Cadmium-resistant slow-release block for crop planting as well as preparation method and application of cadmium-resistant slow-release block
The cadmium-inhibiting slow-release block formed by the interpenetrating cross-linking of organic and inorganic materials solves the problems of short cadmium pollution remediation cycle, high cost and frequent spraying in the existing technology, and achieves long-term, economical and environmentally friendly cadmium inhibition effect, reducing the accumulation of cadmium in plants and ensuring crop growth.
Patent Information
- Application Number
- CN202511947651.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies for remediating cadmium pollution in soil/culture substrates suffer from problems such as short remediation cycles, high costs, and harsh conditions for soil degradation and implementation. Furthermore, existing inhibitors require frequent spraying, which limits their widespread adoption.
The cadmium-inhibiting slow-release block, formed by interpenetrating cross-linking of organic and inorganic materials, inhibits the absorption of cadmium by crops by slowly releasing cadmium inhibitors during crop growth. The cadmium-inhibiting slow-release block is formed by cross-linking organic materials such as linear corn starch and branched corn starch with inorganic materials such as ferrous salts to form a backbone, and then coating it with a soluble cadmium inhibitor to form an interpenetrating cross-linked backbone.
It achieves a long-lasting, economical, and environmentally friendly cadmium inhibition effect, reducing the cadmium accumulation in plants by 67%-88%, without affecting crop growth or the soil environment, and has a service life of 2-5 years.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of agricultural vegetable planting, and specifically discloses a cadmium-inhibiting slow-release block for vegetable planting, its preparation method and application. Background Technology
[0002] Cd in soil / culture substrates is highly toxic: for crops, a certain amount of Cd absorption can lead to adverse conditions such as yellowing leaves, stunted growth, and slow growth (Szumigalski RA, Acker VCR. Nitrogen Yield and Land Use Efficiency in Annual Sole Crops and Intercrops[J]. Agronomy Journal,2006,98(4):1030-1040.); for humans, Cd enters and accumulates in the human body along the food chain, disrupting normal physiological functions and posing a strong risk of teratogenicity and carcinogenicity.
[0003] Existing Cd contamination remediation technologies for soil / culture media mainly include: soil / culture media improvement, phytoremediation, screening for low-accumulation plants, and agronomic measures. Soil / culture media improvement primarily involves applying passivating agents and soil conditioners to the soil / culture media to reduce Cd migration, thereby blocking Cd absorption by plants. Currently, commonly used amendments are biochar and lime. Compared to other remediation technologies, this technology has advantages such as a short remediation cycle and no impact on production; however, it also has disadvantages such as a short remediation period (usually requiring annual remediation), soil / culture media deterioration, and high remediation costs.
[0004] Phytoremediation technology mainly includes two aspects: phytostatic fixation and phytoextraction. Phytostatic fixation utilizes the redox, accumulation, chelation, or stabilization effects of plant roots to reduce the migration capacity and bioavailability of Cd in the soil. Phytoextraction refers to the absorption and accumulation of Cd in contaminated soil by plants, which are then harvested together with the plant to reduce the Cd content in the soil. Phytoremediation technology is mainly used to remediate contaminated soil, and it has advantages such as low economic cost and minimal soil damage; however, this technology still has problems such as long remediation cycles, the inability to use the soil for production during the remediation process, and the final treatment of highly accumulated plants.
[0005] Available agronomic measures typically include water and fertilizer management, screening for low-accumulation varieties, and application of control agents. Water and fertilizer management refers to optimizing field water and fertilizer management according to the different growth stages of crops, thereby reducing the absorption and accumulation of heavy metals by crops. This technology is highly economical, but its implementation conditions are demanding, and the remediation goals are not easily achieved. Screening for low-accumulation varieties is environmentally friendly and low-cost, but its crop-specific limitations make it difficult to promote without external economic assistance. Common control agents are foliar control agents, which inhibit the plant's absorption and translocation of Cd by spraying the crop leaves, thus achieving the remediation goal. While foliar control agents can effectively inhibit crop absorption of Cd, they require frequent application, and their high price also limits the widespread adoption of this technology.
