Preparation method and application of cyclodextrin polymer composite adsorption material

Abstract

The application discloses a preparation method and application of a cyclodextrin polymer composite adsorbing material. The preparation method of the adsorbing material comprises the following steps: under the action of NaH, β-cyclodextrin is subjected to hydroxyl activation, then maleic anhydride is slowly added to carry out a reaction, and thus a β-cyclodextrin-dibutenedioic acid ester derivative is prepared; under the action of an initiator and a crosslinking agent, the β-cyclodextrin-dibutenedioic acid ester, a double-bond-containing monomer and a functional monomer are subjected to a polymerization reaction, and then are washed and dried, so as to obtain the cyclodextrin polymer composite adsorbing material; the functional monomer is silanized montmorillonite or Fe3O4-dibutenedioic acid ester; and the double-bond-containing monomer is one of acrylic acid, acrylamide and styrene. The cyclodextrin polymer composite adsorbing material with multiple action sites is prepared by using β-cyclodextrin and the functional monomer as raw materials, and by utilizing the structural advantages of different compounds; the preparation conditions of the obtained composite material are mild, the post-treatment is simple, and the composite material has high adsorbing efficiency as an adsorbent.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a cyclodextrin polymer composite adsorbent material, belonging to the field of cyclodextrin polymer functional material preparation. Background Technology

[0002] Cyclodextrins (CDs) are macrocyclic oligosaccharide compounds composed of multiple α-1,4-glycosidic bonds. They possess a hydrophobic cavity structure, allowing them to encapsulate many hydrophobic small molecules. Therefore, since their discovery by Villiers in 1891, CDs have been widely used in food, pharmaceutical delivery, the chemical industry, and environmental engineering. However, the water solubility and single site of action of natural cyclodextrins often limit their practical applications. Therefore, given the structural characteristic of multiple hydroxyl groups surrounding the cavities of cyclodextrins, many cyclodextrins have been modified with different groups to form various cyclodextrin derivatives. Furthermore, these cyclodextrin derivatives can undergo bulk polymerization, copolymerization, or immobilization to form polymeric derivatives containing multiple cyclodextrin units, thereby expanding the application range of cyclodextrins.

[0003] Montmorillonite is a layered non-metallic mineral containing aluminosilicates and is the main component of natural bentonite. Montmorillonite possesses a large specific surface area, abundant pore structure, and adjustable interlayer spacing, exhibiting strong adsorption and ion exchange capabilities. Furthermore, its abundant and readily available reserves make it a promising candidate for wastewater purification through pollutant adsorption. However, natural montmorillonite suffers from low affinity for organic pollutants and poor selective adsorption of metal ions, limiting its direct use. Organic modification of montmorillonite can enhance its adsorption performance and expand its application range.

[0004] Ferric oxide (Fe3O4), a magnetic material, is mainly composed of tetrahedral and octahedral structural units, characterized by its small size and large specific surface area. Furthermore, ferric oxide exhibits magnetic response surface effects and superparamagnetism, allowing it to rapidly aggregate and precipitate under an external magnetic field. Through modification and polymerization with cyclodextrin to form adsorbent materials, it can effectively improve or even overcome the problem of difficult adsorbent separation.

[0005] In view of this, the present invention combines the structural characteristics of cyclodextrin polymers, montmorillonite, and iron oxide to provide a method for preparing cyclodextrin polymer composite adsorbent materials and their applications. Summary of the Invention

[0006] This invention aims to provide a method for preparing and applying a cyclodextrin polymer composite adsorbent material. Using inexpensive and readily available β-cyclodextrin and functional monomers as raw materials, the method leverages the structural advantages of different compounds to provide a method for preparing a cyclodextrin polymer composite adsorbent material with multiple active sites. The resulting composite material is prepared under mild conditions, has simple post-processing, and exhibits high adsorption efficiency as an adsorbent.

[0007] The cyclodextrin polymer composite adsorbent materials provided by the method of this invention include montmorillonite / cyclodextrin polymer composite adsorbent materials and Fe3O4 / cyclodextrin polymer composite adsorbent materials. Both share the following characteristics: the resulting composite materials have rough, porous surfaces rich in -OH, -NH2, -COOH, -Ph, and -C=O, which not only enriches the active sites for adsorption such as hydrogen bonding, electrostatic interactions, π-π interactions, and dipole interactions, but also, under the action of NaH, undergo an esterification reaction with maleic anhydride and cyclodextrin, resulting in β-cyclodextrin-dibutenoate, which is mainly a monosubstituted product, effectively preserving the cavity structure of cyclodextrin and providing cavity inclusion sites. Based on this, a composite adsorbent material was obtained using silanized montmorillonite as a functional monomer. The cyclodextrin polymer exists as an interlayer in the middle of the montmorillonite and is immobilized on the surface of the montmorillonite, providing adsorption capacity and exhibiting good adsorption effect on dye molecules or metal ions. A composite adsorbent material obtained using Fe3O4-dibutenoate as a functional monomer has a magnetic, rough, porous structure, which not only increases the hydrogen bonding and electrostatic interaction sites in the adsorbent material, but also improves the problem of the adsorbent being difficult to separate.

