A method and device for constructing a microdroplet self-fenton system

Abstract

This invention discloses a method and apparatus for constructing a microdroplet self-Fenton system. The construction method includes the following steps: mixing an iron salt with an acidic solution, and subjecting the resulting mixed solution to ultrasonic atomization to form micron-sized droplets, thereby obtaining the microdroplet self-Fenton system. The construction apparatus includes an atomizing reactor for storing the mixed solution and an ultrasonic generator for providing ultrasonic waves. The microdroplet self-Fenton system constructed by this invention has the following advantages: good adaptability, enabling the acquisition of a self-Fenton system under conditions of no light, no catalyst, and no sacrificial agent; it helps to increase the generation rate and yield of ·OH in the system, giving the system stronger redox capabilities and enabling efficient degradation of organic pollutants, providing important guidance for promoting the effective treatment of organic pollutant wastewater; the process is simple, easy to operate, low in cost, environmentally friendly, suitable for industrial applications, and facilitates the effective treatment of organic pollutant wastewater.

Description

Technical Field

[0001] This invention belongs to the technical field of self-Fenton systems, and relates to a method and apparatus for constructing a microdroplet self-Fenton system. Background Technology

[0002] Fenton chemical oxidation, as an advanced oxidation treatment technology, can oxidize organic pollutants in wastewater into carbon dioxide and water in the dark. It boasts advantages such as simple operation, strong oxidizing power, high reliability, and environmental friendliness, effectively removing organic pollutants from wastewater. However, existing Fenton chemical oxidation methods require the addition of large amounts of iron salts and H₂O₂ reagents, and even more so in order to achieve Fe... 3+ / Fe 2+ The cyclical transformation requires the addition of other reducing agents, which means that the Fenton chemical oxidation method still has drawbacks such as high reagent costs in the treatment of organic pollutant wastewater. In particular, H2O2 reagent is not easy to store and the transportation process is complicated, which greatly increases the treatment cost and limits the widespread application of the Fenton chemical oxidation method in the treatment of organic pollutant wastewater.

[0003] In existing technologies, coupling Fenton chemical oxidation with photocatalysis can realize a photo-induced Fenton catalytic system. This system utilizes the photoreduction reaction of photocatalytic materials to reduce oxygen in the air to H₂O₂, while simultaneously allowing photogenerated electrons to rapidly transfer to Fe. 3+ It is reduced to Fe 2+ Promote Fe 2+ Activating the in-situ produced H2O2 generates a large amount of ·OH, thereby achieving the ability to oxidize and remove pollutants without adding H2O2. However, the above-mentioned photo-self-Fenton system and some traditional self-Fenton systems still have the following defects: (1) In most photocatalytic self-Fenton systems or traditional self-Fenton systems, the reduction of oxygen to hydrogen peroxide with two electrons and the reduction of ferric iron to ferrous iron are competitive, which will have a negative impact on the catalytic effect; (2) Self-Fenton catalysis can only be achieved under light conditions, and the adaptability is poor; (3) Photocatalytic materials still have defects such as poor oxygen adsorption capacity and poor photocatalytic capacity, resulting in low efficiency of self-produced H2O2; (4) Photocatalytic materials are difficult to separate from the system, which can easily lead to secondary pollution, or the separation operation process is complicated and the recovery cost is high; (5) The preparation process of photocatalytic materials is complicated and the preparation cost is high, which is not conducive to reducing the cost of use. Therefore, obtaining a self-Fenton system constructed under light-free, catalyst-free, and sacrificial agent-free conditions, and improving the redox capacity of this self-Fenton system to achieve efficient reduction of ferric iron to ferrous iron and efficient utilization of in-situ generated H2O2, is of great significance for promoting the widespread application of Fenton chemical oxidation in the field of organic pollutant wastewater treatment and reducing treatment costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and apparatus for constructing a microdroplet self-Fenton system under conditions of no light, no catalyst, and no sacrificial agent, in order to address the shortcomings of the existing technology.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for constructing a microdroplet self-Fenton system includes the following steps:

[0007] S1. Mix the iron salt with the acidic solution to obtain a mixed solution;

[0008] S2. The mixed solution obtained in step S1 is subjected to ultrasonic atomization to form micron-sized droplets, thus obtaining a microdroplet self-Fenton system.

[0009] In a further improvement to the above method, in step S2, an ultrasonic generator is used to perform ultrasonic atomization treatment on the mixed solution obtained in step S1.

