Organic silicon-MOF (Metal Organic Framework) adsorption material as well as preparation method and application thereof
By introducing silicone molecules into MOF, increasing pore size and simplifying the synthesis process, the problem of low treatment efficiency of methyl orange dye in printing and dyeing wastewater in the prior art is solved, and the effect of efficient adsorption and simplifying the process is achieved.
Patent Information
- Application Number
- CN202510109631.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-04-15
AI Technical Summary
The prior art is difficult to efficiently treat methyl orange dyes in printing and dyeing wastewater, and traditional methods have problems such as high energy consumption, low efficiency or by-products.
Using silicone-MOF adsorption material, the pore size of MOF is increased by functional modification of 2-methylimidazole, the adsorption rate of methyl orange is increased, and the synthesis process of MOF is simplified.
It realizes efficient adsorption of methyl orange dye, improves adsorption rate and efficiency, simplifies the synthesis process, and has great application prospects.
Smart Images
Figure CN119819274A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of printing and dyeing wastewater treatment, and specifically relates to an organosilicon-MOF adsorption material and a preparation method and application thereof. Background Art
[0002] With the increasing awareness of global environmental protection, industrial wastewater treatment, especially the treatment of printing and dyeing wastewater, has become a difficult problem that needs to be solved urgently. Printing and dyeing wastewater contains a large amount of difficult-to-biodegrade organic matter, such as dyes and their intermediates, dyeing auxiliaries, etc. These substances not only pollute water sources, but also pose a serious threat to the ecological environment and human health. Among them, methyl orange, as a common organic dye, has a high solubility in water. However, it is difficult to degrade in water and has obvious chromaticity and biological toxicity. It is one of the typical pollutants in dye wastewater. Traditional printing and dyeing wastewater treatment methods, such as biodegradation, electrochemical destruction, and photocatalytic degradation, all have certain limitations, such as high energy consumption, low efficiency, or the generation of by-products. The adsorption method has gradually become a more ideal treatment technology due to its advantages such as simple operation, low cost, and no secondary pollution.
[0003] In recent years, metal organic framework materials (MOF), as a new type of porous material, have gradually become a hot research direction in dye wastewater treatment due to their adjustable structure, high specific surface area and excellent adsorption performance. In addition, through functional design, the dye adsorption capacity of MOF has been significantly improved, opening up a new technical path for dye wastewater treatment. Therefore, the development of a new functional MOF for dye wastewater treatment will have broad application prospects and potential. Summary of the invention
[0004] The present invention provides an organosilicon-MOF adsorption material, a preparation method and an application thereof, aiming to solve the problem of the difficulty in treating the existing methyl orange dye wastewater. The material can increase the pore size of MOF, thereby improving the adsorption rate of methyl orange; and this pre-functionalization modification method does not require additional complex post-processing steps, simplifying the synthesis process of MOF.
[0005] The technical solution of the present invention is: In a first aspect, a method for preparing an organosilicon-MOF adsorption material is disclosed, comprising the following steps: 1) Preparation of organosilicon-modified ligand: 2-methylimidazole is dissolved in organic solvent A, epoxy silane coupling agent is added dropwise at 70-100°C, the mixture is stirred for reaction for 5-7 hours, and organic solvent A is removed under reduced pressure to obtain organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: dissolving an organosilicon-modified ligand in an organic solvent B to obtain an organosilicon-modified ligand solution; dissolving cobalt nitrate hexahydrate in an organic solvent B to obtain a cobalt nitrate hexahydrate solution; adding the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, and allowing the reaction to proceed for 18 to 24 hours; collecting the precipitated product by centrifugation, washing it with an organic solvent B, and drying it under vacuum at 70 to 90° C. for 8 to 12 hours to obtain the organosilicon-MOF adsorbent material.
[0006] Preferably, the organosilicon-modified ligand is prepared under a nitrogen atmosphere, and the organic solvent A is one of tetrahydrofuran, toluene, ethanol and methanol.
[0007] Preferably, the epoxy silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-(2,3-epoxypropoxy)propyltriethoxysilane.
[0008] Preferably, the molar ratio of 2-methylimidazole to the epoxy silane coupling agent in step 1) is 1:1.0-1.2.
[0009] Preferably, the stirring rate is 800-1000 r / min.
[0010] Preferably, the organic solvent B is methanol.
[0011] Preferably, in step 2), the molar ratio of the organosilicon-modified ligand to the cobalt nitrate hexahydrate is 1:4-8.
[0012] Preferably, in step 2), the mass volume ratio of the organosilicon-modified ligand to the organic solvent B is 1:10-15; the mass volume ratio of the cobalt nitrate hexahydrate to the organic solvent B is 1:40-150.
