A fluoride removal resin, its preparation method and application

Abstract

This invention relates to the field of materials technology, and discloses a defluorination resin, its preparation method, and its application. The method includes: S1, immersing the resin in a metal salt solution and collecting the metal-loaded resin; S2, mixing the metal-loaded resin with an alkaline solution and reacting, then drying to obtain a first intermediate product; S3, immersing the first intermediate product in a mixed solution containing phenolic substances, aldehyde solution, and water, separating the solid and liquid phases, placing the solid in machine oil, and heating to carry out a Mannich reaction to obtain a second intermediate product; S4, mixing the second intermediate product with an acid solution and activating it to obtain the defluorination resin; the mass ratio of the first intermediate product, phenolic substances, and aldehyde solution is 95-105:15-35:5-30. The method of this invention not only improves the defluorination resin's ability to remove fluoride but also mitigates the performance degradation phenomenon after repeated use.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a fluoride-removing resin, its preparation method, and its application. Background Technology

[0002] Fluorine is an essential trace element for the human body, maintaining healthy bone and teeth development. However, long-term consumption of high-fluoride water can have serious adverse health effects. High-fluoride water is widely distributed in my country, covering 27 provinces, municipalities, and autonomous regions, particularly in the arid and semi-arid regions of North and Northwest China, where groundwater fluoride levels are almost always greater than 1 mg / L. Fluorine-containing industrial wastewater is also a type of inorganic industrial wastewater with a wide industry scope. Large quantities of fluoride-containing wastewater discharged from industries such as steel, aluminum, glass, and pharmaceuticals cause serious pollution and harm to the ecological environment. To effectively address fluoride pollution, countries worldwide have researched and developed various fluoride pollution treatment methods. Currently, the main defluorination methods include precipitation, adsorption, electrochemical methods, ion exchange, and membrane filtration. These conventional treatment processes each have their advantages and disadvantages. Some processes are still relatively ineffective in treating the target pollutant, while others, although achieving good treatment results, are difficult to promote due to economic and technological limitations.

[0003] Chinese patent CN111632579A describes a composite defluorinating agent formed by in-situ deposition of metallic zirconium onto anion exchange resin using a deposition method. Chinese patents CN102942239B and CN106944005A describe defluorinating resins prepared by adsorbing zirconium oxychloride into macroporous resin channels, followed by alkali treatment to form zirconium hydroxide with fluoride adsorption properties within the resin channels. These methods use an impregnation method to attach zirconium to the resin, which is mainly distributed on the resin surface and has difficulty penetrating the internal pores. During the treatment of fluoride-containing wastewater, the adsorption, desorption, and regeneration of the defluorinating resin all result in the loss of a significant amount of effective metal, leading to a decline in the resin's defluorination performance. Therefore, further development of defluorinating resins is needed to address these issues. Summary of the Invention

[0004] This invention addresses the problems of poor fluoride removal capacity and performance degradation after repeated use of existing fluoride removal resins by proposing a fluoride removal resin, its preparation method, and its application.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing a fluoride-removing resin, comprising,

[0006] S1. Immerse the resin in a metal salt solution and collect the resin with the attached metal.

[0007] S2. The metal-loaded resin is mixed with an alkaline solution and reacted, then dried to obtain the first intermediate product.

[0008] S3. The first intermediate product is immersed in a mixed solution containing phenolic substances, aldehyde solution and water, the solid and liquid are separated, the solid is placed in machine oil and heated to carry out the Mannich reaction to obtain the second intermediate product.

[0009] S4. Mix the second intermediate product with an acid solution and activate it to obtain the fluoride removal resin.

[0010] The mass ratio of the first intermediate product, phenolic substances, and aldehyde solution is 95-105:15-35:5-30.

[0011] In step S1, the preparation method also satisfies one or more of the following AF:

[0012] A. The resin is synthesized by polymerizing one or more of styrene, divinylbenzene, and methyl acrylate as monomers and then reacting them with polyamines, or by chelating metal ions with aminocarboxylic acids or aminophosphoric acids as matrices; preferably, the polyamine is selected from at least one of 1,2-propanediamine, diethylenetriamine, triethylenetetramine, and 1,3-propanediamine; more preferably, the resin is selected from at least one of macroporous weakly basic styrene-based anion exchange resin, aminocarboxylic acid chelating resin, and aminophosphoric acid chelating resin.

