A precise controlled release membrane material with directional pore construction and its preparation method and application

Abstract

The present invention discloses a precise controlled release membrane material with pore-oriented construction and its preparation method and application, which belongs to the technical field of controlled release fertilizer production. The precise controlled release membrane material with pore-oriented construction of the present invention is made of the following raw materials in parts by weight: 100 parts of bio-based controlled release material and 0.1-3 parts of modifier; the modifier is a composite material obtained by modifying MOF material with a group-modified material; the group-modified material is selected from one or more of polydimethylsiloxane, n-heptane, ethyl silicate, amino acid, iron oxide, ferrous sulfate, methanesulfonic acid, and polyvinyl alcohol. The present invention uses metal-organic framework materials and group-modified materials to modify bio-based controlled release membrane materials, and uses the self-assembly and spatial topological structure of metal-organic framework materials to construct pores in a directional manner, thereby achieving precise controlled release of nutrients.

Description

Technical Field

[0001] The present invention relates to the technical field of controlled-release fertilizer production, and in particular to a precise controlled-release membrane material with directional pore construction, and a preparation method and application thereof. Background Art

[0002] Coated controlled-release fertilizers have the advantages of high efficiency, labor saving, and fertilizer saving, but the coating materials of controlled-release fertilizers are mainly petrochemical products, and there are problems such as high cost, non-renewable resources, and difficult degradation. Therefore, low-cost, renewable, and environmentally friendly green bio-based controlled-release membrane materials have become the development direction of this industry, but most bio-based membrane materials are hydrophilic, loose and porous, with poor controlled-release quality. The nutrient release does not match the fertilizer requirements of crops, and it is impossible to achieve the precise release of nutrients from slow-release fertilizers. This is because the bio-based membrane material is similar to a semi-permeable membrane. Water enters the membrane through the membrane pores in the membrane shell, dissolves nutrients, and forms osmotic pressure. Nutrients can be released from the membrane pores, but can only be released passively and cannot be accurately controlled according to crop needs, resulting in a waste of some nutrients.

[0003] Under certain conditions, the size of the osmotic pressure is related to the size and number of membrane pores and the temperature. However, the disadvantage of the current controlled-release fertilizer is that the size of the membrane pores is fixed and cannot be adjusted, so its release is a gradual release and cannot be adjusted. The current ways to regulate nutrient release are: one is to change the thickness to adjust the size and number of pores; the other is to add open-pore substances, such as calcium carbonate, montmorillonite, etc. to increase the size and number of pores, thereby regulating the release. However, the above methods are one-time irreversible regulation methods, and it is difficult to achieve precise regulation.

[0004] Metal-organic framework (MOF) materials refer to crystalline porous materials with periodic network structures formed by self-assembly of transition metal ions and organic ligands. They are new functional materials that have received extensive attention and research in recent years. Since there are many possibilities for the combination of metals or metal clusters and organic ligands, the structure and performance of the materials are also diverse. The pore size, specific surface area, and redox sites of the materials can be improved by changing different reaction conditions. Therefore, the application of MOF materials in gas adsorption and separation, catalysis, biomedicine and other fields has received extensive attention.

[0005] Compared with other fields, the application research of MOF materials in the agricultural field is obviously insufficient. At present, the application of MOF materials in slow-release fertilizers is mainly: using ferric chloride, zinc sulfate, phosphoric acid, oxalic acid and urea as substrates, by adjusting the substrate molar ratio, reaction temperature and reaction time, a series of OA-MOFs can be synthesized under hydrothermal conditions. Metal ions, phosphoric acid and oxalic acid constitute the external skeleton of OA-MOF, and urea is hydrolyzed into ammonium nitrogen and embedded in the skeleton. OA-MOF not only has high nutrient content and diverse types, but also has slow-release function (Metal Organic Framework (MOF) Materials and Their Applications in New Slow-Release Fertilizers, Journal of Huazhong Agricultural University, Vol. 41, No. 2, March 2022). However, there is no report on the direct use of MOF materials to modify the coating material to achieve precise controlled release of nutrients. Summary of the invention

[0006] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a precise controlled release membrane material with directional pore construction and its preparation method and application. The present invention uses metal organic framework materials and group modified materials to modify the bio-based controlled release membrane material, and uses the self-assembly and spatial topological structure of the metal organic framework material to directional construct pores, thereby achieving precise controlled release of nutrients.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect of the present invention, there is provided a precise controlled release membrane material with directional pore construction, which is made of the following raw materials in parts by weight:

[0009] 100 parts of bio-based controlled release material, 0.1-3 parts of modifier;

[0010] The modifier is a composite material obtained by modifying the MOF material with a group-modifying material; the group-modifying material is selected from one or more of polydimethylsiloxane, n-heptane, ethyl silicate, amino acid, iron oxide, ferrous sulfate, methanesulfonic acid, and polyvinyl alcohol.

