Nanometer material-based adsorption type fluorine removal agent and preparation method thereof

Abstract

This invention relates to the field of defluorination agent technology, specifically to an adsorption-type defluorination agent based on nanomaterials and its preparation method. The adsorption-type defluorination agent based on nanomaterials provided by this invention comprises the following raw materials in parts by weight: 9-15 parts nano-alumina; 15-25 parts inorganic acid; 2-5 parts cationic surfactant; and 60-70 parts water. By adding a cationic surfactant (e.g., one or a mixture of dimethyl diallyl ammonium chloride and dimethylaminoethyl methacrylate) and an inorganic acid to the alumina defluorination agent, this invention can improve the adsorption and flocculation capacity of alumina, thus economically and effectively overcoming the shortcomings of insufficient fluoride removal rates in traditional defluorination agents.

Description

Technical Field

[0001] This invention relates to the field of defluorination technology, specifically to an adsorption-type defluorination agent based on nanomaterials and its preparation method. Background Technology

[0002] Fluorides are a relatively difficult pollutant to treat in industrial wastewater, especially those from industries such as semiconductors, photovoltaics, metallurgy, and phosphate fertilizers. Improper treatment can have an impact on the environment and human health.

[0003] Current treatment processes include chemical precipitation, coagulation sedimentation, adsorption, and membrane separation. Chemical precipitation involves adding defluoridating agents to a sedimentation tank to remove fluoride from wastewater. Traditional defluoridating agents struggle to reduce fluoride levels below 1.5 mg / L at low cost; adsorption methods are expensive and require regeneration of the packing material; membrane separation technology has high investment costs and suffers from difficulties in treating concentrated wastewater.

[0004] Therefore, there is an urgent need to develop a new adsorption-type defluorinating agent to improve the removal rate of fluorides in wastewater. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an adsorption-type defluorinating agent based on nanomaterials and its preparation method. This invention adds a cationic surfactant (e.g., one or a mixture of dimethyl diallyl ammonium chloride or dimethyl aminoethyl methacrylate) and an inorganic acid to the alumina defluorinating agent, which can improve the adsorption and flocculation capacity of alumina and improve the shortcomings of insufficient fluoride removal rate of traditional defluorinating agents in terms of economy and effectiveness.

[0006] Therefore, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides, in optional embodiments, an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials in parts by weight: 9-15 parts nano-alumina; 15-25 parts inorganic acid; 2-5 parts cationic surfactant; and 60-70 parts water. It can be further selected that: 10-12.5 parts nano-alumina; 18-21 parts inorganic acid; 2-5 parts cationic surfactant; and 64.5-67 parts water.

[0008] This invention adds cationic surfactants (e.g., one or a mixture of dimethyl diallyl ammonium chloride or dimethyl aminoethyl methacrylate) and inorganic acids to alumina defluorinating agents, which can improve the adsorption and flocculation capabilities of alumina and improve the shortcomings of traditional defluorinating agents in terms of insufficient fluoride removal rate in terms of economy and effectiveness.

[0009] In this invention, a positively charged adsorption layer (-N) is formed on the surface of nano-alumina particles by electrostatic adsorption and chemical bonding (hydroxyl condensation) using a cationic surfactant. + (CH3)3 groups) enhance the electrostatic capture and coordination adsorption of fluoride ions. Additionally, the addition of inorganic acids promotes protonation of the nano-alumina surface (Al-OH2). + This further enhances the chemical adsorption capacity for fluoride ions (forming Al-F coordination bonds).

[0010] Preferably, the cationic surfactant is selected from one or a mixture of dimethyl diallyl ammonium chloride and dimethylaminoethyl methacrylate; and / or, the particle size of the nano-alumina is 20-80 nm. The inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, or nitric acid; and / or, the concentration of the inorganic acid is 10-15%.

[0011] Furthermore, the adsorbent-type defluorinating agent also includes 0.5-1 parts of a dispersant. The dispersant is selected from one or more of sodium polyacrylate, polyvinyl alcohol, or polyethylene glycol.

[0012] Secondly, in an optional embodiment, the present invention provides a method for preparing the above-mentioned adsorption-type defluorination agent based on nanomaterials, comprising the following steps:

[0013] Nano-alumina, cationic surfactant, dispersant and water are mixed and then ultrasonically treated. Inorganic acid is added dropwise to adjust the pH value. Finally, the mixture is heated and stirred to obtain an adsorption-type defluorination agent.

