High nutrient adsorptive full-biomass planting foam and preparation method thereof

Abstract

The present application relates to soilless culture technical field, especially to a kind of high nutrient adsorption full biomass planting foam and its preparation method, raw material component includes: plant fiber 5-7 parts by weight, chitosan 2-3 parts by weight, crosslinking agent 0.5-4 parts by weight, foaming agent 0.5-2 parts by weight.In the process of the present application, freeze-thaw setting-medium thawing process is added, which can significantly improve the uniformity of foam pores, and the three-dimensional structure built by wood fiber can effectively prevent the foam from collapsing during the forming process under low chitosan concentration, thereby reducing resource waste.Meanwhile, as the main matrix, cellulose and chitosan contain abundant hydroxyl and amino groups, and the foam has good hydrophilicity, which greatly enhances the adsorption capacity of water and nutrients in the nutrient solution, and under the action of a certain amount of crosslinking agent, chitosan forms a gel structure component, which cooperates with the foam fiber structure to improve the water and nutrient storage capacity of the foam.

Description

Technical Field

[0001] This invention relates to the field of soilless cultivation technology, specifically to a high-nutrient-adsorption biomass planting foam and its preparation method. Background Technology

[0002] With the increasing scarcity of land resources in my country, the diversification of horticultural crop cultivation methods, and the urgency of environmental protection, traditional soil cultivation can hardly meet the needs of modern agricultural production. There is an urgent need for alternative methods to cultivate plants. In recent years, planting foam has emerged as a new type of molded cultivation substrate, which has the advantages of controllable water-air ratio, light weight, beautiful appearance, strong plasticity, and simple and convenient use.

[0003] Currently, molded horticultural planting foams mainly consist of rock wool planting blocks and synthetic resin polyurethane foam. Rock wool, a commonly used soilless cultivation substrate both domestically and internationally, suffers from high energy consumption during production, large volume leading to high transportation costs, short lifespan, difficulty in degradation, and high recycling costs. Synthetic resin planting foams, on the other hand, are inexpensive. For example, patent CN112341600A discloses a soilless cultivation sponge and its preparation method. This method utilizes polyurethane resin foam to produce a lightweight planting sponge with a high open-cell ratio; however, the raw materials used are all petroleum-based, exhibiting drawbacks such as non-renewability, difficulty in biodegradation, and poor environmental performance. Patent CN102504169A discloses a polyurethane foam material for soilless cultivation and its preparation method, in which 30-50 parts by weight of biodegradable liquefied starch polyol is used to improve the biodegradability of the polyurethane foam, but it still primarily uses petroleum-based raw materials.

[0004] Patent CN108148418A discloses a foam material made from waste shellac residue for hydroponics and its preparation method. The foam has good mechanical properties and biodegradability, but the source of raw materials is limited and the preparation process is relatively complex. Patent CN202410598098 discloses a production process for wood fiber cultivation substrate blocks. The substrate blocks are inexpensive and easily degradable. However, this method uses a hot pressing process, which results in uncontrollable pore structure and poor plasticity.

[0005] This invention addresses the problems of existing planting sponges, such as non-renewability, poor biodegradability, difficulty in recycling, and poor hydrophilicity. It proposes a method for preparing all-biomass foam for soilless cultivation. By adding a freeze-thaw setting-medium thawing process, the small pore size and pore uniformity of the foam are improved. The prepared all-biomass foam has the advantages of good hydrophilicity, nutrient adsorption, good degradability, and recyclability, making it suitable for plant seedling cultivation. Furthermore, the foam prepared by this method can be formed at a lower material ratio, effectively reducing the cost of raw materials and improving resource utilization. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a highly nutrient-absorbing biomass planting foam and its preparation method, solving the problems of existing planting sponges being non-renewable, difficult to degrade, difficult to recycle, and having poor hydrophilicity.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a high nutrient adsorption biomass planting foam, the raw material components of which include: 5-7 parts by weight of plant fiber, 2-3 parts by weight of chitosan, 0-4 parts by weight of crosslinking agent, and 0.5-2 parts by weight of foaming agent.

[0008] Preferably, the plant fiber raw material is obtained by steam explosion or kneading mechanical separation method, and the fiber particle size is less than 60 mesh. The source of plant fiber raw material can be various types of wood, bamboo, sugarcane bagasse and other agricultural and forestry residues with rich fiber content.

