A MOF-Fe material, its preparation method and application at normal temperature and pressure

Abstract

The present invention relates to an aMOF-Fe material, a preparation method thereof at normal temperature and pressure, and an application thereof, which includes the following steps carried out at normal temperature and pressure: adding trimesic acid to a sodium hydroxide solution and stirring to obtain a clear solution A; dissolving ferrous sulfate heptahydrate in water to obtain a clear light green solution B; slowly adding the solution A to the solution B and stirring to obtain a mixed liquid C; adding a hydrogen peroxide solution to the mixed liquid C and stirring at room temperature to finally obtain a crude aMOF-Fe suspension; centrifuging the crude aMOF-Fe suspension, discarding the supernatant, washing the precipitate with water and ethanol in sequence and centrifuging, and freeze-drying to obtain purified aMOF-Fe. Compared with the prior art, the present invention provides a simple, easy-to-implement, green, low-toxic, high-synthesis-efficiency and high-yield synthesis method of amorphous MOF-Fe (abbreviated as aMOF-Fe) derived from MIL-100(Fe), and uses the provided aMOF-Fe for efficiently adsorbing and catalyzing hydrogen peroxide to remove tetracycline antibiotics in water.

Description

Technical Field

[0001] The present invention relates to the technical fields of environmental functional materials and water pollution control, and in particular to a method for preparing amorphous MOF-Fe (aMOF-Fe) materials derived from MIL-100(Fe) under normal temperature and pressure, and a method and application for adsorbing and catalytically degrading tetracycline antibiotics in water. Background Art

[0002] Due to their broad-spectrum effectiveness, high antibacterial activity, and low usage cost, tetracycline antibiotics are widely used for the prevention of human and animal diseases. Since tetracycline antibiotics are not easily absorbed and metabolized in the digestive systems of humans and animals, approximately 70% to 90% of tetracycline antibiotics will enter sewage in the form of the parent compound, and the removal efficiency during the sewage treatment process is usually low (most are below 50%), and the wastewater and membrane concentrates generated during the antibiotic production process can even reach higher concentration levels. After being treated by sewage treatment plants and discharged into natural water bodies, tetracycline antibiotics will further pollute the aquatic ecosystem and soil ecosystem. In addition, the unremoved tetracycline antibiotics will further form disinfection by-products such as N-nitrosodimethylamine during chlorination disinfection, which have potential carcinogenicity and mutagenicity.

[0003] In recent years, the research on the degradation of organic pollutants in aqueous solutions using the integrated technology of adsorption and advanced oxidation has attracted much attention. This technology can organically combine the adsorption method and the advanced oxidation method, give full play to their respective advantages, and achieve the effective enrichment and efficient degradation of pollutants. The materials required in the technology have a high specific surface area and high porosity, and the resulting good adsorption performance can promote the mass transfer of organic pollutants to the material surface, thereby effectively improving the adsorption effect of the material on organic pollutants. On the material surface, advanced oxidation can achieve the degradation of the organic pollutants adsorbed by the material.

[0004] Iron-based metal-organic frameworks have been widely studied and applied due to their relatively low raw material cost, low toxicity, and high catalytic performance. Among them, MIL-100(Fe) has become a candidate that has received sufficient attention for various applications due to its excellent water stability. However, the traditional hydrothermal synthesis of MIL-100(Fe) usually requires conditions such as high temperature (above 140°C), strong acids (HF and HNO3), and long reaction times. Therefore, it is of great significance to develop a simple, easy-to-implement, green, and low-toxic synthesis method. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the above-mentioned existing technologies, and provide a simple, easy-to-implement, green, low-toxic, high-synthesis-efficiency and high-yield synthesis method of amorphous MOF-Fe (aMOF-Fe) derived from MIL-100(Fe), and the provided aMOF-Fe is used for efficiently adsorbing and catalyzing hydrogen peroxide to remove tetracycline antibiotics in water.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] In the first aspect of the present invention, a method for preparing aMOF-Fe under normal temperature and pressure is provided, including the following steps:

[0008] S1: Add trimesic acid to a sodium hydroxide solution, and stir to obtain a clear solution A;

[0009] S2: Dissolve ferrous sulfate heptahydrate in water to obtain a clear light green solution B;

[0010] S3: Slowly add the solution A to the solution B, and stir to obtain a mixed liquid C;

[0011] S4: Add a hydrogen peroxide solution to the mixed liquid C, and stir at room temperature to finally obtain a crude aMOF-Fe suspension;

[0012] S5: Centrifuge the crude aMOF-Fe suspension, then discard the supernatant, wash the precipitate with water and ethanol in sequence and centrifuge, and freeze-dry the obtained solid to obtain purified aMOF-Fe.

