Polymer microsphere as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polymer synthesis, in particular to polymer microspheres and a preparation method and application thereof.The preparation method of the polymer microspheres comprises the following steps that pyridoxal, an anhydrous aprotic polar solvent, organic alkali and methacryloyl chloride are mixed to be subjected to an esterification reaction under the conditions of protective gas and light shielding, and the polymer microspheres are obtained. Pyridoxal methacrylate is prepared; dissolving inorganic salt and a dispersing agent in water to prepare a water phase; the preparation method comprises the following steps: mixing pyridoxal methacrylate, styrene, divinyl benzene and an initiator to prepare an oil phase; heating the water phase to 65-75 DEG C, and adding the oil phase into the water phase under a stirring condition to prepare a suspension dispersion system; under the protection of protective gas, the suspension dispersion system is subjected to a reaction for 8-12 h at the temperature of 65-75 DEG C, the polymer microspheres are prepared, and the polymer microspheres can keep efficient adsorption of uranyl ions within a wide pH range.

Description

Technical Field

[0001] This application relates to the field of polymer synthesis technology, and in particular to polymer microspheres, their preparation methods, and applications. Background Technology

[0002] Uranium mainly exists as uranyl ions (UO2). 2+ Uranyl ions exist in water bodies in the form of heavy metal chemical toxicity and radioactive hazards. They also have strong migration ability and are easily ingested by organisms. Once they enter the body of an organism, they will cause serious damage to the organism's organs and tissues, and even death.

[0003] Meanwhile, the existence of uranyl ions is heavily dependent on the pH value of the water body, and changes in their morphology significantly affect their reactivity and mobility. Under strongly acidic conditions, uranyl ions mainly exist as positively charged mononuclear hydrated ions with small hydration radii and strong migration capabilities. When the pH rises to around 5, they begin to hydrolyze and form polynuclear hydroxyl complexes, resulting in a more complex morphology. Under weakly acidic to neutral conditions, they readily undergo complexation reactions with some anions in the solution to form negatively charged complex ions. In other words, even small changes in pH can lead to significant differences in the existence form of uranyl ions, posing a significant challenge to their capture and recovery. Taking the traditionally widely used high-efficiency adsorption group—ammoxime resin—as an example, it only performs well under near-neutral or weakly alkaline conditions. In common moderately to strongly acidic environments such as uranium tailings leachate, its adsorption capacity drops sharply, making it difficult to effectively capture uranyl ions, which are mainly in cationic form.

[0004] Therefore, how to provide a material with wide pH adaptability that can efficiently adsorb uranyl ions is an urgent problem to be solved. Summary of the Invention

[0005] Based on this, this application provides polymer microspheres, their preparation methods, and applications, wherein the polymer microspheres maintain efficient adsorption of uranyl ions over a wide pH range.

[0006] The first aspect of this application provides a method for preparing polymer microspheres, comprising the following steps:

[0007] Under protective gas and light-protected conditions, pyridoxal, anhydrous aprotic polar solvent, organic base and methacryloyl chloride were mixed and subjected to esterification reaction to prepare pyridoxal methacrylate.

[0008] An aqueous phase is prepared by dissolving inorganic salts and dispersants in water;

[0009] The oil phase was prepared by mixing pyridoxal methacrylate, styrene, divinylbenzene, and an initiator.

[0010] After heating the aqueous phase to 65℃~75℃, the oil phase is added to the aqueous phase under stirring conditions to prepare a suspension dispersion system.

[0011] Polymer microspheres were prepared by reacting the suspended dispersion system at 65℃~75℃ for 8h~12h under the protection of a protective gas.

[0012] In some embodiments, the step of preparing pyridoxal methacrylate includes: adding an organic base to an anhydrous aprotic polar solvent containing pyridoxal under protective gas and light-protected conditions, cooling to -10°C to 10°C, adding methacryloyl chloride dropwise, and then carrying out an esterification reaction at room temperature to prepare pyridoxal methacrylate. In some embodiments, the step of preparing pyridoxal methacrylate satisfies at least one of the following conditions: (1) the molar ratio of pyridoxal to methacryloyl chloride is 1:(0.9~1.1); (2) the anhydrous aprotic polar solvent includes one or more of anhydrous tetrahydrofuran, anhydrous dichloromethane, and anhydrous diethyl ether; (3) the organic base includes one or more of triethylamine, tri-n-butylamine, tri-n-pentylamine, tripropylamine, and N,N-diisopropylethylamine.