[0006] Therefore, a new inhibitor that is long-acting, easy to implement, and low-cost can effectively reduce the hindering effect of Cd pollution on my country's agricultural development. Summary of the Invention
[0007] The purpose of this invention is to provide a cadmium-inhibiting slow-release block for crop, especially vegetable, cultivation, its preparation method and application, particularly a green, economical, slow-release and long-lasting slow-release block synthesis technology that can be used to inhibit the absorption of Cd from soil / culture substrate by vegetables.
[0008] To achieve the above objectives, the present invention provides the following technical solution.
[0009] This invention provides a cadmium-inhibiting slow-release block for crop cultivation. The main body of the cadmium-inhibiting slow-release block is made of an interpenetrating cross-linked framework of organic and inorganic materials, crosslinked clay minerals, and coated with a soluble cadmium inhibitor. It is used to inhibit the absorption of cadmium from the soil / culture substrate during crop growth. Preferably, the crop is a vegetable.
[0010] The organic material in the cadmium-blocking slow-release block described above is selected from two or more of the following: linear corn starch, branched corn starch, alginic acid, alginate, maltodextrin, konjac flour, gelatin, xanthan gum, tamarind gum, carboxymethyl cellulose, and hydroxypropyl cellulose.
[0011] The inorganic material in the cadmium-inhibiting slow-release block described above is selected from environmentally friendly divalent and trivalent ferric salts, preferably including two or more of ferrous sulfate, ferric sulfate, ferrous nitrate, ferric nitrate, ferrous chloride, and ferric chloride.
[0012] As described above, the clay mineral in the cadmium-inhibiting slow-release block is selected from one or more of sepiolite powder, attapulgite, bentonite, diatomite, and kaolin. Preferably, the bentonite is calcium-based bentonite. Preferably, the kaolin is washed or calcined. Preferably, the fineness of the sepiolite powder is 150 mesh to 200 mesh.
[0013] The cadmium-inhibiting slow-release block described above uses a cadmium inhibitor selected from one or more of calcium hydroxide, calcium phosphate, calcium dihydrogen phosphate, and calcium citrate.
[0014] As described above, the cadmium-inhibiting slow-release block comprises an interpenetrating cross-linked framework of organic and inorganic materials. The mixture consists of a solid-phase mixture of 4%-8% organic materials and 4%-8% inorganic materials by mass, based on the total mass of the cadmium-inhibiting slow-release block material. This mixture is then activated with a 10%-30% hydrogen peroxide solution. Preferably, the concentration of the hydrogen peroxide solution is 10%. Under the activation of hydrogen peroxide, the organic materials undergo a grafting reaction or a polymerization reaction with metal ions to form an organic molecular network. Under the activation of hydrogen peroxide, the inorganic materials polymerize into an amorphous metal molecular network due to charge changes. The two networks interpenetrate to form an interpenetrating cross-linked framework.
[0015] The cadmium-inhibiting slow-release block described above is made by mixing 20%-40% by mass of the clay mineral and 20%-60% by mass of the cadmium inhibitor solid phase, based on the total mass of the cadmium-inhibiting slow-release block material, and then rapidly mixing it with the interpenetrating cross-linked skeleton. Preferably, it is cured for 24-36 hours to form a solid slow-release block. Preferably, the compressive strength of the solid slow-release block is 3.66 MPa-8.51 MPa.
[0016] This invention also provides a method for preparing the cadmium-inhibiting slow-release block as described above. The method uses raw materials comprising, by weight, 2-4% alginic acid, 2-4% hydroxypropyl cellulose, 2-4% ferric sulfate, 0.5-2.5% ferrous sulfate, 10-30% calcium phosphate, 20-40% kaolin, 10-30% calcium hydroxide, and 10-30% hydrogen peroxide solution. The alginic acid, hydroxypropyl cellulose, ferric sulfate, ferrous sulfate, and hydrogen peroxide solution are mixed and activated, and then rapidly mixed with the calcium phosphate, calcium hydroxide, and kaolin. The mixture is stirred evenly and then poured into a mold. After curing (e.g., 12-36 hours, specifically 20-28 hours, more specifically 24 hours), the cadmium-inhibiting slow-release block is formed. Preferably, the kaolin is washed kaolin. Preferably, the concentration of the hydrogen peroxide solution is 10%. Preferably, the raw materials used in the method are, by mass fraction, 3% alginic acid, 3% hydroxypropyl cellulose, 3% ferric sulfate, 1.5% ferrous sulfate, 20% calcium phosphate, 30% kaolin, 20% calcium hydroxide, and 19.5% hydrogen peroxide solution.