[0013] Further, in S1, the molar ratio of the added trimesic acid to sodium hydroxide is 1:3;

[0014] In the solution A, the concentration of trimesic acid is 475-640 mmol / L, and the concentration of sodium hydroxide is 1425-1920 mmol / L.

[0015] Further, in S2, the molar concentration of ferrous sulfate heptahydrate in the solution B is 160-570 mmol / L.

[0016] Further, the molar ratio of the added ferrous sulfate heptahydrate, trimesic acid, sodium hydroxide, and hydrogen peroxide is 1.5:1:3:(0.3-3).

[0017] Further, in S1 to S4, the stirring speed is 200-800 rpm.

[0018] Further, after S3, add the hydrogen peroxide solution after an interval of 0.5-120 min, and the stirring time at room temperature is 1-4 hours.

[0019] Further, in S4, the addition of hydrogen peroxide during the synthesis of MIL-100(Fe) causes the Fenton reaction of Fe(II), promoting the oxidation of Fe(II) to produce Fe(III), thereby rapidly generating defective [Fe(III)3(μ-O)(CO2)6] SBUs.

[0020] Further, the mass concentration of hydrogen peroxide is 0.1% - 30%.

[0021] Further, in S5, the centrifugation speed is 6000 rpm, and the conditions for freeze-drying are -45°C to -55°C for 24 to 48 hours.

[0022] The second aspect of the present invention provides a MOF-Fe material prepared by the above method.

[0023] The third aspect of the present invention provides an application of the above MOF-Fe material, applying the MOF-Fe to the adsorption and catalytic degradation of tetracycline antibiotics in water under dark reaction conditions.

[0024] The main mechanism of the present invention is as follows: The synthesis of MIL-100(Fe) is mainly the combination of Fe(III) and sodium trimesate. In this synthesis method, if hydrogen peroxide is not added, the slow oxidation of Fe(II) in ferrous sulfate by air can promote the more perfect formation of [Fe(III)3(μ-O)(CO2)6] SBUs generated by the combination of Fe(III) and sodium trimesate, thereby producing MIL-100(Fe) with high crystallinity. The addition of hydrogen peroxide during the synthesis of MIL-100(Fe) is equivalent to the Fenton reaction of Fe(II), promoting the oxidation of Fe(II) to produce a large amount of Fe(III), thereby rapidly generating defective [Fe(III)3(μ-O)(CO2)6] SBUs (SBU is secondary building unit, that is, the secondary building unit). Controlling the addition time and dosage of hydrogen peroxide can not only retain part of the specific surface area of MIL-100(Fe), but also greatly accelerate the synthesis time of the material and improve the space-time yield of the material. In addition, the hydroxyl radicals generated during the Fenton process will attack trimesic acid, generating hydroxylated trimesic acid and further generating hydroxylated modified aMOF-Fe, providing stronger acidic sites and improving the catalytic reaction.

[0025] Compared with the prior art, the present invention has the following technical advantages:

[0026] (1) The method for preparing aMOF-Fe of the present invention has greatly improved synthesis efficiency and significantly increased yield compared with the room-temperature synthesis of MIL-100(Fe).

[0027] (2) The method for preparing aMOF-Fe of the present invention has the advantages of low cost, simple operation, good repeatability, etc.;

[0028] (3) The aMOF-Fe prepared by the present invention has excellent adsorption and catalytic effects on antibiotics and has broad industrial application prospects. Description of the Drawings

[0029] Figure 1 It is the scanning electron microscope photograph of aMOF-Fe-1 in the embodiment of the present invention;

[0030] Figure 2 It is the XRD pattern of aMOF-Fe-1 and aMOF-Fe-2 in the embodiment of the present invention;

[0031] Figure 3 It is the effect diagram of aMOF-Fe-1 adsorbing oxytetracycline hydrochloride with different concentrations in the embodiment of the present invention;

[0032] Figure 4 It is the effect diagram of aMOF-Fe-1 adsorbing and degrading oxytetracycline hydrochloride, tetracycline, doxycycline hydrochloride, and chlortetracycline hydrochloride in the embodiment of the present invention. Detailed Embodiments

[0033] The present invention will be described in detail below with reference to the drawings and specific embodiments. The preparation means, materials, structures, or composition ratios and other features not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0034] Example 1

[0035] The method for preparing aMOF-Fe at normal temperature and pressure in this example includes the following steps:

[0036] (1) Dissolve 228 mg of sodium hydroxide in 4.0 g of water, and then add 399.3 mg of trimesic acid. Stir magnetically until the powder is completely dissolved to obtain solution A.

[0037] (2) First, measure 16.0 g of water in a reagent bottle, add 792.44 mg of ferrous sulfate heptahydrate, and stir magnetically until completely dissolved to obtain solution B.

