A terbium-based MOF adsorbent and its preparation method and application

Abstract

The present invention provides a terbium-based MOF adsorbent and a preparation method and application thereof, and relates to the field of wastewater treatment. The method is to mix rutin acid, terbium chloride hexahydrate, acetic acid, and deionized water, use N,N-dimethylformamide as a solvent, stir and mix, then pour the mixture into a reactor for reaction, and obtain the terbium-based MOF adsorbent through post-treatment. The terbium-based MOF prepared by the present invention has the advantages of easy availability of raw materials, mild preparation reaction conditions, safe and simple method, high stability, excellent adsorption effect on pollutants and certain photocatalytic effect, and can achieve adsorption-degradation synergistic effect. In addition, the ligand selected by the present invention is a natural compound with a di-orthocatechol structure extracted from plants, which can well react with metal ions on the one hand, and on the other hand, it is greener, healthier, and more environmentally friendly than traditional ligands.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and in particular to a terbium-based MOF adsorbent and a preparation method and application thereof. Background Art

[0002] In the treatment of printing and dyeing wastewater, adsorption has become one of the most common and effective technologies due to its advantages such as low cost, simple operation, strong practicality, environmental friendliness and renewability. The selection of adsorbents is crucial for the removal of pollutants in wastewater. Currently, commonly used adsorbents include carbon-based materials such as activated carbon, metal oxides and high molecular polymers, but these adsorbents also have many shortcomings. For example, their adsorption efficiency for specific pollution sources in water bodies is relatively low due to their own limitations. Therefore, it is of great significance to develop a new adsorbent with high adsorption efficiency, good stability, versatility and practicality. This can provide a new method for the treatment of printing and dyeing wastewater.

[0003] Metal-organic frameworks are a type of crystalline porous material with a periodic network structure formed by the interconnection of inorganic metal centers (metal ions or metal clusters) and bridging organic ligands through self-assembly. Due to its high specific surface area and porosity, as well as photocatalytic properties, it shows good potential for application in the field of wastewater treatment. At the same time, metal-organic frameworks have the important characteristic of effectively separating photogenerated electrons and holes, thereby generating a large amount of active substances to oxidize pollutants. Therefore, the simultaneous removal of pollutants can be achieved through the synergistic effect of adsorption-catalytic degradation.

[0004] Existing terbium-based MOF adsorbents, one of which is Tb-MOF-76, have the problem of insufficient adsorption capacity, and only have a single adsorption effect, which cannot effectively degrade pollutants. In practical applications, they face challenges in structural stability, especially the influence of humidity, temperature changes and chemical environment that may be encountered in industrial applications (DOI: 10.1002 / anie.202213015). For another type of Tb-BTC, existing literature mentions that phosphates may replace organic ligands in the MOFs framework, resulting in partial collapse of the original structure. This indicates that Tb-BTC may undergo structural changes after adsorbing phosphates, which may affect its long-term stability and reusability. There is also the problem of only a single adsorption effect and inability to effectively degrade pollutants (DOI: 10.1016 / j.cej.2023.142751). Summary of the invention

[0005] The purpose of the present invention is to provide a terbium-based MOF adsorbent and a preparation method and application thereof. The prepared MOF adsorbent has high adsorption efficiency and certain photocatalytic properties, can achieve adsorption-degradation synergistic effects, has low processing costs, and has broad application prospects.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention first provides a method for preparing a terbium-based MOF adsorbent, comprising:

[0008] Mix rutinic acid, terbium chloride hexahydrate, acetic acid and deionized water, use N,N-dimethylformamide (DMF) as solvent, stir and mix, then pour the mixture into a reactor for reaction, and obtain a terbium-based MOF adsorbent through post-treatment.

[0009] Preferably, the molar ratio of the terbium chloride hexahydrate to the terbium chloride hexahydrate is 2:1.

[0010] Preferably, the volume ratio of the acetic acid, deionized water and N,N-dimethylformamide is 3:2:4.

[0011] Preferably, the mixing time is 25-35 min.

[0012] Preferably, the reaction temperature is 100-130° C., and the reaction time is 1.5-2.5 hours.

[0013] Preferably, the post-treatment is: after naturally cooling to room temperature, centrifuging the reaction product, washing with DMF, ethanol and deionized water in sequence, and drying in a thermostat to obtain a terbium-based MOF adsorbent.

[0014] The present invention also provides a terbium-based MOF adsorbent obtained by the above preparation method.

[0015] The present invention also provides the use of the terbium-based MOF adsorbent as a photocatalyst in the field of wastewater treatment.

[0016] Preferably, the application is specifically as follows: adding the terbium-based MOF adsorbent to printing and dyeing wastewater containing methylene blue dye for oscillating adsorption, and irradiating the printing and dyeing wastewater after reaching adsorption equilibrium under a xenon lamp light source to catalytically degrade the methylene blue dye.