[0017] The present invention also provides a cadmium-inhibiting slow-release block obtained by the preparation method described above.
[0018] The present invention also provides the application of the cadmium-inhibiting slow-release block as described above, which is used in crop cultivation and is applicable throughout the entire crop growth cycle; preferably, the crop is a vegetable, preferably the application dosage is 800 kg / hm2-1600 kg / hm2; preferably, the service life is 2-5 years; preferably, the application method includes putting it into irrigation canals, putting it into drip irrigation tanks, pre-burying / burying it at the roots of plants, installing it in a net box at the sprinkler inlet, or suspending it in a net bag at the roots of plants; preferably, the cadmium-inhibiting effect is to reduce the cadmium accumulation in plants by 67%-88%.
[0019] The invention of the cadmium-inhibiting slow-release block achieves its intended effect through the following measures:
[0020] (1) Place the cadmium-inhibiting slow-release blocks in blocks (2×2×2cm) 3 -4×4×2cm 3 In the form of 800 kg / hm 2 -1600kg / hm 2 The dosage is applied directly to the surface of the soil / culture substrate. The active ingredients of the slow-release block slowly enter the soil / culture substrate with the irrigation water to achieve the purpose of cadmium inhibition. The lifespan of the slow-release block in this way is 3-5 years.
[0021] (2) The cadmium-inhibiting slow-release blocks are put into the water storage tank. The slow-release blocks release cadmium-inhibiting components in the water at a release rate of 0.5 mol / t / d-3.2 mol / t / d. The cadmium-inhibiting components enter the soil / culture substrate with the irrigation water through flood irrigation, sprinkler irrigation, drip irrigation and other methods to achieve the purpose of inhibiting the absorption of cadmium by vegetables. The lifespan of the slow-release blocks in this way is 1-2 years.
[0022] (3) Slow-release blocks can also be implemented in various ways, such as pre-burying them in the soil / culture medium, hanging them at the irrigation outlet, or covering them on the soil / culture medium around the roots of vegetables.
[0023] The cadmium-inhibiting slow-release block of the present invention has the characteristics of simple application, long-lasting cadmium inhibition, strong resistance to environmental pH, green materials, no damage to plants and no reduction in yield. At the same time, it has excellent cadmium inhibition effect and can reduce the cadmium accumulation in plants by 67%-88%. Attached Figure Description
[0024] Figure 1 Cadmium-inhibiting slow-release block (inorganic network only).
[0025] Figure 2 Cadmium-inhibiting slow-release block (organic network only).
[0026] Figure 3 Cadmium-inhibiting slow-release block (organic-inorganic interpenetrating network).
[0027] Figure 4 shows the crop planting verification of cadmium-inhibiting slow-release blocks. In Figure 4, A represents the early stage of crop growth, and B represents the middle stage of crop growth.
[0028] Figure 5. Images of the control group crops at the corresponding planting stages. In Figure 5, A represents the early stage of crop growth, and B represents the middle stage of crop growth. Detailed Implementation
[0029] The present invention will be further illustrated by way of example below, which includes but does not limit the scope of protection of the present invention.
[0030] Comparative Example 1: Cadmium-inhibiting slow-release block (inorganic network only)
[0031] The mixture consists of 1 part ferric sulfate, 0.5 parts ferrous sulfate, 25 parts calcium phosphate, 30 parts kaolin (washed), 20 parts calcium hydroxide, and 23.5 parts hydrogen peroxide solution (prepared using a 10% hydrogen peroxide solution to achieve a 2.12% hydrogen peroxide solution; 23.5 parts of this solution are added, with a final actual consumption of 0.5 parts). After the ferric sulfate and ferrous sulfate are activated by mixing with the hydrogen peroxide solution, they are quickly mixed with the calcium phosphate, calcium hydroxide, and kaolin. The mixture is stirred thoroughly and then poured into a mold. After curing for 24 hours, a shape is formed as shown in the image. Figure 1 Cadmium-inhibiting slow-release blocks.
