Preparation method of corn steep liquor fertilizer based on circulating membrane separation enhanced enzymolysis
By using a circulating membrane separation method to enhance enzymatic hydrolysis, the problems of high energy consumption and low enzymatic hydrolysis efficiency in the corn steep liquor fertilizer preparation process have been solved. This has enabled efficient utilization of enzymes and intelligent release of products, promoting the industrialization and market promotion of corn steep liquor fertilizer.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-04-10
AI Technical Summary
Existing methods for preparing fertilizer from corn steep liquor suffer from high energy consumption, low enzyme utilization efficiency, and high costs. Furthermore, the activity of proteases and other enzymes is significantly affected during conventional enzymatic hydrolysis, making it difficult to achieve industrialization and standardization.
By employing a circulating membrane separation enhanced enzymatic hydrolysis method, and by selecting appropriate membrane pore sizes and enzyme types, proteases are used separately from other enzymes. Combined with bioflocculants and ultrasonic treatment, this method achieves efficient enzyme retention and recovery, enabling the preparation of temperature-sensitive solid and liquid fertilizers. Product standards are then developed based on the characteristics of corn steep liquor.
It improves enzyme lifespan and hydrolysis efficiency, reduces enzyme input costs, realizes full utilization of corn steep liquor and product refinement, and the product release rate is related to changes in soil environment, adapting to crop growth needs and promoting industrialization.
Smart Images
Figure CN121824210A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing corn syrup fertilizer. Background Technology
[0002] Direct application of corn steep liquor presents challenges such as high viscosity, slow nutrient release, and potential presence of anti-nutritional factors like phytic acid. High-temperature, high-pressure hydrolysis is energy-intensive, while microbial fermentation is inefficient. Conventional enzymatic hydrolysis of corn steep liquor is a more promising method for resource utilization due to its low energy consumption and high activity of targeted enzymes. However, current methods suffer from low enzyme utilization efficiency and often involve co-using proteases with other enzymes, affecting their activity and ultimately increasing the cost of the enzymatic hydrolysis process.
[0003] For the industrialization of fertilizer production using corn steep liquor as a raw material, product standardization is crucial. Therefore, it is necessary to analyze the approximate standards based on the complex composition of corn steep liquor, determine the optimal compounding scheme to establish standardized products, save compounding costs, and achieve superior product benefits.
[0004] Therefore, there is an urgent need to develop efficient and low-consumption preparation methods for producing liquid fertilizer from corn steep liquor, so as to form commercially viable products that meet existing standards and promote its industrialization process. Summary of the Invention
[0005] The purpose of this invention is to solve the problem of the extensive and crude methods of existing corn steep liquor fertilizer preparation methods, and to provide a corn steep liquor fertilizer preparation method based on cyclic membrane separation and enhanced enzymatic hydrolysis.
[0006] The present invention discloses a method for preparing corn steep liquor fertilizer based on enhanced enzymatic hydrolysis using a circulating membrane separation process:
[0007] 1. The corn syrup is diluted using a high-speed shear homogenizer to obtain a homogenized liquid. The homogenized liquid is then subjected to ultrasonic pretreatment, followed by the addition of a bio-flocculator. After the reaction, coarse material is obtained.
[0008] 2. After adding enzyme A to the crude material, stock solution 1 is obtained. Stock solution 1 is pumped into the first membrane reactor. After circulating membrane separation, filtrate 1 and concentrate 1 are obtained respectively. The circulating membrane separation is as follows: after stock solution 1 is pumped into the first membrane reactor, it is filtered to obtain filtrate and concentrate. Then, the filtrate and concentrate are re-entered into the first membrane reactor for circulation. The circulation reaction is carried out for 0.5~4 hours to complete one round of circulating membrane separation, obtaining filtrate 1 and concentrate. Then, the concentrate is mixed with new stock solution 1 for a new round of circulating membrane separation. After 3~15 rounds of circulating membrane separation, concentrate 1 is obtained.
