Application of metal organic framework material MOFs in degradation of organophosphorus pesticide

Abstract

The invention belongs to the technical field of metal organic framework materials and pesticide degradation, and particularly relates to application of a metal organic framework material MOFs in degradation of organophosphorus pesticides. After the metal organic framework material reacts with acephate under an alkaline condition, the structure of acephate is broken, so that macromolecular toxic compounds are converted into small molecular compounds, and the purpose of degrading acephate is achieved. And meanwhile, the metal organic framework material has the advantages of quick response, high sensitivity, high degradation rate and the like on degradation of acephate, and can effectively, quickly, massively and even completely degrade organophosphorus pesticides, especially acephate, so that the metal organic framework material has great application potential in the environmental protection aspect of organophosphorus pesticide degradation.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework materials and pesticide degradation, and particularly relates to an application of metal organic framework materials MOFs in the degradation of organophosphorus pesticides. Background Art

[0002] Acephate (O,S-dimethylacetylthiophosphoramide, Acephate) is a highly effective, low-toxic, and low-cost systemic organophosphorus insecticide widely used for pest control in food crops such as rice and wheat, as well as cash crops and vegetables such as cotton, tobacco, and tea. Acephate toxicizes pests by inhibiting acetylcholinesterase (AChE) activity. Acephate is also highly water-soluble, easily contaminating groundwater and soil. It is also readily absorbed by plants and accumulates in their edible parts, leading to its enrichment in the food chain. Furthermore, existing literature indicates that acephate exhibits neurotoxicity, reproductive toxicity, and developmental toxicity in non-target organisms such as fish, rats, birds, and humans. Therefore, the removal of residual acephate in the environment is urgent. Currently, widely used degradation methods include microbial degradation, photocatalysis, ultrasonic ozonation, and high-energy irradiation. Microbial degradation is considered a promising approach, but its degradation capacity is highly limited by the isolated microorganisms and the environment in which it is found, and degradation often takes days or even weeks. Photocatalysis is also a popular technology for degrading acephate, but it often relies on high-intensity ultraviolet light, which significantly increases the degradation threshold. Ultrasonic ozonation and high-energy irradiation also face application challenges. Therefore, there is an urgent need to develop a technology that can quickly, easily, and efficiently degrade acephate in large quantities. Summary of the Invention

[0003] The object of the present invention is to provide a technology that can effectively, quickly and in large quantities degrade organophosphorus pesticides, especially acephate. The technical solution of the present invention is based on the application of metal organic framework materials MOFs in the degradation of organophosphorus pesticides. After the metal organic framework material reacts with acephate under alkaline conditions, it will cause the structure of acephate to break, converting it from a large molecular toxic compound to a small molecular compound, thereby achieving the purpose of degrading acephate. At the same time, the metal organic framework material has the advantages of rapid response, high sensitivity and fast degradation rate to the degradation of acephate. Specifically, the present invention is implemented by adopting the following technical solutions:

[0004] The application of the metal-organic framework material MOFs in the degradation of organophosphorus pesticides described in the present invention is that the metal-organic framework material MOFs reacts with acephate in the presence of morpholine base, so that the PO bond in the acephate structure is broken, and the acephate is converted from a large molecular toxic substance to a small molecular substance. The organophosphorus pesticide includes at least one of methamidophos and acephate.

[0005] For the above-mentioned application, it is preferred that the metal organic framework material MOFs is Zr-MOF-808.

[0006] For the above-mentioned application, it is preferred that the morpholine base comprises at least one of morpholine, N-methylmorpholine, N-ethylmorpholine (NEM), N-n-propylmorpholine, and 4-methylmorpholine.

[0007] As a more preferred application method, the following method steps can be adopted: preparing an aqueous solution of an organophosphorus pesticide containing morpholine base, adding MOFs thereto, and stirring for reaction.

