A method for modifying siderite, modified siderite composite material and application

Abstract

The application discloses a modification method of siderite, a modified siderite composite material and application, and the modification method comprises the following steps: grinding, screening, mixing and ball milling of zero-valent iron, phosphate rock powder and siderite to prepare the modified siderite composite material. The phosphate rock powder is used to corrode the siderite to release ferrous iron, and the synergistic effect of the iron powder is added, so that slow release and regeneration of Fe(II) are realized, and the stability of the material is enhanced. In the remediation of organic contaminated soil, the modified siderite composite material activates persulfate to generate strong oxidizing free radicals by slow release of active Fe(II), so that rapid degradation of dichlorophenol and other organic pollutants is realized. The material has the advantages of high soil organic pollution degradation efficiency, environmental friendliness, low cost, good stability and strong adaptability.

Description

Technical Field

[0001] This invention belongs to the technical field of organic polluted soil remediation materials, specifically relating to a method for modifying siderite, modified siderite composite materials, and their applications. Background Technology

[0002] With the continuous advancement of industrialization and modernization, environmental pollution has become a global concern. Soil, as a crucial component of the ecosystem, supports human production and daily life activities, but it is also a significant carrier of various pollutants. Among these, soil organic pollutant pollution is particularly prominent. These pollutants include organic matter from sources such as industrial wastewater, pesticides, and oil spills, such as dichlorophenol. They not only affect soil quality and ecosystem stability but may also enter the human body through the food chain, posing a serious threat to human health.

[0003] Traditional methods for treating soil organic pollutants mainly include physical, chemical, and biological methods. Physical methods, such as adsorption and extraction, are simple to operate but costly and cannot completely remove pollutants. Chemical methods, such as oxidation and reduction, while highly efficient, are prone to secondary pollution and may damage soil structure and properties. Biological methods, such as microbial degradation, are environmentally friendly but time-consuming and highly susceptible to environmental factors. Therefore, finding an efficient, environmentally friendly, and economical technology for degrading soil organic pollutants has become an important research direction in the field of environmental science.

[0004] In recent years, the technology of catalytic activation of persulfate based on siderite materials to degrade organic pollutants has attracted widespread attention. This technology utilizes ferrous ions (Fe(II)) in siderite materials to activate persulfate and generate sulfate radicals (SO42-). -· Sulfate radicals possess strong oxidizing properties and can effectively degrade organic pollutants. Compared with traditional methods, this method has advantages such as fast reaction speed, high degradation efficiency, and environmental friendliness, thus showing broad application prospects in the field of soil organic pollutant remediation.

[0005] However, siderite materials face several challenges in degrading organic pollutants. First, Fe(II) is easily oxidized to ferric ions (Fe(III)), leading to reduced degradation efficiency. Second, siderite materials exhibit poor regeneration properties, failing to continuously provide sufficient ferrous ions. Finally, the poor dispersibility and stability of siderite materials in soil negatively impact their degradation effectiveness. Therefore, developing a modified siderite material to improve its efficiency and stability in activating persulfate degradation of soil organic pollutants is of significant practical importance and application value. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for modifying siderite, a modified siderite composite material, and its applications. The material is prepared by ball milling of siderite (Sd), phosphate rock powder (PR), and reduced iron powder (ZVI), aiming to improve the efficiency and stability of siderite in the degradation and remediation of organic pollutants in soil and water bodies through modification.

