Method and application of effectively controlling iron circulation on micron zero-valent iron surface

Abstract

The present invention relates to a method and application for effectively regulating the iron circulation on the surface of micron zero-valent iron. The micron zero-valent iron particles are modified by introducing L-ascorbic acid 2-phosphate sesquimagnesium salt, a precursor of L-ascorbic acid, thereby significantly improving the reduction performance of zero-valent iron and promoting the circulation of iron substances. Chromium pollutants can be quickly removed by mechanical stirring for 10 minutes in an aerobic environment. The introduction of L-ascorbic acid 2-phosphate sesquimagnesium salt in the present invention can effectively regulate the iron circulation on the surface of the particles, improve its electron transfer efficiency, significantly improve the hydrophobicity of the material, and overcome the shortcomings of traditional zero-valent iron such as easy passivation, low electron selectivity, and slow surface iron circulation rate. The modified micron zero-valent iron material is environmentally friendly and pollution-free, has a high reusability rate, and a high electron utilization rate, providing an innovative solution for the efficient treatment of chromium-containing industrial wastewater and other heavy metal wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental remediation, and relates to a method for successfully preparing modified micron zero-valent iron materials by regulating the iron circulation on the surface of zero-valent iron using L-ascorbic acid 2-phosphate sesquimagnesium salt, and applying the materials in the treatment of chromium-containing heavy metal wastewater. Background Art

[0002] Hexavalent chromium (Cr(VI)) is a common and highly toxic pollutant in industrial wastewater and groundwater. It is highly soluble and mobile, and can spread rapidly in the environment, contaminating groundwater, soil, and the food chain. It can cause cancer, respiratory diseases, and skin ulcers through drinking water or skin contact. In addition, long-term exposure to low concentrations of hexavalent chromium can cause chronic damage to the liver, kidneys, and immune system, and even lead to gene mutations. Therefore, Cr(VI) is significantly harmful to the human body and the ecological environment. Zero-valent iron, as an environmentally friendly, inexpensive and readily available reducing substance, can reduce hexavalent chromium (Cr(VI)) to non-toxic trivalent chromium (Cr(III)). However, the practical application of zero-valent iron is limited by its shortcomings, such as easy surface passivation and low electron utilization. Therefore, modifying zero-valent iron to improve its decontamination performance is currently a hot topic of concern for many researchers.

[0003] Zero-valent iron removes Cr(VI) primarily through adsorption, reduction, and coprecipitation. The reduction effect is primarily attributed to the gradual release of Fe(II) from the zero-valent iron (Equations 1-2). Furthermore, an Fe(III) / Fe(II) cycle (Equation 3) occurs on the zero-valent iron surface, ensuring the continuous generation of Fe(II) and reducing iron precipitation during the reaction. Therefore, exploring efficient methods for regulating the iron cycle on the zero-valent iron surface will help improve its reactivity and achieve more effective decontamination.

[0004] Fe 0 +2H + →Fe(II)+H2 (1)

[0005] 2Fe 0 +2H2O+O2→2Fe(II)+4OH - (2)

[0006] Fe 0 +2Fe(III)→3Fe(II) (3)

[0007] Chinese patent document CN202111043953.2 discloses a sulfurized modified micron zero-valent iron material, its preparation method and application, but the sulfurization modification process produces harmful gas hydrogen sulfide and the material preparation time is long.

[0008] Zhou et al. used L-cysteine ​​to modify zero-valent iron using the ball milling method, which reduced the redox potential of the Fe(III) / Fe(II) cycle and promoted the Fe 0 Surface Fe(III) / Fe(II) cycle. However, the material preparation method is energy-intensive, the preparation process is too cumbersome and complicated, and the reusability is poor (J. Hazard. Mater, 2023, 456, 131717). Summary of the Invention

[0009] In view of the above-mentioned status of the existing technology, especially the problems of easy passivation of the zero-valent iron surface, slow iron circulation rate, and low electron utilization, the present invention uses L-ascorbic acid 2-phosphate sesquimagnesium salt to achieve effective regulation and modification of the iron circulation on the surface of micron zero-valent iron. The micron zero-valent iron material after regulation and modification can quickly remove hexavalent chromium in water.