[0014] Preferably, the ultrasonic treatment temperature is 60-70℃; and / or, the ultrasonic treatment time is 20-40 min. The pH value is 3-5. The heating and stirring temperature is 75-85℃; and / or, the heating and stirring time is 60-90 min. The stirring and mixing time is 8-12 min; and / or, the stirring and mixing speed is 200-300 rpm.

[0015] In this invention, a staged heating process (first pre-reacting at 60-70℃ for 20-40 min, then heating to 75-85℃ and stirring for 60-90 min) ensures that the surfactant first rapidly adheres to the nano-alumina surface through physical adsorption, and then high temperature promotes chemical bonding (such as ester or amide bond formation) to form a stable modified layer. Ultrasonic waves (frequency 20-40 kHz, power 100-300 W) are introduced at the initial stage of the reaction to break up nanoparticle aggregates using cavitation, promoting uniform coating of the surfactant and forming a stable dispersion system with a narrow particle size distribution. This further improves the grafting rate of the cationic surfactant and enhances the adsorption capacity of the defluorinating agent.

[0016] Compared with the prior art, the present invention has one of the following beneficial effects:

[0017] 1. The present invention adds cationic surfactants (e.g., one or a mixture of dimethyl diallyl ammonium chloride or dimethyl aminoethyl methacrylate) and inorganic acids to the alumina defluorinating agent, which can improve the adsorption and flocculation capacity of alumina and improve the shortcomings of insufficient fluoride removal rate of traditional defluorinating agents in terms of economy and effectiveness.

[0018] 2. By adding cationic surfactants, a positively charged adsorption layer (-N) is formed on the surface of nano-alumina particles through electrostatic adsorption and chemical bonding (hydroxyl condensation). + (CH3)3 groups) enhance the electrostatic capture and coordination adsorption of fluoride ions. Additionally, the addition of inorganic acids promotes protonation of the nano-alumina surface (Al-OH2). + This further enhances the chemical adsorption capacity for fluoride ions (forming Al-F coordination bonds).

[0019] 3. This invention employs a staged heating process (first a pre-reaction at 60-70℃ for 20-40 min, then stirring at 75-85℃ for 60-90 min) to ensure that the surfactant first rapidly adheres to the nano-alumina surface through physical adsorption, and then high temperature promotes chemical bonding (such as ester or amide bond formation) to form a stable modified layer. In the initial stage of the reaction (the first 30 minutes), ultrasound (frequency 20-40 kHz, power 100-300 W) is introduced to break up nanoparticle aggregates using cavitation, promoting uniform coating of the surfactant and forming a stable dispersion system with a narrow particle size distribution. This further improves the grafting rate of the cationic surfactant and enhances the adsorption capacity of the defluorinating agent. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] In the following examples and comparative examples, the average particle size of the nano-alumina was 50 nm, and the dimethyl diallyl ammonium chloride, dimethylaminoethyl methacrylate, and polyethylene glycol (average molecular weight 4000) were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0022] The technical solution of the present invention will be described below with reference to the embodiments. Example

[0023] This embodiment provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0024] 11 kg of nano-alumina, 20 kg of 10% hydrochloric acid, 3 kg of dimethyl diallyl ammonium chloride, and 65 kg of water.

[0025] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0026] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride and water according to the formula ratio.

[0027] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0028] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0029] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent. Example

[0030] This embodiment provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0031] 11 kg of nano-alumina, 20 kg of 10% hydrochloric acid, 3 kg of dimethylaminoethyl methacrylate and 65 kg of water.

[0032] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0033] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethylaminoethyl methacrylate and water according to the formula ratio.

[0034] Step 2: Add nano-alumina, dimethylaminoethyl methacrylate and water to the reaction vessel, turn on mechanical stirring (250 rpm), and mix for 10 minutes until initially dispersed;

[0035] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0036] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethylaminoethyl methacrylate and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent. Example

[0037] This embodiment provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0038] 11 kg of nano-alumina, 20 kg of sulfuric acid with a mass concentration of 10%, 3 kg of dimethyl diallyl ammonium chloride, and 65 kg of water.

[0039] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0040] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride and water according to the formula ratio.

[0041] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0042] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0043] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent. Example

[0044] This embodiment provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0045] 11 kg of nano-alumina, 20 kg of nitric acid with a mass concentration of 10%, 3 kg of dimethyl diallyl ammonium chloride, and 65 kg of water.

