Preparation method of zirconium-cobalt bimetallic phthalocyanine and application in degrading glyphosate in water body

Abstract

The present invention relates to the field of environmental protection and water pollution control, and discloses a preparation method of zirconium-cobalt bimetallic phthalocyanine and its application in degrading glyphosate in water bodies. Specifically, zirconium-cobalt bimetallic phthalocyanine catalyst is prepared by a solvothermal method using zirconium salt and cobalt phthalocyanine as raw materials and organic acid as a regulator. Its catalytic performance is regulated by optimizing the dosage of the regulator. The prepared catalyst can activate peroxymonosulfate, and the degradation rate of glyphosate in water bodies reaches 80% - 100%. The present invention discloses the preparation of a zirconium-cobalt bimetallic phthalocyanine catalyst and its application in the degradation of glyphosate in water bodies, which has broad application prospects in the field of water environmental protection.

Description

Technical Field

[0001] The present invention relates to a preparation method of zirconium-cobalt bimetallic phthalocyanine and its application in selectively degrading glyphosate in water bodies, belonging to the technical field of water pollution control. Background Art

[0002] With the rapid development of modern agriculture, glyphosate (N-(phosphonomethyl)glycine, PMG), as an efficient and broad-spectrum herbicide, has been widely used globally. The use of glyphosate has significantly increased crop yields and played an important role in alleviating the global food crisis. However, the long-term and large-scale application of glyphosate has caused serious environmental pollution problems. The residues of glyphosate in soil and water not only disrupt the ecological system balance, affect the diversity of soil microbial communities, but also may accumulate through the food chain, endangering public health and safety. Especially in the water environment, glyphosate shows high stability and strong toxicity to aquatic organisms. Therefore, it is urgent to develop efficient glyphosate degradation technologies to reduce its negative impact on the environment.

[0003] In the natural environment, glyphosate is mainly degraded through the following two pathways: (1) Under the catalytic action of glyphosate oxidoreductase, the C-N bond is broken to generate aminomethylphosphonic acid (AMPA), but the toxicity and environmental persistence of AMPA are both higher than those of glyphosate, further exacerbating the pollution problem; (2) Under the catalytic action of C-P lyase, the C-P bond is broken to generate non-toxic sarcosine and orthophosphate. However, under natural conditions, glyphosate is mainly degraded along the AMPA pathway, resulting in the accumulation of toxic intermediate products. Therefore, developing catalytic technologies that can efficiently degrade glyphosate and avoid the accumulation of AMPA is of great significance for ecological environmental protection and public health and safety.

[0004] Biocatalytic enzymes can achieve the selective degradation of glyphosate, but natural enzymes generally have defects such as poor operational stability, low environmental tolerance, and difficulty in reuse, which limit their practical applications. Artificial enzymes have become an important direction for the research on the selective degradation of glyphosate due to their strong controllability, high environmental stability, and good reusability. For example, Gan et al. constructed a biomimetic photocatalyst mCB-MOF-2 composed of Zr metal nodes and m-carborane carboxylate ligands based on the confined space characteristics of natural enzymes. This material has a high affinity for the phosphate end of glyphosate and realizes selective degradation under ultraviolet-visible light excitation, avoiding the generation of AMPA. However, this strategy is still limited by the insufficient specificity of the enzyme active center and further optimization of catalytic selectivity is required.

[0005] Designing nanozyme with both high activity and high selectivity for the safe degradation of glyphosate in water has important research value. Metal phthalocyanines widely exist in the active centers of natural enzymes, possess excellent catalytic properties, and show great potential in the construction of nanozymes. However, the low affinity of single-metal phthalocyanine for the phosphate group of glyphosate limits its selective degradation ability. Summary of the Invention

[0006] The present invention provides a method for the preparation of zirconium-cobalt bimetallic phthalocyanine and its application in catalyzing the degradation of organic pollutants in water. Based on the high selective adsorption ability of Zr6 cluster for the phosphate group of glyphosate, by optimizing the dosage of the regulator, the efficient and selective degradation of glyphosate is realized, providing a new solution for the development of environmentally friendly glyphosate degradation technology.