[0008] This invention provides a method for preparing a cyclodextrin polymer composite adsorbent material, comprising the following steps:

[0009] (1) β-Cyclodextrin was activated by NaH, and then maleic anhydride was slowly added to react. After treatment with acetone, β-Cyclodextrin-dibutenoate derivative was obtained.

[0010] (2) Under the action of initiator and crosslinking agent, β-cyclodextrin-dibutenoate, double bond monomer and functional monomer are reacted at 50~80℃ for 8~24 h, then washed repeatedly with anhydrous ethanol and water, and vacuum dried to obtain cyclodextrin polymer composite adsorbent material.

[0011] The functional monomer is silanized montmorillonite or Fe3O4-dibutenoate.

[0012] In the above method, the monomer containing double bonds is one of acrylic acid, acrylamide, and styrene.

[0013] When the functional monomer is silanized montmorillonite, the specific preparation process is as follows:

[0014] (1) Under acidic conditions, montmorillonite was added to an ethanol / water solution containing silane coupling agent KH-560 and refluxed for 24 hours. The product was washed repeatedly with anhydrous ethanol to obtain silanized montmorillonite.

[0015] (2) β-Cyclodextrin was dissolved in N,N-dimethylformamide, and then the hydroxyl groups were activated by NaH for 24 h. Maleic anhydride was then slowly added and reacted at 25~130℃ for 12~48 h. After treatment with acetone, β-Cyclodextrin-dibutenoate derivative was obtained.

[0016] (3) Under the action of initiator and crosslinking agent, β-cyclodextrin-dibutenoate, monomers containing double bonds and silanized montmorillonite are reacted at 50~80℃ for 8~12 h, and then washed repeatedly with anhydrous ethanol and water, and dried under vacuum to obtain montmorillonite / cyclodextrin polymer composite adsorbent material.

[0017] The preparation process of the above-mentioned montmorillonite / cyclodextrin polymer composite adsorbent material is further explained as follows:

[0018] In step (1), the volume ratio of ethanol to water is 1:1 to 12:1; the acidic condition is achieved by adjusting the pH to 4 with acetic acid. In step (2), the mass ratio of the solvent N,N-dimethylformamide to cyclodextrin is 16.7:1; the molar ratio of β-cyclodextrin to NaH is 1:1 to 1:10; and the molar ratio of β-cyclodextrin to maleic anhydride is 1:1 to 1:11. In step (3), the mass ratio of β-cyclodextrin-dibutenoate to silanized montmorillonite is 2:1 to 1:4. Further, the crosslinking agent used in step (3) is N,N-methylenebisacrylamide, and the amount used is 10% of the mass percentage of the double bond monomer. Furthermore, when β-cyclodextrin-dibutenoate reacts with acrylic acid, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 30–80°C, and the reaction time is 5–24 h; the molar ratio of β-cyclodextrin-dibutenoate to acrylic acid is 1:10–1:30, and the amounts of sodium bisulfite and potassium persulfate used as initiators are 0.2%–2% of the molar amount of acrylic acid, respectively. Furthermore, when β-cyclodextrin-dibutenoate reacts with acrylamide, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 30–80°C, and the reaction time is 5–24 h; the molar ratio of β-cyclodextrin-dibutenoate to acrylamide is 1:10–1:30, and the amounts of sodium bisulfite and potassium persulfate used as initiators are 0.2%–2% of the molar amount of acrylamide, respectively. Furthermore, when β-cyclodextrin-dibutenoate reacts with styrene, the initiator used is benzoyl peroxide, the solvent is benzene, the reaction temperature is 80℃, and the reaction time is 4~24h; the mass ratio of β-cyclodextrin-dibutenoate to styrene is 1:1~1:5, and the amount of benzoyl peroxide initiator is 0.1%~3% of the molar amount of styrene.

[0019] When the functional monomer is Fe3O4-dibutenoate, the specific preparation process is as follows:

[0020] (1) Fe3O4 was dispersed in N,N-dimethylformamide, and then activated with NaH for 24 h. Maleic anhydride was then slowly added and reacted at 25~130℃ for 12~48 h. Fe3O4-dibutenoate was obtained after treatment with acetone.

[0021] (2) β-Cyclodextrin was dissolved in N,N-dimethylformamide, and then the hydroxyl groups were activated by NaH for 24 h. Maleic anhydride was then slowly added and reacted at 25~130℃ for 12~48 h. After treatment with acetone, β-Cyclodextrin-dibutenoate derivative was obtained.

[0022] (3) Under the action of initiator and crosslinking agent, β-cyclodextrin-dibutenoate, monomers containing double bonds and Fe3O4-dibutenoate are reacted at 50~80℃ for 8~24 h, then washed repeatedly with anhydrous ethanol and water, and dried under vacuum to obtain Fe3O4 / cyclodextrin polymer composite adsorbent material.

