Preparation method of amino acid liquid fertilizer

Abstract

The invention relates to the technical field of agricultural chemistry and fertilizers, and particularly discloses a preparation method of an amino acid liquid fertilizer. The composition comprises the following raw materials: compound amino acid, soluble salts of boron and zinc, potassium salts, humic acid, an inorganic mineral material, a natural polysaccharide stabilizer and a slow-release carrier material. The preparation method comprises the following steps: pretreating raw materials, sequentially constructing a physical barrier and a steric hindrance stabilizing layer, introducing an environmental response carrier to form a functionalized composite liquid, reacting the raw materials with the functionalized composite liquid to form an amino acid chelating liquid, and filtering, concentrating at low temperature and cooling to obtain a finished product. The composition can be used for foliage spraying and root drip irrigation of crop planting, and has the advantages of high storage stability and good matching of nutrient release and crop requirements; in addition, the preparation method disclosed by the invention has the advantages of synergistic and ordered process, high controllability and no need of additionally adding a chemically synthesized chelating agent and a stabilizer.

Description

TECHNICAL FIELD

[0001] The application relates to the field of agricultural chemistry and fertilizer technology, in particular to a preparation method of an amino acid liquid fertilizer. BACKGROUND

[0002] As a kind of high-efficiency water-soluble fertilizer, the amino acid liquid fertilizer is widely used in agricultural production due to its characteristics of easy absorption by crops and convenient application. Its core role is to provide key nutrients such as amino acids and trace elements for crop growth, promote crop growth and development, and improve the yield and quality of agricultural products. At the same time, it meets the development needs of modern ecological agriculture for high efficiency and functionalization of fertilizers. With the progress of agricultural planting technology, crops have higher requirements for the stability and controllability of nutrient supply of fertilizers. High-quality amino acid liquid fertilizer needs to maintain system stability during long-term storage, avoid stratification and nutrient degradation, and realize the orderly release of nutrients according to the growth cycle of crops to ensure the precise matching of nutrient supply and crop demand.

[0003] The preparation method of traditional amino acid liquid fertilizer mostly adopts a simple raw material mixing and compounding process, lacks the design of synergistic regulation of system stability and nutrient release characteristics, and some products rely on the addition of chemically synthesized chelating agents and stabilizers to maintain system stability. This leads to the common problem of insufficient system stability in traditional products, which is prone to stratification and precipitation during long-term storage. At the same time, the release rate of nutrients is difficult to control, which is prone to problems such as nutrient loss due to excessive release in the early stage and insufficient supply in the later stage. Therefore, it cannot balance the system stability and controllability of nutrient release, which limits the application effect of amino acid liquid fertilizer in agricultural production. SUMMARY

[0004] In order to solve the problem that the amino acid liquid fertilizer in the prior art cannot balance the system stability and controllability of nutrient release, the application provides a preparation method of an amino acid liquid fertilizer.

[0005] A preparation method of an amino acid liquid fertilizer, comprising the following steps: S1, raw material pretreatment: providing raw materials containing complex amino acids, trace elements, potassium salt and synergist; S2, constructing a physical barrier: adding inorganic mineral material to a dispersion medium, and performing first dispersion treatment under high-speed shearing conditions to obtain a material pre-dispersion liquid; S3, constructing a steric hindrance stabilization layer: adding a natural polysaccharide stabilizer to the material pre-dispersion liquid, and performing second dispersion treatment to form a complex stabilizer solution; S4, introducing an environment-responsive carrier: providing a slow-release carrier material, mixing it with the complex stabilizer solution to form a functionalized composite liquid; S5, reaction synthesis and integration: the pretreated raw material in step S1 and the functionalized complex solution obtained in step S4 are jointly put into a reaction kettle for reaction to form an amino acid chelate solution; S6, post-treatment and finished product: the reaction completed amino acid chelate solution is sequentially filtered, low temperature concentrated and cooled to obtain a finished product of amino acid liquid fertilizer.

[0006] By adopting the above technical scheme, the specific inorganic mineral material is dispersed by high-speed shearing to form a physical barrier, which reduces the direct contact of nutrients with the outside environment by blocking the erosion of the outside environment to the inside nutrients; the natural polysaccharide stabilizer is added to the pre-dispersed liquid and dispersed to form a steric hindrance stabilization layer, which prevents the aggregation of particles in the system by intermolecular interaction, and forms a synergistic stabilization effect with the physical barrier, the physical barrier blocks the erosion of the macro environment, and the steric hindrance stabilization layer inhibits the aggregation of micro particles, both of which build a double protection to reduce nutrient degradation and system stratification. After the introduction of the slow-release carrier material and the composite stabilizer solution are fused, the nutrient release channel is regulated by the structure characteristics of the slow-release carrier material, and the precise intervention of nutrient release is realized; and the slow-release carrier can be uniformly carried by the double stabilization system, avoiding the uneven release of nutrients caused by the aggregation of the carrier. The pretreated raw material and the functionalized complex solution form a stable amino acid chelate solution in the reaction kettle through chemical bonding and physical action, and the finished product is obtained after removing impurities and regulating the state. The whole process only relies on natural polysaccharide stabilizer and slow-release carrier material to realize chelation and stabilization function, and the technical means of each link cooperates to make each component form a structure stable, nutrient release controllable organic whole, which guarantees the performance stability from the whole chain of preparation process to product application.