[0008] In the above-mentioned application, it is more preferred that in the aqueous solution of the organophosphorus pesticide, the concentration of morpholine base in the range of 0.01-0.5M can act as a co-catalyst. When the concentration is in the range of 0.04-0.3M, the pesticide can be completely degraded. The selection of 0.04-0.08, especially 0.04-0.06M, is based on economic and environmental considerations. The pesticide can be degraded when the concentration of the organophosphorus pesticide is in the range of 20-100mM, and the pesticide can be completely degraded when the concentration is in the range of 20-40mM, especially 25mM-35mM.

[0009] Preferably, the mass-to-volume ratio of the MOFs to the organophosphorus pesticide aqueous solution is 3-6:1, preferably 4-5:1, mg / mL. Furthermore, the reaction time can be 1-30 minutes, preferably 5-20 minutes, and more preferably 10-15 minutes. Furthermore, the aqueous solution is preferably a deuterated aqueous solution to minimize the influence of experimental observations.

[0010] More preferably, for the above-mentioned application, the following method steps can be used: preparing a deuterated aqueous solution of acephate containing N-ethylmorpholine, placing 5 mg of MOF-808 and 1 mL of the deuterated aqueous solution of acephate in a reaction bottle, and stirring them magnetically to fully react; in the deuterated aqueous solution of acephate, the concentration of N-ethylmorpholine is 0.05 M, and the concentration of acephate is 25 mM.

[0011] Metal-organic framework materials (MOFs) are highly favored by researchers due to their excellent performance in adsorption, separation, catalysis and other fields. Zirconium-based MOF materials are excellent in activating coordinated organophosphorus compounds and decomposing the phosphate bonds of these compounds. Based on the phosphohydrolase-like activity of zirconium-based MOF materials, the metal-organic framework materials provided by the present invention can effectively, rapidly (within 15 minutes), and even completely degrade organophosphorus pesticides, especially acephate in large quantities. At the same time, the metal-organic framework materials MOFs provided by the present invention are simple to synthesize, and green synthesis can be completed in just one step and further used to degrade the organophosphorus pesticide acephate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a scanning electron microscope image of MOF-808.

[0013] Figure 2 This is a transmission electron microscope image of MOF-808.

[0014] Figure 3 This is the XPS image of MOF-808.

[0015] Figure 4 This is the FTIR image of MOF-808.

[0016] Figure 5 This is the MOF-808 synthesis flow chart.

[0017] Figure 6 This is a stacked diagram of the nuclear magnetic phosphorus spectra of acephate and its hydrolysis reaction.

[0018] Figure 7 This is the hydrolysis curve of acephate.

[0019] Figure 8 This is a stacked image of the H-NMR spectra of acephate and its control experiment.

[0020] Figure 9 This is a stacked image of the nuclear magnetic phosphorus spectra of acephate and its control experiment.

[0021] Figure 10 This is a stacked image of the nuclear magnetic phosphorus spectra of repeated experiments.

[0022] Figure 11 It is the hydrolysis histogram of repeated experiments. DETAILED DESCRIPTION

[0023] The following embodiments are further descriptions of the present invention to illustrate the technical content of the present invention, but the essential content of the present invention is not limited to the following embodiments. Ordinary technicians in this field can and should know that any simple changes or replacements based on the essential spirit of the present invention should fall within the scope of protection required by the present invention.

[0024] Example 1 Synthesis and characterization of metal-organic framework materials

[0025] Synthesis of MOF-808:

[0026] Zirconium chloride (0.6991 g, 3 mmol) and trimesic acid (0.2101 mg, 1 mmol) were added to a 50 mL round-bottom flask, followed by 17.3 mL of deionized water and 2.7 mL of formic acid. The mixed solution was refluxed at 120°C for 24 hours. After cooling to room temperature, the white product was collected by centrifugation and washed three times with methanol. Finally, it was dried under vacuum at 120°C for 12 hours. The resulting product is the metal-organic framework material Zr-MOF-808. The synthesis does not use highly toxic organic solvents (such as the commonly used DMF) and is performed at room temperature and atmospheric pressure, conforming to the principles of green chemistry.