[0023] The preparation process of the above-mentioned Fe3O4 / cyclodextrin polymer composite adsorbent material is further explained as follows:

[0024] In step (1), the mass ratio of the solvent N,N-dimethylformamide to Fe3O4 is 30.7:1, the molar ratio of Fe3O4 to NaH is 1:2 to 1:12, and the molar ratio of Fe3O4 to maleic anhydride is 1:1 to 1:10. In step (2), the mass ratio of the solvent N,N-dimethylformamide to cyclodextrin is 16.7:1; the molar ratio of β-cyclodextrin to NaH is 1:1 to 1:10, and the molar ratio of β-cyclodextrin to maleic anhydride is 1:1 to 1:11. In step (3), the mass ratio of β-cyclodextrin-dibutenoate to Fe3O4-dibutenoate is 4:1 to 1:4. Further, the crosslinking agent used in step (3) is N,N-methylenebisacrylamide, and the amount used is 5% to 15% of the mass percentage of the double bond monomer. Furthermore, when β-cyclodextrin-dibutenoate reacts with acrylic acid, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 30–80°C, and the reaction time is 5–24 h; the molar ratio of β-cyclodextrin-dibutenoate to acrylic acid is 1:10–1:30, and the amounts of sodium bisulfite and potassium persulfate used as initiators are 0.2%–2% of the molar amount of acrylic acid, respectively. Furthermore, when β-cyclodextrin-dibutenoate reacts with acrylamide, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 30–80°C, and the reaction time is 5–24 h; the molar ratio of β-cyclodextrin-dibutenoate to acrylamide is 1:10–1:30, and the amounts of sodium bisulfite and potassium persulfate used as initiators are 0.2%–2% of the molar amount of acrylamide, respectively. Furthermore, when β-cyclodextrin-dibutenoate reacts with styrene, the initiator used is benzoyl peroxide, the solvent is benzene, the reaction temperature is 80℃, and the reaction time is 4~24h; the mass ratio of β-cyclodextrin-dibutenoate to styrene is 1:1~1:5, and the amount of benzoyl peroxide initiator is 0.1%~3% of the molar amount of styrene.

[0025] This invention provides a cyclodextrin polymer composite adsorbent material prepared by the above-described method.

[0026] This invention provides the application of the above-mentioned cyclodextrin polymer composite adsorbent material in the adsorption of organic dye molecules.

[0027] The specific application process is as follows: Weigh 10 mg of cyclodextrin polymer composite adsorbent material and add it to 20 mL of dye solution. Adsorption is carried out by magnetic stirring at 800 rpm. After adsorption, the supernatant is collected after centrifugation. The absorbance A at its maximum absorption wavelength is measured by ultraviolet spectrophotometer. The dye concentration is calculated according to the standard curves corresponding to each dye. Then, the amount of methylene blue adsorbed at different times is calculated.

[0028] In the above adsorption process, the concentration of dye used is 10~400 mg / L; the adsorption time is 15~250 min, and the time gradient is set to take samples every 15 min; the pH of the adsorbed dye solution is 3~11; and the adsorption temperature is 10~40℃.

[0029] The adsorption equilibrium time for methylene blue provided by this invention is 150 min, the maximum adsorption capacity is 475.86 mg / g, and the removal rate is 91.51%. Alkaline conditions are more favorable for the adsorption of methylene blue by the β-cyclodextrin-acrylic polymer / montmorillonite. Increased temperature promotes faster molecular motion and increases the adsorption capacity, but excessively high temperatures are detrimental to adsorption.

[0030] The adsorption equilibrium times for methylene blue of the cyclodextrin-acrylic acid / Fe3O4, cyclodextrin-acrylamide / Fe3O4, and cyclodextrin-styrene / Fe3O4 composite materials provided by this invention were 120 min, 90 min, and 120 min, respectively, with equilibrium adsorption capacities of 39.50 mg / g, 24.36 mg / g, and 20.86 mg / g, respectively. All three materials exhibited better adsorption performance under alkaline conditions.

[0031] The beneficial effects of this invention are:

[0032] (1) The raw materials used in this invention are β-cyclodextrin, montmorillonite or Fe3O4, all of which are inexpensive, readily available and have low toxicity;

[0033] (2) The preparation process provided by the present invention is mild, with a maximum temperature not exceeding 80°C, and the post-processing is simple and easy to operate, which is conducive to realizing large-scale industrial production;

[0034] (3) Modifying montmorillonite with silane can widen the interlayer spacing of montmorillonite, which is beneficial for polymer intercalation and improves its adsorption capacity. This technology overcomes the weakness of natural montmorillonite's adsorption capacity and also combines the structural characteristics of cyclodextrin, enriching the types of adsorbents. The cyclodextrin polymer / montmorillonite composite material prepared by this invention has a rough and porous surface, which has a good adsorption effect on dye molecules and can also be used for the adsorption of metal ions.

[0035] (4) Modify magnetic iron oxide into a compound with double bonds, and use it as an active monomer to copolymerize with cyclodextrin to obtain a magnetic rough and porous composite material. This not only increases the hydrogen bond and electrostatic interaction sites in the adsorbent material, but also improves the problem of the adsorbent being difficult to separate. Attached Figure Description

[0036] Figure 1 The infrared spectrum of the β-cyclodextrin-dibutenoate prepared in Example 2.