[0007] Preferably, in step S1, the complex amino acid is derived from the enzymatic hydrolysate or fermentation broth of plant protein, and the free amino acid content is 100-200 g / L; the synergist includes humic acid, and the final concentration in the reaction system is 20-50 g / L; the trace elements include boron and zinc, which are added in the form of soluble salt.

[0008] By adopting the technical scheme, in the raw material pretreatment link of step S1, the enzyme solution or fermentation liquor of plant protein is selected as the source of the complex amino acid, the complex amino acid of the source is rich in various natural amino acid components, has stronger adaptability to the nutrients required for crop growth, and can provide high-quality nutrient basis for the product. The synergist is selected from humic acid, which can adjust the colloidal properties by reducing the surface tension of the material system and increasing the wettability of the nutrient components, and at the same time, the material interface properties are improved by forming hydrogen bond interaction with other components, thereby promoting the dissolution and dispersion of other nutrient components, and providing a suitable medium environment for the subsequent chelation reaction. The trace elements include boron and zinc, and are added in the form of soluble salt, which can ensure that the boron and zinc elements are quickly dissolved in the system, and facilitate the full contact with the complex amino acid and other raw materials. The potassium salt as one of the raw materials not only provides essential potassium nutrients for crop growth, but also adjusts the ionic strength of the system, assists in stabilizing the dispersion state of the material, and cooperates with other components to lay the foundation for the subsequent formation of stable chelate structure and the improvement of nutrient synergistic effect.

[0009] Preferably, in step S2, the inorganic mineral material is at least one of silicon dioxide, montmorillonite or hydrotalcite, and the particle size D 90 The distribution range is 50-150nm, and the addition amount is 0.1-1.5% of the mass of the complex amino acid; the linear velocity of the high-speed shearing is 15-30m / s, and the treatment time is 40-60min.

[0010] By adopting the technical scheme, in the physical barrier construction link of step S2, silicon dioxide, montmorillonite or hydrotalcite is selected as the inorganic mineral material, which has good dispersibility and structural stability, and the surface is rich in active sites such as hydroxyl groups, which can provide anchoring sites for the adsorption of the subsequent natural polysaccharide stabilizer. The first dispersion treatment is carried out by high-speed shearing, which breaks the material agglomerates by shearing force, so that the inorganic mineral material is uniformly dispersed in the dispersion medium, and a dense physical isolation layer is formed by the particle accumulation. The isolation layer can block the erosion of external oxygen, moisture and other factors on the internal nutrients, reduce the oxidation degradation and loss of nutrients; at the same time, the uniformly dispersed inorganic mineral particles provide a uniform support base for the construction of the subsequent steric hindrance stabilizing layer, ensuring that the molecular network formed by the subsequent natural polysaccharide stabilizer can be fully covered, thereby providing a basic guarantee for the system stability.

[0011] Preferably, in step S3, the temperature of the second dispersion treatment is 40-60℃; the natural polysaccharide stabilizer is at least one of a chitosan derivative, sodium alginate or xanthan gum, and the addition amount is 0.5-2.0% of the mass of the complex amino acid.

[0012] By adopting the technical scheme, in the step S3 of constructing the steric hindrance stabilizing layer, chitosan derivatives, sodium alginate or xanthan gum are selected as the natural polysaccharide stabilizer, the molecular structure of the material contains a large number of hydrophilic groups and active sites, which can form hydrogen bond adsorption and combination with the hydroxyl groups on the surface of the inorganic mineral material, and can form an interlaced molecular network in the system. The second dispersion treatment can promote the dissolution and molecular stretching of the natural polysaccharide stabilizer, enhance the dispersion uniformity of the natural polysaccharide stabilizer in the material pre-dispersion liquid, and prevent the re-aggregation of the inorganic mineral particles through the steric hindrance effect. At the same time, the molecular network can wrap part of the nutrients, reduce the direct contact of the nutrients with the external environment, and further reduce the risk of nutrient loss. The stabilizing layer and the physical barrier cooperatively construct a double stabilizing system, which not only strengthens the structural stability of the entire material system, but also provides a mild dispersion environment for the uniform dispersion of the subsequent slow-release carrier material, avoiding the aggregation of the carrier material.

[0013] Preferably, in the step S4, the slow-release carrier material is at least one of a pH-sensitive microcapsule or an enzymatic polymer microsphere; the stirring speed of the mixing treatment is 50-150 r / min, and the mixing time is 30-90 min.

