Phosphorus removal material, method for preparing the same, and use thereof

Abstract

The application discloses a phosphorus removal material and a preparation method and application thereof. The phosphorus removal material comprises a base material, the base material comprises SiO2, Al2O3, Fe2O3, CaO and MgO, and the phosphorus removal material further comprises elemental iron and a plant foaming agent. The large-pore structure of the phosphorus removal material is uniformly distributed inside and outside the material, which is beneficial to the growth and adhesion of microorganisms and provides a site for the removal of phosphoric acid. The elemental iron in the material is combined with phosphate through chemical combination to change the valence state, form hydroxyl and phosphorus flocculation, and efficiently remove phosphorus pollution. In addition, the material has strong electrochemical enrichment, physical adsorption and redox performance due to the redox capacity of iron, low cost, high porosity, difficulty in bonding, large specific surface area, high active iron content and other characteristics. The material can solve the traditional bottleneck and has excellent performance in a biological filter and a constructed wetland.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a phosphorus removal material, its preparation method, and its application. Background Technology

[0002] Currently, agriculture faces a prominent problem of eutrophication caused by phosphorus pollution. Increased fertilizer utilization leads to phosphorus accumulation in groundwater and surface water. The construction of impermeable surfaces during urbanization increases surface runoff, ultimately causing non-point source pollution in cities, resulting in eutrophication of aquatic environments and habitat degradation. Pollutants such as phosphorus gradually flow into rivers and lakes with runoff, further impacting the sustainable use of freshwater resources. Therefore, it is necessary to promptly curb the cycling of exogenous phosphorus in the aquatic environment.

[0003] Commonly used phosphorus removal technologies include coagulation, chemical precipitation, microbial methods, ion exchange membrane separation, and adsorption. When phosphorus levels in water are trace, simple biological treatment methods cannot achieve maximum efficiency, resulting in resource waste. Chemical precipitation typically requires the addition of large amounts of metals and aluminum salts, leading to high costs and significant secondary pollution. Adsorption, on the other hand, is highly efficient, widely applicable, simple to operate, and has good phosphorus removal capabilities. Furthermore, the addition of iron to the material helps phosphates capture metal sites through ligand exchange during phosphorus adsorption, thus facilitating phosphorus removal. However, this method suffers from uncontrollable iron ion release rates, a single chemical mechanism, and a porous structure that hinders microbial synergy, limiting further improvements in phosphorus removal capacity. Therefore, exploring a novel, low-cost composite phosphorus removal material is crucial to further improve phosphorus removal rates. Summary of the Invention

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

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

[0006] In some embodiments, the matrix material comprises 66.5% to 72.5% by mass, the elemental iron comprises 27% to 33% by mass, and the plant-based foaming agent comprises 0.1% to 0.5% by mass.

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

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

[0009] In a second aspect, the present invention provides a method for preparing the phosphorus removal material of the first aspect, comprising the following steps: mixing limestone and clay and then heat-treating the mixture to form a powder; mixing the powder with elemental iron, a plant-based foaming agent, and water, and then curing the mixture to obtain the phosphorus removal material. Therefore, the method for preparing the phosphorus removal material of the present invention is simple to operate, environmentally friendly, and the prepared phosphorus removal material will have excellent phosphorus removal effect.

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

[0011] In some embodiments, the specific surface area of ​​the powder is 360–400 m². 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, plant-based foaming agent and water, the amount of elemental iron added is 40-43% of the powder mass, and the mass ratio of plant-based foaming agent to water is 1:(40-60).

[0014] In a third aspect, 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 wastewater treatment and rainwater runoff purification. Thus, the phosphorus removal material of the present invention can effectively treat phosphorus pollution in water bodies.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

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

[0017] Figure 1 The phosphorus removal effect of the phosphorus removal material in Example 1 of this invention after long-term operation;

[0018] Figure 2 This illustrates the effect of the phosphorus removal material in Example 1 of the present invention on phosphorus of different concentrations. Detailed Implementation

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

[0020] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] In this document, the terms “comprising” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

