Preparation method and application of magnetic aminated lignosulfonate metal organic framework material

Abstract

The invention discloses a preparation method of a magnetic aminated lignosulfonate metal organic framework material, which comprises the following steps: S1, respectively dissolving Co (NO3) 2.6 H2O and C4H6N2 in a methanol solution to obtain a pink solution A and a colorless solution B; s2, adding the magnetic aminated sodium lignin sulfonate into the solution A, and mixing and stirring; s3, pouring the solution B into the solution A, fully magnetically stirring, standing, and centrifugally separating to obtain a compound; and S4, washing the compound obtained in the step S3 for several times, carrying out vacuum drying at 50-70 DEG C, and grinding to obtain the magnetic aminated sodium lignin sulfonate-based metal organic framework material. The technical bottlenecks of low adsorption efficiency and high cost on methyl blue dye wastewater and difficulty in regeneration and degradation of an adsorbent in the prior art are overcome; the problem of weak mechanical strength is overcome, and the potential of efficiently purifying, adsorbing and treating methyl blue molecules in dye wastewater is found.

Description

Technical Field

[0001] The present invention relates to the field of adsorption materials, and particularly to a preparation method and application of a magnetic aminated lignosulfonate metal-organic framework material. Background Art

[0002] In recent years, with the rapid development of industrial economy, people's demands for environmental protection and high-quality water purification have become increasingly urgent. To meet the growing social demands for environmental protection and ecology, it is necessary to design degradable and regenerable adsorption materials with high quality, high stability, large adsorption capacity and good regeneration performance. At present, different adsorbents based on lignin-modified materials have been developed, including amination modification, metal ion exchange modification and biomass carbon. The main electrostatic interaction is known for its high saturation. This original adsorbent has a high adsorption capacity and a large specific surface area, and is widely used in fields such as food, water and air adsorption.

[0003] ZIF-67 (metal-organic framework) has the advantages of a hydrophobic surface, high chemical and thermal stability, a large surface area and water stability. ZIF-67 can be an excellent adsorbent for removing dyes from aqueous solutions. However, it has obvious disadvantages, such as poor recyclability and difficult separation. A feasible method is to form magnetic composites to facilitate the perfect separation of the adsorbent by an external magnet instead of by traditional separation methods (filtration, centrifugation, etc.). Common magnetic nanoparticles include Fe 3 O 4 、Fe 2 O 3 、CoFe 2 O 4 and MnFe 2 O 4 ,which can be used to prepare magnetic composites. Among them, Fe 3 O 4 is a friendly choice for magnetism due to its low price and good stability. It can be prepared by coprecipitation method, hydrothermal method, pyrolysis method, sol-gel method, microemulsion method, sonochemical method, electrodeposition method and polyol method. Combining magnetic nanoparticles with MOFs to prepare highly porous magnetic metal-organic framework composites (MMOFs), according to the way of combining magnetic nanoparticles with MOFs, it can be divided into core-shell structure, embedded structure and irregular structure.

[0004] In the present invention, through the design of imidazole monomer molecules, a magnetic aminated lignosulfonate metal imidazole organic framework material is synthesized. Among them, the imidazole ring structure has good adsorption function, and the metal-organic framework material promotes the adsorption reaction kinetics between methylene blue and aminated lignosulfonate. The addition of magnetism improves the separation efficiency. Therefore, the magnetic metal-coordinated imidazole organic framework material exhibits excellent adsorption performance and cyclic regeneration performance in methylene blue dye wastewater.

[0005] The present invention utilizes magnetic iron oxide and metal single atom imidazole organic framework material to realize coordination, so that the molecular layer spacing of the imidazole organic aminated lignin sulfonate polymer material is increased, and the adsorption regeneration cycle performance is improved, so that methyl blue can be better physically and chemically adsorbed, and the adsorption reaction kinetics between methyl blue and aminated lignin sulfonate can be significantly improved, thereby significantly improving the physical and chemical adsorption performance of the aminated lignin sulfonate. Summary of the invention

[0006] The object of the present invention is to provide a preparation method of a magnetic aminated lignin sulfonate metal organic framework material and its application, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing a magnetic aminated lignin sulfonate metal organic framework material, comprising the following steps: S1, Co(NO 3 ) 2 6H 2 O and C 4 H 6 N 2 Dissolved in methanol solution respectively, pink solution A and colorless solution B were obtained; S2, adding magnetic aminated sodium lignin sulfonate to solution A and mixing; S3, pouring solution B into solution A, stirring the solution magnetically and allowing it to stand, and separating the solution by centrifugation to obtain the compound; S4, washing the compound obtained in step S3 for several times, drying it in a vacuum at 50-70° C., and grinding it to obtain a magnetic aminated sodium lignin sulfonate-based metal organic framework material.

