A nano copper-containing magnetite and a method for efficiently degrading azole fungicides

Abstract

The present invention provides a nano copper-containing magnetite and a preparation method thereof. The nano copper-containing magnetite has magnetism, can be used as a photocatalyst, is easy to recycle, has good stability, and has good application prospects. The present invention also provides a method for efficiently degrading azole fungicides, which uses the spherical nano copper-containing magnetite prepared by the present invention as a photocatalyst and applies it to the advanced oxidation technology (SR-AOPs) based on sulfate radicals to catalyze the degradation of azole fungicides. The method is simple to operate, low in cost, has a wide pH range, and reacts quickly. The removal effect of azole fungicides is good, and the biological toxicity is greatly reduced.

Description

Technical Field

[0001] The invention specifically relates to a nano copper-containing magnetite and a method for efficiently degrading azole fungicides. Background Art

[0002] As an active ingredient that inhibits fungi, azole fungicides are widely used in human and animal health care, nursing and crop protection, and are also used in antifouling coatings and wood preservation, etc., with huge usage (Fisher MC, et al., Science, 2018, 360 (6390): 739-742). In recent years, high concentrations of azole fungicide compounds have been frequently detected in various environmental media in nature, such as surface water, sediments and farmland soil, which not only seriously affect the receiving water environment, endanger the survival of various aquatic organisms, but also pose a major threat to human health (Zhang QQ, et al., Sci Total Environ 2015, 520: 39-48). It is estimated that the annual consumption of azole fungicides climbazole (climbazole) in Europe and my country is as high as 100-1000 tons and 3800 tons (Gouin T, et al., Environ Pollut 2012, 165: 208-214). Studies have shown that azole fungicides have weak biodegradability and a certain degree of persistence. Their digestion and biodegradation capabilities in traditional pollution treatment plants and natural environments are very limited. For example, the aqueous phase removal rate of CBZ is only 34-76% (Chen ZF, et al., Water Res 2014, 52: 83-91). However, reports on the non-biological transformation and degradation of azole fungicides at home and abroad are limited to UV or UV-coupled H2O2 (Castro G, et al., Water Res 2016, 88: 681-690) and liquid chlorine systems (Cai WW, et al., Chemosphere 2019, 219: 243-249), which greatly limits our in-depth understanding of the environmental behavior and fate patterns of such pollutants. Therefore, it is crucial to select appropriate non-biological degradation, especially advanced oxidation technologies (AOPs) with strong oxidative capacity to remove or reduce their concentration levels in wastewater streams.

[0003] Magnetite and its derivative compounds M x Fe 3-x O4 (common M is Zn 2+ 、Co 2+ , Mn 2+ Mg 2+ , Cu 2+ 、Ni 2+Metal cations such as ferrous metals) are a very important class of magnetic iron oxide minerals in the surface environment. Due to its good surface adsorption and redox chemical activity, it plays an important role in Fenton-like technology with strong oxidation ability and is considered to be a class of heterogeneous catalysts with broad application prospects. In recent years, based on H2O2 as an oxidant, · The heterogeneous Fenton technology with OH as the main active species has been widely studied and has achieved good treatment results. For example, it has good surface catalytic degradation effects on highly stable organic pollutants such as organic bases, pesticides, halogenated alkanes, benzene, chlorobenzene, and nitrobenzene (Munoz M, et al., Appl Catal B-Environ 2015, 176-177: 249-265). However, H2O2 still has problems such as instability, low utilization rate, and high treatment cost during use. Compared with H2O2, persulfate has the advantages of stability and easy storage, stronger oxidizing ability, low cost, high oxidant utilization rate, and a wide reaction pH range. The SO4 ·- Therefore, researchers have shifted their focus to using persulfate as an oxidant and based on sulfate free radicals (SO4 ·- ) as the main active species in advanced oxidation technology (SR-AOPs) (Xiao S, et al., Chem Eng J 2020, 384: 123265). Compared with the heterogeneous Fenton technology, the research on the development and application of SR-AOPs catalysts is still very limited, especially the research on the degradation of azole fungicides has not been reported. Therefore, exploring green, simple and efficient SR-AOPs methods for the prevention and control of azole fungicides has important environmental significance. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the current azole fungicide pollution prevention and control and provide a nano copper-containing magnetite and a preparation method thereof. The present invention also provides a method for efficiently degrading azole fungicides. The method is simple to operate, low in cost, and has a wide pH application range. The method utilizes the strong oxidizing property of sulfate radicals, uses nano copper-containing magnetite as a photocatalyst, and uses light-coupled SR-AOPs to quickly and efficiently degrade azole fungicides in water to reduce their environmental toxicity.