[0014] By adopting the technical scheme, in the step S4 of introducing the environment-responsive carrier, a pH-sensitive microcapsule or an enzymatic polymer microsphere is selected as the slow-release carrier material, which has environment-responsive characteristics and can adjust its structure state according to the change of the external environment. The mixing treatment can ensure that the slow-release carrier material is fully contacted and fused with the composite stabilizer solution, avoiding the destruction of the structural integrity of the carrier material caused by high rotation speed. The slow-release carrier material is uniformly dispersed in the system by forming hydrogen bonds and other interactions with the natural polysaccharide molecules in the composite stabilizer solution, and the molecular network formed by the natural polysaccharide can provide spatial support for the slow-release carrier to prevent its sedimentation or aggregation. The pH-sensitive carrier can control the nutrient release by changing the permeability of the capsule wall, and the enzymatic carrier can achieve gradual release of nutrients by breaking chemical bonds, and its environment-responsive characteristics can accurately adjust the release rate and rhythm of nutrients according to the pH change or enzymatic environment around the crop roots in the subsequent application process, providing a structural basis for the orderly release of nutrients; at the same time, the physical barrier and the steric hindrance stabilizing layer cooperatively act to ensure the structural stability of the carrier itself and ensure that the nutrient release matches the crop demand, further optimizing the comprehensive performance of the system.

[0015] Preferably, the capsule wall material of the pH-sensitive microcapsule is an acrylic resin copolymer or a cellulose derivative.

[0016] By adopting the technical scheme, the capsule wall material of the pH-sensitive microcapsule is selected from acrylic resin copolymer or cellulose derivative, both of which have pH response characteristics, and the functional groups such as carboxyl and amino contained in the molecular structure thereof can be dissociated or conformational transition with the change of the environmental pH value: when the environmental pH value is in a specific range of crop root system, the dissociation degree of the functional groups is increased, the swelling rate of the capsule wall material is increased, and more pore diameter channels are formed; when it is in a non-target pH environment, the dissociation degree of the functional groups is low, and the capsule wall remains in a dense state, thereby regulating the permeability of the capsule wall. Both the acrylic resin copolymer and the cellulose derivative have good biocompatibility and structural stability, and are not prone to degradation during preparation and storage, so as to ensure the structural integrity of the microcapsule. Meanwhile, both the materials can form a uniform and dense capsule wall structure through a conventional preparation process, and can encapsulate nutrients inside, maintain low permeability to reduce nutrient leakage in a non-target pH environment, and increase the permeability to realize nutrient release in a specific pH environment of crop root system, so as to accurately match the nutrient demand rhythm of crops.

[0017] Preferably, the material of the enzymatic polymer microsphere is a polyester macromolecule, and the main chain of the polyester macromolecule contains chemical bonds that can be specifically cut by phosphatase or urease secreted by plant roots.

[0018] By adopting the technical scheme, the enzymatic polymer microsphere is selected from a polyester macromolecule as the material, the polyester macromolecule has good biodegradability and structural controllability, and can be processed to form a porous or core-shell structure, so as to facilitate the encapsulation of nutrients and provide channels for nutrient release. The main chain of the polyester macromolecule contains chemical bonds that can be specifically cut by phosphatase or urease secreted by plant roots, and the chemical bonds have high enzyme recognition specificity and are only broken when contacting the secretions of corresponding plant roots. When the microsphere is applied to soil, the main chain structure remains stable in the non-crop root system area, and the porous / core-shell structure can effectively encapsulate nutrients to avoid loss; when contacting phosphatase or urease secreted by plant roots, the specific chemical bonds are broken, the microsphere is gradually degraded in layers from the surface to the inside, the pore size is gradually increased or the shell layer is shed, and then the internal nutrients are slowly released, so as to realize the accurate matching of nutrient release and crop root system growth demand. Meanwhile, the degradation products of the polyester macromolecule are small molecule esters or carboxylic acids, which have no adverse effects on the environment and meet the development needs of ecological agriculture.

[0019] Preferably, in step S5, the reaction is carried out under inert gas protection, the reaction temperature is 50-80℃, the reaction time is 2-5h, and the pH value of the system is controlled to be maintained at 4.0-6.0 during the reaction process.

[0020] By adopting the technical scheme, in the reaction and integration link of step S5, the reaction is carried out under inert gas protection, the outside oxygen is isolated by the inert gas, oxidation degradation of active components such as complex amino acid and natural polysaccharide stabilizer is avoided, and at the same time, the valence change of trace elements is prevented. If the trace elements are oxidized to high valence, it will be difficult to form stable coordination bond with the carboxyl and amino groups of amino acid. The inert gas protection can ensure that the trace elements are in the appropriate chelation valence, and then ensure the structural stability and reaction activity of each component in the reaction system. The reaction temperature can provide sufficient energy for the chelation reaction, promote the efficient coordination and combination of carboxyl and amino groups in amino acid molecules with trace element ions such as boron and zinc, and at the same time, the structure of the slow-release carrier material will not be damaged or the amino acid will not be decomposed due to too high temperature. The reaction time can ensure that the chelation reaction is sufficient, so that the free nutrient components in the system are fully converted into stable chelate structure, and the residual unreacted components do not affect the product performance. The pH value of the system is controlled during the reaction process, which can accurately control the dissociation state of the amino acid molecules, expose the carboxyl and amino groups, optimize the coordination environment of the trace element ions, and promote the formation of stable chelates; at the same time, the pH condition is suitable for the growth environment of the subsequent crop roots, which creates favorable conditions for the accurate release of subsequent nutrients in the crop root area. In this process, the slow-release carrier material can simultaneously encapsulate the formed chelates, further lock the nutrients, and realize the efficient integration of the pretreated raw materials and the functional compound solution.

