Preparation method of bifunctional MCM-41 molecular sieve for adsorbing and detecting aluminum ions
By grafting Schiff base ligand with fluorescence characteristics and metal ion chelation function onto the MCM-41 molecular sieve, a dual-function MCM-41 adsorbent was prepared, which solved the problem of limited adsorption capacity and no detection function of the unmodified MCM-41 molecular sieve, and achieved efficient adsorption and high sensitivity detection, and was simple and low in synthesis.
Patent Information
- Application Number
- CN202510152096.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-12
- Publication Date
- 2025-05-13
AI Technical Summary
The existing unmodified MCM-41 molecular sieve has a slow adsorption rate and limited adsorption capacity, and does not have detection functions, which limits its application prospects. At the same time, existing dual-function adsorbents often have problems such as complex and high cost in both the high metal ion adsorption capacity and high detection sensitivity.
By reacting Schiff base with the amino group of the silane coupling agent with the active aldehyde group of the organic compound, a Schiff base ligand with fluorescence characteristics and metal ion chelation function was obtained, and silanized with the hydroxyl group on the surface of the MCM-41 molecular sieve, the Schiff base ligand was introduced to the surface of the MCM-41 molecular sieve, and a dual-function MCM-41 adsorbent with high adsorption capacity and high sensitivity detection was prepared.
The adsorption capacity of MCM-41 molecular sieve is significantly improved, and it is given the detection function of aluminum ions, achieving efficient adsorption and high sensitivity detection of aluminum ions in aqueous solution. The synthesis steps are simple and low cost, which is suitable for industrial production.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of inorganic functionalized materials, and in particular relates to a method for preparing a bifunctional MCM-41 molecular sieve for adsorbing and detecting aluminum ions. Background Art
[0003] At present, commonly used adsorbents mainly include biosorbents, polymer material adsorbents, graphene, molecular sieve adsorbents and carbon-based material adsorbents. Kito et al. used graphene modified with sodium dodecyl sulfate to achieve effective adsorption of aluminum ions, and its adsorption capacity reached 40.82 mg / g (International Journal of Environmental Science and Technology, 2020, 5, 1735-1472). In addition, MCM-41 molecular sieve has potential application value in removing metal ions because of its low cost, large specific surface area, rich oxygen-containing functional groups and reusability (Separation and Purification Technology, 2025, 353, 128421). However, the unmodified MCM-41 molecular sieve has a slow adsorption rate and limited adsorption capacity for metal ions, and does not have a detection function, which greatly limits its application prospects.
[0004] At present, the use of fluorescence detection to determine metal ions has become an important method. This method has attracted much attention due to its simplicity, economy, and sensitivity. Liu et al. used 4-aminobenzoyl hydrazide and 2-hydroxy-1-naphthaldehyde to synthesize the Schiff base ABHS fluorescent probe, and the detection limit of aluminum ions can reach 6.7×10 -6mol / L, with good aluminum ion detection function (Spectrochimica Acta Part A:Molecular and Biomolecular Spectroscopy, 2024, 2, 1386-1425). However, since fluorescent probe molecules are usually organic compounds, they are difficult to recover after use in aqueous solution and cannot be reused, which limits their practical application. To solve the above problems, organic ligands with fluorescence response function are grafted onto porous materials to obtain adsorbents with both metal ion adsorption and detection functions, which has become a research hotspot (Chinese Journal of Chemical Engineering, 2023, 60, 108-117). However, due to the different selection of Schiff base ligands and porous materials, this type of bifunctional adsorbent often cannot take into account both high metal ion adsorption capacity and high detection sensitivity at the same time. For example, the metal ion adsorption capacity is high, but the detection sensitivity is low; or the detection sensitivity is high and the metal ion adsorption capacity is low. Moreover, the synthesis process of this type of bifunctional adsorbent is relatively complicated and the cost is relatively high.