[0009] 3. Add enzyme B to filtrate 1 to obtain stock solution 2, then pump it into the second membrane reactor. After circulating membrane separation, filtrate 2 and concentrate 2 are obtained respectively. The circulating membrane separation is as follows: after stock solution 2 enters the second membrane reactor, it is filtered to obtain filtrate and concentrate. Then the filtrate and concentrate are re-entered into the second membrane reactor for circulation. After 2-6 hours of circulation reaction, one round of circulating membrane separation is completed, obtaining filtrate 2 and concentrate. The concentrate is mixed with new stock solution 2 for a new round of circulating membrane separation. After 5-20 rounds of circulating membrane separation, concentrate 2 is obtained.
[0010] IV. Add biochar and compound materials to concentrated liquid 1, stir evenly, dry, extrude and granulate to obtain solid fertilizer;
[0011] 5. Add concentrated liquid 2 to the compound materials to obtain liquid fertilizer.
[0012] Beneficial effects of this invention:
[0013] I. This invention achieves efficient retention and recovery of enzymes by selecting membranes with suitable pore sizes, realizing a circulating membrane separation process, improving the enzyme's lifespan, and helping to reduce enzyme input costs.
[0014] Second, this invention separates the protease from other enzymes, reducing the influence of the protease on other enzymes and thus improving the efficiency of enzymatic hydrolysis.
[0015] Third, this invention utilizes enhanced coagulation membrane separation combined with efficient enzymatic hydrolysis to separate high-molecular-weight and low-volume nutrients in corn steep liquor. The entire process generates no waste liquid or waste. Based on different absorption characteristics, it prepares high-molecular-weight, low-solubility, slow-degradable solid fertilizer and low-molecular-weight, highly soluble, and easily absorbed liquid fertilizer. This allows for the full utilization of corn steep liquor while making the products more refined and facilitating market promotion.
[0016] Fourth, this invention can form product standards according to the characteristics of corn steep liquor itself, save the cost of compounding agents, and is tailored to specific needs, which is conducive to industrialization and promotion.
[0017] V. The solid fertilizer synthesized subsequently in this invention exhibits a temperature-sensitive response, while the liquid fertilizer exhibits both temperature-sensitive and pH-sensitive responses. Specifically, the NIPAM unit provides temperature responsiveness (LCST -32-34℃), and the acrylic acid unit provides pH responsiveness (carboxylation / deprotonation). Through physical encapsulation and hydrogen bonding, small-molecule amino acids, peptides, sugars, and minerals in the concentrated solution are loaded into the hydrogel network. When the soil temperature is higher than the LCST of the hydrogel, the polymer chains hydrophobically shrink, compressing the network pores and "squeezing out" the contained nutrient solution, accelerating its release. As the temperature decreases, the gel swells, slowing the release. When the soil is acidic (pH < 6, such as in the rhizosphere environment of some acid-loving crops), the carboxylation of the acrylic acid segments weakens the polymer's hydrophilicity, causing the network to shrink and synergistically promoting nutrient release. Under neutral or alkaline conditions, the carboxyl groups ionize, and the electrostatic repulsion between the segments causes the network to swell, slowing the release. Conventional fertilizers, once applied to the soil, release their nutrients primarily based on their own properties. This often results in insufficient supply during peak crop nutrient demand periods, while leading to nutrient excess and loss during non-critical periods. This invention links the nutrient release rate of fertilizer granules to changes in the soil environment (such as pH and temperature), which are often synchronized with crop growth stages and root activity, thus more intelligently matching the dynamic needs of crops.
