Phosphorus removal material as well as preparation method and application thereof

Abstract

The invention discloses a dephosphorization material and a preparation method and application thereof, the dephosphorization material comprises: a base material, the base material comprises SiO2, Al2O3, Fe2O3, CaO and MgO; elemental iron; and a plant foaming agent. The large-aperture structures uniformly distributed inside and outside the phosphorus removal material are beneficial to growth and attachment of microorganisms, and generation sites are provided for the removal process of phosphoric acid. The elemental iron contained in the material and phosphate undergo valence change through chemical combination to form hydroxyl and phosphorus flocculation so as to efficiently remove phosphorus pollution. In addition, due to the characteristics of oxidation-reduction capability, low cost, high porosity, difficulty in bonding, large specific surface area, high active iron content and the like of iron, the material has stronger electrochemical enrichment, physical adsorption and oxidation-reduction properties. Therefore, the traditional bottleneck is solved, and excellent efficiency is achieved in a biological filter and an artificial wetland.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental functional materials, and in particular relates to a phosphorus removal material and a preparation method and application thereof. Background Art

[0002] Agriculture currently faces a significant problem of water eutrophication due to phosphorus pollution. Increased fertilizer utilization leads to phosphorus accumulation in groundwater and surface water. Impervious surfaces created during urbanization increase surface runoff, ultimately triggering non-point source dispersed pollution in cities, causing eutrophication and habitat degradation in aquatic environments. Phosphorus and other pollutants are carried by runoff into rivers and lakes, further impacting the sustainable use of freshwater resources. Therefore, it is necessary to promptly control the circulation of exogenous phosphorus in the aquatic environment.

[0003] Commonly used phosphorus removal technologies include coagulation, chemical precipitation, microbial treatment, ion exchange membrane separation and adsorption. When there are trace amounts of phosphorus in water, simple biological treatment methods cannot achieve maximum efficiency, resulting in waste of resources. Chemical precipitation methods usually require the addition of large amounts of metals, aluminum salts, etc., which are costly and have prominent problems such as secondary pollution. The adsorption method is highly efficient in capturing excess phosphorus in water, has a wide range of applications, is simple to operate, and has good phosphorus removal capabilities. At the same time, the addition of iron to the material helps phosphates capture metal sites through ligand exchange during the phosphorus adsorption process, which is beneficial for phosphorus removal. However, this method has the problems of uncontrollable iron ion release rate, single chemical action mechanism, and material pore structure that is not conducive to microbial synergy, which limits the further improvement of phosphorus removal capacity. Therefore, it is particularly important to explore a new low-cost composite phosphorus removal material to further improve the phosphorus removal rate. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art to a certain extent. To this end, the present invention provides a phosphorus removal material and its preparation method and application. The phosphorus removal material of the present invention has a high phosphorus removal capacity.

[0005] Therefore, in a first aspect, the present invention provides a phosphorus removal material comprising: a base material comprising SiO2, Al2O3, Fe2O3, CaO, and MgO; elemental iron; and a plant foaming agent. Thus, the phosphorus removal material of the present invention exhibits excellent phosphorus removal performance.

[0006] In some embodiments, the mass percentage of the matrix material is 66.5-72.5%, the mass percentage of elemental iron is 27-33%, and the mass percentage of the plant foaming agent is 0.1-0.5%.

[0007] In some embodiments, the particle size of the iron element is 150-250 mesh.

[0008] In some embodiments, the plant foaming agent includes at least one of apple amino acid and coconut oil.

[0009] In a second aspect of the present invention, a method for preparing the phosphorus-removing material of the first aspect is provided, including the following steps: mixing limestone and clay and then performing heat treatment to form a powder; mixing the powder with elemental iron, a plant foaming agent, and water, and performing curing treatment to obtain the phosphorus-removing material. Thus, the method for preparing the phosphorus-removing material of the present invention is simple to operate, environmentally friendly, and the prepared phosphorus-removing material will have excellent phosphorus-removing effects.

