Ball-milling mixed iron powder, its preparation method and application
By using a ball milling method to prepare mixed iron powder, the problem of passivation layer on the surface of zero-valent iron was solved, achieving self-driven depassivation, enhancing the reactivity and pollutant treatment capacity of zero-valent iron, and reducing preparation and use costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH
- Filing Date
- 2023-11-14
- Publication Date
- 2026-06-23
AI Technical Summary
The formation of a passivation layer on the surface of zero-valent iron reduces its reactivity. Existing methods are costly, require large equipment, are inconvenient to use, and pose potential environmental hazards, making it difficult to effectively overcome the passivation problem of zero-valent iron.
Zero-valent iron is mixed with iron compounds of other valence states and phenolic compounds using ball milling technology. Mixed iron powder is prepared by pre-oxidation ball milling, forming a mixture rich in dissolved ferrous iron and surface-adsorbed ferrous iron, thereby achieving self-driven depassivation and enhancing electron transfer and catalytic performance.
It achieves self-driven depassivation of zero-valent iron, improves the adsorption, reduction and co-precipitation capacity of pollutants, reduces costs, simplifies the preparation process, and maintains high-efficiency processing capacity at room temperature.
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Figure CN117483748B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water treatment, and particularly relates to a mixed iron powder with self-driven depassivation function, its preparation method and application. Background Technology
[0002] Zero-valent iron (ZVFe) has been widely used for treating various pollutants, including heavy metal removal, dehalogenation of halogenated organic compounds, and nitrate reduction, due to its advantages such as reducing activity, environmental friendliness, and low cost. However, upon contact with air and water, ZVFe forms natural iron (hydride) oxides on its surface. The formation of these oxides hinders the transfer of electrons from ZVFe to pollutants, leading to passivation. The formation of this passivation layer significantly reduces the reactivity of ZVFe, which is the biggest bottleneck restricting its application.
[0003] To overcome the problem of passivation on the surface of zero-valent iron, a series of methods have been developed to improve the reactivity of zero-valent iron. Nano-sizing gives zero-valent iron (ZVFe) extremely high specific surface area and activity, enabling it to treat various pollutants in water. However, the expensive reagents required for preparing nano-ZVFe limit its practical application. Adding suitable metals to form bimetallic systems with ZVFe can improve its pollutant treatment performance, but the metal elements required for synthesizing these systems pose potential environmental hazards. Physical methods such as ultrasonic assistance and weak magnetic field enhancement can improve the adsorption and reduction capabilities of ZVFe, but the required equipment and additional energy consumption limit their practical application. Acid washing of ZVFe before use effectively dissolves the surface passivation layer, which is the simplest method, but the passivation layer will reform when ZVFe is exposed to air or water again. Adding an appropriate amount of oxidant to the solution can promote the release of more ferrous ions from ZVFe, thereby improving its reduction capacity. However, the required oxidant must be a strong oxidant (such as hydrogen peroxide, potassium permanganate, sodium hypochlorite, etc.), which are either controlled substances or liquid reagents, making them unsuitable for transportation and storage, and posing certain risks during use.
[0004] In recent years, the use of ball milling technology to prepare mixed iron powder has shown many excellent properties. Ball milling and mixing zero-valent iron with other iron compounds (such as ferrous chloride, magnetite, and ferric disulfide) until homogeneous can improve electron transfer efficiency, enhance catalytic performance, and synergistically exert adsorption, reduction, and co-precipitation effects. Pre-oxidation, as a method to convert some zero-valent iron in situ into other iron compounds, can be used in conjunction with ball milling technology. Therefore, this patent uses a pre-oxidation ball milling method to prepare ordinary zero-valent iron into mixed iron powder. Experiments show that the surface of this iron powder is rich in two types of effective components: dissolved ferrous iron and surface-adsorbed ferrous iron. The dissolved ferrous iron undergoes hydrolysis to produce protons, and the surface-adsorbed ferrous iron combines with the protons, causing local acidity at the solid-liquid interface of the mixed iron powder. Under acidic conditions, the passivation layer dissolves and corrodes the zero-valent iron core, producing more dissolved ferrous iron and surface-adsorbed ferrous iron, forming a local acidity accumulation, and realizing a self-driven depassivation process. This not only effectively inhibits the passivation of zero-valent iron, but also accelerates the dissolution of zero-valent iron, thereby improving the degradation ability of pollutants. Summary of the Invention
[0005] The purpose of this invention is to address the passivation layer problem on the surface of zero-valent iron by providing a hybrid iron powder with self-driven depassivation function, its preparation method, and its application.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a ball-milled mixed iron powder (with self-driven depassivation function), wherein the ball-milled mixed iron powder is prepared by ball milling iron powder, a solid oxidant and a phenolic compound to obtain the ball-milled mixed iron powder; wherein the molar ratio of the iron powder, the solid oxidant and the phenolic compound is 160-200:10:0.5-1 (preferably 160:10:1).