[0013] B. The metal salt solution has a mass percentage of 15-65 wt%; preferably, the metal salt is selected from at least one of zirconium oxychloride and aluminum trichloride.

[0014] C. The solvent in the metal salt solution is water;

[0015] D. The mass ratio of the resin to the metal salt solution is 1:1-8;

[0016] E. The immersion temperature is 20-100℃, and the time is 2-24h;

[0017] F. Collect the metal-loaded resin by discarding the liquid or removing the liquid by distillation; preferably, collect the metal-loaded resin by removing the liquid by vacuum distillation.

[0018] The resin used in this invention can be prepared using conventional methods in the art, or it can be obtained commercially.

[0019] The present invention involves vacuum distillation for 0.5-3 hours at a temperature of 55-65℃ and a vacuum degree of 0.09-0.1 MPa.

[0020] In step S2, the preparation method further satisfies one or more of the following AC:

[0021] A. The alkaline solution is selected from at least one of sodium hydroxide solution and potassium hydroxide solution; preferably, the concentration of the alkaline solution is 2g / 100mL-15g / 100mL; more preferably, the concentration of the alkaline solution is 8g / 100mL-15g / 100mL.

[0022] B. The mass ratio of the resin carrying the metal to the alkaline solution is 1:1-7;

[0023] C. The reaction temperature is 20-80℃, and the reaction time is 2-8h.

[0024] The mass ratio of the first intermediate product, phenolic substances, and aldehyde solution is 95-105:15-25:5-20.

[0025] The phenolic substance is selected from at least one of phenol, cresol, and hydroquinone; and / or, the aldehyde solution is selected from at least one of formaldehyde solution, acetaldehyde solution, and pentanal solution; and / or, the concentration of the aldehyde solution is 36.5-38 wt%; and / or, the mass ratio of the phenolic substance, aldehyde solution, and water is 1:0.5-5:5-20; and / or, the engine oil is turbine oil; and / or, the mass ratio of the first intermediate product to the engine oil is 1:2-8; and / or, the temperature of the Mannich reaction is 70-120°C, and the time is 2-10 h.

[0026] In step S3, the immersion temperature is 20-60℃ and the time is 2-15h; preferably, the immersion temperature is 20-30℃.

[0027] The normal temperature refers to 23-27℃.

[0028] The acid solution is selected from at least one of hydrochloric acid aqueous solution and sulfuric acid aqueous solution; and / or, the concentration of the acid solution is 1-15%; and / or, the volume of the acid solution is 2-5 times the volume of the second intermediate product; and / or, the activation time is 3-8 hours.

[0029] The resin is further subjected to washing with water until the pH of the water is 6.8-7.2 and drying of the resin before use.

[0030] The present invention also provides a method for preparing the above-mentioned defluorination resin to obtain the defluorination resin.

[0031] The defluorinating resin of the present invention can be regenerated using conventional methods in the art after use. The regenerated defluorinating resin can be reused without performance degradation. For example, the regeneration process may include the following steps: water washing, alkaline solution elution, water washing, acidic solution activation, and water washing.

[0032] The present invention also provides a fluoride removal resin column, comprising the above-mentioned fluoride removal resin.

[0033] The present invention also provides a method for preparing a defluorinating resin and the application of the defluorinating resin or defluorinating resin column in the treatment of fluoride pollution.

[0034] The application of the defluorination resin includes preparing it into a defluorination resin column using conventional methods in the art for the treatment of fluoride pollution.

[0035] The technical solution of the present invention has the following beneficial effects:

