Preparation method of zirconium-cobalt bimetal phthalocyanine and application of zirconium-cobalt bimetal phthalocyanine in degradation of glyphosate in water body

Abstract

The invention relates to the field of environmental protection and water pollution control, and discloses a preparation method of zirconium-cobalt bimetal phthalocyanine and application of zirconium-cobalt bimetal phthalocyanine to degradation of glyphosate in a water body. The invention specifically discloses a zirconium-cobalt bimetallic phthalocyanine catalyst prepared by taking zirconium salt and cobalt phthalocyanine as raw materials and organic acid as a regulator and adopting a solvothermal method. The catalytic performance of the catalyst is regulated and controlled by optimizing the dosage of the regulator. The prepared catalyst can activate peroxymonosulfate, and the degradation rate of glyphosate in a water body reaches 80%-100%. The invention discloses preparation of a zirconium-cobalt bimetallic phthalocyanine catalyst and application of the zirconium-cobalt bimetallic phthalocyanine catalyst in degradation of glyphosate in a water body. The zirconium-cobalt bimetallic phthalocyanine catalyst has a wide application prospect in the field of water environment protection.

Description

Technical Field

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

[0002] With the rapid development of modern agriculture, glyphosate (N-(phosphonomethyl)glycine, PMG) has been widely used worldwide as an efficient and broad-spectrum herbicide. 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 destroy the balance of the ecosystem and affect the diversity of soil microbial communities, but may also accumulate through the food chain and endanger public health and safety. Especially in the aquatic environment, glyphosate shows high stability and is highly toxic to aquatic organisms. Therefore, it is urgent to develop efficient glyphosate degradation technology to reduce its negative impact on the environment.

[0003] In the natural environment, glyphosate is degraded mainly through the following two pathways: (1) Under the catalytic action of glyphosate oxidoreductase, the CN bond breaks to generate aminomethylphosphonic acid (AMPA), but the toxicity and environmental persistence of AMPA are higher than glyphosate, further aggravating the pollution problem; (2) Under the catalytic action of CP lyase, the CP bond breaks 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 intermediates. Therefore, the development of catalytic technology 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] Bioenzyme catalysis 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 limits their practical application. Due to its strong controllability, high environmental stability, and good reusability, mimetic enzymes have become an important direction for the selective degradation of glyphosate. For example, Gan et al. constructed a biomimetic photocatalyst mCB-MOF-2 composed of Zr metal nodes and meta-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 achieves selective degradation under ultraviolet-visible light excitation, avoiding the formation of AMPA. However, this strategy is still limited by the lack of specificity of the enzyme active center, and the catalytic selectivity needs to be further optimized.

[0005] Designing nano-mimetic enzymes with both high activity and high selectivity for safe degradation of glyphosate in water bodies is of great research value. Metal phthalocyanines are widely present in the active centers of natural enzymes, have excellent catalytic properties, and show great potential in the construction of mimetic enzymes. However, single metal phthalocyanines have a low affinity for the phosphate end of glyphosate, which limits their selective degradation ability. Summary of the invention

[0006] The present invention provides a method for preparing zirconium-cobalt bimetallic phthalocyanine and catalyzing the degradation of organic pollutants in water. 6 The cluster has a high selective adsorption capacity for the phosphate end of glyphosate, and by optimizing the dosage of the regulator, it can achieve efficient and selective degradation of glyphosate, providing a new solution for the development of environmentally friendly glyphosate degradation technology.

[0007] In order to achieve the above object, the present invention provides a method for preparing zirconium-cobalt bimetallic phthalocyanine, comprising the following steps: 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 polytetrafluoroethylene-lined reactor, and after the reaction is completed, wash with acetone, dry, grind to obtain zirconium-cobalt bimetallic phthalocyanine, and store it in a desiccator.

[0008] Preferably, the molar ratio of zirconium salt, cobalt phthalocyanine and organic acid is 0.5-7.5:1:30-150.

[0009] The zirconium salt includes any one or more combinations of zirconium chloride, zirconium acetate, zirconium nitrate, zirconium tetrafluoride, zirconium oxychloride and zirconium carbonate.

[0010] The solvent thermal reaction temperature is 130~160℃, and the reaction time is 12~72 h.

[0011] The organic acid includes any one or more combinations of salicylic acid, benzoic acid and p-aminobenzoic acid.

[0012] The organic solvent includes N,N -dimethyl sulfoxide, N,N -dimethylformamide, N,N -Any one or more combinations of diethylformamide.

[0013] The second aspect of the present invention provides an application of zirconium-cobalt bimetallic phthalocyanine to activate peroxymonosulfate to degrade glyphosate in water. The zirconium-cobalt bimetallic phthalocyanine comprises a catalyst prepared by the preparation method described in the first aspect of the present invention.

[0014] Cobalt bimetallic phthalocyanine is mixed with glyphosate wastewater, and then peroxymonosulfate is added to carry out degradation reaction.

