Organic liquid molybdenum fertilizer, preparation method and application

Abstract

The invention discloses an organic liquid molybdenum fertilizer, a preparation method and application, the preparation method comprises the following steps: mixing ammonium molybdate and a cyclic heptapeptide ligand according to a preset proportion, adding deionized water to prepare a suspension, and synchronously applying microwaves and ultrasonic waves to the suspension to obtain a nanoscale cyclic peptide-molybdenum precursor; mixing humic acid with the nano-scale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical porous structure; the preparation method comprises the following steps: dispersing TEMPO oxidized nanocellulose in a buffer solution prepared from deionized water to obtain a TEMPO oxidized nanocellulose solution, and mixing a molybdenum complex with a hierarchical porous structure with the TEMPO oxidized nanocellulose solution to obtain a molybdenum-loaded nanocapsule; monogalactose diglyceride and the molybdenum-loaded nanocapsule are mixed, and molybdenum fertilizer colloid is obtained; and performing high-pressure circulating crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, and treating the molybdenum fertilizer colloid particles to obtain the organic liquid molybdenum fertilizer with bimodal particle size distribution.

Description

Technical Field

[0001] This application belongs to the technical field of fertilizer preparation, and specifically relates to an organic liquid molybdenum fertilizer, a preparation method and an application thereof. Background Art

[0002] Molybdenum, as an essential trace element for plant growth, plays a key role in nitrogenase activity and nitrogen metabolism. However, traditional molybdenum fertilizers have significant drawbacks: molybdate ions are prone to competitive adsorption with phosphates in the soil, resulting in a substantial reduction in biological availability; the foliar penetration rate is low, making it difficult for plants to efficiently absorb; the storage stability is poor, and crystallization or stratification easily occurs in the short term. In addition, existing preparation methods mostly rely on single chelation or slow-release technologies, and it is difficult to achieve the synergistic optimization of rhizosphere-triggered release and rapid foliar absorption. The above problems seriously restrict the actual application effect of molybdenum fertilizers, and there is an urgent need to develop a molybdenum fertilizer preparation technology with high chelation stability, anti-environmental interference ability, intelligent controlled release ability and long-term storage performance. Summary of the Invention

[0003] Aiming at the deficiencies in the prior art, the main purpose of this application is to provide an organic liquid molybdenum fertilizer, a preparation method and an application thereof, aiming to improve the biological utilization rate, environmental adaptability and storage stability of molybdenum fertilizers.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] An organic liquid molybdenum fertilizer, the components of the organic liquid molybdenum fertilizer and the mass percentage of each component are: ammonium molybdate: 5.0% - 8.5%; cyclic heptapeptide ligand: 1.2% - 2.8%; humic acid: 3.5% - 6.0%; TEMPO-oxidized nanocellulose: 0.8% - 2.5%; monogalactosyldiglyceride: 0.008% - 0.015%; deionized water: the balance.

[0006] This application also provides a preparation method of an organic liquid molybdenum fertilizer, the preparation method includes: mixing ammonium molybdate and cyclic heptapeptide ligand in a preset ratio, adding deionized water to prepare a suspension, synchronously applying microwave and ultrasonic waves to the suspension to obtain a nanoscale cyclic peptide-molybdenum precursor; mixing humic acid with the nanoscale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure; dispersing TEMPO-oxidized nanocellulose in a buffer solution prepared with deionized water to obtain a TEMPO-oxidized nanocellulose solution, mixing the molybdenum complex with a hierarchical pore structure with the TEMPO-oxidized nanocellulose solution to obtain a molybdenum-loaded nanocapsule; mixing monogalactosyldiglyceride with the molybdenum-loaded nanocapsule to obtain a molybdenum fertilizer colloid; performing high-pressure cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, and processing the molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution.

[0007] Optionally, the obtaining of the cyclic peptide-molybdenum precursor includes: mixing ammonium molybdate and a cyclic heptapeptide ligand in a preset ratio to obtain a mixture; injecting deionized water into the mixture to prepare a suspension, and subjecting the suspension to microwave and ultrasonic treatments while monitoring the treatment process until the chelation degree of molybdenum and the cyclic peptide reaches a preset value, thereby obtaining a nano-level cyclic peptide-molybdenum precursor.

[0008] Optionally, the mixing of humic acid with the nano-level cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure includes: activating the humic acid to obtain plasma-activated humic acid; mixing the plasma-activated humic acid with the cyclic peptide-molybdenum precursor, and performing a cooling treatment to form a molybdenum complex with a hierarchical pore structure.

[0009] Optionally, the activation treatment of the humic acid includes: pre-treating the humic acid; performing cold plasma spraying on the pre-treated humic acid with a gradient power; and rapidly cooling the humic acid after cold plasma spraying.