[0013] In some embodiments, the esterification step is followed by a purification process, which includes sequential filtration, concentration of the filtrate, and column chromatography.

[0014] In some embodiments, the step of preparing the aqueous phase satisfies at least one of the following conditions: (1) the inorganic salt includes one or more of sodium chloride, sodium phosphate, sodium dihydrogen phosphate, sodium monohydrogen phosphate and sodium carbonate; (2) the dispersant includes one or more of polyvinyl alcohol, gelatin, polyvinylpyrrolidone, hydroxyethyl cellulose, gourd, methyl cellulose, sodium dodecylbenzene sulfonate and sodium lignin sulfonate.

[0015] In some embodiments, the step of preparing the oil phase satisfies at least one of the following conditions: (1) the mass percentage of pyridoxal methacrylate is 38% to 49% based on 100% of the mass of the oil phase; (2) the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0016] In some embodiments, after reacting the suspended dispersion system at 65°C to 75°C for 8 to 12 hours under the protection of a protective gas, post-treatment is also included, which includes cooling, filtration, washing and drying in sequence.

[0017] The second aspect of this application provides a polymer microsphere prepared using the same method as that provided in the first aspect of this application.

[0018] The third aspect of this application provides the application of the polymer microspheres prepared by the method of the first aspect of this application in the adsorption of uranyl ions in a solution.

[0019] In some implementations, the pH of the solution is 1 to 7.5.

[0020] Compared with traditional technologies, this application has the following advantages:

[0021] This application provides a pyridoxal-based polymer microsphere by converting pyridoxal into pyridoxal methacrylate monomer and then performing suspension copolymerization. This polymer microsphere utilizes the synergistic coordination effect of the aldehyde group and pyridine nitrogen in the pyridoxal molecule to achieve efficient and selective adsorption of uranyl ions over a wide pH range. On one hand, the pyridine nitrogen in the pyridoxal molecule first coordinates with the uranyl ion through its lone pair electrons, anchoring the uranyl ion near the polymer microsphere. The molecular conformation of the uranyl ion adjusts during the anchoring process, allowing the oxygen atom of the aldehyde group in the pyridoxal molecule to enter a suitable coordination site and bind to the uranyl ion. The chelation effect generated by the synergistic interaction of the pyridine nitrogen and the aldehyde functional group firmly adsorbs the uranyl ion. On the other hand, after the pyridine nitrogen atom provides an electron pair, the conjugated system of its aromatic ring effectively disperses some of the positive charge generated by coordination, and the coordination of the aldehyde oxygen also contributes to the electron density. Together, these two factors stabilize the chemical bond between the uranyl ion and the ligand, making the uranyl ion less susceptible to H+ ion degradation under acidic conditions. + It dissociates upon protonation. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram illustrating the preparation method of polymer microspheres in some embodiments of this application. Detailed Implementation

[0024] A detailed reference is now provided to embodiments of this application, one or more of which are described below. Each embodiment is provided for explanation and not for limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0025] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0026] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0027] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0028] In this article, when referring to units of data ranges, if a unit is only followed by the right endpoint, it means that the units of the left and right endpoints are the same.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0033] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0034] like Figure 1 As shown, the first aspect of this application provides a method for preparing polymer microspheres, comprising the following steps:

[0035] S1. Under protective gas and light-protected conditions, pyridoxal, anhydrous aprotic polar solvent, organic base, and methacryloyl chloride are mixed and subjected to an esterification reaction to prepare pyridoxal methacrylate.

[0036] S2. Dissolve the inorganic salt and dispersant in water to prepare an aqueous phase.

[0037] S3. Mix pyridoxal methacrylate, styrene, divinylbenzene and an initiator to prepare an oil phase.

[0038] S4. After heating the aqueous phase to 65℃~75℃, add the oil phase to the aqueous phase under stirring conditions to prepare a suspension dispersion system.

