Metal Mn-doped organic framework material for glyphosate degradation and synthesis method of metal Mn-doped organic framework material

Abstract

The invention discloses a metal Mn-doped organic framework material for glyphosate degradation and a synthesis method of the metal Mn-doped organic framework material, and belongs to the technical field of metal organic framework materials. According to the synthesis method, MOF-808 is used as a metal framework material, and Mn (NO3) 2.4 H2O is used as doping metal for green synthesis. The prepared material has the advantages of short response time, high selectivity and high degradation rate. After the metal framework material reacts with GP, P = O double bonds in the organophosphorus pesticide glyphosate structure are broken, macromolecular toxic substances are converted into micromolecular toxic substances, and the metal framework material has great potential in the aspect of environmental protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal organic framework materials, and in particular, relates to a metal Mn-doped organic framework material for glyphosate degradation and a synthesis method thereof. Background Art

[0002] Glyphosate (GP) is widely used in weed control due to its excellent herbicidal properties. So far, glyphosate has been used as a broad-spectrum herbicide for more than 50 years. However, the excessive use of glyphosate in the environment has led to an increasing amount of its residues in soil and drinking water, posing a serious threat to the environment and human health. The accumulation of glyphosate in the environment may disrupt the ecological balance, and long-term exposure to glyphosate may have potential carcinogenicity and genotoxicity to humans, and may damage the immune and endocrine systems. In addition, the toxicity of aminomethylphosphonic acid (AMPA), the main degradation intermediate of glyphosate (including natural degradation and advanced oxidation processes), has recently been found to be higher than that of glyphosate. More and more studies have shown that GP and AMPA may cause chromosomal aberrations in fish and carcinogenesis in human erythrocytes. As a new type of pollutant, glyphosate's content in the environment and its degradation process in wastewater treatment have attracted widespread attention. Therefore, it is crucial to establish a technology that can conveniently and quickly degrade GP while avoiding the generation of intermediate toxic byproducts.

[0003] With the development of detection technology, the current degradation methods of GP are becoming increasingly diverse. There are mainly plant absorption method, chemical degradation method, microbial degradation method and biodegradable product method. The plant absorption method uses the natural growth process of plants to degrade glyphosate without adding additional chemicals. However, the degradation ability of plants to glyphosate is relatively weak and can only play an auxiliary role. And not all plants can effectively degrade glyphosate, and specific plant species need to be selected. The chemical degradation method can usually quickly reduce the glyphosate content in the soil by adding certain chemicals. However, the added chemicals may cause new pollution risks to the environment. The microbial degradation method accelerates the degradation rate of glyphosate by introducing or increasing microorganisms in the soil, or using degradation agents added with microorganisms. This method uses the natural degradation ability of microorganisms and will not cause additional pollution to the environment. However, it takes a long time for microorganisms to degrade glyphosate, and the effect of microbial degradation may be affected by multiple factors such as soil conditions, temperature, humidity, etc., resulting in unstable effects. In addition, the degradation of glyphosate can also be achieved using various metal materials.

[0004] Metal-organic framework materials (MOFs) are increasingly favored by researchers due to their excellent performance and application prospects in adsorption, separation, catalysis, etc. Due to the presence of strong Lewis metal ions in the metal nodes of MOFs, it is very good at activating coordinated organophosphorus and decomposing the phosphate bonds of these organophosphorus. Therefore, the present invention provides a material for degrading glyphosate based on metal Mn-doped green synthetic MOF-808, which is used for rapid degradation of glyphosate. Summary of the invention

[0005] The purpose of the present invention is to provide a metal Mn doped organic framework material for glyphosate degradation and a synthesis method thereof. After the metal framework material reacts with GP, the structure of GP will be broken, so that it is converted from a macromolecular toxic compound to a small molecular non-toxic compound, thereby achieving the purpose of degrading GP. At the same time, the metal composite material has a rapid response to the degradation of GP, high sensitivity, and excellent degradation ability.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A metal Mn-doped organic framework material for glyphosate degradation has the following structure:

[0008]

[0009] The synthesis method of the metal Mn doped organic framework material adopts MOF-808 as the metal framework material and Mn(NO3)2·4H2O as the doping metal for green synthesis, and specifically comprises the following steps:

[0010] (1) Preparation of MOF-808;

[0011] (2) The pre-prepared MOF-808 is dispersed in N,N-dimethylformamide (DMF) containing Mn(NO3)2·4H2O, and then the mixture is placed in a round-bottom flask; under continuous stirring, the reaction is carried out under certain temperature conditions for a period of time, and then a solid is obtained by centrifugation (9500×g, 3min), and washed three times with DMF and acetone respectively; finally, it is vacuum dried at 100°C to prepare MOF-808-Mn (i.e., the metal Mn-doped organic framework material).