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

[0024] In this invention, the phosphorus removal system is a liquid system, with phosphorus existing in the form of dissolved phosphate ions. In the phosphorus removal material of this invention, the matrix material serves as the main structure, providing multiple reactive sites and also providing loading sites for elemental iron, allowing elemental iron to be uniformly dispersed in the material. This helps increase the contact area between elemental iron and phosphorus-containing wastewater, improving phosphorus removal efficiency. The addition of a foaming agent alters the overall structure of the material, increasing the pore size and thus enhancing its adsorption capacity, while also providing growth sites for microorganisms. SiO2 in the matrix material provides a stable framework structure, enhancing the material's mechanical strength; Al2O3 combines with phosphate ions through aluminum-oxygen bonds (e.g., forming AlPO4), suitable for acidic environments; Fe2O3 forms FePO4 precipitate with phosphate ions, or undergoes ligand exchange adsorption on the surface; CaO is adsorbed through Ca... 2+The process promotes phosphate removal. The matrix material is primarily alkaline, and the reaction generates Ca(OH)₂. Ca(OH)₂ and phosphate ions are linked through hydroxyl functional groups to form Ca(PO₄)₉(OH)₂ and CaHPO₄, thereby increasing phosphorus removal efficiency. Si, Al, and Ca in the packing material combine with hydroxide ions to form active groups, which undergo complexation reactions with phosphate. Phosphate can also directly capture metal sites on the material surface through ligand exchange, releasing excess hydroxide ions. As the pH gradually increases, the active sites of iron and phosphate ions jointly lose protons and become negatively charged, forming electron donor-acceptor relationships and coordination bonds, thus enhancing phosphorus removal capacity. During pollutant removal, carbonates are generated, acting as pH buffers and improving low pH conditions. Simultaneously, the released OH⁻... - It can also be stored with phosphate flocculation to improve phosphorus removal efficiency. MgO has higher solubility and can combine with PO4. 3- Mg3(PO4)2 is formed. In this invention, elemental iron mainly undergoes a valence state change through chemical bonding with phosphate (Fe-Fe2+). + -Fe3 + The phosphorus removal material utilizes a valence state cycle to form flocculation of hydroxide ions and phosphorus, thereby efficiently removing phosphorus pollution. Simultaneously, the change in the valence state of iron alters the redox potential within the system, promoting the phosphorus removal process and facilitating phosphorus adsorption and complexation. Plant-based foaming agents generate pores during material preparation, forming a porous structure that increases specific surface area and adsorption sites. Therefore, the phosphorus removal material of this invention exhibits a high phosphorus removal rate.

[0025] In some embodiments of the present invention, the matrix material comprises 66.5% to 72.5% by mass, the elemental iron comprises 27% to 33% by mass, and the plant-based foaming agent comprises 0.1% to 0.5% by mass.

[0026] When the phosphorus removal material provided in this embodiment of the 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 examples, the mass percentage of the matrix material is 66.5%, 68%, 70%, 72%, 72.5%, etc.; the mass percentage of elemental iron is 27%, 29%, 30%, 31%, 33%, etc.; and the mass percentage of plant-based 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 elemental iron is 150-250 mesh.

[0029] When the iron element particle size provided in this embodiment of the invention is 150-250 mesh, it can provide sufficient active sites to ensure sufficient phosphate adsorption or precipitation (such as the formation of FePO4). This is beneficial for improving the phosphorus removal rate of the material.

[0030] For example, the particle size of 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-based foaming agent includes at least one of apple amino acids and coconut oil. This is beneficial for improving the phosphorus removal rate of the material.

[0032] In a second aspect of the present invention, the present invention proposes a method for preparing the phosphorus removal material of the first aspect, comprising the following steps: mixing limestone and clay and then heat-treating to form a powder; mixing the powder with elemental iron, a plant foaming agent and water, and then curing to obtain the phosphorus removal material.

[0033] The preparation method of the phosphorus removal material of this invention is simple to operate and environmentally friendly. First, limestone and clay are heat-treated (e.g., calcined at high temperature) to produce powder. The limestone decomposes into CaO, and the clay is activated to generate active oxides (such as CaO, SiO2, Al2O3, etc.), providing an alkaline environment and a porous structure for subsequent reactions. Then, it is mixed with elemental iron and a plant-based foaming agent to create a porous structure in the material, increasing the specific surface area and adsorption sites, thereby improving the phosphorus removal rate in water. Therefore, the phosphorus removal material prepared by the method of this invention has a high phosphorus removal rate.

[0034] In some embodiments of the present invention, in the step of heat treatment after mixing limestone and clay, the heat treatment temperature is 1200–1600°C. This facilitates the high-temperature decomposition of limestone and clay, generating active oxides, thereby improving the performance of the phosphorus removal material.

[0035] For example, the heat treatment temperatures are 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, etc.

[0036] In some embodiments of the present invention, the specific surface area of ​​the powder is 360–400 m². 2 / kg.

[0037] In the preparation process of the phosphorus removal material of the present invention, the specific surface area of ​​the powder affects the phosphorus removal efficiency of the material, 360-400m² 2 A specific surface area of ​​ / kg can balance reaction kinetics and material stability, ensuring sufficient active sites and thus improving phosphorus adsorption capacity.

[0038] As an example, the specific surface area of ​​the powder is 360 m². 2 / kg, 370m2 / 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 embodiments of the present invention, when the mass ratio of limestone to clay meets the above conditions, it is beneficial to the precise control of the chemical synergistic effect of each component in the system, so as to achieve chemical precipitation + adsorption synergy, ensure that the material can maximize phosphorus removal efficiency, and at the same time ensure the stability of the material in terms of strength, porosity, and anti-expansion performance.