[0013] In a second aspect, an organosilicon-MOF adsorption material prepared by the preparation method is disclosed.
[0014] In a third aspect, the application of the organosilicon-MOF adsorption material in treating wastewater containing methyl orange dye is disclosed.
[0015] The organosilicon-MOF adsorption material of the present invention adopts a method of functional modification of ligands, and utilizes the nucleophilic addition reaction of epoxy silane coupling agent and 2-methylimidazole. This chemical reaction not only has high chemical selectivity, but also has relatively mild reaction conditions. It successfully embeds organosilicon molecules into the ligand structure, and then allows these organosilicon molecules to directly participate in the construction of the MOF skeleton through covalent connection. This design idea breaks through the boundaries of traditional MOF materials. Traditional MOF materials are mainly composed of metal ions and organic ligands connected by coordination bonds, and their pore structure and performance are often limited by the type of ligands and metal ions. The organosilicon-MOF adsorption material of the present invention achieves a comprehensive improvement in the performance of MOF materials by introducing organosilicon polymers. This adsorption material formed by the synergistic chemical crosslinking between organosilicon molecules and the coordination between metal ions and imidazole has excellent adsorption performance, and the specific equations involved are as follows.
[0016] , Wherein, R is methyl or ethyl.
[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses 2-methylimidazole as a raw material, and reacts with an epoxy silane coupling agent to undergo a nucleophilic addition reaction to obtain an organosilicon-modified ligand, which is then reacted with cobalt nitrate hexahydrate to obtain an organosilicon-MOF adsorbent. The present invention has a simple process, mild conditions, good safety, and great application prospects.
[0018] 2. The adsorption performance of the organosilicon-MOF adsorbent of the present invention benefits from its unique structural characteristics. On the one hand, the pore structure formed by the coordination of the imidazole part with the cobalt ion provides the necessary space and sites for the adsorption process; on the other hand, chemical cross-linking occurs between the introduced siloxane segments, and the formed three-dimensional network structure provides more adsorption sites. Dye molecules can be adsorbed to these sites through intermolecular interactions, and mesopores appear in the modified organosilicon MOF, which greatly improves the rate of capturing dye molecules. The dual synergistic mechanism of the porous structure formed by imidazole and metal ions and the chemical cross-linking network formed by siloxane greatly improves the material's adsorption capacity and efficiency for dyes.
[0019] 3. The present invention utilizes the method of pre-functionalization modification to directly and preferentially introduce the organosiloxane segment on 2-methylimidazole without the need for additional complicated post-processing steps, thus simplifying the MOF synthesis process. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is a scanning electron microscope image of the organosilicon-MOF material prepared in Example 1.
[0021] Figure 2 It is the UV spectrum and titration curve of the supernatant titrated after the organosilicon-MOF prepared in Example 1 treated methyl orange wastewater.
[0022] Figure 3 It is the UV spectrum and titration curve of the supernatant titrated after the organosilicon-MOF prepared in Example 1 treated methyl orange wastewater. DETAILED DESCRIPTION
[0023] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0024] Example 1 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 5 g (0.06 mol) of 2-methylimidazole into a reaction flask, add 50 mL of tetrahydrofuran, and heat to 70 °C at a stirring rate of 800 r / min under nitrogen protection. After the temperature stabilizes, add 14.4 g (0.06 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane dropwise into the reaction flask. Stop the reaction after 6 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 5 g of the organosilicon-modified ligand prepared in step 1), dissolve it in 50 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 1.14 g of cobalt nitrate hexahydrate, dissolve it in 50 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 minutes, and let stand for 24 hours. Collect the precipitated product by centrifugation, wash it 3 times with methanol, and dry it at 70°C under vacuum for 8 hours to obtain the organosilicon-MOF adsorbent material. The scanning electron microscope image of the organosilicon-MOF adsorbent material is shown below. Figure 1 As shown, it presents regular granular shape, proving that the organosilicon-MOF was successfully synthesized.
[0025] The prepared organosilicon-MOF adsorption material was subjected to UV spectrum change and kinetic titration. The specific method was as follows: the adsorption sample was added to a 20 mg / L methyl orange solution, samples were taken at different time intervals, and UV tests were performed after centrifugation. The results were as follows: Figure 2 As shown in the figure, the absorbance of methyl orange at 465nm basically does not change after 5 minutes, and the adsorption equilibrium has been reached.
[0026] Example 2 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 5 g (0.06 mol) of 2-methylimidazole into a reaction flask, add 50 mL of ethanol, and heat to 80 °C at a stirring rate of 900 r / min under nitrogen protection. After the temperature stabilizes, add 15.8 g (0.07 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane dropwise into the reaction flask. Stop the reaction after 7 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 5 g of the organosilicon-modified ligand prepared in step 1) and dissolve it in 60 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 0.76 g of cobalt nitrate hexahydrate and dissolve it in 60 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 min, and let stand for 18 h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 80°C under vacuum for 10 h to obtain the organosilicon-MOF adsorbent material.
