Adsorption type fluorine removal agent based on nano material and preparation method of adsorption type fluorine removal agent

Abstract

The invention relates to the technical field of fluorine removal agents, in particular to an adsorption type fluorine removal agent based on a nanometer material and a preparation method of the adsorption type fluorine removal agent. The invention provides an adsorption type fluorine removal agent based on a nanometer material. The adsorption type fluorine removal agent comprises the following raw materials in parts by weight: 9-15 parts of nanometer aluminum oxide; 15-25 parts of inorganic acid; 2-5 parts of a cationic surface active agent; and 60-70 parts of water. The cationic surfactant (such as one or a mixture of two of dimethyl diallyl ammonium chloride or dimethylaminoethyl methacrylate) and the inorganic acid are added into the aluminum oxide fluorine removal agent, so that the adsorption and flocculation capacities of aluminum oxide can be improved, and the defect that the fluoride removal rate of a traditional fluorine removal agent is insufficient is overcome economically and effectively.

Description

Technical Field

[0001] The present invention relates to the technical field of defluoridation agents, and in particular to an adsorption-type defluoridation agent based on nanomaterials and a preparation method thereof. Background Art

[0002] Fluoride is a relatively difficult pollutant to treat in industrial wastewater, especially from the semiconductor, photovoltaic, metallurgical, phosphate fertilizer and other industries. Improper treatment will have an impact on the environment and human health.

[0003] Current treatment processes include chemical precipitation, coagulation-sedimentation, adsorption, and membrane separation. Chemical precipitation removes fluoride from wastewater by adding a defluoridation agent to a sedimentation tank. Traditional defluoridation agents struggle to cost-effectively reduce fluoride levels to below 1.5 mg / L. Adsorption is expensive and requires regeneration of the filler. Membrane separation technology, on the other hand, presents high investment costs and difficulty treating concentrated wastewater.

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

[0005] In order to solve the above technical problems, the present invention provides an adsorption-type defluoridant based on nanomaterials and a preparation method thereof. The present invention adds a cationic surfactant (for example, one of dimethyldiallylammonium chloride or dimethylaminoethyl methacrylate or a mixture of the two) and an inorganic acid to the alumina defluoridant, which can improve the adsorption and flocculation capabilities of alumina, thereby improving the disadvantage of insufficient fluoride removal rate of traditional defluoridants from the perspective of economy and effectiveness.

[0006] To this end, the present invention provides the following technical solutions: In a first aspect, the present invention provides, in an optional embodiment, a nanomaterial-based adsorption-type defluoridation agent 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. Further alternative compositions may include: 10-12.5 parts nano-alumina; 18-21 parts inorganic acid; 2-5 parts cationic surfactant; and 64.5-67 parts water.

[0007] The present invention adds a cationic surfactant (for example, one of dimethyldiallylammonium chloride and dimethylaminoethyl methacrylate or a mixture of the two) and an inorganic acid to the alumina defluoridant, thereby improving the adsorption and flocculation capabilities of the alumina and improving the disadvantage of the traditional defluoridant in terms of economy and effectiveness, that is, the insufficient fluoride removal rate.

[0008] In the present invention, a positively charged adsorption layer (-N+ (CH3)3 group), strengthen the electrostatic capture and coordination adsorption of fluoride ions, and in addition, promote the protonation of the nano-alumina surface by adding inorganic acid (Al-OH2 + ), further enhancing the chemical adsorption capacity of fluoride ions (forming Al-F coordination bonds).

[0009] Preferably, the cationic surfactant is selected from one or a mixture of dimethyldiallylammonium chloride or 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%.

[0010] Furthermore, the adsorption-type defluoridating agent further comprises 0.5-1 parts of a dispersant, which is selected from one or more of sodium polyacrylate, polyvinyl alcohol, or polyethylene glycol.