[0005] Therefore, it is imperative to develop a bifunctional adsorbent with simple process, low cost, and both efficient adsorption and high-sensitivity detection of aluminum ions. Summary of the invention
[0006] In view of the above-mentioned technical problems, the present invention provides a method for preparing a bifunctional MCM-41 molecular sieve for adsorbing and detecting aluminum ions. The method is to use the amino group of a silane coupling agent to react with the active aldehyde group of an organic compound to produce a Schiff base ligand having fluorescence characteristics and metal ion chelating function; then the Schiff base ligand is subjected to a silanization reaction with the hydroxyl group on the surface of the MCM-41 molecular sieve, and the Schiff base ligand having both luminescence characteristics and chelating function for aluminum ions is introduced to the surface of the MCM-41 molecular sieve, thereby obtaining a bifunctional MCM-41 adsorbent with high adsorption capacity and high sensitivity detection. This method can not only significantly improve the adsorption capacity of the MCM-41 molecular sieve, but also enable the MCM-41 molecular sieve to have the detection function for aluminum ions.
[0007] The purpose is achieved through the following technical solutions:
[0008] The preparation method of the bifunctional MCM-41 molecular sieve for adsorbing and detecting aluminum ions of the present invention comprises the following steps:
[0009] (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function:
[0010] Disperse 0.011-0.023 mol of a silane coupling agent and 0.011-0.023 mol of an organic compound in 50-200 ml of an organic solvent, then add 0.05-0.2 ml of 1-5 mol / l glacial acetic acid to the mixed solution, and heat and stir at 60-90° C. for 12-36 hours under the protection of an inert gas to obtain a Schiff base ligand dispersion;
[0011] (2) Preparation of bifunctional MCM-41 molecular sieve:
[0012] Disperse 1-1.5 g of MCM-41 molecular sieve in 100-300 ml of organic solvent, and perform ultrasonic dispersion for 1-3 hours to obtain a MCM-41 molecular sieve dispersion liquid. Add the Schiff base ligand obtained in step (1) dropwise into the MCM-41 molecular sieve dispersion liquid. Stir and reflux at 60-90° C. for 12-36 hours, and wash with an organic solvent until neutral. Dry in a vacuum drying oven at 50-80° C. for 12-36 hours to obtain a bifunctional MCM-41 molecular sieve.
[0013] Furthermore, in step (1), the silane coupling agent is selected from one of ureapropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.
[0014] Furthermore, the organic compound in step (1) is selected from one of 2-hydroxy-1-naphthaldehyde, 2,4-dihydroxybenzaldehyde, 8-quinolinecarboxaldehyde and salicylaldehyde.
[0015] Furthermore, the inert gas in step (1) is one of nitrogen, argon and helium.
[0016] Furthermore, the organic solvent is one of anhydrous dimethyl sulfoxide, anhydrous ethanol, anhydrous methanol and anhydrous toluene.
[0017] The beneficial effects of the present invention are:
[0018] The preparation method of the present invention is to use the amino group of the silane coupling agent and the active aldehyde group of the organic compound to undergo Schiff base reaction under homogeneous conditions to obtain a Schiff base ligand with fluorescence characteristics and metal ion chelating function; then the Schiff base ligand is subjected to a silanization reaction with the hydroxyl group on the surface of the MCM-41 molecular sieve, and the Schiff base ligand is introduced into the surface of the MCM-41 molecular sieve to obtain an aluminum ion adsorbent with high adsorption capacity and high sensitivity detection. The adsorbent synthesized by the method not only has an efficient chelating function for aluminum ions, but also can achieve high sensitivity detection of aluminum ions, significantly improves the adsorption capacity of the MCM-41 molecular sieve, and realizes the dual functions of adsorption and detection of aluminum ions in aqueous solution. By grafting the Schiff base ligand onto the MCM-41 to prepare the bifunctional molecular sieve material, the advantages of inorganic materials and organic compounds are integrated, not only the high chelating and coordination ability of organic compounds to aluminum ions is utilized, but also the advantage of the MCM-41 molecular sieve being recyclable and reusable is retained. The method has simple synthesis steps, low cost, continuous operation, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a surface SEM image of the bifunctional MCM-41 molecular sieve of the present invention;
[0020] Figure 2 is a TEM image of the bifunctional MCM-41 molecular sieve of the present invention;
[0021] Figure 3 is the XRD diagram of the bifunctional MCM-41 molecular sieve of the present invention;
[0022] Figure 4 The bifunctional MCM-41 molecular sieve in the present invention adsorbs Al 3+ The full spectrum of XPS after;
[0023] Figure 5 It is the fluorescence selectivity of the bifunctional MCM-41 molecular sieve to metal ions in the present invention. DETAILED DESCRIPTION
[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments.
