Preparation method and application of a new Mg / Fe-containing supported material

Abstract

The application discloses a preparation method and application of a new Mg / Fe-containing loaded material, relates to the field of wastewater treatment, and comprises the following steps: dispersing magnetic iron oxide particles in an alkaline solution to prepare an alkaline iron oxide system solution; dissolving polyethylene glycol in a magnesium salt aqueous solution to prepare a magnesium salt system solution; and mixing and reacting the alkaline iron oxide system solution and the magnesium salt system solution, and then performing standing aging, suction filtration separation and grinding on the mixed solution after the reaction to obtain an intermediate product; the preparation method and application of the new Mg / Fe-containing loaded material have the synergistic effect of struvite crystallization and adsorption, can not only exhibit excellent removal effect on high-concentration nitrogen and phosphorus, but also have significant removal capacity for low-concentration phosphorus.

Description

Technical Field

[0001] This invention relates to wastewater treatment technology, specifically to a method for preparing a novel Mg / Fe supported material and its application. Background Technology

[0002] With the rapid development of industrialization and urbanization, the discharge of nitrogen and phosphorus-containing wastewater is increasing, posing a serious threat to the aquatic environment, such as causing eutrophication, leading to the proliferation of algae, and disrupting the aquatic ecological balance. At the same time, phosphorus is a non-renewable resource, and the recycling of phosphorus resources is urgent. Therefore, efficient and recyclable methods are needed to recover nitrogen and phosphorus from nitrogen and phosphorus wastewater to alleviate environmental pollution pressure, improve resource utilization, and reduce socio-economic costs.

[0003] Existing technology employs struvite crystallization to address the aforementioned problems. This method utilizes the reaction of magnesium ions with ammonia nitrogen and phosphates to generate insoluble compounds, thereby removing nitrogen and phosphorus from water. In nitrogen- and phosphorus-containing wastewater systems, when Mg... 2 + PO4 3- and NH4 + When the concentration of the ions meets the stoichiometric ratio and the reaction system reaches thermodynamic equilibrium, the above ions will spontaneously combine to form struvite crystals.

[0004] However, this struvite crystallization method faces problems such as high cost, difficulty in product recovery, high requirements for pH control, and large magnesium source dosage, which limit its promotion in the industrial field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a new Mg / Fe supported material and its application, in order to solve the problems of high cost, difficult product recovery, high pH control requirements and large magnesium source dosage in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a novel Mg / Fe supported material, comprising the following steps: An alkaline iron oxide system solution was prepared by dispersing magnetic iron oxide particles in an alkaline solution. A magnesium salt system solution was prepared by dissolving polyethylene glycol in an aqueous solution of magnesium salt; The alkaline iron oxide system solution was added dropwise to the magnesium salt system solution, and the mixture was stirred to react and obtain a mixed solution. After standing and aging, filtration and separation and grinding, an intermediate product was obtained. The intermediate product is loaded onto a carrier through hydrolysis-condensation or co-precipitation processes, and then calcined at high temperature to obtain a composite material.

[0007] Furthermore, the carrier is silica aerogel or lignin; wherein, when the carrier is silica aerogel, it is formed by loading through a hydrolysis-condensation process; and when the carrier is lignin, it is formed by loading through a co-precipitation process.

[0008] Furthermore, it includes the following steps: Step 1: A certain mass of magnetic iron oxide particles is uniformly dispersed in an alkaline solution to make the concentration of magnetic iron oxide 0.2-0.4 g / L, thus obtaining system A. The alkaline solution is an ammonia solution with a concentration of 0.6-0.9 mol / L. A magnesium salt aqueous solution and a polyethylene glycol aqueous solution were mixed evenly to make the magnesium salt concentration 1.0-1.5 mol / L and the polyethylene glycol concentration 10-15 g / L. The mixture was heated at 60-70℃ for 10-15 min to obtain system B. Step 2: Inject system A dropwise into system B while stirring. After system A is completely injected into system B, continue to stand and age at room temperature for 30-40 minutes. After aging, perform vacuum filtration and separation. Place the obtained precipitate in a forced-air drying oven and dry at 60-70 ℃ for 4 hours. Grind the dried precipitate into powder to obtain reaction product one. Step 3: Mix ethanol and tetraethyl orthosilicate evenly, adjust the pH to 2-5 with sulfuric acid solution, stir for 2 h to obtain system C; Ethanol and deionized water were mixed to obtain system D. System C was mixed with system D and then reaction product 1 was added. The pH was then adjusted to 8-11 with ammonia solution. The solution was then allowed to stand and allowed to gel. The resulting gel was then freeze-dried under vacuum. This process was repeated twice to obtain reaction product 2. Step 4: The reaction product 2 is loaded into a covered ceramic crucible. The covered ceramic crucible is placed in an air-atmosphere tube furnace with a heating rate of 5 ℃ / min~10 ℃ / min and a calcination temperature of 500 ℃~700 ℃ for high-temperature calcination for 2~3 h. After natural cooling to room temperature, the product is washed by centrifugation with water and methanol, and then placed in a forced-air drying oven for 4 hours to obtain a silica aerogel supported material containing Mg / Fe.