[0010] In some embodiments, in the step of mixing limestone and clay and then performing heat treatment, the heat treatment temperature is 1200 - 1600 °C.

[0011] In some embodiments, the specific surface area of the powder is 360 - 400 m 2 / kg.

[0012] In some embodiments, the mass ratio of limestone to clay is (15 - 16)∶(4 - 5).

[0013] In some embodiments, in the step of mixing the powder with elemental iron, a plant foaming agent, and water, the addition amount of elemental iron is 40 - 43% of the mass of the powder, and the mass ratio of the plant foaming agent to water is 1∶(40 - 60).

[0014] In a third aspect of the present invention, the application of the phosphorus-removing material of the first aspect, or the phosphorus-removing material obtained by the preparation method of the second aspect, in the treatment of phosphorus pollution is provided, including sewage treatment and rainwater runoff purification. Thus, the phosphorus-removing material of the present invention can effectively treat phosphorus pollution in water bodies.

[0015] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0017] Figure 1 is the phosphorus-removing effect after long-term operation of the phosphorus-removing material in Example 1 of the present invention;

[0018] Figure 2 is the treatment effect of the phosphorus-removing material in Example 1 of the present invention on different concentrations of phosphorus. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The embodiments of the present invention will be described in detail below. The following described embodiments are exemplary and are only used to explain the present invention, and should not be construed as a limitation to the present invention.

[0020] It should be noted that the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] In this document, the term "comprising" or "including" is an open expression, that is, it includes the content specified by the present invention, but does not exclude other aspects of the content.

[0023] In the first aspect of the embodiments of the present invention, the present invention provides a phosphorus removal material, which includes: a matrix material, the matrix material includes SiO2, Al2O3, Fe2O3, CaO, MgO; elemental iron; a plant foaming agent.

[0024] In the present invention, the phosphorus removal system is a liquid system, and phosphorus exists in the form of dissolved phosphate ions. In the phosphorus removal material of the present invention, the matrix material serves as the main structure, providing a variety of reactive sites and also providing a loading site for elemental iron, enabling the elemental iron to be uniformly dispersed in the material, which helps to increase the contact area between the elemental iron and the phosphorus-containing wastewater and improve the phosphorus removal efficiency. The addition of the foaming agent will change the overall structure of the material, increase the pore size of the material, which helps to increase the adsorption capacity of the material and also provides growth sites for microorganisms. SiO2 in the matrix material can provide a stable framework structure and enhance the mechanical strength of the material; Al2O3 combines with phosphate ions through aluminum-oxygen bonds (such as forming AlPO4), which is suitable for acidic environments; Fe2O3 forms FePO4 precipitates with phosphate ions or undergoes ligand exchange adsorption on the surface; CaO through Ca 2+It promotes the removal of phosphate. The matrix material is mainly alkaline, and the reaction can generate Ca(OH)2. Ca(OH)2 and phosphate form Ca(PO4)9(OH)2 and CaHPO4 through the connection of hydroxyl functional groups, thereby increasing the phosphorus removal effect. Si, Al, and Ca in the filler combine with hydroxide to form active groups, which react with phosphate by complexation; Phosphate can also directly capture metal sites on the material surface through ligand exchange, thereby releasing excess hydroxide. After the pH gradually increases, the active sites of iron and phosphate jointly deprotonate and carry negative charges, and there will be an electron donor-acceptor relationship between them, forming a coordination bond to enhance the phosphorus removal ability. During the process of removing pollutants, carbonates are generated to act as pH buffers, which also improve the situation of low pH. At the same time, the released OH - can also be flocculated and stored with phosphate to improve the phosphorus removal efficiency. MgO has a higher solubility and can combine with PO4 3- to form Mg3(PO4)2. In the present invention, the iron element mainly undergoes a valence change through chemical combination with phosphate (Fe-Fe2 + -Fe3 + valence cycle) to form flocs of hydroxide and phosphorus to efficiently remove phosphorus pollution. At the same time, the change in the valence of iron changes the redox potential in the system, thereby promoting the phosphorus removal process and promoting the adsorption and complexation of phosphorus. The plant foaming agent can generate pores during the material preparation process, forming a porous structure, increasing the specific surface area and adsorption sites. Therefore, the phosphorus removal material of the present invention has a high phosphorus removal rate.