[0039] S5. Under the protection of protective gas, the suspended dispersion system is reacted at 65℃~75℃ for 8h~12h to prepare polymer microspheres.

[0040] It should be noted that the limitations of steps S1-S3 involved in this application are not considered as limiting the order of steps, provided that they do not affect the implementation of the specific solution. The steps listed first can be performed first, later, or even simultaneously. As long as this application can be implemented, they should be considered to fall within the scope of protection of this application.

[0041] This application provides a pyridoxal-based polymer microsphere by converting pyridoxal into pyridoxal methacrylate monomer and then performing suspension copolymerization. This polymer microsphere utilizes the synergistic coordination effect of the aldehyde group and pyridine nitrogen in the pyridoxal molecule to achieve efficient and selective adsorption of uranyl ions over a wide pH range. On one hand, the pyridine nitrogen in the pyridoxal molecule first coordinates with the uranyl ion through its lone pair electrons, anchoring the uranyl ion near the polymer microsphere. The molecular conformation of the uranyl ion adjusts during the anchoring process, allowing the oxygen atom of the aldehyde group in the pyridoxal molecule to enter a suitable coordination site and bind to the uranyl ion. The chelation effect generated by the synergistic interaction of the pyridine nitrogen and the aldehyde functional group firmly adsorbs the uranyl ion. On the other hand, after the pyridine nitrogen atom provides an electron pair, the conjugated system of its aromatic ring effectively disperses some of the positive charge generated by coordination, and the coordination of the aldehyde oxygen also contributes to the electron density. Together, these two factors stabilize the chemical bond between the uranyl ion and the ligand, making the uranyl ion less susceptible to H+ ion degradation under acidic conditions. + It dissociates upon protonation.

[0042] In one embodiment, in S1 above, the protective gas includes one or more of nitrogen, helium, neon, argon, krypton, and xenon. Further, the protective gas is nitrogen.

[0043] In one embodiment, in S1 above, the molar ratio of pyridoxal to methacryloyl chloride is 1:(0.9~1.1), for example 1:0.9, 1:1, 1:1.1, and any value within the range of any two of the above values.

[0044] In some embodiments, in S1 above, the organic base includes one or more of triethylamine, tri-n-butylamine, tri-n-pentylamine, tripropylamine, and N,N-diisopropylethylamine. Further, the organic base is triethylamine.

[0045] In some embodiments, in S1 above, the anhydrous aprotic polar solvent includes one or more of anhydrous tetrahydrofuran, anhydrous dichloromethane, and anhydrous diethyl ether. Further, the anhydrous aprotic polar solvent is anhydrous tetrahydrofuran.

[0046] In some embodiments, the step of preparing pyridoxal methacrylate in S1 above includes: adding an organic base to an anhydrous aprotic polar solvent containing pyridoxal under protective gas and light-protected conditions, cooling to -10°C to 10°C, adding methacryloyl chloride dropwise, and then carrying out an esterification reaction at room temperature to prepare pyridoxal methacrylate. The reaction formula for the esterification reaction is shown below:

[0047] .

[0048] In some embodiments, the term "room temperature" in this application generally refers to 15°C to 30°C, including but not limited to 15°C, 17°C, 20°C, 22°C, 25°C, 27°C, and 30°C. It should be noted that in the specific embodiments and comparative examples of this application, when room temperature is mentioned without any special explanation, "room temperature" refers to 25°C.

[0049] In some embodiments, the esterification reaction is carried out at room temperature for 10 to 14 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or any value within the range of any two of the above values. Further, the esterification reaction is carried out at room temperature for 12 hours.

[0050] In some embodiments, cooling to -10°C to 10°C is employed using an ice-water bath, for example, -10°C, -5°C, 0°C, 5°C, 10°C, or any value within the range of any two of the above values. Further, cooling to 0°C is employed. Cooling to such a low temperature using an ice-water bath suppresses side reactions between the aldehyde group and trace amounts of water or alkali in the system; simultaneously, it ensures that the addition of methacryloyl chloride is gentle and controllable, avoiding premature polymerization of methacryloyl chloride or the resulting ester due to sudden and violent exothermic reactions; and it guarantees that the reaction mainly occurs on the target aldehyde group.