[0010] Optionally, the obtaining of the molybdenum-loaded nanocapsules includes: dispersing TEMPO-oxidized nanocellulose in a buffer solution, adding N-isopropylacrylamide and acrylic acid monomers, and irradiating with ultraviolet light to obtain a TEMPO-oxidized nanocellulose solution; mixing the TEMPO-oxidized nanocellulose solution with the molybdenum complex with a hierarchical pore structure, and performing laser scanning on the mixed TEMPO-oxidized nanocellulose solution and the molybdenum complex with a hierarchical pore structure to obtain molybdenum-loaded nanocapsules.

[0011] Optionally, the mixing ratio of the TEMPO-oxidized nanocellulose solution to the molybdenum complex with a hierarchical pore structure is 1:3.

[0012] Optionally, the mixing of monogalactosyldiglyceride with the molybdenum-loaded nanocapsules to obtain a molybdenum fertilizer colloid includes: mixing monogalactosyldiglyceride with the molybdenum-loaded nanocapsules and performing liposome intercalation to obtain particles with a chloroplast membrane-like structure; monitoring the particle size change of the particles with a chloroplast membrane-like structure in real time, and when the particle size reaches the expected size, injecting a phytosterol inducer to form a chloroplast membrane-like structure; and passivating the chloroplast membrane-like structure to obtain a molybdenum fertilizer colloid.

[0013] Optionally, the high-pressure cyclic crushing treatment of the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles and the treatment of the molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution include: performing cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles; performing surface stabilization treatment on the molybdenum fertilizer colloid particles; constructing a molecular barrier and sterilizing the surface-stabilized molybdenum fertilizer colloid particles; and optimizing the rheological properties of the sterilized molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer.

[0014] The present application also provides an application of an organic liquid molybdenum fertilizer, and the organic liquid molybdenum fertilizer is applied to crops.

[0015] Compared with the prior art, the present application can bring the following beneficial effects:

[0016] Through a multi-level structure design and a collaborative processing technology, the present application realizes the efficient preparation and performance optimization of the organic liquid molybdenum fertilizer. In the present application, first, a microwave-ultrasonic wave collaborative treatment is adopted to construct a nano-level chelating precursor to ensure the stable binding of molybdenum elements; subsequently, a multi-level pore structure is formed by humic acid compounding to enhance the molybdenum loading capacity and slow-release characteristics; then, TEMPO-oxidized nanocellulose is coated to form an intelligent-responsive nano-capsule to realize environmentally regulated release; finally, through liposome intercalation and high-pressure fragmentation processes, a liquid product with a bimodal particle size distribution is obtained, which has both rapid absorption and long-term slow-release functions. The present application can significantly improve the biological utilization rate, environmental adaptability, and storage stability of the molybdenum fertilizer, and provide continuous and efficient molybdenum nutrition supply for crops. Description of the Drawings

[0017] Figure 1 is a schematic flow chart of a method for preparing an organic liquid molybdenum fertilizer provided by an embodiment of the present application. Detailed Embodiments

[0018] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0020] In the present application, unless otherwise clearly specified and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0021] In addition, if the descriptions such as "first" and "second" are involved in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0022] In an exemplary embodiment, the present application provides an organic liquid molybdenum fertilizer. The components of the molybdenum fertilizer and the mass percentages of the respective components are as follows: ammonium molybdate: 5.0% - 8.5%; cyclic heptapeptide ligand: 1.2% - 2.8%; humic acid: 3.5% - 6.0%; TEMPO (2,2,6,6 - tetramethylpiperidine - 1 - oxyl, 2,2,6,6 - Tetramethylpiperidine 1 - oxyl) - oxidized nanocellulose: 0.8% - 2.5%; monogalactosyldiglyceride: 0.008% - 0.015%; deionized water: the balance. Preferably, the components of the molybdenum fertilizer and the mass percentages of the respective components are as follows: ammonium molybdate: 7%; cyclic heptapeptide ligand: 2%; humic acid: 4.5%; TEMPO - oxidized nanocellulose: 1.8%; monogalactosyldiglyceride: 0.012%; deionized water: the balance.

[0023] The present application has conducted performance tests on the above - described organic liquid molybdenum fertilizer with the above components, and the test results are shown in Table 1:

[0024] Table 1

[0025]

[0026] As can be seen from Table 1, within the above - mentioned proportional range, all the performance indicators of the molybdenum fertilizer with the preferred ratio are optimal.