[0036] (1) The present invention provides a method for preparing a defluorinating resin, comprising: S1, immersing the resin in a metal salt solution and collecting the resin loaded with metal; S2, mixing the resin loaded with metal with an alkaline solution and reacting it, drying it to obtain a first intermediate product; S3, immersing the first intermediate product in a mixed solution containing phenolic substances, aldehyde solution and water, separating the solid and liquid, placing the solid in machine oil, heating it to carry out the Mannich reaction, and obtaining a second intermediate product; S4, mixing the second intermediate product with an acid solution and activating it to obtain a defluorinating resin; the mass ratio of the first intermediate product, phenolic substances and aldehyde solution is 95-105:15-35:5-30. This invention prepares a resin selective for fluoride ions, namely the first intermediate product, by impregnating resin in a metal salt solution and then reacting it with an alkaline solution. The first intermediate product is then impregnated in a mixed solution containing phenolic substances, aldehyde solution, and water at a specific ratio. A Mannich reaction is then carried out by heating in engine oil and activation in an acid solution, which strengthens the binding ability between the metal and the resin. This not only improves the fluoride removal resin's ability to remove fluoride but also mitigates the performance degradation that occurs after repeated use. Furthermore, it enhances the selectivity of the fluoride removal resin for fluoride. In this invention, aldehydes (formaldehyde) and phenols (phenol) adsorbed on the surface of the first intermediate product undergo a Mannich reaction with primary or secondary amines on the resin at high temperature, resulting in a tighter cross-linking, meaning the metal is tightly cross-linked onto the resin. Furthermore, the hydroxymethyl group generated by the condensation reaction of aldehydes (formaldehyde) and phenols (phenol) condenses with the active hydrogen on the benzene ring of the resin to form a polyphenolic alcohol bridged by methylene groups. The phenolic hydroxyl groups on the polyphenolic alcohol further form bihydroxyl bridges with two adjacent metals on the resin surface, firmly binding the metals and reducing the loss of metals from the defluorination resin, thereby improving the performance degradation phenomenon of the defluorination resin after repeated use. This invention involves immersing the first intermediate product in a mixed solution containing phenols, aldehyde solution, and water, allowing the aldehydes (formaldehyde) and phenols (phenol) in the aldehyde solution to adsorb onto the resin surface. Then, the resin is placed in engine oil (turbine oil) for reaction. Since phenols and aldehydes are insoluble in engine oil, the utilization rate of raw materials can be improved. Simultaneously, heating the reaction accelerates the reaction rate, shortens the reaction time, and reduces production costs. Compared to hydrothermal reactions, phenols and aldehydes have a higher solubility in water, resulting in a large amount of raw materials dissolving in water and causing waste. Furthermore, phenols and aldehydes dissolved in water can undergo emulsification, affecting their polymerization and leading to a decline in product performance.

[0037] (2) The present invention provides a method for preparing a defluorination resin. In step S1, the resin loaded with metal is collected by discarding the liquid or removing the liquid by distillation; preferably, the resin loaded with metal is collected by removing the liquid by vacuum distillation. The method of collecting the resin loaded with metal by distillation can greatly increase the amount of metal loaded on the resin, thereby improving the resin's ability to treat fluoride. Secondly, this method can ensure that all metals are loaded on the resin, reducing the amount of metal salt solution used and greatly reducing the production cost of the defluorination resin.

[0038] (3) The present invention provides a method for preparing a fluoride removal resin. By further limiting the concentration of the alkaline solution in step S2 to 8g / 100mL-15g / 100mL, the present invention further improves the resin’s ability to remove fluoride.

[0039] (4) The present invention provides a method for preparing a fluoride removal resin. The present invention further improves the resin’s ability to remove fluoride by further limiting the mass ratio of the first intermediate product, phenolic substance and aldehyde solution in step S3 to 95-105:15-25:5-20.

[0040] (5) The present invention provides a method for preparing a fluoride removal resin. By further limiting the impregnation temperature in step S3 to 20-30°C, the present invention further improves the resin’s ability to remove fluoride. Detailed Implementation

[0041] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0042] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagents. Macroporous weakly basic styrene-based anion exchange resin (Xunyang Lingsheng New Material Technology Co., Ltd., D201*7); aminocarboxylic acid chelating resin (Xunyang Lingsheng New Material Technology Co., Ltd., ACD-100); aminophosphate chelating resin (Xunyang Lingsheng New Material Technology Co., Ltd., ACD-500); turbine oil (Great Wall Weiyue No. 32 long-life turbine oil).

[0043] Example 1

[0044] This embodiment provides a method for preparing a fluoride-removing resin, the specific method being as follows:

[0045] S1. Weigh 100g of macroporous weakly basic styrene-based anion exchange resin, rinse the resin with deionized water until the pH of the deionized water reaches 7.0, discard the deionized water, and dry the resin. Using water as a solvent, prepare 100g of a 50% (w / w) zirconium oxychloride solution. Add the dried resin to the zirconium oxychloride solution for impregnation, then heat the solution to 80℃ and impregnate at 80℃ for 8 hours. After impregnation, add the resin and solution together to a rotary evaporator and perform vacuum distillation for 30 minutes at 60℃ and a vacuum degree of 0.1 MPa to remove the liquid. Collect the resin loaded with metallic zirconium.