[0008] Preferably, the preparation of magnetic aminated sodium lignin sulfonate in step S2 comprises the following steps: A1. Amination of sodium lignin sulfonate and FeCl 3 6H 2 O is dispersed in ethylene glycol, and then trisodium citrate and sodium acetate are added, and ultrasonic dispersion is performed to obtain a yellow solution C; A2, transferring solution C to a reactor and heating for reaction, cooling naturally to obtain a separated product and washing it several times; A3, drying in a vacuum oven, and grinding to obtain magnetic aminated sodium lignin sulfonate.

[0009] Preferably, the preparation of aminated sodium lignin sulfonate in step A1 comprises the following steps: B1. Dissolve sodium lignosulfonate in a three-necked flask containing sodium hydroxide solution, and form a uniform solution D by ultrasonic treatment. Heat solution D to 40 - 60 °C, and then add diethylenetriamine to solution D and mix well. B2. Heat the three-necked flask to 70 - 90 °C, then dropwise add aqueous formaldehyde solution, and adjust the pH of solution D to acidic with hydrochloric acid until no brown precipitate precipitates. B3. Wash solution D several times with isopropyl alcohol and petroleum ether, and then wash with deionized water until solution D is neutral. B4. Place solution D in a vacuum dryer at 50 °C, and obtain aminated sodium lignosulfonate after grinding.

[0010] Preferably, in step S1, the molar ratio of Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 is 1:7 - 8.

[0011] Preferably, in step S2, the rotation speed of the mixing and stirring is 500 r / min, and the stirring duration is 3 h.

[0012] Preferably, in step S3, the rotation speed of the magnetic stirring is 500 r / min, the stirring duration at room temperature is 24 h, and the standing duration is 10 min.

[0013] Preferably, in step A2, the heating temperature of the reaction kettle is 200 °C, and the reaction duration is 8 h.

[0014] Preferably, in step A3, the drying temperature of the drying oven is 60 °C, and the reaction duration is 3 h.

[0015] Preferably, in step B1, the mass ratio of sodium lignosulfonate to diethylenetriamine is 4:1.

[0016] The present invention also relates to the application of the magnetic aminated lignosulfonate metal-organic framework material in the adsorption treatment of methylene blue molecules in dye wastewater.

[0017] Advantages of the present invention: By providing a preparation method and application of a magnetic metal-organic framework material aminated lignosulfonate adsorbent, the technical bottlenecks of the prior art, such as low adsorption efficiency and high cost for methylene blue / dye wastewater adsorption, and the difficulty in regeneration and degradation of the adsorbent, are overcome; the problem of weak mechanical strength is overcome, and the potential of efficiently purifying and adsorbing methylene blue molecules in dye wastewater is discovered. Brief Description of the Drawings

[0018] Figure 1 It is a flow chart of the preparation method of the embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1 See also Figure 1 The present invention provides a method for preparing a magnetic aminated lignin sulfonate metal organic framework material, comprising the following steps: S1, 0.733gCo(NO 3 ) 2 6H 2 O and 1.623 g 2-methylimidazole C 4 H 6 N 2 Dissolve in 50 ml of methanol solution to obtain pink solution A and colorless solution B; S2, 0.0365g of magnetic aminated sodium lignin sulfonate (AELS@Fe 3 O 4 ) was added into solution A and stirred at a speed of 500 r / min for 3 h; S3, then pouring solution B into solution A, fully stirring with magnetic stirring and standing for 10 min, controlling the stirring speed to 500 r / min, stirring at room temperature for 24 h, and centrifuging to obtain the compound; S4, washing the compound obtained in step S3 with methanol three times, removing the residual Co(NO 3 ) 2 6H 2 O and 2-methylimidazole C 4 H 6 N 2 The material was removed, dried in vacuum at 60°C, and ground to obtain a magnetic aminated sodium lignin sulfonate-based metal-organic framework material.