[0021] Preferably, in step S6, the temperature of the low-temperature concentration is 45-65℃, and the concentration is carried out under the condition that the absolute pressure is 10-30kPa, the free amino acid content reaches 100-150g / L, and the total content of zinc and boron is 15-25g / L; the cooling treatment is to cool the concentrated material to 25-35℃; the filtration adopts a membrane filtration system, and the filtration precision is 0.1-1.0μm.

[0022] By adopting the technical scheme, in the post-processing link of step S6, the filtration adopts a membrane filtration system, which can accurately intercept the unreacted impurities generated in the reaction process, including uncompletely dispersed inorganic mineral particles, unreacted raw material residues, and small particles and agglomerates, while allowing the target nutrient components, including amino acid chelates and slow-release carrier-nutrient complexes, to pass through smoothly, thereby ensuring the uniformity and purity of the subsequent concentration and finished product system, and the mild filtration mode of the membrane filtration will not damage the structure of the active components in the finished product. In the low-temperature concentration process, the low-temperature environment can avoid the problems of degradation of active components such as breaking of peptide bonds of complex amino acids and destruction of slow-release carrier material structure, and the reduced pressure condition can reduce the water evaporation temperature, thereby accelerating the concentration efficiency under the premise of ensuring the activity; the concentration end point can adjust the nutrient concentration of the finished product, thereby ensuring the rationality of the nutrient proportioning of the finished product and avoiding the disintegration of chelates or the agglomeration of the system caused by excessively high concentration. The cooling treatment cools the concentrated material to an appropriate temperature, which can make the chelate structure in the material system stable and formed, thereby reducing the performance changes such as phase separation and stratification caused by temperature fluctuations in the subsequent storage process; at the same time, the viscosity of the cooled material is moderate, which provides an appropriate physical state for the packaging, transportation and subsequent application mode of the finished product, including dilution spraying and drip irrigation, thereby ensuring the consistency and stability of the quality of the finished product.

[0023] Preferably, in the method, the additives for chelation or stabilization are only the natural polysaccharide stabilizer and the slow-release carrier material, and no chemical synthetic chelating agent and stabilizer is additionally added.

[0024] By adopting the technical scheme, the method only relies on the natural polysaccharide stabilizer and the slow-release carrier material to realize the chelation and stabilization functions, and no chemical synthetic chelating agent and stabilizer is additionally introduced. The two materials form clear functional division and cooperation: the natural polysaccharide stabilizer forms coordination combination with trace elements through the active sites in the molecular structure, directly realizes the chelation function, and maintains the system dispersion stability by means of the steric hindrance effect; the slow-release carrier material realizes nutrient slow-release regulation, and the functional groups on the surface of the slow-release carrier material can form secondary wrapping or adsorption with the amino acid-trace element chelate, thereby assisting to enhance the stability of the chelate structure. The two materials cooperatively play the chelation and stabilization roles, and the stable system structure can be constructed without relying on chemical synthetic additives, thereby avoiding the problems of antagonism between the chemical synthetic chelating agent and the natural components in the system or the system compatibility problem caused by the stabilizer residue, and reducing the potential influence of chemical substance residue on the soil environment and crops. The design is deeply cooperated with the physical barrier construction and the reaction process parameter regulation, the physical barrier reduces the nutrient exposure, the process parameter ensures the full chelation reaction, and the three together ensure that the product can still maintain good chelation effect and storage stability without additional chemical additives.

[0025] In summary, the present application has the following beneficial effects: 1、The application adopts a synergistic technical solution of constructing a physical barrier, a steric hindrance stabilizing layer and introducing a slow-release carrier material, cooperates with the whole process parameter regulation of raw material pretreatment, reaction synthesis and integration and post-treatment, and only uses natural polysaccharide stabilizers and slow-release carrier materials as chelating or stabilizing additives, avoids additional addition of chemically synthesized chelating agents and stabilizers, so that the amino acid liquid fertilizer system forms a stable structure, simultaneously realizes the orderly regulation of nutrient release, and achieves the effect of giving consideration to system stability and controllability of nutrient release.

[0026] 2、In the application, the enzymatic liquid or fermentation liquid derived from plant protein is preferably used as a complex amino acid, which is matched with trace elements containing boron and zinc and humic acid synergist, the content range and addition form of each component are determined, the compatibility between raw material components is improved, high-quality material basis is provided for subsequent reaction synthesis, and the effect of optimizing product nutrient composition is achieved.

[0027] 3、The method of the application controls the linear speed and processing time of high-speed shearing by limiting the type, particle size and addition amount of inorganic mineral materials, ensures that the first dispersion treatment is sufficient, and makes the material pre-dispersion liquid form a uniform and stable physical barrier, so that the effect of strengthening the physical isolation of the system is achieved.

[0028] 4、The method of the application controls the reaction temperature, time and system pH value under the protection of inert gas, makes the pretreated raw materials and functionalized complex liquid fully react and integrate, and at the same time, through specific condition filtration, low-temperature concentration and cooling treatment, the amino acid chelation reaction is completely ensured and the product quality is stable, the controllability of product preparation and the quality of finished product are improved.