[0009] Furthermore, it includes the following steps: S1: After mixing lignin and magnetic iron oxide particles, the mixture is uniformly dispersed in an alkaline solution to obtain system A1, with the lignin concentration being 10-15 g / L and the magnetic iron oxide concentration being 0.9-1.1 g / L. The alkaline solution is an ammonia solution with a concentration of 0.6-0.9 mol / L. A magnesium salt aqueous solution and a polyethylene glycol aqueous solution were mixed evenly to make the magnesium salt concentration 1.0-1.5 mol / L and the polyethylene glycol concentration 10-15 g / L. The mixture was heated at 60-70℃ for 10-15 min to obtain system B. S2: System A1 is added dropwise to system B while stirring. After system A1 is completely added to system B, the mixture is allowed to stand and age at room temperature for 30-40 minutes. After aging, the mixture is separated by filtration. The precipitate is placed in a forced-air drying oven and dried at 60-70 °C for 4 hours. The dried precipitate is then ground into powder to obtain reaction product three. S3: The reaction product 3 is loaded into a covered ceramic crucible. The covered ceramic crucible is placed in an air-atmosphere tube furnace with a heating rate of 5℃ / min~10℃ / min and a calcination temperature of 500℃~700℃ for high-temperature calcination for 2~3 hours. After natural cooling to room temperature, the crucible is washed by centrifugation with water and methanol and then placed in a forced-air drying oven for 4 hours to obtain lignin-supported material containing Mg / Fe.

[0010] Furthermore, the volume ratio of ethanol to deionized water in step 3 is 1:1~2.

[0011] Further, in step 3, the volume ratio of ethanol to tetraethyl orthosilicate is 3:4~5, the concentration of sulfuric acid solution is 0.1 mol / L~1.0 mol / L, and the concentration of ammonia solution for adjusting pH is 0.1 mol / L~1.0 mol / L.

[0012] Application of a novel Mg / Fe supported material prepared by the method described above in the treatment of nitrogen and phosphorus wastewater.

[0013] In the preparation method of novel Mg / Fe supported materials, silica aerogel is preferably used as a carrier. Silica aerogel has the characteristics of low density, high porosity, large specific surface area, low cost, non-toxicity, and excellent thermal and chemical stability, which significantly improves the adsorption performance of the prepared material. Preferably, lignin is used as the carrier, as lignin has the characteristics of abundant active sites, low cost, non-toxicity, and high porosity; Magnetic iron oxides are not only low-cost and pollution-free, but also enable targeted enrichment and rapid separation of products.

[0014] Compared with the prior art, the method for preparing a novel Mg / Fe supported material and its application provided by the present invention have the following beneficial effects: 1. Through the synergistic effect of struvite crystallization and adsorption, it not only exhibits excellent removal effect on high concentrations of nitrogen and phosphorus, but also has a significant removal capacity for low concentrations of phosphorus. 2. By loading silica aerogel and lignin, abundant adsorption sites are provided for the composite material, which significantly enhances its adsorption capacity for nitrogen and phosphorus in water and increases the utilization rate of magnesium source. 3. The composite material has good magnetic separation ability and efficient nitrogen and phosphorus recovery ability. The recovered products can be used as slow-release fertilizers for resource utilization. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 The image shows the XRD pattern of the novel Mg / Fe supported material obtained in Example 1a of this invention. Figure 2 The image shows the XRD pattern of the novel Mg / Fe supported material obtained in Example 2a of this invention. Figure 3 These are SEM images of the novel Mg / Fe supported materials obtained in Examples 1a and 2a of this invention. Figure 4 The TP removal capacity of the novel Mg / Fe-containing supported materials obtained in Examples 1a and 2a of this invention after treating nitrogen and phosphorus wastewater of different concentrations; Figure 5 The TN removal capacity of the novel Mg / Fe-containing supported materials obtained in Examples 1a and 2a of this invention after treating nitrogen and phosphorus wastewater of different concentrations; Figure 6 The XRD patterns of the products obtained after treating high-concentration nitrogen and phosphorus wastewater and low-concentration nitrogen and phosphorus wastewater with the novel Mg / Fe-containing supported material obtained in Example 1a of the present invention. Figure 7 The XRD patterns are of the products obtained after treating high-concentration nitrogen and phosphorus wastewater and low-concentration nitrogen and phosphorus wastewater with the novel Mg / Fe-containing supported material obtained in Example 2a of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] As attached Figure 1 To be continued Figure 7 As shown.