[0015] Preferably, the concentration of the cobalt bimetallic phthalocyanine is in the range of 0.025 to 0.5 mg·L -1 .

[0016] Preferably, the concentration of glyphosate in the wastewater is 50 to 1000 μmol·L -1 .

[0017] Preferably, the concentration of the peroxymonosulfate is in the range of 0.1 to 1.5 mmol·L -1 .

[0018] Preferably, the degradation reaction time is 60 to 180 min.

[0019] Advantages of the present invention: The invention constructs a Zr / Co bimetallic synergistic catalytic system by metal doping, promotes interfacial charge transfer through electronic interaction between Zr and Co bimetallics, and improves the activation efficiency of peroxymonosulfate and the degradation activity of glyphosate; improves the electron cloud density of the organic skeleton by optimizing the regulator, enhances the Lewis acidity of the Zr node, promotes the formation of a strong Zr-O-P coordination bond between the phosphate group of the glyphosate molecule and the Zr node, and improves the selectivity of the degradation of glyphosate by the zirconium-cobalt bimetallic phthalocyanine; utilizes the Zr node and the Co-N 4 The synergistic stabilizing effect of coordination effectively improves the structural stability and reusability of the catalyst, and it has excellent catalytic performance and environmental application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the SEM spectrum of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1.

[0021] Figure 2 These are the TEM image and EDS analysis image of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1, wherein A is the TEM image and B is the EDS analysis image.

[0022] Figure 3 This is the XRD spectrum of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1.

[0023] Figure 4 This is the XPS spectrum of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0025] Example 1 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 -dimethylformamide (56 mL), ultrasonic for 30 min to fully dissolve the solid to obtain a mixed solution. The mixed solution was transferred to a polytetrafluoroethylene reactor, reacted at 140°C for 72 h, cooled to room temperature, centrifuged at 8000 rpm for 10 to separate the precipitate from the solution, 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.

[0026] from Figure 1 It can be seen that the prepared zirconium-cobalt bimetallic phthalocyanine has a regular rod-like morphology, a particle size range of 100-300nm, a certain degree of surface roughness, and its porous micro-nano structure is conducive to the adsorption of oxidants and pollutants and the improvement of catalytic activity. Figure 2 It can be seen that the prepared zirconium-cobalt bimetallic phthalocyanine contains four elements, C, N, Co, and Zr, and they are evenly distributed. Figure 3 It can be seen that the main diffraction peaks of the prepared zirconium-cobalt bimetallic phthalocyanine and cobalt phthalocyanine (standard card 14-0948) are basically consistent, and some peaks have slight shifts, indicating that Zr 4+ The introduction of zirconium leads to a slight expansion of the lattice, and zirconium doping does not destroy the framework structure of cobalt phthalocyanine. Figure 4 It can be seen that the prepared zirconium-cobalt bimetallic phthalocyanine is composed of four elements: C, N, Co, and Zr. The above characterization results show that the zirconium-cobalt bimetallic phthalocyanine was successfully prepared, and the structure was uniform and the components were stable.

[0027] Example 2 In this example, the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1 was used. Zirconium-cobalt bimetallic phthalocyanine (3 mg) was weighed and a glyphosate solution (40 mL, 300 μmol·L -1 ), add peroxymonosulfate solution (200 μL, 100 mmol·L -1 ) to start the degradation reaction. After 180 min of reaction, 1 mL of sample was taken and filtered through a 0.22 μm filter membrane. Na 2 S 2 O 8 (20 μL, 100mmol·L -1 ) to terminate the reaction. Borax buffer (120 μL, 5%, pH 9.0) and 9-Fluorenylmethoxycarbonyl chloride (200 μL, 12.5 mg mL -1 ), derivatization reaction for 4 h, and then adding HCl aqueous solution (15 μL, 6 mol·L -1) to terminate the reaction, and after standing for 1 h, the concentrations of glyphosate and AMPA in the solution were detected by high performance liquid chromatography. The degradation rate of glyphosate by the zirconium-cobalt bimetallic phthalocyanine activated peroxymonosulfate prepared in Example 1 reached 82% in 3 h, and the concentration of the toxic intermediate AMPA produced was 59 μmol·L -1 .

[0028] Example 3 The same as in Example 1, except that the molar ratio of zirconium salt to organic acid was 1:15, and other methods were unchanged. The prepared zirconium-cobalt bimetallic phthalocyanine was activated with persulfate by the method described in Example 2 to degrade glyphosate solution. The degradation rate of glyphosate was 94% in 180 min, and the concentration of AMPA produced was 41 μmol·L -1 .

[0029] Example 4 The same as in Example 1, except that the molar ratio of zirconium salt to organic acid was 1:20, and other methods remained unchanged. The prepared zirconium-cobalt bimetallic phthalocyanine was activated with persulfate by the method described in Example 2 to degrade glyphosate solution. The degradation rate of glyphosate was 97% in 180 min, and the concentration of AMPA produced was 36 μmol·L -1 .