[0025] In some embodiments of the present invention, by mass percentage, the mass percentage content of the matrix material is 66.5-72.5%, the mass percentage content of the iron element is 27-33%, and the mass percentage content of the plant foaming agent is 0.1-0.5%.

[0026] When the phosphorus removal material provided by the embodiment of the present invention meets the above conditions, the phosphorus removal material will have excellent phosphorus adsorption performance and can further improve the phosphorus removal rate.

[0027] As an example, the mass percentage content of the matrix material is 66.5%, 68%, 70%, 72%, 72.5%, etc.; the mass percentage content of the iron element is 27%, 29%, 30%, 31%, 33%, etc.; the mass percentage content of the plant foaming agent is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.

[0028] In some embodiments of the present invention, the particle size of the iron element is 150-250 mesh.

[0029] When the particle size of the elemental iron provided in the embodiments of the present invention is 150 - 250 mesh, it can provide sufficient active sites to ensure sufficient phosphate adsorption or precipitation (such as forming FePO4). Thus, it is beneficial to improve the phosphorus removal rate of the material.

[0030] As an example, the particle size of the elemental iron is 150 mesh, 180 mesh, 200 mesh, 220 mesh, 240 mesh, 250 mesh, etc.

[0031] In some embodiments of the present invention, the plant foaming agent includes at least one of apple amino acid and coconut oil. Thus, it is beneficial to improve the phosphorus removal rate of the material.

[0032] In the second aspect of the embodiments of the present invention, the present invention provides a method for preparing the phosphorus removal material of the first aspect, including the following steps: mixing limestone and clay and then performing heat treatment to make a powder; mixing the powder with elemental iron, a plant foaming agent and water, and performing curing treatment to obtain the phosphorus removal material.

[0033] The preparation method of the phosphorus removal material in the present invention is simple in operation and environmentally friendly. First, limestone and clay are heat-treated (such as high-temperature calcination) and then made into a powder. Among them, limestone decomposes into CaO, and clay is activated to generate active oxides (such as CaO, SiO2, Al2O3, etc.), providing a basic environment and a porous structure basis for subsequent reactions. Then, it is mixed with elemental iron and a plant foaming agent to generate a pore structure in the material, increasing the specific surface area and adsorption sites, and improving the removal rate of phosphorus in water. Thus, the phosphorus removal material obtained by the preparation method of the present invention has a high phosphorus removal rate.

[0034] In some embodiments of the present invention, in the step of mixing limestone and clay and then performing heat treatment, the heat treatment temperature is 1200 - 1600 °C. Thus, it is beneficial to the high-temperature decomposition of limestone and clay to generate active oxides, thereby being beneficial to improving the performance of the phosphorus removal material.

[0035] As an example, the heat treatment temperature is 1200 °C, 1300 °C, 1400 °C, 1500 °C, 1600 °C, etc.

[0036] In some embodiments of the present invention, the specific surface area of the powder is 360 - 400 m 2 / kg.

[0037] During the preparation process of the phosphorus removal material in the present invention, the specific surface area of the powder affects the phosphorus removal efficiency of the material. A specific surface area of 360 - 400 m 2 / kg can balance the reaction kinetics and the material stability, ensure sufficient active sites, and is beneficial to improving the phosphorus adsorption capacity.

[0038] As an example, the specific surface area of the powder is 360 m 2 / kg, 370 m2 / kg、380m 2 / kg、390m 2 / kg、400m 2 / kg, etc.

[0039] In some embodiments of the present invention, the mass ratio of limestone to clay is (15-16):(4-5).