[0027] The MOF-808 material synthesized in a water / formic acid mixed solvent system is spherical and has uniform particle size. Figure 1 、 Figure 2 As shown. XPS image ( Figure 3 ) shows that the synthesized material contains C, O, and Zr elements, which are consistent with the elements of MOF-808 material reported in the literature. FTIR image ( Figure 4 ) shows, 658 cm -1 The absorption peak at 1380 cm is attributed to the stretching symmetry of the Zr-O bond in MOF-808. -1 and 1619 cm -1 The absorption peak at corresponds to the COO - Symmetric and asymmetric stretching vibrations of functional groups, located at 1443 cm -1 and 1568 cm -1 The absorption peak corresponds to the vibration of the C=C bond of the benzene ring in the organic ligand.

[0028] Example 2 Hydrolysis and Characterization of Acephate

[0029] 1. Hydrolysis activity test

[0030] To evaluate the phosphohydrolase-like activity of Zr-MOF-808, nuclear magnetic resonance spectroscopy was used to monitor the catalytic conversion of acephate as a substrate. In a batch experiment, 5 mg of MOF-808 and 1 mL of acephate-d (0.05 M) NEM (N-Ethylmorpholine) solution were placed in a 2 mL reaction vial and magnetically stirred to allow for complete reaction. The mixture was removed at regular intervals and filtered through a 0.22 μm filter. The filtrate was then transferred to an NMR tube for NMR spectroscopy.

[0031] like Figure 6 As shown in Figure 1, the characteristic peak shift of the nuclear magnetic phosphorus spectrum of acephate in deuterated aqueous solution is at 33 ppm. As the reaction time increases, the peak area ratio at 33 ppm gradually decreases, indicating that the content of acephate in the reaction system gradually decreases. This is also consistent with the fact that new peaks appear at 24 ppm and -3.6 ppm. The hydrolysis conversion curve of acephate was drawn based on the ratio of the peak area at 33 ppm to the total phosphorus spectrum peak area, as shown in Figure 1. Figure 7 shown.

[0032] 2. Control experiment

[0033] To evaluate the effect of NEM on hydrolytic activity, we performed a modified version of the hydrolytic activity assay. In a control experiment, 5 mg of MOF-808 was added to a 1 mL deuterated aqueous solution of acephate (25 μmol) in a glass reaction vial. Half of the vials (multiple replicates) were left without NEM and allowed to react fully under magnetic stirring. After 15 minutes of reaction, the mixture was removed and filtered through a 0.22 μm filter. The filtrate was transferred to an NMR tube for NMR spectroscopy.

[0034] Combined with H NMR spectroscopy (such as Figure 8 ) and NMR phosphorus spectra (such as Figure 9 ) combined analysis showed that when NEM and MOF-808 were added separately to a deuterated aqueous solution of acephate, acephate did not decompose, as evidenced by the absence of new peaks in the NMR phosphorus spectrum. Only under alkaline conditions, where NEM acts as a co-catalyst, did MOF-808 demonstrate catalytic activity for acephate, as evidenced by the disappearance of the characteristic acephate peak at 33 ppm and the appearance of new peaks at 24 ppm and -3.6 ppm.

[0035] In the figure, Acephate represents the pesticide sample alone, Acephate + NEM represents the pesticide plus NEM (without the MOF-808 catalyst), Acephate + MOF-808 represents the pesticide plus MOF-808 (without NEM), and Acephate + MOF-808 + NEM represents the pesticide plus both NEM and MOF-808. Adding NEM or MOF-808 alone does not degrade the pesticide, as evidenced by the persistence of the characteristic peak at 33 ppm in the NMR phosphorus spectrum. The NMR phosphorus peak at 36 ppm remains characteristic of the pesticide, and the shift from 33 ppm to 36 ppm is due to the addition of NEM. Adding NEM alone does not degrade the pesticide, as evidenced by the absence of a new peak in the H NMR spectrum.