[0008] Furthermore, the solid oxidant is one or a mixture of two or more of peroxymonosulfate, persulfate, and ferrate, preferably one or a mixture of two of peroxymonosulfate and persulfate, such as potassium peroxymonosulfate or sodium persulfate.
[0009] Furthermore, the phenolic compound is one or a mixture of two or more of phenol, 4-chlorophenol, and 2,4-dichlorophenol, preferably one or a mixture of two of 4-chlorophenol and 2,4-dichlorophenol, and most preferably 4-chlorophenol.
[0010] In one embodiment of the present invention, the ball-milled mixed iron powder contains iron primarily in the forms of zero-valent iron, dissolved ferrous iron, surface-adsorbed ferrous iron, and trivalent iron, accounting for 64%, 10%, 10%, and 16% of the total iron content, respectively. Furthermore, the mixed iron powder also contains trace amounts of sodium sulfate and graphite carbon. The mixed iron powder has a particle size range of 1-20 micrometers, is irregularly shaped polyhedral particles with a coral reef-like surface, and contains 57%, 13%, and 30% atomic percentages of iron, sulfur, and oxygen, respectively.
[0011] Preferably, the iron powder is reduced iron powder that has passed through a 100-mesh sieve.
[0012] Furthermore, the ball milling is performed using a vibratory ball mill, and the milling conditions are as follows: the grinding balls are zirconium dioxide, the ball-to-material ratio is 30-50:1 (preferably 30:1), the vibration frequency is 17-25.5 Hz (preferably 20.5 Hz), and the milling time is 2-6 hours (preferably 6 hours). In one embodiment of the present invention, the milling conditions are: a ball-to-material ratio of 30:1, a vibration frequency of 20.5 Hz, and a milling time of 6 hours. The milling atmosphere is air.
[0013] Secondly, the present invention provides an application of the above-mentioned ball-milled mixed iron powder in the treatment of pollutants, wherein the redox potential of the pollutants is higher than -447 millivolts.
[0014] Furthermore, the pollutant is one or a mixture of two of the following: organic compounds with oxidizing functional groups and heavy metal ions. Specifically, in embodiments of the present invention, the pollutant is nitrobenzene, nitrates, hexavalent chromium (such as when added in the form of dichromate), or trivalent chromium.
[0015] Specifically, the application involves adding the ball-milled mixed iron powder to a solution containing contaminants and stirring at room temperature.
[0016] Preferably, the pH of the contaminant-containing solution is 3.
[0017] Furthermore, the volume of the contaminant-containing solution is 2 L / g based on the mass of the ball-milled mixed iron powder.
[0018] In one embodiment of the present invention, the concentration of the contaminant in the contaminant-containing solution is 10-30 mg / L.
[0019] The application of the ball-milled mixed iron powder with self-driven depassivation function can enable rapid adsorption, reduction, and precipitation processes in solution to treat pollutants in wastewater.
[0020] Compared with the prior art, the beneficial effects of the present invention are:
[0021] (1) It can achieve self-driven depassivation, overcoming the passivation phenomenon caused by zero-valent iron in water. This composite iron powder is rich in iron components with multiple valence states. Among them, dissolved ferrous iron undergoes hydrolysis to produce protons, and surface-adsorbed ferrous iron combines with protons, making the solid-liquid interface of the mixed iron powder locally acidic. Under acidic conditions, the passivation layer dissolves and corrodes the zero-valent iron core, producing more dissolved ferrous iron and surface-adsorbed ferrous iron, forming a local acidity accumulation, and achieving the self-driven depassivation process. In addition, trivalent iron also undergoes hydrolysis in solution to produce protons. Protons can neutralize the alkalinity of water, buffering pH and inhibiting passivation.