[0037] Figure 2 The infrared spectrum of the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material prepared in Example 3 is shown.

[0038] Figure 3 The image shows a SEM image of the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material prepared in Example 3.

[0039] Figure 4 This is the standard working curve for methylene blue.

[0040] Figure 5 The graph shows the change in the adsorption capacity of methylene blue by the β-cyclodextrin-acrylic polymer / montmorillonite composite material in Example 6 over the adsorption time.

[0041] Figure 6 This is a graph showing the adsorption data of methylene blue for the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material in Example 6 at different pH values.

[0042] Figure 7 The graph shows the adsorption data of methylene blue for the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material in Example 6 at different temperature values.

[0043] Figure 8 This is a graph showing the repeatability of methylene blue adsorption data for the β-cyclodextrin-acrylic polymer / montmorillonite composite material in Example 6.

[0044] Figure 9 The infrared spectrum of Fe3O4-dibutenoate prepared in Example 7.

[0045] Figure 10 The infrared spectrum of cyclodextrin / Fe3O4 composite materials formed by β-cyclodextrin and different monomers containing double bonds.

[0046] Figure 11 The image shows a SEM image of the cyclodextrin-acrylic acid / Fe3O4 composite material prepared in Example 8.

[0047] Figure 12 The image shows a SEM image of the cyclodextrin-acrylamide / Fe3O4 composite material prepared in Example 8.

[0048] Figure 13 The image shows a SEM image of the cyclodextrin-styrene / Fe3O4 composite material prepared in Example 8.

[0049] Figure 14 This is a graph showing the adsorption time of the cyclodextrin-acrylic acid / Fe3O4 composite material for the amount of methylene blue in Example 11.

[0050] Figure 15 This is a graph showing the adsorption time of the cyclodextrin-acrylamide / Fe3O4 composite material for the amount of methylene blue in Example 11.

[0051] Figure 16 This is a graph showing the adsorption time of the cyclodextrin-styrene / Fe3O4 composite material for the amount of methylene blue in Example 11.

[0052] Figure 17 The graph shows the adsorption data of methylene blue by the cyclodextrin-acrylic acid / Fe3O4 composite material in Example 11 at different pH values.

[0053] Figure 18 The graph shows the adsorption data of methylene blue by the cyclodextrin-acrylamide / Fe3O4 composite material in Example 11 at different pH values.

[0054] Figure 19 This is a graph showing the adsorption data of methylene blue for the cyclodextrin-styrene / Fe3O4 composite material in Example 11 at different pH values.

[0055] Figure 20 This is a graph showing the repeatability of methylene blue adsorption data for the cyclodextrin-acrylic acid / Fe3O4 composite material in Example 11. Detailed Implementation

[0056] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments.

[0057] Example 1: Organic Modification of Montmorillonite

[0058] In a round-bottom flask, 7g of silane coupling agent KH560 was added to a 100mL ethanol / distilled water (9 / 1) mixed solution, and an appropriate amount of acetic acid was added to adjust the pH of the solution to 4. After stirring for 4 hours, 10g of montmorillonite was added to the hydrolyzed solution, and the mixture was refluxed at 70℃ for 24 hours. Finally, the treated montmorillonite product was diluted with a large amount of anhydrous ethanol, washed, filtered, and then vacuum dried at 90℃ for 24 hours to obtain silanized montmorillonite.

[0059] Example 2: Preparation of β-cyclodextrin-dibutenoate

[0060] Weigh 2.27 g of β-CD and place it in a 100 mL single-necked flask. Add 40 mL of N,N-dimethylformamide and stir with a magnetic stirrer until completely dissolved. Weigh 0.48 g of NaH and slowly add it to the solution with vigorous stirring. Continue stirring at room temperature for 24 h. Weigh 1.372 g of maleic anhydride and slowly add it to the above solution. The solution turns pale yellow. Continue stirring for 48 h and then stop the reaction. Treat the resulting solution with acetone and dry it in a vacuum drying oven at 30 °C to obtain a white or pale yellow solid powder, which is β-cyclodextrin-dibutenoate.

[0061] Figure 1 The image shows the infrared spectrum of β-cyclodextrin-dibutenoate. As can be seen from the image, at 1722.53 cm⁻¹... -1 The characteristic absorption peak of C=O appeared at 1584.55 cm⁻¹. -1 The characteristic absorption peak of C=C appeared at 1425.89 cm⁻¹. -1 The characteristic absorption peak of the double bond CH appeared at 3383.91 cm⁻¹. -1 The characteristic absorption peak at this point indicates that β-cyclodextrin-dibutenoate was successfully synthesized.

[0062] Example 3: β-Cyclodextrin-Acrylic Polymer / Montmorillonite Composite Material

[0063] 2.1 g of β-cyclodextrin-dibutyl ester (prepared in Example 2) and 4.2 g of silanized montmorillonite (prepared in Example 1) were added to a 100 mL single-necked flask. After thorough mixing with 50 mL of water, the mixture was heated to 50 °C. 0.0718 g of potassium persulfate and 0.0277 g of sodium bisulfite were added to the solution, and the mixture was stirred for 5 min. Then, 2.4 mL of acrylic acid and 0.24 g of crosslinking agent N,N-dimethylformamide were added to the reaction solution, and the reaction was continued for 12 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and water, respectively, and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material.

