A citric acid-modified copper peroxide nanozyme and its preparation method and use

Abstract

This invention provides a citric acid-modified copper peroxide nanozyme, its preparation method, and uses, relating to the field of nanomaterials. By selecting suitable preparation conditions, nanozymes with particle sizes ranging from 1 to 120 nm can be obtained. This novel copper-based Fenton-like nanozyme achieves self-supply of H₂O₂, driving a Fenton-like reaction to produce ·OH. It can efficiently degrade organic pollutants such as pesticides in water and soil over a wide pH range, enabling in situ remediation of water and soil environments.

Description

Technical Field

[0001] The technical solution of the present invention relates to the field of nanomaterials, and in particular to a citric acid-modified copper peroxide nanozyme and a preparation method and use thereof. Background Art

[0002] Chemical pesticides play an indelible role in addressing pest and disease problems in current agricultural production and ensuring global food security. However, with the continued use of pesticides, a variety of long-lasting pesticide residues have been detected in field soils. These residues affect soil enzyme activity and microbial communities, severely impacting the yield and quality of agricultural products and posing a significant threat to human health. Some pesticide residues can also be transferred to various environmental water bodies through leaching and runoff, damaging the DNA of some aquatic organisms. Therefore, the development of efficient in situ remediation methods is crucial for eliminating pesticide residues in soil and water.

[0003] Advanced oxidation processes (AOPs) have shown great potential in treating various emerging pollutants. Under reaction conditions such as high temperature and high pressure, electricity, sound, light radiation, and catalysts, highly active free radicals with strong oxidizing ability are generated. These free radicals can oxidize many complex organic substances, directly mineralize them, or improve the biodegradability of pollutants through oxidation, ultimately oxidizing large-molecule, difficult-to-degrade organic matter into low-toxic or non-toxic small-molecule substances.

[0004] Nanozymes are a class of nanoparticles with enzyme-like catalytic activity. Their small size and high surface area significantly increase the number of reaction sites with pollutants. Compared to conventionally sized materials, nanozymes can penetrate tiny underground cracks, exhibiting higher mobility. They can better disperse into pollution source areas (aquifers and soils) and remain suspended for extended periods during water remediation. Therefore, using engineered nanozymes for in situ remediation of organic pollutants is an effective approach. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a citric acid-modified copper peroxide nanozyme and its preparation method and use. The present invention provides a novel citric acid-modified copper peroxide nanozyme with excellent peroxidase activity, which can achieve self-supply of H2O2, drive a Fenton-like reaction to produce ·OH, and have a good degradation effect on organic pollutants such as pesticides.

[0006] The present invention provides a citric acid-modified copper peroxide nanozyme for in situ remediation of organic pollutants such as pesticides in the environment. The nanozyme is characterized in that, compared with the existing technology, the nanozyme does not require additional energy consumption such as high temperature, high pressure, electricity, sound, and light, has a wide pH requirement, and can achieve in situ remediation of herbicide pollution under natural conditions with few side effects.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a citric acid-modified copper peroxide nanozyme and a preparation method thereof, comprising:

[0009] Polyvinyl pyrrolidone is dissolved in a copper salt solution, and an alkaline solution and hydrogen peroxide are added to the mixed solution in sequence. An oxidation-reduction reaction is carried out under magnetic stirring conditions, and nano-copper peroxide is obtained by centrifugation. The obtained nano-copper peroxide is dispersed in a citric acid-anhydrous ethanol solution and surface modified under magnetic stirring conditions to obtain citric acid-modified copper peroxide nanozyme.

[0010] Preferably, the solvent of the copper salt solution and the alkali solution is 0-100% ethanol aqueous solution.

[0011] Preferably, the average molecular weight of the polyvinyl pyrrolidone is 8,000, 10,000, 24,000, 40,000, or 58,000, and the concentration thereof is 1-10%.

[0012] Preferably, the copper salt is copper sulfate, copper chloride, or copper nitrate, and the concentration of the solution is 1 to 100 mM.

[0013] Preferably, the base is sodium hydroxide, potassium hydroxide, or ammonia water, and the concentration of the solution is 1 to 200 mM.