[0046] S2. Add 100g of the zirconium-loaded resin obtained in step S1 to 400g of sodium hydroxide solution with a concentration of 10g / 100mL. Stir and react at room temperature for 5h, then filter and dry to obtain the first intermediate product.

[0047] S3. Take 18g of phenol and 16.5g of formaldehyde solution (concentration 36.5wt%) and add them to 200g of water to prepare a mixed solution. Then add 100g of the first intermediate product obtained in step S2 to the mixed solution, soak at room temperature for 3 hours, and then filter. Add the filtered resin to 500g of turbine oil and stir at 90℃ for 5 hours. After the reaction is complete, filter, pack the filtered resin into a column, and wash with methylal until the eluent does not separate into layers when water is added. Then dry the resin to obtain the second intermediate product.

[0048] S4. Take 100 mL of the second intermediate product and add it to 400 mL of a 5% hydrochloric acid aqueous solution. Activate at room temperature for 5 h to obtain the fluoride removal resin.

[0049] Example 2

[0050] This embodiment provides a method for preparing a fluoride-removing resin. The preparation method is basically the same as that in Example 1, except that in step S3, "take 18g of phenol and 16.5g of formaldehyde solution (concentration of 36.5wt%) and add it to 200g of water" is replaced with "take 27g of phenol and 25g of formaldehyde solution (concentration of 36.5wt%) and add it to 200g of water".

[0051] Example 3

[0052] This embodiment provides a method for preparing a fluoride-removing resin. The preparation method is basically the same as that in Example 2, except that in step S3, "immersing at room temperature for 3 hours and then filtering" is replaced with "immersing at 60°C for 3 hours and then filtering".

[0053] Example 4

[0054] This embodiment provides a method for preparing a fluoride removal resin, which is basically the same as that in Example 1, except that the "macroporous weakly basic styrene-based anion exchange resin" is replaced with "aminocarboxylic acid chelating resin ACD-100".

[0055] Example 5

[0056] This embodiment provides a method for preparing a fluoride removal resin, which is basically the same as that in Example 1, except that the "macroporous weakly basic styrene-based anion exchange resin" is replaced with "aminophosphate chelating resin ACD-500".

[0057] Example 6

[0058] This embodiment provides a method for preparing a fluoride-removing resin, which is basically the same as that in Example 1, except that steps S1 and S2 are different. In this embodiment, step S1 is as follows: "Weigh 100g of macroporous weakly basic styrene-based anion exchange resin, rinse the resin with deionized water until the pH of the deionized water is 7.0, discard the deionized water, and dry the resin; use water as a solvent to prepare 100g of 30% (w / w) aluminum trichloride solution, add the dried resin to the aluminum trichloride solution for impregnation, and then heat the solution to 60°C and impregnate at 60°C for 5 hours. After impregnation, filter the resin and solution, discard the liquid, and collect the resin loaded with metallic aluminum"; Step S2 is as follows: "Add 100g of the resin loaded with metallic aluminum obtained in step S1 to 100g of sodium hydroxide solution with a concentration of 10g / 100mL, stir and react at 40°C for 5 hours, and then filter to obtain the first intermediate product."

[0059] Example 7

[0060] This embodiment provides a method for preparing a fluoride-removing resin. The preparation method is basically the same as that in Embodiment 2, except that in step S1, "adding the resin and solution together into a rotary evaporator and performing vacuum distillation for 30 minutes at a temperature of 60°C and a vacuum degree of 0.1 MPa to remove the liquid" is replaced with "filtering the resin and solution and discarding the liquid".

[0061] Example 8

[0062] This embodiment provides a method for preparing a fluoride removal resin. The preparation method is basically the same as that in Example 1, except that in step S2, "10g / 100mL sodium hydroxide solution" is replaced with "5g / 100mL sodium hydroxide solution".

[0063] Comparative Example 1

[0064] This comparative example provides a fluoride removal resin, the preparation method of which includes:

[0065] S1. Weigh 100g of macroporous weakly basic styrene-based anion exchange resin, rinse the resin with deionized water until the pH of the deionized water reaches 7.0, discard the deionized water, and dry the resin. Using water as a solvent, prepare 200g of a 50% (w / w) zirconium oxychloride solution. Add the dried resin to the zirconium oxychloride solution for impregnation, then heat the solution to 80℃ and impregnate at 80℃ for 8 hours. After impregnation, filter the resin and solution, discard the liquid, then rinse the resin with deionized water, discard the deionized water again, and collect the resin loaded with metallic zirconium.