[0025] Embodiment 1:
[0026] (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function:
[0027] 0.011 mol of ureapropyltrimethoxysilane and 0.011 mol of salicylaldehyde were dispersed in 50 ml of anhydrous dimethyl sulfoxide solvent, and then 0.05 ml of 3 mol / l glacial acetic acid was added to the mixture. Under argon protection, the mixture was heated and stirred at 60° C. for 12 h to obtain a Schiff base ligand dispersion.
[0028] (2) Preparation of bifunctional MCM-41 molecular sieve:
[0029] Disperse 1g of MCM-41 molecular sieve in 100ml of anhydrous dimethyl sulfoxide solvent, and disperse by ultrasonic for 1h. Add the Schiff base ligand obtained in step (1) dropwise into the MCM-41 molecular sieve dispersion. After stirring and refluxing at 60°C for 12h, wash with anhydrous dimethyl sulfoxide until neutral, and dry in a vacuum drying oven at 50°C for 12h to obtain a bifunctional MCM-41 molecular sieve.
[0030] Embodiment 2:
[0031] (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function:
[0032] 0.016 mol 3-aminopropyltrimethoxysilane and 0.018 mol 8-quinolinecarboxaldehyde were dispersed in 100 ml of anhydrous ethanol solvent, and then 0.1 ml of 1 mol / l glacial acetic acid was added to the mixed solution. Under nitrogen protection, the mixture was heated and stirred at 80° C. for 24 h to obtain a Schiff base ligand dispersion.
[0033] (2) Preparation of bifunctional MCM-41 molecular sieve:
[0034] 1.2 g of MCM-41 molecular sieve was dispersed in 200 ml of anhydrous ethanol solvent, and ultrasonically dispersed for 2 h. The Schiff base ligand obtained in step (1) was added dropwise to the MCM-41 molecular sieve dispersion. After stirring and refluxing at 75° C. for 18 h, it was washed with anhydrous ethanol until neutral, and dried in a vacuum drying oven at 75° C. for 18 h to obtain a bifunctional MCM-41 molecular sieve.
[0035] Embodiment 3:
[0036] (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function:
[0037] 0.019 mol of 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane and 0.019 mol of 2,4-dihydroxybenzaldehyde were dispersed in 150 ml of anhydrous methanol, and then 0.15 ml of 1.5 mol / l glacial acetic acid was added to the mixed solution. Under the protection of helium gas, the mixture was stirred in an oil bath at 85°C for 24 hours to obtain a Schiff base ligand dispersion.
[0038] (2) Preparation of bifunctional MCM-41 molecular sieve:
[0039] 1.4 g of MCM-41 molecular sieve was dispersed in 250 ml of anhydrous methanol solvent, and ultrasonically dispersed for 2.5 h. The Schiff base ligand obtained in step (1) was added dropwise to the MCM-41 molecular sieve dispersion. After stirring and refluxing at 85° C. for 27 h, it was washed with anhydrous methanol until neutral, and dried in a vacuum drying oven at 60° C. for 27 h to obtain a bifunctional MCM-41 molecular sieve.