[0046] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0047] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride and water according to the formula ratio.

[0048] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0049] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0050] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent. Example

[0051] This embodiment provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0052] 11 kg nano alumina, 20 kg hydrochloric acid with a mass concentration of 10%, 3 kg dimethyl diallyl ammonium chloride, 0.8 kg polyethylene glycol, and 65 kg water.

[0053] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0054] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride, polyethylene glycol, and water according to the formula ratio.

[0055] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride, polyethylene glycol and water to the reactor, turn on mechanical stirring (250 rpm), and mix for 10 minutes until initially dispersed;

[0056] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0057] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent.

[0058] Comparative Example 1

[0059] This comparative example provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0060] 11 kg of nano-alumina, 20 kg of hydrochloric acid with a mass concentration of 10% and 65 kg of water.

[0061] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0062] Step 1: Weigh out nano-alumina, hydrochloric acid, and water according to the formula ratio.

[0063] Step 2: Add nano-alumina and water to the reactor, turn on mechanical stirring (250 rpm), and mix for 10 minutes until initially dispersed;

[0064] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4.

[0065] Step 4: Turn off the ultrasonic generator, heat to 75°C, stir at a constant temperature for 80 minutes, and finally cool to room temperature to obtain the defluorinating agent.

[0066] Comparative Example 2

[0067] This comparative example provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0068] 11 kg of nano-alumina, 3 kg of dimethyl diallyl ammonium chloride and 65 kg of water.

[0069] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0070] Step 1: Weigh out nano-alumina, dimethyl diallyl ammonium chloride, and water according to the formula ratio.

[0071] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0072] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes.

[0073] Step 4: Turn off the ultrasonic generator, heat to 75°C, and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent.

[0074] Comparative Example 3

[0075] This comparative example provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0076] 11 kg of nano-alumina and 65 kg of water.

[0077] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0078] Step 1: Weigh out nano-alumina and water according to the formula ratio.

[0079] Step 2: Add nano-alumina and water to the reaction vessel, turn on mechanical stirring (250 rpm), mix for 10 minutes to obtain the defluorinating agent.

[0080] Comparative Example 4

[0081] This comparative example provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0082] 11 kg of nano-alumina, 20 kg of 10% hydrochloric acid, 3 kg of dimethyl diallyl ammonium chloride, and 65 kg of water.

[0083] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0084] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride and water according to the formula ratio.

[0085] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0086] Step 3: Add hydrochloric acid dropwise to the mixture after initial dispersion in Step 2 to adjust the pH of the system to 4.

[0087] Step 4: Heat to 75℃ and stir at a constant temperature for 80 minutes to allow dimethyl diallyl ammonium chloride and nano-alumina to fully chemically bond. Finally, cool to room temperature to obtain the defluorinating agent.

[0088] Comparative Example 5

[0089] This comparative example provides an adsorption-type defluorinating agent based on nanomaterials, comprising the following raw materials:

[0090] 11 kg of nano-alumina, 20 kg of 10% hydrochloric acid, 3 kg of dimethyl diallyl ammonium chloride, and 65 kg of water.

[0091] The preparation method of the above-mentioned adsorption-type defluorinating agent based on nanomaterials includes the following steps:

[0092] Step 1: Weigh out nano-alumina, hydrochloric acid, dimethyl diallyl ammonium chloride and water according to the formula ratio.

[0093] Step 2: Add nano-alumina, dimethyl diallyl ammonium chloride and water to the reaction vessel, turn on mechanical stirring (speed is 250 rpm), and mix for 10 minutes until initially dispersed;

[0094] Step 3: Add the mixture after preliminary dispersion in Step 2 to the ultrasonic generator, turn on the ultrasonic generator, and ultrasonically treat it at 65°C for 30 minutes. At the same time, add hydrochloric acid to adjust the pH of the system to 4. Finally, turn off the ultrasonic generator and cool it to room temperature to obtain the defluorinating agent.

[0095] Experimental Example

[0096] The defluorination effects of the defluorinating agents prepared in Examples 1-6 and Comparative Examples 1-5 were tested. Taking the defluorination effect in wastewater (mainly semiconductor wastewater) from a centralized industrial wastewater treatment plant in Guangzhou as an example, the dosage of the defluorinating agent was 1496 ppm. The defluorination effects are shown in Table 1.

[0097] Table 1. Fluoride removal efficiency of wastewater in a centralized industrial wastewater treatment plant in Guangzhou.