[0011] Preferably, the weight ratio of the MOF material to the group-modified material is (0.1-1):(0.5-1.5).

[0012] Preferably, the bio-based controlled-release material is one or more of bio-based acrylamide resin, bio-based isothiocyanate, and bio-based polyurethane.

[0013] Preferably, the modifier is one or more of a ZIF-8 (Zn) composite material, a HKUST1 (Cu) composite material, and a MOF-303 (Al) composite material.

[0014] More preferably, the ZIF-8(Zn) composite material is prepared by the following method:

[0015] The ZIF-8, polydimethylsiloxane, n-heptane and ethyl silicate were mixed, ultrasonicated for 20-40 minutes, and dried to prepare a ZIF-8 (Zn) composite material.

[0016] ZIF-8 was modified with polydimethylsiloxane, n-heptane and ethyl silicate. Firstly, the hydrophobicity of ZIF-8 was increased, thus improving the controlled release performance of the membrane. Secondly, the modified groups were grafted so that MOF could self-assemble, spontaneously arrange and combine in a directional manner, thus realizing the directional construction of pores.

[0017] More preferably, the HKUST1(Cu) composite material is prepared by the following method:

[0018] After HKUST-1 is fully mixed with the amino acid solution, ferric chloride and ferrous sulfate, it is ultrasonicated for 2.5-3.5 hours in a nitrogen atmosphere, centrifuged to obtain a precipitate, and dried to prepare a HKUST1(Cu) composite material.

[0019] Modification of HKUST-1 with amino acid solution, ferric chloride and ferrous sulfate can increase the magnetism of HKUST1 material. Under the action of magnetic field, it can also achieve directional combination and arrangement, adjust the stability of the modifier and its autonomous directional construction ability, and increase the adsorption capacity.

[0020] More preferably, the MOF-303 (Al) composite material is prepared by the following method:

[0021] MOF-303 was immersed in a methanol solution containing methanesulfonic acid, stirred for 10-14 hours, and dried to obtain MeSA@MOF303; MeSA@MOF303 was dispersed in deionized water, polyvinyl alcohol was added, and stirred at 90-100°C to obtain a uniform suspension, which was centrifuged and dried to prepare a MOF-303(Al) composite material.

[0022] Surface modification of MOF-303 using methanesulfonic acid and polyvinyl alcohol can improve the stability and hydrophobicity of the MOF surface.

[0023] The second aspect of the present invention provides the use of the above-mentioned precise controlled release membrane material in the preparation of controlled release fertilizers.

[0024] The third aspect of the present invention provides a coated controlled-release fertilizer, comprising a fertilizer core and a precise controlled-release film material sprayed on the surface of the fertilizer core; the precise controlled-release film material accounts for 1-5% of the weight of the fertilizer core.

[0025] A fourth aspect of the present invention provides a method for preparing the above-mentioned coated controlled-release fertilizer, comprising the following steps:

[0026] Preheat the fertilizer core to 50-60℃, then spray the precision controlled release membrane material on the surface of the fertilizer core and cure it for 5-10 minutes.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention utilizes different types of metal organic framework compounds to modify them, and utilizes the self-assembly and spatial topological structure of the metal organic framework compounds to directionally construct pores. The fertilizer nutrient release pores can be adjusted by different MOF types and different addition amounts, thereby achieving precise nutrient release.

[0029] (2) The membrane shell prepared by the present invention contains trace elements, which can add nutrition to crops, increase yield, reduce harm to the environment, and have good economic and social benefits.

[0030] (3) The modified material synthesis method of the present invention is simple and easy to obtain, and the reaction conditions are relatively mild, which is conducive to large-scale production, lays a foundation for industrialization, and is conducive to promoting the further development of the slow-release fertilizer industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : Transmission electron microscopy (TEM) image of the MOF-303 material prepared in Example 1.