[0009] Preferably, the chitosan has a molecular weight of 30,000 and a degree of acetylation of ≤85%.

[0010] Preferably, the crosslinking agent is one of the polybasic organic acids such as citric acid, tartaric acid, malic acid, and ascorbic acid, with a mass percentage concentration between 0% and 4%.

[0011] Preferably, the foaming agent is one of the polyoxyethylene nonionic surfactants such as Triton or Tween, with a mass percentage concentration between 0.5% and 2%.

[0012] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0013] (1) Weigh out chitosan according to the formula and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent according to the formula and react at 40℃ for 1 hour.

[0014] (2) Add the formulated plant fiber to the solution, mix evenly with a stirrer, add foaming agent, stir and foam at a rate of 300-1000r / min for 2-3min to obtain foaming liquid, and then quickly freeze the foaming liquid;

[0015] (3) Thaw the frozen foaming liquid after shaping, soak it in the thawing medium to shape it, and wash it with distilled water until neutral.

[0016] (4) After soaking in plant growth regulators as needed, dry the foam and cool it to room temperature. After demolding, obtain the whole biomass planting foam material.

[0017] Preferably, plant growth regulators need to be formulated according to the needs of different crop cultivation. The plant growth regulators are mainly functional substances that regulate plant growth and development.

[0018] Plant growth regulators are one or more of the following: plant growth hormones such as indoleacetic acid, indolebutyric acid, and paclobutrazol, or functional substances such as humic acid and fulvic acid.

[0019] Preferably, cryo-setting can be achieved by rapid freezing with liquid nitrogen, or by freezing in an environment of -18℃ to -24℃ for 12-24 hours. The thawing solution can be sodium hydroxide, ethanol, or distilled water.

[0020] Preferably, the foam is dried in an oven at 60°C-80°C or by freeze drying.

[0021] Preferably, the fibers can be reused through a specific process. After washing with acetic acid solution, they can be washed with water, and the resulting fibers can be recycled using the preparation method described above.

[0022] Beneficial effects

[0023] This invention provides a highly nutrient-adsorbent biomass planting foam and its preparation method. Compared with the prior art, it has the following advantages:

[0024] 1. The high nutrient adsorption biomass planting foam prepared by this invention incorporates a freeze-thaw setting-medium thawing process, which can significantly improve the uniformity of foam pores. The three-dimensional structure built with wood fibers can effectively prevent the foam from collapsing during the molding process at lower chitosan concentrations, thereby reducing resource waste.

[0025] 2. The high nutrient adsorption biomass planting foam prepared by this invention contains abundant hydroxyl and amino groups in cellulose and chitosan as the main matrix. The foam has good hydrophilicity and, together with the uniform pore structure of the foam, greatly enhances the adsorption capacity of water and nutrients in the nutrient solution.

[0026] 3. The high nutrient adsorption biomass planting foam prepared by this invention has chitosan forming a gel structure component under the action of a certain amount of cross-linking agent. This component works synergistically with the foam fiber structure to improve the foam's water and nutrient storage capacity while meeting the plant roots' need for ventilation.

[0027] 4. The high nutrient adsorption biomass planting foam prepared by this invention is made entirely of biomass, which is biodegradable. Through the process described in this invention, it can be recycled and reused, which has great environmental advantages. Attached Figure Description

[0028] Figure 1 The flowchart shown is for the preparation of highly nutrient-adsorbent biomass planting foam.

[0029] Figure 2 The image shows an application diagram of highly nutrient-absorbing biomass planting foam. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments and comparative examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 0 parts by weight of crosslinking agent, and 1 part by weight of Triton foaming agent.

[0033] Plant fiber raw materials are obtained by steam explosion or kneading mechanical separation methods. The fiber particle size is less than 60 mesh. The sources of plant fiber raw materials can be various types of wood, bamboo, sugarcane bagasse and other agricultural and forestry residues with rich fiber content.

[0034] The chitosan has a molecular weight of 30,000 and a degree of acetylation of ≤85%.

[0035] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0036] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add 5g of eucalyptus fiber to the solution and stir with a stirrer until well mixed.

[0037] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ refrigerator for 12h.