[0010] Therefore, an object of the present invention is to provide a method for effectively regulating the iron cycle on the surface of micronized zero-valent iron.

[0011] The second object of the present invention is to provide a micron zero-valent iron material regulated and modified by the above method.

[0012] The third object of the present invention is to provide the use of the modified micron zero-valent iron material regulated by the above method in the treatment of chromium-containing wastewater.

[0013] The technical solution for achieving the above-mentioned invention object can be summarized as follows:

[0014] A method for effectively regulating the iron cycle on the surface of micron zero-valent iron is provided, wherein an L-ascorbic acid 2-phosphate sesquimagnesium salt solution is mixed with the zero-valent iron to carry out a modification reaction.

[0015] According to the present invention, a micronized zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt is also provided, wherein the iron source is micronized zero-valent iron, the modifier is L-ascorbic acid 2-phosphate sesquimagnesium salt, and the molar ratio of the iron source to the modifier is 1:(0.05-0.06), and most preferably 1:0.056.

[0016] According to the present invention, the method for preparing the micronized zero-valent iron material modified by the L-ascorbic acid 2-phosphate sesquimagnesium salt comprises the following steps:

[0017] The zero-valent iron is pickled with acetic acid-sodium acetate buffer in an oxygen-free environment to remove the passivation layer on the surface, and then L-ascorbic acid 2-phosphate sesquimagnesium salt solution is added and shaken to react. The suspension after the reaction is filtered and freeze-dried to obtain the micron zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt.

[0018] According to the present invention, preferably, the zero-valent iron is micron zero-valent iron, and the particle size is 70-80 μm.

[0019] According to the present invention, preferably, the pH of the acetic acid-sodium acetate buffer solution is 4, and the concentration is 0.2 mol / L.

[0020] According to the present invention, preferably, the concentration of the L-ascorbic acid 2-phosphate sesquimagnesium salt solution is 0.1 mol / L.

[0021] According to the present invention, preferably, the molar ratio of zero-valent iron to L-ascorbic acid 2-phosphate sesquimagnesium salt is 1:(0.05-0.06), most preferably 1:0.056.

[0022] According to the present invention, preferably, the time for the micron zero-valent iron particles to oscillate and react in a buffer solution to remove the passivation film in an oxygen-free environment is 10 minutes.

[0023] According to the present invention, preferably, the oscillation reaction time is 10 h and the temperature is 25°C.

[0024] According to the present invention, the micronized zero-valent iron material modified by the above-mentioned L-ascorbic acid 2-phosphate sesquimagnesium salt is used to treat chromium-containing heavy metal wastewater.

[0025] According to the present invention, there is also provided a method for rapidly treating chromium-containing heavy metal wastewater, comprising the following steps:

[0026] The micron zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt is put into chromium-containing heavy metal wastewater, and the hexavalent chromium in the solution is quickly removed through mechanical stirring under an aerobic environment.

[0027] According to the present invention, preferably, the stirring paddle used for mechanical stirring during the pollutant removal process is made of polytetrafluoroethylene, and the rotation speed of the stirring paddle during mechanical stirring is 400±10r / min, and the hexavalent chromium pollutants can be completely removed within 10 minutes.

[0028] According to the present invention, preferably, the dosage of the modified micron zero-valent iron material regulated by L-ascorbic acid 2-phosphate sesquimagnesium salt is 0.1-0.3 g / L, most preferably 0.2 g / L.

[0029] According to the present invention, preferably, the reaction background solution for treating chromium-containing heavy metal wastewater is acetic acid-sodium acetate buffer solution, pH=5, and the solution concentration is 0.1-0.3 mol / L, most preferably 0.2 mol / L.

[0030] Beneficial effects of the present invention:

[0031] 1. The zero-valent iron particles (L-ZVI) modified by L-ascorbic acid 2-phosphate sesquimagnesium salt in the present invention have a significantly increased specific surface area compared to unmodified zero-valent iron (ZVI). The introduction of the modifier also promotes the circulation of iron elements on the particle surface, promotes the cyclic regeneration and release of Fe(II), and improves its reduction performance.