[0011] In a second aspect, the present invention provides, in an optional embodiment, a method for preparing the above-mentioned nanomaterial-based adsorption-type defluoridating agent, comprising the following steps: The nano-alumina, cationic surfactant, dispersant and water are stirred and mixed, then ultrasonically treated, and inorganic acid is added dropwise to adjust the pH value. Finally, the mixture is heated and stirred to obtain an adsorption-type defluoridating agent.

[0012] Preferably, the ultrasonic treatment temperature is 60-70°C; and / or the ultrasonic treatment duration is 20-40 minutes. The pH value is 3-5. The temperature of the heating and stirring is 75-85°C; and / or the heating and stirring duration is 60-90 minutes. The stirring and mixing duration is 8-12 minutes; and / or the stirring and mixing speed is 200-300 rpm.

[0013] In this invention, a staged temperature increase (pre-reaction at 60-70°C for 20-40 minutes, followed by stirring at 75-85°C for 60-90 minutes) ensures that the surfactant first rapidly adheres to the nano-alumina surface through physical adsorption. High temperature then promotes chemical bonding (such as ester or amide bond formation) to form a stable modified layer. Ultrasonic waves (frequency 20-40kHz, power 100-300W) are introduced at the initial stage of the reaction to break up nanoparticle agglomerates through cavitation, promoting uniform surfactant coating and forming a stable dispersion with a narrow particle size distribution. This further increases the grafting rate of the cationic surfactant and enhances the adsorption capacity of the defluoridating agent.

[0014] Compared with the prior art, the present invention has one of the following beneficial effects: 1. The present invention adds a cationic surfactant (for example, one of dimethyldiallylammonium chloride and dimethylaminoethyl methacrylate, or a mixture of the two) and an inorganic acid to the alumina defluoridant to improve the adsorption and flocculation capabilities of the alumina, thereby improving the disadvantage of insufficient fluoride removal rate of traditional defluoridants from the perspective of economy and effectiveness.

[0015] 2. Through the electrostatic adsorption and chemical bonding (hydroxyl condensation) of the cationic surfactant, a positively charged adsorption layer (-N + (CH3)3 group), strengthen the electrostatic capture and coordination adsorption of fluoride ions, and in addition, promote the protonation of the nano-alumina surface by adding inorganic acid (Al-OH2 + ), further enhancing the chemical adsorption capacity of fluoride ions (forming Al-F coordination bonds).

[0016] 3. This invention utilizes a staged temperature increase (pre-reaction at 60-70°C for 20-40 minutes, followed by heating to 75-85°C and stirring for 60-90 minutes) to ensure that the surfactant first rapidly adheres to the nano-alumina surface through physical adsorption. High temperature then 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 during the initial reaction phase (the first 30 minutes) to break up nanoparticle agglomerates through cavitation, promoting uniform surfactant coating and forming a stable dispersion with a narrow particle size distribution. This further increases the grafting rate of the cationic surfactant and enhances the adsorption capacity of the defluoridating agent. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] In the following examples and comparative examples, the average particle size of nano-alumina was 50 nm, and dimethyldiallylammonium chloride, dimethylaminoethyl methacrylate, and polyethylene glycol (average molecular weight 4000) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0019] The technical solution of the present invention will be described below with reference to embodiments. Example

[0020] This embodiment provides an adsorption-type defluorination agent based on nanomaterials, including the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride and 65kg water.

[0021] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride and water according to the formula ratio.

[0022] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0023] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent. Example

[0024] This embodiment provides an adsorption-type defluorination agent based on nanomaterials, including the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10%, 3kg dimethylaminoethyl methacrylate and 65kg water.

[0025] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethylaminoethyl methacrylate and water according to the formula ratio.

[0026] Step 2: Add nano-alumina, dimethylaminoethyl methacrylate and water to the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0027] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethylaminoethyl methacrylate and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluorination agent. Example

[0028] This embodiment provides an adsorption-type defluorination agent based on nanomaterials, including the following raw materials: 11kg nano-alumina, 20kg sulfuric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride and 65kg water.