[0017] Preferably, the irradiation time is 2 hours and the xenon lamp power is 500W.

[0018] Beneficial effects of the present invention

[0019] The present invention provides a terbium-based MOF adsorbent and a preparation method and application thereof. The method comprises mixing rutin acid, terbium chloride hexahydrate, acetic acid and deionized water, using N,N-dimethylformamide as a solvent, stirring and mixing, and then pouring the mixture into a reactor for reaction, and obtaining the terbium-based MOF adsorbent through post-treatment. The adsorbent is added to printing and dyeing wastewater, and the adsorption is carried out by constant temperature oscillation, and the pollutants in the water body are removed, and the water body is purified. The terbium-based MOF prepared by the present invention has high stability, excellent adsorption effect on pollutants, and a certain photocatalytic effect, and can achieve a synergistic effect of adsorption-degradation. In addition, the ligand selected by the present invention is a natural compound with a di-orthocatechol structure extracted from plants, which can react well with metal ions on the one hand, and is greener, healthier and more environmentally friendly than traditional ligands on the other hand. The present invention has a short synthesis route, a simple preparation method, mild preparation conditions, and the prepared terbium-based MOF has high acid-base stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a SEM schematic diagram of the terbium-based MOF in Example 1 of the present invention;

[0021] Figure 2 is a schematic diagram of XRD of the terbium-based MOF in Example 1 of the present invention;

[0022] Figure 3 Schematic diagram of BET and pore size distribution of terbium-based MOF in Example 1 of the present invention;

[0023] Figure 4 is a TGA schematic diagram of the terbium-based MOF in Example 1 of the present invention;

[0024] Figure 5 This is a diagram showing the adsorption effect of methylene blue dye on the terbium-based MOF in Example 2 of the present invention;

[0025] Figure 6 This is a time-effect diagram of the photocatalysis of methylene blue dye by the terbium-based MOF in Example 3 of the present invention after reaching adsorption equilibrium. DETAILED DESCRIPTION

[0026] The present invention first provides a method for preparing a terbium-based MOF adsorbent, comprising:

[0027] Mix hyaluronic acid, terbium chloride hexahydrate, acetic acid and deionized water, use N,N-dimethylformamide (DMF) as solvent, stir and mix, specifically preferably: dissolve hyaluronic acid in N,N-dimethylformamide (DMF), dissolve terbium chloride hexahydrate in deionized water, then mix the two and add acetic acid, stir and mix, the mixing time is preferably 25-35min, more preferably 30min, then pour the mixture into a reactor to react, coordinate self-assembly, the reaction temperature is preferably 100-130℃, more preferably 120℃, the reaction time is preferably 1.5-2.5 hours, more preferably 2h, and post-treatment to obtain a terbium-based MOF adsorbent. The post-treatment is preferably that after cooling naturally to room temperature, the reaction product is centrifuged, the speed of the centrifugation is preferably 7500rad / min, washed with DMF, ethanol and deionized water in turn, and dried in a constant temperature box to obtain a terbium-based MOF adsorbent. The drying temperature is preferably 80℃, and the drying time is preferably 12h. The molar ratio of the sorbic acid to terbium chloride hexahydrate is preferably 2:1, the volume ratio of the acetic acid, deionized water and N,N-dimethylformamide is preferably 3:2:4, and the concentration of the acetic acid is preferably 99.5%.

[0028] The present invention also provides a terbium-based MOF adsorbent obtained by the above preparation method.

[0029] The present invention also provides the use of the terbium-based MOF adsorbent as a photocatalyst in the field of wastewater treatment.

[0030] According to the present invention, the application is preferably: adding terbium-based MOF to printing and dyeing wastewater containing methylene blue dye for oscillation adsorption, placing the printing and dyeing wastewater after reaching adsorption equilibrium under a xenon lamp light source for irradiation, the irradiation time is preferably two hours, the xenon lamp power is 500W, and the methylene blue dye is catalytically degraded. The concentration of methylene blue in the printing and dyeing wastewater is preferably 0.5mmol / L, the volume of the printing and dyeing wastewater is preferably 10mL, and the mass of the adsorbent is preferably 10mg.

[0031] The present invention is described in detail below in conjunction with specific examples, but the present invention is not limited to the following examples. Without departing from the content and scope of the present invention, changes and implementations should be included in the scope of the present invention.

[0032] Example 1: Preparation of terbium-based MOF adsorbent

[0033] 0.3 g of hyaluronic acid was dissolved in 10 mL of N,N-dimethylformamide (DMF), and 0.1905 g of terbium chloride hexahydrate was dissolved in 5 mL of deionized water. Then the two were mixed and 7.5 mL of acetic acid was added. The mixture was stirred for 30 minutes and poured into a reactor. The mixture was placed in a 120°C thermostat for two hours to react for coordination self-assembly. After naturally cooling to room temperature, the reaction product was centrifuged at a speed of 7500 rad / min, washed with DMF, ethanol, and deionized water in turn, and dried at 80°C in a thermostat for 12 hours to obtain a terbium-based MOF adsorbent.