[0019] Example 1:

[0020] Example 1a: This invention provides a method for preparing silica aerogel-supported Mg / Fe material, comprising the following steps: Step 1: Weigh 20 mg of magnetic nano-iron oxide particles and disperse them evenly in 100 mL of 0.6–0.9 mol / L ammonia solution to obtain system A. Add 0.296 g of polyethylene glycol to 20 mL of 1.0 mol / L magnesium sulfate solution, stir to dissolve, place in a constant temperature water bath and heat to 60°C for 10 minutes to obtain system B. Step 2: Inject system A dropwise into system B, stir to promote thorough mixing of the reactants. After system A is completely injected into system B, let it stand at room temperature for 30 minutes, then filter and separate. Place the obtained precipitate in a forced-air drying oven and dry it at 60°C for 4 hours. Grind it into powder to obtain reaction product one. Step 3: Mix ethanol and tetraethyl orthosilicate at a volume ratio of 3:4.5 until homogeneous. Adjust the pH to 2-5 with 0.1 mol / L to 1.0 mol / L sulfuric acid solution and stir for 2 hours to obtain system C. Mix ethanol and deionized water at a volume ratio of 1:1.2 to obtain system D. Take 5-10 mL of system C and system D and mix them thoroughly. Add 0.5-2.0 g of reaction product one. Then adjust the pH to 8-11 with 0.1 mol / L to 1.0 mol / L ammonia solution. Let the solution stand and wait for the gelation process. After gelation, freeze-dry twice under vacuum to obtain a fluffy reaction product two. Step 4: The reaction product 2 was loaded into a porcelain boat and placed in a tube furnace at 500℃~700℃ in air atmosphere with a heating rate of 5℃ / min~10℃ / min for 2 hours. After natural cooling to room temperature, the product was washed twice with water and methanol at 9000~10000rpm / min for 5~10 minutes each. The resulting product was then placed in a forced-air drying oven and dried at 60℃ for 4 hours to obtain a Mg / Fe silica aerogel-supported material with a yield of approximately 86%. The product of this embodiment was analyzed using a Rigaku MiniFlex 600 X-ray diffraction analyzer (Japan). For the results obtained, please refer to [link to relevant documentation]. Figure 1 .

[0021] Example 1b is basically the same as Example 1a, except that: Step 11: Weigh 0.64 g of magnetic nano-iron oxide particles and uniformly disperse them in 3.2 L of 0.6-0.9 mol / L ammonia solution to obtain system A. Add 9.52 g of polyethylene glycol to 0.64 L of 1.0 mol / L magnesium sulfate solution, stir to dissolve, heat to 60℃ and maintain for 30 minutes to obtain system B. Step 21: System A is added dropwise to system B. After stirring to promote thorough mixing of the reactants, the mixture is allowed to stand at room temperature for 2 hours. Then, it is separated by filtration. The precipitate is placed in a forced-air drying oven and dried at 60°C for 24 hours. The precipitate is then ground into powder to obtain reaction product one. Step 31: Mix 96 mL of ethanol and 140 mL of tetraethyl orthosilicate evenly, adjust the pH to 2-5 with 0.1 mol / L to 1.0 mol / L sulfuric acid solution, stir for 2 h to obtain system C. Mix ethanol and deionized water at a volume ratio of 1:1.2 to obtain system D. Take 0.15-0.30 L of system C and system D and mix them evenly. Add 20-30 g of reaction product one. Then adjust the pH to 8-11 with 0.1 mol / L to 1.0 mol / L ammonia solution. Let the solution stand and wait for the gelation process. After vacuum freeze-drying twice, obtain fluffy reaction product two. Step 41: The reaction product 2 was loaded into a ceramic boat and placed in a tube furnace. It was calcined for 2 hours at 500 ℃~700 ℃ in air at a heating rate of 5 ℃ / min~10 ℃ / min. After natural cooling to room temperature, it was washed twice by centrifugation with water and methanol at 9000~10000 rpm / min for 5~10 min each. The resulting product was placed in a forced-air drying oven and dried at 60 ℃ for 24 hours to obtain approximately 50 g of Mg / Fe silica aerogel supported material. The yield was basically the same as that of Example 1a.

