Magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material, preparation method and application thereof
By preparing layered magnesium-aluminum bimetallic oxide-silicon oxide composite materials using cheap mineral raw materials, the problems of rapid release of ordinary fertilizers and the limitations of traditional hydrotalcite materials are solved, and the preparation of efficient slow-release fertilizers and environmentally friendly soil improvement are achieved.
Patent Information
- Application Number
- CN202411592278.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-11-08
AI Technical Summary
Existing ordinary fertilizers release nutrients too quickly and are difficult to control, leading to fertilizer waste and environmental pollution. Traditional hydrotalcite materials in slow-release fertilizer carriers have problems such as low nutrient element loading and difficult to control release rate.
Using cheap and readily available magnesium/aluminum silicate minerals as raw materials, a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material was prepared through a calcination-acid leaching-coprecipitation-hydrothermal-calcination process. It was used as a slow-release fertilizer carrier, and its high specific surface area and developed pore structure were utilized to achieve nutrient loading and slow release.
The preparation process is simple, efficient, low-cost, and suitable for large-scale industrial production. The material has excellent slow-release properties, which can effectively improve fertilizer utilization efficiency, reduce environmental impact, improve soil structure, and provide long-term effective nutrient supply and environmental adaptability.
Smart Images
Figure CN119431052B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of agricultural fertilizers, and in particular to a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material, a preparation method and applications thereof. Background Art
[0002] With the continued rapid growth of the global population and people's increasing expectations for food production and quality, the challenges facing the agricultural sector are becoming increasingly severe. In past agricultural production, the commonly used ordinary fertilizers often had the significant defect of releasing nutrients too quickly and the speed was difficult to control. This means that within a short period of time after fertilization, a large amount of nutrients are rapidly released into the soil, but the crops cannot fully absorb them in time, which not only causes a large amount of waste of precious nutrients in the fertilizer, but also greatly increases the economic cost of agricultural production. What is more serious is that nutrients that are not absorbed by crops enter water bodies and soil through rainwater erosion or soil infiltration, which may cause a series of environmental pollution problems, such as eutrophication of water bodies, soil compaction and acidification, etc., posing a huge threat to ecological balance and sustainable agricultural development. Therefore, the development of a new, efficient and environmentally friendly slow-release fertilizer is of great practical significance.
[0003] As a layered material, hydrotalcite has demonstrated excellent performance in areas such as drug release and pollutant adsorption. Its application in agriculture is primarily focused on its use as a carrier for slow-release pesticides and fertilizers. However, single hydrotalcite materials still have certain limitations in fertilizer carrier applications, such as low nutrient loading and difficulty controlling the release rate. Porous silica has a high specific surface area and a well-developed pore structure. Constructing a composite material of hydrotalcite and porous silica is beneficial for the loading and slow release of nutrients, while also improving soil structure and solidifying soil pollutants. It would be an ideal material for nutrient loading and slow release. Patents CN202410777714.7, CN202310333668.7, CN201611052461.9 and CN201510038720.1 and papers doi.org / 10.1016 / j.jece.2015.05.009, doi.org / 10.1016 / j.micro-meso.2021.111247, doi.org / 10.1021 / acsanm.2c00927, doi.org / 10.1016 / j.micromes-o.2018.09.001 report a variety of hydrotalcite-silica composite materials. These materials are all prepared from high-purity chemical reagents through complex synthesis methods and strict synthesis conditions. They are expensive and are mainly used in high-tech fields such as catalysis and drug sustained release.
[0004] In today's global context of advocating sustainable agricultural development, there is an urgent need for new agricultural slow-release fertilizer materials with a wide range of raw material sources, simple preparation processes, and low production costs. Using abundant and inexpensive magnesium / aluminum silicate minerals as raw materials, a simple conventional process is used to prepare a magnesium-aluminum hydrotalcite-silica composite. This layered magnesium-aluminum bimetallic oxide-silica composite, obtained after calcination, is used as a slow-release fertilizer carrier. This provides an innovative and promising solution to this problem. Summary of the Invention
[0005] In view of the above-mentioned shortcomings that currently exist, the present invention provides a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material, a preparation method and its application. The magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material of the present invention uses cheap and readily available magnesium / aluminum silicate minerals as raw materials, and through conventional synthesis processes, forms a layered magnesium aluminum bimetallic oxide-silicon oxide slow-release fertilizer with high adsorption capacity and good slow-release performance, thereby improving the utilization efficiency of the fertilizer and reducing the impact on the environment.