[0032] Because the finished product lacks organic materials, it cannot form an organic-inorganic interpenetrating cross-linked framework. The resulting cadmium-blocking slow-release block has a loose structure, which collapses when it comes into contact with water, thus losing its slow-release ability.
[0033] Comparative Example 2: Cadmium-inhibiting slow-release block (organic network only)
[0034] The mixture consists of 3 parts by weight of alginic acid, 3 parts of hydroxypropyl cellulose, 21 parts of calcium phosphate, 30 parts of kaolin (washed), 20 parts of calcium hydroxide, and 23 parts of water. The alginic acid, hydroxypropyl cellulose, and water are mixed evenly, then quickly mixed with the calcium phosphate, calcium hydroxide, and kaolin. After thorough mixing, the mixture is poured into a mold and cured for 24 hours to form a shape resembling... Figure 2 The cadmium-inhibiting slow-release block. In this control example, the organic component is activated by metal ions provided by the inorganic component.
[0035] Because the finished product lacks inorganic materials, it cannot form an organic-inorganic interpenetrating cross-linked framework. As a result, the cadmium-blocking slow-release block structure is soft, easily sticks together when exposed to water, and has unstable slow-release performance.
[0036] Experimental Example 1: Cadmium-Resistant Slow-Release Block (Organic-Inorganic Interpenetrating Network)
[0037] The mixture consists of 3 parts by mass of alginic acid, 3 parts of hydroxypropyl cellulose, 3 parts of ferric sulfate, 1.5 parts of ferrous sulfate, 20 parts of calcium phosphate, 30 parts of kaolin (washed), 20 parts of calcium hydroxide, and 19.5 parts of hydrogen peroxide solution (containing 0.8 parts of hydrogen peroxide). After the alginic acid, hydroxypropyl cellulose, ferric sulfate, ferrous sulfate, and hydrogen peroxide solution are mixed and activated, they are quickly mixed with calcium phosphate, calcium hydroxide, and kaolin. The mixture is stirred thoroughly and then poured into a mold. After curing for 24 hours, a mixture is formed as shown in the image. Figure 3 Cadmium-inhibiting slow-release blocks.
[0038] The finished product has a sustained-release coating structure formed by an organic-inorganic interpenetrating cross-linked framework. The compressive strength of the material is between 3.66 MPa and 8.51 MPa, the dynamic (laboratory packed column, at a flow rate of 30 ml / min) release rate is between 0.5 mol / t / d and 2.2 mol / t / d, and the static release rate (laboratory material to water mass ratio of 1:5) is between 0.2 mol / t / d and 1.3 mol / t / d.
[0039] Experimental Example: Verification of Cadmium-Inhibited Slow-Release Block Crop Cultivation
[0040] From July to October 2025, the cadmium-inhibiting effect of the cadmium-inhibiting slow-release blocks prepared in Example 1 was verified in a high-cadmium farmland. The test area was 1333 m². 2 666.6m 2 Apply cadmium-inhibiting slow-release blocks at a dosage of 1500 kg / hm². 2 (See Figure 4); Additional 666.6m 2 Basic field management was performed only, serving as a control crop for the slow-release cadmium-inhibiting material (see Figure 5). The test crops were seven different varieties and breeding units of cowpeas, and the verification results are shown in Table 1.
[0041] Table 1. Cadmium inhibition results of the cadmium-inhibiting slow-release block prepared in Example 1
[0042]
[0043] Compared to control crops, crops treated with slow-release cadmium-inhibiting materials showed an average reduction of 29% in cadmium content, with the cadmium-inhibiting effect being better for bean varieties that were more prone to cadmium accumulation.
Claims
1. A cadmium-inhibiting slow-release block for crop cultivation, characterized in that, The main body of the cadmium-inhibiting slow-release block is made of an interpenetrating cross-linked framework of organic and inorganic materials, crosslinked clay minerals, and coated with a soluble cadmium inhibitor. Preferably, the crop is a vegetable.
2. The cadmium-inhibiting slow-release block according to claim 1, characterized in that, The organic material is selected from two or more of the following: linear corn starch, branched corn starch, alginic acid, alginate, maltodextrin, konjac flour, gelatin, xanthan gum, tamarind gum, carboxymethyl cellulose, and hydroxypropyl cellulose.