[0012] Furthermore, the specific steps of step (1) are as follows: zirconium chloride and 1,3,5-benzenetricarboxylic acid are added to a mixture of formic acid / water, placed in a round-bottom flask, condensed and refluxed at 120°C for 24 hours, centrifuged, fully rinsed with MeOH, and dried and activated at 120°C for 12 hours to obtain MOF-808.

[0013] Furthermore, in step (2), the ratio of MOF-808 to Mn(NO3)2·4H2O is 100 mg:4 mmol.

[0014] Furthermore, the reaction parameters in step (2) are: reaction at 85°C for 6 hours.

[0015] The test results show that:

[0016] 1) The MOF-808-Mn can completely degrade GP.

[0017] 2) The MOF-808-Mn has a faster degradation rate for GP without the addition of alkali.

[0018] The metal composite material of the present invention can quickly degrade the organophosphorus pesticide GP. When the material reacts with GP, the P=O double bond on the GP structure is destroyed, which causes the GP structure to break and form small molecules, thereby achieving the purpose of degrading GP. The material is prepared by two-step reaction, the synthesis is simple, and the yield is relatively high. The material for degrading GP disclosed by the present invention has the advantages of large degradation amount and rapid response in a pure water system without the need for additional addition of alkaline substances. When reacting with a GP solution, GP can be completely degraded within 5 minutes.

[0019] Beneficial effects of the present invention:

[0020] (1) The metal frame material provided by the present invention can effectively degrade GP.

[0021] (2) The metal composite material provided by the present invention is simple to synthesize and can be completed in just two steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1 This is the scanning electron microscope image of MOF-808.

[0024] Figure 2 This is the scanning electron microscope image of MOF-808-Mn.

[0025] Figure 3 This is the transmission electron microscopy image of MOF-808-Mn.

[0026] Figure 4 It is the X-ray diffraction pattern of MOF-808 and MOF-808-Mn.

[0027] Figure 5 It is the infrared spectra of MOF-808 and MOF-808-Mn.

[0028] Figure 6These are the adsorption-desorption curves of MOF-808 and MOF-808-Mn.

[0029] Figure 7 This is the nuclear magnetic resonance phosphorus spectrum of NEM and MOF-808-Mn after 5 minutes of exposure to glyphosate.

[0030] Figure 8 This is the nuclear magnetic resonance hydrogen spectrum of NEM and MOF-808-Mn after 5 minutes of action on glyphosate.

[0031] Fig. 9 This is a graph showing the degradation efficiency of MOF-808 and MOF-808-Mn for glyphosate over time. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1 Synthesis and characterization of materials

[0034] Preparation of MOF-808:

[0035] Zirconium chloride (720 mg, 3.09 mmol) and 1,3,5-benzenetricarboxylic acid (216 mg, 1.029 mmol) were added to a mixture of formic acid / water (FA / H2O volume ratio = 2.7:17.3) in a 50 mL round-bottom flask. Condensed and refluxed at 120°C for 24 h. Centrifuged and rinsed thoroughly with MeOH. Dry and activate at 120°C for 12 h to obtain MOF-808.

[0036] Preparation of MOF-808-Mn:

[0037] 100 mg of MOF-808 prepared in advance was dispersed in 40 mL of DMF containing 0.1 M Mn(NO3)2·4H2O, and the mixture was placed in a round-bottom flask. The mixture was heated to 85°C and maintained for 6 h under continuous stirring. The solid was then obtained by centrifugation (9500 × g, 3 min) and washed three times with DMF and acetone respectively. Finally, it was vacuum dried at 100°C to prepare MOF-808-Mn.