[0006] In order to achieve the above object, the present invention provides a method for preparing a layered magnesium aluminum bimetallic oxide-silicon oxide composite material derived from a magnesium aluminum silicate mineral, the preparation method comprising the following steps:
[0007] S1. Grinding a silicate mineral into powder and then calcining the powder to obtain an activated silicate mineral; wherein the silicate mineral comprises any one or more of a magnesium silicate mineral, an aluminum silicate mineral, and a magnesium aluminum silicate mineral;
[0008] S2. acid leaching the activated silicate mineral to obtain a solid-liquid mixture A; wherein the solid-liquid mixture comprises insoluble silicon oxide and a leachate;
[0009] S3. Based on the ratio of magnesium to aluminum ions in the hydrotalcite, selectively adding a soluble magnesium salt and / or aluminum salt to the leachate, and stirring to obtain a solid-liquid mixture B; wherein the solid-liquid mixture B comprises insoluble silicon oxide and the regulated leachate;
[0010] It should be noted that the amount of soluble magnesium salt and / or aluminum salt selectively added to the leachate is determined based on the concentration of magnesium and aluminum ions in the solution. (a) If the raw material is a magnesium silicate mineral, the leachate contains more magnesium ions and less aluminum ions, and additional aluminum ions need to be introduced proportionally into the solid-liquid mixture. (b) If the raw material is an aluminum silicate mineral, the leachate contains more aluminum ions and less magnesium ions, and additional magnesium ions need to be introduced proportionally into the solid-liquid mixture. (c) If the raw material contains both magnesium silicate and aluminum silicate or magnesium aluminum silicate minerals, the leachate contains both appropriate magnesium ions and aluminum ions. By controlling the raw material ratio, no additional or only a small amount of aluminum and magnesium ions need to be introduced.
[0011] S4, adjusting the pH value of the solid-liquid mixture B to 9-11, and then performing a hydrothermal reaction to synthesize a magnesium-aluminum hydrotalcite-silicon oxide composite material;
[0012] It should be noted that the purpose of adjusting the pH value of the solid-liquid mixture B is to promote the co-precipitation of magnesium and aluminum.
[0013] S5. The magnesium aluminum hydrotalcite-silicon oxide composite material is subjected to solid-liquid separation, drying, and then calcining to obtain a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material.
[0014] Furthermore, in step S1, the temperature of the calcination treatment is 600-1000° C., and the time of the calcination treatment is 0.5-3 hours.
[0015] Furthermore, in step S1, the magnesium silicate mineral includes any one or more of serpentine, talc, and sepiolite; the aluminum silicate mineral includes one or more of pyrophyllite, kaolinite, halloysite, illite, and muscovite; the magnesium aluminum silicate mineral includes one or more of montmorillonite, palygorskite, vermiculite, chlorite, rectorite, and phlogopite.
[0016] Furthermore, in step S2, the solid-liquid ratio of the activated silicate mineral to the acid is 1:10-1:60, the acid used for acid leaching is sulfuric acid or hydrochloric acid, the concentration of the sulfuric acid or hydrochloric acid is 0.5-4.0 mol / L, the leaching temperature of the acid leaching is 30-80°C, and the leaching time of the acid leaching is 0.5-5h.
[0017] Furthermore, in step S3, the molar ratio of magnesium to aluminum ions in the regulated leachate is 2:1-4:1, the concentration of magnesium ions in the regulated leachate is 1-16 g / L, and the concentration of aluminum ions in the regulated leachate is 0.5-8 g / L.
[0018] Furthermore, in step S4, the substance for adjusting the pH value of the solid-liquid mixture B is a mixed solution of sodium carbonate and sodium hydroxide; wherein the concentration of the sodium carbonate is 0.1-0.2 mol / L, and the concentration of the sodium hydroxide is 1.0-2.0 mol / L.
[0019] Furthermore, in step S4, the temperature of the hydrothermal reaction is 40-80° C., and the time of the hydrothermal reaction is 12-48 hours.
[0020] Furthermore, in step S5, the temperature of the calcination treatment is 400-800° C., and the time of the calcination treatment is 0.5-3 hours.
[0021] Based on the same inventive concept, the present invention also provides a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material prepared by any of the above preparation methods.