[0027] Figure 1 is a schematic flow chart of a method for preparing an organic liquid molybdenum fertilizer provided by an exemplary embodiment of the present application. As Figure 1 described, the preparation method includes the following steps:

[0028] S100: Mix ammonium molybdate and cyclic heptapeptide ligand in a preset ratio, add deionized water to prepare a suspension, and simultaneously apply microwave and ultrasonic waves to the suspension to obtain a nanoscale cyclic peptide - molybdenum precursor;

[0029] S200: Mix humic acid with the nanoscale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure;

[0030] S300: Disperse TEMPO-oxidized nanocellulose in a buffer solution prepared with deionized water to obtain a TEMPO-oxidized nanocellulose solution, and mix the molybdenum complex with a hierarchical pore structure with the TEMPO-oxidized nanocellulose solution to obtain a molybdenum-loaded nanocapsule;

[0031] S400: Mix monogalactosyldiglyceride (MGDG) with the molybdenum-loaded nanocapsule to obtain a molybdenum fertilizer colloid;

[0032] S500: Perform high-pressure cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, and process the molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution.

[0033] In another exemplary embodiment, in step S100, the obtaining of the cyclic peptide-molybdenum precursor includes the following steps:

[0034] S101: In a microwave-ultrasonic standing wave reactor, mix ammonium molybdate and a cyclic heptapeptide ligand in a set ratio to obtain a mixture, and inject deionized water into the mixture to prepare a suspension with a solid content of 3% - 5%. Apply 2.45 GHz microwave (power density 12 W / cm 3 ) and 40 kHz ultrasonic wave (sound intensity 1.2 W / cm2) to the suspension to promote conformational inversion of the peptide chain, so that molybdenum (MoO 2- ) is embedded in the cavity of the cyclic heptapeptide to form a stable chelate structure;

[0035] In this step, microwave energy can directly act on molecules to accelerate the reaction process. The cavitation effect generated by ultrasonic waves can create a local high-temperature and high-pressure environment to promote the breaking and recombination of chemical bonds. Through the synergistic effect of microwave and ultrasonic waves, conformational inversion of the peptide chain can be promoted, thereby forming a stable chelate structure. The small size (nanoscale) and lipophilicity (such as the hydrophobic part of the cyclic peptide) of this structure make it easier to penetrate the leaf cuticle, so it can easily enter the epidermal cells of plant leaves, thus improving the absorption effect of molybdenum fertilizer in plants.

[0036] S102: Use in-situ Raman spectroscopy to monitor the microwave and ultrasonic treatment process. When it is observed that the peak shift at 1078 cm-1 exceeds 5 cm -1 , it indicates that the chelation degree of molybdenum and the cyclic peptide reaches 95% or above. At this time, terminate the reaction to avoid the generation of by-products, and at this time, the nanoscale cyclic peptide-molybdenum precursor can be obtained.

[0037] In another exemplary embodiment, in step S200, the step of mixing humic acid with the nanoscale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure includes the following steps:

[0038] S201: Use an atmospheric pressure cold plasma jet to perform surface radical activation treatment on humic acid (a mixture of argon and a small amount of oxygen, with a mixing volume ratio of 95:5, and the treatment time is set at 30 s / mm according to the thickness) to obtain plasma-activated humic acid;

[0039] In this step, using an atmospheric pressure cold plasma jet to perform surface radical activation treatment on humic acid specifically includes the following steps:

[0040] Step 1: Pretreat humic acid, that is, make humic acid into a uniform thin sheet or powder to ensure the maximization of its surface area and increase the contact area between the plasma and humic acid.

[0041] Step 2: Adopt a power gradient method, that is, gradually increase the power of the atmospheric pressure cold plasma jet used to spray humic acid from a low power (such as 40 W) to the target power (80 W), and maintain the treatment time at each power level for 5 minutes. The progressive energy input method can more gently activate the surface of humic acid and reduce the risk of thermal damage.

[0042] Step 3: After the cold plasma treatment is completed, quickly cool the humic acid (for example, by rapid cooling with liquid nitrogen), which helps to fix the newly formed active sites to prevent the re-closure of the active sites due to the temperature rise.

[0043] Based on the above steps for activating humic acid, various active functional groups (such as hydroxyl groups, carboxyl groups, etc.) can be introduced on the surface of humic acid, and these functional groups can significantly improve the interaction ability between humic acid and other substances.

[0044] The humic acid (i.e., plasma-activated humic acid) after this step of treatment has better compatibility, and it is easier to induce the cooperative assembly of hydrogen bonds and π bonds under the action of a pulsed electric field, thus helping to accelerate the formation of a molybdenum complex with a hierarchical pore structure.

[0045] S202: Mix the plasma-activated humic acid with the nanoscale cyclic peptide-molybdenum precursor according to a mass ratio of 1:0.7 to 1:1.2, induce the cooperative assembly of hydrogen bonds-π bonds under the action of a pulsed electric field, and then cool down to -20 °C at a gradient and maintain for a certain time (such as 2 hours) to form a molybdenum complex with a hierarchical pore structure.

[0046] In this step, the present application adopts the following gradient cooling method for the mixed plasma-activated humic acid and nanoscale cyclic peptide-molybdenum precursor:

[0047] First, starting from room temperature, it is cooled at a rate of 1°C per minute to 4°C and maintained for 30 minutes to stabilize the initially formed structure.