[0022] (2) It possesses highly efficient reactivity, enabling rapid adsorption, reduction, and co-precipitation processes. The mixed iron powder exhibits adsorption and reduction activity in zero-valent iron, dissolved ferrous iron, and surface-adsorbed ferrous iron, while the ferric iron component also possesses adsorption and co-precipitation capabilities. All iron components work synergistically to rapidly treat pollutants in wastewater. Furthermore, the phenolic compounds in the raw materials are converted into quinones or graphite carbon structures during ball milling, providing channels for electron transport and accelerating the release of electrons from zero-valent iron, which is beneficial for pollutant degradation. Because 4-chlorophenol carries C-Cl bonds, which are more easily broken and coupled than CH bonds, this facilitates the formation of quinones or graphite carbon structures.
[0023] (3) Low cost, safe and simple preparation process, convenient use, and easy transportation and storage. It mainly uses reduced iron powder, with the addition of a small amount of solid oxidant and trace amounts of phenolic compounds. Dissolved ferrous iron and surface-adsorbed ferrous iron are generated in situ through the pre-oxidation method of solid oxidant. All raw materials are inexpensive and readily available. It is synthesized by a one-step method of vibratory ball milling, with no waste liquid or waste material generated. The material yield is high and the energy consumption requirement is low. It can be directly added to polluted water to treat pollutants. It can be stored in a normal temperature air environment. Even after passivation, it can be depassivated in water. The solid form is convenient for transportation and storage. Attached Figure Description
[0024] Figure 1 Scanning electron microscope image of the hybrid iron powder with self-driven depassivation function prepared in Example 1;
[0025] Figure 2 Scanning electron microscope image of a single hybrid iron powder with self-driven depassivation function prepared in Example 1;
[0026] Figure 3 The effect of the mixed iron powder prepared in Example 1 on the treatment of hexavalent chromium in wastewater;
[0027] Figure 4 The effect of the mixed iron powder prepared in Example 1 on the treatment of nitrobenzene in wastewater;
[0028] Figure 5Scanning electron microscope image of the single mixed iron powder with self-driven depassivation function prepared in Example 2;
[0029] Figure 6 The scanning electron microscope energy dispersive spectroscopy (SEM) analysis results of the hybrid iron powder with self-driven depassivation function prepared in Example 2;
[0030] Figure 7 X-ray diffraction pattern of the mixed iron powder prepared in Example 2;
[0031] Figure 8 The effect of the mixed iron powder prepared in Example 1 on the treatment of wastewater containing hexavalent chromium and nitrobenzene complex pollution;
[0032] Figure 9 The effect of the mixed iron powder prepared in Example 1 on the treatment of hexavalent chromium in wastewater with different pH ranges;
[0033] Figure 10 The effect of the mixed iron powder prepared in Example 1 on the treatment of nitrobenzene in wastewater with different pH ranges. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to the accompanying drawings and embodiments.
[0035] The iron powder used in the following examples is reduced iron powder that has passed through a 100-mesh sieve. Hexavalent chromium refers to potassium dichromate.
[0036] Example 1:
[0037] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0038] Step 1: Weigh out reduced iron powder, potassium persulfate, and 4-chlorophenol in a molar ratio of 160:10:1 to obtain 14 grams of mixed raw materials;
[0039] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours.
[0040] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0041] The mixed iron powder with self-driven depassivation function prepared in Example 1 was subjected to scanning electron microscopy (SEM) testing, and the SEM results are as follows: Figure 1 ,and Figure 2As shown. The mixed iron powder is in the form of irregular polyhedral particles with a coral reef-like surface and a particle size ranging from 1 to 20 micrometers. The iron species distribution of the mixed iron powder prepared in Example 1 was analyzed, and zero-valent iron, dissolved ferrous iron, surface-adsorbed ferrous iron, and trivalent iron accounted for 64%, 10%, 10%, and 16% of the total iron content, respectively.
[0042] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 1 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. A certain volume of the reaction solution was taken at regular intervals to determine the content of hexavalent and trivalent chromium. The results are as follows: Figure 3 As shown, the mixed iron powder can completely treat hexavalent chromium in wastewater within 15 minutes, rapidly reduce hexavalent chromium to trivalent chromium, and remove trivalent chromium through co-precipitation, demonstrating the high efficiency of the mixed iron powder in treating heavy metal wastewater.
[0043] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 1 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. A certain volume of the reaction solution was taken at regular intervals to determine the content of nitrobenzene and its degradation products. The results are as follows: Figure 4 As shown, the mixed iron powder can completely treat nitrobenzene in wastewater within 90 minutes and reduce nitrobenzene to aniline within 120 minutes, demonstrating the high efficiency of the mixed iron powder in degrading organic wastewater.
[0044] Example 2:
[0045] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0046] Step 1: Weigh reduced iron powder, sodium persulfate, and 4-chlorophenol according to a molar ratio of 160:10:1 to obtain 14 grams of mixed raw materials;
[0047] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours.