[0040] In the preparation method provided by the embodiment of the present invention, when the mass ratio of limestone to clay meets the above conditions, it is conducive to the precise regulation of the chemical synergy of the components in the system, playing a synergistic role of chemical precipitation + adsorption, ensuring that the material maximizes the phosphorus removal efficiency while ensuring the stability of the material in terms of strength, porosity, anti-expansion performance, etc.

[0041] As an example, the mass ratio of limestone to clay is 15:5, 15.5:4.5, 16:4, and so on.

[0042] In some embodiments of the present invention, in the step of mixing the powder with elemental iron, a plant foaming agent and water, the amount of elemental iron added is 40-43% of the mass of the powder, and the mass ratio of the plant foaming agent to water is 1:(40-60).

[0043] The ratio of the plant foaming agent to water in the present invention directly affects the pore size and density of the material, thereby affecting the material's adsorption properties. When the embodiments of the present invention meet the above conditions, it is beneficial to obtain a phosphorus removal material with excellent performance. This can further improve the performance of the phosphorus removal material.

[0044] As an example, the amount of iron added is 40%, 41%, 42%, 43% of the powder mass, etc.; the mass ratio of plant foaming agent to water is 1:40, 1:45, 1:47, 1:49, 1:50, 1:52, 1:54, 1:55, 1:60, etc.

[0045] In the third aspect of the embodiments of the present invention, the present invention proposes the application of the phosphorus removal material of the first aspect, or the phosphorus removal material obtained by the preparation method of the second aspect, in phosphorus pollution control, including sewage treatment and rainwater runoff purification.

[0046] It will be understood by those skilled in the art that the features and advantages described above for the phosphorus removal material and the phosphorus removal material obtained by the preparation method of the present invention are also applicable to this application and will not be repeated here.

[0047] The solution of the present invention will be explained below in conjunction with embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those without specific techniques or conditions noted in the embodiments, the techniques or conditions described in the literature in this field or according to the product specifications are followed. Those reagents or instruments without the manufacturer noted are all conventional products that can be obtained through commercial purchases.

[0048] Example 1:

[0049] (1) The limestone and clay raw materials are crushed and ground, and then fired at a high temperature of 1400 °C into a molten small iron ball state. Then it is ground by a powder mill into a powder with a specific surface area of 380 m 2 / kg. The powder contains 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0050] (2) Prepare 5 g of plant foaming agent, mix it with 0.25 kg of water and stir evenly, then put it into a foaming machine, introduce air to generate dense foam. Add 0.48 kg of 150-mesh elemental iron to 1.2 kg of the above powder and mix well. Mix all the foam in and inject 0.5 kg of water, then stir evenly. Place it in a square mold and cure for 5 days. Repeat spraying water every day and then let it dry naturally. The material changes from crispy to hard, obtaining a phosphorus-removing material, where the mass ratio of the matrix material is 66.5%, the mass ratio of elemental iron is 33%, and the mass ratio of the plant foaming agent is 0.5%.

[0051] Example 2:

[0052] (1) The limestone and clay raw materials are crushed and ground, and then fired at a high temperature of 1600 °C into a molten small iron ball state. Then it is ground by a powder mill into a powder with a specific surface area of 400 m 2 / kg. The powder contains 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0053] (2) Prepare 5 g of plant foaming agent, mix it with 0.25 kg of water and stir evenly, then put it into a foaming machine, introduce air to generate dense foam. Add 0.52 kg of 200-mesh elemental iron to 1.2 kg of the above powder and mix well. Mix all the foam in and inject 0.5 kg of water, then stir evenly. Place it in a square mold and cure for 3 days. Repeat spraying water every day and then let it dry naturally. The material changes from crispy to hard, obtaining a phosphorus-removing material, where the mass ratio of the matrix material is 72.5%, the mass ratio of elemental iron is 27%, and the mass ratio of the plant foaming agent is 0.5%.