[0010] In a further improvement to the above method, the process parameters used in step S2 during the ultrasonic atomization process are as follows: atomization rate of 3 mL / min, a particle distribution with a particle diameter of less than 4.1 μm of >65%, and a working frequency of 1.7 ± 0.17 MHz.

[0011] In a further improvement to the above method, in step S2, the ultrasonic atomization treatment is performed at a temperature of 23℃ to 27℃; and the ultrasonic atomization treatment time is 5 min to 30 min.

[0012] In a further improvement to the above method, in step S1, the pH value of the acidic solution is 2.5 to 3.

[0013] In a further improvement to the above method, in step S1, the iron salt is a ferrous salt and / or a ferric salt; the ferrous salt is at least one of ferrous chloride and ferrous sulfate; the ferric salt is at least one of ferric chloride and ferric sulfate; and the concentration of the iron salt in the mixed solution is 0.5 g / L.

[0014] As a general technical concept, the present invention also provides an apparatus for constructing the above-described microdroplet self-Fenton system, comprising an atomizing reactor for storing a mixed solution and an ultrasonic generator for providing ultrasonic waves to the atomizing reactor.

[0015] In a further improvement to the aforementioned apparatus, the ultrasonic generator includes a tank and an ultrasonic transducer for supplying ultrasonic waves to the tank; the tank contains a liquid medium, and the bottom of the atomizing reactor is disposed within the liquid medium.

[0016] In a further improvement to the aforementioned apparatus, the atomizing reactor includes a liquid storage tank, the inlet of which is connected to a feeding assembly, and a vibrating membrane is provided at the bottom of the liquid storage tank.

[0017] In a further improvement to the above-described device, the liquid storage tank is a hollow sphere; the liquid storage tank is made of glass; the feeding assembly is a conical funnel; and the feeding assembly is made of glass.

[0018] In a further improvement to the above-described device, the thickness of the oscillating membrane is 0.1 mm; the oscillating membrane is an aluminum foil or a polyethylene film.

[0019] In a further improvement to the aforementioned device, the tank is made of aluminum foil; the thickness of the aluminum foil is 0.1 mm; and the liquid medium in the tank is water.

[0020] In a further improvement to the aforementioned device, the bottom of the ultrasonic generator is also provided with a liftable base.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] (1) To address the shortcomings of existing methods for constructing self-Fenton systems, such as the need for light, catalysts, and sacrificial agents, as well as the complex processes, high costs, low efficiency of self-generated H2O2, and poor redox capabilities, this invention creatively provides a method for constructing microdroplet self-Fenton systems. By ultrasonically atomizing an iron-containing acidic solution, droplets can be atomized into micron-sized microdroplets using ultrasound. The unique high-electric-field chemical environment formed at the air-water interface of the microdroplets and the highly oxidizing ·OH, H2O2, and highly reducing e-generated ... - This invention achieves efficient reduction of ferric iron to ferrous iron in microdroplets and efficient utilization of in-situ generated H2O2, thereby forming an iron-cycle self-Fenton system. Compared with traditional photocatalytic self-Fenton systems, the method for constructing a microdroplet self-Fenton system has the following advantages: (a) Good adaptability: the iron-cycle self-Fenton system can be constructed through ultrasonic atomization, and a self-Fenton system can be obtained under conditions without light, catalyst, or sacrificial agent, thus effectively reducing the limitations imposed on the system by light, catalyst, and sacrificial agent conditions; (b) the reaction system constructed through ultrasonic atomization mitigates the competition between the two-electron reduction of oxygen to hydrogen peroxide and the reduction of ferric iron to ferrous iron in most photocatalytic self-Fenton systems or traditional self-Fenton systems. Specifically, under the strong electric field at the microdroplet interface, the separation of charge carriers is promoted, and holes are used for water oxidation to generate highly oxidizing hydroxyl radicals (·OH) to continuously produce H2O2 in situ, generating highly reducing e - Further improve conversion efficiency and rapidly convert Fe 3+Reduced to Fe 2+ This promotes Fe 2+ (c) The process is simple, easy to operate, low in cost, green and environmentally friendly, suitable for industrial application, and facilitates the effective treatment of organic pollutant wastewater; (d) The self-Fenton system constructed by activating the in-situ produced H2O2 to rapidly generate a large amount of ·OH, thereby improving the generation rate and yield of ·OH in the system. The self-Fenton system constructed by this process has stronger redox ability, which is conducive to achieving efficient degradation of organic pollutants and has important guiding significance for promoting the effective treatment of organic pollutant wastewater;