[0032] Figure 2 : EDS element scanning analysis diagram of the MOF-303 material prepared in Example 1; the left figure is the scanning distribution of the Al element, and the right figure is the scanning distribution of the C element.

[0033] Figure 3 : Photos of the precise controlled release membranes prepared in Examples 1 to 3 and the unmodified bio-based coating fluid of Comparative Example 1 after curing.

[0034] Figure 4 : Photos of the modified bio-based coated controlled-release fertilizers prepared in Examples 4 to 6 and the unmodified bio-based coated controlled-release fertilizer prepared in Comparative Example 1.

[0035] Figure 5 : Infrared spectrum analysis diagram of the modified bio-based coated controlled-release fertilizer membrane shell prepared in Example 4.

[0036] Figure 6 : Scanning electron micrograph of the bio-based coated controlled-release fertilizer membrane shell prepared in Example 4 and Comparative Example 1.

[0037] Figure 7 : X-ray photoelectron spectroscopy analysis diagram of the modified bio-based coated controlled-release fertilizer membrane shell prepared in Example 4.

[0038] Figure 8: Nutrient release diagram of the controlled-release fertilizers prepared in Examples 4-6 and Comparative Example 1 within the first 30 days; in the figure, unmodified refers to the controlled-release fertilizer prepared in Comparative Example 1, 0.5% modified refers to the controlled-release fertilizer prepared in Example 5, 1% modified refers to the controlled-release fertilizer prepared in Example 4, and 1.5% modified refers to the controlled-release fertilizer prepared in Example 6.

[0039] Fig. 9 : Nutrient release curves of the controlled-release fertilizer prepared in Example 4 and the controlled-release fertilizer prepared in Comparative Example 1 are compared with crop demand; in the figure, unmodified refers to the controlled-release fertilizer prepared in Comparative Example 1, and modified refers to the controlled-release fertilizer prepared in Example 4. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0041] As mentioned above, the application research of MOF materials in the agricultural field is obviously insufficient. The main reasons are: first, as an emerging material, MOF has many functions that need to be further explored and explored; second, there is insufficient cross-disciplinary integration, and the application is difficult. The application of MOF materials in controlled-release fertilizers is mainly to use its framework structure to carry and store nutrients to achieve slow release of nutrients. However, there are few reports on the application of MOF materials in the modification of coating materials.

[0042] In order to solve the above problems, the present invention takes bio-based controlled release membrane as the basis, adds different types of metal organic framework compounds and group modification materials to modify it, utilizes the self-assembly and spatial topological structure of the metal organic framework compounds to directionally construct pores, and constructs a new type of membrane material with controllable pores to achieve precise controlled release, thereby realizing adjustable nutrient release.

[0043] The MOF material used in the present invention is selected from one or more of ZIF-8, HKUST1, and MOF-303. The group modification material is selected from one or more of polydimethylsiloxane, n-heptane, ethyl silicate, amino acid, iron oxide, ferrous sulfate, methanesulfonic acid, and polyvinyl alcohol.

[0044] The present invention uses group modification materials to modify MOF materials. By grafting groups, the hydrophobicity and stability of MOF materials can be improved, and the ability of MOF materials to directional construction can be enhanced. The modified MOF materials are used to modify bio-based controlled release membrane materials, which can significantly improve the controlled release performance of the membrane materials.

[0045] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0046] The test materials used in the examples and comparative examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0047] Example 1: Preparation of a precise controlled release membrane with directional pore construction

[0048] 1. Preparation of MOF materials:

[0049] 0.6 g of 3,5-pyrazoledicarboxylic acid, 0.9 g of aluminum chloride hexahydrate, and 0.3 g of sodium hydroxide were dissolved in 135 g of deionized water, placed in a hydration reactor and reacted at 80° C. for 24 hours, and solid MOF-303 was obtained after centrifugal drying.

[0050] 2. Modification of MOF materials:

[0051] 1.2 g of the prepared solid MOF-303 was immersed in a methanol solution containing 1.2 g of methanesulfonic acid (MeSA), stirred at room temperature for 12 h, and placed in a vacuum oven at 60 °C for 8 h to obtain MeSA@MOF303.

[0052] 1 g MeSA@MOF-303 was completely dispersed in 17 mL deionized water by ultrasound, 3 g polyvinyl alcohol (PVA) was added, and the mixture was stirred at 95 °C to obtain a uniform suspension. After centrifugation, the supernatant was poured out, the solid was collected and vacuum dried, and the powder was collected to obtain a MOF-303 (Al) composite material.