[0048] Next, the cooling rate is adjusted to 0.5°C per minute and cooled to -5°C, and maintained at this temperature for 1 hour to further promote intermolecular interactions and refinement of the structure.

[0049] Finally, it is continued to be slowly cooled to the target temperature of -20°C at a rate of 0.1°C per minute and maintained at this temperature for at least 2 hours to ensure that the formed hierarchical pore structure is stable enough.

[0050] In this embodiment, by adopting gradient cooling, the thermal motion between molecules or particles can be gradually reduced, which helps to prevent irregular aggregation or crystallization caused by rapid cooling. At a lower thermal motion state, it is easier for molecules to form oriented arrangements and ordered packings. In addition, under the action of a pulsed electric field, preliminary weak interactions of hydrogen bonds and π bonds have begun between plasma-activated humic acid and the cyclopeptide-molybdenum precursor. During the subsequent gradient cooling process, as the temperature decreases, these weak interaction forces will tend to be stable, which is beneficial to the formation of a more compact and ordered composite structure. Especially at low temperatures, the intermolecular interactions become stronger and more persistent, which helps to construct a complex hierarchical pore structure.

[0051] In another exemplary embodiment, in step S300, the obtaining of the molybdenum-loaded nanocapsules includes the following steps:

[0052] S301: Disperse TEMPO-oxidized nanocellulose in a buffer solution (such as phosphate buffer solution, Tris-HCl buffer solution, and boric acid-borax buffer solution) prepared with deionized water, add N-isopropylacrylamide and acrylic acid monomers, and initiate graft copolymerization under ultraviolet light irradiation so that N-isopropylacrylamide and acrylic acid monomers are grafted onto the nanocellulose to obtain a TEMPO-oxidized nanocellulose solution;

[0053] S302: Use a microfluidic chip (channel width 200 μm) to mix the TEMPO-oxidized nanocellulose solution with the molybdenum complex with a hierarchical pore structure at a volume ratio of 1:3, and prepare monodisperse core-shell structure droplets (0 < PDI < 0.1, polydispersity index) by the droplet template method. Finally, perform photocrosslinking curing on the monodisperse core-shell structure droplets by 405 nm laser scanning to form molybdenum-loaded nanocapsules, where the core of the capsule is the molybdenum complex with a hierarchical pore structure and the shell layer is the TEMPO-oxidized nanocellulose network.

[0054] In this step, it has been verified that the reason for mixing the TEMPO-oxidized nanocellulose solution with the molybdenum complex with a hierarchical pore structure in a volume ratio of 1:3 is that, at this ratio, the core and shell thickness of the nanocapsules can be better controlled, which helps to improve the efficiency of graft copolymerization and subsequent photocrosslinking curing. If the ratio is greater than this value, it will lead to an excessive amount of shell material, making it difficult to form a core-shell structure with an ideal size, and even incomplete encapsulation may occur, affecting the stability and functionality of the nanocapsules. Conversely, if the ratio is less than this value, it will result in a relatively excessive core part, and the shell will not be sufficient to completely cover the core, which is also not conducive to forming a stable core-shell structure and may affect the release behavior and other key performance indicators of the final product.

[0055] It should be noted that in the molybdenum-loaded nanocapsules, the shell formed by TEMPO-oxidized nanocellulose can isolate the external environment (such as phosphates and acidic substances in the soil), preventing the molybdate (MoO4 2- ) from undergoing competitive adsorption or precipitation reactions with other ions, thereby protecting the chemical stability of molybdenum. In addition, the core-shell structure (with the core being the molybdenum complex and the shell being the nanocellulose network) can prevent the leakage of molybdenum components during subsequent high-pressure crushing or storage through mechanical strength. Further, the molybdenum-loaded nanocapsules can also achieve intelligent controlled release, that is, in the slightly acidic rhizosphere environment of plants (pH 5.5 - 6.5), the carboxyl groups of the shell (from TEMPO-oxidized nanocellulose) can be protonated, expanding the pores, thereby triggering the targeted release of molybdenum. The released molybdenum complex can penetrate the micropores of the leaf cuticle and directly enter the epidermal cells.