[0029] 5、In the application, the pH-sensitive microcapsule or enzymatic polymer microsphere is preferably used as a slow-release carrier material, the specific material and structural characteristics thereof are determined, and the rotation speed and time of mixing treatment are controlled to make the slow-release carrier material fully integrate with the complex stabilizer solution, so that the effect of precisely regulating the nutrient release characteristics is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flow chart of an amino acid liquid fertilizer production method provided by the application. DETAILED DESCRIPTION

[0031] The application will be further described in detail in combination with examples and comparative examples, wherein the experimental methods used below are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained or prepared according to the literature method by those skilled in the art.

[0032] Technical concept: In related technologies, amino acid liquid fertilizer generally has the dual problems of insufficient system stability and poor nutrient release controllability. The core reason is that the traditional preparation process mostly adopts a simple raw material compounding mode, lacks coordinated design for system stability, does not establish an effective protective structure to block the erosion of nutrients by the external environment, and does not introduce a control component with environmental response characteristics, resulting in the inability of nutrient release rhythm to match the crop growth demand; in addition, some schemes rely on chemical synthesis of chelating agents and stabilizers, which can easily cause antagonism between system components, poor compatibility, and other problems, and the selection and ratio of raw materials and the process parameter control lack precision, further exacerbating the problems of system stratified precipitation, nutrient loss or release imbalance.

[0033] The technical solution solves the above problems through multi-dimensional coordinated technical means. The core is to build a composite control system combining physical barriers, steric hindrance stabilization layers, and environmental response carriers. Physical isolation protection is formed by dispersing specific inorganic mineral materials, a steric hindrance network is constructed by pairing natural polysaccharide stabilizers, and the system stability is synergistically enhanced. The pH-sensitive or enzymatic slow-release carrier is introduced to precisely control the nutrient release rhythm. At the same time, the raw material pretreatment process is optimized, the adaptability of the raw material components and forms is selected, and the parameters such as inert gas protection, temperature, and pH value in the reaction process are precisely controlled. The filtration, concentration, and cooling conditions of post-processing are also controlled. Only natural polysaccharide stabilizers and slow-release carriers are used to achieve chelation and stabilization, without the need for additional chemical synthetic additives. From the aspects of structure construction, raw material adaptation, and whole-process process control, the system stability and nutrient release controllability are synergistically optimized.

[0034] Embodiment 1: The embodiment provides a method for preparing an amino acid liquid fertilizer, comprising the following steps: S1, raw material pretreatment: providing raw materials comprising complex amino acids, trace elements, potassium salts, and synergistic agents; Among them, the complex amino acids are derived from plant protein enzymatic hydrolysate, and the free amino acid content is 150 g / L; the synergistic agent includes humic acid, and the final concentration in the reaction system is 35 g / L; the trace elements include boron and zinc, which are added in the form of soluble salts.

[0035] S2, constructing a physical barrier: adding silicon dioxide into a dispersion medium and performing first dispersion treatment under high-speed shearing conditions to obtain a material pre-dispersion liquid; Among them, the particle size D 90 of the silicon dioxide is 50-150 nm, and the addition amount is 0.8% of the mass of the complex amino acids; the linear speed of high-speed shearing is 22.5 m / s, and the treatment time is 50 min.

[0036] S3, constructing a steric hindrance stabilization layer: adding a chitosan derivative into the material pre-dispersion liquid and performing second dispersion treatment to form a composite stabilizer solution; The temperature of the second dispersion treatment is 50℃; and the amount of the chitosan derivative added is 1.25% of the mass of the complex amino acid.

[0037] S4, introducing an environment-responsive carrier: providing pH-sensitive microcapsules, mixing the pH-sensitive microcapsules with the complex stabilizer solution to form a functionalized complex solution; The capsule wall material of the pH-sensitive microcapsules is an acrylic resin copolymer; the stirring speed of the mixing treatment is 100 r / min, and the mixing time is 60 min.

[0038] S5, reaction synthesis and integration: putting the pretreated raw material in step S1 and the functionalized complex solution obtained in step S4 into a reaction kettle for reaction to form an amino acid chelate solution; The reaction is carried out under inert gas protection, the reaction temperature is 65℃, the reaction time is 3.5h, and the pH value of the system is controlled to be 5.0 during the reaction.

[0039] S6, post-treatment and finished product: the reaction completed amino acid chelate solution is sequentially filtered, low-temperature concentrated and cooled to obtain an amino acid liquid fertilizer finished product; The low-temperature concentration is carried out at a temperature of 55℃ under an absolute pressure of 20kPa, and the concentration is carried out until the free amino acid content reaches 125g / L and the total content of zinc and boron is 20g / L; the cooling treatment is to cool the concentrated material to 30℃; the filtration is carried out by using a membrane filtration system, and the filtration precision is 0.55μm.

[0040] The additives for chelation or stabilization are only natural polysaccharide stabilizers and slow-release carrier materials, and no chemical synthetic chelating agents and stabilizers are additionally added.

[0041] Embodiment 2: The amino acid liquid fertilizer production method provided by the embodiment comprises the following steps: S1, raw material pretreatment: providing raw materials containing complex amino acid, trace element, potassium salt and synergist; The complex amino acid is derived from plant protein fermentation liquor, and the free amino acid content is 100g / L; the synergist includes humic acid, and the final concentration of the humic acid in the reaction system is 20g / L; the trace element includes boron and zinc, which are added in the form of soluble salt.