[0064] Figure 2 The image shows the infrared spectrum of the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material. From the image, we can see that the wavelength is 3629.89 cm⁻¹. -1 The absorption peak for -OH in montmorillonite lamellae is located at 3417.17 cm⁻¹. -1 This corresponds to the vibrational absorption peak of -OH in the cyclodextrin polymer, at 1737.79 cm⁻¹. -1 The characteristic absorption peak for C=O is at 1028.02 cm⁻¹. -1 It is the absorption peak of Si-O-Si, at 520.76 cm⁻¹. -1 464.83cm-1 The presence of a unique vibrational absorption peak in Si-O-Al indicates the successful synthesis of the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material.

[0065] Figure 3 The image shows a SEM image of the β-cyclodextrin-acrylic acid polymer / montmorillonite composite material. The image shows that the composite has a rough, porous structure, which is beneficial for adsorption applications.

[0066] Example 4: Cyclodextrin-acrylamide polymer / montmorillonite composite material

[0067] 2.1 g of β-cyclodextrin-dibutyl ester and 4.2 g of silanized montmorillonite were added to a 100 mL single-necked flask. After thorough mixing with 50 mL of water, the mixture was heated to 50 °C. 0.0567 g of potassium persulfate and 0.0218 g of sodium bisulfite were then added to the solution. After stirring for 5 min, 1.89 g of acrylamide and 0.189 g of crosslinking agent N,N-dimethylformamide were added to the reaction solution, and the reaction was continued for 12 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and water, respectively, and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-acrylamide polymer / montmorillonite composite material.

[0068] Example 5: Cyclodextrin-styrene polymer / montmorillonite composite material

[0069] 2.1 g of β-cyclodextrin-dibutyl acrylate and 4.2 g of silanized montmorillonite were added to a 100 mL single-necked flask. After thorough mixing with 40 mL of benzene, the mixture was heated to 80 °C. Then, 0.1222 g of benzoyl peroxide was added as an initiator, and the mixture was stirred for 5 min. Next, 5.8 mL of styrene and 0.525 g of N,N-dimethylformamide, a crosslinking agent, were added to the reaction solution, and the reaction was continued for 8 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-styrene polymer / montmorillonite composite material.

[0070] Example 6: Adsorption application of β-cyclodextrin-acrylic polymer / montmorillonite composite material

[0071] This invention preferably uses methylene blue as the adsorbed dye, providing an adsorption effect for the β-cyclodextrin-acrylic polymer / montmorillonite composite material.

[0072] Standard working curve for methylene blue: Weigh 100 mg of methylene blue dye into a 100 mL volumetric flask, add water to the 100 mL mark to prepare a 1000 mg / L solution. Pipette different volumes of this solution into 10 mL volumetric flasks to prepare methylene blue solutions with concentration gradients of 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, and 70 mg / L. Measure the absorbance of the solutions at an absorption wavelength of 661 nm. Plot a concentration-absorbance standard curve based on the absorbance A corresponding to concentration C, see [reference needed]. Figure 4 As shown.

[0073] Effect of adsorption time on adsorption capacity: 10 mg of β-cyclodextrin-acrylic acid polymer / montmorillonite composite material was weighed and added to 20 mL of dye solution (260 mg / L). Adsorption was carried out by magnetic stirring at 800 rpm, with a time gradient of sampling every 15 min. After centrifugation, the supernatant was collected, and the absorbance A at its maximum absorption wavelength was measured by UV spectrophotometer. The dye concentration was calculated based on the standard curves corresponding to each dye, and then the methylene blue adsorption capacity at different times was calculated. The experimental results are shown in [Figure number missing]. Figure 5 As can be seen from the figure, the adsorption equilibrium time of β-cyclodextrin-acrylic acid polymer / montmorillonite for methylene blue was 150 min, the maximum adsorption capacity was 475.86 mg / g, and the removal rate was 91.51%.

[0074] Effect of solution pH on adsorption capacity: 10 mg of β-cyclodextrin-acrylic acid polymer / montmorillonite adsorbent was weighed and added to 20 mL (260 mg / L) dye solutions at pH values ​​of 3, 5, 7, 9, and 11, respectively. The solutions were stirred at room temperature for 150 min. After adsorption, the supernatant was collected by high-speed centrifugation in centrifuge tubes, and its absorbance was measured using a UV-Vis spectrophotometer. The concentration corresponding to the absorbance value was calculated using a standard curve. Based on the calculated methylene blue adsorption capacity at different pH values, a curve showing the relationship between adsorption capacity and pH was plotted. Figure 6 As can be seen from the figure, alkaline conditions are more favorable for the adsorption of methylene blue by cyclodextrin-acrylic acid polymer / montmorillonite, because there are more -O groups in an alkaline environment. - It increases the electrostatic interaction with methylene blue.