[0056] In another exemplary embodiment, in step S400, the mixing of monogalactosyldiacylglycerol with the molybdenum-loaded nanocapsules to obtain the molybdenum fertilizer colloid includes the following steps:

[0057] S401: Mix monogalactosyldiacylglycerol (MGDG) with the molybdenum-loaded nanocapsules in a mass ratio of 1:200, and perform liposome intercalation under supercritical CO2 conditions (pressure 10 MPa, temperature 35 °C) to obtain particles with a chloroplast membrane-like structure;

[0058] In this step, the liposome intercalation of the mixed monogalactosyldiacylglycerol (MGDG) and the molybdenum-loaded nanocapsules under supercritical CO2 conditions specifically includes the following steps:

[0059] Step 1: Weigh monogalactosyldiacylglycerol (MGDG) and the molybdenum-loaded nanocapsules in a mass ratio of 1:200, and uniformly mix the two;

[0060] Step 2: Place the mixed monogalactosyldiacylglycerol (MGDG) and molybdenum-loaded nanocapsules in an autoclave, which ensures uniform distribution of the mixture and prevents it from moving due to pressure changes;

[0061] Step 3: Conduct supercritical CO2 treatment so that CO2 flows through the autoclave containing monogalactosyldiacylglycerol (MGDG) and molybdenum-loaded nanocapsules. During this process, supercritical CO2 can promote the entry of MGDG molecules into and their embedding into the lipid bilayer structure formed on the surface of the molybdenum-loaded nanocapsules.

[0062] Step 4: After the liposome intercalation is completed, slowly release the pressure in the autoclave to restore the system to atmospheric pressure. During the pressure release process, it is necessary to control the decompression rate to avoid unnecessary physical damage to the sample. Collect the treated sample to obtain particles with a chloroplast membrane-like structure.

[0063] S402: Real-time monitor the particle size change of the particles with a chloroplast membrane-like structure by dynamic light scattering. When the particle size reaches the expected size (for example, the particle size reaches 80 ± 5 nm), inject a phytosterol inducer (β-sitosterol, 0.002% - 0.005%) to form a chloroplast membrane-like structure;

[0064] In this step, when the phytosterol inducer is injected into the particles with a chloroplast membrane-like structure, the following key effects will occur:

[0065] Insertion into the lipid bilayer: The hydrophobic sterol ring of β-sitosterol embeds into the lipid membrane formed by MGDG, with the hydrophilic hydroxyl group facing outwards and being arranged in an oriented manner with the lipid molecules.

[0066] Inducing membrane reorganization: The rigid structure of the sterol promotes the close packing of lipid molecules to form an ordered bilayer structure similar to the natural chloroplast membrane (similar to the thylakoid membrane).

[0067] Regulating the particle size: The sterol can fill the gaps between lipid molecules, reduce membrane fluidity, and can mimic the characteristics of chloroplast membrane microdomains.

[0068] S403: Passivate the chloroplast membrane-like structure using tangential flow filtration (100 kDa membrane package) to obtain a molybdenum fertilizer colloid.

[0069] In this step, passivating the chloroplast membrane-like structure specifically includes the following steps:

[0070] Step 1: Uniformly disperse the chloroplast membrane-like structure in an appropriate buffer solution (such as phosphate buffer, boric acid-borax buffer) to obtain a dispersion, avoiding particle aggregation to maintain colloid stability;

[0071] Step 2: Before entering the TFF (Tangential Flow Filtration System), the dispersion is pre-treated through a coarse filter (such as a 5μm pore size) to remove large particle impurities, which helps extend the service life of the 100kDa membrane package and improve efficiency;

[0072] Step 3: First, filter the dispersion after removing large particles at a relatively low pressure (such as 0.5 bar), and gradually increase it to the target pressure (such as 2 bar). Through gradient pressure boosting filtration, it helps reduce the risk of particle clogging of the membrane pores.

[0073] Step 4: Adopt a multi-cycle filtration mode, monitor the purity of the dispersion in real time, check the impurity content in the dispersion after each cycle until the required purity standard is reached. After each cycle, adjust the flow rate and pressure to ensure the best filtration effect. At the same time, during the filtration process, gradually add an appropriate amount of non-ionic surfactant (such as Tween 80 or polyvinyl alcohol PVA) to form a protective film on the surface of the chloroplast-mimicking membrane structure particles to prevent aggregation between particles without affecting their subsequent application performance.

[0074] Step 5: After the cycle filtration is completed, use an ultrasonic processor to perform ultrasonic treatment (such as 1 minute) on the collected molybdenum fertilizer colloid to help further disperse any possible small aggregates formed.

[0075] The passivation treatment steps shown above can not only effectively purify the chloroplast-mimicking membrane structure, but also enhance the stability and functional performance of the molybdenum fertilizer colloid through surface modification adjustment.

[0076] In another exemplary embodiment, in step S500, the molybdenum fertilizer colloid is subjected to high-pressure cyclic crushing treatment to obtain molybdenum fertilizer colloid particles, and the molybdenum fertilizer colloid particles are processed to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution, including the following steps:

[0077] S501: Perform gradient pressure segmented crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, specifically including:

[0078] The first stage (coarse crushing): Perform cyclic crushing treatment 3 times at a pressure of 150 MPa, and break large particles (>500nm) into medium particles with a particle size of about 200nm through strong shear force, forming the prototype of the secondary peak.