[0038] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0039] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0040] Example 2

[0041] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 7 parts by weight of eucalyptus fiber, 2 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0042] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0043] (1) Weigh 2g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 7g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0044] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0045] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0046] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0047] Example 3

[0048] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 7 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 0.5 parts by weight of citric acid as a crosslinking agent, and 0.5 parts by weight of Triton as a foaming agent.

[0049] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0050] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 7g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0051] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0052] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0053] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0054] Example 4

[0055] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 6 parts by weight of sugarcane bagasse fiber, 3 parts by weight of chitosan, 1 part by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0056] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0057] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 6g of sugarcane bagasse fiber to the solution and stir with a stirrer to mix evenly.

[0058] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0059] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0060] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0061] Example 5

[0062] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of recycled wood fiber, 3 parts by weight of chitosan, 1 part by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0063] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0064] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of recycled wood fiber to the solution and stir with a stirrer to mix evenly.

[0065] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0066] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0067] (4) Dry the foam in an oven at 60°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0068] The foam recycling process described in Example 5 is as follows: after soaking in acetic acid solution, the foam is washed with clean water to obtain recycled fibers.

[0069] Comparative Example 1

[0070] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 8 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0071] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0072] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 8g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0073] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0074] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0075] (4) After soaking in plant growth regulator, the foam is dried in an oven at 60°C. After drying, it is cooled to room temperature and demolded to obtain whole biomass planting foam.

[0076] Comparative Example 2

[0077] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 4 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0078] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0079] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 4g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0080] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0081] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0082] (4) After soaking in plant growth regulator, the foam is dried in an oven at 60°C. After drying, it is cooled to room temperature and demolded to obtain whole biomass planting foam.

[0083] Comparative Example 3

[0084] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0085] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0086] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0087] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0088] (3) Thaw the frozen foaming liquid after shaping;

[0089] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0090] Comparative Example 4

[0091] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0092] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0093] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0094] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid;

[0095] (3) After soaking in plant growth regulator, the foam is dried in an 80°C oven. After drying, it is cooled to room temperature and demolded to obtain whole biomass planting foam.

[0096] Comparative Example 5

[0097] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 1 part by weight of chitosan, 4 parts by weight of citric acid as crosslinking agent, and 1 part by weight of Triton as foaming agent.

[0098] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0099] (1) Weigh 1g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0100] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0101] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0102] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0103] Comparative Example 6

[0104] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 4 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0105] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0106] (1) Weigh 4g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer until evenly mixed.

[0107] (2) Add foaming agent and stir at 300r / min for 2-3min, then freeze the foaming liquid in a -20℃ freezer for 12h;

[0108] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0109] (4) After soaking in plant growth regulator, the foam is dried in an 80°C oven. After drying, it is cooled to room temperature and demolded to obtain whole biomass planting foam.

[0110] Comparative Example 7

[0111] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 5 parts by weight of citric acid as a crosslinking agent, and 1 part by weight of Triton as a foaming agent.

[0112] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0113] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0114] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0115] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0116] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0117] Comparative Example 8

[0118] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 0.3 parts by weight of Triton as a foaming agent.

[0119] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0120] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0121] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0122] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0123] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0124] Comparative Example 9

[0125] A highly nutrient-absorbing biomass planting foam, the raw material components of which include: 5 parts by weight of eucalyptus fiber, 3 parts by weight of chitosan, 4 parts by weight of citric acid as a crosslinking agent, and 3 parts by weight of Triton as a foaming agent.

[0126] A method for preparing a highly nutrient-adsorbent biomass planting foam, the method comprising the following steps:

[0127] (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of eucalyptus fiber to the solution and stir with a stirrer to mix evenly.

[0128] (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ freezer for 12h.

[0129] (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral;

[0130] (4) Dry the foam in an oven at 80°C, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam.

[0131] Comparing the all-biomass planting foams prepared in Example 2 and Comparative Example 1, the addition of a freeze-thaw process during foam preparation can significantly improve the uniformity of the foam's pore structure.

[0132] The performance of the whole biomass crops prepared in Examples 1-4 and Comparative Examples 2, and Examples 3 and Comparative Examples 5-8 was tested using the following methods:

[0133] (1) Foam porosity test

[0134] Using the solution displacement method, a foam (25×25×25mm) was immersed in a fixed volume (V1) of anhydrous ethanol solution, and the total volume of foam and anhydrous ethanol (V2) was recorded. After 5 minutes, the foam was removed, and the volume of anhydrous ethanol at this time was recorded as V3. The porosity was calculated using the following formula.