[0005] To achieve the above purpose, the technical solution adopted is: a nano copper-containing magnetite, the chemical formula of the nano copper-containing magnetite is Cu x Fe 3-x O4, 0.3≤x≤0.75, the nano copper-containing magnetite is a spherical particle; preferably, the nano copper-containing magnetite is Cu 0.75 Fe 2.25 O4. The nano copper-containing magnetite is magnetic.

[0006] Preferably, the particle size of the nano copper-containing magnetite is 10 to 25 nm.

[0007] The present invention provides a method for preparing the above-mentioned nano copper-containing magnetite, comprising the following steps:

[0008] The following steps are involved:

[0009] (1a) dissolving a divalent copper salt and a divalent iron salt in water, adding an acidic pH regulator dropwise until the pH of the solution is less than 1, and introducing an inert gas for protection;

[0010] (2a) adding dropwise a solution containing an alkaline precipitant and an antioxidant;

[0011] (3a) adding a dispersant, stirring, and ultrasonically mixing to obtain a reaction mixture;

[0012] (4a) reacting the reaction mixture under microwave conditions;

[0013] (5a) After the reaction is completed, the reaction is cooled, and the black product is collected, washed, and dried to obtain the nano copper-containing magnetite.

[0014] The antioxidant prevents the ferrous iron from being oxidized.

[0015] Preferably, in step (1a), the divalent copper salt is cupric sulfate pentahydrate, and the divalent iron salt is ferrous sulfate heptahydrate.

[0016] Preferably, in step (1a), the acidic pH regulator is glacial acetic acid and the inert gas is nitrogen.

[0017] Preferably, the alkaline precipitant in step (2a) is sodium hydroxide.

[0018] Preferably, the antioxidant in step (2a) is hydrazine hydrate.

[0019] Preferably, the dispersant in step (3a) is polyethylene glycol 600.

[0020] Preferably, the molar ratio of the copper source to the iron source in step (1a) is 1:3 to 1:9. More preferably, the molar ratio of the copper source to the iron source in step (1a) is 1:3.

[0021] Preferably, the ratio of the amount of the alkaline precipitant in step (2a) to the sum of the amounts of the divalent copper salt and the divalent iron salt is 6:1 to 10:1; more preferably, the ratio of the amount of the alkaline precipitant in step (2a) to the sum of the amounts of the divalent copper salt and the divalent iron salt is 8.6:1.

[0022] Preferably, the volume ratio of the antioxidant in step (2a) to the solution in step (1a) is 1:100 to 1:200. More preferably, the volume ratio of the antioxidant in step (2a) to the solution in step (1a) is 1:120.

[0023] Preferably, the volume ratio of the dispersant in step (3a) to the solution in step (1a) is 1:4 to 1:6. More preferably, the volume ratio of the dispersant in step (3a) to the solution in step (1a) is 1:6.

[0024] Preferably, in step (4a), the reaction temperature is 90-100°C, the reaction time is 30-60 min, and the microwave power is 500-700 W. More preferably, in step (4a), the reaction temperature is 100°C, the reaction time is 60 min, and the microwave power is 600 W.