[0042] S2, constructing a physical barrier: adding montmorillonite into a dispersion medium to carry out a first dispersion treatment under high-speed shearing to obtain a material pre-dispersion liquid; The particle size D 90 of the montmorillonite is 50-150nm, the amount of the montmorillonite added is 0.1% of the mass of the complex amino acid; the linear speed of the high-speed shearing is 15m / s, and the treatment time is 40min.

[0043] S3, constructing a steric hindrance stabilizing layer: adding sodium alginate to the material pre-dispersion liquid to perform a second dispersion treatment to form a composite stabilizer solution; The temperature of the second dispersion treatment is 40°C, and the amount of sodium alginate added accounts for 0.5% of the mass of the composite amino acid.

[0044] S4, introducing an environmental response carrier: providing enzyme-degraded polymer microspheres, mixing the enzyme-degraded polymer microspheres with the composite stabilizer solution to form a functional composite liquid; The material of the enzyme-degraded polymer microspheres is a polyester macromolecule, and the main chain of the polyester macromolecule contains a chemical bond that can be specifically cut by a phosphatase secreted by a plant root system. The stirring speed of the mixing treatment is 50 r / min, and the mixing time is 30 min.

[0045] S5, reaction synthesis and integration: putting the raw material pretreated in step S1 and the functional composite liquid obtained in step S4 into a reaction kettle to perform a reaction to form an amino acid chelate solution; The reaction is performed under the protection of an inert gas, the reaction temperature is 50°C, the reaction time is 2 h, and the pH value of the system is controlled to be maintained at 4.0 during the reaction process.

[0046] S6, post-treatment and finished product: sequentially performing filtration, low-temperature concentration, and cooling treatment on the amino acid chelate solution after the reaction is completed, and finally obtaining an amino acid liquid fertilizer finished product; The temperature of the low-temperature concentration is 45°C, and the concentration is performed under the condition that the absolute pressure is 10 kPa, the concentration is performed until the free amino acid content reaches 100 g / L, and the total content of zinc and boron is 15 g / L. The cooling treatment is to cool the concentrated material to 25°C. The filtration is performed by using a membrane filtration system, and the filtration precision is 0.1 μm.

[0047] The additives used for chelation or stabilization are only natural polysaccharide stabilizers and slow-release carrier materials, and no chemical synthetic chelating agents and stabilizers are additionally added.

[0048] Embodiment 3: The embodiment provides a method for preparing an amino acid liquid fertilizer, which comprises the following steps: S1, raw material pretreatment: providing raw materials containing composite amino acids, trace elements, potassium salts, and synergists; The composite amino acid is derived from a plant protein enzyme-degraded liquid, and the free amino acid content is 200 g / L. The synergist includes humic acid, and the final concentration of the humic acid in the reaction system is 50 g / L. The trace elements include boron and zinc, and the trace elements are added in the form of soluble salts.

[0049] S2, constructing a physical barrier: adding a hydrotalcite to a dispersion medium to perform a first dispersion treatment under high-speed shearing conditions to obtain a material pre-dispersion liquid; wherein the hydrotalcite particle size D is 50-150 nm 90 The distribution range is 50-150 nm, and the additive amount is 1.5% of the mass of the composite amino acid; the linear speed of high-speed shearing is 30 m / s, and the treatment time is 60 min.

[0050] S3, constructing a steric hindrance stabilizing layer: adding xanthan gum to the material pre-dispersion liquid, performing second dispersion treatment, and forming a composite stabilizer solution; wherein the temperature of the second dispersion treatment is 60°C; and the xanthan gum additive amount is 2.0% of the mass of the composite amino acid.

[0051] S4, introducing an environmental response carrier: providing pH-sensitive microcapsules, mixing the pH-sensitive microcapsules with the composite stabilizer solution, and forming a functionalized composite liquid; wherein the capsule wall material of the pH-sensitive microcapsules is a cellulose derivative; the stirring speed of the mixing treatment is 150 r / min, and the mixing time is 90 min.

[0052] S5, reaction synthesis and integration: putting the pretreated raw material in step S1 and the functionalized composite liquid obtained in step S4 into a reaction kettle together for reaction, and forming an amino acid chelate solution; wherein the reaction is carried out under inert gas protection, the reaction temperature is 80°C, the reaction time is 5 h, and the pH value of the system is controlled to be maintained at 6.0 during the reaction.

[0053] S6, post-treatment and finished product: sequentially performing filtration, low-temperature concentration, and cooling treatment on the reaction completed amino acid chelate solution, and finally obtaining an amino acid-containing liquid fertilizer finished product; wherein the low-temperature concentration is carried out at a temperature of 65°C under an absolute pressure of 30 kPa, and the concentration is carried out to the free amino acid content of 150 g / L and the total content of zinc and boron of 25 g / L; the cooling treatment is to cool the concentrated material to 35°C; the filtration is carried out by using a membrane filtration system, and the filtration precision is 1.0 μm.

[0054] wherein the additives for chelation or stabilization are only natural polysaccharide stabilizers and slow-release carrier materials, and no chemical synthetic chelating agents and stabilizers are additionally added.