[0022] Example 2:

[0023] Example 2a: This example is basically the same as the previous example, except that a method for preparing a lignin-supported Mg / Fe material includes the following steps: S1: 0.9226 g of sodium lignosulfonate and 100 mg of magnetic iron oxide particles were mixed and uniformly dispersed in 100 mL of 0.6–0.9 mol / L ammonia solution to obtain system A1; 0.296 g of polyethylene glycol was added to 20 mL of 1.0 mol / L magnesium sulfate solution, stirred to dissolve, and heated to 60 °C in a constant temperature water bath for 10 minutes to obtain system B; S2: System A1 is added dropwise to system B while stirring. After system A1 is completely added to system B, the mixture is allowed to stand and age at room temperature for 30 minutes. Then, it is filtered and separated. The precipitate is placed in a forced-air drying oven and dried at 60°C for 4 hours. The dried precipitate is then ground into powder to obtain reaction product three. S3: The reaction product 3 was placed in a covered ceramic crucible and calcined in a tube furnace at 500℃~700℃ in air atmosphere at a heating rate of 5℃ / min~10℃ / min for 2 hours. After natural cooling to room temperature, the product was washed twice with water and methanol at 9000~10000 rpm / min for 5~10 minutes each. The resulting product was then dried in a forced-air drying oven at 60℃ for 4 hours to obtain a lignin-supported material containing Mg / Fe, with a yield of approximately 30%. The product of this embodiment was analyzed using a Rigaku MiniFlex 600 X-ray diffraction analyzer. For the results, please refer to [link to relevant documentation]. Figure 2 .

[0024] Example 2b: This example is basically the same as Example 2a, except that: S11: Weigh 200 g of sodium lignosulfonate and 21.7 g of magnetic nano-iron oxide particles, and uniformly disperse them in 21.7 L of 0.6-0.9 mol / L ammonia solution to obtain system A1. Add 64.3 g of polyethylene glycol to 4.3 L of 1.0 mol / L magnesium sulfate aqueous solution, stir to dissolve, place in a constant temperature water bath and heat to 60℃ and maintain for 10 minutes to obtain system B. S21: System A1 is added dropwise to system B while stirring. After system A1 is completely added to system B, the mixture is allowed to stand and age at room temperature for 2 hours. Then, the mixture is filtered and separated. The precipitate is placed in a forced-air drying oven and dried at 60°C for 24 hours. The dried precipitate is then ground into powder to obtain reaction product three. S31: The reaction product 3 was placed in a covered ceramic crucible and placed in a tube furnace at 500 ℃~700 ℃ in air atmosphere at a heating rate of 5 ℃ / min~10 ℃ / min for 2 hours. After natural cooling to room temperature, the product was washed twice by centrifugation with water and methanol at a speed of 9000~10000 rpm / min for 5~10 min. The obtained product was placed in a forced-air drying oven and dried at 60 ℃ for 24 hours to obtain approximately 50 g of Mg / Fe lignin-supported material. The yield was basically unchanged compared to Example 2a.

[0025] Please see Figure 1 , Figure 2 ,Depend on Figure 1 , Figure 2 It can be seen that both materials contain MgO and Fe3O4; The Mg / Fe-containing silica aerogel-supported material obtained in Example 1a and the Mg / Fe-containing lignin-supported material obtained in Example 2a were analyzed using a JSM-7800F scanning electron microscope (JEOL Ltd.). The results from Example 1a are as follows: Figure 3As shown in (1) and (2) in the figure; the results obtained in Example 2a are as follows Figure 3 As shown in (3) and (4) in the figure.

[0026] Depend on Figure 3 As can be seen from (1) and (2) in Example 1a, the silica aerogel-supported material containing Mg / Fe prepared in Example 1a consists of obvious, petal-shaped pleated lamellar structure; while the lignin-supported material containing Mg / Fe prepared in Example 2a exhibits a thin-layered lamellar porous structure.