[0038]

[0039] Add 5 mg of the synthesized catalyst (MOF-808-Mn) and GP (8.75 mg, 50 μmol) to a 2 mL reaction bottle and stir for 5 min. After a certain reaction time, take out 0.5 mL of the reaction solution, filter it, and put it into a nuclear magnetic resonance tube for detection. 1 H. 31 P spectrum.

[0040] By scanning electron microscopy ( Figure 1 , Figure 2 ) and transmission electron microscopy ( Figure 3 ) confirmed the morphology and structure of the metal frame material.

[0041] like Figure 4 Shown are the X-ray diffraction patterns of MOF-808 and MOF-808-Mn; Figure 6 Shown are the adsorption-desorption curves of MOF-808 and MOF-808-Mn.

[0042] Example 2 Characterization of materials and analysis of GP degradation profile

[0043] like Figure 5 As shown, the synthetic material MOF-808-Mn also has the X-ray characteristic diffraction peaks of MOF-808 material, such as: 658cm -1 Zr-O, 1380cm -1 COO - 、1443cm -1 C=C、1568cm -1 C=C and 1619cm -1 COO - Etc. In addition, at 1029cm -1 The characteristic peak of Mn-OH appeared at 508 cm -1 and 2427cm -1 The characteristic peaks of Zr-O-Mn also appeared, indicating that Mn ions have been successfully doped into MOF-808 materials.

[0044] like Figure 7 As shown in the figure, when GP is treated with only MOF-808-Mn and without adding alkali, the characteristic peak of glyphosate disappears compared with the NMR phosphorus spectrum of glyphosate stock solution, indicating that GP can be completely degraded within 5 minutes. When only alkali is added, the phosphorus spectrum does not change.

[0045] like Figure 8 As shown, when GP was treated with only MOF-808-Mn and without adding alkali, a new characteristic peak appeared at 8.15 ppm compared with the H-NMR spectrum of glyphosate stock solution, indicating that glyphosate was converted into new substances and completely degraded.

[0046] like Fig. 9Shown is the degradation efficiency of MOF-808 and MOF-808-Mn on glyphosate over time.

[0047] The above specific implementation method part specifically introduces the analytical method involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the method and ideas of the present invention, rather than limiting the relevant content. Without departing from the principle of the present invention, those skilled in the art may also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications shall also fall within the scope of protection of the present invention.

Claims

1. A metal Mn-doped organic framework material for glyphosate degradation, characterized in that: Has the following structure:

2. The method for synthesizing a metal Mn-doped organic framework material for glyphosate degradation according to claim 1, characterized in that: MOF-808 was used as the metal framework material and Mn(NO3)2·4H2O was used as the doping metal for green synthesis.

3. The method for synthesizing a metal Mn-doped organic framework material for glyphosate degradation according to claim 2, characterized in that: The following steps are involved: (1) Preparation of MOF-808; (2) The pre-prepared MOF-808 is dispersed in DMF containing Mn(NO3)2·4H2O, and then the mixture is placed in a round-bottom flask; under continuous stirring, the reaction is carried out at a certain temperature for a period of time, and then a solid is obtained by centrifugation, and the solid is washed with DMF and acetone respectively, and finally vacuum dried to prepare the metal Mn-doped organic framework material.

4. The method for synthesizing a metal Mn-doped organic framework material for glyphosate degradation according to claim 3, characterized in that: In step (2), the ratio of MOF-808 to Mn(NO3)2·4H2O is 100 mg:4 mmol.

5. The method for synthesizing a metal Mn-doped organic framework material for glyphosate degradation according to claim 3, characterized in that: The reaction parameters in step (2) are: reaction at 85°C for 6 hours.

6. The method for synthesizing a metal Mn-doped organic framework material for glyphosate degradation according to claim 3, characterized in that: The specific steps of step (1) are as follows: zirconium chloride and 1,3,5-benzenetricarboxylic acid are added to a mixture of formic acid / water, placed in a round-bottom flask, condensed and refluxed at 120° C. for 24 hours, centrifuged, fully rinsed with MeOH, and dried and activated at 120° C. for 12 hours to obtain MOF-808.

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