[0036] 3. Repeat the experiment

[0037] Multiple experiments were conducted to eliminate the accidental nature of the experiment. For the experimental steps, refer to the hydrolysis activity experiment. Figure 10 、 Figure 11 After three repeated experiments, no characteristic peak of acephate appeared at 33 ppm, indicating that acephate had been completely degraded after 15 min of catalyst action, and the repeatability was good.

[0038] The test results show that MOF-808 can completely degrade acephate in the presence of NEM. MOF-808 has a relatively fast degradation rate (within 15 minutes) for acephate in the presence of NEM.

[0039] Example 3

[0040] The method of Example 2 was adopted, except that a deuterated aqueous solution containing 0.02 M NEM (N-Ethylmorpholine) and 30 mM acephate was prepared.

[0041] Example 4

[0042] The method of Example 2 was adopted, except that the solution contained 0.1 M NEM (N-Ethylmorpholine) and 35 mM deuterated acephate in water.

[0043] Example 5

[0044] The method of Example 2 was adopted, except that a deuterated aqueous solution containing 0.2 M NEM (N-Ethylmorpholine) and 40 mM acephate was prepared.

[0045] Example 6

[0046] The method of Example 2 was adopted, except that a deuterated aqueous solution containing 0.4 M NEM (N-Ethylmorpholine) and 50 mM acephate was prepared.

[0047] In Examples 3-6, although the concentrations of NEM and acephate were changed, MOF-808 still had good catalytic activity for degrading acephate.

[0048] It should be noted that the technical contents of the present invention described above are only for the purpose of explaining and illustrating the technical essence of the present invention to enable those skilled in the art to understand the technical essence of the present invention. Therefore, the technical contents described above are not intended to limit the substantial protection scope of the present invention. The substantial protection scope of the present invention shall be based on the claims. Those skilled in the art should be aware that any modifications, equivalent substitutions, and improvements based on the substantial spirit of the present invention shall fall within the substantial protection scope of the present invention.

Claims

1. Application of metal organic framework materials MOFs in the degradation of organophosphorus pesticides, characterized in that: In the presence of morpholine base, the metal organic framework material MOFs reacts with the organophosphorus pesticide to break the PO bond in the acephate structure, and the acephate is converted from a large molecular toxic substance to a small molecular substance. The organophosphorus pesticide includes at least one of methyl parathion and acephate.

2. The use according to claim 1, characterized in that The metal organic framework material MOFs is Zr-MOF-808.

3. The use according to claim 1, characterized in that The morpholine base includes at least one of morpholine, N-methylmorpholine, N-ethylmorpholine, N-n-propylmorpholine, and 4-methylmorpholine.

4. The use according to claim 1, wherein The following method steps are adopted: preparing an organic phosphorus pesticide aqueous solution containing morpholine base, adding MOFs therein, and stirring for reaction.

5. The use according to claim 4, characterized in that In the aqueous solution of the organophosphorus pesticide, the concentration of morpholine base is 0.01-0.5 M, preferably 0.04-0.3 M, more preferably 0.04-0.08 M, and most preferably 0.04-0.06 M. The concentration of the organophosphorus pesticide is 20-100 mM, preferably 20-40 mM, and more preferably 25-35 mM.

6. The use according to claim 4, characterized in that The mass volume ratio of the MOFs to the organophosphorus pesticide aqueous solution is 3-6:1, mg / mL.

7. The use according to claim 4, characterized in that The reaction time is 1-30 min, preferably 5-20 min, more preferably 10-15 min.

8. The use according to any one of claims 4 to 7, characterized in that The aqueous solution is a deuterated aqueous solution.

9. The use according to claim 4, characterized in that The following method steps were used: a deuterated aqueous solution of acephate containing N-ethylmorpholine was prepared, 5 mg of Zr-MOF-808 and 1 mL of the deuterated aqueous solution of acephate were placed in a reaction bottle, and the mixture was fully reacted by magnetic stirring.

10. The use according to claim 9, characterized in that In the deuterated aqueous solution of acephate containing N-ethylmorpholine, the concentration of N-ethylmorpholine is 0.05 M and the concentration of acephate is 25 mM.

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