[0066] S2. Add 100g of the zirconium-loaded resin obtained in step S1 to 100g of sodium hydroxide solution with a concentration of 5g / 100mL, stir and react at 40℃ for 5h, and then filter to obtain the fluoride-removing resin.

[0067] Comparative Example 2

[0068] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 1, except that steps S3 and S4 are not performed.

[0069] Comparative Example 3

[0070] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 3. The only difference is that in step S2, "take 18g of phenol and 16.5g of formaldehyde solution (concentration of 36.5wt%) and add it to 200g of water" is replaced with "take 54g of phenol and 50g of formaldehyde solution (concentration of 36.5wt%) and add it to 200g of water".

[0071] Comparative Example 4

[0072] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 1, except that in step S3, "turbo oil" is replaced with "water".

[0073] Comparative Example 5

[0074] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 1, except that step S4 is not performed.

[0075] Comparative Example 6

[0076] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 1. The only difference is that in step S3, "take 100g of the first intermediate product obtained in step S2" is replaced with "take 100g of the resin loaded with zirconium metal obtained in step S1", and step S2 is not performed.

[0077] Comparative Example 7

[0078] This comparative example provides a fluoride removal resin, and the preparation method is basically the same as that in Example 1, except that step S3 is not performed.

[0079] Experimental Example 1

[0080] The zirconium content and fluorine adsorption capacity of the defluorinating resins prepared in each embodiment and comparative example were tested.

[0081] Method for detecting zirconium content: Weigh 3g of the fluoride-removing resin prepared in each example and comparative example and place it in a silver crucible. Add 2.5g of sodium hydroxide and 2.5g of potassium nitrate reagent. Cover the crucible and heat it on an electric furnace for 10 minutes until it smokes, then continue heating for another 5 minutes. Remove the silver crucible and, while it is still solidifying, wash the substance in the silver crucible into a handled porcelain crucible with hot pure water, carefully rinsing the silver crucible. After the solution temperature drops, add 1 drop of phenolphthalein indicator solution and neutralize with 40% hydrofluoric acid aqueous solution until the phenolphthalein just turns colorless. Then place the solution in a graduated cylinder and dilute it with water to 500mL. Take 10mL of the sample and send it to an ICP (internal emission spectrometer) to detect the zirconium content.

[0082] Method for detecting fluoride adsorption: A dynamic adsorption method was used. A 100 mg / L sodium fluoride aqueous solution (Cl = 100 mg / L) was passed at a flow rate of 5 BV / h through a resin column (30 cm long, 2.5 cm in diameter, resin packing volume: 50 mL) packed with the defluorination resin prepared in each example and comparative example. The solution after treatment by the defluorination resin column was collected in a beaker. Samples were taken from the beaker every 5 BV to detect the fluoride concentration in the sampled solution. Sampling was stopped when the fluoride concentration in the sampled solution exceeded 1 mg / L. The total volume multiple of the sodium fluoride aqueous solution treated by the defluorination resin column at the time of the last sample was recorded, and the fluoride concentration in the beaker was recorded as 1 mg / L (Cl). The fluoride adsorption capacity of the defluorination resin was calculated using the following formula:

[0083]

[0084] Wherein: C2- represents the initial concentration of fluorine in the sodium fluoride aqueous solution;

[0085] C1- represents the fluoride concentration in the solution after sodium fluoride aqueous solution has been treated with a fluoride removal resin column;

[0086] A- represents the packing volume of the resin in the fluoride removal resin column;

[0087] B represents the volume multiple of the resin packing column (when B is 1BV, it means that the total volume of the treated sodium fluoride aqueous solution is 1×AmL).