[0023] (2) This invention also provides an apparatus for constructing a microdroplet self-Fenton system, comprising an atomizing reactor containing an iron-containing acidic solution and an ultrasonic generator. The bottom of the atomizing reactor is provided with an oscillating membrane. The ultrasonic generator includes a tank and an ultrasonic transducer for supplying ultrasonic waves to the tank. The tank contains a liquid medium, and the oscillating membrane is disposed within the liquid medium. In this apparatus, electrical energy is converted into mechanical energy by the ultrasonic transducer, generating high-frequency ultrasonic waves. These ultrasonic waves are then transmitted to the iron-containing acidic solution in the atomizing reactor through the liquid medium in the tank and the oscillating membrane at the bottom of the atomizing reactor. Under the action of the ultrasonic waves, the iron-containing acidic solution is atomized into micron-sized microdroplets. The unique high-electric-field chemical environment formed at the air-water interface of the microdroplets and the highly oxidizing ·OH, H2O2, and highly reducing e-generators generated during the atomization process are utilized. - This invention enables the efficient reduction of ferric iron (Fe3+) to ferrous iron (Fe2+) in microdroplets and the efficient utilization of in-situ generated H2O2, thereby forming an iron-cycle self-Fenton system. The device of this invention is not only simple in structure and convenient for sampling, but also effectively mitigates the loss caused by droplet drift during the reaction, thus enabling the better construction of a microdroplet self-Fenton system. It has high practical value and promising application prospects. Attached Figure Description

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the device structure used to construct the microdroplet self-Fenton system in Embodiment 1 of the present invention.

[0026] Figure 2 This is a comparison chart of the degradation effects of sulfamethoxazole simulated wastewater under different reaction conditions in Example 2 of the present invention.

[0027] Figure 3 In Example 3 of this invention, Fe was involved in the reaction process of the microdroplet self-Fenton system. 2+ The concentration change graph.

[0028] Legend:

[0029] 1. Atomizing reactor; 11. Vibrating membrane; 21. Tank; 22. Ultrasonic transducer; 3. Base; a. Iron-containing acidic solution; b. Liquid medium. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0031] The materials and instruments used in the following examples are all commercially available.

[0032] Example 1:

[0033] A method for constructing a microdroplet self-Fenton system, specifically utilizing... Figure 1 The apparatus shown constructs a microdroplet self-Fenton system, comprising the following steps:

[0034] (1) Weigh 7.5 mg of anhydrous ferric chloride powder and mix it with 15 mL of hydrochloric acid solution with a pH of 2.5. After dissolving, mix evenly to obtain a mixed solution.

[0035] (2) Transfer the mixed solution obtained in step (1) to the atomizing reactor, turn on the power of the ultrasonic transducer, and perform ultrasonic atomization treatment on the mixed solution at 25°C for 20 min. The process parameters used in the ultrasonic atomization treatment are: atomization rate of 3 mL / min, a droplet distribution of >65% of droplets with a diameter of less than 4.1 μm, and a working frequency of 1.7 ± 0.17 MHz. In this process, the ultrasonic transducer converts electrical energy into mechanical energy and generates high-frequency ultrasonic waves. The ultrasonic waves are then transmitted to the iron-containing acidic solution in the atomizing reactor through the liquid medium in the tank and the oscillating membrane at the bottom of the atomizing reactor. Under the action of ultrasonic waves, the iron-containing acidic solution is atomized into micron-sized droplets. The unique high electric field chemical environment formed by the air-water interface of the droplets and the highly oxidizing ·OH, H2O2 and highly reducing e- generated during the atomization process are utilized. - This enables the efficient reduction of ferric iron to ferrous iron in microdroplets and the efficient utilization of in-situ generated H2O2, thereby forming an iron-cycle self-Fenton system and obtaining a microdroplet self-Fenton system.

[0036] In this embodiment, the apparatus used to construct the microdroplet self-Fenton system is, for example... Figure 1 As shown, the atomizing reactor 1 includes an atomizing reactor 1 for storing an iron-containing acidic solution a (i.e., the mixed solution in this embodiment) and an ultrasonic generator for providing ultrasonic waves to the atomizing reactor 1. The ultrasonic generator includes a tank 21 and an ultrasonic transducer 22 for providing ultrasonic waves to the tank 21. The tank is filled with a liquid medium b, and the bottom of the atomizing reactor 1 is disposed in the liquid medium b.