[0054] Example 3:

[0055] (1) The limestone and clay raw materials are crushed and ground, and then fired at a high temperature of 1200 °C to form a molten small iron ball state. Then it is ground into a powder with a specific surface area of 360 m 2 / kg. The powder contains 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0056] (2) Prepare 5 g of plant foaming agent, mix it with 0.25 kg of water and stir evenly, then put it into a foaming machine, introduce air to generate dense foam. Add 0.5 kg of 180-mesh elemental iron to 1.2 kg of the above powder and mix well. Mix all the foam into it, inject 0.5 kg of water and stir evenly. Place it in a square mold and cure for 4 days. Repeat spraying water every day and then dry it naturally. The material changes from crispy to hard, and the phosphorus removal material is obtained. Among them, the mass ratio of the matrix material is 68%, the mass ratio of elemental iron is 31.7%, and the mass ratio of the plant foaming agent is 0.3%.

[0057] Comparative Example 1:

[0058] The difference between Comparative Example 1 and Example 1 is that elemental iron is not added in Comparative Example 1.

[0059] I. Physical property tests:

[0060] 1. Material porosity test: The material porosity is measured through an indoor saturated water test. First, dry the specimen and weigh its dry mass md. Then place the specimen in pure water for saturation treatment. The entire saturation process lasts for 48 h to ensure that the specimen is completely saturated with water, and measure the mass ms of the saturated specimen. The porosity p1 of the specimen can be calculated by the following formula:

[0061] p1 = (ms - md) / ρw * V (ρw is the density of water, and V is the filler volume)

[0062] 2. Specific surface area test: Use the ASAP2020 type full-automatic specific surface area analyzer of Micromeritics Corporation in the United States to characterize the specific surface area of the filler.

[0063] 3. Compressive strength: Test it using a HYE-2000 type electro-hydraulic constant loading pressure testing machine.

[0064] 4. Pore size: Control the final pore size of the matrix material by adjusting the content of the foaming machine.

[0065] II. Test results:

[0066] After testing, the physical property parameters of the phosphorus removal materials in the above examples and comparative examples are shown in Table 1.

[0067] Table 1 Physical Property Parameters of the Phosphorus Removal Materials in the Examples and Comparative Examples

[0068] Number Porosity / % <![CDATA[Specific surface area / m 2 / g]]> Compressive strength / MPa Pore size / mm Example 1 76 40 15 2 Example 2 80 45 21 5 Example 3 82 50 28 8 Comparative Example 1 78 38 12 4

[0069] As can be seen from Table 1, compared with the phosphorus removal material of Comparative Example 1, the phosphorus removal material of the embodiment of the present invention has excellent performance, and thus has excellent phosphorus removal effect.

[0070] Furthermore, in order to test the phosphorus removal effect of the phosphorus removal material of the present invention, the phosphorus removal material of Example 1 of the present invention was operated in a continuous flow device with an influent concentration of PO4 3 - of 2 mg / L for 75 days, and its phosphorus removal effect was detected. At the same time, the traditional phosphorus removal material of Comparative Example 1 was used as a control. The test results are as Figure 1 shown. The functional filler in the figure is the phosphorus removal material of the present invention. According to Figure 1 it can be seen that the phosphorus removal ability of the phosphorus removal material of the present invention is significantly higher than that of Comparative Example 1, and the highest removal ability of the present invention is increased by 25.4%. And after 25 days, the material of Comparative Example 1 gradually tended to be saturated, the removal ability decreased, and showed a continuous downward trend, while the phosphorus removal ability of the phosphorus removal material of the present invention always maintained at about 90%. This shows that the phosphorus removal material of the present invention has a high phosphorus removal effect.