[0088] The measurement results of Examples 1-3, Examples 7-8, and Comparative Examples 1-3 and 5-6 are shown in Table 1 below. Compared with Comparative Example 1, the zirconium content of the defluorinating resins prepared in Examples 1-3 and 7-8 is superior. Compared with Comparative Examples 1-3 and 5-6, the fluoride adsorption capacity of the defluorinating resins prepared in Examples 1-3 and 7-8 is significantly improved, indicating that the defluorinating resin column prepared by the method of the present invention has a greatly improved fluoride removal capacity. Among them, the addition of too much phenol and formaldehyde solution in Comparative Example 3 resulted in a lower removal capacity for sodium fluoride aqueous solution. This is mainly because the excessive phenol reacts with the formaldehyde in the formaldehyde solution to form phenolic resin. The phenolic resin encapsulates the macroporous anion exchange resin carrying metallic zirconium, making it difficult for the sodium fluoride aqueous solution to enter the internal pores of the zirconium-carrying resin. Therefore, the fluoride removal capacity is significantly reduced, resulting in a lower fluoride adsorption capacity. Comparative Examples 5 and 6, due to the absence of acid and alkali activation treatments respectively, exhibited significantly reduced fluoride removal capabilities, resulting in lower fluoride adsorption amounts. Compared to Example 2, Example 1 further improved the fluoride removal resin column's processing capacity by limiting the mass ratio of the first intermediate product, phenolic substances, and aldehyde solution within a preferred range. Compared to Example 3, Example 2 further improved the fluoride removal resin column's processing capacity by limiting the impregnation temperature in step S3 within a preferred range. Compared to Example 7, Example 1 further improved the fluoride removal resin column's processing capacity by collecting the metal-loaded resin through distillation in step S1. Compared to Example 8, Example 1 further improved the fluoride removal resin column's processing capacity by limiting the sodium hydroxide concentration within a preferred range in step S2.

[0089] Table 1 Measurement Results

[0090]

[0091]

[0092] Experimental Example 2

[0093] The defluorination capacity of the defluorination resins prepared in each embodiment and comparative example was tested over multiple cycles. Specifically, a sodium fluoride aqueous solution with a fluoride concentration of 100 mg / L was prepared; the defluorination resin was packed into a column (30 cm long, 2.5 cm in diameter, resin packing volume: 50 ml); the sodium fluoride aqueous solution was then passed through the defluorination resin column prepared in each embodiment and comparative example at a flow rate of 5 BV / h; the solution treated with the defluorination resin column was sampled (once per hour) and the fluoride content was measured. When the measured fluoride content was greater than 1 ppm, 2 BV of deionized water was added to the defluorination resin column for rinsing, and after draining, 2.5 BV of 5% (w / w) sodium hydroxide solution was added at a flow rate of 2 BV / h for elution. After elution, the column was washed with 2 BV of deionized water, and then with 3 BV of deionized water. Activation was performed using a 3% (w / w) sulfuric acid solution, followed by rinsing with deionized water until the outlet pH reached 6-8. After resin regeneration, the next defluorination cycle was initiated. The above steps were repeated for a total of five cycles. The amount of sodium fluoride aqueous solution processed in each cycle (bed volume, unit BV) was recorded. The defluorination performance degradation rate for the second to fifth cycles was calculated using the formula: degradation rate % = (1-A / B)*100%, where A is the bed volume processed in the second to fifth cycles and B is the bed volume processed in the first cycle.

[0094] The treatment results of sodium fluoride aqueous solution by the defluorinating resins prepared in Examples 1-3, Example 8, and Comparative Examples 1-7 are shown in Table 2 below. As can be seen from Table 2, the defluorinating resin columns prepared in Examples 1-3 and Example 8 showed good treatment capacity when treating sodium fluoride aqueous solution in the second to fifth cycles. In Comparative Example 3, the addition of excessive phenol and formaldehyde solution resulted in lower treatment capacity of sodium fluoride aqueous solution in the first to fifth cycles. This was mainly because the excessive phenol reacted with formaldehyde in the formaldehyde solution to form phenolic resin, which encapsulated the macroporous anion exchange resin carrying zirconium metal, making it difficult for sodium fluoride aqueous solution to enter the internal channels of the zirconium-loaded resin, thus reducing the defluorination capacity.

[0095] Table 2 Measurement Results

[0096]

[0097]

[0098] The results of the defluorination performance degradation rates of the defluorination resins prepared in Examples 1-3, Example 8, and Comparative Examples 1-7 after multiple cycles of treatment with sodium fluoride aqueous solution are shown in Table 3 below. As shown in Table 3, compared with Comparative Examples 1-4 and 7, the defluorination performance degradation rates of the defluorination resin columns prepared in Examples 1-3 and 8 were 0% from the second to the fifth cycle, indicating that the defluorination resin prepared by the method of this invention can significantly improve the performance degradation phenomenon after multiple uses. Referring to Table 2, although the degradation rates of the defluorination resin columns prepared in Comparative Examples 3 and 5-6 were 0%, their low fluoride removal capacity is not practically significant.