[0040] Embodiment 4:
[0041] (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function:
[0042] 0.023 mol of ureapropyltrimethoxysilane and 0.023 mol of 2-hydroxy-1-naphthaldehyde were dispersed in 200 ml of anhydrous toluene, and then 0.2 ml of 5 mol / l glacial acetic acid was added to the mixture. Under nitrogen protection, the mixture was heated and stirred at 90°C for 36 hours to obtain a Schiff base ligand dispersion.
[0043] (2) Preparation of bifunctional MCM-41 molecular sieve:
[0044] 1.5 g of MCM-41 molecular sieve was dispersed in 300 ml of anhydrous toluene solvent and ultrasonically dispersed for 3 h. The Schiff base ligand obtained in step (1) was added dropwise to the MCM-41 molecular sieve dispersion. After stirring and refluxing at 90° C. for 36 h, it was washed with anhydrous toluene until neutral, and dried in a vacuum drying oven at 80° C. for 36 h to obtain a bifunctional MCM-41 molecular sieve.
[0045] The specific steps of the adsorption experiment of aluminum ions by the bifunctional MCM-41 molecular sieve prepared by the present invention are as follows: 10 mg of the adsorbent obtained in Example 1, Example 2, Example 3, and Example 4 and 10 mg of the common commercially available MCM-41 molecular sieve are weighed as a comparative example, and placed in a conical flask containing 50 ml of a 120 mg / L aluminum ion solution, stirred at 45° C. for 4 hours, then centrifuged for 20 minutes, the supernatant is taken, and the residual aluminum ion concentration in the solution is detected by the GB-T5750.6-2006 chrome azure S spectrophotometry method, and the adsorption capacity of the bifunctional MCM-41 molecular sieve for aluminum ions is calculated, and the results are shown in Table 1. It can be seen from Table 1 that the bifunctional MCM-41 molecular sieve prepared according to the technical solution provided by the present invention has a more excellent aluminum ion adsorption performance, because after the MCM-41 molecular sieve is functionalized, its surface has nitrogen-containing, oxygen-containing and other electron-donating groups, which can coordinate and chelate with aluminum ions.
[0046] Table 1 Adsorption performance of bifunctional MCM-41 molecular sieve for aluminum ions
[0047] sample Adsorption capacity (mg / g) Example 1 120.28 Example 2 99.8 Example 3 84.2 Example 4 70.21 Comparative Example 11.21
[0048] The specific steps of the fluorescence detection experiment of aluminum ions by the bifunctional MCM-41 molecular sieve prepared by the present invention are as follows: 25 mg of the adsorbent obtained in Example 1, Example 2, Example 3, and Example 4 are weighed respectively, placed in a 50 ml volumetric flask, 2 ml is extracted into a cuvette using a pipette, and its fluorescence is measured using a fluorescence spectrophotometer. Then, 5 μL of 0.02 mol metal nitrate solution is added dropwise, and its fluorescence is measured using a fluorescence spectrophotometer. The results are shown in FIG. Figure 5 The detection limit of aluminum ions by the bifunctional MCM-41 molecular sieve is shown in Table 2. As can be seen from Table 2, according to the technical solution provided by the present invention, the detection limit of aluminum ions by the bifunctional MCM-41 molecular sieve obtained is much lower than the detection limit of aluminum ions in drinking water specified in the "Sanitary Standard for Drinking Water" (GB5749-2022). 3+ The content (7.4×10 -6 mol / L), indicating that the bifunctional MCM-41 molecular sieve prepared by the method of the present invention has good sensitivity to aluminum ions. This is because after the MCM-41 molecular sieve is functionalized with functional groups having photoluminescent properties, the groups containing nitrogen, oxygen and other fluorescent properties in the Schiff base compound coordinate with aluminum ions, thereby inhibiting isomerization and photoinduced electron transfer, thereby enhancing the fluorescence intensity and achieving the effect of highly sensitive detection of aluminum ions.