[0022] Based on the same inventive concept, the present invention also provides the use of the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material prepared by any of the above preparation methods in fertilizer slow release.
[0023] Furthermore, the fertilizer is specifically a layered magnesium-aluminum bimetallic oxide-silicon oxide-based nitrogen fertilizer, phosphate fertilizer, selenium fertilizer and compound slow-release fertilizer. The preparation method of the layered magnesium-aluminum bimetallic oxide-silicon oxide-based nitrogen fertilizer, phosphate fertilizer, selenium fertilizer and compound slow-release fertilizer is: adding the layered magnesium-aluminum bimetallic oxide-silicon oxide composite material to a single nutrient solution or a compound nutrient solution of nitrogen, phosphorus and selenium, and preparing the fertilizer after impregnation, adsorption and drying.
[0024] Furthermore, the single nutrient solution or compound nutrient solution of nitrogen, phosphorus and selenium includes but is not limited to any one or more soluble salts of potassium nitrate, ammonium nitrate, potassium phosphate, ammonium dihydrogen phosphate, sodium selenate and sodium selenite.
[0025] Furthermore, the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material is immersed and adsorbed in the above-mentioned single nutrient solution or composite nutrient solution with various soluble salt concentrations of 1-10 g / L for 12-48 hours.
[0026] Beneficial effects of the present invention:
[0027] (1) The preparation method of layered magnesium-aluminum bimetallic oxide-silicon oxide composite material has advantages and innovations: The present invention adopts the process of calcination-acid leaching-coprecipitation-hydrothermal-calcination to successfully transform magnesium / aluminum silicate minerals into layered magnesium-aluminum bimetallic oxide-silicon oxide composite materials with high specific surface area and developed pore structure. Among them, calcination-acid leaching can efficiently extract magnesium, aluminum and other elements in the minerals and form porous silica, coprecipitation-hydrothermal can prepare magnesium-aluminum ions and porous silica into magnesium-aluminum hydrotalcite-silicon oxide composite materials, and calcination can effectively transform magnesium-aluminum hydrotalcite-silicon oxide composite materials into layered magnesium-aluminum bimetallic oxide-silicon oxide composite materials. Multiple conventional processes work together to efficiently activate and transform mineral components, thereby forming a composite material with excellent performance. The entire preparation process is simple and efficient to operate, with low equipment requirements, and is very suitable for large-scale industrial production, with higher economic benefits and stronger market competitiveness.
[0028] (2) The raw materials for the preparation of layered magnesium aluminum bimetallic oxide-silicon oxide composite materials have advantages and innovations: The present invention uses serpentine, talc, sepiolite, pyrophyllite, kaolinite, halloysite, illite, muscovite, montmorillonite, palygorskite, vermiculite, chlorite, rectorite, phlogopite and other low-priced and easily accessible magnesium silicate minerals, aluminum silicate minerals, and magnesium aluminum silicate minerals as raw materials. These raw materials break through the limitations of using high-purity chemical products as raw materials in traditional synthesis methods, and provide a new idea for large-scale, low-cost production of high-performance composite materials. Compared with high-purity, high-cost chemical products, magnesium / aluminum silicate minerals as raw materials have significant advantages. They are abundant in reserves, widely distributed, low in cost, easy to obtain, and have strong substitutability, effectively reducing raw material costs and supply risks.
[0029] (3) The preparation and application of slow-release fertilizers have advantages and innovations: The present invention uses a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material as a slow-release fertilizer carrier. The composite material has different levels and complex interlayer structures, pore structures, inter-particle structures, and surface structures, which can allow nutrients to be adsorbed, attached, filled, and coated to different degrees at different positions therein, and have different desorption and release rates. Therefore, the fertilizer can be efficiently loaded on the composite material through the impregnation adsorption method, and the nutrients can be slowly released in the soil through the difference in the difficulty of nutrient release at different positions in the material. It has long-term effectiveness and environmental adaptability, and the process is simple and the performance is stable, which has obvious advantages in large-scale production. In addition, the slow decomposition and release of bimetallic hydroxides and silicon oxide in the slow-release fertilizer can supply the necessary magnesium and silicon elements for plant growth, showing significant innovation in material application. In addition, at the soil improvement level, the material can enhance the soil's water and fertilizer retention capacity, regulate soil pH, promote microbial activity, and reduce heavy metal pollution, thereby creating favorable conditions for crop growth and effectively ensuring the quality and safety of agricultural products.