[0029] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride and water according to the formula ratio.

[0030] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0031] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent. Example

[0032] This embodiment provides an adsorption-type defluorination agent based on nanomaterials, including the following raw materials: 11kg nano-alumina, 20kg nitric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride and 65kg water.

[0033] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride and water according to the formula ratio.

[0034] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0035] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent. Example

[0036] This embodiment provides an adsorption-type defluorination agent based on nanomaterials, including the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride, 0.8kg polyethylene glycol and 65kg water.

[0037] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride, polyethylene glycol and water according to the formula ratio.

[0038] Step 2: Add nano-alumina, dimethyldiallylammonium chloride, polyethylene glycol and water to the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0039] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent.

[0040] Comparative Example 1 This comparative example provides an adsorption-type defluoridation agent based on nanomaterials, comprising the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10% and 65kg water.

[0041] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid and water according to the formula ratio.

[0042] Step 2: Add nano-alumina and water to the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into the ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes, while adding hydrochloric acid dropwise to adjust the pH value of the system to 4.

[0043] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, stir at constant temperature for 80 minutes, and finally cool to room temperature to obtain a defluorination agent.

[0044] Comparative Example 2 This comparative example provides an adsorption-type defluoridation agent based on nanomaterials, comprising the following raw materials: 11kg nano alumina, 3kg dimethyldiallylammonium chloride and 65kg water.

[0045] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, dimethyldiallylammonium chloride and water according to the formula ratio.

[0046] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture preliminarily dispersed in step 2 into an ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65° C. for 30 minutes.

[0047] Step 4: Turn off the ultrasonic generator, raise the temperature to 75°C, and stir at this temperature for 80 minutes to allow the dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent.

[0048] Comparative Example 3 This comparative example provides an adsorption-type defluoridation agent based on nanomaterials, comprising the following raw materials: 11kg nano alumina and 65kg water.

[0049] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano alumina and water according to the formula ratio.

[0050] Step 2: Add nano-alumina and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes to obtain a defluorination agent.

[0051] Comparative Example 4 This comparative example provides an adsorption-type defluoridation agent based on nanomaterials, comprising the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride and 65kg water.

[0052] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride and water according to the formula ratio.

[0053] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add hydrochloric acid to the mixture after preliminary dispersion in step 2 to adjust the pH value of the system to 4.

[0054] Step 4: Raise the temperature to 75°C and stir at constant temperature for 80 minutes to allow dimethyldiallylammonium chloride and nano-alumina to fully chemically bond, and finally cool to room temperature to obtain a defluoridating agent.

[0055] Comparative Example 5 This comparative example provides an adsorption-type defluoridation agent based on nanomaterials, comprising the following raw materials: 11kg nano-alumina, 20kg hydrochloric acid with a mass concentration of 10%, 3kg dimethyldiallylammonium chloride and 65kg water.

[0056] The preparation method of the above-mentioned adsorption-type defluoridating agent based on nanomaterials comprises the following steps: Step 1: Weigh nano-alumina, hydrochloric acid, dimethyldiallyl ammonium chloride and water according to the formula ratio.

[0057] Step 2: Add nano-alumina, dimethyldiallylammonium chloride and water into the reactor, start mechanical stirring (speed of 250 rpm), and mix for 10 minutes until preliminary dispersion; Step 3: Add the mixture after preliminary dispersion in step 2 into an ultrasonic generator, turn on the ultrasonic generator, and perform ultrasonic treatment at 65°C for 30 minutes. At the same time, hydrochloric acid is added dropwise to adjust the pH value of the system to 4. Finally, turn off the ultrasonic generator and cool to room temperature to obtain a defluoridating agent.