[0051] In some embodiments, the esterification reaction step in S1 above is followed by a purification process, which includes sequential filtration, concentration of the filtrate, and column chromatography separation.

[0052] In one specific embodiment, after the esterification reaction is completed, the solid salt is removed by filtration, the filtrate is concentrated by rotary evaporation, and the crude product is purified by silica gel column chromatography (eluent: V(ethyl acetate) / V(petroleum ether) = 1 / 1) to obtain the white solid product pyridoxal methacrylate.

[0053] In some embodiments, the water in S2 above is purified water, such as distilled water, deionized water, etc.

[0054] In some embodiments, in S2 above, the inorganic salt includes one or more of sodium chloride, sodium phosphate, sodium dihydrogen phosphate, sodium monohydrogen phosphate, and sodium carbonate. Further, the inorganic salt is sodium chloride.

[0055] In some embodiments, in S2 above, the dispersant includes one or more of polyvinyl alcohol, gelatin, polyvinylpyrrolidone, hydroxyethyl cellulose, glucon, methyl cellulose, sodium dodecylbenzene sulfonate, and sodium lignosulfonate. Further, the inorganic salt is polyvinyl alcohol.

[0056] In some embodiments, in S3 above, the mass percentage of pyridoxal methacrylate is 38% to 49% based on the mass of the oil phase as 100%.

[0057] In some embodiments, in step S3 above, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide. Further, the initiator is azobisisobutyronitrile.

[0058] In some embodiments, in step S5 above, after reacting the suspended dispersion system at 65°C to 75°C for 8 to 12 hours under the protection of a protective gas, post-treatment is also included, which includes sequential cooling, filtration, washing, and drying.

[0059] It is understood that the reaction temperature is between 65℃ and 75℃, for example, 65℃, 68℃, 70℃, 72℃, 75℃, and any value within the range of any two of the above values. Furthermore, the reaction temperature is 70℃.

[0060] The reaction time is 8h to 12h, for example, 8h, 9h, 10h, 11h, 12h, or any value within the range of any two of the above values. Further, the reaction time is 10h.

[0061] In one embodiment, in step S5 above, the protective gas includes one or more of nitrogen, helium, neon, argon, krypton, and xenon. Further, the protective gas is nitrogen.

[0062] The second aspect of this application provides a polymer microsphere prepared using the same method as that provided in the first aspect of this application.

[0063] The third aspect of this application provides the application of the polymer microspheres prepared by the method of the first aspect of this application in the adsorption of uranyl ions in a solution.

[0064] In some implementations, the pH of the solution is 1 to 7.5, for example, 1, 2, 3, 4, 5, 6, 7, 7.5, and any value within the range of any two of the above values.

[0065] Furthermore, this application provides the following specific embodiments and comparative examples to further illustrate the specific implementation of this application and its advantages.

[0066] Example 1

[0067] (1) Preparation of pyridoxal methacrylate: Under nitrogen protection and light-protected conditions, 0.03 mol of pyridoxal was dissolved in 150 mL of anhydrous tetrahydrofuran, and 4.2 mL of triethylamine was added. After cooling to 0 °C in an ice-water bath, 0.03 mol of methacryloyl chloride was slowly added dropwise. After the addition was completed, the mixture was brought back to room temperature for esterification reaction for 12 h. After the esterification reaction was completed, the triethylamine salt was removed by filtration. The filtrate was concentrated by rotary evaporation, and the crude product was purified by silica gel column chromatography (eluent: V(ethyl acetate) / V(petroleum ether) = 1 / 1) to obtain the white solid product pyridoxal methacrylate, denoted as PLMA monomer.

[0068] (2) Preparation of aqueous phase: Dissolve 1.5g of polyvinyl alcohol (PVA-1788) and 0.5g of sodium chloride in 200mL of deionized water, transfer to a four-necked flask, and prepare the aqueous phase for later use.

[0069] (3) Preparation of oil phase: 8.0g of pyridoxal methacrylate monomer, 12.0g of styrene, 0.40g of divinylbenzene and 0.20g of azobisisobutyronitrile are mixed evenly to prepare an oil phase for later use.