[0053] 3. Preparation of precise controlled release membrane:

[0054] Take 25g of 4-methoxyphenyl isothiocyanate and 25g of castor oil (CAS No. 8001-79-4) as bio-based controlled release materials; add 0.5g of MOF-303 (Al) composite material to the bio-based controlled release material, stir evenly until completely dissolved, and prepare a precise controlled release membrane material with directional pore structure.

[0055] Example 2: Preparation of a precise controlled release membrane with directional pore construction

[0056] 1. Preparation of MOF materials:

[0057] At 50°C, 1 g of 1,3,5-benzenetricarboxylic acid and 0.2 g of indoleacetic acid were dissolved in 40 ml of a mixed solution of water / ethanol / N,N-dimethylformamide (1:1:1, volume ratio), and ultrasonically dispersed for 10 minutes to prepare solution 1; 1.1 g of copper nitrate trihydrate was dissolved in 20 ml of a mixed solution of water / ethanol / N,N-dimethylformamide (1:1:1), and ultrasonically dispersed for 10 minutes to prepare solution 2; solution 1 and solution 2 were mixed, kept at 85°C for 24 hours, and then taken out to obtain a precipitate, which was washed and vacuum dried to obtain the HKUST1 material.

[0058] 2. Modification of MOF materials:

[0059] The HKUST1 material obtained above was fully mixed with 20 ml of 10% by volume arginine solution, 20 ml of iron oxide, and 20 ml of ferrous sulfate, ultrasonicated for 3 hours under a nitrogen atmosphere, centrifuged to obtain a precipitate, and then freeze-dried to obtain a HKUST1 (Cu) composite material.

[0060] 3. Preparation of precise controlled release membrane:

[0061] Take 25g of 4-methoxyphenyl isothiocyanate and 25g of castor oil (CAS No. 8001-79-4) as bio-based controlled release materials; add 0.25g of HKUST1(Cu) composite material to the bio-based controlled release material, stir evenly until completely dissolved, and prepare a precise controlled release membrane material with directional pore structure.

[0062] Example 3: Preparation of precise controlled release membrane with directional pore construction

[0063] 1. Preparation of MOF materials:

[0064] 3.24 g of 2-methylimidazole was added to 100 ml of methanol and stirred to prepare solution 1; 1.47 g of zinc nitrate hexahydrate was added to 100 ml of methanol to prepare solution 2; under vigorous stirring, solution 1 was quickly poured into solution 2, and a milky white uniform suspension was obtained after reaction for 30 minutes. The above suspension was centrifuged to obtain a precipitate, which was washed with methanol several times and then dried to obtain ZIF-8.

[0065] 2. Modification of MOF materials:

[0066] 0.25 g ZIF-8 was mixed with 0.25 g polydimethylsiloxane, 4 g n-heptane and 1 g ethyl silicate, and then ultrasonicated at 25° C. for 30 min and dried in vacuum to obtain a ZIF-8 composite material.

[0067] 3. Preparation of precise controlled release membrane:

[0068] Take 25g of 4-methoxyphenyl isothiocyanate and 25g of castor oil (CAS No. 8001-79-4) as bio-based controlled release materials; add 0.75g of ZIF-8 composite material to the bio-based controlled release material, stir evenly until completely dissolved, and prepare a precise controlled release membrane material with directional pore structure.

[0069] Example 4: Preparation of modified bio-based coated controlled-release fertilizer

[0070] 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of the precise controlled release film prepared in Example 1 was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, a modified bio-based controlled release fertilizer was prepared.

[0071] Example 5: Preparation of modified bio-based coated controlled-release fertilizer

[0072] 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of the precise controlled release film prepared in Example 2 was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, a modified bio-based controlled release fertilizer was prepared.

[0073] Example 6: Preparation of modified bio-based coated controlled-release fertilizer

[0074] 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of the precise controlled release film prepared in Example 3 was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, a modified bio-based controlled release fertilizer was prepared.

[0075] Comparative Example 1: Preparation of unmodified bio-based coated controlled-release fertilizer

[0076] (1) 25 g of 4-methoxyphenyl isothiocyanate and 25 g of castor oil were placed in a beaker and stirred evenly to prepare an unmodified bio-based coating solution.

[0077] (2) 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of unmodified bio-based coating liquid was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, an unmodified bio-based coated controlled-release fertilizer was prepared.