[0048] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0049] The mixed iron powder with self-driven depassivation function prepared in Example 2 was subjected to scanning electron microscopy (SEM) testing, and the SEM and energy dispersive spectroscopy (EDS) analysis results were obtained, as follows: Figure 5 and Figure 6 As shown, the mixed iron powder is in the form of irregular polyhedral particles with a coral reef-like surface and a particle size of approximately 20 micrometers. The atomic percentages of iron, sulfur, and oxygen are 57%, 13%, and 30%, respectively. X-ray diffraction testing was performed on the mixed iron powder with self-driven depassivation function prepared in Example 2, and the results are as follows... Figure 7 As shown. Figure 7 As shown, the mixed iron powder prepared in Example 2 is mainly composed of iron crystalline phase, with signal distribution at 44.7°, 65.0°, and 82.3°, and also contains a small amount of sodium sulfate crystalline phase.
[0050] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 2 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured. The results are shown in Table 1. The mixed iron powder can completely treat hexavalent chromium in wastewater within 15 minutes, demonstrating the high efficiency of the mixed iron powder in treating heavy metal wastewater.
[0051] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 2 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured. The results are shown in Table 1. The mixed iron powder was able to completely treat the nitrobenzene in the wastewater within 120 minutes, demonstrating the high efficiency of the mixed iron powder in treating organic wastewater.
[0052] Example 3:
[0053] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0054] Step 1: Weigh out reduced iron powder, potassium persulfate, and 4-chlorophenol according to a molar ratio of 200:10:1 to obtain 14 grams of mixed raw materials;
[0055] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material reach 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 4 hours.
[0056] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0057] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 3 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured. The results are shown in Table 1. The mixed iron powder could treat 97.5% of the hexavalent chromium within 15 minutes, demonstrating the high efficiency of the mixed iron powder in treating heavy metal wastewater.
[0058] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 3 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured. The results are shown in Table 1. The mixed iron powder was able to completely treat 95.9% of the nitrobenzene in the wastewater within 120 minutes, demonstrating the high efficiency of the mixed iron powder in treating organic wastewater.
[0059] Example 4:
[0060] Treatment of wastewater containing combined nitrobenzene and hexavalent chromium pollution: The treatment of the combined pollution was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 1 was completely poured into the Erlenmeyer flask, followed by 100 mL of wastewater containing 10 mg / L nitrobenzene and 20 mg / L hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. A certain volume of the reaction solution was taken at regular intervals to determine the content of nitrobenzene and hexavalent chromium. The results are as follows: Figure 8 As shown, the mixed iron powder can completely treat hexavalent chromium and nitrobenzene within 120 minutes, demonstrating the high efficiency of the mixed iron powder in treating complex polluted organic wastewater.
[0061] Example 5:
[0062] Mixed iron powder treatment of hexavalent chromium and nitrobenzene in wastewater with different pH values
[0063] Treatment of hexavalent chromium in wastewater with different pH values: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. Four portions of 0.05 g of the mixed iron powder prepared in Example 1 were completely poured into four Erlenmeyer flasks. Four portions of 100 mL hexavalent chromium wastewater containing 20 mg / L were then added. The pH of the hexavalent chromium aqueous solution was adjusted to 3, 5, 7, and 9 respectively using 0.01 M sulfuric acid or 0.01 M sodium hydroxide. After sealing the Erlenmeyer flasks with sealing film, they were placed in a shaker and reacted for 60 minutes at 25°C and 200 rpm. A certain volume of the reaction solution was taken at regular intervals to determine the hexavalent chromium content. The results are as follows: Figure 9 As shown, after 60 minutes of reaction, the removal rate of hexavalent chromium in wastewater with an initial pH of 3-9 reached over 85%, demonstrating that the mixed iron powder, due to its self-driven depassivation ability, can adapt to alkaline wastewater and maintain high reactivity over a wide pH range.
[0064] Treatment of nitrobenzene in wastewater with different pH values: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. Four portions of 0.05 g of the mixed iron powder prepared in Example 1 were completely poured into four Erlenmeyer flasks. Four portions of 100 mL of an aqueous solution containing 10 mg / L nitrobenzene were then added. The pH of the hexavalent chromium aqueous solution was adjusted to 3, 5, 7, and 9 respectively using 0.01 M sulfuric acid or 0.01 M sodium hydroxide. After sealing the Erlenmeyer flasks with sealing film, they were placed in a shaker and reacted for 120 minutes at 25°C and 200 rpm. A certain volume of the reaction solution was taken at regular intervals to determine the nitrobenzene content. The results are as follows: Figure 10 As shown, after 120 minutes of reaction, the removal rate of hexavalent chromium in wastewater with an initial pH of 3-9 reached over 95%, demonstrating that the mixed iron powder, due to its self-driven depassivation ability, can adapt to alkaline wastewater and maintain high reactivity over a wide pH range.