[0070] (4) Preparation of suspension dispersion system: After heating the aqueous phase to 70°C, the above oil phase is quickly poured into the aqueous phase under stirring at 400 rpm to prepare the suspension dispersion system.

[0071] (5) Preparation of polymer microspheres: After the suspension dispersion system stabilized, nitrogen gas was introduced, and the suspension dispersion system was reacted at a constant temperature of 70℃ for 10h. After the reaction was completed, the system was cooled, filtered, washed, and dried to prepare polymer microspheres. The polymer microspheres finally prepared were denoted as PLMA-polymer microspheres.

[0072] Example 2

[0073] The preparation process of this embodiment is basically the same as that of Example 1. The main difference is that the molar ratio of pyridoxal (0.03 mol) and methacryloyl chloride (0.027 mol) in step (1) of this embodiment is 1:0.9.

[0074] Example 3

[0075] The preparation process of this embodiment is basically the same as that of Example 1. The main difference is that the molar ratio of pyridoxal 0.03 mol and methacryloyl chloride (0.033 mol) in step (1) of this embodiment is 1:1.1.

[0076] Example 4

[0077] The preparation process of this embodiment is basically the same as that of embodiment 1. The main difference is that in step (3) of this embodiment, the amount of pyridoxal methacrylate monomer added is 9.0g, the amount of styrene added is 11.0g, and the mass percentage of pyridoxal methacrylate is 43.7%.

[0078] Example 5

[0079] The preparation process of this embodiment is basically the same as that of embodiment 1. The main difference is that in step (3) of this embodiment, the amount of pyridoxal methacrylate monomer added is 10.0g, the amount of styrene added is 10.0g, and the mass percentage of pyridoxal methacrylate is 48.5%.

[0080] Comparative Example 1

[0081] The preparation process of this comparative example is basically the same as that of Example 1. The main difference is that step (1) is not included in this comparative example; and step (3) is: 20.0g of styrene, 0.40g of divinylbenzene and 0.20g of azobisisobutyronitrile are mixed evenly to prepare an oil phase for later use.

[0082] Comparative Example 2

[0083] The preparation process of this comparative example is basically the same as that of Example 1. The main difference is that step (1) of this comparative example is as follows: under nitrogen protection, 0.03 mol of nicotinic acid is dissolved in 150 mL of anhydrous tetrahydrofuran, 4.2 mL of triethylamine is added, and after cooling to 0°C in an ice-water bath, 0.03 mol of methacryloyl chloride is slowly added dropwise. After the addition is completed, the mixture is brought back to room temperature for esterification reaction for 12 h. After the esterification reaction is completed, the triethylamine salt is removed by filtration, the filtrate is concentrated by rotary evaporation, and the crude product obtained is purified by silica gel column chromatography (eluent: V(ethyl acetate) / V(petroleum ether) = 1 / 1) to obtain a white solid product, nicotinic acid methacrylate, denoted as NCA monomer.

[0084] Step (3) of the comparative example is as follows: 5.8g of NCA monomer, 14.2g of styrene, 0.40g of divinylbenzene and 0.20g of azobisisobutyronitrile are mixed evenly to prepare an oil phase for later use.

[0085] The polymer microspheres finally prepared are denoted as NCA-polymer microspheres.

[0086] Comparative Example 3

[0087] The preparation process of this comparative example is basically the same as that of Example 1. The main difference is that step (1) of this comparative example is as follows: under nitrogen protection, 0.03 mol of isonicotinic acid is dissolved in 150 mL of anhydrous tetrahydrofuran, 4.2 mL of triethylamine is added, and after cooling to 0°C in an ice-water bath, 0.03 mol of methacryloyl chloride is slowly added dropwise. After the addition is complete, the mixture is brought back to room temperature for esterification reaction for 12 h. After the esterification reaction is completed, the triethylamine salt is removed by filtration, and the filtrate is concentrated by rotary evaporation. The crude product obtained is purified by silica gel column chromatography (eluent: V(ethyl acetate) / V(petroleum ether) = 1 / 1) to obtain a white solid product, isonicotinic acid methacrylate, denoted as INA monomer.

[0088] Step (3) of the comparative example is as follows: 5.8g of INA monomer, 14.2g of styrene, 0.40g of divinylbenzene and 0.20g of azobisisobutyronitrile are mixed evenly to prepare an oil phase for later use.