[0007] The principles of the siderite modification method, modified siderite composite materials, and their applications in this invention are mainly based on the following aspects: the redox properties of siderite, as a relatively stable source of Fe(II), can catalyze the generation of highly oxidizing free radicals (such as sulfate free radicals SO4) from persulfate. -· These free radicals can oxidize and degrade organic pollutants. The activation effect of phosphate rock powder, the PO4 in the phosphate rock powder... 3- It can react with the oxide layer (mainly iron oxides and hydroxides) on the surface of siderite, thereby destroying these oxide layers and exposing more active Fe(II) surfaces. The synergistic effect of zero-valent iron: The addition of zero-valent iron not only loosens the structure of siderite through mechanical force, exposing more active surfaces, but also, during ball milling, zero-valent iron may be oxidized into iron compounds of different valence states (such as Fe(II) or Fe(III) compounds). These iron compounds introduce new active sites on the siderite surface, forming complexes with siderite and phosphate rock. The formation of these complexes further enhances the stability and reactivity of the material. The oxidative degradation effect of free radicals: When the modified siderite composite material is mixed with persulfate, the Fe(II) on the modified siderite surface can activate the persulfate, producing SO4. -· It rapidly oxidizes and degrades organic pollutants. It possesses self-regenerating properties; during the reaction, Fe(II) on the surface of the siderite is oxidized to Fe(III), forming an oxide layer. However, due to the presence of PO4 in the phosphate rock powder... 3- The presence of these oxide layers allows them to be corroded, re-exposing Fe(II) and enabling the material to self-regenerate. This self-regenerative property ensures the stability and effectiveness of the modified siderite composite material over a long period of time.

[0008] The present invention adopts the following technical solution:

[0009] A method for modifying siderite, the method comprising the following steps:

[0010] (1) Mix reduced iron powder, phosphate rock powder and siderite in the mass ratio;

[0011] (2) Add the mixed material and grinding balls together to the ball mill jar for ball milling.

[0012] In the modification method described above, the mass ratio of reducing iron powder, phosphate rock powder, and siderite is 1-3:1-3:1-3; preferably 1:3:1.

[0013] Step (1) The reduced iron powder, phosphate rock powder and siderite are passed through a 100-mesh sieve and then mixed.

[0014] The reducing iron powder is iron powder or industrial iron filings.

[0015] In step (2), the mass ratio of grinding balls to the mixture is 10:1 to 20:1, preferably 15:1.

[0016] Step (2) The rotation speed of the ball mill is 200-400 rpm, preferably 360 rpm. More preferably, the mill is set to reverse once every 30 minutes to ensure that the sum of the clockwise milling time is equal to the sum of the counterclockwise milling time. The milling time is 1-4 hours. The preferred milling time is 2 hours.

[0017] The present invention also provides a modified siderite composite material obtained by the above method.

[0018] The present invention also provides the application of the modified siderite composite material in activating persulfate degradation of organic pollutants.

[0019] The organic pollutants mentioned include dichlorophenol.

[0020] Treatment targets containing organic pollutants include water bodies and soil.

[0021] The application of the modified siderite composite material provided by this invention in activating persulfate degradation of soil organic pollutants includes:

[0022] Oxidative degradation of dichlorophenol solution: By adding appropriate amounts of modified siderite composite material and persulfate, and adjusting the dosage of different materials, the concentration of persulfate and the pH, dichlorophenol in the solution can be effectively degraded.

[0023] Degradation of dichlorophenol contaminated soil: Adding modified siderite composite material and sodium persulfate to contaminated soil, and adjusting parameters such as the amount of material added, the amount of sodium persulfate added, and the water-soil ratio can significantly improve the removal rate of dichlorophenol and improve soil indicators such as available phosphorus, available nitrogen, organic matter, and microorganisms.

[0024] In summary, this invention provides a method for preparing a modified siderite composite material (ZVI / PR / Sd) and its application in the degradation and remediation of organic pollutants in soil and water. This material not only has high degradation capacity but also good stability and environmental friendliness, providing a low-cost and high-efficiency method for the treatment of soil and water pollutants.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The modified siderite composite material of this invention has strong self-regeneration properties, and the PO4 in phosphate rock... 3- It can continuously corrode the surface of siderite, thereby releasing more active Fe(II) and achieving self-regeneration of the material.

[0027] 2. The modified siderite composite material of the present invention has high degradation efficiency for organic pollutants in soil, and the active Fe(II) can effectively activate persulfate to produce SO4. -· This allows for the efficient degradation of organic pollutants.