[0007] To achieve the above object, on the one hand, the present invention provides a method for the preparation of zirconium-cobalt bimetallic phthalocyanine, comprising the following steps:

[0008] Dissolve zirconium salt, organic acid and cobalt phthalocyanine in an organic solvent in proportion, and completely dissolve them under ultrasonic conditions to obtain a mixed solution. Transfer the mixed solution into a reaction kettle lined with polytetrafluoroethylene. After the reaction, wash with acetone, dry, grind to obtain zirconium-cobalt bimetallic phthalocyanine, and store it in a desiccator.

[0009] Preferably, the molar ratio of zirconium salt, cobalt phthalocyanine, and organic acid is 0.5-7.5:1:30-150.

[0010] The zirconium salt includes any one or a combination of zirconium chloride, zirconium acetate, zirconium nitrate, zirconium tetrafluoride, zirconium oxychloride, and zirconium carbonate.

[0011] The solvothermal reaction temperature is 130-160 °C, and the reaction time is 12-72 h.

[0012] The organic acid includes any one or a combination of salicylic acid, benzoic acid, and p-aminobenzoic acid.

[0013] The organic solvent includes N,N -dimethyl sulfoxide, N,N -dimethylformamide, N,N -diethylformamide, or any one or a combination of them.

[0014] On the second aspect, the present invention provides an application of zirconium-cobalt bimetallic phthalocyanine in activating peroxymonosulfate to degrade glyphosate in water. The zirconium-cobalt bimetallic phthalocyanine includes the catalyst prepared by the preparation method described in the first aspect of the present invention.

[0015] Mix cobalt bimetallic phthalocyanine with glyphosate wastewater, and then add peroxymonosulfate for the degradation reaction.

[0016] Preferably, the concentration range of the cobalt bimetallic phthalocyanine is 0.025 - 0.5 mg·L -1 。

[0017] Preferably, the concentration of glyphosate in the wastewater is 50 - 1000 μmol·L -1 。

[0018] Preferably, the concentration range of the peroxymonosulfate is 0.1 - 1.5 mmol·L -1 。

[0019] Preferably, the time of the degradation reaction is 60 - 180 min.

[0020] Advantages of the present invention:

[0021] In the present invention, a Zr / Co bimetallic synergistic catalytic system is constructed through metal doping. Through the electronic interaction between Zr and Co bimetals, the interfacial charge transfer is promoted, the activation efficiency of peroxymonosulfate and the degradation activity of glyphosate are improved; by optimizing the regulator, the electron cloud density of the organic framework is increased, the Lewis acidity of the Zr nodes is enhanced, and the formation of strong Zr–O–P coordination bonds between the phosphoric acid groups of glyphosate molecules and the Zr nodes is promoted, improving the selectivity of zirconium cobalt bimetallic phthalocyanine for catalyzing glyphosate degradation; by utilizing the synergistic stabilization effect of Zr nodes and Co–N4 coordination, the structural stability and reusability of the catalyst are effectively improved, and it has excellent catalytic performance and environmental application prospects. Description of the drawings

[0022] Figure 1 It is the SEM spectrum of the zirconium cobalt bimetallic phthalocyanine prepared in Example 1.

[0023] Figure 2 It is the TEM image and EDS analysis image of the zirconium cobalt bimetallic phthalocyanine prepared in Example 1. Among them, A is the TEM image and B is the EDS analysis image.

[0024] Figure 3 It is the XRD spectrum of the zirconium cobalt bimetallic phthalocyanine prepared in Example 1.

[0025] Figure 4 It is the XPS spectrum of the zirconium cobalt bimetallic phthalocyanine prepared in Example 1. Specific embodiments

[0026] The following combines specific examples to further illustrate the present invention, but the present invention is not limited to the following examples.

[0027] Example 1

[0028] Zirconium tetrachloride (0.84 g, 3.6 mmol), cobalt phthalocyanine (0.28 g, 0.5 mmol) and salicylic acid (3.47 g, 25.0 mmol) were dissolved in N,N N,N-dimethylformamide (56 mL), and ultrasonicated for 30 min to fully dissolve the solids, obtaining a mixed solution. The above mixed solution was transferred into a polytetrafluoroethylene reaction kettle and reacted at 140 °C for 72 h. After cooling to room temperature, it was centrifuged at 8000 rpm for 10 min using a high-speed centrifuge to separate the precipitate from the solution. The precipitate was washed three times with acetone, and the obtained precipitate was dried at 60 °C for 3 h and ground to obtain zirconium-cobalt bimetallic phthalocyanine.