[0021] Specifically, the preparation of magnetic aminated sodium lignin sulfonate in step S2 comprises the following steps: A1. Mix 1g of aminated sodium lignin sulfonate (AELS) and 2.83g of FeCl 3 6H 2 O was dispersed in 70 ml of ethylene glycol, and then 0.53 g of trisodium citrate and 4.20 g of sodium acetate were added, and ultrasonic dispersion was performed to obtain a yellow solution C; A2. Transfer solution C to a reaction kettle, heat it to 200 °C and react for 8 h. After natural cooling, use a magnet to separate to obtain a separated product, wash the separated product three times with water and ethanol, and remove the remaining AELS and FeCl3 that did not form the separated product; A3. Dry it in a vacuum oven at 60 °C for 3 h, and grind to obtain magnetic aminated sodium lignosulfonate.

[0022] Preferably, the preparation of aminated sodium lignosulfonate in step A1 includes the following steps: B1. Dissolve 10 g of sodium lignosulfonate (ELS) in a three-necked flask containing 20 ml of 0.5 mol / L sodium hydroxide solution, form a uniform solution D by ultrasonic treatment, heat solution D to 55 °C, and then add 2.5 g of diethylenetriamine to solution D and mix well; B2. Raise the temperature of the three-necked flask to 85 °C, slowly dropwise add 4.5 ml of aqueous formaldehyde solution under the conditions of condensation reflux and magnetic stirring, react for 4 h, and adjust solution D to acidic with 1 mol / L hydrochloric acid until no brown precipitate precipitates; B3. Wash solution D three times with isopropanol and petroleum ether, and then wash with deionized water until solution D is neutral; B4. Place solution D in a vacuum drying at 50 °C, and grind to obtain aminated sodium lignosulfonate.

[0023] Specifically, in step S1, the molar ratio of Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 is 1:7, and it is formulated into a solution for pre-synthesizing magnetic aminated lignosulfonate metal-organic framework materials.

[0024] Specifically, the mass ratio of sodium lignosulfonate to diethylenetriamine in step B1 is 4:1.

[0025] The present invention also relates to the application of magnetic aminated lignosulfonate metal-organic framework materials in the adsorption treatment of methyl blue molecules in dye wastewater.

[0026] Specifically, mix the magnetic aminated sodium lignosulfonate AELS@Fe3O4 solution and the pre-synthesis solution of the metal-organic framework material at a mass ratio of 1:1 in a glass beaker, stir evenly to obtain a dispersion liquid, and then transfer it to a hydrothermal kettle for reaction to obtain magnetic aminated lignosulfonate metal-organic framework materials coordinated with different metal single atoms.

[0027] Example 2 In step S1, Co(NO 3 ) 2 ·6H2 O and C 4 H 6 N 2 The molar ratio is 1:7.5, and the solution of magnetic aminated lignosulfonate AELS@Fe3O4 and the pre-synthesis solution of metal-organic framework material are in a mass ratio of 1:1.5.

[0028] The preparation steps are the same as those in Example 1, only adjusting the molar ratio of the precursors and the addition amount of magnetic aminated lignosulfonate AELS@Fe3O4.

[0029] In the adsorption experiment, in 25 mL of methylene blue solution with a concentration of 300 mg / L (pH = 6), the maximum adsorption amount of methylene blue was measured to be 441 mg / g, which is less than the adsorption amount of the material in Example 1 under the same conditions (565 mg / g). Since Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 As the molar ratio of 4 H 6 N 2 increases, an excess of C

[0030] Example 3 In step S1, Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 The molar ratio is 1:8, and the solution of magnetic aminated lignosulfonate AELS@Fe3O4 and the pre-synthesis solution of metal-organic framework material are in a mass ratio of 1:2.

[0031] The preparation steps are the same as those in Example 1, only adjusting the molar ratio of the precursors and the addition amount of magnetic aminated lignosulfonate AELS@Fe3O4.

[0032] In the adsorption experiment, in 25 mL of methylene blue solution with a concentration of 300 mg / L (pH = 6), the maximum adsorption capacity of methylene blue was measured to be 374 mg / g, significantly lower than that in Examples 1 and 2. This was mainly due to the excess of 2-methylimidazole and the decrease in the addition amount of magnetic aminated lignosulfonate AELS@Fe3O4, resulting in the coverage of active sites and pore blockage. In the recycling experiment, the magnetic recovery rate of the material was 80.6%, which further decreased compared with Examples 1 and 2. The magnetic property weakened because of the too low content of magnetic aminated lignosulfonate AELS@Fe3O4.

[0033] Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 When the molar ratio of Co(NO

[0034] Example 4 In step S1, the molar ratio of Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 was 1:6, and the magnetic aminated lignosulfonate AELS@Fe3O4 solution and the pre-synthesis solution of the metal-organic framework material were in a mass ratio of 1:0.75.