[0028] 3. The modified siderite composite material of the present invention has good stability. The synergistic effect of phosphate rock and zero-valent iron improves the stability and dispersibility of the material, enabling it to function better in soil and water. Attached Figure Description

[0029] Figure 1 Here are the SEM and EDX images of the modified composite material of this invention;

[0030] Figure 2 SEM images of raw materials: reduced iron powder (a), phosphate rock (b), and siderite (c);

[0031] Figure 3 Here is the XRD pattern of the modified composite material of this invention;

[0032] Figure 4 The effect of different mass ratios on Fe(II) release;

[0033] Figure 5 Comparison of Fe(II) release from siderite material, comparative material, and the modified composite material of this invention.

[0034] Figure 6 The effect of different ball milling times on Fe(II) release;

[0035] Figure 7 The effect of different addition amounts on Fe(II) release;

[0036] Figure 8 The effect of different pH values ​​on Fe(II) release;

[0037] Figure 9 The removal of dichlorophenol by different material dosages;

[0038] Figure 10 The removal of dichlorophenol by different oxidant concentrations;

[0039] Figure 11 The removal of dichlorophenol at different pH values;

[0040] Figure 12The effect of feed ratio on Fe(II) release from soil;

[0041] Figure 13 To investigate the effects of different feed ratios on the removal of dichlorophenol from soil;

[0042] Figure 14 The effect of persulfate dosage on Fe(II) release in soil;

[0043] Figure 15 The effects of different persulfate dosages on the removal of dichlorophenol from soil;

[0044] Figure 16 The effect of soil-water ratio on Fe(II) release from soil;

[0045] Figure 17 To investigate the effects of different water-to-soil ratios on the removal of dichlorophenol from soil;

[0046] Figure 18 The bar chart shows the species composition at the genus level before and after soil oxidation and degradation, as well as the collinearity diagram. Detailed Implementation

[0047] The technical solution of the present invention will be further illustrated below through specific embodiments, but not to limit the scope of protection of the claims of the present invention.

[0048] Example 1

[0049] The modified composite material was prepared by ball milling a mixture of reduced iron powder, phosphate rock, and siderite. An omnidirectional planetary ball mill was used as the experimental equipment. Before material preparation, 5g of reduced iron powder, phosphate rock powder, and siderite were weighed in a mass ratio of 1:3:1. This mixture was then added to a grinding jar along with 75g of agate balls with a ball-to-material ratio of 15:1. After placing the grinding jar in the ball mill, the mill parameters were set as follows: rotation speed 360 rpm, reverse rotation every 30 minutes, with the sum of clockwise and counterclockwise grinding times equal. After 2 hours of grinding, the modified composite material was obtained. The morphology, structure, and elemental composition of the modified composite material are as follows. Figure 1 As shown by scanning electron microscopy (SEM) and EDX, the material contains the elements C, O, S, P, Ca, and Fe. The O content of the ball-milled material is lower than that of the original phosphate rock powder and siderite, and the ball milling process promotes the release of phosphate rock powder. It has a corrosive effect on the surface of siderite, and the iron and phosphorus elements are relatively evenly distributed inside the material. Figure 2 The SEM image of the raw material clearly shows that the surface of the siderite raw material is relatively smooth. However, as shown in the image... Figure 1As shown, the surface structure of the material has undergone significant changes after careful modification. The originally smooth surface has now been transformed into a rough and uneven surface. This change not only significantly increases the specific surface area of ​​siderite, but also effectively increases its active sites.

[0050] Example 2

[0051] The modified composite material was prepared by ball milling a mixture of reduced iron powder, phosphate rock, and siderite. An omnidirectional planetary ball mill was used as the experimental equipment. Before material preparation, 5g of a total of reduced iron powder, phosphate rock powder, and siderite (in mass ratios of 1:1:3, 1:2:2, 1:3:1, 2:1:2, 2:2:1, and 3:1:1, respectively) and 75g of agate balls with a ball-to-material ratio of 15:1 were weighed and added to the ball mill jar. After placing the ball mill jar in the ball mill, the mill parameters were set as follows: rotation speed 360 rpm, reverse rotation every 30 minutes, with the sum of clockwise and counterclockwise milling times equal to the sum of counterclockwise milling times. After 2 hours of milling, the modified composite material was obtained. Figure 3 The XRD patterns of the raw materials and the modified composite materials prepared under different mass ratios are shown. As the proportion of siderite increases, the diffraction peaks of siderite become increasingly prominent. During ball milling, mechanical stress and energy cause the formation of amorphous substances, resulting in the inability to detect obvious diffraction peaks by XRD. This composite material may exist in an amorphous or low-crystallinity form within the siderite surface film, exhibiting an irregular structure, high specific surface area, and high chemical activity, which can enhance the catalytic activity of siderite.