[0041] For example, the mass ratio of limestone to clay is 15:5, 15.5:4.5, 16:4, etc.

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

[0043] The ratio of plant-based foaming agent to water in this invention directly affects the pore size and density of the material, thereby influencing its adsorption performance. When the embodiments of this invention meet the above conditions, it is beneficial to obtain a phosphorus removal material with excellent performance. Therefore, the performance of the phosphorus removal material can be further improved.

[0044] As examples, the amount of elemental 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 a third aspect of the present invention, the present invention proposes the application of phosphorus removal materials of the first aspect, or phosphorus removal materials obtained by the preparation method of the second aspect, in phosphorus pollution control, including wastewater treatment and rainwater runoff purification.

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

[0047] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0048] Example 1:

[0049] (1) The limestone and clay raw materials are crushed and ground into fine powder, then fired at 1400℃ to form molten small iron balls. These balls are then ground in a grinding mill to achieve a specific surface area of ​​380 m². 2 / kg powder, containing 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0050] (2) Prepare 5g of plant-based foaming agent, mix it with 0.25kg of water, stir well, and put it into a foaming machine. Introduce air to produce dense foam. Add 0.48kg of 150-mesh elemental iron to 1.2kg of the above powder and mix thoroughly. Mix all the foam into the mixture and add 0.5kg of water. Stir well and place it in a square mold for curing for 5 days. Spray water repeatedly every day and then let it dry naturally. The material changes from brittle to hard, and a phosphorus removal material is obtained. The mass ratio of the matrix material is 66.5%, the mass ratio of elemental iron is 33%, and the mass ratio of plant-based foaming agent is 0.5%.

[0051] Example 2:

[0052] (1) The limestone and clay raw materials are crushed and ground into fine powder, then fired at 1600℃ to form molten small iron balls. These balls are then ground in a grinding mill to achieve a specific surface area of ​​400 m². 2 / kg powder, containing 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0053] (2) Prepare 5g of plant-based foaming agent, mix it with 0.25kg of water, stir well, and put it into a foaming machine. Introduce air to produce dense foam. Add 0.52kg of 200-mesh elemental iron to 1.2kg of the above powder and mix thoroughly. Mix all the foam into the mixture and add 0.5kg of water. Stir well and place it in a square mold for curing for 3 days. Spray water repeatedly every day and then let it dry naturally. The material changes from brittle to hard, and a phosphorus removal material is obtained. The mass ratio of the matrix material is 72.5%, the mass ratio of elemental iron is 27%, and the mass ratio of plant-based foaming agent is 0.5%.

[0054] Example 3:

[0055] (1) The limestone and clay raw materials are crushed and ground into fine powder, then fired at 1200℃ to form molten small iron balls. These balls are then ground in a grinding mill to achieve a specific surface area of ​​360 m². 2 / kg powder, containing 1.26% LOSS, 20.68% SiO2, 5.6% Al2O3, 3.72% Fe2O3, 55.71% CaO, and 4.63% MgO.

[0056] (2) Prepare 5g of plant-based foaming agent, mix it with 0.25kg of water, stir well, and put it into a foaming machine. Introduce air to produce dense foam. Add 0.5kg of 180-mesh elemental iron to 1.2kg of the above powder and mix thoroughly. Mix all the foam into the mixture and add 0.5kg of water. Stir well and place it in a square mold for curing for 4 days. Spray water repeatedly every day and then let it dry naturally. The material changes from brittle to hard, and a phosphorus removal material is obtained. The mass ratio of the matrix material is 68%, the mass ratio of elemental iron is 31.7%, and the mass ratio of plant-based foaming agent is 0.3%.

[0057] Comparative Example 1:

[0058] The difference between Comparative Example 1 and Example 1 is that no elemental iron is added in Comparative Example 1.

[0059] I. Physical Performance Testing:

[0060] 1. Material Porosity Test: The material porosity was determined through an indoor water saturation test. First, the sample was dried, and its dry mass md was measured. Then, the sample was placed in pure water for saturation treatment, which lasted for 48 hours to ensure complete water saturation. The mass ms of the saturated sample was measured. The porosity p1 of the sample can be calculated using the following formula:

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

[0062] 2. Specific surface area test: The specific surface area of ​​the filler was characterized using the ASAP2020 fully automated specific surface area analyzer from Mack Company, USA.

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

[0064] 4. Pore size: The final pore size of the matrix material is controlled by adjusting the foaming agent content.

[0065] II. Test Results:

[0066] The physical performance parameters of the phosphorus removal materials in the above embodiments and comparative examples are shown in Table 1 after testing.

