Composite functional material with acidified soil regulating function and preparation method thereof
The composite material prepared by combining hydrothermal and ball milling methods has an inner slow-release structure combined with an outer coating, which solves the problem of short slow-release cycle of existing composite materials, and achieves long-term carbon increase, acid reduction and soil structure improvement. The material is readily available and environmentally friendly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-04-03
AI Technical Summary
Existing composite materials have problems such as short slow-release cycle and need to be repeatedly added in the process of treating soil acidification, and traditional methods may cause soil structure damage and heavy metal pollution.
A material with a long-lasting, sustained-release inner layer was prepared using a hydrothermal method. The core material was selected from materials such as hydroxyapatite, and the outer coating was made of attapulgite powder. The inner and outer layers were bridged by carboxymethyl cellulose to form a sustained-release structure that delayed the alkaline release of the material.
It achieves long-lasting carbon increase and acid reduction effects, improves soil structure, avoids the impact of drastic pH changes on microorganisms, provides long-term soil conditioning function, and the materials are readily available and environmentally friendly.
Smart Images
Figure CN121780179A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of acidic soil conditioners, specifically relating to a composite functional material with acidification soil conditioning function and its preparation method. Background Technology
[0002] Soil acidification leads to soil degradation, decreased fertility, and inhibited plant growth, posing a serious threat to agricultural production, agricultural product quality, and the ecological environment. Traditional organic fertilizers, being the most readily available fertilizers, are used to provide various nutrients and increase yields, and are therefore commonly used to improve soil acidification. However, traditional organic fertilizers have certain drawbacks; they can increase the concentration of heavy metal ions in the soil. Some inorganic industrial residues have also attracted the attention of researchers, but inorganic fertilizers contain a large number of anti-degradation ions, which can easily cause soil compaction, thereby inhibiting the migration rate of nutrients.
[0003] With the continuous development of science and technology, significant progress has been made in the research of functional materials for controlling soil acidification. Currently, the most studied functional materials mainly include alkaline materials, organic materials, and biochar, which can improve soil acidity and alkalinity through different mechanisms.
[0004] Attapulgite powder, as an environmentally friendly natural clay material, has a nano-network structure with numerous micro- and nano-pores. It can adsorb heavy metals through cation exchange capacity or electrostatic interaction. At the same time, as a highly adsorbent clay mineral, it can be directly applied to sandy soil to increase soil cementitious substances, promote the formation of soil aggregates, and enhance the carbon and nitrogen fixation capacity of sandy soil.
[0005] Hydroxyapatite is an apatite mineral with a unique crystal structure that gives it excellent ion exchange properties. Its high specific surface area results in good phosphorus availability and stability, reducing the risk of soil acidification and phosphorus leaching. Furthermore, hydroxyapatite is environmentally friendly and unlikely to cause secondary pollution, making it a novel environmentally functional material for remediating contaminated soils.
[0006] In the process of addressing soil acidification, the application of single-function materials often requires high dosages, which can damage soil structure and negatively impact plant growth, or necessitate continuous annual application of soil conditioners. In recent years, composite materials have gained attention due to their slow-release effects and comprehensive advantages. They can increase soil pH while also reducing heavy metal pollution, improving soil structure and fertility.
[0007] Currently, common methods for preparing composite materials include hydrothermal methods and ball milling methods. Although these methods have advantages such as simple processes and low costs, actual application results show that composite materials prepared by a single method often have problems such as short sustained-release cycles and the need for repeated additions.
[0008] Therefore, it is of great significance to develop a new composite functional material with soil acidification regulation function. Summary of the Invention
[0009] The technical problem this invention aims to solve is to address the shortcomings of existing technologies by further designing and optimizing the materials while retaining the advantages of commonly used traditional preparation methods. First, a long-lasting, slow-release inner layer structure is prepared using a hydrothermal method. The core materials are primarily selected from materials with excellent neutralizing properties for acidic soils, such as hydroxyapatite and calcium phosphate. Then, attapulgite powder is introduced as an external coating slow-release structure using a ball milling method. The inner and outer layers are effectively combined using carboxymethyl cellulose. This material anchors the core materials, such as hydroxyapatite, through the porous structure of the attapulgite powder itself, delaying their alkaline release. Initially, the externally coated attapulgite powder provides a short-term slow-release improvement effect on the soil. As time passes and the environment changes, the attapulgite powder is gradually consumed, effectively exposing the inner slow-release material, which continues to provide carbon-enhancing and acid-reducing effects to the soil, ultimately achieving a long-lasting and excellent effect on acidic soils.