[0030] In summary, the present invention demonstrates significant advantages in terms of material innovation, slow-release control, environmental friendliness, and economic benefits, and provides a new method and material for the development of slow-release fertilizers. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is a flow chart for preparing the composite slow-release fertilizer based on the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material of the present invention;
[0032] Figure 2 These are SEM images of the magnesium aluminum silicate mineral-derived layered bimetallic oxide-silicon oxide composite materials described in Examples 1-6 of the present invention; wherein: (a) serpentine LDO@Si; (b) talc LDO@Si; (c) kaolin LDO@Si; (d) halloysite LDO@Si; (e) vermiculite LDO@Si; and (f) chlorite LDO@Si.
[0033] Figure 3 The loading capacity of the layered magnesium aluminum bimetallic oxide-silicon oxide composite material prepared in Examples 1-6 of the present invention for nitrate, selenite and phosphate;
[0034] Figure 4 The hydrostatic release curves of the layered magnesium-aluminum bimetallic oxide-silicon oxide-based slow-release nitrogen fertilizers prepared in Examples 1-6 of the present invention;
[0035] Figure 5 The hydrostatic release curves of the layered magnesium-aluminum bimetallic oxide-silicon oxide-based slow-release phosphate fertilizers prepared in Examples 1-6 of the present invention are shown;
[0036] Figure 6 The hydrostatic release curves of the layered magnesium-aluminum bimetallic oxide-silicon oxide-based slow-release selenium fertilizers prepared in Examples 1-6 of the present invention are shown. DETAILED DESCRIPTION
[0037] To make the present invention easier to understand, the present invention is further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in this field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.
[0038] Example 1
[0039] A method for preparing a slow-release fertilizer based on a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material derived from magnesium-aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0040] In this embodiment, serpentine is used as the source of Mg and silicon oxide, and the contents of Mg and Si are 23.17% and 19.40% respectively.
[0041] After the serpentine is ground into powder, it is calcined at 600°C for 0.5h. The calcined serpentine is added to a 2mol / L hydrochloric acid solution at a solid-liquid ratio of 1:60, and stirred and leached at 40°C for 2h to obtain a solid-liquid mixture with a magnesium ion concentration of about 3.8g / L; aluminum salt is added to the mixed solution at a magnesium-aluminum molar ratio of 2:1 and stirred evenly; a mixed solution of 0.2moL / L sodium carbonate and 2.0mol / L sodium hydroxide is slowly added to the above mixture to adjust the pH to 9.5; the solid-liquid mixture is then hydrothermally synthesized at 60°C for 24h to prepare magnesium-aluminum hydrotalcite-oxygen The prepared serpentine LDH@Si was subjected to solid-liquid separation and drying, and then calcined at 450°C for 1.5h to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide composite material (serpentine LDO@Si); the serpentine LDO@Si was added to a 1g / L potassium nitrate, 3g / L sodium selenite and 5g / L potassium phosphate composite solution at a solid-liquid ratio of 1:100, and the mixture was immersed and adsorbed for 24h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide based composite slow-release fertilizer (CRSF). Figure 2 (a) SEM image shows that the flake oxide is successfully grown on the silicon oxide surface; Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 8.27 mg / g, 122.31 mg / g, and 50.94 mg / g, respectively. Figure 4-6 As shown in the results, under static water conditions, 77.43% of N and 62.69% of Se were released within 120 h, while 51.36% of P was released within 240 h, showing excellent sustained-release performance.
[0042] Example 2
[0043] A method for preparing a slow-release fertilizer based on a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material derived from magnesium-aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0044] In this embodiment, talc is used as the source of Mg and silicon oxide, and the contents of Mg and Si are 19% and 29.5% respectively.
