Metal mn-doped organic framework material for glyphosate degradation and synthesis method thereof

Abstract

The application discloses a metal Mn-doped organic framework material for glyphosate degradation and a synthesis method thereof, and belongs to the technical field of metal organic framework materials. The synthesis method adopts MOF-808 as a metal framework material and adopts Mn(NO3)2.4H2O as a doped metal to realize green synthesis. The prepared material has the advantages of fast response time, high selectivity and high degradation rate. After the metal framework material reacts with GP, the P=O double bond in the structure of the organophosphorus pesticide glyphosate is broken, the macromolecular toxic substance is converted into a small-molecule non-toxic substance, and great potential is achieved in the aspect of environmental protection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal organic framework materials, and particularly relates to a metal Mn-doped organic framework material for glyphosate degradation and a synthesis method thereof. BACKGROUND

[0002] Glyphosate (GP) is widely used for weed control due to its excellent herbicidal performance. 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 leads to an increasing residue of glyphosate in soil and drinking water, which poses 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 carcinogenic and genotoxic effects on humans, and can damage the immune and endocrine systems. In addition, the toxicity of the main degradation intermediate of glyphosate (including natural degradation and advanced oxidation process), aminomethyl phosphonic acid (AMPA), has also been found to be higher than that of glyphosate. More and more studies have shown that GP and AMPA can cause chromosomal aberrations in fish and carcinogenesis in human red blood cells. As a new type of pollutant, the content of glyphosate in the environment and its degradation process in wastewater treatment have attracted widespread attention. Therefore, it is crucial to establish a convenient and rapid method for degrading GP while avoiding the generation of toxic by-products.

[0003] With the development of detection technology, the current methods for degrading GP are increasingly diversified. Mainly include plant absorption method, chemical degradation method, microbial degradation method and biodegradable product method, etc. The plant absorption method is to use 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 rapidly reduce the content of glyphosate in 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 microbial degradation agents. This method utilizes the natural degradation ability of microorganisms and does not cause additional pollution to the environment. However, the microbial degradation of glyphosate requires a long time, and the effect of microbial degradation may be affected by various factors such as soil conditions, temperature, humidity, etc., resulting in unstable effect. In addition, various metal materials can also be used to degrade glyphosate.

[0004] Metal-organic framework materials (MOFs) are increasingly favored by researchers due to their excellent performance and application prospects in adsorption, separation, catalysis and other aspects. Due to the presence of strong Lewis metal ions in the metal nodes of MOFs, it is excellent in activating coordinated organophosphorus and decomposing the phosphate ester bonds of these organophosphorus. Therefore, the present application provides a material based on metal Mn doped green synthesis of MOF-808 for degrading glyphosate. SUMMARY

[0005] The purpose of the present application 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, it will cause the structure of GP to break, so that it is converted from a large molecule toxic compound to a small molecule non-toxic compound, thereby achieving the purpose of degrading GP. At the same time, the metal composite material has rapid response and high sensitivity in degrading GP, and has very superior degradation capacity.

[0006] The purpose of the present application can be achieved by 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 uses MOF-808 as the metal framework material and Mn(NO3)2·4H2O as the doped metal for green synthesis. Specifically, it includes the following steps:

[0010] (1) preparing MOF-808;

[0011] (2) dispersing the previously prepared MOF-808 in N,N-dimethylformamide (DMF) containing Mn(NO3)2·4H2O, then placing the mixture in a round-bottom flask; under continuous stirring, reacting at a certain temperature for a period of time, then obtaining the solid by centrifugation (9500xg, 3min), and washing with DMF and acetone for three times respectively; finally, vacuum drying at 100℃, thereby preparing MOF-808-Mn (i.e. the metal Mn doped organic framework material).

[0012] Further, the specific steps of step (1) are as follows: adding zirconium chloride and 1,3,5-benzene tricarboxylic acid to a mixture of formic acid / water, placing it in a round-bottom flask, condensing and refluxing at 120℃ for 24h, centrifuging, washing thoroughly with MeOH, and drying and activating at a temperature of 120℃ for 12h to obtain MOF-808.

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

[0014] Further, the reaction parameters in step (2) are: 85℃ temperature condition for 6h.

[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 adding alkali.

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

[0019] The beneficial effects of the present application are:

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

[0021] (2) The metal composite material provided by the present application is simple to synthesize, and only needs to go through two steps to complete the synthesis. BRIEF DESCRIPTION OF DRAWINGS

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

[0023] Figure 1 is a scanning electron microscope spectrum of MOF-808.