[0078] Comparative Example 2: Preparation of bio-based coated controlled-release fertilizer modified only with MOF

[0079] (1) 3.24 g of 2-methylimidazole was added to 100 ml of methanol and stirred to prepare solution 1; 1.47 g of zinc nitrate hexahydrate was added to 100 ml of methanol to prepare solution 2; under vigorous stirring, solution 1 was quickly poured into solution 2, and a milky white uniform suspension was obtained after reaction for 30 minutes. The above suspension was centrifuged to obtain a precipitate, which was washed with methanol several times and then dried to obtain ZIF-8.

[0080] (2) 25 g of 4-methoxyphenyl isothiocyanate and 25 g of castor oil were placed in a beaker, and 0.75 g of ZIF-8 was added and stirred evenly until completely dissolved to prepare a MOF-modified bio-based coating solution.

[0081] (3) 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of MOF-modified bio-based coating liquid was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, a bio-based coated controlled-release fertilizer modified only with MOF was prepared.

[0082] Comparative Example 3: Preparation of bio-based coated controlled-release fertilizer modified only with group-modified materials

[0083] (1) 0.25 g of polydimethylsiloxane, 4 g of n-heptane, and 1 g of ethyl silicate were mixed to obtain a group-modified material.

[0084] (2) Put 25 g of 4-methoxyphenyl isothiocyanate and 25 g of castor oil into a beaker, add 0.75 g of the group-modified material prepared in step (1), and stir evenly until completely dissolved to obtain a bio-based coating liquid modified with the group-modified material.

[0085] (3) 1 kg of 4-5 mm granular urea was added to a rotary coating machine and preheated to 65° C. 50 g of the bio-based coating liquid modified by the group-modified material was evenly sprayed onto the surface of the granular fertilizer at a pressure of 1 MPa. After 5-10 minutes, when the coating liquid was completely solidified, a bio-based coated controlled-release fertilizer modified only by the group-modified material was prepared.

[0086] Test example: Performance evaluation of precise controlled-release membranes with directional pore construction and bio-based coated controlled-release fertilizers prepared therefrom

[0087] 1. The MOF-303 material prepared in Example 1 was subjected to transmission electron microscopy (TEM) test and EDS element scanning analysis. The results were as follows: Figure 1 and Figure 2 The results show that the MOF-303 material prepared by the present invention has a regular square shape and a uniform and stable structure.

[0088] 2. The precise controlled release membranes prepared in Examples 1 to 3 and the unmodified bio-based coating solution of Comparative Example 1 were solidified and formed, as shown in the following photos: Figure 3 As shown. In the precise controlled release membrane prepared in Example 1, the amount of the group-modified MOF material added is 1% of the weight of the bio-based controlled release material, in the precise controlled release membrane prepared in Example 2, the amount of the group-modified MOF material added is 0.5% of the weight of the bio-based controlled release material, and in the precise controlled release membrane prepared in Example 3, the amount of the group-modified MOF material added is 1.5% of the weight of the bio-based controlled release material. The results show that as the amount of MOF added increases, the pores of the modified membrane change accordingly.

[0089] 3. Photos of the modified bio-based coated controlled-release fertilizers prepared in Examples 4 to 6 and the unmodified bio-based coated controlled-release fertilizer prepared in Comparative Example 1 are shown in FIG. Figure 4 shown.

[0090] 4. The membrane shell of the modified bio-based coated controlled-release fertilizer prepared in Example 4 was subjected to infrared spectroscopy analysis, scanning electron microscopy analysis and X-ray photoelectron spectroscopy analysis. The infrared spectroscopy analysis results of the membrane shell of the modified bio-based coated controlled-release fertilizer prepared in Example 4 are as follows: Figure 5 As shown by Figure 5 It can be seen that the coating material has characteristic absorption peaks of NH and Al. The results of SEM analysis are shown in Figure 6 As shown, the two upper images in the figure are SEM images of the unmodified bio-based coated controlled-release fertilizer membrane shell of comparative example 1 at different magnifications, and the two lower images are SEM images of the modified bio-based coated controlled-release fertilizer membrane shell of example 4 at different magnifications; it can be clearly observed that the surface of the modified controlled-release fertilizer membrane shell is relatively flat, and the pores on the surface of the membrane material are blocked by nano-scale particles (MOF composite materials), which limits the water inlet and improves the slow-release characteristics of slow-controlled fertilization. The X-ray photoelectron spectroscopy analysis results of the modified bio-based coated controlled-release fertilizer membrane shell prepared in example 4 are shown in Figure 1. Figure 7 As shown, the characteristic peaks of O1s, N1s, C1s and Al can be clearly observed, indicating that the MOF modifier and modified bio-based coated controlled-release fertilizer were successfully prepared.