[0030] 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 zirconium-cobalt bimetallic phthalocyanine activated permonosulfate for glyphosate prepared under the same other conditions gradually increases, and the production of the toxic intermediate AMPA gradually decreases.

[0031] Example 5 Using the zirconium-cobalt bimetallic phthalocyanine prepared in Example 1 as a catalyst, the method described in Example 2 was used to activate permonosulfate to degrade glyphosate solution, and the degradation rate of glyphosate was 54% in 60 min; using the zirconium-cobalt bimetallic phthalocyanine prepared in Example 4 as a catalyst, the method described in Example 2 was used to activate permonosulfate to degrade glyphosate solution, and the degradation rate of glyphosate was 81% in 60 min. It can be seen that when the molar ratio of zirconium salt to organic acid is increased to 1:20, the degradation efficiency of zirconium-cobalt bimetallic phthalocyanine for glyphosate can be significantly improved.

[0032] Example 6 The zirconium-cobalt bimetallic phthalocyanine prepared in Example 4 was quenched with NaOH (1 mol·L -1 ) The pH value of the glyphosate solution was adjusted to neutral (pH 7.0), and the persulfate was activated to degrade the glyphosate solution using the method described in Example 2. The degradation rate of glyphosate was 98% within 3 h, and the concentration of AMPA produced was 8 μmol·L -1 This indicates that it can efficiently degrade glyphosate under neutral conditions and significantly inhibit the production of the toxic intermediate AMPA.

[0033] Example 7 The degradation activity of the zirconium-cobalt bimetallic phthalocyanine prepared in Example 4 on glyphosate was determined by the method described in Example 2. After the first reaction, the catalyst was separated by centrifugation and then treated with NaOH (1 mol·L -1 ) and secondary water for three times, and then 40 mL of fresh glyphosate solution was added to start a new round of catalytic reaction. After five cycles, its degradation activity for glyphosate still retained 93% of the initial activity. It can be seen that the prepared zirconium-cobalt bimetallic phthalocyanine has good stability.

[0034] Comparative Example 1 Using cobalt phthalocyanine as a catalyst, the method described in Example 2 was used to activate persulfate to degrade glyphosate solution. The degradation rate of glyphosate was 81% within 3 h, and the amount of AMPA produced was 127 μmol·L -1 .

[0035] Comparative Example 2 The same method as in Example 4 was used to replace zirconium salt with copper salt. The other methods remained unchanged. The degradation rate of glyphosate by the prepared copper-cobalt bimetallic phthalocyanine activated peroxymonosulfate was 95% within 3 h, and the production of AMPA was 145 μmol·L -1 .

[0036] Comparative Example 3 The same method as in Example 4 was used to replace the zirconium salt with the iron salt. The other methods remained unchanged. The degradation rate of glyphosate by the prepared iron-cobalt bimetallic phthalocyanine activated persulfate was 98% in 3 h, and the production amount of AMPA was 143 μmol·L -1 .

[0037] It can be seen that the introduction of the second metal can significantly enhance the activity of bimetallic phthalocyanine in activating persulfate to degrade glyphosate, and only the introduction of metal zirconium can significantly reduce the production of the toxic intermediate AMPA.

Claims

1. A method for preparing zirconium-cobalt bimetallic phthalocyanine, characterized in that: The steps include: After dissolving zirconium salt, cobalt phthalocyanine and organic acid in an organic solvent, a solvothermal reaction is carried out to obtain zirconium-cobalt bimetallic phthalocyanine.

2. The method for preparing zirconium-cobalt bimetallic phthalocyanine according to claim 1, characterized in that: The zirconium salt includes any one or more combinations of zirconium chloride, zirconium acetate, zirconium nitrate, zirconium tetrafluoride, zirconium oxychloride and zirconium carbonate.

3. The method for preparing zirconium-cobalt bimetallic phthalocyanine according to claim 1, characterized in that: The organic acid includes any one or more combinations of salicylic acid, benzoic acid and p-aminobenzoic acid.

4. The method for preparing zirconium-cobalt bimetallic phthalocyanine according to claim 1, characterized in that: The organic solvent includes N,N -dimethyl sulfoxide, N,N -dimethylformamide, N,N -Any one or more combinations of diethylformamide.

5. The method for preparing zirconium-cobalt bimetallic phthalocyanine according to claim 1, characterized in that: The molar ratio of zirconium salt, cobalt phthalocyanine and organic acid is 0.5 ~ 7.5:1: 30-150.

6. The method for preparing zirconium-cobalt bimetallic phthalocyanine according to claim 1, characterized in that: The solvent thermal reaction temperature is 130-160°C and the reaction time is 12 to 72 h.

7. Use of zirconium-cobalt bimetallic phthalocyanine prepared by the method according to any one of claims 1 to 6 to activate persulfate to degrade glyphosate in water.

8. The use according to claim 7, 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 .

9. The use according to claim 7, characterized in that: The concentration of glyphosate in water is 50 ~ 1000 μmol·L -1 .

10. The use according to claim 7, characterized in that The degradation reaction time is 60~180 min.

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