[0037] In this embodiment, an oscillating membrane 11 is provided at the bottom of the atomizing reactor 1, and the oscillating membrane 11 is disposed in the liquid medium b. In this embodiment, the ultrasonic transducer is made of piezoelectric ceramic material, which can convert electrical energy into mechanical energy and generate high-frequency ultrasonic waves. Then, through the water in the tank 21 and the oscillating membrane 11 at the bottom of the atomizing reactor 1, the ultrasonic waves are transmitted to the iron-containing acidic solution, and the iron-containing acidic solution is atomized into micron-sized, fine droplets.

[0038] In this embodiment, the atomizing reactor 1 includes a liquid storage tank, with a feeding component connected to the inlet of the storage tank. A vibrating membrane 11 is installed at the bottom of the storage tank. The storage tank is a hollow sphere made of glass. The feeding component is a conical funnel made of glass. The vibrating membrane 11 is made of aluminum foil with a thickness of 0.1 mm. Specifically, in this embodiment, the atomizing reactor 1 is composed of a splash-proof glass sphere and a spherical funnel. During use, this not only facilitates sampling but also effectively mitigates the loss caused by microdroplets drifting away during the reaction, thereby achieving better internal circulation atomization degradation.

[0039] In this embodiment, the tank 21 is made of aluminum foil with a thickness of 0.1 mm, and the liquid medium b in the tank 21 is water.

[0040] In this embodiment, the bottom of the ultrasonic generator is provided with a height-adjustable base 3. By adjusting the up-and-down movement of the base 3, the atomization effect of the ultrasonic waves on the ferric acid solution can be controlled.

[0041] Example 2:

[0042] The degradation effect of the microdroplet self-Fenton system of the present invention on organic pollutants was investigated, including the following steps:

[0043] Measure 15 mL of 10 mg / L sulfamethoxazole simulated wastewater, adjust the pH of the wastewater to 2.5 with 0.2 mol / L hydrochloric acid, weigh 7.5 mg of anhydrous FeCl3 powder and add it to the simulated wastewater. After dissolving and mixing, transfer the solution to a container as shown in the image. Figure 1 In the atomizing reactor shown, the power to the ultrasonic transducer was turned on to start the reaction (ultrasonic atomization treatment), causing the mixed solution to be atomized into micron-sized droplets, thus constructing a microdroplet self-Fenton system. During the reaction, the temperature of the reaction solution in the reactor was controlled at 25°C by adding ice packs to the water tank. At reaction times of 0 min, 5 min, 10 min, 15 min, and 20 min, 0.5 mL of the reaction solution was pipetted, filtered through a 0.22 μm organic filter membrane, and the absorbance was measured using a high-performance liquid chromatograph to determine the concentration of each pollutant after degradation at each time point and analyze its degradation status.

[0044] Experimental control groups were set up under different reaction conditions:

[0045] ① Pure microdroplet system: Except for not adding 7.5 mg of anhydrous FeCl3 powder, the other conditions are the same as those for the microdroplet self-Fenton system described above.

[0046] ② Non-microdroplet / H2O2 system: Measure 15 mL of 10 mg / L sulfamethoxazole simulated wastewater, adjust the pH of the wastewater to 2.5 with 0.2 mol / L hydrochloric acid, add 66.6 μL of 0.12 mol / L H2O2 dilution (derived from twice the amount of H2O2 accumulated in the pure microdroplet system in Example 1 after 20 min of reaction), mix well, transfer to a 50 mL glass beaker, place it on a magnetic stirrer, set the speed to 500 rpm, and at reaction times of 0 min, 5 min, 10 min, 15 min, and 20 min, use a pipette to take 0.5 mL of the reaction solution, filter it through a 0.22 μm organic filter membrane, and use a high performance liquid chromatograph to measure the absorbance to determine the concentration of each pollutant after degradation at each time point and analyze its degradation status.

[0047] ③ Non-microdroplet / H2O2 / Fe(Ⅲ) system: 15 mL of 10 mg / L sulfamethoxazole simulated wastewater was measured, and the pH value of the wastewater was adjusted to 2.5 with 0.2 mol / L hydrochloric acid. 7.5 mg of anhydrous FeCl3 powder and 66.6 μL of 0.12 mol / L H2O2 dilution (derived from twice the amount of H2O2 accumulated in the pure microdroplet system after 20 min of reaction in Example 1) were added to the simulated wastewater in sequence. After mixing, the mixture was transferred to a 50 mL glass beaker and placed on a magnetic stirrer with a speed of 500 rpm. At reaction times of 0 min, 5 min, 10 min, 15 min, and 20 min, 0.5 mL of the reaction solution was pipetted and filtered through a 0.22 μm organic filter membrane. The absorbance was measured using a high-performance liquid chromatograph to determine the concentration of each pollutant after degradation at each time point and to analyze the degradation status.