[0052] The Fe(II) release of ZVI / PR / Sd prepared with different mass ratios (ZVI / PR / Sd = 1:3:1, 1:2:2, 1:3:1, 2:1:2, 2:2:1, 3:1:1) was tested. 0.1 g of the ball-milled material was dissolved in 100 mL of water with pH = 4.15, and the ferrous ion concentration was measured at 30 min, 2 h, and 24 h. Figure 4As shown, after 30 minutes of reaction, the ZVI / PR / Sd = 1:1:3 material released 0.9 mg / L of ferrous iron. Materials with ZVI / PR / Sd = 1:3:1, 2:2:1, and 3:1:1 released more ferrous iron (2 mg / L, 2.28 mg / L, and 2.46 mg / L, respectively). After 2 hours of reaction, the ZVI / PR / Sd = 1:1:3 material released 0.8 mg / L of ferrous iron. Materials with ZVI / PR / Sd = 1:3:1, 2:2:1, and 3:1:1 released more ferrous iron (2.9 mg / L, 2.78 mg / L, and 1.92 mg / L, respectively), and the release was higher than after 30 minutes. After 24 hours of reaction, the ZVI / PR / Sd = 1:3:1 material released more ferrous iron, but less than the amount released after 2 hours. Phosphate ions in phosphate rock powder can corrode and activate siderite. During the modification process, iron powder and phosphate ions work together to promote the reduction reaction of iron in siderite. This synergistic effect further increases the release of Fe(II) in siderite, making the modification effect of siderite more significant. The best overall effect is determined when the mass ratio is 1:3:1.

[0053] Comparative Example 1

[0054] Phosphate rock and siderite were mixed and prepared by ball milling. An omnidirectional planetary ball mill was used as the experimental equipment. Before material preparation, 5g of phosphate rock and siderite were weighed in a 3:1 mass ratio and added to a grinding jar along with 75g of agate balls (15:1 ball-to-material ratio). After placing the grinding jar in the ball mill, the mill parameters were set to: 360 rpm, with a reverse rotation performed every 30 minutes of milling, the sum of clockwise milling times equaling the sum of counterclockwise milling times. After 2 hours of milling, the control material was obtained. 0.1g each of the raw material siderite, the control material (Comparative Example 1), and the modified composite material prepared in Example 1 were dissolved in 100mL of water with pH = 4.15, and the ferrous ion concentration was measured at 30min, 2h, and 24h, respectively. Figure 5 It can be seen that the original siderite material and the comparative material both exhibited low levels of Fe(II) release. However, the modified composite material prepared in Example 1 showed a significant advantage in Fe(II) release performance. During the modification process, siderite, as the core component, underwent significant structural changes under the combined mechanical and chemical effects of phosphate rock and reduced iron powder. The addition of phosphate rock powder may have activated siderite through phosphate ion corrosion, promoting its decomposition and Fe(II) release; the reduced iron powder, by providing a reducing environment, promoted the conversion of iron in siderite from high to low valence states, thereby increasing the Fe(II) release.