[0135] (2) Foam apparent density test

[0136] Use vernier calipers to measure the length, width, and height of the foam, calculate its volume V, and weigh it to determine its mass m. Also measure the apparent density of the foam.

[0137] (3) Water absorption rate test

[0138] Weigh the foam (25×25×25mm) and record the mass as M1. Then immerse it in a beaker containing 100mL of distilled water. After 24 hours, remove it, place it on a filter sieve, let it stand for 1 minute, and weigh it again. Record the mass as M2. The water absorption rate is...

[0139] (4) The compressive strength of the foam was tested by a universal tensile testing machine, and the test was conducted in accordance with GB / T1041-92. The compression rate was 2 mm / min.

[0140] The material content and preparation details of the above examples are shown in Table 1.

[0141]

[0142] The performance test results of the embodiments and comparative examples are shown in the table below:

[0143]

[0144] The test results show that the foam prepared using this method exhibits nutrient adsorption values ​​greater than 0.2 ms / cm*g, indicating that the foam prepared using this freeze-thaw method has good adsorption performance. Furthermore, the recycled fibers, containing the chitosan-citric acid gel that was not separated during the recycling process, have an even higher nutrient adsorption capacity. Observations in Examples 1 and 2 reveal that while the increase in citric acid occupies adsorption sites on the one hand, reducing electrostatic interaction, it also promotes pore formation, thereby increasing capillary adsorption. Observations in Examples 1 and 3 show that the foam without freeze-thaw treatment has a decreased porosity, significantly reducing capillary adsorption and thus lowering its adsorption performance.

[0145] To further illustrate the superiority of this method, the nutrient-adsorbing foams prepared in Example 1 and Comparative Example 1 were compared. The results showed that excessively high fiber content increased the overall density of the foam, thus hindering the adsorption of water and nutrients. Comparative Example 2 showed that reducing the fiber content caused the foam to collapse during the foaming process. Comparative Example 3 clearly showed that the freeze-thaw method formed a more uniform pore structure. Therefore, adding a freezing process during foam preparation can significantly improve the uniformity of the foam's pore structure. Comparative Examples 4 and 7 showed that adding a medium melting process can prevent the foam from dissolving due to excessive acidity. Comparative Examples 5 and 6 showed that when the chitosan content was low, the foam foamed unevenly during the molding process due to the low viscosity of the solution and difficulty in the medium entering during melting. Simultaneously, when the chitosan content was high, the chitosan was difficult to dissolve and mold. Comparative Examples 8 and 9 showed that the Triton content was related to the foaming height of the foaming liquid. When the foaming height was too low, the thawing medium could not easily enter the foam, causing the foam to collapse. When the foaming rate is too high, it becomes difficult for the medium to enter the foam and form uniform pore sizes.

[0146] Example 1 was applied to a hydroponic experiment of Chinese cabbage. The results showed that the all-biomass planting foam prepared by the method described in the patent can be applied to the nutrient solution cultivation of horticultural crops and has a good cultivation effect.

[0147] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

Claims

1. A method for preparing a highly nutrient-adsorbent biomass planting foam, characterized in that: The raw material components of all-biomass planting foam include: 5g recycled wood fiber, 3g chitosan, 1g citric acid as crosslinking agent, and 1g Triton as foaming agent; The method for preparing foam for all-biomass planting includes the following steps: (1) Weigh 3g of chitosan and dissolve it in 100 parts of 1% w / v acetic acid solution. Add crosslinking agent and react at 40℃ for 1h. Add 5g of recycled wood fiber to the solution and stir with a stirrer to mix evenly. (2) Add foaming agent and stir at 300r / min for 2-3min to obtain foaming liquid. Then freeze the foaming liquid in a -20℃ refrigerator for 12h. (3) Thaw the frozen foaming liquid after shaping, soak it in 2% sodium hydroxide for shaping, and wash it with distilled water until neutral; (4) Dry the foam in a 60°C oven, and after drying, cool it to room temperature to demold it to obtain whole biomass planting foam; The recycled fiber is made by soaking whole biomass planted foam in acetic acid solution and then washing it with clean water.

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