[0034] Figure 1 is a SEM schematic diagram of the terbium-based MOF in Example 1 of the present invention; Figure 1 It can be seen that the terbium-based MOF adsorbent synthesized in the present invention is evenly distributed.

[0035] Figure 2 is a schematic diagram of XRD of terbium-based MOF in Example 1 of the present invention; Figure 2 It can be seen that the terbium-based MOF adsorbent synthesized by the present invention has a high degree of crystallinity and no disorderly peaks, indicating that the synthesized crystals are relatively pure.

[0036] Figure 3 is a schematic diagram of BET and pore size distribution of terbium-based MOF in Example 1 of the present invention; Figure 3 It can be seen that the MOF synthesized in the present invention has a large specific surface area, and the pore size is microporous and mesoporous structure.

[0037] Figure 4 is a schematic diagram of TGA of terbium-based MOF in Example 1 of the present invention; Figure 4 It can be seen that the MOF material synthesized by the present invention has good thermal stability and can maintain good stability below 400°C.

[0038] Example 2: Adsorption of methylene blue by terbium-based MOF adsorbent

[0039] The terbium-based MOF sample of Example 1 was fully dried, and then 10 mg of terbium-based MOF and 10 mL of 0.5 mmol methylene blue dye were added to a sealable 25 mL glass bottle, and adsorption was carried out in an oscillating water bath at room temperature. The remaining dye concentration was measured at regular intervals until equilibrium was reached.

[0040] Figure 5 This is a diagram showing the adsorption effect of methylene blue dye on terbium-based MOF in Example 2 of the present invention. Figure 5 It can be seen that the MOF synthesized in Example 1 of the present invention has good adsorption performance for methylene blue.

[0041] Example 3: Catalytic degradation of methylene blue dye by terbium-based MOF

[0042] After the adsorption of methylene blue dye by the terbium-based MOF in Example 2 reached equilibrium, it was placed under a xenon lamp light source with a power of 500 W for photocatalytic degradation.

[0043] Figure 6 This is a time-effect diagram of the photocatalytic effect of terbium-based MOF on methylene blue dye after reaching adsorption equilibrium in Example 3 of the present invention. Figure 6 It can be seen that the MOF material synthesized in Example 1 of the present invention has a certain photocatalytic performance for methylene blue. The pollutant concentration decreases slowly at the beginning because the pollutants adsorbed in the adsorbent are first degraded. After the pollutants adsorbed on the adsorbent are completely degraded, the pollutants in the sewage will begin to be degraded. Therefore, the pollutant concentration decrease curve will show a slow-fast-slow trend.

Claims

1. A method for preparing a terbium-based MOF adsorbent, characterized in that: include: Mix rutinic acid, terbium chloride hexahydrate, acetic acid and deionized water, use N,N-dimethylformamide as solvent, stir and mix, then pour the mixture into a reactor for reaction, and obtain a terbium-based MOF adsorbent through post-treatment.

2. The method for preparing a terbium-based MOF adsorbent according to claim 1, characterized in that: The molar ratio of the terbium chloride hexahydrate to the terbium chloride hexahydrate is 2:

1.

3. The method for preparing a terbium-based MOF adsorbent according to claim 1, characterized in that: The volume ratio of the acetic acid, deionized water and N,N-dimethylformamide is 3:2:

4.

4. The method for preparing a terbium-based MOF adsorbent according to claim 1, characterized in that: The mixing time is 25-35 minutes.

5. The method for preparing a terbium-based MOF adsorbent according to claim 1, characterized in that: The reaction temperature is 100-130° C., and the reaction time is 1.5-2.5 hours.

6. The method for preparing a terbium-based MOF adsorbent according to claim 1, characterized in that: The post-treatment is as follows: after naturally cooling to room temperature, centrifuging the reaction product, washing with DMF, ethanol and deionized water in sequence, and drying in a constant temperature box to obtain a terbium-based MOF adsorbent.

7. The terbium-based MOF adsorbent obtained by the preparation method according to claim 1.

8. Use of the terbium-based MOF adsorbent according to claim 7 as a photocatalyst in the field of wastewater treatment.

9. The use according to claim 8, characterized in that: The application is specifically as follows: adding the terbium-based MOF adsorbent to printing and dyeing wastewater containing methylene blue dye for oscillation adsorption, placing the printing and dyeing wastewater after reaching adsorption equilibrium under a xenon lamp light source for catalytic degradation of the methylene blue dye.

10. The use according to claim 9, characterized in that: The irradiation time is 2 hours, and the xenon lamp power is 500W.

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