[0014] Preferably, the molar ratio of the copper salt to the base is 1:1 to 1:10.

[0015] Preferably, the final concentration of the hydrogen peroxide is 0.1-1%.

[0016] Preferably, the citric acid-anhydrous ethanol solution has a citric acid concentration of 1 to 500 mM, more preferably 10 to 100 mM.

[0017] Preferably, the redox reaction time is 5 to 120 minutes, and the citric acid modification reaction time is 5 to 600 minutes.

[0018] The nano copper peroxide prepared by the above technical solution provided by the present invention has a particle size of 1 to 100 nm, and the particle size of the citric acid-modified copper peroxide nanozyme is 1 to 120 nm.

[0019] The present invention provides the use of citric acid-modified copper peroxide nanozymes prepared by the above technical solution in the remediation of organic pollutants such as pesticides in the environment.

[0020] Preferably, the concentration of the citric acid-modified copper peroxide nanozyme used in soil environmental remediation is 0.001-0.1%, more preferably 0.005-0.05%.

[0021] Preferably, the concentration of the citric acid-modified copper peroxide nanozyme used in water environment remediation is 0.001-0.05%, more preferably 0.005-0.02%.

[0022] Preferably, the organic pollutants such as pesticides include: nicosulfuron-methyl, bensulfuron-methyl, sulfasulfuron-methyl, pyrazosulfuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, tribenuron-methyl, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the HR-TEM image of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0024] Figure 2 This is the XRD pattern of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0025] Figure 3 This is the XPS graph of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0026] Figure 4 This is the infrared spectrum of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0027] Figure 5 The free radical generated by ESR analysis of the citric acid-modified copper peroxide nanozyme prepared in Example 1 is ·OH.

[0028] Figure 6 The citric acid-modified copper peroxide nanozyme prepared in Example 1 oxidized ABTS to green oxABTS with a maximum absorption at 734 nm.

[0029] Figure 7 The degradation rate changes of different concentrations of nicosulfuron in water catalyzed by nanozymes in Example 2.

[0030] Figure 8 The initial concentration of nicosulfuron in the water body catalyzed by nanozyme in Example 2 was 10 μg·mL -1 HPLC spectra of the reaction system at 0, 1, 2, and 4 h.

[0031] Figure 9 This is the degradation effect of the nanozyme catalyzing the degradation of 7 sulfonylurea herbicides in water in Example 3.

[0032] Figure 10This potted experiment, using wheat as the indicator plant, evaluated the remediation effect of nanozymes on nicosulfuron residues in soil, as described in Example 4. Substrates I-IV were, in order, blank soil control, soil remediated by citric acid-modified copper peroxide nanozyme, soil remediated by nanocopper peroxide, and unremediated soil containing the drug.

[0033] Figure 11 The copper peroxide nanozyme modified by citric acid is in a flaky shape with a particle size of about 50 nm prepared in Example 5. DETAILED DESCRIPTION

[0034] The present invention is further described with reference to the following examples.

[0035] Example 1

[0036] Preparation method of citric acid-modified copper peroxide nanozyme

[0037] The specific operation is as follows: 1g polyvinylpyrrolidone (molecular weight 10000) is dissolved in 10mL of 90% ethanol aqueous solution containing CuSO4·5H2O (10mM), and 10mL of NaOH (20mM) 90% ethanol aqueous solution and 200μL of 30% H2O2 are added in sequence under magnetic stirring conditions, magnetic stirring is carried out for 20min, and the precipitate is collected by ultracentrifugation to obtain nano-copper peroxide; the obtained nano-copper peroxide is ultrasonically dispersed in 20mL of 50mM citric acid-anhydrous ethanol solution, and surface modification is carried out under magnetic stirring for 4h. The precipitate is collected by centrifugation again, and it is re-dispersed and centrifuged and washed several times with anhydrous ethanol. The precipitate is placed in vacuum drying for 12h to obtain a dot-shaped citric acid-modified copper peroxide nanozyme with a particle size of about 2.3nm.

[0038] Figure 1 This is the HR-TEM image of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0039] Figure 2 This is the XRD pattern of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0040] Figure 3 This is the XPS graph of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0041] Figure 4 This is the infrared spectrum of the citric acid-modified copper peroxide nanozyme prepared in Example 1.