[0018] VI. This invention selects the low critical solution temperature (LCST) of poly(N-isopropylacrylamide) (PNIPAM) as 32-34℃ as the temperature response trigger point. The fundamental reason is that this temperature range highly coincides with the soil temperature variation range during the key growth stages of most crops. This aims to solve the problem of "thermal synchronization" between fertilizer nutrient release and crop physiological activities. Crop root activity and nutrient absorption rates are closely related to soil temperature, typically peaking within a suitable temperature range (e.g., 25-35℃ for many temperate crops). When soil temperature rises above 32-34℃, it often indicates that the crop is in a vigorous growth period with a strong demand for nutrients. At this time, the PNIPAM gel shrinks, opening the membrane pores and accelerating nutrient release to match the crop's high demand. Conversely, when the soil temperature is low, crop growth slows, demand decreases, and gel swelling automatically slows down release, avoiding nutrient waste. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the membrane reactor of the present invention;
[0020] Figure 2 This is a diagram of the potted plant experiment in Example 1. Detailed Implementation
[0021] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.
[0022] Specific Implementation Method 1: This implementation method describes a method for preparing corn steep liquor fertilizer based on enhanced enzymatic hydrolysis using a circulating membrane separation process.
[0023] 1. The corn syrup is diluted using a high-speed shear homogenizer to obtain a homogenized liquid. The homogenized liquid is then subjected to ultrasonic pretreatment, followed by the addition of a bio-flocculator. After the reaction, coarse material is obtained.
[0024] 2. After adding enzyme A to the crude material, stock solution 1 is obtained. Stock solution 1 is pumped into the first membrane reactor. After circulating membrane separation, filtrate 1 and concentrate 1 are obtained respectively. The circulating membrane separation is as follows: after stock solution 1 is pumped into the first membrane reactor, it is filtered to obtain filtrate and concentrate. Then, the filtrate and concentrate are re-entered into the first membrane reactor for circulation. The circulation reaction is carried out for 0.5~4 hours to complete one round of circulating membrane separation, obtaining filtrate 1 and concentrate. Then, the concentrate is mixed with new stock solution 1 for a new round of circulating membrane separation. After 3~15 rounds of circulating membrane separation, concentrate 1 is obtained.
[0025] 3. Add enzyme B to filtrate 1 to obtain stock solution 2, then pump it into the second membrane reactor. After circulating membrane separation, filtrate 2 and concentrate 2 are obtained respectively. The circulating membrane separation is as follows: after stock solution 2 enters the second membrane reactor, it is filtered to obtain filtrate and concentrate. Then the filtrate and concentrate are re-entered into the second membrane reactor for circulation. After 2-6 hours of circulation reaction, one round of circulating membrane separation is completed, obtaining filtrate 2 and concentrate. The concentrate is mixed with new stock solution 2 for a new round of circulating membrane separation. After 5-20 rounds of circulating membrane separation, concentrate 2 is obtained.
[0026] IV. Add biochar and compound materials to concentrated liquid 1, stir evenly, dry, extrude and granulate to obtain solid fertilizer;
[0027] 5. Add concentrated liquid 2 to the compound materials to obtain liquid fertilizer.
[0028] The compound material mentioned in step four of this embodiment is inorganic nutrients, pH adjuster, or microbial agent, and the addition amount is 0.5% to 10% of the dry matter. Depending on the compound material in step four, the solid fertilizer can be biochar-based organic fertilizer, bio-organic fertilizer, or compound microbial fertilizer; the compound material mentioned in step five is inorganic salt or amino acid, and the addition amount is 20 to 200 g / L; the liquid fertilizer can be water-soluble fertilizer containing amino acids, foliar fertilizer containing organic matter, water-soluble fertilizer containing medium elements, or water-soluble fertilizer containing trace elements.
[0029] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the ultrasonic frequency in step one is 20-40 kHz, the power density is 0.3-0.8 W / mL, and the action time is 2-5 min. Everything else is the same as in Specific Implementation Method One.
[0030] The weak ultrasonic treatment in this embodiment does not damage small molecule nutrients, but can effectively generate cavitation effect, breaking down protein micelles, fat globules and cell debris in corn steep liquor, significantly reducing the viscosity of the system, and allowing the encapsulated starch, protein and other substrates to be more fully exposed to the enzyme, thereby improving the overall enzymatic hydrolysis efficiency.
[0031] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: in step 1, the bioflocculant is one or a mixture of chitosan and polyglutamic acid, with an addition amount of 1~10 g / L and a reaction time of 10~60 min. Everything else is the same as in Specific Implementation Method 1 or 2.