[0049] Table 2 Detection performance of bifunctional MCM-41 molecular sieve for aluminum ions
[0050] sample Detection limit (mol / L) Example 1 <![CDATA[2.323×10 -6 ]]> Example 2 <![CDATA[2.921×10 -6 ]]> Example 3 <![CDATA[5.234×10 -6 ]]> Example 4 <![CDATA[7.336×10 -6 ]]> Comparative Example -
[0051] Depend on Figure 1 It can be seen that the 2-hydroxy-1-naphthaldehyde functionalized MCM-41 molecular sieve is in rod-like and spherical stacking states.
[0052] Depend on Figure 2 It can be seen that the 2-hydroxy-1-naphthaldehyde functionalized MCM-41 molecular sieve has a hexagonal pore structure.
[0053] Depend on Figure 3 It can be seen that the characteristic diffraction peaks of MCM-41 molecular sieve appear at 2θ=2.2°, 2θ=3.83° and 2θ=4.42°. By comparison, it is found that the characteristic diffraction peaks of MCM-41 molecular sieve functionalized with 2-hydroxy-1-naphthaldehyde correspond to the (100), (110) and (200) crystal planes, respectively, indicating that the functionalization process of MCM-41 molecular sieve does not affect its pore structure.
[0054] Depend on Figure 4It can be seen that the MCM-41 molecular sieve functionalized with 2-hydroxy-1-naphthaldehyde contains not only carbon and oxygen elements, but also nitrogen elements, indicating that 2-hydroxy-1-naphthaldehyde has been successfully grafted onto the MCM-41 molecular sieve. After the adsorption of aluminum ions, the presence of aluminum elements can be seen, indicating that the MCM-41 molecular sieve functionalized with 2-hydroxy-1-naphthaldehyde has successfully adsorbed aluminum ions.
[0055] The parts not described in detail in this application are all existing conventional technologies and will not be described in detail here.
[0056] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.
Claims
1. A method for preparing a bifunctional MCM-41 molecular sieve for adsorption and detection of aluminum ions, characterized in that: The following steps are involved: (1) Preparation of Schiff base ligands with fluorescence properties and metal ion chelating function: Disperse 0.011-0.023 mol of a silane coupling agent and 0.011-0.023 mol of an organic compound in 50-200 ml of an organic solvent, then add 0.05-0.2 ml of 1-5 mol / l glacial acetic acid to the mixed solution, and heat and stir at 60-90° C. for 12-36 hours under the protection of an inert gas to obtain a Schiff base ligand dispersion; (2) Preparation of bifunctional MCM-41 molecular sieve: Disperse 1-1.5 g of MCM-41 molecular sieve in 100-300 ml of organic solvent, and perform ultrasonic dispersion for 1-3 hours to obtain a MCM-41 molecular sieve dispersion liquid. Add the Schiff base ligand obtained in step (1) dropwise into the MCM-41 molecular sieve dispersion liquid. Stir and reflux at 60-90° C. for 12-36 hours, and wash with an organic solvent until neutral. Dry in a vacuum drying oven at 50-80° C. for 12-36 hours to obtain a bifunctional MCM-41 molecular sieve.
2. The method for preparing a bifunctional MCM-41 molecular sieve for adsorption and detection of aluminum ions according to claim 1, characterized in that: In the step (1), the silane coupling agent is selected from one of ureapropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.
3. The method for preparing a bifunctional MCM-41 molecular sieve for adsorption and detection of aluminum ions according to claim 1, characterized in that: In the step (1), the organic compound is selected from one of 2-hydroxy-1-naphthaldehyde, 2,4-dihydroxybenzaldehyde, 8-quinolinecarboxaldehyde and salicylaldehyde.
4. The method for preparing a bifunctional MCM-41 molecular sieve for adsorption and detection of aluminum ions according to claim 1, characterized in that: The inert gas in step (1) is one of nitrogen, argon and helium.
5. The method for preparing a bifunctional MCM-41 molecular sieve for adsorption and detection of aluminum ions according to claim 1, characterized in that: The organic solvent is one of anhydrous dimethyl sulfoxide, anhydrous ethanol, anhydrous methanol and anhydrous toluene.