[0042] Figure 5 The free radical generated by ESR analysis of the citric acid-modified copper peroxide nanozyme prepared in Example 1 is ·OH.

[0043] Figure 6The citric acid-modified copper peroxide nanozyme prepared in Example 1 oxidized ABTS to oxABTS and had a maximum absorption at 734 nm.

[0044] Example 2

[0045] The citric acid-modified copper peroxide nanozyme prepared in Example 1 was used as a catalyst to degrade nicosulfuron herbicide residues in water.

[0046] Three different concentrations of nicosulfuron aqueous solution (5 μg·mL -1 , 10 μg·mL -1 , 20 μg·mL -1 ), accurately weigh 0.01g of the citric acid-modified copper peroxide nanozyme prepared in Example 1, and add them to 100mL of the above-mentioned nicosulfuron aqueous solution of different concentrations to time the reaction, and repeat three times for each concentration. HPLC (Agilent HPLC-1260 series) was used to detect the residual concentration of nicosulfuron in the reaction system, and all samples were filtered through a 0.22μm filter membrane and then subjected to HPLC detection. The separation column used was WondaSil C18 Superb (4.6mm×250mm×5μm), the injection volume was 10μL, the mobile phase was acetonitrile: 0.1% glacial acetic acid aqueous solution = 40:60, the detection wavelength was 240nm, and the retention time was 8min. The degradation rate calculation formula is: conversion rate (%) = [(control group concentration-treatment group concentration) / control group concentration] × 100. The results are as follows Figure 7 As shown in the figure, the degradation rates reached 97.58%, 92.32% and 72.23% in 56 min, respectively.

[0047] Figure 8 The initial concentration of nicosulfuron was 10 μg·mL -1 HPLC spectra of the reaction system at 0, 1, 2, and 4 h. It was completely degraded at 4 h and could not be detected.

[0048] Example 3

[0049] The citric acid-modified copper peroxide nanozyme prepared in Example 1 was used as a catalyst to degrade the herbicide residues of sulfamethoxam, sulfamethoxam, bensulfuron-methyl, pyrazosulfuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, and bensulfuron-methyl in water. Considering the different solubility of each herbicide in water, the concentration of sulfamethoxam was 5 μg·mL -1 The concentrations of the other six herbicides were all 10 μg·mL -1 The catalyst addition concentration was 0.1 mg·mL -1 The residual concentration of nicosulfuron in the reaction system was detected by HPLC (Agilent HPLC-1260 series). The detection conditions are shown in Table 1. Figure 9As shown in the data, in the water reaction system, the catalyst had the highest degradation activity for sulfamethoxam, with the degradation rate of sulfamethoxam reaching 96.25% at 24 min; followed by sulfamethoxam, with the degradation rate of sulfamethoxam reaching 96.20% at 48 min; and the degradation rates of benzylsulfuron-methyl, pyrazosulfuron-methyl, thifensulfuron-methyl, metsulfuron-methyl and tribenuron-methyl were 96.45%, 94.02%, 51.99%, 22.17% and 18.16% respectively at 56 min.

[0050] Table 1 HPLC detection conditions for seven sulfonylurea herbicides

[0051]

[0052] Example 4

[0053] The citric acid-modified copper peroxide nanozyme prepared in Example 1 was used as a catalyst and wheat was used as an indicator plant to evaluate the degradation effect of the nanozyme on nicosulfuron in the soil.

[0054] The wheat variety is Shixin 828. The concentration of nicosulfuron added to the soil is 0.1 mg kg -1 土 The nanozyme concentration was 0.1 g·kg -1 土 The method of use is to mix with water. First, disperse the nanoenzyme in water. Add 200mL of water for every kilogram of medicated soil. Keep it moist for 48 hours and then air dry it naturally. Use it as a matrix for wheat pot test. Each pot contains 200g of soil and 10 germinated wheat seeds. After 7 days, investigate the wheat plant height, root length, and fresh weight data. Figure 10 The results show that soil remediation with citric acid-modified copper peroxide nanozymes reduced wheat plant height, root length, and fresh weight by 53.37%, 28.09%, and 59.55%, respectively, compared to the unremediated soil. Simultaneously, soil remediation with the same concentration of unmodified nanocopper peroxide reduced wheat plant height, root length, and fresh weight by 30.51%, 2.24%, and -20.58%, respectively, compared to the unremediated soil. These data demonstrate that the catalytic performance of citric acid-modified copper peroxide is significantly enhanced.