[0058] Experimental example The defluorination effects of the defluoridation agents prepared in Examples 1-6 and Comparative Examples 1-5 were tested. Taking the defluoridation effect of wastewater from a centralized industrial wastewater treatment plant in Guangzhou (mainly semiconductor wastewater) as an example, the addition amount of the defluoridation agent was 1496 ppm. The defluoridation effects are shown in Table 1: Table 1 Fluoride removal effect of sewage in a centralized industrial sewage treatment plant in Guangzhou Fluoride content in raw water (mg / L) Fluoride content after treatment (mg / L) Fluoride removal 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 Conclusion: By comparing the data of Example 1 and Example 6, it can be seen that the fluorine removal effect of the fluorine removal agent can be improved by adding a dispersant to the fluorine removal agent formula. By comparing the data of Example 1 and Comparative Examples 1-3, it can be seen that the electrostatic adsorption and chemical bonding (hydroxyl condensation) of the cationic surfactant can form a positively charged adsorption layer (-N + (CH3)3 group), strengthen the electrostatic capture and coordination adsorption of fluoride ions, and in addition, promote the protonation of the nano-alumina surface by adding inorganic acid (Al-OH2 +), further enhancing the chemical adsorption capacity for fluoride ions (forming Al-F coordination bonds). Comparing the data in Example 1 and Comparative Examples 4-5, it can be seen that by increasing the temperature in stages (pre-reacting at 60-70°C for 20-40 minutes, then heating to 75-85°C and stirring for 60-90 minutes), the surfactant is ensured to first rapidly adhere to the surface of the nanoalumina through physical adsorption. High temperature then promotes chemical bonding (such as ester or amide bond formation) to form a stable modified layer. Ultrasonic waves are introduced at the initial stage of the reaction to utilize the cavitation effect to break up nanoparticle agglomerates, promote uniform surfactant coating, and form a stable dispersion system with a narrow particle size distribution. This further increases the grafting rate of the cationic surfactant and enhances the adsorption capacity of the defluoridating agent.

[0059] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative 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. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention fall within the scope of protection of the present invention.

Claims

1. An adsorption-type defluoridant based on nanomaterials, characterized in that: The invention comprises the following raw materials in parts 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.

2. The nanomaterial-based adsorption defluoridant according to claim 1, characterized in that: The cationic surfactant is selected from one of dimethyldiallylammonium chloride and dimethylaminoethyl methacrylate or a mixture of the two; and / or, The particle size of the nano-alumina is 20-80 nm.

3. The nanomaterial-based adsorption defluoridant according to claim 1, characterized in that: 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. The nanomaterial-based adsorption defluoridant according to claim 1, characterized in that: The adsorption-type defluoridating agent further comprises 0.5-1 parts of a dispersant.

5. The nanomaterial-based adsorption-type defluoridating agent according to claim 4, characterized in that: The dispersant is selected from one or more of sodium polyacrylate, polyvinyl alcohol or polyethylene glycol.

6. A method for preparing the nanomaterial-based adsorption defluoridant according to any one of claims 1 to 5, characterized in that: The following steps are involved: The nano-alumina, cationic surfactant, dispersant and water are stirred and mixed, then ultrasonically treated, and inorganic acid is added dropwise to adjust the pH value. Finally, the mixture is heated and stirred to obtain an adsorption-type defluoridating agent.

7. The method for preparing the nanomaterial-based adsorption defluoridant according to claim 6, characterized in that: The temperature of the ultrasonic treatment is 60-70°C; and / or, The ultrasonic treatment time is 20-40 minutes.

8. The method for preparing the nanomaterial-based adsorption defluoridant according to claim 6, characterized in that: The pH value is 3-5.

9. The method for preparing the nanomaterial-based adsorption defluoridant according to claim 6, characterized in that: The temperature of the heating and stirring is 75-85°C; and / or, The time of heating and stirring is 60-90 minutes.

10. The method for preparing the nanomaterial-based adsorption-type defluoridating agent according to claim 6, characterized in that: The stirring and mixing time is 8-12 minutes; and / or, The stirring and mixing speed is 200-300 rpm.