[0035] In the adsorption experiment, in 25 mL of methylene blue solution with a concentration of 300 mg / L (pH = 6), the maximum adsorption capacity of methylene blue was measured to be 387 mg / g, significantly lower than that in Example 1. In the recycling experiment, the magnetic recovery rate of the material was 93.1%, close to that in Example 1. The increase in the content of AELS@Fe3O4 did not significantly affect the recovery rate.

[0036] Co(NO 3 ) 2 ·6H 2 O and C 4 H 6 N 2 When the molar ratio of Co(NO

[0037] Study on the magnetization intensity of magnetic aminated lignosulfonate metal-organic framework materials The magnetization intensity of the magnetic aminated lignosulfonate metal-organic framework material obtained by the method of the present invention was studied. The magnetism of the prepared material was evaluated by vibrating sample magnetometer (VSM) analysis. The saturation magnetization intensity (Ms) of different materials is shown in Table 1.

[0038] Table 1 Saturation magnetization intensity of different materials The results show that due to the coating of AELS and ZIF-67 on Fe 3 O 4 with a low content of Fe 3 O 4 the Ms of the prepared AELS@Fe 3 O 4 @ZIF-67 decreased compared with Fe 3 O 4 and AELS@Fe 3 O 4 but still exhibited sufficient magnetization intensity. After the adsorption was completed, the magnetic composite adsorbent was quickly separated from the dye solution by an external magnet, facilitating recycling and reuse.

[0039] Adsorption study of magnetic aminated lignosulfonate metal-organic framework materials in methylene blue solutions with different pH values The effect of the solution pH value in the range of 3 to 10 on the adsorption of methylene blue by AELS@Fe 3 O 4 @ZIF-67 was studied (Table 2). It can be seen from Table 2 that as the pH increased from 3 to 10, the adsorption amount showed a trend of first increasing and then decreasing. Under weakly acidic or near-neutral conditions, the adsorption amount of methylene blue was higher than that under strongly acidic or strong alkaline conditions. Under strongly acidic conditions, a large number of hydrogen ions might compete with AELS@Fe 3 O 4 @ZIF-67, resulting in a decrease in the adsorption amount of methylene blue. Under strong alkaline conditions, the decrease in the adsorption amount could be attributed to the increasing number of hydroxide ions on the surface of AELS@Fe 3 O 4 @ZIF-67 competing with the anionic dye, leading to a decrease in the adsorption amount. At pH = 6, the adsorption amount of methylene blue by the AELS@Fe 3 O 4 @ZIF-67 material was the largest, reaching 565 mg g -1 . Therefore, pH = 6 was selected as the optimal adsorption condition in subsequent experiments.

[0040] Table 2 Adsorption amount of magnetic aminated lignosulfonate metal-organic framework materials under different pH conditions The magnetic aminated lignosulfonate metal-organic framework material obtained by the method of the present invention was used in the adsorption treatment experiment of methylene blue molecules in dye wastewater: 0.01 g of the magnetic aminated lignosulfonate metal-organic framework material was added to 25 mL of a methylene blue solution with a concentration of 300 mg / L (pH = 6), and it was oscillated in a constant-temperature water bath for 15 minutes. Then, the supernatant was centrifuged at 8000 r / min for 5 min. Using deionized water as a reference, the absorbance of the dye in the supernatant before and after adsorption at the maximum absorption wavelength was measured with a UV spectrophotometer, and the concentration was calculated according to the standard curve. The maximum adsorption capacity of methylene blue measured in the experiment was 565 mg / g, and the removal rate was 73.2%. The relationship between the adsorption capacity and removal rate of methylene blue and the adsorption dose of the magnetic aminated lignosulfonate metal-organic framework material is shown in Table 3.

[0041] Table 3 Adsorption capacity and removal rate of methylene blue at different adsorption doses of the magnetic aminated lignosulfonate metal-organic framework material It can be seen from Table 3 that as the adsorption dose of the magnetic aminated lignosulfonate metal-organic framework material increased from 0.01 g to 0.05 g, the adsorption capacity of the magnetic aminated lignosulfonate metal imidazole organic framework material (AELS@Fe3O4@ZIF-67) for methylene blue decreased from 565 mg / g to 140 mg / g, and the removal rate increased from 73.2% to 90.9%. The opportunity for AELS@Fe3O4@ZIF-67 with a unit mass to adsorb methylene blue decreased with the increase in the number of active sites.