[0032] This embodiment uses a bioflocculant, which helps to enrich poorly soluble proteins and reduces the probability of subsequent membrane clogging, thus reducing the frequency of membrane flushing. Furthermore, bioflocculants are commonly used high-value components in agricultural fertilizers, which is beneficial for improving the quality of solid fertilizers.
[0033] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that enzyme A in step two is an acidic protease, and the amount added is 0.5~6g / L. Everything else is the same as in Specific Implementation Methods One to Three.
[0034] The acidic protease selected in this embodiment is based on the characteristic of corn steep liquor with a pH of 3-5, which is conducive to the enzymatic hydrolysis effect.
[0035] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the molecular weight cutoff of the membrane in the first membrane reactor described in step two is 5~20 kDa. Everything else is the same as in Specific Implementation Methods One to Four.
[0036] In this embodiment, the membrane pore size corresponds to the protease, which can effectively recover the protease.
[0037] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step three, enzyme B is a mixture of phytase, pectinase, amylase, and acid phosphatase in a mass ratio of 1:1:1:1, and the amount added is 0.5~7 g / L. Everything else is the same as in Specific Implementation Methods One to Five.
[0038] In this embodiment, the enzyme selection corresponds to the corn steep liquor composition, which can effectively remove phytic acid resistance factors, convert inositol nutrients, reduce solution viscosity, improve quality, and reduce membrane fouling.
[0039] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the molecular weight cutoff of the membrane in the second membrane reactor described in step three is 500 Da. Everything else is the same as in Specific Implementation Methods One to Five.
[0040] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the method for preparing temperature-sensitive solid fertilizer using concentrated liquid 1 is as follows: biochar and compound materials are added to concentrated liquid 1 and stirred evenly to form a core material mixture; then, fluidized bed coating technology is used for coating, and the coated particles are dried to a moisture content of less than 30%, thus obtaining temperature-sensitive solid fertilizer; wherein the particle size of biochar is 20-100 mesh, and the mass ratio of biochar to concentrated liquid 1 is in the range of (0.05-0.2):1, and the coating material is poly(N-isopropylacrylamide) hydrogel. Everything else is the same as in Specific Implementation Methods One to Seven.
[0041] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that: the method for preparing temperature-sensitive and pH-sensitive dual-response liquid fertilizer using concentrated solution 2 is as follows: Concentrated solution 2 is added to the compound material, then N-isopropylacrylamide monomer and acrylic acid monomer are added to obtain a mixed solution; crosslinking agent N,N'-methylenebisacrylamide is added to the mixed solution at an amount of 0.5%-2.0% of the total monomer mass; subsequently, ammonium persulfate initiator is added at an amount of 0.5%-1.5% of the total monomer mass to obtain a mixed system; the mixed system is then placed in a closed reactor and reacted under an inert atmosphere, with the reaction temperature controlled at 60-70℃, continuously stirred, and the reaction time 2-6 hours to obtain the temperature-sensitive and pH-sensitive dual-response liquid fertilizer. Everything else is the same as in Specific Implementation Methods One through Eight.
[0042] Liquid fertilizers must meet the relevant standards for water-soluble fertilizers containing amino acids, foliar fertilizers containing organic matter, water-soluble fertilizers containing medium or micronutrients, etc.
[0043] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that, based on the volume of concentrated liquid 2, the amount of N-isopropylacrylamide monomer added is 5%-10% w / v, and the amount of acrylic acid monomer added is 1%-3% w / v. The rest is the same as Specific Implementation Methods 1 to 9.