[0065] Example 6:
[0066] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0067] Step 1: Weigh reduced iron powder, potassium ferrate, and 4-chlorophenol according to a molar ratio of 160:10:1 to obtain 14 grams of mixed raw materials;
[0068] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours.
[0069] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0070] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 6 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured, and the results are shown in Table 1. The mixed iron powder could treat more than 90% of the hexavalent chromium in the wastewater within 15 minutes, demonstrating the high efficiency of mixed iron powder prepared with different types of solid oxidants in treating heavy metal wastewater. Since ferrates are unstable and easily decomposed, they can affect the effect of pre-oxidation ball milling. Therefore, persulfate is preferred in this invention.
[0071] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 6 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured, and the results are shown in Table 1. The mixed iron powder was able to treat 88.1% of the nitrobenzene in the wastewater within 120 minutes, demonstrating the high efficiency of mixed iron powder prepared with different types of solid oxidants in treating organic wastewater. Since ferrates are inherently unstable and easily decompose, they can affect the effect of pre-oxidation ball milling. Therefore, persulfate is preferred in this invention.
[0072] Example 7:
[0073] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0074] Step 1: Weigh reduced iron powder, potassium persulfate, and 2,4-dichlorophenol according to a molar ratio of 160:10:1 to obtain 14 grams of mixed raw materials;
[0075] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours.
[0076] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0077] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 7 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured, and the results were as follows: Figure 10As shown, the mixed iron powder can completely treat hexavalent chromium in wastewater within 15 minutes, indicating that different solid aromatic compounds can form structures that are conducive to electron transport during ball milling, thus promoting the efficient treatment capacity of mixed iron powder for heavy metal wastewater.
[0078] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 7 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured, and the results are shown in Table 1. The mixed iron powder could completely treat the nitrobenzene in the wastewater within 120 minutes, demonstrating the high efficiency of the mixed iron powder in degrading organic wastewater. This indicates that different solid aromatic compounds can form structures conducive to electron transport during ball milling, promoting the high efficiency of the mixed iron powder in treating organic wastewater.
[0079] Example 8: Halogen-free aromatic compounds
[0080] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0081] Step 1: Weigh out reduced iron powder, potassium persulfate, and phenol according to a molar ratio of 160:10:1 to obtain 14 grams of mixed raw materials;
[0082] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1 to make the mass ratio of zirconia balls to mixed raw material 30:1, and put it into a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours.
[0083] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0084] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Comparative Example 8 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured. The results are shown in Table 1. The mixed iron powder could treat 92.3% of the hexavalent chromium in the wastewater within 15 minutes, indicating that different solid aromatic compounds can form structures conducive to electron transport during ball milling, promoting the efficient treatment capacity of the mixed iron powder for heavy metal wastewater. When the aromatic compounds contain halogen atoms, they can further treat the hexavalent chromium wastewater.
[0085] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the prepared mixed iron powder was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured. The results are shown in Table 1. The mixed iron powder was able to treat 87.6% of the nitrobenzene in the wastewater within 120 minutes, demonstrating the high efficiency of the mixed iron powder in treating organic wastewater. This indicates that different solid aromatic compounds can form structures conducive to electron transport during ball milling, promoting the high efficiency of the mixed iron powder in removing heavy metal wastewater. When the aromatic compounds contain halogen atoms, they can further treat organic wastewater.
[0086] Example 9: Aromatic compounds
[0087] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0088] Step 1: Weigh reduced iron powder and potassium persulfate in a molar ratio of 16:1 to obtain 14 grams of mixed raw materials;
[0089] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1, and place it in a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours;
[0090] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0091] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Comparative Example 9 was completely poured into a 250 mL Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured, and the results are shown in Table 1. No solid aromatic compounds were added during the ball milling process, and the prepared iron powder did not have a fast electron transport channel. The mixed iron powder could treat 80.7% of the hexavalent chromium in the wastewater within 15 minutes, indicating that the structure formed by the aromatic compounds during the preparation process can further improve the reducing power of the mixed iron powder.