[0042] Application of recycling the magnetic aminated lignosulfonate metal-organic framework material: The adsorbed magnetic aminated lignosulfonate metal-organic framework material was recovered by applying an external magnetic field, then ultrasonically dispersed in 20 mL of an eluent (ethanol), and then thoroughly washed with deionized water and reused in the next adsorption process. The adsorption experiment was repeated under the conditions of 25 °C, 25 mL of a methylene blue solution with a concentration of 300 mg / L, and 0.01 g of the magnetic aminated lignosulfonate metal-organic framework material. The relationship between the number of uses of the magnetic aminated lignosulfonate metal-organic framework material and the adsorption capacity is shown in Table 4.

[0043] Table 4 Adsorption capacity of the magnetic aminated lignosulfonate metal-organic framework material at different numbers of uses The regeneration performance of the recycled magnetic aminated lignosulfonate metal-organic framework material is shown in Table 4. It can be seen from Table 4 that after five adsorption experiments, the adsorption effect is still relatively stable. The adsorption capacity at the fifth use is 433 mg / g, overcoming the problems of low adsorption efficiency, high cost, and difficulty in regeneration and degradation of adsorbents for methyl blue / dye wastewater in the prior art.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a magnetic aminated lignin sulfonate metal organic framework material, characterized in that: The following steps are involved: S1. Dissolve Co(NO3)2·6H2O and C4H6N2 in methanol solution to obtain pink solution A and colorless solution B; S2, adding magnetic aminated sodium lignin sulfonate to solution A and mixing; S3, pouring solution B into solution A, stirring the solution magnetically and allowing it to stand, and separating the solution by centrifugation to obtain the compound; S4, washing the compound obtained in step S3 for several times, drying it in a vacuum at 50-70° C., and grinding it to obtain a magnetic aminated sodium lignin sulfonate-based metal organic framework material.

2. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 1, characterized in that: The preparation of magnetic aminated sodium lignin sulfonate in step S2 comprises the following steps: A1. Disperse aminated sodium lignin sulfonate and FeCl3·6H2O in ethylene glycol, add trisodium citrate and sodium acetate, and disperse uniformly by ultrasonication to obtain a yellow solution C; A2, transferring solution C to a reactor and heating for reaction, cooling naturally to obtain a separated product and washing it several times; A3, drying in a vacuum oven, and grinding to obtain magnetic aminated sodium lignin sulfonate.

3. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 2, characterized in that: The preparation of aminated sodium lignin sulfonate in step A1 comprises the following steps: B1. Dissolve sodium lignin sulfonate in a three-necked flask filled with sodium hydroxide solution, form a uniform solution D through ultrasound, heat the solution D to 40-60°C, and then add diethylenetriamine to the solution D and mix thoroughly; B2. Heat the three-necked flask to 70-90°C, then drop the formaldehyde solution and adjust the solution D to acidity with hydrochloric acid until no brown precipitate is precipitated; B3, washing solution D several times with isopropanol and petroleum ether, and then washing with deionized water until solution D is neutral; B4. Place solution D at 50°C for vacuum drying and grind to obtain aminated sodium lignin sulfonate.

4. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 1, characterized in that: In the step S1, the molar ratio of Co(NO3)2·6H2O to C4H6N2 is 1:7-8, which is used to prepare a solution for pre-synthesizing a magnetic aminated lignin sulfonate metal organic framework material.

5. The method for preparing an aminated lignin sulfonate material according to claim 1, characterized in that: The mixing and stirring speed in step S2 is 500 r / min, and the stirring time is 3 h.

6. The method for preparing the magnetic aminated lignin sulfonate metal organic framework material according to claim 1, characterized in that: In step S3, the rotation speed of the magnetic stirring is 500 r / min, the stirring time at room temperature is 24 h, and the static time is 10 min.

7. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 1, characterized in that: In the step A2, the heating temperature of the reactor is 200° C., and the reaction time is 8 hours. In the step A3, the drying temperature of the drying box is 60° C., and the reaction time is 3 hours.

8. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 4, characterized in that: The mass ratio of the pre-synthesized solution of the magnetic aminated sodium lignin sulfonate and the metal organic framework material is 1:1-2, and is used to obtain the magnetic aminated sodium lignin sulfonate metal organic framework material coordinated by different metal single atoms.

9. The method for preparing a magnetic aminated lignin sulfonate metal organic framework material according to claim 3, characterized in that: The mass ratio of sodium lignin sulfonate to diethylenetriamine in step B1 is 4:

1.

10. Use of the magnetic aminated sodium lignin sulfonate-based metal organic framework material obtained by the preparation method of a magnetic aminated sodium lignin sulfonate metal organic framework material according to any one of claims 1 to 9 in dye wastewater.

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