[0044] The beneficial effects of the present invention are verified using the following embodiments:
[0045] Example 1: This example describes a method for preparing corn steep liquor fertilizer based on enhanced enzymatic hydrolysis using a circulating membrane separation process, comprising the following steps:
[0046] I. Using corn slurry from a starch factory in Shandong as raw material, the raw material was diluted 12 times using a high-speed shear homogenizer to obtain homogenized liquid. The homogenized liquid was then subjected to ultrasonic pretreatment, and a bio-flocculant was added. After reaction, coarse material was obtained. The added bio-flocculant was chitosan, with an addition amount of 2.5 g / L, and the addition amount of sodium alginate as a coagulant aid was 2.5 g / L. The reaction time was 60 min.
[0047] 2. Add acidic protease to the crude material at a concentration of 5.5 g / L to obtain stock solution 1. Pump stock solution 1 into the first membrane reactor. After circulating membrane separation, filtrate 1 and concentrate 1 are obtained. The circulating membrane separation is as follows: after stock solution 1 is pumped into the first membrane reactor, it is filtered to obtain filtrate and concentrate. Then, the filtrate and concentrate are re-entered into the first membrane reactor for circulation. The circulation reaction is carried out for 4 hours to complete one round of circulating membrane separation, obtaining filtrate 1 and concentrate. Then, the concentrate is mixed with new stock solution 1 for a new round of circulating membrane separation. After 5 rounds of circulating membrane separation, concentrate 1 is obtained. The membrane molecular weight cutoff is 10 kDa.
[0048] 3. Add enzyme B to filtrate 1 to obtain stock solution 2, then pump it into a second membrane reactor with a molecular weight cutoff of 500 Da. After circulating membrane separation, filtrate 2 and concentrate 2 are obtained respectively. The circulating membrane separation is as follows: after stock solution 2 enters the second membrane reactor, it is filtered to obtain filtrate and concentrate. Then the filtrate and concentrate are re-entered into the second membrane reactor for circulation. After 6 hours of circulation reaction, one round of circulating membrane separation is completed, obtaining filtrate 2 and concentrate. The concentrate is mixed with new stock solution 2 for a new round of circulating membrane separation. After 10 rounds of circulating membrane separation, concentrate 2 is obtained. Enzyme 2 is a mixture of phytase, pectinase, amylase and acid phosphatase, with an addition amount of 7 g / L.
[0049] IV. Add biochar and compound materials to concentrated liquid 1, stir evenly, dry, extrude and granulate to obtain biochar-based organic fertilizer; wherein the biochar particle size is 35 mesh, and the mass ratio of biochar to concentrated liquid 1 is 0.1:1; the compound material is potassium hydroxide, and the amount added is 2.5% of the dry matter, and the moisture content after drying is less than 30%. It meets the standard for biochar-based organic fertilizer.
[0050] 5. Add concentrated solution 2 to the compound material, heat to 40℃, and react for 4 hours to obtain a water-soluble fertilizer containing amino acids. The compound material is a soluble calcium and magnesium salt, added at 140 g / L, and amino acids at 3.8 g / L. The liquid fertilizer meets the standard for water-soluble fertilizers containing amino acids.
[0051] The remaining filtrate 2 is returned to the corn steep liquor dilution step for reuse. Figure 1 This is a schematic diagram of a membrane reactor.
[0052] The fertilizer prepared in this embodiment was tested, and the main indicator data are as follows:
[0053] Table 1. Biochar-based organic fertilizers
[0054]
[0055] Table 2. Water-soluble fertilizers containing amino acids
[0056]
[0057] The prepared amino acid-containing water-soluble fertilizer and the commercially available water-soluble fertilizer were diluted 500 times respectively, and then used to plant Chinese cabbage. During the same growth cycle, the experimental group produced more seedlings and exhibited better growth, indicating that it has a good planting effect (see...). Figure 2 ).
[0058] Example 2 This example describes a method for preparing corn steep liquor fertilizer based on enhanced enzymatic hydrolysis using a circulating membrane separation process, comprising the following steps:
[0059] I. Using corn slurry from a starch factory in Shandong as raw material, the raw material was diluted 12 times using a high-speed shear homogenizer to obtain homogenized liquid. The homogenized liquid was then subjected to ultrasonic pretreatment, and a bio-flocculant was added. After reaction, coarse material was obtained. The added bio-flocculant was chitosan, with an addition amount of 2.5 g / L, and the addition amount of sodium alginate as a coagulant aid was 2.5 g / L. The reaction time was 60 min.