[0089] The polymer microspheres finally prepared are denoted as ICA-polymer microspheres.

[0090] Comparative Example 4

[0091] Commercially available metamine oxime resin, model number D851.

[0092] Comparative Example 5

[0093] Commercially available iminodiacetic acid resin, model number LSC-600.

[0094] Test case

[0095] (1) Adsorption capacity test of uranyl ions at different pH values.

[0096] A solution with an initial uranium ion concentration of 50 mg / L was prepared, and the pH was adjusted using nitric acid or sodium hydroxide. 20.0 mg of the polymer microspheres or resin provided in the above examples and comparative examples were weighed and placed in 50 mL Erlenmeyer flasks containing the above uranium solution, and incubated at 25°C with shaking for 24 h. The equilibrium concentration was determined by ICP-OES (inductively coupled plasma optical emission spectrometry), and the adsorption capacity (Qe, mg / g) was calculated. The test results are shown in Table 1 below.

[0097] Table 1

[0098]

[0099] As shown in Table 1, although the commercially available amine oxime resin exhibits the highest adsorption capacity at pH 5.0, its adsorption capacity decreases sharply under strong acid (pH 1.0) and weak alkaline (pH 7.5) conditions. The commercially available imine diacetate resin shows low adsorption capacity across the entire pH range.

[0100] The adsorption capacity of NCA-polymer microspheres and INA-polymer microspheres is much lower than that of PLMA-polymer microspheres and amylopyridine resin provided in the embodiments of this application, proving that the coordination ability of a single pyridine ring is limited.

[0101] Meanwhile, the PLMA-polymer microspheres provided in this application exhibit excellent and stable adsorption capacity within a pH range of 1 to 7.5. Particularly in a strongly acidic environment at pH 1.0, its adsorption capacity (42.5 mg / g) is more than 2.6 times that of the amylopyridine resin, and in a weakly alkaline environment at pH 7.5, its capacity (65.3 mg / g) is more than 1.4 times that of the amylopyridine resin. This fully demonstrates that the synergistic coordination between the aldehyde group and pyridine nitrogen in the pyridoxal molecule of the polymer microspheres provided in this application greatly enhances the broad-spectrum pH adaptability to uranyl ions.

[0102] (2) Adsorption selectivity test.

[0103] Under pH=5.0 conditions, a solution containing uranyl ions (10 mg / L) and the competing ion Cu was prepared. 2+ Fe 3+ Ca 2+ and Mg 2+ An adsorption experiment was conducted using the polymer microspheres or resins provided in Examples 1, 2, and 4 above, with a concentration of 10 mg / L for each mixed solution. 50 mL of the mixed solution was taken, and 20 mg of the polymer microspheres or resins provided in Examples 1, 2, and 4 above was added to the mixed solution.

[0104] The formulas for calculating the allocation coefficient (Kd) and the selectivity coefficient (S) are as follows:

[0105] ;

[0106] ;

[0107] Where C0 and Ce are the initial concentration (mg / L) and equilibrium concentration (mg / L) of uranyl ions in the solution, respectively, V is the solution volume (mL), and m is the mass of the adsorbent material (g). The test results are shown in Table 2 below.

[0108] K d (A) and K d (B) are uranyl ions (UO2) 2+ The partition coefficients of the ion (B) and its competing ion (B) are shown in Table 3 below.

[0109] Table 2

[0110]

[0111] Table 3

[0112]

[0113] According to the data in Table 2, the partition coefficient of the polymer microspheres provided in this application for uranyl ions is much higher than that of the materials provided in Comparative Examples 2 and 4. According to the data in Table 3, the selectivity of the polymer microspheres provided in this application for competing ions is also much higher than that of Comparative Examples 2 and 4, which proves that the polymer microspheres provided in this application have good selectivity for uranyl ions.

[0114] (3) Test on the regeneration and reusability of the adsorbent.

[0115] Adsorption-desorption cycle experiments were conducted on the PLMA-polymer microspheres prepared in Example 1.

[0116] Adsorption: 100 mg of PLMA-polymer microspheres were subjected to saturated adsorption at pH 7.0 and an initial uranium concentration of 50 mg / L.