[0092] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the prepared mixed iron powder was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the content of nitrobenzene and its degradation products was measured. The results are shown in Table 1. No solid aromatic compounds were added during the ball milling process, and the prepared iron powder did not have a fast electron transport channel. The mixed iron powder could treat 77.7% of the nitrobenzene in the wastewater within 120 minutes, indicating that the structure formed by the aromatic compounds during the preparation process can further improve the reducing power of the mixed iron powder.
[0093] Example 10:
[0094] Preparation method and application of a hybrid iron powder with self-driven depassivation function
[0095] Step 1: Weigh out reduced iron powder, potassium persulfate, and 4-chlorophenol according to a molar ratio of 160:10:0.5 to obtain 14 grams of mixed raw materials;
[0096] Step 2: Add 75 6 mm and 75 8 mm zirconia balls to the mixed raw material obtained in Step 1, and place it in a vibratory ball mill and run it at a frequency of 20.5 Hz for 6 hours;
[0097] Step 3: Separate the zirconium oxide balls and iron powder using a standard sieve to obtain a mixed iron powder with self-driven depassivation function.
[0098] Treatment of hexavalent chromium in wastewater: The treatment of hexavalent chromium was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 10 was completely poured into a 250 mL Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 20 mg / L of hexavalent chromium. The flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 15 minutes. After the reaction, the hexavalent chromium content was measured. The results are shown in Table 1. The addition of insufficient solid aromatic compounds during ball milling resulted in a small number of rapid electron transfer channels in the prepared iron powder. The mixed iron powder could treat 94.6% of the hexavalent chromium in the wastewater within 15 minutes, indicating that the structure formed by the aromatic compounds during the preparation process can further improve the reducing power of the mixed iron powder.
[0099] Treatment of nitrobenzene in wastewater: The treatment of nitrobenzene was carried out in an Erlenmeyer flask. 0.05 g of the mixed iron powder prepared in Example 10 was completely poured into the Erlenmeyer flask, followed by 100 mL of an aqueous solution containing 10 mg / L of nitrobenzene. The Erlenmeyer flask was sealed with sealing film and placed in a shaker. The reaction was carried out at 25°C and 200 rpm for 120 minutes. After the reaction, the nitrobenzene content was measured, and the results are shown in Table 1. The addition of insufficient solid aromatic compounds during ball milling resulted in a small number of rapid electron transfer channels in the prepared iron powder. The mixed iron powder was able to treat 89.4% of the nitrobenzene in the wastewater within 120 minutes, indicating that the structure formed by the aromatic compounds during the preparation process can further improve the reducing power of the mixed iron powder.
[0100] Table 1. Treatment effects of mixed iron powder prepared in different embodiments on hexavalent chromium and nitrobenzene in wastewater;
[0101]
[0102]
Claims
1. A ball-milled mixed iron powder, characterized in that... The ball-milled mixed iron powder is prepared by the following method: iron powder, solid oxidant, and phenolic compound are mixed and ball-milled to obtain the ball-milled mixed iron powder; the molar ratio of iron powder, solid oxidant, and phenolic compound is 160-200. 10：0 .5-1； Phenolic compounds are one or a mixture of two of 4-chlorophenol and 2,4-dichlorophenol.
2. The ball-milled mixed iron powder as described in claim 1, characterized in that: The molar ratio of the iron powder, solid oxidant, and phenolic compound is 160:10:
1.
3. The ball-milled mixed iron powder as described in claim 1, characterized in that: The solid oxidant is one or a mixture of two or more of persulfate, persulfate, and ferrate.
4. The ball-milled mixed iron powder as described in claim 1, characterized in that: The ball milling is carried out using a vibratory ball mill. The ball milling conditions are as follows: the grinding balls are zirconium dioxide, the ball-to-material ratio is 30-50:1, the vibration frequency is 17-25.5 Hz, and the ball milling time is 2-6 hours.
5. The application of ball-milled mixed iron powder as described in claim 1 in the treatment of pollutants, wherein the redox potential of the pollutants is higher than -447 mV.
6. The application as described in claim 5, characterized in that: The pollutants are one or a mixture of two of the following: organic compounds with oxidizing functional groups and heavy metal ions.
7. The application as described in claim 5, characterized in that... The application involves adding the ball-milled mixed iron powder to a solution containing contaminants and stirring at room temperature.
8. The application as described in claim 7, characterized in that: The pH of the contaminated solution is 3; the volume of the contaminated solution, based on the mass of the ball-milled mixed iron powder, is 2 L / g.