[0032] 2. The zero-valent iron particles modified with L-ascorbic acid 2-phosphate sesquimagnesium salt significantly enhance the ability to remove hexavalent chromium from water. Removal experiments on chromium-containing heavy metal wastewater revealed that the material completely removed Cr(VI) in just 10 minutes in an acetic acid-sodium acetate buffer solution at pH 5. Under the same conditions, the original micronized zero-valent iron material required 180 minutes to achieve the same removal efficiency.

[0033] 3. The modifier, L-ascorbic acid 2-phosphate sesquimagnesium salt, is safe and pollution-free and can be used as a food additive. It can regulate the interface of micronized zero-valent iron particles, significantly improving the performance of zero-valent iron materials and, to some extent, overcoming the inherent problems of easy passivation, low electron selectivity, and slow surface iron circulation rate of zero-valent iron materials.

[0034] 4. The raw materials of the present invention are cheap and easily available, environmentally friendly, and the preparation process is simple and easy to operate. The modified zero-valent iron material has excellent decontamination performance and excellent reusability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scanning electron microscope image of commercially purchased micronized zero-valent iron material;

[0036] Figure 2 This is an electron microscope scanning image of the micronized zero-valent iron material whose surface has been regulated by iron circulation in Example 1;

[0037] Figure 3 This is the element mapping diagram of the micron zero-valent iron material whose surface has been regulated by iron circulation in Example 1;

[0038] Figure 4 This is the XPS (X-ray photoelectron spectroscopy) analysis chart of commercially purchased micron zero-valent iron material;

[0039] Figure 5 This is an XPS (X-ray photoelectron spectroscopy) analysis diagram of the modified micron zero-valent iron material whose surface has been regulated by iron cycling in Example 1;

[0040] Figure 6 This is a comparison of the Tafel plots of commercially available micronized zero-valent iron (ZVI) and modified micronized zero-valent iron (L-ZVI) with surface iron cycling regulation.

[0041] Figure 7is a comparison diagram of the concentration change curve of the Cr(VI) removal process in Experimental Example 1;

[0042] Figure 8 This is a comparison chart of reaction rate constants of the pseudo-first-order kinetic reaction fitting of the Cr(VI) removal process in Experimental Example 1.

[0043] Figure 9 This is a comparison chart of the concentration change curves during the reaction process of the cyclic experiment of the material of Example 1 and the commercial zero-valent iron material in Experimental Example 2. DETAILED DESCRIPTION

[0044] The present invention involves pickling micronized zero-valent iron in an anaerobic environment to remove its surface passivation layer, then adding a modifier, L-ascorbic acid 2-phosphate sesquimagnesium salt, to synthesize a modified material, L-ZVI, to achieve efficient regulation of iron circulation on the surface of the zero-valent iron. This material is then added to chromium-containing heavy metal wastewater, where it is mechanically stirred under aerobic conditions to rapidly remove hexavalent chromium contaminants. The introduction of L-ascorbic acid 2-phosphate sesquimagnesium salt effectively regulates iron circulation on the surface of micronized zero-valent iron particles, improving their electron transfer efficiency and significantly enhancing the material's hydrophobicity, overcoming the shortcomings of traditional zero-valent iron, such as easy passivation, low electron selectivity, and slow surface iron circulation rate.

[0045] The present invention provides a method for effectively regulating iron circulation on the surface of micronized zero-valent iron. The method comprises mixing a solution of L-ascorbic acid 2-phosphate sesquimagnesium salt with zero-valent iron to perform a modification reaction. L-ascorbic acid can reduce Fe(III) to Fe(II) due to its strong reducing properties, but L-ascorbic acid itself is unstable and easily oxidized. Therefore, the present invention selects its precursor, i.e., the stable L-ascorbic acid 2-phosphate sesquimagnesium salt, as a modifier to react with zero-valent iron to prepare the material. L-ascorbic acid 2-phosphate sesquimagnesium salt exists in various forms and can be used in the present invention in the form of L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate.

[0046] The introduction of these modifiers altered the structure of the passivation layer on the surface of the micronized zero-valent iron particles, promoting the circulation of iron species on the surface. Furthermore, the modified micronized zero-valent iron exhibited significantly enhanced reducibility and accelerated electron transfer, enabling rapid removal of chromium contaminants with just 10 minutes of mechanical stirring in an aerobic environment.