[0117] Desorption / Regeneration: After filtering the saturated adsorbent, transfer it to a 0.1 mol / L sodium carbonate (Na2CO3) solution and shake at 25°C for 4 h.

[0118] Washing: After desorption, the polymer microspheres were collected by filtration and thoroughly washed with deionized water until neutral, ready for the next round of use. The above process was repeated 5 times, and the uranium adsorption capacity was recorded for each cycle. The test results are shown in Table 4 below.

[0119] Table 4

[0120]

[0121] As shown in Table 4, after 5 adsorption-desorption cycles, the adsorption capacity retention rate of PLMA-polymer microspheres is still above 90%, indicating that the polymer microsphere adsorbent provided in this application has excellent regeneration performance and structural stability, and excellent cycle performance.

[0122] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing polymer microspheres, characterized in that, Includes the following steps: Under protective gas and light-protected conditions, pyridoxal, anhydrous aprotic polar solvent, organic base and methacryloyl chloride were mixed and subjected to esterification reaction to prepare pyridoxal methacrylate. An aqueous phase is prepared by dissolving inorganic salts and dispersants in water; The pyridoxal methacrylate, styrene, divinylbenzene, and initiator are mixed to prepare an oil phase; After heating the aqueous phase to 65℃~75℃, the oil phase is added to the aqueous phase under stirring conditions to prepare a suspension dispersion system; The polymer microspheres were prepared by reacting the suspension dispersion system at 65℃~75℃ for 8h~12h under the protection of a protective gas.

2. The method for preparing polymer microspheres according to claim 1, characterized in that, The steps for preparing pyridoxal methacrylate include: Under protective gas and light-protected conditions, the organic base is added to the anhydrous aprotic polar solvent in which the pyridoxal is dissolved, cooled to -10°C to 10°C, and then the methacryloyl chloride is added dropwise. The esterification reaction is carried out at room temperature to prepare the pyridoxal methacrylate.

3. The method for preparing polymer microspheres according to claim 1 or 2, characterized in that, The steps for preparing pyridoxal methacrylate must satisfy at least one of the following conditions: (1) The molar ratio of pyridoxal to methacryloyl chloride is 1:(0.9~1.1); (2) The anhydrous aprotic polar solvent includes one or more of anhydrous tetrahydrofuran, anhydrous dichloromethane, and anhydrous diethyl ether; (3) The organic base includes one or more of triethylamine, tri-n-butylamine, tri-n-pentylamine, tripropylamine and N,N-diisopropylethylamine.

4. The method for preparing polymer microspheres according to claim 1 or 2, characterized in that, The esterification reaction step is followed by a purification process, which includes sequential filtration, concentration of the filtrate, and column chromatography separation.

5. The method for preparing polymer microspheres according to claim 1 or 2, characterized in that, The steps for preparing the aqueous phase must satisfy at least one of the following conditions: (1) The inorganic salts include one or more of sodium chloride, sodium phosphate, sodium dihydrogen phosphate, sodium monohydrogen phosphate, and sodium carbonate; (2) The dispersant includes one or more of polyvinyl alcohol, gelatin, polyvinylpyrrolidone, hydroxyethyl cellulose, glucon, methyl cellulose, sodium dodecylbenzene sulfonate and sodium lignosulfonate.

6. The method for preparing polymer microspheres according to claim 1 or 2, characterized in that, The steps for preparing the oil phase must satisfy at least one of the following conditions: (1) Based on the mass of the oil phase as 100%, the mass percentage of the pyridoxal methacrylate is 38%~49%; (2) The initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide.

7. The method for preparing polymer microspheres according to claim 1 or 2, characterized in that, Under the protection of a protective gas, the suspended dispersion system is reacted at 65℃~75℃ for 8h~12h, followed by post-treatment, which includes sequential cooling, filtration, washing and drying.

8. A polymer microsphere, characterized in that, The polymer microspheres were prepared using the method described in any one of claims 1-7.

9. The application of the polymer microspheres prepared by the method according to any one of claims 1-7 in the adsorption of uranyl ions in a solution.

10. The application according to claim 9, characterized in that, The pH of the solution is 1 to 7.5.

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