[0055] Comparative Example 1: The only difference between the comparative example 1 and the example 1 is that step S2 is omitted, no nano-silicon dioxide is added, and the pretreated raw material after step S1 is directly mixed with the composite stabilizer solution prepared in step S3, and then enters step S5.

[0056] Comparative Example 2: The only difference between the comparative example 2 and the example 1 is that step S3 is omitted, no chitosan derivative is added, and the nano-material pre-dispersion liquid prepared in step S2 is directly mixed with the slow-release carrier material, and then enters step S5.

[0057] Comparative Example 3: The only difference between this comparative example and Example 1 is that no pH-sensitive microcapsules are added in step S4, and only the composite stabilizer solution prepared in step S3 is directly put into the reaction kettle with the pretreated raw material in step S1 for the reaction in step S5.

[0058] Comparative Example 4: The only difference between this comparative example and Example 1 is that in step S3, an equimolar amount of ethylenediaminetetraacetic acid is used instead of chitosan derivatives as a stabilizer.

[0059] I. Product stability test According to the relevant requirements of the stability test in GB / T23349-2020 “Ecological indicators of arsenic, cadmium, lead, chromium, and mercury in fertilizers” and the liquid fertilizer stability evaluation specification in the agricultural industry, 500 mL of the amino acid liquid fertilizer product prepared in each example and comparative example is taken and placed in a transparent sealed container, and at the same time, it is placed in a 4°C low-temperature environment, a 40°C high-temperature environment, and a 25°C room temperature environment for storage for 12 months. During the period, the sample is observed and recorded for stratification, precipitation, discoloration, and other phenomena at the end of the 3rd month, 6th month, 9th month, and 12th month. The retention rate of free amino acids in the sample at each time node is determined by ultraviolet spectrophotometry, wherein the retention rate of free amino acids = (free amino acid content after storage / initial free amino acid content) x 100%, and the longest storage time without obvious stratification and precipitation of the sample is recorded, thereby comprehensively evaluating the long-term stability and anti-degradation ability of the product.

[0060] II. Nutrient slow-release performance test According to NY / T1974-2010 “Determination of amino acid content in water-soluble fertilizers” and the slow-release performance test method simulating the crop root environment, 100 mL of the product prepared in each example and comparative example is taken and added to 500 mL of a buffer solution simulating the crop root exudate environment. The buffer solution has a pH of 5.5-7.0 and contains phosphatase secreted by plant roots. The mixture is placed in a 25°C constant-temperature shaking incubator and shaken at a speed of 150 r / min. Samples are taken after 12 hours, 24 hours, 48 hours, and 72 hours of shaking. The release amounts of zinc and boron elements in the solution are determined by inductively coupled plasma emission spectrometry, and the release amount of amino acids is determined by the Kjeldahl method. The cumulative release rate of nutrients at each time node = (cumulative release nutrient mass / total nutrient mass in the sample) x 100%. By comparing the nutrient release rates at different time nodes and the 48-hour cumulative release rate, the environmental response type slow-release effect of the product is evaluated.

[0061] III. Crop nutrient utilization rate test Tomato was selected as the test crop according to NY / T1115-2020 “Technical Specification for Fertilizer Effect Identification Field Test”, and a field plot test was set up. Each embodiment and comparative example corresponded to 3 repeated plots, and the plot area was 15 m 2 The isolation rows were set between plots, and the cultivation and management measures were consistent. Each plot was sprayed with the corresponding liquid fertilizer product by leaf surface and root drip irrigation, and the fertilizer amount was uniformly converted to 0.3 kg of nitrogen per plot, which was applied in three times, respectively at the seedling stage, flowering stage and fruiting stage. At the same time, a blank control group without the liquid fertilizer was set. After the tomato was harvested, the total yield of the tomato in each plot was determined, and the contents of nitrogen, zinc and boron elements in the tomato fruit were determined by Kjeldahl nitrogen determination and atomic absorption spectrophotometry, respectively. Among them, the nutrient utilization rate = (total amount of nutrient absorbed by crops / total amount of nutrient brought by fertilization) x 100%, and the actual application effect and nutrient utilization efficiency advantage of the product were comprehensively evaluated by comparing the tomato yield and nutrient utilization rate of each embodiment and comparative example.

[0062] The performance test data of the amino acid liquid fertilizer of each embodiment and comparative example are shown in Table 1.

[0063] Table 1:

[0064] It can be seen from the combination of Examples 1-3 and Comparative Example 1 and Table 1 that the addition of inorganic mineral materials and the construction of physical barriers have a synergistic effect with the natural polysaccharide stabilizer. This synergistic effect reduces the contact of amino acids with the external environment through physical isolation, inhibits the degradation of amino acids and the aggregation of the system, and regulates the release rate of nutrients. Without this step, the system loses physical isolation protection, the degradation path of amino acids increases, the aggregation phenomenon is easy to occur, and the release of nutrients is not affected by physical barriers, and the release pattern changes.

[0065] It can be seen from the combination of Examples 1-3 and Comparative Example 2 and Table 1 that the addition of natural polysaccharide stabilizer and the construction of steric hindrance stabilizing layer have a synergistic effect with physical barriers and environment-responsive carriers. The natural polysaccharide stabilizer prevents particle aggregation through intermolecular steric hindrance effect, and provides dispersion support for physical barriers and environment-responsive carriers, so that the three form a stable composite system. After omitting this step, the steric hindrance effect of the system disappears, the interparticle force is not inhibited, the aggregation tendency is enhanced, the binding force of nutrients in the system is weakened, and the release rate is accelerated.