[0048] Figure 2 This is a comparison chart showing the degradation effect of sulfamethoxazole simulated wastewater under different reaction conditions in Example 2 of the present invention. Figure 2It can be seen that, under different reaction systems, when the total reaction time is 20 min, the degradation rates of sulfonamides in the microdroplet self-Fenton system, pure microdroplet system, non-microdroplet / H2O2 system, and non-microdroplet / H2O2 / Fe(Ⅲ) system are 100%, 96%, 3%, and 24%, respectively. Among them, the degradation rate of sulfonamides in the microdroplet self-Fenton system can reach 93% when the reaction time is 10 min, which is 2.5 times that of the pure microdroplet system and 5 times that of the non-microdroplet / H2O2 / Fe(Ⅲ) system. This indicates that the microdroplet self-Fenton system constructed in this invention can achieve in-situ, continuous, self-production, and efficient utilization of H2O2 without the addition of light, catalysts, or sacrificial agents, based on the pure microdroplet system, to generate a greater amount of reactive oxygen species (ROS), thereby accelerating the slow chemical reaction in the non-microdroplet / H2O2 / Fe(Ⅲ) system in the bulk solution.

[0049] In addition, in this embodiment, the accumulation of H2O2 in the pure microdroplet system was also tested. Specifically, after ultrasonic nebulization for 20 min, the reaction was interrupted, 3 mL of the reaction solution was pipetted into a 5 mL centrifuge tube, and then 1 mL of potassium iodide (0.4 mol / L) solution and 1 mL of potassium hydrogen phthalate (0.1 mol / L) were added to the centrifuge tube and shaken well. After standing for 30 min for color development, the absorbance was measured with a UV spectrophotometer. The results showed that the accumulation of H2O2 in the system after ultrasonic nebulization for 20 min was 4.068 μmol.

[0050] Example 3:

[0051] The study investigated the changes in ferrous ion content during the degradation of organic pollutant wastewater using the microdroplet self-Fenton system of this invention, including the following steps:

[0052] Measure 15 mL of simulated sulfamethoxazole wastewater at a concentration of 10 mg / L. Adjust the pH of the wastewater to 2.5 with 0.2 mol / L hydrochloric acid. Weigh 7.5 mg of anhydrous FeCl3 powder and add it to the simulated wastewater. After dissolving and mixing, take 1 mL of the reaction stock solution into a 10 mL centrifuge tube, add 0.4 mL of 1,10-o-phenanthroline solution (1.2 g / L) and 2 mL of sodium acetate solution (pH = 4.6), add deionized water to the 10 mL mark, shake well, and let stand for 5 min to develop color. Measure the initial absorbance with a UV spectrophotometer. Then transfer 10 mL of the colorimetric solution to the reactor, turn on the power of the ultrasonic transducer, and start the reaction (ultrasonic atomization treatment) to atomize the mixed solution into micron-sized droplets, constructing a microdroplet self-Fenton system. During the reaction, the temperature of the reaction solution in the reactor is controlled at 25℃ by adding ice packs to the water tank. Using in-situ color development, intermittent reaction, and sampling methods, 3 mL of reaction solution was taken at reaction times of 5 min, 10 min, 15 min, and 20 min. No filtration was required, and the initial absorbance was measured using a UV spectrophotometer. The concentration of ferrous ions at each time point was monitored. After the measurement was completed, the solution was poured back into the reactor to continue the reaction.

[0053] Figure 3 In Example 3 of this invention, Fe was involved in the reaction process of the microdroplet self-Fenton system. 2+ The concentration change graph. (From...) Figure 3 It can be seen that during the reaction time of 0–5 min, the ferrous ion concentration increased rapidly, from the initial background value of 0.066 mM to 0.705 mM, indicating that the microdroplet self-Fenton system constructed in this invention does indeed promote the efficient conversion between ferric and ferrous iron in the solution. During the reaction time of 5–10 min, the ferrous ion concentration reached 0.907 mM, and compared to 0–5 min, the increase in ferrous ion concentration was significantly reduced. The changes in ferrous ion concentration were not significant during the reaction times of 10–15 min and 15–20 min, possibly because the cyclic conversion between ferrous and ferric iron tended towards an equilibrium state. In summary, the microdroplet self-Fenton system constructed in this invention can effectively promote the iron cycle process between ferric and ferrous iron in microdroplets without the addition of light, catalysts, or sacrificial agents, based on a pure microdroplet system. This enables in-situ, continuous, self-production, and efficient utilization of H2O2, generating a greater abundance of reactive oxygen species (ROS), and accelerating the slow chemical reactions in the non-microdroplet / H2O2 / Fe(Ⅲ) system in the bulk solution.