[0047] According to the present invention, the micron zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt is prepared, wherein the iron source is micron zero-valent iron and the modifier is L-ascorbic acid 2-phosphate sesquimagnesium salt.

[0048] In one or more preferred embodiments, the molar ratio of the iron source to the modifier is 1:(0.05-0.06), most preferably 1:0.056.

[0049] According to the present invention, the method for preparing the micronized zero-valent iron material modified by the L-ascorbic acid 2-phosphate sesquimagnesium salt comprises the following steps:

[0050] The zero-valent iron is washed with acetic acid-sodium acetate buffer in an oxygen-free environment to remove the surface passivation layer. A solution of L-ascorbic acid 2-phosphate sesquimagnesium salt is then added and shaken to react. The resulting suspension is filtered and freeze-dried to obtain the L-ascorbic acid 2-phosphate sesquimagnesium salt-modified micronized zero-valent iron material. This material can be sealed in a vacuum bag for storage.

[0051] In one or more preferred embodiments, the zero-valent iron is micron zero-valent iron, and the particle size is 70-80 μm.

[0052] In one or more preferred embodiments, the pH of the acetic acid-sodium acetate buffer solution is 4, and the concentration is 0.2 mol / L.

[0053] In one or more preferred embodiments, the concentration of the L-ascorbic acid 2-phosphate sesquimagnesium salt solution is 0.1 mol / L.

[0054] In one or more preferred embodiments, the molar ratio of zero-valent iron to L-ascorbic acid 2-phosphate sesquimagnesium salt is 1:(0.05-0.06), most preferably 1:0.056.

[0055] In one or more preferred embodiments, the time for removing the passivation film by oscillating the micron zero-valent iron particles in the buffer solution in an oxygen-free environment is 10 minutes.

[0056] In one or more preferred embodiments, the shaking reaction time is 10 h and the temperature is 25°C.

[0057] According to the present invention, the micronized zero-valent iron material modified by the above-mentioned L-ascorbic acid 2-phosphate sesquimagnesium salt is used to treat chromium-containing heavy metal wastewater.

[0058] According to the present invention, there is also provided a method for rapidly treating chromium-containing heavy metal wastewater, comprising the following steps:

[0059] The micron zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt is put into chromium-containing heavy metal wastewater, and the hexavalent chromium in the solution is quickly removed through mechanical stirring under an aerobic environment.

[0060] In one or more preferred embodiments, the stirring paddle used for mechanical stirring during the pollutant removal process is made of polytetrafluoroethylene, and the rotation speed of the stirring paddle during mechanical stirring is 400±10 r / min, and the hexavalent chromium pollutants can be completely removed within 10 minutes.

[0061] In one or more preferred embodiments, the dosage of the modified micron zero-valent iron material regulated by L-ascorbic acid 2-phosphate sesquimagnesium salt is 0.1-0.3 g / L, most preferably 0.2 g / L.

[0062] In one or more preferred embodiments, the reaction background solution for treating chromium-containing heavy metal wastewater is acetic acid-sodium acetate buffer solution, pH=5, and the solution concentration is 0.1-0.3 mol / L, most preferably 0.2 mol / L.

[0063] In one or more preferred embodiments, the modified micron zero-valent iron material is used to treat chromium-containing heavy metal wastewater, and the Cr(VI) concentration of the chromium-containing wastewater is 5 mg / L.