[0099] Table 3 Measurement Results

[0100]

[0101] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a fluoride-removing resin, characterized in that, include, S1. Immerse the resin in a metal salt solution and collect the metal-loaded resin; S2. The metal-loaded resin is mixed with an alkaline solution and reacted, then dried to obtain the first intermediate product. S3. The first intermediate product is immersed in a mixed solution containing phenolic substances, aldehyde solution and water, the solid and liquid are separated, the solid is placed in machine oil and heated to carry out the Mannich reaction to obtain the second intermediate product. S4. Mix the second intermediate product with an acid solution and activate it to obtain the fluoride removal resin. The mass ratio of the first intermediate product, phenolic substances, and aldehyde solution is 95-105:15-35:5-30; The resin is synthesized by polymerizing one or more of styrene, divinylbenzene, and methyl acrylate as monomers and then reacting them with polyamines, or by chelating metal ions with aminocarboxylic acid or aminophosphoric acid as a matrix; or the resin is selected from at least one of macroporous weakly basic styrene-based anion exchange resin, aminocarboxylic acid chelating resin, and aminophosphoric acid chelating resin; the engine oil is turbine oil. The metal salt is selected from at least one of zirconium oxychloride and aluminum trichloride.

2. The method for preparing the defluorinating resin according to claim 1, characterized in that, In step S1, the preparation method further satisfies one or more of the following AF: A. The polyamine is selected from at least one of 1,2-propanediamine, diethylenetriamine, triethylenetetramine, and 1,3-propanediamine; B. The mass percentage of the metal salt solution is 15-65 wt%. C. The solvent in the metal salt solution is water; D. The mass ratio of the resin to the metal salt solution is 1:1-8; E. The immersion temperature is 20-100℃, and the time is 2-24h; F. Collect the metal-loaded resin by discarding the liquid or removing the liquid by distillation.

3. The method for preparing the defluorinating resin according to claim 1, characterized in that, Metal-loaded resins are collected by removing the liquid through vacuum distillation.

4. The method for preparing the defluorinating resin according to claim 1, characterized in that, In step S2, the preparation method further satisfies one or more of the following AC: A. The alkaline solution is selected from at least one of sodium hydroxide solution and potassium hydroxide solution; B. The mass ratio of the metal-loaded resin to the alkaline solution is 1:1-7; C. The reaction temperature is 20-80℃, and the reaction time is 2-8h.

5. The method for preparing the fluoride-removing resin according to claim 4, characterized in that, The concentration of the alkaline solution is 2g / 100mL-15g / 100mL.

6. The method for preparing the defluorinating resin according to claim 4, characterized in that, The concentration of the alkaline solution is 8g / 100mL-15g / 100mL.

7. The method for preparing the fluoride-removing resin according to claim 1, characterized in that, The mass ratio of the first intermediate product, phenolic substances, and aldehyde solution is 95-105:15-25:5-20.

8. The method for preparing the defluorinating resin according to claim 1, characterized in that, The phenolic substance is selected from at least one of phenol, cresol, and hydroquinone; and / or, the aldehyde solution is selected from at least one of formaldehyde solution, acetaldehyde solution, and pentanal solution; and / or, the concentration of the aldehyde solution is 36.5-38 wt%; and / or, the mass ratio of the phenolic substance, aldehyde solution, and water is 1:0.5-5:5-20; and / or, the mass ratio of the first intermediate product to engine oil is 1:2-8; and / or, the temperature of the Mannich reaction is 70-120°C, and the time is 2-10 h.

9. The method for preparing the defluorinating resin according to claim 1, characterized in that, In step S3, the immersion temperature is 20-60℃ and the time is 2-15h.

10. The method for preparing the defluorinating resin according to claim 1, characterized in that, In step S3, the immersion temperature is 20-30℃.

11. The method for preparing the defluorinating resin according to any one of claims 1-10, characterized in that, The acid solution is selected from at least one of hydrochloric acid aqueous solution and sulfuric acid aqueous solution; and / or, the concentration of the acid solution is 1-15%; and / or, the volume of the acid solution is 2-5 times the volume of the second intermediate product; and / or, the activation time is 3-8 hours.

12. A defluorinating resin is prepared by any of the methods described in claims 1-11.

13. A fluoride-removing resin column, characterized in that, Includes the fluoride-removing resin according to claim 12.

14. The application of the defluorinating resin prepared by any of the methods described in claims 1-11, or the defluorinating resin column described in claim 13, in the treatment of fluoride pollution.

Images