[0055] Example 3

[0056] The modified composite material was prepared by ball milling a mixture of reduced iron powder, phosphate rock, and siderite. The experimental equipment used was an omnidirectional planetary ball mill. Before material preparation, 5g of reduced iron powder, phosphate rock powder, and siderite were weighed in a mass ratio of 1:3:1 and added to a ball mill jar along with 75g of agate balls with a ball-to-material ratio of 15:1. After placing the ball mill jar in the mill, the mill parameters were set to: a rotation speed of 360 rpm, and a reverse rotation every 30 minutes of milling, with the sum of clockwise and counterclockwise milling times equal. The modified composite material was obtained after milling for 1 hour, 2 hours, 3 hours, and 4 hours. 0.1g of each material was dissolved in 100mL of water with pH = 4.15. Samples were taken at 30 minutes, 2 hours, and 24 hours of reaction for measurement. The amount of Fe(II) released from the materials prepared at different milling times was as follows: Figure 6 The highest ferrous iron release was observed after 2 hours of ball milling. During ball milling, mechanical energy is converted into internal energy, increasing the reactivity of the composite material. However, excessively long milling times may cause smaller particles to re-agglomerate and clump together, reducing the number of active sites and hindering the regeneration of active centers. Simultaneously, the active PO4... 3- Fe(II) will also combine during excessively long ball milling processes, preventing the formation of more ferrous iron. Considering the amount of Fe(II) produced and the economy and efficiency of material preparation, a ball milling time of 2 hours was determined to be the optimal condition.

[0057] Example 4

[0058] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 1. 0.1g to 0.4g of the ball-milled material was dissolved in 100mL of water with pH = 4.15, and the ferrous ion concentration was measured at 30min, 2h, and 24h. Figure 7 It can be seen that as the amount added increases, the amount of Fe(II) released also increases. Considering both efficiency and economy, adding 0.3g yields the best overall effect.

[0059] Example 5

[0060] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 1. 0.3 g of the ball-milled material was dissolved in 100 mL of water with a pH of 1-6 (the pH was adjusted using 0.1 M HCl and 0.1 M NaOH). The ferrous ion concentration was measured at 30 min, 2 h, and 24 h. Figure 8 It can be seen that when the pH is less than 3, a large amount of Fe(II) is released from the system; when the pH is equal to or greater than 3, the amount of Fe(II) released decreases significantly; and when the pH is greater than 3, the amount of Fe(II) released tends to stabilize with no significant change. Furthermore, the amount of Fe(II) released tends to stabilize with increasing time.

[0061] Example 6

[0062] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 1. A 100 mL solution containing 20 mg / L of 2,4-dichlorophenol was prepared. The initial solution pH was ~7.0. After adding 2 mM sodium persulfate, the solution was shaken on a shaker. 0, 0.1, 0.2, 0.3, and 0.4 g of the composite material were weighed and added to the above solution to initiate the reaction. At given time intervals, 2 mL of the suspension was drawn, filtered through a 0.45 μm microporous membrane, and 1 mL of sample was added. 0.5 mL of methanol was added to quench free radicals, and the sample was then placed in a liquid chromatography vial. The concentration change of 2,4-dichlorophenol was determined using liquid chromatography. Figure 9 As shown, the dosage of the material increased from 0g to 0.4g, and the dosage had a significant impact on the removal of dichlorophenol. When the dosage of the material was 0.3g, 39.35% of dichlorophenol could be removed within 1 hour; when the dosage of the material was 0.3g, the removal rate of dichlorophenol could reach 49.63% within 2 hours.

[0063] Example 7

[0064] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 6 (the initial pH was not adjusted). The difference is that 0, 1, 2, 3, and 4 mM sodium persulfate were added respectively, and 0.3 g of the composite material was added to initiate the reaction. The change in the concentration of 2,4-dichlorophenol was measured. Figure 10 It can be seen that the addition of different doses of sodium persulfate has a significant impact on the removal efficiency of dichlorophenol. When 2 mM sodium persulfate is added, the removal efficiency of dichlorophenol reaches 71% after 2 hours. When the amount of sodium persulfate is increased to 4 mM, the removal efficiency of dichlorophenol is close to 100% after 2 hours. When the amount of oxidant in the system reaches a certain level, the degradation efficiency of dichlorophenol is sufficient to reach 100%. However, if the amount of oxidant in the system is too large, the degradation efficiency of dichlorophenol may be reduced. This is because when the amount of organic matter is fixed, the large number of free radicals generated by excessive oxidant will lead to self-quenching.