[0060] 2. Add acidic protease to the crude material at a concentration of 5.5 g / L to obtain stock solution 1. Pump stock solution 1 into the first membrane reactor. After circulating membrane separation, filtrate 1 and concentrate 1 are obtained. The circulating membrane separation is as follows: after stock solution 1 is pumped into the first membrane reactor, it is filtered to obtain filtrate and concentrate. Then, the filtrate and concentrate are re-entered into the first membrane reactor for circulation. The circulation reaction is carried out for 4 hours to complete one round of circulating membrane separation, obtaining filtrate 1 and concentrate. Then, the concentrate is mixed with new stock solution 1 for a new round of circulating membrane separation. After 5 rounds of circulating membrane separation, concentrate 1 is obtained. The membrane molecular weight cutoff is 10 kDa.
[0061] 3. Add enzyme B to filtrate 1 to obtain stock solution 2, then pump it into a second membrane reactor with a molecular weight cutoff of 500 Da. After circulating membrane separation, filtrate 2 and concentrate 2 are obtained respectively. The circulating membrane separation is as follows: after stock solution 2 enters the second membrane reactor, it is filtered to obtain filtrate and concentrate. Then the filtrate and concentrate are re-entered into the second membrane reactor for circulation. After 6 hours of circulation reaction, one round of circulating membrane separation is completed, obtaining filtrate 2 and concentrate. The concentrate is mixed with new stock solution 2 for a new round of circulating membrane separation. After 10 rounds of circulating membrane separation, concentrate 2 is obtained. Enzyme 2 is a mixture of phytase, pectinase, amylase and acid phosphatase, with an addition amount of 7 g / L.
[0062] IV. Add biochar and compound materials to concentrated liquid 1, stir evenly, dry, extrude and granulate to obtain compound microbial fertilizer; wherein the biochar particle size is 35 mesh, and the mass ratio of biochar to concentrated liquid 1 is 0.06:1; the compound materials are 3.5% potassium hydroxide and 0.1% Bacillus subtilis, and the moisture content after drying is less than 30%. It meets the standard for compound microbial fertilizer.
[0063] 5. Add concentrated liquid 2 to the compound material, heat to 40℃, and react for 4 hours to obtain a foliar fertilizer containing organic matter; the compound material consists of a micronutrient mixture of 50 g / L and urea of 15 g / L. The liquid fertilizer meets the standard for foliar fertilizer containing organic matter.
[0064] The fertilizer prepared in this embodiment was tested, and the main indicator data are as follows:
[0065] Table 3. Standards for Compound Microbial Fertilizers
[0066]
[0067] Table 4. Foliar Fertilizers Containing Organic Matter
[0068]
[0069] Example 3: This example describes a method for preparing temperature-sensitive solid fertilizer using concentrated liquid 1. The biochar-based organic fertilizer prepared in Example 1 is used as the core material mixture. Then, fluidized bed coating technology is used for coating, and the coated particles are dried to a moisture content below 30%, thus obtaining the temperature-sensitive solid fertilizer. The biochar particle size is 20-100 mesh, and the mass ratio of the biochar to concentrated liquid 1 is (0.05-0.2):1. The coating material is poly(N-isopropylacrylamide) hydrogel.
[0070] The response characteristics of the prepared temperature-sensitive solid fertilizer were tested. The solid fertilizer prepared in Example 1 was used as control group 1, and the commercially available solid fertilizer was used as control group 2. The above fertilizers were applied to homogeneous soil and placed in an incubator with precise temperature control.
[0071] The cumulative nitrogen release rate of different solid fertilizers during a 28-day incubation period was tested at different temperatures. Test conditions: neutral soil, static incubation. Data are shown in Table 5.
[0072] Table 5
[0073]
[0074] Table 6 shows the comparison of the initial nutrient leaching rate of solid fertilizer within 7 days at different temperatures. Test conditions: simulated rainfall leaching.