[0064] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

[0065] Example 1

[0066] The preparation method of the micronized zero-valent iron material with L-ascorbic acid 2-phosphate sesquimagnesium salt regulating iron circulation is as follows:

[0067] A 250ml volumetric flask was used to prepare a pH=4, 0.2mol / L acetic acid-sodium acetate buffer solution, which was then transferred to a 250ml serum bottle. Nitrogen was continuously added to the bottle until the dissolved oxygen meter displayed a reading of 0 (approximately 30 minutes). 1g of iron powder was weighed and added to the bottle, and the bottle mouth was quickly sealed with a rubber stopper. The sealed serum bottle was placed in a tumble shaker with a speed of 120r / min and an ambient temperature of 25±1°C for 10 minutes. A preliminary acid wash was performed to remove the surface passivation layer. After 10 minutes, the serum bottle was taken out and 10ml of a 0.1mol / L L-ascorbic acid 2-phosphate sesquimagnesium salt solution was quickly drawn using a 10ml syringe. The prepared solution was injected into the serum bottle through the rubber stopper of the bottle mouth. The serum bottle was then immediately placed in the tumble shaker again and the reaction continued for 10 hours. The suspension after the reaction was filtered, and the material was freeze-dried in a vacuum drying oven for 2 hours. After drying, it was sealed in a vacuum bag for storage.

[0068] The electron microscope scanning image of commercially purchased micron zero-valent iron material is as follows Figure 1 As shown, the electron microscope scanning image of the micron zero-valent iron material whose surface has been regulated by iron circulation in this embodiment is as follows Figure 2 As shown. Figure 1 、 Figure 2It can be seen that compared with the relatively smooth surface of the commercially purchased micron zero-valent iron material, the surface of the modified material in Example 1 is relatively rough, with obvious pores and cracks. This porous microstructure provides more active reaction sites, helps to increase the specific surface area, thereby improving the mass transfer efficiency between the reactants and accelerating the reaction rate.

[0069] The molar ratio of the iron source to the modifier L-ascorbic acid 2-phosphate sesquimagnesium salt in this embodiment is 1:0.056. The mapping diagram of the elements contained in the modified material is as follows: Figure 3 shown.

[0070] The XPS images of the commercially purchased micron zero-valent iron material and the modified material of this embodiment are shown in FIG. Figure 4-5 As shown. Figure 4 、 Figure 5 It can be seen that although the types of elements on the particle surface have not changed, a comparison of the two shows that compared with the commercially purchased micron zero-valent iron material (ZVI, Fe(II) accounts for 24.53%), the Fe(II) content on the surface of the modified particles has increased to 49.20%, and the corresponding Fe(III) content has decreased from 75.47% to 50.8%. The increase in the proportion of divalent iron has improved the reducibility of the modified material.

[0071] The comparison of Tafel curves of commercially purchased micron zero-valent iron material (ZVI) and the modified micron zero-valent iron material (L-ZVI) with iron cycle regulation on the surface of this embodiment is shown in the figure. Figure 6 As shown. Figure 6 It can be seen that L-ZVI (-0.962V) has a more negative corrosion potential than ZVI (-0.92V), and L-ZVI exhibits a higher current density and a significantly negative shift in peak potential during the reduction process, indicating that L-ZVI has superior electron transfer ability and significantly improved electrochemical activity.

[0072] Example 2

[0073] The material prepared in Example 1 was used to treat heavy metal wastewater containing chromium. The concentration of the chromium-containing wastewater to be treated was 5 mg / L, and the reaction background solution was an acetic acid-sodium acetate buffer solution with a pH of 5.

[0074] The specific steps are as follows:

[0075] Transfer 500 ml of the prepared acetic acid-sodium acetate buffer solution to a 500 ml beaker, add 1 ml of chromium stock solution (concentration of 2500 mg / L) to make the chromium concentration of the reaction system 5 mg / L, then weigh 0.1 g of the modified material and add it to the beaker to start the reaction. Mechanical stirring is carried out under an aerobic environment at a speed of 400±10 r / min. The Cr(VI) removal rate can reach 100% within 10 minutes of reaction.

[0076] Example 3

[0077] As described in Example 1, except that:

[0078] The molar ratio of the iron source to the modifier L-ascorbic acid 2-phosphate sesquimagnesium salt is 1:0.05.

[0079] Example 4

[0080] As described in Example 1, except that:

[0081] The molar ratio of the iron source to the modifier L-ascorbic acid 2-phosphate sesquimagnesium salt is 1:0.06.

[0082] Comparative Example 1

[0083] As described in Example 1, except that: after the zero-valent iron was pickled for 10 minutes, sodium sulfide solution was added and the reaction was continued for 10 hours, and the molar ratio of iron to sulfur was 1:0.056 to obtain the material.