[0045] After the talc is ground into powder, it is calcined at 700°C for 2.0h. The calcined talc is added to a 0.5mol / L sulfuric acid solution at a solid-liquid ratio of 1:20, stirred and leached at 30°C for 5h to obtain a solid-liquid mixture with a magnesium ion concentration of about 9.0g / L; aluminum salt is added to the mixed solution at a magnesium-aluminum molar ratio of 3:1 and stirred evenly; a mixed solution of 0.2moL / L sodium carbonate and 2.0mol / L sodium hydroxide is slowly added to the above mixture to adjust the pH to 9.0; the solid-liquid mixture is then hydrothermally synthesized at 80°C for 24h to prepare magnesium-aluminum hydrotalcite. Talc-silicon oxide composite material (talc LDH@Si); after solid-liquid separation and drying of the prepared talc LDH@Si, calcined at 500°C for 1.5h to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide composite material (talc LDO@Si); talc LDO@Si was added to a 2g / L potassium nitrate, 5g / L sodium selenite and 8g / L potassium phosphate composite solution at a solid-liquid ratio of 1:100, immersed and adsorbed for 48h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide based composite slow-release fertilizer (CRSF). Figure 2 (b) SEM shows that the oxide nanosheets are cross-linked to form a layered structure. Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 13.56 mg / g, 172.67 mg / g, and 68.69 mg / g, respectively. Figure 4-6 As shown in the results, under static water conditions, 76.34% of N and 63.06% of Se were released within 120 h, while 47.2% of P was released within 240 h, showing excellent sustained-release performance.
[0046] Example 3
[0047] A method for preparing a slow-release fertilizer based on a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material derived from magnesium-aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0048] In this embodiment, kaolin is used as the source of Al and silicon oxide, and the Al and Si contents are 23.93% and 21.71% respectively.
[0049] After kaolin is ground into powder, it is calcined at 800°C for 1.5 hours. The calcined kaolin is added to a 0.5 mol / L sulfuric acid solution at a solid-liquid ratio of 1:40, and stirred and leached at 60°C for 3 hours to obtain a solid-liquid mixture with an aluminum ion concentration of about 5.6 g / L; magnesium salt is added to the mixed solution at a magnesium-aluminum molar ratio of 2:1 and stirred evenly; a mixed solution of 0.2 mol / L sodium carbonate and 2.0 mol / L sodium hydroxide is slowly added to the above mixture to adjust the pH to 10.0; the solid-liquid mixture is then hydrothermally synthesized at 40°C for 24 hours to prepare magnesium-aluminum hydrotalcite- Silica composite material (kaolin LDH@Si); after solid-liquid separation and drying of the prepared kaolin LDH@Si, calcination at 550°C for 2.0h obtains a layered magnesium aluminum bimetallic oxide-silica composite material (kaolin LDO@Si); kaolin LDO@Si is added to a composite solution of 3g / L potassium nitrate, 10g / L sodium selenite and 10g / L potassium phosphate at a solid-liquid ratio of 1:100, immersed and adsorbed for 36h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silica-based composite slow-release fertilizer (CRSF). Figure 2 (c) SEM image shows that the oxide nanosheet structure is formed on the surface of silicon oxide; Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 7.38 mg / g, 112.44 mg / g, and 56.94 mg / g, respectively. Figure 4-6 As shown in the results, under static water conditions, 56.89% of N and 58.16% of Se were released within 120 h, while 46.68% of P was released within 240 h, showing excellent sustained-release performance.
[0050] Example 4
[0051] A method for preparing a slow-release fertilizer based on a layered bimetallic oxide-silicon oxide composite material derived from magnesium aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0052] In this embodiment, halloysite is used as the source of Al and silicon oxide, and the Al and Si contents are approximately 22.6% and 23.5%, respectively.
[0053] After the halloysite is ground into powder, it is calcined at 850°C for 3 hours. The calcined halloysite is added to a 1 mol / L sulfuric acid solution at a solid-liquid ratio of 1:30, and stirred and leached at 80°C for 3 hours to obtain a solid-liquid mixture with an aluminum ion concentration of about 7.1 g / L; magnesium salt is added to the mixed solution at a magnesium-aluminum molar ratio of 2:1, and stirred evenly; 0.2 mol / L sodium carbonate and 2.0 mol / L sodium hydroxide mixed solution is slowly added to the above mixture to adjust the pH to 9.0; the solid-liquid mixture is then hydrothermally synthesized at 80°C for 24 hours to prepare magnesium-aluminum hydrotalcite-oxide. Silicon composite material (halloysite LDH@Si); after the prepared halloysite LDH@Si is subjected to solid-liquid separation and drying, it is calcined at 600°C for 1.0h to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide composite material (halloysite LDO@Si); the halloysite LDO@Si is added to a 1g / L potassium nitrate, 3g / L sodium selenite and 5g / L potassium phosphate composite solution at a solid-liquid ratio of 1:100, and the mixture is immersed and adsorbed for 12h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide based composite slow-release fertilizer (CRSF). Figure 2 (d) SEM shows that oxide nanosheet structures are formed on the surface of silicon oxide; Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 15.34 mg / g, 183.58 mg / g, and 72.94 mg / g, respectively. Figure 4-6 As shown in the data, under static water conditions, 63.46% of N and 58.49% of Se were released within 120 h, while 43.57% of P was released within 240 h, showing excellent sustained-release performance.