[0079] The second stage (fine homogenization): Increase the pressure to 250 MPa and further perform cyclic crushing treatment on the medium particles 5 times. Utilize the cavitation effect and high-speed impact to further refine the particles to a main peak of 50nm and a secondary peak of 120nm.

[0080] The third stage (dynamic balance): Perform cyclic crushing treatment twice under a pressure of 200 MPa to balance the tendency of particle collision and agglomeration, and ensure the formation of a bimodal particle size distribution (a main peak of 50 ± 5 nm and a secondary peak of 120 ± 10 nm).

[0081] Through gradient pressure segmented treatment, the process of molybdenum fertilizer colloid particle crushing and recombination can be accurately regulated, avoiding the single particle size distribution caused by a single high pressure.

[0082] It should be noted that during the above crushing treatment process, the temperature of the molybdenum fertilizer colloid needs to be maintained between 10 °C and 15 °C through an internal cooling system to inhibit particle thermal motion. And, liquid nitrogen (-196 °C) needs to be injected instantaneously for rapid cooling for 1 second during the high-pressure cycle interval to induce microcracks on the particle surface and enhance the subsequent crushing efficiency.

[0083] It also should be noted that after each gradient pressure segmented treatment, the pressure is released in a pulse mode (the pressure drops to atmospheric pressure within 0.1 second), which helps to promote uniform dispersion of particles, avoid local agglomeration, and thus enhance the uniformity of the bimodal distribution.

[0084] In summary, high-pressure cyclic crushing treatment can refine molybdenum fertilizer colloid particles, and the particle size distribution can be accurately controlled through bimodal regulation. Among them, the main peak is used for rapid foliar absorption, and the secondary peak is used for rhizosphere slow release. The use of double surfactants (Pluronic F127 + nano-silica) and buffer solution helps to maintain the dispersed state. In addition, low-temperature treatment can further optimize the particle distribution and ensure the stability of the liquid state.

[0085] S502: Add amphiphilic block copolymer (such as Pluronic F127, concentration 0.1% - 0.3%) and nano-silica (particle size 5 nm, concentration 0.05% - 0.1%) to the molybdenum fertilizer colloid particles, inhibit the aggregation of large particles through hydrophobic interaction and stabilize small particles through steric hindrance effect respectively, and form a "double barrier" to prevent the merger of the two peaks. In addition, a buffer solution prepared with deionized water (such as phosphate buffer solution, PH 7.0) needs to be injected synchronously to maintain the surface charge balance of the molybdenum fertilizer colloid particles (Zeta potential > ±30 mV), strengthen the electrostatic repulsion effect, and maintain the long-term dispersed stability of the molybdenum fertilizer colloid particles.

[0086] In this step, the main peak (small particles) and the secondary peak (large particles) are locked respectively through a differential surface modification strategy to prevent the merger of the two peaks. After the above treatment, surface-modified stabilized molybdenum fertilizer colloid particles are obtained.

[0087] S503: Add perfluoropolyether as a stabilizer to the obtained surface-modified stabilized molybdenum fertilizer colloid particles, and perform pulsed intense light and low-temperature plasma sterilization.

[0088] In this step, pulsed intense light can kill the microorganisms on the surface of colloidal particles, while low-temperature plasma can completely sterilize (total colony count < 10 CFU / mL). Due to its low surface energy and high chemical inertness, perfluoropolyether can be evenly adsorbed on the surface of molybdenum fertilizer colloidal particles, thus forming a continuous molecular barrier. This barrier can physically isolate the direct contact between molybdenum fertilizer colloidal particles, reduce the aggregation caused by van der Waals forces, and thus inhibit the precipitation and stratification of molybdenum fertilizer colloidal particles. At the same time, this barrier layer can block oxygen and moisture, slow down the oxidation reaction or hydrolysis reaction, and thus enhance the storage stability of molybdenum fertilizer.

[0089] S504: Optimize the rheological properties of the sterilized molybdenum fertilizer colloidal particles to obtain organic liquid molybdenum fertilizer. Optimizing the rheological properties of the sterilized molybdenum fertilizer colloidal particles includes the following steps:

[0090] Step 1: Slowly add xanthan gum (natural polysaccharide, concentration 0.05% - 0.2%) to the sterilized molybdenum fertilizer colloidal particles, and at the same time stir at a speed of 500 rpm for 30 minutes until the xanthan gum and the sterilized molybdenum fertilizer colloidal particles are completely dissolved to form a homogeneous colloid.

[0091] In this step, xanthan gum combines with water molecules through hydrogen bonds to form a three-dimensional network structure, which can increase the viscosity of the system (the dynamic viscosity can be adjusted to 50 - 200 mPa·s) to prevent the molybdenum fertilizer colloidal particles from settling.

[0092] Step 2: Place the homogeneous colloid in an ultrasonic processor (frequency 40 kHz, power 200 W) and process it for 10 - 15 minutes. During the process, keep the temperature at 20 - 25°C. After processing, a homogenized colloid is obtained.