[0024] Figure 2 is a scanning electron microscope spectrum of MOF-808-Mn.

[0025] Figure 3 is a transmission electron microscope spectrum of MOF-808-Mn.

[0026] Figure 4 is an X-ray diffraction spectrum of MOF-808 and MOF-808-Mn.

[0027] Figure 5 is an infrared spectrum of MOF-808 and MOF-808-Mn.

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

[0029] Figure 7 are the nuclear magnetic resonance phosphorus spectra of NEM and MOF-808-Mn on glyphosate for 5 min.

[0030] Figure 8 are the nuclear magnetic resonance hydrogen spectra of NEM and MOF-808-Mn on glyphosate for 5 min.

[0031] Figure 9 are the degradation efficiency graphs of MOF-808 and MOF-808-Mn on glyphosate over time. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0033] Synthesis and characterization of materials in Example 1

[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. Condensation reflux was carried out at 120 °C for 24 h. Centrifugation was performed, and the product was washed thoroughly with MeOH. Drying of the activated product was carried out at 120 °C for 12 h to obtain MOF-808.

[0036] Preparation of MOF-808-Mn:

[0037] Prepared 100 mg of MOF-808 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 for 6 h under continuous stirring. The solid was obtained by centrifugation (9500 x g, 3 min) and washed with DMF and acetone three times, respectively. Finally, MOF-808-Mn was prepared by vacuum drying at 100 °C.

[0038]

[0039] Synthesized catalyst (MOF-808-Mn) 5mg and GP (8.75mg, 50μmol) were added into 2mL reaction bottle, stirred for 5min. 0.5mL reaction solution was taken out after a certain time, filtered, and loaded into NMR tube to detect its 1 H, 31 P spectrum.

[0040] The morphology and structure of the metal framework material were confirmed by scanning electron microscopy ( Figure 1 、 Figure 2 ) and transmission electron microscopy ( Figure 3 ).

[0041] As shown in Figure 4 , the X-ray diffraction patterns of MOF-808 and MOF-808-Mn; as shown in Figure 6 , the adsorption and desorption curves of MOF-808 and MOF-808-Mn.

[0042] Characterization of Example 2 material and analysis of GP degradation spectrum

[0043] As shown in Figure 5 , the synthesized 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, the characteristic peak of Mn-OH appears at 1029cm -1 , and the characteristic peak of Zr-O-Mn also appears at 508cm -1 and 2427cm -1 , indicating that Mn ions have been successfully doped into the MOF-808 material.

[0044] As shown in Figure 7 , compared with the NMR spectrum of glyphosate stock solution, the characteristic peak of glyphosate disappeared under the condition of only MOF-808-Mn without adding base, indicating that GP can be completely degraded in 5min. In the case of only base, the phosphorus spectrum does not change.

[0045] As shown in Figure 8 , compared with the NMR spectrum of glyphosate stock solution, a new characteristic peak appears at 8.15ppm under the condition of only MOF-808-Mn without adding base, indicating that glyphosate is converted into a new substance and is completely degraded.

[0046] As shown in Figure 9Shown is a plot of glyphosate degradation efficiency over time for MOF-808 and MOF-808-Mn.

[0047] The above detailed description of the analysis method to which the present application relates. It should be noted that the above description is only to help those skilled in the art better understand the method and ideas of the present application, and is not a limitation on the relevant content. Those skilled in the art can also make appropriate adjustments or modifications to the present application without departing from the principles of the present application, and the above adjustments and modifications should also be within the scope of protection of the present application.

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 is used as a metal framework material, and Mn(NO3)2.4H2O is used as a doped 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 method comprises the following steps: (1) preparing MOF-808; (2) dispersing the prepared MOF-808 in DMF containing Mn(NO3)2.4H2O, then placing the mixture in a round-bottom flask; under continuous stirring, reacting for a period of time under a certain temperature condition, then obtaining the solid by centrifugation, and washing with DMF and acetone respectively, and finally vacuum drying, thereby preparing 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 the amount 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, In step (2), the reaction parameters are: 85℃ temperature condition for 6h.

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, and condensed and refluxed at 120℃ for 24h, centrifuged, fully rinsed with MeOH, and dried and activated at a temperature of 120℃ for 12h to obtain MOF-808.

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