[0054] Example 5
[0055] A method for preparing a slow-release fertilizer based on a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material derived from magnesium-aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0056] In this embodiment, vermiculite is used as the source of Mg, Al and silicon oxide, and the contents of Mg, Al and Si are 13.2%, 6.51% and 15.86% respectively.
[0057] After vermiculite is ground into powder, it is calcined at 900°C for 1.5 hours. The calcined vermiculite is added to a 1 mol / L sulfuric acid solution at a solid-liquid ratio of 1:20, and stirred and leached at 60°C for 3 hours to obtain a solid-liquid mixture with a magnesium ion concentration of about 6.1 g / L and an aluminum ion concentration of about 3.0 g / L, and a magnesium-aluminum molar ratio of about 2.3:1; 0.2 mol / L sodium carbonate and 2.0 mol / L sodium hydroxide mixed solution are slowly added to the above mixture to adjust the pH to 9.0; the solid-liquid mixture is then hydrothermally synthesized at 60°C for 36 hours to prepare magnesium-aluminum hydrotalcite-oxygen Silicon composite material (vermiculite LDH@Si); after the prepared vermiculite LDH@Si is subjected to solid-liquid separation and drying, it is calcined at 650°C for 0.5h to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide composite material (vermiculite LDO@Si); vermiculite LDO@Si is added to 1g / L potassium nitrate, 3g / L sodium selenite and 5g / L potassium phosphate composite solution at a solid-liquid ratio of 1:100, immersed and adsorbed for 36h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide based composite slow-release fertilizer (CRSF). Figure 2 (e) SEM image shows that oxide nanosheet structure is formed on the surface of silicon oxide; Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 8.75 mg / g, 117.91 mg / g, and 58.26 mg / g, respectively. Figure 4-6 As shown in the results, under static water conditions, 70.89% of N and 69.10% of Se were released within 120 h, while 66.32% of P was released within 240 h, showing excellent sustained-release performance.
[0058] Example 6
[0059] A method for preparing a slow-release fertilizer based on a layered magnesium-aluminum bimetallic oxide-silicon oxide composite material derived from magnesium-aluminum silicate minerals, the preparation process of which is as follows: Figure 1 As shown:
[0060] In this embodiment, chlorite is used as the source of Mg, Al and silicon oxide, and the contents of Mg, Al and Si are 18.32%, 6.87% and 18.78% respectively.
[0061] After the chlorite is ground into powder, it is calcined at 1000°C for 0.5h. The calcined chlorite is added to a 1mol / L sulfuric acid solution at a solid-liquid ratio of 1:20, and stirred and leached at 60°C for 2h to obtain a solid-liquid mixture with a magnesium ion concentration of about 8.6g / L and an aluminum ion concentration of about 3.2g / L, and a magnesium-aluminum molar ratio of about 3:1; 0.2mol / L sodium carbonate and 2.0mol / L sodium hydroxide mixed solution are slowly added to the above mixture to adjust the pH to 11.0; the solid-liquid mixture is then hydrothermally synthesized at 80°C for 48h to prepare magnesium-aluminum hydrotalcite-silica. Composite material (chlorite LDH@Si); after the prepared chlorite LDH@Si is subjected to solid-liquid separation and drying, it is calcined at 550°C for 1.5h to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide composite material (chlorite LDO@Si); chlorite LDO@Si is added to a 1g / L potassium nitrate, 3g / L sodium selenite and 5g / L potassium phosphate composite solution at a solid-liquid ratio of 1:100, immersed and adsorbed for 36h and then dried to obtain a layered magnesium aluminum bimetallic oxide-silicon oxide based composite slow-release fertilizer (CRSF). Figure 2 (f) SEM image shows that oxide nanosheet structure is formed on the surface of silicon oxide; Figure 3 It can be seen that the loading amounts of N, Se, and P elements are 6.18 mg / g, 101.88 mg / g, and 52.83 mg / g, respectively. Figure 4-6 As shown in the data, under static water conditions, 68.89% of N and 66.70% of Se were released within 120 h, while 50.49% of P was released within 240 h, showing excellent sustained-release performance.