[0025] The present invention provides a method for efficiently degrading azole fungicides, the method comprising the following steps:

[0026] (1b) adding a photocatalyst to the azole fungicide solution to be treated, and stirring the solution sufficiently to allow the photocatalyst to reach adsorption equilibrium; the photocatalyst is the nano copper-containing magnetite as described in claim 1 or 2;

[0027] (2b) adding a persulfate oxidant to the azole fungicide solution of step (1b) and performing an advanced oxidation reaction under ultraviolet light to remove the azole fungicide.

[0028] Preferably, the amount of photocatalyst added in step (1b) is 0.1 to 1.0 g / L; preferably, the amount of photocatalyst added in step (1b) is 0.1 to 0.5 g / L.

[0029] Preferably, the permonosulfate oxidant in step (2b) is potassium permonosulfate complex salt (2KHSO5·KHSO4·K2SO4, PMS), and the added amount of the permonosulfate oxidant is 1.0-2.0 mmol / L; preferably, the added amount of the permonosulfate oxidant in step (2b) is 1.5 mmol / L.

[0030] Preferably, the stirring time in step (1b) is 30 to 60 minutes.

[0031] Preferably, in step (2b), the reaction temperature is 20-30°C, the reaction time is 5-60 min; in step (2b), the power of the ultraviolet lamp is 6-15 W, and the wavelength is 360-420 nm. More preferably, in step (2b), the reaction temperature is 25°C, the reaction time is 5 min; in step (2b), the power of the ultraviolet lamp is 10 W, and the wavelength is 365 nm.

[0032] Preferably, the azole fungicide in step (1b) is climbazole, the concentration of the azole fungicide in the azole fungicide solution is 0.20-4.0 μmol / L, and the pH of the azole fungicide solution is 3-9; more preferably, the concentration of the azole fungicide in the azole fungicide solution in step (1b) is 2 μmol / L, and the pH of the azole fungicide solution is 6.

[0033] Beneficial effects:

[0034] (1) The present invention provides a nano copper-containing magnetite, which can be synthesized by a microwave-assisted method, has magnetism, and can be used as a photocatalyst. Compared with homogeneous catalysts and oxides such as Co3O4, CuO, Mn3O4 and CuBi2O4 that are difficult to recycle, the easily recyclable magnetic iron oxide has outstanding advantages in environmental compatibility. At the same time, its properties and activity are not inferior to other metal-based activators. Under optimized experimental conditions, the SR-AOPs catalyzed by the nano copper-containing magnetite of the present invention has excellent catalytic degradation activity and stability for azole fungicides, and the azole fungicides are completely degraded within 5 minutes of reaction. The photocatalyst of the present invention can be recycled after recovery, and is a green, stable and efficient SR-AOPs heterogeneous catalyst.

[0035] (2) The SO4-based ·- Advanced oxidation technology with SR-AOPs as the main active species is considered to be a powerful stock to replace Fenton technology and has quite good potential application prospects. Compared with traditional water treatment methods, it has outstanding advantages such as low cost, outstanding effect, wide application range and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the X-ray diffraction pattern of the photocatalyst nano copper-containing magnetite used in Example 1 of the present invention.

[0037] Figure 2 This is a transmission electron micrograph of the photocatalyst nano-copper magnetite used in Example 1 of the present invention.

[0038] Figure 3 This is a comparison chart of the degradation performance of climbazole by the SR-AOP described in Examples 4, 10 and 11 of the present invention. DETAILED DESCRIPTION

[0039] The present invention provides a method for efficiently degrading azole fungicides, which is mainly based on the advanced oxidation technology of sulfate radicals (SR-AOPs). The present invention is described in detail below with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto.