[0029] As can be seen from Figure 1 , the prepared zirconium-cobalt bimetallic phthalocyanine exhibits a regular rod-like morphology, with a particle size range between 100 - 300 nm, and there is a certain roughness on the surface. Its porous micro-nano structure is beneficial to the adsorption of oxidants and pollutants and the improvement of catalytic activity. As can be seen from Figure 2 , the prepared zirconium-cobalt bimetallic phthalocyanine contains four elements, namely C, N, Co, and Zr, and is evenly distributed. As can be seen from Figure 3 , the main diffraction peaks of the prepared zirconium-cobalt bimetallic phthalocyanine are basically consistent with those of cobalt phthalocyanine (standard card 14 - 0948), and there are slight displacements in some peaks, indicating that the introduction of Zr 4+ causes a slight expansion of the lattice, and the zirconium doping does not destroy the framework structure of cobalt phthalocyanine. As can be seen from Figure 4 , the prepared zirconium-cobalt bimetallic phthalocyanine is composed of four elements, namely C, N, Co, and Zr. The above characterization results indicate that zirconium-cobalt bimetallic phthalocyanine has been successfully prepared, and its structure is uniform and the components are stable.

[0030] Example 2

[0031] In this example, the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1 was used. 3 mg of zirconium-cobalt bimetallic phthalocyanine was weighed and added to a glyphosate solution (40 mL, 300 μmol·L -1 ), and a persulfate solution (200 μL, 100 mmol·L -1 was added to initiate the degradation reaction. At 180 min of the reaction, 1 mL of the sample was taken, filtered through a 0.22 μm filter membrane, and Na2S2O8 (20 μL, 100 mmol·L -1 was added to terminate the reaction. Borax buffer solution (120 μL, 5%, pH 9.0) and 9-fluorenylmethyloxycarbonyl chloride (200 μL, 12.5 mg·mL -1 were added in sequence, and the derivatization reaction was carried out for 4 h. An aqueous HCl solution (15 μL, 6 mol·L -1)Terminate the reaction. After standing for 1 h, use a high-performance liquid chromatograph to detect the concentrations of glyphosate and AMPA in the solution. The degradation rate of glyphosate by the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1 activating peroxymonosulfate reached 82% in 3 h, and the concentration of the toxic intermediate product AMPA produced was 59 μmol·L -1 .

[0032] Example 3

[0033] Same as Example 1, the molar ratio of zirconium salt to organic acid is 1:15, and other methods remain unchanged. The prepared zirconium-cobalt bimetallic phthalocyanine is used to activate peroxymonosulfate to degrade the glyphosate solution by the method described in Example 2. The degradation rate of glyphosate is 94% in 180 min, and the concentration of AMPA produced is 41 μmol·L -1 .

[0034] Example 4

[0035] Same as Example 1, the molar ratio of zirconium salt to organic acid is 1:20, and other methods remain unchanged. The prepared zirconium-cobalt bimetallic phthalocyanine is used to activate peroxymonosulfate to degrade the glyphosate solution by the method described in Example 2. The degradation rate of glyphosate is 97% in 180 min, and the concentration of AMPA produced is 36 μmol·L -1 .

[0036] It can be seen that within a certain range, as the proportion of organic acid in the ratio of zirconium salt to organic acid increases, the degradation activity of the zirconium-cobalt bimetallic phthalocyanine activating peroxymonosulfate for glyphosate gradually increases, and the production amount of the toxic intermediate product AMPA gradually decreases under the condition of the same other conditions.

[0037] Example 5

[0038] Using the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1 as the catalyst, the method described in Example 2 is used to activate peroxymonosulfate to degrade the glyphosate solution. The degradation rate of glyphosate is 54% in 60 min; using the zirconium-cobalt bimetallic phthalocyanine prepared in Example 4 as the catalyst, the method described in Example 2 is used to activate peroxymonosulfate to degrade the glyphosate solution. The degradation rate of glyphosate is 81% in 60 min. It can be seen that when the molar ratio of zirconium salt to organic acid increases to 1:20, the degradation efficiency of the zirconium-cobalt bimetallic phthalocyanine for glyphosate can be significantly improved.