[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.
Claims
1. A method for preparing a layered magnesium aluminum bimetallic oxide-silicon oxide composite material derived from magnesium aluminum silicate minerals, characterized in that: The preparation method comprises the following steps: S1. Grinding a silicate mineral into a powder and then calcining it to obtain an activated silicate mineral; wherein the silicate mineral includes any one or more of a magnesium silicate mineral, an aluminum silicate mineral, and a magnesium aluminum silicate mineral; wherein the calcination temperature is 600-1000° C., and the calcination time is 0.5-3 h; the magnesium silicate mineral includes any one or more of serpentine, talc, and sepiolite; the aluminum silicate mineral includes one or more of pyrophyllite, kaolinite, halloysite, illite, and muscovite; the magnesium aluminum silicate mineral includes one or more of montmorillonite, palygorskite, vermiculite, chlorite, rectorite, and phlogopite; S2. Acid leaching the activated silicate mineral to obtain a solid-liquid mixture A; wherein the solid-liquid mixture comprises insoluble silicon oxide and a leachate; wherein the solid-liquid ratio of the activated silicate mineral to the acid is 1:10-1:60, the acid used for the acid leaching is sulfuric acid or hydrochloric acid, the concentration of the sulfuric acid or hydrochloric acid is 0.5-4.0 mol / L, the leaching temperature of the acid leaching is 30-80° C., and the leaching time of the acid leaching is 0.5-5 h; S3. Based on the ratio of magnesium to aluminum ions in the hydrotalcite, selectively adding a soluble magnesium salt and / or aluminum salt to the leachate, and stirring to obtain a solid-liquid mixture B; wherein the solid-liquid mixture B comprises insoluble silicon oxide and the regulated leachate; S4, adjusting the pH value of the solid-liquid mixture B to 9-11, and then performing a hydrothermal reaction to synthesize a magnesium-aluminum hydrotalcite-silicon oxide composite material; S5. The magnesium aluminum hydrotalcite-silicon oxide composite material is subjected to solid-liquid separation, drying, and then calcining to obtain a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material.
2. The method for preparing the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material according to claim 1, characterized in that: In step S3, the molar ratio of magnesium to aluminum ions in the regulated leachate is 2:1-4:1, the concentration of magnesium ions in the regulated leachate is 1-16 g / L, and the concentration of aluminum ions in the regulated leachate is 0.5-8 g / L.
3. The method for preparing the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material according to claim 1, characterized in that: In step S4, the substance for adjusting the pH value of the solid-liquid mixture B is a mixed solution of sodium carbonate and sodium hydroxide; wherein the concentration of the sodium carbonate is 0.1-0.2 mol / L, and the concentration of the sodium hydroxide is 1.0-2.0 mol / L.
4. The method for preparing the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material according to claim 1, characterized in that: In step S4, the temperature of the hydrothermal reaction is 40-80° C., and the time of the hydrothermal reaction is 12-48 h.
5. The method for preparing the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material according to claim 1, characterized in that: In step S5, the calcination temperature is 400-800° C., and the calcination time is 0.5-3 h.
6. A magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material prepared by the preparation method according to any one of claims 1 to 5.
7. Use of a magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material prepared by the preparation method according to any one of claims 1 to 5 or the magnesium aluminum silicate mineral-derived layered magnesium aluminum bimetallic oxide-silicon oxide composite material according to claim 6 in a fertilizer slow-release, characterized in that: The fertilizers are specifically layered magnesium-aluminum bimetallic oxide-silicon oxide-based nitrogen fertilizers, phosphate fertilizers, selenium fertilizers and compound slow-release fertilizers. The preparation method of the layered magnesium-aluminum bimetallic oxide-silicon oxide-based nitrogen fertilizers, phosphate fertilizers, selenium fertilizers and compound slow-release fertilizers is as follows: the layered magnesium-aluminum bimetallic oxide-silicon oxide composite material is added to a single nutrient solution or a compound nutrient solution of nitrogen, phosphorus and selenium, and the mixture is prepared after impregnation, adsorption and drying.