[0075] Effect of adsorption temperature on adsorption capacity: 10 mg of β-cyclodextrin-acrylic acid polymer / montmorillonite adsorbent was weighed and added to 20 mL (260 mg / L) dye solutions at temperatures of 10℃, 20℃, 30℃, and 40℃, respectively, and stirred for 150 min at room temperature. After adsorption, the supernatant was collected by high-speed centrifugation in centrifuge tubes, and its absorbance was measured by UV-Vis spectrophotometer. The concentration corresponding to the absorbance value was calculated using a standard curve. Based on the calculated methylene blue adsorption capacity at different temperature values, the relationship curve between adsorption capacity and temperature was plotted, as shown in [reference needed]. Figure 7 As can be seen from the figure, higher temperatures are beneficial for accelerating molecular motion and increasing the amount of adsorption, but excessively high temperatures are detrimental to adsorption.

[0076] Repeatability test of β-cyclodextrin-acrylic polymer / montmorillonite: Eluent containing a mixture of ethanol and acetic acid (v:v = 20:1) was used to elute the β-cyclodextrin-acrylic polymer / montmorillonite composite material adsorbed with methylene blue. The eluted and dried composite material was then used to re-adsorb methylene blue. After five repeatability tests, the adsorption rate of methylene blue by the β-cyclodextrin-acrylic polymer / montmorillonite composite material remained above 95%, indicating good reproducibility and practicality. The experimental results are shown in [Figure number missing]. Figure 8 .

[0077] Example 7: Preparation of Fe3O4-dibutenoate

[0078] 0.926 g of Fe3O4 was weighed and placed in a 100 mL single-necked flask. 30 mL of N,N-dimethylformamide was added, and the mixture was stirred with a magnetic stirrer to ensure even distribution in the solution. 0.96 g of NaH was weighed and slowly added to the solution with vigorous stirring, and the mixture was stirred continuously at room temperature for 24 hours. 2.744 g of maleic anhydride was then weighed and slowly added to the solution in a round-bottom flask, and the reaction mixture was stirred continuously. The reaction was continued at room temperature for another 24 hours. After the reaction was complete, the mixture was filtered, and the filter cake was washed five times with copious amounts of acetone. Finally, it was dried at 30 °C to obtain Fe3O4-dibutenoate.

[0079] Figure 9 The infrared spectrum of Fe3O4-dibutenoate shows that: 578 cm⁻¹ -1 The characteristic absorption peak of Fe-O is present at 3421 cm⁻¹. -1 The characteristic absorption peak of -OH is present at 1585.57 cm⁻¹. -1 The peak at 1745 cm⁻¹ indicates the presence of a characteristic C=C absorption peak in the product; -1 The presence of a characteristic absorption peak at C=O indicates that Fe3O4-dibutenoate was successfully synthesized.

[0080] Example 8: Preparation of β-cyclodextrin-acrylic acid / Fe3O4 composite material

[0081] 3 g of β-cyclodextrin-dibutenoate (prepared in Example 2) and 1.8 g of Fe3O4-dibutenoate (prepared in Example 7) were added to a 100 mL single-necked flask. After thorough mixing with 50 mL of water, the mixture was heated to 50 °C. 0.2052 g of potassium persulfate and 0.0792 g of sodium bisulfite were then added to the solution. After stirring for 5 min, 6.86 mL of acrylic acid and 0.5 g of crosslinking agent N,N-dimethylformamide were added to the reaction solution, and the reaction was continued for 24 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and water, respectively, and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-acrylic acid / Fe3O4 composite material.

[0082] Example 9: β-Cyclodextrin-Acrylamide / Fe3O4 Composite Material

[0083] 3 g of β-cyclodextrin-dibutenoate (prepared in Example 2) and 1.8 g of Fe3O4-dibutenoate (prepared in Example 7) were added to a 100 mL single-necked flask. After thorough mixing with 50 mL of water, the mixture was heated to 50 °C. 0.1599 g of potassium persulfate and 0.0615 g of sodium bisulfite were added to the solution, and the mixture was stirred for 5 min. Then, 5.331 g of acrylamide and 0.5 g of crosslinking agent N,N-dimethylformamide were added to the reaction solution, and the reaction was continued for 24 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and water, respectively, and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-acrylamide / Fe3O4 composite material.

[0084] Example 10: β-Cyclodextrin-Styrene / Fe3O4 Composite Material

[0085] 3 g of β-cyclodextrin-dibutenoate (prepared in Example 2) and 1.8 g of Fe3O4-dibutenoate (prepared in Example 7) were added to a 100 mL single-necked flask. After thorough mixing with 50 mL of benzene, the mixture was heated to 80 °C. 0.1812 g of benzoyl peroxide, the initiator, was added to the solution, and the mixture was stirred for 5 min. Then, 8.6 mL of styrene and 0.5 g of N,N-dimethylformamide, the crosslinking agent, were added to the reaction solution, and the reaction was continued for 8 h. After the reaction was complete, the product was washed three times with anhydrous ethanol and dried under vacuum at 70 °C for 24 h to obtain the β-cyclodextrin-styrene / Fe3O4 composite material.