[0039] Example 6

[0040] Using the zirconium-cobalt bimetallic phthalocyanine prepared in Example 4, use NaOH (1 mol·L -1 ) to adjust the pH value of the glyphosate solution to neutral (pH 7.0), and use the method described in Example 2 to activate peroxymonosulfate to degrade the glyphosate solution. The degradation rate of glyphosate is 98% in 3 h, and the concentration of AMPA produced is 8 μmol·L-1 It shows that it can efficiently degrade glyphosate under neutral conditions while significantly inhibiting the generation of the toxic intermediate AMPA.

[0041] Example 7

[0042] The method described in Example 2 was used to determine the degradation activity of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 4 on glyphosate. After the first reaction, the catalyst was separated by centrifugation, washed three times successively with NaOH (1 mol·L -1 ), and secondary water, and then 40 mL of fresh glyphosate solution was added to initiate a new round of catalytic reaction. After cycling 5 times like this, its degradation activity on glyphosate still retained 93% of the initial activity. It can be seen that the prepared zirconium-cobalt bimetallic phthalocyanine has good stability.

[0043] Comparative Example 1

[0044] Using cobalt phthalocyanine as the catalyst, the method described in Example 2 was used to activate peroxymonosulfate to degrade the glyphosate solution. The degradation rate of glyphosate was 81% in 3 h, and the production amount of AMPA was 127 μmol·L -1 .

[0045] Comparative Example 2

[0046] Same as Example 4, the zirconium salt was replaced with a copper salt, and other methods remained unchanged. The prepared copper-cobalt bimetallic phthalocyanine activated peroxymonosulfate, and the degradation rate of glyphosate was 95% in 3 h, and the production amount of AMPA was 145 μmol·L -1 .

[0047] Comparative Example 3

[0048] Same as Example 4, the zirconium salt was replaced with an iron salt, and other methods remained unchanged. The prepared iron-cobalt bimetallic phthalocyanine activated peroxymonosulfate, and the degradation rate of glyphosate was 98% in 3 h, and the production amount of AMPA was 143 μmol·L -1 .

[0049] It can be seen that the introduction of the second metal can significantly improve the activity of the bimetallic phthalocyanine in activating peroxymonosulfate to degrade glyphosate, and only the introduction of metal zirconium can significantly reduce the generation of the toxic intermediate AMPA.

Claims

1. Application of zirconium-cobalt bimetallic phthalocyanine in activating monopersulfate to degrade glyphosate in water body, characterized in that, Mix zirconium-cobalt bimetallic phthalocyanine with glyphosate wastewater, and then add persulfate for degradation reaction. The preparation method of zirconium-cobalt bimetallic phthalocyanine comprises the following steps: After dissolving zirconium salt, cobalt phthalocyanine, and organic acid in an organic solvent, carry out a solvothermal reaction to obtain zirconium-cobalt bimetallic phthalocyanine. The molar ratio of zirconium salt, cobalt phthalocyanine, and organic acid is 0.5 - 7.5:1: 30 - 150.

2. The application according to claim 1, characterized in that, The concentration range of zirconium cobalt bimetallic phthalocyanine is 0.025 - 0.5 mg / L; the concentration range of peroxymonosulfate is 0.1 - 1.5 mmol·L -1 .

3. The application according to claim 1, wherein The concentration of glyphosate in the water body is 50 - 1000 μmol·L -1 .

4. The application according to claim 1, characterized in that, The time of the degradation reaction is 60 - 180 min.

5. The application according to claim 1, characterized in that The zirconium salt includes any one or a combination of zirconium chloride, zirconium acetate, zirconium nitrate, zirconium tetrafluoride, zirconium oxychloride, and zirconium carbonate.

6. The application according to claim 1, characterized in that, The organic acid includes any one or a combination of salicylic acid, benzoic acid, and p-aminobenzoic acid.

7. The application according to claim 1, characterized in that, The organic solvents described include N,N -dimethyl sulfoxide, N, N -dimethylformamide, N,N -diethylformamide, or any combination of one or more thereof.

8. The application according to claim 1, characterized in that, The solvothermal reaction temperature is 130 - 160 °C, and the reaction time is 12 - 72 h.

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