[0027] Experimental Example 1: Please see Figure 4 and Figure 5 To verify the Mg / Fe-containing supported materials prepared by the methods of Examples 1a and 2a, experiments were conducted to test the removal capacity of nitrogen and phosphorus wastewater with different concentrations. Nitrogen and phosphorus removal experiments were conducted by adding 75 mg of the Mg / Fe silica aerogel-supported material prepared in Example 1a and the Mg / Fe lignin-supported material prepared in Example 2a to 50 mL of a mixed solution of sodium dihydrogen phosphate dihydrate and ammonium chloride with initial concentrations of 0.5 mM to 10 mM (i.e., 0.5 mM, 1 mM, 1.5 mM, 2 mM, 4 mM, 6 mM, 8 mM, and 10 mM, respectively). The mixture was placed in a constant temperature shaker at 25°C and 180 r·min. -1 After the reaction lasted 6 hours, a 1 mL water sample was taken from each reaction system, filtered through a 0.45 µm filter membrane, and the total phosphorus content was measured. TP ) and total nitrogen ( TN The removal capacity of ) is calculated, and the results are as follows: Figure 4 and Figure 5 As shown; Depend on Figure 4 As can be seen from (1) in Example 1a, the Mg / Fe-containing silica aerogel-supported material obtained in Example 1a achieved a maximum TP removal capacity of 122.79 mg / g when the nitrogen and phosphorus wastewater concentration was 8 mM; Figure 4 As can be seen from (2) in Example 2a, the lignin-supported material containing Mg / Fe has a maximum TP removal capacity of 174.02 mg / g when the nitrogen and phosphorus wastewater concentration is 6 mM.

[0028] Depend on Figure 5 As can be seen from (1) in Example 1a, the Mg / Fe-containing silica aerogel-supported material achieved a maximum TN removal capacity of 47.67 mg / g when the nitrogen and phosphorus wastewater concentration was 8 mM; Figure 5As can be seen from (2) in Example 2a, the lignin-supported material containing Mg / Fe has a maximum TN removal capacity of 62.94 mg / g when the nitrogen and phosphorus wastewater concentration is 6 mM.

[0029] Experimental Example 2: Please see Figure 6 , Figure 7 To verify the Mg / Fe-containing supported materials prepared by the methods of Examples 1a and 2a, experiments were conducted on the products after treatment with high nitrogen and phosphorus concentrations and low nitrogen and phosphorus concentrations. Nitrogen and phosphorus removal experiments were conducted by adding 75 mg of the Mg / Fe silica aerogel-supported material prepared in Example 1a and the Mg / Fe lignin-supported material prepared in Example 2a to 50 mL of a mixed solution of sodium dihydrogen phosphate dihydrate and ammonium chloride with initial concentrations of 2 mM and 10 mM, respectively. The experiments were performed in a constant temperature shaker at 25°C and 180 r·min. -1 The reaction was carried out for 6 hours. After the reaction was completed, the solid reaction products were collected and dried.

[0030] The solid products of Mg / Fe silica aerogel-supported materials and Mg / Fe lignin-supported materials in nitrogen and phosphorus removal experiments were analyzed using a Rigaku MiniFlex 600 X-ray diffractometer (Japan). The results of the nitrogen and phosphorus removal experiments for the Mg / Fe silica aerogel-supported material are shown below. Figure 6 As shown; the results of nitrogen and phosphorus removal experiments of lignin-supported materials containing Mg / Fe are as follows. Figure 7 As shown.

[0031] Depend on Figure 6 , Figure 7 It can be seen that the Mg / Fe silica aerogel-supported material prepared in Example 1a and the Mg / Fe lignin-supported material prepared in Example 2a both showed a new mineral phase—struvite—after high-concentration treatment, proving that the two materials successfully converted nitrogen and phosphorus into high-value slow-release fertilizer through the "adsorption-crystallization" synergistic pathway.

[0032] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a novel Mg / Fe supported material, characterized in that, Includes the following steps: An alkaline iron oxide system solution was prepared by dispersing magnetic iron oxide particles in an alkaline solution. A magnesium salt system solution was prepared by dissolving polyethylene glycol in an aqueous solution of magnesium salt; The alkaline iron oxide system solution was added dropwise to the magnesium salt system solution, and the mixture was stirred to react and obtain a mixed solution. After standing and aging, filtration and separation and grinding, an intermediate product was obtained. The intermediate product is loaded onto a support through hydrolysis-condensation or co-precipitation processes, and then calcined at high temperature to obtain the new supported material.