[0093] In this step, the ultrasonic cavitation effect can break up small aggregates, ensure the uniformity of the bimodal distribution (main peak 50 ± 5 nm, secondary peak 120 ± 10 nm), and at the same time improve the fluidity, making the liquid molybdenum fertilizer easier to pump or spray.

[0094] Step 3: Place the homogenized colloid in a programmable temperature incubator and perform staged treatment. After the treatment, a stabilized colloid is obtained;

[0095] In this step, the staged treatment specifically includes the following three stages:

[0096] The first stage: Let it stand at 25°C for 12 hours to promote the adsorption of stabilizers on the particle surface.

[0097] The second stage: Refrigerate at 4°C for 6 hours to induce the formation of a polysaccharide network structure.

[0098] The third stage: Return to room temperature (25°C) and detect the rheological properties.

[0099] Through the gradient temperature change, the directional binding of polysaccharides and colloidal particles can be promoted, thus facilitating the formation of a stable gel network.

[0100] Step 4: Add carboxymethyl chitosan (concentration 0.05% - 0.1%) to the stabilized colloid, and stir for 1 hour to obtain the organic liquid molybdenum fertilizer.

[0101] In this step, carboxymethyl chitosan can act synergistically with xanthan gum to ensure that chitosan coats the surface of molybdenum fertilizer colloidal particles through electrostatic interaction. Chitosan has a natural antibacterial effect, which can reduce the risk of secondary pollution after sterilization.

[0102] Next, the present application compares the molybdenum fertilizer prepared based on the above method with the molybdenum fertilizer prepared based on the traditional method, as shown in Table 2 specifically:

[0103] Table 2

[0104]

[0105] As can be seen from Table 2, compared with the molybdenum fertilizer prepared by the traditional method, the molybdenum fertilizer prepared by the method described in the present application has been greatly improved in terms of molybdenum chelation rate, phosphate interference resistance, leaf surface penetration rate, rhizosphere trigger release rate, and storage stability.

[0106] Furthermore, the present application also shows the comparison of the effects of the molybdenum fertilizer prepared by this method and the molybdenum fertilizer prepared by the traditional method in specific applications.

[0107] The applicant planted soybeans in molybdenum-deficient acidic soil (pH 5.5), and applied the molybdenum fertilizers prepared by the method described in the present application (Group A) and the traditional method (Group B) respectively, with a dosage of 50 g / mu. The growth of soybeans from the seedling stage to the harvest stage was monitored throughout the process, and the growth data of soybeans at different stages were recorded in real time, as follows:

[0108] 1. Seedling stage:

[0109] Seedling stage (after 15 days)

[0110] Group A:

[0111] The leaves are dark green and there is no chlorosis phenomenon.

[0112] The average root length increases by 30%, and the number of root nodules is large and plump (molybdenum is a key component of nitrogenase).

[0113] Group B:

[0114] The leaves are slightly chlorotic (molybdenum is fixed by the soil).

[0115] The root development is retarded, and the number of root nodules is small and small.

[0116] 2. Flowering stage:

[0117] Group A:

[0118] There is a large amount of flowering and high pollen viability (molybdenum promotes reproductive growth).

[0119] Leaf surface detection shows that the molybdenum content reaches 12 ppm (efficient absorption).

[0120] Group B:

[0121] Flowering is delayed and some flower buds fall off.

[0122] The molybdenum content on the leaf surface is only 3 ppm (insufficient absorption).

[0123] 3. Harvest period:

[0124] Group A:

[0125] The number of pods per plant increases by 25%, the grains are plump, and the protein content increases by 18%.

[0126] The yield per mu reaches 320 kg, with a 40% increase in production compared to Group B.

[0127] Group B:

[0128] The pods are sparse, there are many shriveled grains, and the yield per mu is only 230 kg.

[0129] Based on the growth data recorded above, the following conclusions can be drawn:

[0130] The molybdenum fertilizer prepared by the method described in this application can significantly improve the yield and quality of crops through intelligent controlled release and efficient absorption in practical applications, while traditional molybdenum fertilizers have low efficiency due to easy failure and poor absorption.

[0131] In addition, this application also applies the molybdenum fertilizer prepared by this method to common crops such as wheat and corn, and compares it with traditional molybdenum fertilizers, as shown in Table 3 specifically:

[0132] Table 3

[0133]

[0134]

[0135] As can be seen from Table 3, in addition to soybeans, the organic liquid molybdenum fertilizer prepared in this application is also applicable to crops with high molybdenum element requirements such as wheat and corn, and compared with traditional molybdenum fertilizers, the molybdenum fertilizer prepared in this application can greatly improve various performance indicators of corn and wheat.

[0136] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present application.