[0040] Example 1

[0041] This embodiment provides a nano copper-containing magnetite Cu 0.75 Fe 2.25 O4, the nano copper-containing magnetite Cu 0.75 Fe 2.25 The preparation method of O4 comprises the following steps:

[0042] First, 1.5 mmol of copper sulfate pentahydrate (CuSO4·5H2O) and 4.5 mmol of ferrous sulfate heptahydrate (FeSO4·7H2O) were weighed into a three-necked round-bottom flask, 60 mL of deionized water was added and stirred thoroughly to dissolve, then 1.0 mL of glacial acetic acid was added dropwise to the solution, and nitrogen was introduced; then, the mixture was stirred at 10 mL / min. -1 A solution of 60 mL of sodium hydroxide solution (0.86 mol / L) and 0.5 mL of 80% hydrazine hydrate was added dropwise at a rate of 100 ℃; 10 mL of polyethylene glycol 600 was added as a dispersant, and the mixture was stirred and ultrasonicated for 10 min; the reaction mixture was placed in a normal pressure microwave catalytic reactor for reaction for 60 min, the microwave power was 600 W, and the reaction temperature was 100° C. After the reaction was completed, the mixture was cooled to 30° C. Black solid particles were collected by magnetic separation, and then washed repeatedly with deionized water and anhydrous ethanol for 3 times until the pH of the supernatant was neutral, and finally freeze-dried in a freeze dryer for 24 h to obtain nano copper-containing magnetite Cu 0.75 Fe 2.25 O4;Cu 0.75 Fe 2.25 O4 is spherical particles with magnetic properties and a particle size of 10 to 25 nm.

[0043] Example 2

[0044] This embodiment provides a nano copper-containing magnetite Cu 0.5 Fe 2.5 O4, the preparation method thereof is the same as that of Example 1, except that the amounts of CuSO4·5H2O and FeSO4·7H2O used are 1.0 and 5.0 mmol, respectively.

[0045] Example 3

[0046] This embodiment provides a nano copper-containing magnetite Cu 0.3 Fe 2.7O4, the preparation method thereof is the same as that of Example 1, except that the amounts of CuSO4·5H2O and FeSO4·7H2O used are 0.6 and 5.4 mmol, respectively.

[0047] Example 4

[0048] This embodiment provides a method for efficiently degrading azole fungicides, the method comprising the following steps:

[0049] First, the climbazole solution to be treated (2.0 μmol / L, pH=6) was added to the photocatalytic reactor, and the photocatalyst was added in an amount of 0.2 g / L and stirred for 30 to 60 min to reach adsorption equilibrium. The photocatalyst was the nano copper-containing magnetite Cu prepared in Example 1. 0.75 Fe 2.25 O4; then potassium permonosulfate complex salt (PMS) oxidant was added in an amount of 1.5 mmol / L, and an advanced oxidation reaction based on sulfate free radicals occurred under the irradiation of an ultraviolet lamp (power of 10 W, wavelength of 365 nm). During the reaction, circulating cooling water was introduced to maintain the reaction temperature at 25°C. Climbazole was completely removed after 5 minutes of reaction.

[0050] Example 5

[0051] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the nano copper-containing magnetite Cu 0.75 Fe 2.25 When the amount of O4 added was 0.1 g / L, climbazole was completely degraded within 5 min of reaction.

[0052] Example 6

[0053] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the nano copper-containing magnetite Cu 0.75 Fe 2.25 When the amount of O4 added was 0.5 g / L, climbazole was completely degraded within 5 min of reaction.

[0054] Example 7

[0055] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the nano copper-containing magnetite Cu 0.75 Fe 2.25 When the amount of O4 added was 1.0 g / L, climbazole was completely degraded after 10 min of reaction.

[0056] Example 8

[0057] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the photocatalyst is the nano copper-containing magnetite prepared in Example 2. 0.50 Fe 2.50 O4, climbazole was completely degraded after 60 min of reaction.

[0058] Example 9

[0059] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the photocatalyst is the nano copper-containing magnetite Cu prepared in Example 3. 0.30 Fe 2.70 O4, climbazole was completely degraded after 60 min of reaction.

[0060] Example 10

[0061] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the addition amount of potassium permonosulfate (PMS) is 2.0 mmol / L, and climbazole is completely degraded after a reaction time of 30 minutes.