[0065] Example 8

[0066] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 6, except that 0.3g of the composite material is added to initiate the reaction, the initial pH of the reaction system is adjusted to 3-9, and the change in the concentration of 2,4-dichlorophenol is measured. Figure 11 As shown, under initial pH conditions of 3.0-9.0, rapid removal of dichlorophenol can be observed under relatively acidic conditions. At pH=3, the removal rate reaches 97.37% within 1 hour; at pH=5, the removal rate reaches 99.09% within 2 hours. At pH=7, 76.66% is removed after 4 hours. Under alkaline conditions, the removal efficiency is slower, with 53.31% removed after 4 hours. Increased pH easily leads to the reaction of Fe and OH-. -The reduced release of Fe(II) decreases the activation of persulfate, leading to fewer free radicals and thus less free radical oxidative degradation of organic matter, resulting in lower removal efficiency. During the oxidative degradation process, the decomposition of sodium persulfate releases a large amount of H₂. + This also allows the system to have a wider range of applicable pH values.

[0067] Example 9

[0068] The raw materials and reaction conditions for preparing the material in this embodiment are the same as in Example 1 (with the addition of 10 mM sodium persulfate). Six portions of 2 g of prepared contaminated soil (dichlorophenol concentration of 200 mg / kg) were weighed into centrifuge tubes. The material was added to the centrifuge tubes at feed ratios of 1%, 3%, and 5% (material to soil mass ratio), and stirred thoroughly with a glass rod. Deionized water was then added at a 1:1 water-to-soil ratio. The experiment was repeated twice to ensure the accuracy of the experimental data. After a certain reaction time, samples were taken to measure the Fe(II) release and dichlorophenol concentration. Figure 12 It can be seen that at 2 hours, the Fe(II) release from the 1% and 3% feed ratios was significantly less than that from the 5% feed ratio. From 2 hours to 6 hours, Fe(II) was released rapidly and in large quantities. From 6 hours onwards, the Fe(II) release tended to stabilize with increasing time. The Fe(II) release from the 3% and 5% feed ratios was very similar from 6 hours onwards. Figure 13 It can be seen that adding 1% ZVI / PR / Sd dichlorophenol to the system can achieve a removal rate of 74.55% after 72 hours, adding 3% ZVI / PR / Sd dichlorophenol can achieve a removal rate of 80.05% after 72 hours, and adding 5% ZVI / PR / Sd dichlorophenol can achieve a removal rate of 84.59% after 72 hours. At the same time, the removal rate increases continuously with the increase of material dosage, and the removal efficiency continues to increase with the extension of treatment time.

[0069] Example 10

[0070] The raw materials and reaction conditions for preparing the materials in this embodiment are the same as in Example 1. Ten portions of 2g each of the prepared contaminated soil (dichlorophenol concentration 200mg / kg) were weighed into centrifuge tubes. The materials were added to the soil sample at a feed ratio of 3%, and stirred thoroughly. Deionized water was added in a 1:1 ratio. Finally, 4mM, 6mM, 10mM, 12mM, and 15mM sodium persulfate were added to the centrifuge tubes respectively, and the mixture was stirred again and shaken to react. Samples were taken for analysis after a certain reaction time. Figure 14 It can be seen that at 2 hours, the Fe(II) release from 4 mM persulfate was significantly less than that from the others. From 6 hours onwards, the Fe(II) release tended to stabilize with increasing time, and the Fe(II) release amounts were very similar from 6 hours onwards. Figure 15As can be seen, the removal rate of dichlorophenol increases with the increase of sodium persulfate concentration from 4 mM to 15 mM. When the sodium persulfate concentration is 4 mM, the removal rate is 64.93% after 72 hours; when the sodium persulfate concentration is 6 mM, the removal rate is 73.39% after 72 hours; when the sodium persulfate concentration is 10 mM, the removal rate is 80.78% after 72 hours; when the concentration is 12 mM, the removal rate is 83.71% after 72 hours; and when the concentration is 15 mM, the removal rate is 84.48% after 72 hours.

