigh 200g of micron-sized calcium oxide powder (the particle size of micron-sized calcium oxide powder is 3-5μm, and the mass fraction is greater than 99%) and add it to the molecularly induced mixture in three portions. Stir (double star stirring device) at a speed of 2000r / min for 5h to obtain calcium hydroxide slurry.

[0071] (3) Then weigh 25g of polyvinylpyrrolidone (surfactant) and add it to the calcium hydroxide slurry, and stir for 1 hour;

[0072] (4) After stirring in step (3), the prepared calcium hydroxide slurry is transferred to a ball mill jar, and 5 kg of grinding balls are added. The large ball diameter is 14 mm, the medium ball diameter is 6 mm, and the small ball diameter is 2 mm. The ratio of large, medium and small balls is 1:4:5, and the ball milling time is 4 h.

[0073] (5) After ball milling in step (4), the prepared slurry is passed through a 300-mesh sieve to obtain nano-calcium hydroxide sol.

[0074] Figure 1 This is a schematic diagram of the process flow for preparing nano-calcium hydroxide sol in Example 3.

[0075] Figure 2 This is a microscopic morphology image of the nano-sized calcium hydroxide sol in Example 3. From... Figure 2It can be seen that the nano-calcium hydroxide sol prepared in Example 3 has a small particle size and uniform particle size.

[0076] Comparative Example 1

[0077] Weigh 200g of calcium oxide and add it to 1L of deionized water under stirring conditions. The stirring speed is 1500r / min and the stirring time is 2h to prepare a calcium hydroxide suspension.

[0078] Product effectiveness test

[0079] (1) Settlement volume ratio.

[0080] Take 100 mL each of the products (calcium hydroxide suspension and nano-calcium hydroxide sol) prepared in Comparative Example 1, Example 1, Example 2, and Example 3, place them in a stoppered graduated cylinder, shake up and down for 5 min, and let stand at room temperature for 24 h. Calculate their sedimentation volume ratio F. The specific calculation formula is as follows:

[0081] F = V / V0 = H / H0;

[0082] In the formula: V0 and H0 are the initial measured volume and height of the product, respectively; V and H are the volume and height of the sediment after standing for 24 hours, respectively.

[0083] (2) Acidic wastewater treatment and sludge quantity testing.

[0084] Take 40g each of the products prepared in Comparative Example 1, Example 1, Example 2, and Example 3, and transfer them to a beaker. Then, add 60mL of deionized water to the beaker to prepare a diluted reagent. Measure 200mL of Ni-containing... 2+ Wastewater was placed in a beaker, and the prepared reagent was slowly added in a measured amount under magnetic stirring. A comparative experiment was conducted, and the pH of the acidic wastewater was adjusted to 11. The treated wastewater was allowed to stand for 45 minutes, and then filtered using a circulating water vacuum pump, Buchner funnel, and qualitative filter paper to separate sludge. The sludge mass was calculated using the difference method.

[0085] The test results obtained after the above sedimentation volume test, acidic wastewater treatment and sludge quantity test are shown in Table 1.

[0086] Table 1: Comparison of Performance Test Results of Various Examples and Comparative Examples

[0087] Example 1 1 <![CDATA[12.3kg / m 3 ]]> <![CDATA[1.16kg / m 3 ]]> Example 2 1 <![CDATA[12.2kg / m 3 ]]> <![CDATA[1.14kg / m 3 ]]> Example 3 1 <![CDATA[12.0kg / m 3 ]]> <![CDATA[1.12kg / m 3 ]]> Comparative Example 1 0.7 <![CDATA[14.5kg / m 3 ]]> <![CDATA[1.52kg / m 3 ]]>

[0088] As shown in Table 1, Examples 1-3 all have high sedimentation volume ratios. A higher sedimentation volume ratio indicates that the prepared product has good dispersibility and stability, and also indirectly reflects that the calcium hydroxide particles in the examples are small. In contrast, Comparative Example 1 has a sedimentation volume ratio of 0.7, which indicates that the calcium hydroxide particles in this product are larger and easier to settle.

[0089] Furthermore, analysis of Table 1 shows that Examples 1-3, in the case of acidic Ni-containing... 2+ In wastewater treatment, the calculated dosage for pH adjustment is 12.0-12.3 kg / m³. 3 The dry-basis sludge volume generated from wastewater is calculated to be 1.12-1.16 kg / m³. 3 In comparison, the pH adjustment dosage for Comparative Example 1 was 14.5 kg / m³. 3 The dry sludge volume is calculated to be 1.52 kg / m³. 3 This result fully demonstrates that the preparation of the nano-calcium hydroxide sol of the present invention can control the particle size of Ca(OH)2, effectively increase the reaction rate of active substances, improve the reaction completeness, thereby reducing the amount of reagents used, reducing wastewater treatment costs, and reducing sludge production.

[0090] For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of this invention, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention.

Claims

1. A method for preparing a nano-calcium hydroxide liquid sol, characterized in that, Includes the following steps: (1) Mix alcohols with solvents to obtain molecularly induced mixtures; (2) Take micron-sized calcium oxide powder and mix it with the molecularly induced mixture to obtain a mixed slurry. Use an ultrasonic micro / nano bubble generator to generate micro / nano bubbles in the mixed slurry. After stirring, obtain calcium hydroxide slurry. The mass ratio of the micron-sized calcium oxide powder to the molecularly induced mixture is 0.1~0.45:

1. (3) Add surfactant to the calcium hydroxide slurry, stir, grind, and obtain the nano calcium hydroxide sol.

2. The production method according to claim 1, characterized by, In step (1), the alcohol is selected from at least one of polyvinyl alcohol and polyols.

3. The production method according to claim 1, characterized by, In step (1), the ratio of the alcohol to the solvent is 0.003 to 0.1:

1.

4. The method of claim 1, wherein, In step (2), micron-sized calcium oxide powder is added to the molecularly induced mixture for mixing. The stirring speed during mixing is 500~2800 r / min, and the micron-sized calcium oxide powder is added in multiple batches.

5. The preparation method according to claim 1, characterized in that, In step (2), the particle size of the micron-sized calcium oxide powder is less than 10 μm; and / or, the mass fraction of the micron-sized calcium oxide powder is greater than 99%; and / or, in step (2), the stirring is carried out using a double-star stirring device.

6. The method of claim 1, wherein, In step (3), the surfactant is selected from at least one of sodium dodecylbenzyl sulfonate, hexadecyltrimethylammonium bromide, octylphenyl polyoxyethylene ether, and polyvinylpyrrolidone; and / or, in step (3), the mass ratio of the surfactant to the calcium hydroxide slurry is 0.01 to 0.3:

1.

7. The preparation method according to claim 1, characterized in that, In step (3), the grinding involves transferring the calcium hydroxide slurry obtained after stirring into a ball mill jar and preparing nano-calcium hydroxide sol by ball milling.

8. A nano-calcium hydroxide sol, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the preparation method according to any one of claims 1-7 in wastewater treatment.

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