[0062] Embodiment 11

[0063] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the addition amount of potassium permonosulfate (PMS) is 1.0 mmol / L, and the removal rate of climbazole is 95% after 60 minutes of reaction.

[0064] Example 12

[0065] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the initial pH of the climbazole solution to be treated is adjusted to 2.0, and the removal rate of climbazole is 95% after 60 minutes of reaction.

[0066] Embodiment 13

[0067] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the initial pH of the climbazole solution to be treated is adjusted to 3.0, and the removal rate of climbazole is 95% after 60 minutes of reaction.

[0068] Embodiment 14

[0069] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the initial pH of the climbazole solution to be treated is adjusted to 9.0, and the removal rate of climbazole is 95% after 60 minutes of reaction.

[0070] Embodiment 15

[0071] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the initial concentration of the climbazole solution to be treated is adjusted to 0.2 μmol / L, and the climbazole is completely degraded after a reaction time of 30 minutes.

[0072] Example 16

[0073] This embodiment provides a method for efficiently degrading azole fungicides. The method is the same as the method in Example 4, except that the initial concentration of the climbazole solution to be treated is adjusted to 4.0 μmol / L, and the climbazole is completely degraded after a reaction time of 15 minutes.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for degrading azole fungicides, It is characterized in that The method comprises the following steps: (1b) adding a photocatalyst to an azole fungicide solution to be treated, and stirring the solution sufficiently to allow the photocatalyst to reach adsorption equilibrium; the photocatalyst is nano copper-containing magnetite, and the amount of the photocatalyst added is 0.1-0.5 g / L; the concentration of the azole fungicide solution is 0.20-4.0 μmol / L, and the pH of the azole fungicide solution is 3-9; the particle size of the nano copper-containing magnetite is 10-25 nm; (2b) adding potassium peroxymonosulfate complex salt to the azole fungicide solution of step (1b), and performing advanced oxidation reaction at 20-30° C. for 5-60 min under ultraviolet light to remove the azole fungicide; the amount of potassium peroxymonosulfate complex salt added is 1.0-2.0 mmol / L; the power of the ultraviolet light is 6-15 W, and the wavelength is 360-420 nm; Wherein, the nano copper-containing magnetite in step (1b) is Cu 0.75 Fe 2.25 O 4 , the azole fungicide solution is a climbazole solution; the preparation method of the nano copper-containing magnetite comprises the following steps: (1a) dissolving copper sulfate pentahydrate and ferrous sulfate heptahydrate in water, adding glacial acetic acid dropwise until the pH value of the solution is less than 1, and introducing nitrogen for protection; the molar ratio of copper sulfate pentahydrate to ferrous sulfate heptahydrate is 1:3; (2a) adding dropwise a solution of sodium hydroxide and hydrazine hydrate; adding polyethylene glycol 600, stirring, and ultrasonically mixing to obtain a reaction mixture; the ratio of the amount of sodium hydroxide to the sum of the amounts of copper sulfate pentahydrate and ferrous sulfate heptahydrate is 6:1 to 10:1; the volume ratio of hydrazine hydrate to the solution obtained in step (1a) is 1:100 to 1:200; the volume ratio of polyethylene glycol 600 to the solution obtained in step (1a) is 1:4 to 1:6; (3a) The reaction mixture is reacted at 90-100°C under a microwave condition with a power of 500-700 W. After the reaction is completed, the mixture is cooled. The black product after cooling is collected, washed, and dried to obtain nano-copper magnetite.

2. The method according to claim 1, It is characterized in that The amount of potassium permonosulfate complex salt added in step (2b) is 1.5 mmol / L, the concentration of the azole fungicide solution in step (1b) is 2 μmol / L, and the pH of the azole fungicide solution is 6.

3. The method according to claim 1, It is characterized in that The reaction time in step (3a) is 30 to 60 min.

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