[0075] Table 6
[0076]
[0077] As shown in Tables 5 and 6, the nutrient release rate of the solid fertilizer increases significantly and regularly with increasing temperature, indicating that its coating material has a clear temperature response. Although the solid fertilizer of this invention releases nutrients more rapidly at high temperatures (35°C), its nutrient leaching rate is still significantly lower than that of rapidly released solid fertilizers under the same conditions. This proves that it can significantly reduce nutrient loss while improving effective fertilization. Although commercially available coated fertilizers have a certain slow-release effect, their release behavior is not sensitive to temperature changes and cannot achieve intelligent fertilization synchronized with crop growth heat.
[0078] Example 4: The method for preparing a temperature-sensitive and pH-sensitive dual-response liquid fertilizer using concentrated solution 2 in this example is as follows: The amino acid-containing water-soluble fertilizer from Example 1 is used as the reaction matrix and nutrient mother liquor. Then, N-isopropylacrylamide monomer and acrylic acid monomer are added to obtain a mixed solution. A crosslinking agent, N,N'-methylenebisacrylamide, is added to the mixed solution at an amount of 0.5%-2.0% of the total monomer mass. Subsequently, an initiator, ammonium persulfate, is added at an amount of 0.5%-1.5% of the total monomer mass to obtain a mixed system. The mixed system is then placed in a closed reactor and reacted under an inert atmosphere at a temperature controlled at 60-70°C with continuous stirring for 2-6 hours to obtain the temperature-sensitive and pH-sensitive dual-response liquid fertilizer. Based on the volume of concentrated solution 2, the amount of N-isopropylacrylamide monomer added is 5%-10% w / v, and the amount of acrylic acid monomer added is 1%-3% w / v.
[0079] The response characteristics of the prepared temperature- and pH-sensitive dual-response liquid fertilizer were tested. The amino acid-containing water-soluble fertilizer of Example 1 was used as control group 1, and the commercially available liquid fertilizer was used as control group 2.
[0080] A static immersion method was used, with each group placed in a series of constant-temperature shaking flasks containing buffer solutions of different pH values (e.g., pH 5.0, 7.0). Temperature gradients (e.g., 25℃, 35℃) were set to cover the low critical solution temperature (LCST) range of the materials. The cumulative nitrogen release rate of different liquid fertilizers over 72 hours was calculated under in vitro simulation conditions (Table 7).
[0081] Table 7
[0082]
[0083] As shown in Table 7, the liquid fertilizer in this embodiment released the fastest under acidic (pH 5.0) and high-temperature (35°C) conditions, significantly higher than under other conditions and the control group, demonstrating its dual pH / temperature response characteristics. In contrast, the liquid fertilizer release in Example 1 was not affected by environmental regulation, and the commercially available liquid fertilizer showed a weak response.
[0084] A pot experiment was conducted using the above-mentioned liquid fertilizer. The growth period was 60 days. Growth and physiological indicators were measured, and the plant biomass and nitrogen fertilizer utilization rate of different fertilizer treatments were calculated (see Table 8).
[0085] Table 8
[0086]
[0087] As shown in Table 8, the biomass, nitrogen uptake, and nitrogen fertilizer utilization rate of the Chinese cabbage treated with the liquid fertilizer of this invention were significantly higher than those of all control groups. This directly proves that its intelligent release characteristics can more accurately match crop needs, thereby achieving efficient nutrient utilization and yield improvement, constituting a substantial technological advancement. The experimental group produced more seedlings and grew better.
Claims
1. A method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis, characterized in that, The preparation method is as follows:
1. The corn syrup is diluted using a high-speed shear homogenizer to obtain a homogenized liquid. The homogenized liquid is then subjected to ultrasonic pretreatment, followed by the addition of a bio-flocculator. After the reaction, coarse material is obtained.