[0086] Figure 10 The image shows the infrared spectra of cyclodextrin / Fe3O4 composites formed by β-cyclodextrin and different monomers containing double bonds. As can be seen from the image, for the cyclodextrin-acrylic acid / Fe3O4 composite, the wavelength at 3376 cm⁻¹ is [missing value]. -1The peaks at 2920 and 2805 cm⁻¹ are characteristic absorption peaks of hydroxyl groups. -1 The nearby peak is a characteristic absorption peak of -CH2- at 1722 cm⁻¹. -1 The characteristic peak of carboxylic acid appeared at 1155 cm⁻¹. -1 The characteristic peak of COC appeared at 1400 cm⁻¹; -1 The absence of symmetrical stretching absorption peaks indicates that the cyclodextrin-acrylic acid / Fe3O4 composite material was successfully synthesized.

[0087] For cyclodextrin-acrylamide / Fe3O4 composites, 3372 cm⁻¹ -1 The peaks at 2939 and 2830 cm⁻¹ are characteristic absorption peaks of hydroxyl groups. -1 The nearby peak is a characteristic absorption peak of -CH2- at 1720 cm⁻¹. -1 The characteristic peak of carboxylic acid appeared at 1640 cm⁻¹. -1 The absorption peak at 1165 cm⁻¹ represents the vibrational absorption peak of the primary amine group. -1 The presence of the characteristic peak of COC indicates that the cyclodextrin-acrylamide / Fe3O4 composite material was successfully synthesized.

[0088] For β-cyclodextrin-styrene / Fe3O4 composites, at 3383 cm⁻¹ -1 The peaks at 2920 and 2811 cm⁻¹ are characteristic absorption peaks of hydroxyl groups. -1 The nearby peak is a characteristic absorption peak of -CH2- at 1714 cm⁻¹. -1 Characteristic peaks of carboxylic acids appeared at 1615 and 1545 cm⁻¹. -1 This is the absorption peak for benzene ring skeletal vibration, at 1428 cm⁻¹. -1 COO - The absorption peak of the symmetric stretching vibration is at 1155 cm⁻¹. -1 The presence of the characteristic peak of COC indicates that the cyclodextrin-styrene / Fe3O4 composite material was successfully synthesized.

[0089] Figures 11-13 The images show SEM images of the cyclodextrin-acrylic acid / Fe3O4 composite material, the cyclodextrin-acrylamide / Fe3O4 composite material, and the cyclodextrin-styrene / Fe3O4 composite material, respectively. It can be seen from the images that the composite material prepared with acrylic acid and acrylamide as monomers is a porous material with a compact structure and a rough surface, while the composite material prepared with styrene as monomer has a loose and porous structure with a larger pore size.

[0090] Example 11: Adsorption application of β-cyclodextrin and Fe3O4 composite materials

[0091] This invention preferably uses methylene blue as the adsorbed dye and provides adsorption application effects for cyclodextrin-acrylic acid / Fe3O4 composite materials, cyclodextrin-acrylamide / Fe3O4 composite materials, and cyclodextrin-styrene / Fe3O4 composite materials.

[0092] Figure 4 A standard working curve for methylene blue is provided.

[0093] Effect of adsorption time on adsorption capacity: 10 mg of cyclodextrin-acrylic acid / Fe3O4, cyclodextrin-acrylamide / Fe3O4, and cyclodextrin-styrene / Fe3O4 composites were weighed and added to 20 mL of dye solution (20 mg / L). Adsorption was carried out by magnetic stirring at 800 rpm, with a time gradient of sampling every 15 min. After centrifugation, the supernatant was collected, and the absorbance A at the maximum absorption wavelength was measured using a UV spectrophotometer. The dye concentration was calculated based on the corresponding standard curves for each dye, and then the methylene blue adsorption capacity at different times was calculated. The experimental results are shown in [Figure number missing]. Figures 14-16 As can be seen from the figure, the adsorption equilibrium times of methylene blue for the cyclodextrin-acrylic acid / Fe3O4, cyclodextrin-acrylamide / Fe3O4 and cyclodextrin-styrene / Fe3O4 composite materials are 120 min, 90 min and 120 min, respectively, and the adsorption amounts are 39.50 mg / g, 24.36 mg / g and 20.86 mg / g, respectively.

[0094] Effect of solution pH on adsorption capacity: 10 mg of cyclodextrin-acrylic acid / Fe3O4, cyclodextrin-acrylamide / Fe3O4, and cyclodextrin-styrene / Fe3O4 composite materials were weighed and added to 20 mL (concentration 20-45 mg / L) dye solutions with pH values ​​of 3, 5, 7, 9, and 11, respectively. The solutions were stirred at room temperature at the optimal adsorption equilibrium time. After adsorption, the supernatant was collected by high-speed centrifugation in centrifuge tubes, and its absorbance was measured using a UV-Vis spectrophotometer. The concentration corresponding to the absorbance value was calculated using a standard curve. Based on the calculated methylene blue adsorption capacity at different pH values, a curve showing the relationship between adsorption capacity and pH was plotted. Figures 17-19 As can be seen from the figure, all three materials have better adsorption effects under alkaline conditions. This is because the adsorbent deprotonates in an alkaline environment, increasing the electrostatic interaction with methylene blue.