Claims

1. An organic liquid molybdenum fertilizer, characterized in that, The components of the organic liquid molybdenum fertilizer and the mass percentage of each component are as follows: Ammonium molybdate: 5.0% - 8.5%; Cyclic heptapeptide ligand: 1.2% - 2.8%; Humic acid: 3.5% - 6.0%; TEMPO-oxidized nanocellulose: 0.8% - 2.5%; Monogalactosyldiglyceride: 0.008% - 0.015%; Deionized water: the balance.

2. A preparation method of an organic liquid molybdenum fertilizer, characterized in that, The preparation method includes: Mix ammonium molybdate and cyclic heptapeptide ligand in a preset ratio, add deionized water to prepare a suspension, and simultaneously apply microwave and ultrasonic waves to the suspension to obtain a nanoscale cyclic peptide-molybdenum precursor; Mix humic acid with the nanoscale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure; Disperse TEMPO-oxidized nanocellulose in a buffer solution prepared with deionized water to obtain a TEMPO-oxidized nanocellulose solution, and mix the molybdenum complex with a hierarchical pore structure with the TEMPO-oxidized nanocellulose solution to obtain a molybdenum-loaded nanocapsule; Mix monogalactosyldiglyceride with the molybdenum-loaded nanocapsule to obtain a molybdenum fertilizer colloid; Perform high-pressure cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, and process the molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution.

3. The preparation method of the organic liquid molybdenum fertilizer according to claim 2, characterized in that, The obtaining of the cyclic peptide-molybdenum precursor includes: Mix ammonium molybdate and cyclic heptapeptide ligand in a preset ratio to obtain a mixture; Inject deionized water into the mixture to prepare a suspension, perform microwave and ultrasonic treatment on the suspension, and simultaneously monitor the treatment process until the chelation degree of molybdenum and cyclic peptide reaches a preset value to obtain a nanoscale cyclic peptide-molybdenum precursor.

4. The preparation method of the organic liquid molybdenum fertilizer according to claim 2, characterized in that The mixing of humic acid with the nanoscale cyclic peptide-molybdenum precursor to obtain a molybdenum complex with a hierarchical pore structure includes: Perform activation treatment on humic acid to obtain plasma-activated humic acid; Mix the plasma-activated humic acid with the cyclic peptide-molybdenum precursor, and form a molybdenum complex with a hierarchical pore structure after cooling treatment.

5. The preparation method of the organic liquid molybdenum fertilizer according to claim 4, characterized in that, The activation treatment of humic acid includes: Perform pretreatment on humic acid; Perform cold plasma spraying on the pretreated humic acid with a gradient power; Perform rapid cooling on the humic acid after cold plasma spraying.

6. The preparation method of the organic liquid molybdenum fertilizer according to claim 2, characterized in that The obtaining of the molybdenum-loaded nanocapsule includes: Disperse TEMPO-oxidized nanocellulose in a buffer solution, add N-isopropylacrylamide and acrylic acid monomers, and irradiate under ultraviolet light to obtain a TEMPO-oxidized nanocellulose solution; Mix the TEMPO-oxidized nanocellulose solution with the molybdenum complex with a hierarchical pore structure, and perform laser scanning on the mixed TEMPO-oxidized nanocellulose solution and the molybdenum complex with a hierarchical pore structure to obtain a molybdenum-loaded nanocapsule.

7. The preparation method of the organic liquid molybdenum fertilizer according to claim 6, characterized in that, The mixing ratio of the TEMPO-oxidized nanocellulose solution to the molybdenum complex with a hierarchical pore structure is 1:

3.

8. The preparation method of the organic liquid molybdenum fertilizer according to claim 2, wherein, The mixing of monogalactosyldiglyceride with the molybdenum-loaded nanocapsule to obtain a molybdenum fertilizer colloid includes: Mix monogalactosyldiglyceride with the molybdenum-loaded nanocapsule and perform liposome intercalation to obtain particles with a chloroplast membrane-like structure; Monitor the particle size change of the particles with the chloroplast membrane structure mimic in real time. When the particle size reaches the expected size, inject a phytosterol inducer to form a chloroplast membrane structure mimic; Passivate the chloroplast membrane structure mimic to obtain a molybdenum fertilizer colloid.

9. The preparation method of the organic liquid molybdenum fertilizer according to claim 2, characterized in that, Perform a high-pressure cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles, and process the molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer with a bimodal particle size distribution, including: Perform a cyclic crushing treatment on the molybdenum fertilizer colloid to obtain molybdenum fertilizer colloid particles; Perform a surface stabilization treatment on the molybdenum fertilizer colloid particles; Construct a molecular barrier and sterilize the surface-stabilized molybdenum fertilizer colloid particles; Optimize the rheological properties of the sterilized molybdenum fertilizer colloid particles to obtain an organic liquid molybdenum fertilizer.

10. Application of an organic liquid molybdenum fertilizer, characterized in that, Apply the organic liquid molybdenum fertilizer to crops.

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