[0027] Example 3 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 4.1 g (0.05 mol) of 2-methylimidazole into a reaction flask, add 50 mL of toluene, and heat to 100 °C at a stirring rate of 1000 r / min under nitrogen protection. After the temperature stabilizes, add 12.1 g (0.05 mol) of γ-(2,3-epoxypropoxy)propyltrimethoxysilane dropwise into the reaction flask. Stop the reaction after 5 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 4 g of the organosilicon-modified ligand prepared in step 1) and dissolve it in 60 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 0.46 g of cobalt nitrate hexahydrate and dissolve it in 60 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 min, and let stand for 20 h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 90°C under vacuum for 12 h to obtain the organosilicon-MOF adsorbent material.
[0028] Example 4 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 5 g (0.06 mol) of 2-methylimidazole into a reaction flask, add 50 mL of tetrahydrofuran, and heat to 70 °C at a stirring rate of 800 r / min under nitrogen protection. After the temperature stabilizes, add 16.7 g (0.06 mol) of γ-(2,3-epoxypropoxy)propyltriethoxysilane dropwise into the reaction flask. Stop the reaction after 6 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 3 g of the organosilicon-modified ligand prepared in step 1) and dissolve it in 45 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 0.61 g of cobalt nitrate hexahydrate and dissolve it in 45 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 min, and let stand for 24 h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 70°C under vacuum for 8 h to obtain the organosilicon-MOF adsorbent material.
[0029] Example 5 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 5 g (0.06 mol) of 2-methylimidazole into a reaction flask, add 50 mL of methanol, and heat to 70 °C at a stirring rate of 900 r / min under nitrogen protection. After the temperature stabilizes, add 16.7 g (0.06 mol) of γ-(2,3-epoxypropoxy)propyltriethoxysilane dropwise into the reaction flask. Stop the reaction after 6 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 3 g of the organosilicon-modified ligand prepared in step 1) and dissolve it in 30 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 0.4 g of cobalt nitrate hexahydrate and dissolve it in 30 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 min, and let stand for 24 h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 70°C under vacuum for 10 h to obtain the organosilicon-MOF adsorbent material.
[0030] Example 6 The method for preparing the organosilicon-MOF adsorption material comprises the following steps: 1) Preparation of organosilicon-modified ligand: Weigh 7 g (0.09 mol) of 2-methylimidazole into a reaction flask, add 50 mL of ethanol, and heat to 80 °C at a stirring rate of 1000 r / min under nitrogen protection. After the temperature stabilizes, add 24.9 g (0.11 mol) of γ-(2,3-epoxypropoxy)propyltriethoxysilane dropwise into the reaction flask. Stop the reaction after 7 h, remove trace amounts of solvent under reduced pressure, and obtain the organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorbent material: Weigh 5 g of the organosilicon-modified ligand prepared in step 1) and dissolve it in 75 mL of methanol to obtain an organosilicon-modified ligand solution; weigh 0.5 g of cobalt nitrate hexahydrate and dissolve it in 75 mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30 min, and let stand for 24 h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 80°C under vacuum for 12 h to obtain the organosilicon-MOF adsorbent material.
[0031] Comparative Example 1 The method for preparing an unmodified MOF adsorption material comprises the following steps: Weigh 5g of 2-methylimidazole and dissolve it in 50mL of methanol to obtain a 2-methylimidazole solution; weigh 4.4g of cobalt nitrate hexahydrate and dissolve it in 50mL of methanol to obtain a cobalt nitrate hexahydrate solution; add the 2-methylimidazole solution to the cobalt nitrate hexahydrate solution, stir at room temperature for 30min, and let stand for 24h. Collect the precipitated product by centrifugation, wash it with methanol 3 times, and dry it at 70℃ under vacuum for 8h to obtain the unmodified MOF material ZIF-67.
[0032] The MOF adsorption material prepared in this comparative example was subjected to ultraviolet spectrum change and kinetic titration according to the method of Example 1. The titration curve is as follows: Figure 3 As shown in the figure, the absorbance of methyl orange at 465nm basically does not change after 30 minutes, and the adsorption equilibrium has been reached.
[0033] Comparative Example 2 The preparation method of the post-modified MOF adsorption material comprises the following steps: ZIF-67 was prepared according to the experimental steps in Comparative Example 1; the mixture of dried ZIF-67 and methanol was ultrasonically treated for 0.5 h. Then γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added thereto, mixed at room temperature for 1 day, and dried at 70° C. under vacuum for 8 h to obtain modified MOF nanoparticles.