[0095] Repeatability test: Ethanol and acetic acid (v:v=20:1) were mixed as the eluent to elute the cyclodextrin-acrylic acid / Fe3O4 composite material adsorbed with methylene blue. The eluted and dried composite material was then used to re-adsorb methylene blue. After five repeatability tests, the adsorption rate of methylene blue by the cyclodextrin-acrylic acid / Fe3O4 composite material remained above 95%, indicating that the composite material has good repeatability and practicality. The experimental results are shown in [Figure number missing]. Figure 20 .

Claims

1. A method for preparing a cyclodextrin polymer composite adsorbent material, characterized in that... Includes the following steps: Step 1: β-Cyclodextrin is activated by hydroxyl groups under the action of NaH, and then maleic anhydride is slowly added to carry out the reaction. After treatment with acetone, β-Cyclodextrin-dibutenoate derivative is obtained. Step 2: Under the action of initiator and crosslinking agent, β-cyclodextrin-dibutenoate, monomers containing double bonds and functional monomers are reacted at 50~80℃ for 8~24 h. Afterwards, the mixture is washed multiple times with anhydrous ethanol and water and dried under vacuum to obtain cyclodextrin polymer composite adsorbent material. The functional monomer is Fe3O4-dibutenoate; the double-bonded monomer is one of acrylic acid, acrylamide, and styrene; the specific preparation process is as follows: (1) Fe3O4 was dispersed in N,N-dimethylformamide, and then activated with NaH for 24 h. Maleic anhydride was then slowly added and reacted at 25~130℃ for 12~48 h. Fe3O4-dibutenoate was obtained after treatment with acetone. (2) β-Cyclodextrin was dissolved in N,N-dimethylformamide, and then the hydroxyl groups were activated by NaH for 24 h. Maleic anhydride was then slowly added and reacted at 25~130℃ for 12~48 h. After treatment with acetone, β-Cyclodextrin-dibutenoate derivative was obtained. (3) Under the action of initiator and crosslinking agent, β-cyclodextrin-dibutenoate, monomers containing double bonds and Fe3O4-dibutenoate are reacted at 50~80℃ for 8~24 h, then washed repeatedly with anhydrous ethanol and water, and dried under vacuum to obtain Fe3O4 / cyclodextrin polymer composite adsorbent material.

2. The method for preparing the cyclodextrin polymer composite adsorbent material according to claim 1, characterized in that, When β-cyclodextrin-dibutenoate reacts with acrylic acid, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 50~80℃, and the reaction time is 8~24h; the molar ratio of β-cyclodextrin-dibutenoate to acrylic acid is 1:10~1:30, and the amounts of sodium bisulfite and potassium persulfate used as initiators are 0.2%~2% of the molar amount of acrylic acid, respectively. When β-cyclodextrin-dibutenoate reacts with acrylamide, the initiators used are sodium bisulfite and potassium persulfate, the solvent is deionized water, the reaction temperature is 50~80℃, and the reaction time is 8~24h; the molar ratio of β-cyclodextrin-dibutenoate to acrylamide is 1:10~1:30, and the amounts of sodium bisulfite and potassium persulfate used are 0.2%~2% of the molar amount of acrylamide, respectively. When β-cyclodextrin-dibutenoate reacts with styrene, the initiator used is benzoyl peroxide, the solvent used is benzene, the reaction temperature is 80℃, and the reaction time is 8~24h; the mass ratio of β-cyclodextrin-dibutenoate to styrene is 1:1~1:5, and the amount of benzoyl peroxide used as the initiator is 0.1%~3% of the molar amount of styrene.

3. A cyclodextrin polymer composite adsorbent material prepared by the preparation method according to any one of claims 1 to 2.

4. The application of the cyclodextrin polymer composite adsorbent material according to claim 3 in the adsorption of methylene blue, an organic dye molecule, is characterized in that: Weigh 10 mg of cyclodextrin polymer composite adsorbent material and add it to 20 mL of a 10–400 mg / L methylene blue solution. Adsorption is carried out by magnetic stirring at 800 rpm for 15–250 min. The pH of the adsorbed dye solution is 3–11, and the adsorption temperature is 10–40 °C. After adsorption, the supernatant is collected by centrifugation, and the absorbance A at its maximum absorption wavelength is measured by UV spectrophotometer. The dye concentration is calculated based on the standard curves corresponding to each dye, and then the amount of methylene blue adsorbed at different times is calculated.

5. The application according to claim 4, characterized in that: The adsorption equilibrium times for methylene blue in the cyclodextrin-acrylic acid / Fe3O4, cyclodextrin-acrylamide / Fe3O4, and cyclodextrin-styrene / Fe3O4 composites were 120 min, 90 min, and 120 min, respectively, and the equilibrium adsorption capacities were 39.50 mg / g, 24.36 mg / g, and 20.86 mg / g, respectively.

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