[0054] The results above show that, compared with traditional photocatalytic self-Fenton systems, the method constructed in this invention has the following advantages: (a) Good adaptability; an iron-cycle self-Fenton system can be constructed through ultrasonic atomization, and a self-Fenton system can be obtained under conditions of no light, no catalyst, and no sacrificial agent, thus effectively reducing the limitations imposed on the system by light, catalyst, sacrificial agent, etc.; (b) The reaction system constructed through ultrasonic atomization mitigates the competition between the two-electron reduction of oxygen to hydrogen peroxide and the reduction of ferric iron to ferrous iron in most photocatalytic self-Fenton systems or traditional self-Fenton systems. Specifically, under the strong electric field at the microdroplet interface, the separation of charge carriers is promoted, and holes are used for water oxidation to generate highly oxidizing hydroxyl radicals (·OH) to continuously produce H2O2 in situ, generating highly reducing e - Further improve conversion efficiency and rapidly convert Fe 3+ Reduced to Fe 2+ This promotes Fe 2+ (c) The process is simple, easy to operate, low in cost, green and environmentally friendly, suitable for industrial application, and facilitates the effective treatment of organic pollutant wastewater; (d) The self-Fenton system constructed by activating the in-situ produced H2O2 to rapidly generate a large amount of ·OH, thereby improving the generation rate and yield of ·OH in the system. The self-Fenton system constructed by this process has stronger redox ability, which is conducive to achieving efficient degradation of organic pollutants and has important guiding significance for promoting the effective treatment of organic pollutant wastewater;

[0055] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing a microdroplet self-Fenton system, characterized in that, Includes the following steps: S1. Mix the iron salt with an acidic solution to obtain a mixed solution; the pH value of the acidic solution is 2.5-3; the iron salt is a ferric salt. S2. The mixed solution obtained in step S1 is subjected to ultrasonic atomization to form micron-sized droplets, thus obtaining a microdroplet self-Fenton system. The process parameters used in the ultrasonic atomization process are: atomization rate of 3 mL / min, droplet distribution with a percentage of droplets smaller than 4.1 μm in diameter >65%, and working frequency of 1.7 ± 0.17 MHz. The ultrasonic atomization time is 5 min to 30 min.

2. The method according to claim 1, characterized in that, In step S2, the mixed solution obtained in step S1 is subjected to ultrasonic atomization treatment using an ultrasonic generator.

3. The method according to claim 2, characterized in that, In step S2, the ultrasonic atomization treatment is performed at a temperature of 23℃~27℃.

4. The method according to any one of claims 1 to 3, characterized in that, In step S1, the ferric salt is at least one of ferric chloride and ferric sulfate; the concentration of the ferric salt in the mixed solution is 0.5 g / L.

5. An apparatus for constructing the microdroplet self-Fenton system according to any one of claims 1 to 4, characterized in that, It includes an atomizing reactor for storing a mixed solution and an ultrasonic generator for supplying ultrasonic waves to the atomizing reactor.

6. The apparatus according to claim 5, characterized in that, The ultrasonic generator includes a tank and an ultrasonic transducer for supplying ultrasonic waves to the tank; the tank is filled with a liquid medium, and the bottom of the atomizing reactor is disposed in the liquid medium.

7. The apparatus according to claim 6, characterized in that, The atomizing reactor includes a liquid storage tank, the inlet of which is connected to a feeding assembly, and a vibrating membrane at the bottom of the liquid storage tank. The liquid storage tank is a hollow sphere and is made of glass. The feeding assembly is a conical funnel and is also made of glass. The vibrating membrane has a thickness of 0.1 mm and is made of polyethylene film.

8. The apparatus according to claim 6 or 7, characterized in that, The tank is made of aluminum foil; the thickness of the aluminum foil is 0.1 mm; the liquid medium in the tank is water; and the bottom of the ultrasonic generator is also provided with a liftable base.

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