[0091] 5. The nitrogen release rate of the controlled-release fertilizers prepared in Examples 4-6 and Comparative Examples 1-3 was measured according to the National Standard for Slow-Release Fertilizers GB / T 23348-2009, and the time required for the cumulative nutrient release rate to reach 80% was recorded as the controlled-release period.

[0092] The nutrient release of the controlled-release fertilizers prepared in Examples 4-6 and Comparative Example 1 within the first 30 days is as follows: Figure 8 As shown, the results show that with the increase of the addition amount of MOF modifier, the slow-release performance of the slow-release fertilizer is greatly improved.

[0093] The controlled-release period of the controlled-release fertilizer prepared in Example 6 was finally measured to be 120 days, the controlled-release period of the controlled-release fertilizer prepared in Comparative Example 1 was 80 days, the controlled-release period of the controlled-release fertilizer prepared in Comparative Example 2 was 95 days, and the controlled-release period of the controlled-release fertilizer prepared in Comparative Example 3 was 85 days. The results show that the slow-release performance of the fertilizer can be significantly improved by the joint modification of MOF and group-modified materials.

[0094] 6. The nutrient release curves of the controlled-release fertilizer prepared in Example 4 and the controlled-release fertilizer prepared in Comparative Example 1 were compared with the spinach demand curve. Fig. 9 By comparison, it was found that the unmodified bio-based slow-release fertilizer could not meet the nitrogen demand of spinach during growth, while the modified MOF-modified bio-based controlled-release fertilizer could precisely control the release and meet the growth demand of spinach.

[0095] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A precise controlled release membrane with directional pore construction, It is characterized in that Made from the following raw materials in parts by weight: 100 parts of bio-based controlled release material, 0.1-3 parts of modifier; The modifier is one or more of a ZIF-8 (Zn) composite material, a HKUST1 (Cu) composite material, and a MOF-303 (Al) composite material; The ZIF-8(Zn) composite material was prepared by the following method: After mixing ZIF-8, polydimethylsiloxane, n-heptane and ethyl silicate, ultrasonication was performed for 20-40 minutes, and drying was performed to prepare a ZIF-8 (Zn) composite material; HKUST1(Cu) composite material was prepared by the following method: HKUST-1 was fully mixed with an amino acid solution, iron oxide and ferrous sulfate, and then ultrasonicated for 2.5-3.5 hours in a nitrogen atmosphere, centrifuged to obtain a precipitate, and dried to prepare a HKUST1(Cu) composite material; The MOF-303(Al) composite material was prepared by the following method: The MOF-303 was immersed in a methanol solution containing methanesulfonic acid, stirred for 10-14 hours, and dried to obtain MeSA@MOF303; the MeSA@MOF303 was dispersed in deionized water, polyvinyl alcohol was added, and stirred at 90-100°C to obtain a uniform suspension, which was centrifuged and dried to prepare a MOF-303 (Al) composite material; The precise controlled release membrane is prepared by the following method: 4-Methoxyphenyl isothiocyanate and castor oil are used as bio-based controlled-release materials; a modifier is added to the bio-based controlled-release material, and stirred evenly until it is completely dissolved to prepare a precise controlled-release membrane material with directional pore structure.

2. Use of the precise controlled-release membrane material with directional pore construction as described in claim 1 in the preparation of controlled-release fertilizers.

3. A coated controlled-release fertilizer, It is characterized in that It comprises a fertilizer core, and the precise controlled-release membrane material with pore-oriented structure as claimed in claim 1 sprayed on the surface of the fertilizer core; the precise controlled-release membrane material with pore-oriented structure accounts for 1-5% of the weight of the fertilizer core.

4. The method for preparing the coated controlled-release fertilizer according to claim 3, It is characterized in that The following steps are involved: Preheat the fertilizer core to 50-60° C., then spray the precise controlled-release membrane material with pore-oriented structure as described in claim 1 onto the surface of the fertilizer core and cure for 5-10 minutes.

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