[0071] In order to test the removal and tolerance of the phosphorus removal material of Example 1 of the present invention to different concentrations of phosphorus, treatment experiments were carried out on sewage with 6 different phosphorus concentrations (0.5 mg / L, 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L). At the same time, the traditional phosphorus removal material of Comparative Example 1 was used as a control. The test results are as Figure 2 shown. The functional filler in the figure is the phosphorus removal material of the present invention. Through comparison, it is found that when operating for 10 days, the phosphorus removal ability of the material of Comparative Example 1 decreases instead as the phosphorus concentration increases, and when the operation time increases to 30 days, the removal ability decreases significantly. While the phosphorus removal rate of the phosphorus removal material of the present invention still maintains a high level after the concentration increases, and after continuously operating for 30 days, the phosphorus removal ability still remains at about 80%, which is significantly better than that of Comparative Example 1.

[0072] The phosphorus removal material of Example 2 of the present invention was operated in a continuous flow device with an influent concentration of PO4 3 - of 2 mg / L for 75 days, and its phosphorus removal effect was detected. At the same time, the traditional phosphorus removal material of Comparative Example 1 was used as a control. The test results show that the phosphorus removal material of the present invention always shows an upward state in the first 35 days, and the phosphorus removal rate reaches 93.82% on the 30th day, and then tends to rise steadily. The phosphorus removal effect always reaches more than 93% after 35 days. While the traditional filler (Comparative Example 1) has a gradually increasing removal effect before 15 days and reaches 64.73% on the 15th day, and the overall removal effect does not exceed 70%.

[0073] The phosphorus removal material of Embodiment 3 of the present invention was operated in a continuous flow device with an influent concentration of 2 mg / L of PO4 3 -, and its phosphorus removal effect was detected for 75 days. At the same time, the traditional phosphorus removal material of Comparative Example 1 was used as a control. The test results show that the phosphorus removal material of the present invention showed an upward trend in the first 29 days, and the phosphorus removal rate reached 87.82% on the 29th day, and then tended to increase steadily. The phosphorus removal effect has always reached more than 89% after 35 days. The removal effect of the traditional packing gradually improved before 15 days and reached 64.73% on the 15th day, and the overall removal effect did not exceed 70%.

[0074] Therefore, it shows that the phosphorus removal material of the present invention has a high phosphorus removal rate and stable performance.

[0075] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0076] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A phosphorus removal material, characterized in that, The phosphorus removal material includes: A matrix material, which includes SiO2, Al2O3, Fe2O3, CaO, and MgO; Elemental iron; A plant foaming agent.

2. The phosphorus removal material according to claim 1, wherein By mass percentage, the mass percentage content of the matrix material is 66.5 - 72.5%, the mass percentage content of the elemental iron is 27 - 33%, and the mass percentage content of the plant foaming agent is 0.1 - 0.5%.

3. The phosphorus-removing material according to claim 1 or 2, characterized in that, The particle size of the elemental iron is 150 - 250 mesh.

4. The phosphorus removal material according to claim 1 or 2, characterized in that, The plant foaming agent includes at least one of apple amino acid and coconut oil.

5. A method for preparing the phosphorus removal material according to any one of claims 1 to 4, characterized in that It includes the following steps: Mix limestone and clay and then perform heat treatment to make powder; Mix the powder with elemental iron, a plant foaming agent, and water, and perform curing treatment to obtain the phosphorus removal material.

6. The method according to claim 5, characterized in that, In the step of mixing the powder with elemental iron, a plant foaming agent, and water, the addition amount of the elemental iron is 40 - 43% of the mass of the powder, and the mass ratio of the plant foaming agent to the water is 1:(40 - 60).

7. The method according to claim 5 or 6, characterized in that, The specific surface area of the powder is 360 to 400 m 2 / kg.

8. The method according to any one of claims 5 to 7, characterized in that The mass ratio of the limestone to the clay is (15 - 16):(4 - 5).

9. The method according to any one of claims 5 to 8, characterized in that In the step of mixing limestone and clay and then performing heat treatment, the heat treatment temperature is 1200 - 1600 °C.

10. The application of the phosphorus removal material according to any one of claims 1 to 4, or the phosphorus removal material obtained by the preparation method according to any one of claims 5 to 9 in the treatment of phosphorus pollution, including sewage treatment and rainwater runoff purification.

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