[0034] Comparative Example 3 The difference from Example 1 is that in step 1) of this comparative example, the amount of γ-(2,3-epoxypropoxy)propyltrimethoxysilane added is 21.6 g, and the rest of the preparation method and steps are the same as those of Example 1.
[0035] Comparative Example 4 The difference from Example 1 is that the amount of cobalt nitrate hexahydrate added in step 2) of this comparative example is 1.52 g, and the rest of the preparation method and steps are the same as those of Example 1.
[0036] The pore size distribution of the adsorption materials prepared in the examples and comparative examples was measured. The specific test method was: nitrogen adsorption-desorption test was performed using a chemical adsorption instrument, and the pore size distribution of the sample was obtained by analyzing the adsorption-desorption curve. The test results are shown in Table 1.
[0037] Table 1 Porosity of adsorbent materials prepared in Examples and Comparative Examples
[0038] The adsorption equilibrium performance test was performed on the adsorption materials prepared in the embodiment and the comparative example. The specific test method was as follows: 5 mg of the adsorption materials prepared in the embodiment and the comparative example were weighed respectively, and added to a 20 mg / L methyl orange aqueous solution. The time to reach adsorption equilibrium is shown in Table 2.
[0039] Table 2 Adsorption equilibrium time of the adsorbent materials prepared in the examples and comparative examples
[0040] It can be seen from Table 2 that after the methyl orange wastewater solution is treated with the MOF prepared in Comparative Example 1, the adsorption-equilibrium time is much longer than the organosilicon-MOF adsorption-equilibrium time of Examples 1-6. This is because the adsorption of methyl orange in Comparative Example 1 can only rely on the pore structure of MOF, and in Comparative Example 2, when the silane coupling agent is coated on the MOF, it will cover the surface of the MOF to form a thin film. This coating layer will close the pores of the MOF to a certain extent, especially the smaller pores, resulting in a smaller effective pore size, reducing its effective pore volume and specific surface area, and thus reducing its adsorption capacity. In Comparative Example 3, the silane coupling agent is greatly excessive, and the excessive cross-linking affects the coordination ability of the modified ligand, while the ligand in Comparative Example 4 is excessive, resulting in some ligands not participating in the coordination, making the MOF grains smaller and producing more defects. In Examples 1-6, the pre-modification method is used to functionalize the ligand with silicone, which will not cause excessive coating of the ligand. It can not only rely on the pore structure formed by MOF, but also rely on the hydrogen bonding between silicon-oxygen bonds and the cross-linked network structure to make the adsorption rate of methyl orange faster.
Claims
1. A method for preparing an organosilicon-MOF adsorption material, characterized in that: The following steps are involved: 1) Preparation of organosilicon-modified ligand: 2-methylimidazole is dissolved in organic solvent A, epoxy silane coupling agent is added dropwise at 70-100°C, the mixture is stirred for reaction for 5-7 hours, and organic solvent A is removed under reduced pressure to obtain organosilicon-modified ligand; 2) Preparation of organosilicon-MOF adsorption material: dissolving the organosilicon-modified ligand in organic solvent B to obtain an organosilicon-modified ligand solution; Dissolving cobalt nitrate hexahydrate in organic solvent B to obtain a cobalt nitrate hexahydrate solution; adding the organosilicon-modified ligand solution to the cobalt nitrate hexahydrate solution, and allowing the reaction to proceed for 18 to 24 hours; The precipitated product is collected by centrifugation, washed with an organic solvent B, and dried under vacuum at 70-90° C. for 8-12 hours to obtain the organosilicon-MOF adsorption material.
2. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: The organosilicon modified ligand is prepared under a nitrogen atmosphere, and the organic solvent A is one of tetrahydrofuran, toluene, ethanol and methanol.
3. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: The epoxy silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-(2,3-epoxypropoxy)propyltriethoxysilane.
4. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: The molar ratio of 2-methylimidazole to epoxy silane coupling agent in step 1) is 1:1.0-1.
2.
5. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: The stirring rate is 800-1000r / min.
6. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: The organic solvent B is methanol.
7. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: In step 2), the molar ratio of the organosilicon-modified ligand to cobalt nitrate hexahydrate is 1:4-8.
8. The method for preparing the organosilicon-MOF adsorption material according to claim 1, characterized in that: In step 2), the mass volume ratio of the organosilicon-modified ligand to the organic solvent B is 1:10-15; the mass volume ratio of the cobalt nitrate hexahydrate to the organic solvent B is 1:40-150.
9. The organosilicon-MOF adsorption material prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the organosilicon-MOF adsorption material according to claim 9 in treating wastewater containing methyl orange dye.