[0098] Fluoride content in raw water (mg / L) Fluorine content after treatment (mg / L) Defluorination efficiency (%) Example 1 8.221 1.957 76.19 Example 2 7.173 1.947 72.85 Example 3 6.712 2.051 69.44 Example 4 7.161 2.181 69.54 Example 5 6.105 1.217 80.07 Comparative Example 1 6.523 3.500 46.35 Comparative Example 2 6.105 3.200 47.58 Comparative Example 3 6.125 4.515 26.29 Comparative Example 4 5.898 2.856 51.58 Comparative Example 5 6.195 2.973 52.01

[0099] Conclusion: Comparison of data from Examples 1 and 6 shows that adding a dispersant to the defluorinating agent formulation can improve the defluorination effect. Comparison of data from Example 1 and Comparative Examples 1-3 shows that the addition of a cationic surfactant enables the electrostatic adsorption and chemical bonding (hydroxyl condensation) of a positively charged adsorption layer (-N) on the surface of the nano-alumina particles. + (CH3)3 groups) enhance the electrostatic capture and coordination adsorption of fluoride ions. Additionally, the addition of inorganic acids promotes protonation of the nano-alumina surface (Al-OH2). + This further enhances the chemical adsorption capacity for fluoride ions (forming Al-F coordination bonds). Comparing the data from Example 1 and Comparative Examples 4-5 shows that by staged heating (first pre-reacting at 60-70℃ for 20-40 min, then raising to 75-85℃ and stirring for 60-90 min), the surfactant is ensured to first rapidly adhere to the nano-alumina surface through physical adsorption, and then the high temperature promotes chemical bonding (such as the formation of ester or amide bonds), forming a stable modified layer. Introducing ultrasound at the initial stage of the reaction utilizes the cavitation effect to break up nanoparticle aggregates, promoting uniform coating of the surfactant and forming a stable dispersion system with a narrow particle size distribution. This further improves the grafting rate of the cationic surfactant and increases the adsorption capacity of the defluorinating agent.

[0100] Although the principles of the present invention have been described in detail above with reference to preferred embodiments, those skilled in the art should understand that the above embodiments are merely illustrative explanations of the implementation of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Any obvious changes, such as equivalent transformations or simple substitutions, based on the technical solutions of the present invention without departing from the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A nanomaterial-based adsorptive fluorine removal agent, characterized in that, The adsorption type defluorination agent comprises the following raw materials by weight: 9-15 parts of nano-alumina; 15-25 parts of inorganic acid; 2-5 parts of cationic surfactant; and 60-70 parts of water. The adsorption type defluorination agent further comprises 0.5-1 part of dispersant selected from one or more of sodium polyacrylate, polyvinyl alcohol or polyethylene glycol; The cationic surfactant is selected from one or mixture of dimethyl diallyl ammonium chloride or dimethylaminoethyl methacrylate; The nano-alumina, cationic surfactant, dispersant and water are stirred and mixed, then ultrasonic treatment is performed, inorganic acid is added dropwise to adjust the pH value to 3-5, and finally temperature stirring is performed to obtain the adsorption type defluorination agent.

2. The adsorption type defluorination agent based on nano-material according to claim 1, wherein, The particle size of the nano-alumina is 20-80 nm.

3. The nanomaterial-based adsorptive fluorine removal agent according to claim 1, characterized by, The inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid or nitric acid; and / or, The concentration of the inorganic acid is 10-15%.

4. A method for preparing the nanomaterial-based adsorptive fluorine removal agent according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: The nano-alumina, cationic surfactant, dispersant and water are stirred and mixed, then ultrasonic treatment is performed, inorganic acid is added dropwise to adjust the pH value to 3-5, and finally temperature stirring is performed to obtain the adsorption type defluorination agent.

5. The preparation method of the adsorption-type defluorinating agent based on nanomaterials according to claim 4, characterized in that, The temperature of the ultrasonic treatment is 60-70℃; and / or, The time of the ultrasonic treatment is 20-40 min.

6. The preparation method of the adsorption-type defluorinating agent based on nanomaterials according to claim 4, characterized in that, The temperature of the temperature stirring is 75-85℃; and / or, The time of the temperature stirring is 60-90 min.

7. The preparation method of the adsorption-type defluorinating agent based on nanomaterials according to claim 4, characterized in that, The time of the stirring and mixing is 8-12 min; and / or, The rotating speed of the stirring and mixing is 200-300 rpm.