2. The method for preparing a novel Mg / Fe supported material according to claim 1, characterized in that, The carrier is silica aerogel or lignin; wherein, when the carrier is silica aerogel, it is formed by loading through a hydrolysis-condensation process; when the carrier is lignin, it is formed by loading through a co-precipitation process.

3. The method for preparing a novel Mg / Fe supported material according to claim 2, characterized in that, Includes the following steps: Step 1: A certain mass of magnetic iron oxide particles is uniformly dispersed in an alkaline solution to make the concentration of magnetic iron oxide 0.2-0.4 g / L, thus obtaining system A. The alkaline solution is an ammonia solution with a concentration of 0.6-0.9 mol / mL. A magnesium salt aqueous solution and a polyethylene glycol aqueous solution were mixed evenly to make the magnesium salt concentration 1.0-1.5 mol / L and the polyethylene glycol concentration 10-15 g / L. The mixture was heated at 60-70℃ for 10-15 min to obtain system B. Step 2: Inject system A dropwise into system B while stirring. After system A is completely injected into system B, let it stand at room temperature for 30-40 minutes, then filter and separate. Place the precipitate in a forced-air drying oven and dry it at 60-70 ℃ for 4 hours. Grind the dried precipitate into powder to obtain reaction product one. Step 3: Mix ethanol and tetraethyl orthosilicate evenly, adjust the pH to 2-5 with sulfuric acid solution, stir for 2 h to obtain system C; Ethanol and deionized water were mixed to obtain system D. System C was mixed with system D and then reaction product 1 was added. The pH was then adjusted to 8-11 with ammonia solution. The solution was then allowed to stand and allowed to gel. The resulting gel was then freeze-dried under vacuum. This process was repeated twice to obtain reaction product 2. Step 4: The reaction product 2 is loaded into a covered ceramic crucible. The covered ceramic crucible is placed in an air-atmosphere tube furnace with a heating rate of 5℃ / min~10℃ / min and a calcination temperature of 500℃~700℃ for high-temperature calcination for 2~3 hours. After natural cooling to room temperature, the product is washed by centrifugation with water and methanol, and then placed in a forced-air drying oven for drying for 4 hours to obtain a silica aerogel supported material containing Mg / Fe.

4. The method for preparing a novel Mg / Fe supported material according to claim 2, characterized in that, Includes the following steps: S1: After mixing lignin and magnetic iron oxide particles, the mixture is uniformly dispersed in an alkaline solution to obtain system A1, with the lignin concentration being 10-15 g / L and the magnetic iron oxide concentration being 0.9-1.1 g / L. The alkaline solution is an ammonia solution with a concentration of 0.6-0.9 mol / L. A magnesium salt aqueous solution and a polyethylene glycol aqueous solution were mixed evenly to make the magnesium salt concentration 1.0-1.5 mol / L and the polyethylene glycol concentration 10-15 g / L. The mixture was heated at 60-70℃ for 10-15 min to obtain system B. S2: System A1 is added dropwise to system B while stirring. After system A1 is completely added to system B, the mixture is allowed to stand and age at room temperature for 30-40 minutes. Then, it is filtered and separated. The precipitate is placed in a forced-air drying oven and dried at 60-70 ℃ for 4 hours. The dried precipitate is ground into powder to obtain reaction product three. S3: The reaction product 3 was loaded into a covered ceramic crucible and placed in an air-atmosphere tube furnace with a heating rate of 5 ℃ / min~10 ℃ / min and a calcination temperature of 500 ℃~700 ℃ for high-temperature calcination for 2~3 h. After natural cooling to room temperature, the crucible was washed by centrifugation with water and methanol and then placed in a forced-air drying oven for 4 hours to obtain Mg / Fe lignin-supported material.

5. The method for preparing a novel Mg / Fe supported material according to claim 3, characterized in that, The volume ratio of ethanol to deionized water in step 3 is 1:1~2.

6. The method for preparing a novel Mg / Fe supported material according to claim 3, characterized in that, In step 3, the volume ratio of ethanol to tetraethyl orthosilicate is 3:4~5, the concentration of sulfuric acid solution is 0.1 mol / L~1.0 mol / L, and the concentration of ammonia solution for adjusting pH is 0.1 mol / L~1.0 mol / L.

7. The application of a novel Mg / Fe supported material prepared by the method according to any one of claims 1 to 6 in the treatment of nitrogen and phosphorus wastewater.

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