[0067] Table 1. Physical property parameters of the phosphorus removal materials in the examples and comparative examples.

[0068] 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 shown in Table 1, the phosphorus removal material of the present invention has superior performance compared with the phosphorus removal material of Comparative Example 1, thus achieving excellent phosphorus removal effect.

[0070] Furthermore, 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 subjected to PO4. 3 The phosphorus removal efficiency of a continuous flow device with an influent concentration of 2 mg / L was tested after 75 days of operation, with a conventional phosphorus removal material from Comparative Example 1 used as a control. The test results are as follows: Figure 1 As shown in the figure, the functional filler is the phosphorus removal material of this invention. According to... Figure 1 It can be seen that the phosphorus removal material of the present invention has a significantly higher phosphorus removal capacity than that of Comparative Example 1, with the highest removal capacity of the present invention increased by 25.4%. Furthermore, after 25 days, the material of Comparative Example 1 gradually approached saturation, and its removal capacity decreased, showing a continuous downward trend, while the phosphorus removal material of the present invention maintained a phosphorus removal capacity of approximately 90%. This indicates that the phosphorus removal material of the present invention has a high phosphorus removal effect.

[0071] To test the phosphorus removal material of Example 1 of this invention's removal and tolerance capacity for different phosphorus concentrations, treatment experiments were conducted on wastewater with six different phosphorus concentrations (0.5 mg / L, 1 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L). The conventional phosphorus removal material of Comparative Example 1 was used as a control. The test results are as follows: Figure 2 As shown in the figure, the functional filler is the phosphorus removal material of this invention. Comparison revealed that after 10 days of operation, the phosphorus removal capacity of the material in Comparative Example 1 decreased with increasing phosphorus concentration, and the removal capacity significantly decreased after 30 days of operation. In contrast, the phosphorus removal material of this invention maintained a high removal rate even after increasing concentration, and after 30 days of continuous operation, its phosphorus removal capacity remained at around 80%, significantly better than Comparative Example 1.

[0072] The phosphorus removal material of Example 2 of the present invention was subjected to PO4. 3 The phosphorus removal efficiency of the material was tested after 75 days of operation in a continuous flow apparatus with an influent concentration of 2 mg / L, with a conventional phosphorus removal material (Comparative Example 1) used as a control. Test results showed that the phosphorus removal material of this invention consistently showed an increasing phosphorus removal rate during the first 35 days, reaching 93.82% on day 30, and then trended towards a stable increase, maintaining a phosphorus removal efficiency above 93% after 35 days. In contrast, the conventional packing material (Comparative Example 1) showed a gradual increase in removal efficiency before day 15, reaching 64.73% on day 15, with an overall removal efficiency not exceeding 70%.

[0073] The phosphorus removal material of Example 3 of the present invention was subjected to PO4. 3 The phosphorus removal efficiency of the material was tested after 75 days of operation in a continuous flow apparatus with an influent concentration of 2 mg / L, using a conventional phosphorus removal material as a control. Test results showed that the phosphorus removal material of this invention exhibited a consistent upward trend in the first 29 days, reaching a removal rate of 87.82% on day 29, and then stabilized, maintaining a phosphorus removal efficiency above 89% after 35 days. In contrast, the traditional packing material showed a gradual increase in removal efficiency before day 15, reaching 64.73% on day 15, with an overall removal efficiency not exceeding 70%.

[0074] This demonstrates 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 references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

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

Claims

1. A method for preparing phosphorus removal materials, characterized in that, Includes the following steps: Limestone and clay are mixed and then heat-treated to produce a powder, which is the matrix material. The powder is mixed with elemental iron, a plant-based foaming agent, and water, and then cured to obtain a phosphorus removal material. The mass ratio of the limestone to the clay is (15~16):(4~5). The phosphorus removal material includes: The matrix material includes SiO2, Al2O3, Fe2O3, CaO, and MgO; Elemental iron; Plant-based foaming agent The matrix material comprises 66.5-72.5% by mass, the elemental iron comprises 27-33% by mass, and the plant-based foaming agent comprises 0.1-0.5% by mass.

2. The method according to claim 1, characterized in that, The particle size of the iron element is 150-250 mesh.

3. The method according to claim 1, characterized in that, In the step of mixing the powder with elemental iron, plant-based 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-based foaming agent to the water is 1:(40-60).

4. The method according to claim 1, characterized in that, The specific surface area of ​​the powder is 360~400 m². 2 / kg.

5. The method according to any one of claims 1 to 4, characterized in that, In the step of heat-treating the mixture of limestone and clay, the heat treatment temperature is 1200~1600℃.

6. The application of the phosphorus removal material obtained by the preparation method according to any one of claims 1 to 5 in phosphorus pollution control, including wastewater treatment and rainwater runoff purification.

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