3. The cadmium-inhibiting slow-release block according to claim 1, characterized in that, The inorganic material is selected from environmentally friendly divalent and trivalent ferric salts, preferably including two or more of ferrous sulfate, ferric sulfate, ferrous nitrate, ferric nitrate, ferrous chloride, and ferric chloride.
4. The cadmium-inhibiting slow-release block according to claim 1, characterized in that, The clay mineral is selected from one or more of sepiolite powder, attapulgite, bentonite, diatomite, and kaolin. Preferably, the bentonite is calcium-based bentonite. Preferably, the kaolin is washed or calcined. Preferably, the fineness of the sepiolite powder is 150 mesh to 200 mesh.
5. The cadmium-inhibiting slow-release block according to claim 1, characterized in that, The cadmium inhibitor is selected from one or more of calcium hydroxide, calcium phosphate, calcium dihydrogen phosphate, and calcium citrate.
6. The cadmium-inhibiting slow-release block according to any one of claims 1-5, characterized in that, The aforementioned interpenetrating cross-linked framework of organic and inorganic materials is prepared by mixing organic materials with a mass fraction of 4%-8% and inorganic materials with a mass fraction of 4%-8% in a solid phase, based on the total mass of the cadmium-inhibiting slow-release block material, and then activating it with a mass fraction of 10%-30% hydrogen peroxide aqueous solution. Preferably, the concentration of the hydrogen peroxide solution is 10%, and the organic material undergoes a grafting reaction or a polymerization reaction with metal ions to form an organic molecular network under the activation of hydrogen peroxide; the inorganic material polymerizes into an amorphous metal molecular network due to charge change under the activation of hydrogen peroxide; the two networks interpenetrate to form an interpenetrating cross-linked framework.
7. The cadmium-inhibiting slow-release block according to any one of claims 1-6, characterized in that, Based on the total mass of the cadmium-inhibiting slow-release block material, it is prepared by mixing 20%-40% by mass of the clay mineral and 20%-60% by mass of the cadmium-inhibiting agent in a solid phase, and then rapidly mixing them with the interpenetrating cross-linked framework. Preferably, the solid slow-release block is formed by curing for 24-36 hours. Preferably, the compressive strength of the solid slow-release block is 3.66MPa-8.51MPa.
8. The method for preparing the cadmium-inhibiting slow-release block according to any one of claims 1-7, characterized in that, The method uses raw materials comprising, by mass fraction (based on total mass of cadmium-inhibiting slow-release block material): 2-4% alginic acid, 2-4% hydroxypropyl cellulose, 2-4% ferric sulfate, 0.5-2.5% ferrous sulfate, 10-30% calcium phosphate, 20-40% kaolin, 10-30% calcium hydroxide, and 10-30% hydrogen peroxide solution. The alginic acid, hydroxypropyl cellulose, ferric sulfate, ferrous sulfate, and hydrogen peroxide solution are mixed and activated, then rapidly mixed with the calcium phosphate, calcium hydroxide, and kaolin. After thorough mixing, the mixture is poured into a mold and cured (e.g., 12-36 hours, specifically 20-28 hours, more specifically 24 hours) to form the cadmium-inhibiting slow-release block. Preferably, the kaolin is washed kaolin. Preferably, the concentration of the hydrogen peroxide solution is 10%.
9. The preparation method according to claim 8, characterized in that, The raw materials used in the method are, by mass fraction, 3% alginic acid, 3% hydroxypropyl cellulose, 3% ferric sulfate, 1.5% ferrous sulfate, 20% calcium phosphate, 30% kaolin, 20% calcium hydroxide and 19.5% hydrogen peroxide solution.
10. The application of the cadmium-inhibiting slow-release block according to any one of claims 1-7, characterized in that, When used in crop cultivation, it is applicable throughout the entire crop growth cycle; preferably, the crop is a vegetable, and preferably, the application dosage is 800 kg / hm2-1600 kg / hm2; preferably, the service life is 2-5 years; preferably, the application method includes placing it in irrigation ditches, placing it in drip irrigation tanks, pre-burying / burying it at the base of the plant, installing it in a net box at the sprinkler inlet, or suspending it in a net bag at the base of the plant; preferably, the cadmium inhibition effect is to reduce the cadmium accumulation in the plant by 67%-88%.