[0071] Example 11

[0072] The raw materials and reaction conditions for preparing the materials in this embodiment are the same as in Example 1. Eight portions of the prepared contaminated soil (2g each) were weighed into centrifuge tubes, and the materials were added at a feed ratio of 3%. After stirring evenly, deionized water was added at water-to-soil ratios of 1:2, 1:1, 2:1, and 3:1, respectively. Finally, 10mM sodium persulfate was added to each, and the mixture was stirred and shaken for a certain period of time before sampling and determination. The method was the same as above. Figure 16 It can be seen that at 2 hours, the Fe(II) release amounts of 2:1 and 3:1 ratios were significantly less than those of others. From 6 hours onwards, the Fe(II) release amounts tended to stabilize with increasing time, and from 6 hours onwards, the Fe(II) release amounts were very similar. Figure 17 As shown, increasing the water-to-soil ratio from 1:1 to 2:1 significantly affects the removal efficiency of dichlorophenol. When the water-to-soil ratio is 1:2, the removal rate of dichlorophenol after 72 hours is 58.51%. With increasing water-to-soil ratio, the removal efficiency of dichlorophenol also increases, reaching 80.54% after 72 hours when the ratio increases to 2:1. This significant difference may be due to the uneven mixing of water and soil when the water-to-soil ratio is reduced, preventing the oxidant from fully contacting the pollutants in the soil. Increasing the water content can correspondingly increase the degradation rate of dichlorophenol, but it also increases the cost of subsequent wastewater treatment.

[0073] Example 12

[0074] The raw materials and reaction conditions for preparing the materials in this embodiment are the same as in Example 9, the difference being that the materials are added to the reaction system at a feed ratio of 3%. After a certain reaction time, samples were taken to determine the abundance of soil microorganisms before and after the reaction. High-throughput sequencing was used to analyze the microbial diversity of the acclimatized soil, and the abundance of major microorganisms was as follows: Figure 18As shown, norank-Caulobacteraceae (58.32%), Ralstonia (30.71%), and Chitinophaga (8.84%) were found in the soil before the reaction, while norank-Caulobacteraceae (55.44%), Ralstonia (30.24%), Chitinophaga (9.39%), and Burkholderia-Caballeronia-Paraburkholderia (2.12%) were found in the soil after dichlorophenol oxidation degradation. This result indicates that soil remediation treatment has a relatively small impact on microbial community diversity.

Claims

1. A method for modifying siderite, characterized in that, The method includes the following steps: (1) Mix the reducing iron powder, phosphate rock powder and siderite in the mass ratio; (2) Add the mixed material and grinding balls together into the ball mill jar for ball milling; The mass ratio of reduced iron powder, phosphate rock powder and siderite is 1-3:1-3:1-3.

2. The modification method according to claim 1, characterized in that, The mass ratio of reduced iron powder, phosphate rock powder and siderite is 1:3:

1.

3. The modification method according to claim 1, characterized in that, Step (1) The reduced iron powder, phosphate rock powder and siderite are passed through a 100-mesh sieve and then mixed.

4. The modification method according to claim 1, characterized in that, The reducing iron powder is industrial iron filings.

5. The modification method according to claim 1, characterized in that, In step (2), the mass ratio of grinding balls to the mixture is 10:1 to 20:

1.

6. The modification method according to claim 1, characterized in that, Step (2) The ball mill speed is 200~400 rpm; the ball milling time is 1-4 h.

7. The modification method according to claim 6, characterized in that, Perform a reverse rotation every 30 minutes of ball milling to ensure that the sum of the clockwise ball milling time equals the sum of the counterclockwise ball milling time.

8. A modified siderite composite material, obtained by modification using the method described in any one of claims 1-7.

9. The application of the modified siderite composite material according to claim 8 in activating persulfate degradation of organic pollutants.

10. The application according to claim 9, characterized in that, The organic pollutants mentioned include dichlorophenol.

11. The application according to claim 9 or 10, characterized in that, Treatment targets containing organic pollutants include water bodies and soil.

Images