[0038] (3) Slowly add solution A dropwise to solution B and stir (add it all within 30 seconds). When the addition of all solution A and solution B is completed, record the reaction time as zero at this time.

[0039] (4) After half a minute of reaction, 10 mL of 57 mM hydrogen peroxide was added to the solution. After 2 hours of reaction, the solution was transferred to a 50 mL centrifuge tube and centrifuged at 6000 rpm for 3 - 5 minutes. The supernatant was discarded, then 30 mL of pure water was added and sonicated for 30 minutes. After centrifuging at 6000 rpm for 5 minutes, the supernatant was discarded. After repeating the operation 3 times, the material was washed with ethanol 3 times.

[0040] (5) The finally obtained solid was freeze-dried for 24 hours to obtain purified aMOF-Fe-1.

[0041] As Figure 1 shown, aMOF-Fe-1 is mainly composed of many irregular particles with an average size of 100 nm piled up.

[0042] As Figure 2 shown, the X-ray diffraction peaks of aMOF-Fe-1 indicate that the crystallinity of aMOF-Fe-1 has decreased significantly compared to MIL-100(Fe).

[0043] Example 2

[0044] In this example, the method for preparing aMOF-Fe at normal temperature and pressure includes the following steps:

[0045] (1) 228 mg of sodium hydroxide was dissolved in 4.0 g of water, and then 399.3 mg of trimesic acid was added. After magnetic stirring until the powder was completely dissolved, solution A was obtained.

[0046] (2) First, 16.0 g of water was measured into a reagent bottle, and 792.44 mg of ferrous sulfate heptahydrate was added. After magnetic stirring until completely dissolved, solution B was obtained.

[0047] (3) Solution A was added dropwise to solution B and stirred (added within 30 seconds). When the addition of all of solution A and solution B was completed, the reaction time was recorded as zero at this time.

[0048] (4) After half a minute of reaction, 10 mL of 285 mM hydrogen peroxide was added to the solution. After 1 hour of reaction, the solution was transferred to a 50 mL centrifuge tube and centrifuged at 6000 rpm for 3 - 5 minutes. The supernatant was discarded, then 30 mL of pure water was added and sonicated for 30 minutes. After centrifuging at 6000 rpm for 5 minutes, the supernatant was discarded. After repeating the operation 3 times, the material was washed with ethanol 3 times.

[0049] (5) The finally obtained solid was freeze-dried for 24 hours to obtain purified aMOF-Fe, named aMOF-Fe-2.

[0050] As Figure 2As shown, the X-ray diffraction peaks of aMOF-Fe-2 indicate that the crystallinity of aMOF-Fe-2 has significantly decreased compared to MIL-100(Fe).

[0051] Example 3

[0052] The method for preparing aMOF-Fe at normal temperature and pressure in this example includes the following steps:

[0053] (1) Dissolve 6.840 g of sodium hydroxide in 120 g of water, then add 12 g of trimesic acid, and stir magnetically until the powder is completely dissolved to obtain solution A.

[0054] (2) First, measure 480 g of water into a reagent bottle, add 23.77 g of ferrous sulfate heptahydrate, and stir magnetically until completely dissolved to obtain solution B.

[0055] (3) Slowly add solution A drop by drop to solution B and stir (add it all within 30 seconds). When the addition of all of solution A and solution B is completed, record the reaction time as zero at this moment.

[0056] (4) After half a minute of reaction, add 300 mL of 57 mM hydrogen peroxide to the solution. After reacting for 2 hours, transfer the solution to a 50 mL centrifuge tube, centrifuge at 6000 rpm for 3 - 5 minutes, discard the supernatant, then add 30 mL of pure water and sonicate for 30 minutes, centrifuge at 6000 rpm for 5 minutes and discard the supernatant. Repeat the operation 3 times and then wash the material 3 times with ethanol.

[0057] (5) The finally obtained solid is freeze-dried for 48 hours to obtain purified aMOF-Fe-1, with a yield of 20.95 g.

[0058] Example 4

[0059] The method for preparing aMOF-Fe at normal temperature and pressure in this example includes the following steps:

[0060] (1) Dissolve 6.840 g of sodium hydroxide in 90 g of water, then add 12 g of trimesic acid, and stir magnetically until the powder is completely dissolved to obtain solution A.

[0061] (2) First, measure 120 g of water into a reagent bottle, add 23.77 g of ferrous sulfate heptahydrate, and stir magnetically until completely dissolved to obtain solution B.

[0062] (3) Slowly add solution A drop by drop to solution B and stir (add it all within 30 seconds). When the addition of all of solution A and solution B is completed, record the reaction time as zero at this moment.