[0055] Figure 10 A pot experiment was conducted to evaluate the remediation effect of nanozymes on nicosulfuron residues in soil, using wheat as an indicator plant. Substrates I-IV were blank soil control, soil remediated with citric acid-modified copper peroxide nanozymes, soil remediated with nanocopper peroxide, and unremediated nicosulfuron-containing soil.

[0056] Example 5

[0057] 1 g of polyvinyl pyrrolidone (molecular weight 10,000) was dissolved in 10 mL of an aqueous solution containing CuSO4·5H2O (10 mM), and 10 mL of a 25 mM NaOH aqueous solution and 200 μL of 30% H2O2 were added in sequence under magnetic stirring. The mixture was magnetically stirred for 20 min, and the precipitate was collected by ultracentrifugation to obtain nano-copper peroxide. The obtained nano-copper peroxide was ultrasonically dispersed in 20 mL of a 20 mM citric acid-anhydrous ethanol solution, and surface modified under magnetic stirring for 4 h. The precipitate was collected by centrifugation again, and re-dispersed and centrifuged with anhydrous ethanol for multiple washes. The precipitate was placed in a vacuum dryer for 12 h to obtain a flaky citric acid-modified copper peroxide nanozyme with a particle size of approximately 50 nm.

[0058] Figure 11 It is a citric acid-modified copper peroxide nanozyme with a particle size of about 50nm and in the form of a flake.

[0059] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a citric acid-modified copper peroxide nanozyme, comprising: Polyvinyl pyrrolidone is dissolved in a copper salt solution, and an alkaline solution and hydrogen peroxide are added to the mixed solution in sequence. An oxidation-reduction reaction is carried out under magnetic stirring conditions, and nano-copper peroxide is obtained by centrifugation. The obtained nano-copper peroxide is dispersed in a citric acid-anhydrous ethanol solution and surface modified under magnetic stirring conditions. The precipitate is collected by centrifugation, repeatedly washed with anhydrous ethanol for multiple times, and vacuum dried to obtain citric acid-modified copper peroxide nanozyme.

2. The preparation method according to claim 1, characterized in that The solvent of the copper salt solution and the alkali solution is 0-100% ethanol aqueous solution.

3. The preparation method according to claim 1, characterized in that The average molecular weight of the polyvinyl pyrrolidone is 8000, 10000, 24000, 40000, or 58000, and the concentration thereof is 1-10%.

4. The preparation method according to any one of claims 1 and 2, characterized in that The copper salt is copper sulfate, copper chloride and copper nitrate, and the solution concentration is 1-100mM.

5. The preparation method according to any one of claims 1 and 2, characterized in that: The alkali is sodium hydroxide, potassium hydroxide, and ammonia water, and the concentration of the solution is 1-200mM.

6. The preparation method according to claim 5, characterized in that The molar ratio of the copper salt to the alkali is 1:1-10.

7. The preparation method according to claim 1, characterized in that The concentration of citric acid in the citric acid-anhydrous ethanol solution is 1-100 mM.

8. The preparation method according to claim 1, characterized in that The oxidation-reduction reaction time is 5 to 120 minutes, the surface modification reaction time is 5 to 600 minutes, and the vacuum drying time is 12 to 48 hours.

9. The preparation method according to claim 1, characterized in that The particle size of the nano copper peroxide is 1 to 100 nm, and the particle size of the citric acid-modified copper peroxide nanozyme is 1 to 120 nm.

10. Use of the citric acid-modified copper peroxide nanozyme prepared by the preparation method according to claim 9 in pesticide remediation in the environment.

11. The use according to claim 10, characterized in that The environment is water and soil, and the pesticides include nicosulfuron-methyl, bensulfuron-methyl, sulfasulfuron-methyl, ethazosulfuron-methyl, pyrazosulfuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, and tribenuron-methyl.

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