[0066] It can be seen from Examples 1-3 and Comparative Example 3 in combination with Table 1 that the addition of the environment-responsive carrier is synergistic with the physical barrier and the steric hindrance stabilizing layer. The environment-responsive carrier responds to environmental conditions through its structural characteristics, and then regulates the opening and closing of the nutrient release channel, in combination with the blocking effect of the physical barrier and the dispersion effect of the steric hindrance stabilizing layer, to achieve orderly regulation of nutrient release. When this link is missing, the nutrient release channel is not regulated by the environment, and is only affected by physical diffusion, the release process has no order, and the nutrients quickly leave the system.

[0067] It can be seen from Examples 1-3 and Comparative Example 4 in combination with Table 1 that there are differences in the synergistic adaptability of natural polysaccharide stabilizers and chemically synthesized stabilizers with the physical barrier and the environment-responsive carrier. The molecular structure of the natural polysaccharide stabilizer has a higher degree of matching with the surface characteristics of the physical barrier material and the environment-responsive carrier, can form a more stable interface combination, and then maintain the overall stability of the system and regulate nutrient release. After using a chemically synthesized stabilizer instead, the molecular structure has insufficient interface bonding force with other components, cannot form a stable synergistic system, and the stability of the system and the ability to regulate nutrient release change.

[0068] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and as long as the modifications are within the scope of the claims of the present application, they are protected by the Patent Law.

Claims

1. A method for producing an amino acid liquid fertilizer, characterized in that: Includes the following steps: S1. Raw material pretreatment: Provide raw materials containing compound amino acids, trace elements, potassium salts and synergists; S2. Constructing a physical barrier: Inorganic mineral materials are added to the dispersion medium and subjected to the first dispersion treatment under high-speed shear conditions to obtain a pre-dispersion liquid of the material. S3. Constructing a steric stabilizing layer: Add a natural polysaccharide stabilizer to the pre-dispersion liquid of the material and perform a second dispersion treatment to form a composite stabilizer solution; S4. Introducing an environmentally responsive carrier: Providing a sustained-release carrier material, which is then mixed with a composite stabilizer solution to form a functionalized composite liquid; S5. Reaction Synthesis and Integration: The pretreated raw materials in step S1 and the functionalized composite liquid obtained in step S4 are put into the reaction vessel to react and form an amino acid chelate liquid. S6. Post-processing and finished product: The amino acid chelate solution after the reaction is completed is filtered, concentrated at low temperature and cooled in sequence to finally obtain the finished product containing amino acids as liquid fertilizer.

2. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S1, the compound amino acids are derived from the enzymatic hydrolysate or fermentation broth of plant protein, and the free amino acid content is 100-200 g / L; the synergist includes humic acid, and its final concentration in the reaction system is 20-50 g / L; the trace elements include boron and zinc, which are added in the form of soluble salts.

3. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S2, the inorganic mineral material is at least one of silica, montmorillonite, or hydrotalcite, and its particle size D 90 The distribution range is 50-150nm, and the addition amount is 0.1-1.5% of the mass of the composite amino acids; the linear velocity of the high-speed shearing is 15-30m / s, and the processing time is 40-60min.

4. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S3, the temperature of the second dispersion treatment is 40-60℃; the natural polysaccharide stabilizer is selected from at least one of chitosan derivatives, sodium alginate or xanthan gum, and its addition amount accounts for 0.5-2.0% of the mass of the composite amino acids.

5. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S4, the sustained-release carrier material is at least one of pH-sensitive microcapsules or enzymatically hydrolyzed polymer microspheres; the stirring speed for the mixing process is 50-150 r / min, and the mixing time is 30-90 min.

6. The method for preparing an amino acid liquid fertilizer according to claim 5, characterized in that: The capsule wall material of the pH-sensitive microcapsules is an acrylic resin copolymer or a cellulose derivative.

7. The method for preparing an amino acid liquid fertilizer according to claim 5, characterized in that: The enzymatically hydrolyzed polymer microspheres are made of polyester polymers, and their main chain contains chemical bonds that can be specifically cleaved by phosphatases or ureases secreted by plant roots.

8. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S5, the reaction is carried out under inert gas protection, the reaction temperature is 50-80℃, the reaction time is 2-5h, and the pH value of the system is maintained at 4.0-6.0 during the reaction.

9. The method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In step S6, the low-temperature concentration is carried out at a temperature of 45-65℃ and an absolute pressure of 10-30kPa, until the free amino acid content reaches 100-150g / L and the total content of zinc and boron is 15-25g / L; the cooling treatment is to cool the concentrated material to 25-35℃; the filtration adopts a membrane filtration system with a filtration accuracy of 0.1-1.0μm.

10. A method for preparing an amino acid liquid fertilizer according to claim 1, characterized in that: In the method, the additives used for chelation or stabilization are only natural polysaccharide stabilizers and the sustained-release carrier material, without the addition of chemically synthesized chelating agents and stabilizers.

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