[0063] (4) After half a minute of reaction, 30 mL of 570 mM hydrogen peroxide was added to the solution. After 2 hours of reaction, the solution was transferred to a 50 mL centrifuge tube and centrifuged at 6000 rpm for 3 - 5 minutes. The supernatant was discarded, then 30 mL of pure water was added and sonicated for 30 minutes. After centrifuging at 6000 rpm for 5 minutes, the supernatant was discarded. This operation was repeated 3 times, and then the material was washed 3 times with ethanol.

[0064] (5) The finally obtained solid was freeze-dried for 48 hours to obtain purified aMOF-Fe-1 with a yield of 22.50 g.

[0065] Example 5

[0066] This example is about the application of aMOF-Fe-1 for highly efficient adsorption of oxytetracycline hydrochloride in water.

[0067] For the adsorption study, 10 mg of aMOF-Fe-1 was added to 50 mL of 10, 25, 50, 100 mg / L oxytetracycline hydrochloride solutions without adjusting the pH value. The reaction was carried out on a magnetic stirrer at a speed of 450 rpm. After a certain interval of time, 0.8 mL of the solution was taken and filtered through a 0.22 μm polyethersulfone filter head into a 2 mL centrifuge tube. 200 μL of the supernatant was taken to measure its absorbance at 354 nm (sweeping spectrum). The experiment was carried out in duplicate.

[0068] The results are as Figure 3 shown. For the 10 mg / L oxytetracycline hydrochloride solution, aMOF-Fe-1 can remove more than 99.9% of oxytetracycline hydrochloride within 90 minutes. For the 50 mg / L oxytetracycline hydrochloride solution, 0.2 g / L of aMOF-Fe-1 can remove 69.6% of oxytetracycline hydrochloride.

[0069] Example 6

[0070] This example is about the application of aMOF-Fe-1 for highly efficient adsorption and degradation of oxytetracycline hydrochloride in water.

[0071] 10 mg of aMOF-Fe-1 was added to 50 mL of 0.2 mM oxytetracycline hydrochloride, tetracycline, doxycycline hydrochloride, and chlortetracycline hydrochloride solutions with an initial pH value of 5. The reaction was carried out on a magnetic stirrer at a speed of 450 rpm. Two points were taken at the adsorption equilibrium (260 - 270 minutes). After adsorption equilibrium, 0.05 mL of 1 M hydrogen peroxide was added to the solution. At the 150-minute time point, 0.8 mL of the solution was filtered (0.22 μm polyethersulfone filter head) into a 2 mL centrifuge tube. 0.5 mL of the filtrate was taken into a 1.5 mL injection vial, and then 0.5 mL of methanol was added. After mixing, the concentration of the analyte was analyzed by HPLC.

[0072] The results are as Figure 4As shown, aMOF-Fe-1 can catalyze the activation of hydrogen peroxide and can remove at least 97% of tetracycline antibiotics.

[0073] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing aMOF-Fe under normal temperature and pressure, characterized in that, Including the following steps carried out at normal temperature and pressure: S1: Add trimesic acid to a sodium hydroxide solution and stir to obtain a clear solution A; S2: Dissolve ferrous sulfate heptahydrate in water to obtain a clear light green solution B; S3: Slowly add the solution A to the solution B and stir to obtain a mixed liquid C; S4: Add a hydrogen peroxide solution to the mixed liquid C and stir at room temperature to finally obtain a crude aMOF-Fe suspension; S5: Centrifuge the crude aMOF-Fe suspension, then discard the supernatant. Wash the precipitate with water and ethanol successively and centrifuge. Freeze-dry the obtained solid to obtain purified aMOF-Fe; In S1, the molar ratio of trimesic acid to sodium hydroxide added is 1:3; In the solution A, the concentration of trimesic acid is 475 - 640 mmol / L, and the concentration of sodium hydroxide is 1425 - 1920 mmol / L; In S2, the molar concentration of ferrous sulfate heptahydrate in the solution B is 160 - 570 mmol / L; The molar ratio of ferrous sulfate heptahydrate, trimesic acid, sodium hydroxide, and hydrogen peroxide added is 1.5:1:3:(0.3 - 3); After S3, add the hydrogen peroxide solution after an interval of 0.5 - 120 minutes, and stir at room temperature for 0.5 - 4 hours.

2. The method for preparing aMOF-Fe under normal temperature and pressure according to claim 1, wherein In S1 to S4, the stirring speed is 200 - 800 rpm.

3. A method for preparing aMOF-Fe at normal temperature and pressure according to claim 1, characterized in that, In S5, the centrifugation speed is 6000 rpm, and the conditions for freeze-drying are -45°C to -55°C for 24 - 48 hours.

4. An aMOF-Fe material prepared by the method according to any one of claims 1 to 3.

5. Use of the aMOF-Fe material as described in claim 4, characterized in that, Apply the aMOF-Fe under dark reaction conditions to adsorb and catalyze the degradation of tetracycline antibiotics in water by hydrogen peroxide.

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