2. After adding enzyme A to the crude material, stock solution 1 is obtained. Stock solution 1 is pumped into the first membrane reactor. After circulating membrane separation, filtrate 1 and concentrate 1 are obtained respectively. The circulating membrane separation is as follows: after stock solution 1 is pumped into the first membrane reactor, it is filtered to obtain filtrate and concentrate. Then, the filtrate and concentrate are re-entered into the first membrane reactor for circulation. The circulation reaction is carried out for 0.5~4 hours to complete one round of circulating membrane separation, obtaining filtrate 1 and concentrate. Then, the concentrate is mixed with new stock solution 1 for a new round of circulating membrane separation. After 3~15 rounds of circulating membrane separation, concentrate 1 is obtained.
3. Add enzyme B to filtrate 1 to obtain stock solution 2, then pump it into the second membrane reactor. After circulating membrane separation, filtrate 2 and concentrate 2 are obtained respectively. The circulating membrane separation is as follows: after stock solution 2 enters the second membrane reactor, it is filtered to obtain filtrate and concentrate. Then the filtrate and concentrate are re-entered into the second membrane reactor for circulation. After 2-6 hours of circulation reaction, one round of circulating membrane separation is completed, obtaining filtrate 2 and concentrate. The concentrate is mixed with new stock solution 2 for a new round of circulating membrane separation. After 5-20 rounds of circulating membrane separation, concentrate 2 is obtained. IV. Add biochar and compound materials to concentrated liquid 1, stir evenly, dry, extrude and granulate to obtain solid fertilizer; 5. Add concentrated liquid 2 to the compound materials to obtain liquid fertilizer.
2. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, In step one, the ultrasonic frequency is 20-40 kHz, the power density is 0.3-0.8 W / mL, and the action time is 2-5 min.
3. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, In step one, the bio-flocculator is one or a mixture of chitosan and polyglutamic acid, with an addition amount of 1~10g / L and a reaction time of 10~60min.
4. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, In step two, enzyme A is an acidic protease, and the amount added is 0.5~6g / L.
5. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, The molecular weight cutoff of the membrane in the first membrane reactor described in step two is 5~20kDa.
6. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, Step 3 Enzyme B is a mixture of phytase, pectinase, amylase and acid phosphatase in a mass ratio of 1:1:1:1, and the amount added is 0.5~7g / L.
7. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, The molecular weight cutoff of the membrane in the second membrane reactor described in step three is 500 Da.
8. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, A method for preparing thermo-responsive solid fertilizer using concentrated liquid 1: Biochar and compound materials are added to concentrated liquid 1 and stirred evenly to form a core material mixture; then, fluidized bed coating technology is used for coating, and the coated particles are dried to a moisture content of less than 30% to obtain thermo-responsive solid fertilizer; wherein the particle size of biochar is 20-100 mesh, and the mass ratio of biochar to concentrated liquid 1 is (0.05-0.2):1, and the coating material is poly(N-isopropylacrylamide) hydrogel.
9. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 1, characterized in that, The method for preparing temperature-sensitive and pH-sensitive dual-response liquid fertilizer using concentrated solution 2 is as follows: Concentrated solution 2 is added to the compound material, and then N-isopropylacrylamide monomer and acrylic acid monomer are added to obtain a mixed solution; crosslinking agent N,N'-methylenebisacrylamide is added to the mixed solution at an amount of 0.5%-2.0% of the total monomer mass; then ammonium persulfate is added as an initiator at an amount of 0.5%-1.5% of the total monomer mass to obtain a mixed system; the mixed system is then placed in a closed reactor and reacted under an inert atmosphere at a temperature controlled at 60-70℃ with continuous stirring for 2-6 hours to obtain the temperature-sensitive and pH-sensitive dual-response liquid fertilizer.
10. The method for preparing corn steep liquor fertilizer based on cyclic membrane separation and enhanced enzymatic hydrolysis according to claim 9, characterized in that, Based on the volume of concentrated solution 2, the amount of N-isopropylacrylamide monomer added is 5%-10% w / v, and the amount of acrylic acid monomer added is 1%-3% w / v.