[0084] Comparative Example 2

[0085] As described in Example 1, except that after the zero-valent iron was pickled for 10 minutes, L-ascorbic acid solution was added and the reaction was continued for 10 hours, and the molar ratio of L-ascorbic acid to iron source was 0.056:1.

[0086] Test Example 1

[0087] The process curves of treating chromium-containing wastewater by Example 1, commercially purchased micron zero-valent iron material, and the material prepared in Comparative Examples 1-2 were drawn, as shown in FIG. Figure 7-8 shown.

[0088] Depend on Figure 7-8As can be seen, the materials used in Example 1 and Comparative Example 1 exhibit significantly superior degradation performance to the commercially available micron zero-valent iron material and the material in Comparative Example 2. In particular, within the first 20 minutes, the target pollutant Cr(VI) in Example 1 and Comparative Example 1 was rapidly degraded to near zero, demonstrating high reaction rates and efficiency. In contrast, the commercially available micron zero-valent iron material and the material in Comparative Example 2 achieved removal rates of only 10% and 60% within 20 minutes, respectively. This is attributed to the enhanced reactivity of the materials in Example 1 and Comparative Example 1 due to their modified properties. Furthermore, the pollutant concentration in Example 1 was lower than that in Comparative Example 1 at every time point, and complete pollutant removal was achieved in the shortest possible time (10 minutes). This demonstrates that Example 1 exhibits higher reactivity than Comparative Example 1 and, compared to Comparative Example 1, produces no harmful gases such as hydrogen sulfide, demonstrating the significant advantages of the present invention.

[0089] Test Example 2

[0090] The material in Example 1 was used to carry out a cycling experiment, with commercially available micronized zero-valent iron material used as a comparison. The specific operating steps were as follows:

[0091] 500 ml of the prepared acetic acid-sodium acetate buffer solution with a pH of 5 was transferred to a beaker, a chromium stock solution was added to bring the contaminant concentration to 5 mg / L, the mechanical stirring paddle was turned on, and 0.1 g of the modified new material (L-ZVI) in Example 1 was added to start the experiment. When the chromium contaminant in the solution was completely removed (within 10 min), Cr(VI) was repeatedly added to evaluate the reusability of L-ZVI. The experiment was stopped after 5 cycles (480 min).

[0092] A commercially available micronized zero-valent iron material (ZVI) was used as a comparison. The operation process was the same as that of the modified new material (L-ZVI) in Example 1, and the experiment was stopped at 480 minutes.

[0093] The comparison of the pollutant concentration change curves during the cycle experiment of this embodiment is as follows: Figure 9 As shown by Figure 9 It can be seen that L-ZVI in Example 1 performed 5 complete cycles within 480 minutes and still had a continuous removal ability, with strong reusability. In contrast, the commercially purchased micron zero-valent iron material only performed less than 3 cycles in the same time and had a slow reaction rate.

Claims

1. A method for preparing a micronized zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt, characterized in that the iron source of the material is micronized zero-valent iron, the modifier is L-ascorbic acid 2-phosphate sesquimagnesium salt, and the molar ratio of the iron source to the modifier is 1:(0.05-0.06); The steps are as follows: The zero-valent iron was pickled with acetic acid-sodium acetate buffer in an anaerobic environment to remove the passivation layer on the surface, and then L-ascorbic acid 2-phosphate sesquimagnesium salt solution was added and the reaction was shaken. The suspension after the reaction was filtered and freeze-dried to obtain the micron zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt.

2. The method for preparing the micronized zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt according to claim 1, characterized in that: The particle size of micron zero-valent iron particles is 70-80 μm.

3. The method for preparing the micronized zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt according to claim 1, characterized in that: The pH of acetic acid-sodium acetate buffer solution is 4, and the concentration is 0.2 mol / L.

4. The method for preparing the micronized zero-valent iron material modified by L-ascorbic acid 2-phosphate sesquimagnesium salt according to claim 1, characterized in that: In an oxygen-free environment, the micron zero-valent iron particles oscillate in a buffer solution to remove the passivation film for 10 minutes, the oscillation reaction time is 10 hours, and the temperature is 25°C.

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