[0010] To address the aforementioned technical problems, this invention discloses a method for preparing a composite functional material with soil acidification regulation function, comprising the following steps:
[0011] S1. Mix the sustained-release material and carboxymethyl cellulose, add deionized water to dissolve and form a mixed solution; add sodium hydroxide solution dropwise to the mixed solution to obtain the reaction solution;
[0012] S2. The reaction solution is transferred to a high-pressure reactor for hydrothermal reaction. After cooling, washing and drying, the slow-release core material is obtained.
[0013] S3. Transfer the slow-release core material and attapulgite powder into a ball mill jar, and after ball milling, the composite functional material is obtained.
[0014] The mass ratio of the sustained-release material to carboxymethyl cellulose is (20~30):1; the concentration of carboxymethyl cellulose in the mixed solution is 0.5~1.5wt%.
[0015] In some embodiments of the present invention, the mass ratio of the sustained-release material to carboxymethyl cellulose is 25:1; and the concentration of carboxymethyl cellulose in the mixed solution is 1 wt%.
[0016] The slow-release material includes any one of hydroxyapatite, calcium phosphate, and calcium hydroxide.
[0017] In some embodiments of the present invention, the sustained-release material is hydroxyapatite or calcium phosphate.
[0018] The volume ratio of the sodium hydroxide solution to the mixed solution is (0.5~1):1; the concentration of the sodium hydroxide solution is 3 mol / L.
[0019] In some embodiments of the present invention, the volume ratio of the sodium hydroxide solution to the mixed solution is 0.75:1.
[0020] The hydrothermal reaction is carried out under the following conditions: temperature 100~120℃, time 24h.
[0021] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 110°C.
[0022] In step S2, the washing conditions are as follows: the product is washed sequentially with deionized water and anhydrous ethanol until the filtrate is neutral; the drying temperature is 50~60℃.
[0023] The mass ratio of the pre-composite material to attapulgite powder is (1.5~3):1.
[0024] In some embodiments of the present invention, the mass ratio of the pre-composite material to attapulgite powder is 2:1.
[0025] In some embodiments of the present invention, the attapulgite powder is a commercially available 200-mesh chemical reagent.
[0026] The ball milling conditions are as follows: ball-to-material ratio 1:(80~120), rotation speed 250~350 r / min, alternating forward and reverse ball milling, and total ball milling time 150~210 min.
[0027] In some embodiments of the present invention, the ball milling conditions are as follows: a material-to-ball ratio of 1:100, a rotation speed of 300 r / min, alternating forward and reverse ball milling for 90 min each, and a total ball milling time of 180 min.
[0028] In the preparation system provided by this invention, the hydrothermal method prepares a slow-release core through the effective bridging effect of environmentally friendly carboxymethyl cellulose, providing a long-lasting slow-release effect; while the ball milling process encapsulates the above-mentioned slow-release core material, it effectively increases the oxygen-containing groups on the surface of the material, ultimately endowing the material with the function of rapidly regulating soil pH and a long-lasting slow-release effect.
[0029] Furthermore, the composite functional materials prepared by the above preparation method are also within the scope of protection of this invention.
[0030] Specifically, in some embodiments of the present invention, composite functional materials were successfully prepared using the above-described preparation method. Specifically, the inner long-lasting slow-release structure of the material was prepared via a hydrothermal method, and then attapulgite powder was introduced as an outer coating slow-release structure via ball milling. The inner and outer layers were effectively combined using carboxymethyl cellulose. Characterization of the composite functional material's own pH, its slow-release performance in an aqueous system, and its slow-release performance in a soil system demonstrated the excellent long-lasting carbon-increasing and acid-reducing effect of the composite functional material provided by the present invention on acidic soils.
[0031] Beneficial effects:
[0032] 1. This invention, through further design and optimization of the traditional material preparation process, uses environmentally friendly organic material carboxymethyl cellulose to bridge inorganic slow-release materials such as hydroxyapatite and attapulgite powder, forming an inner and outer layer composite structure with excellent slow-release effect. When applied to the soil, it achieves a good long-term effect of increasing carbon and reducing acidity. Specifically, by introducing the porous nanostructure of attapulgite powder, alkaline materials such as hydroxyapatite are anchored, significantly slowing down the release rate of alkaline substances. Simultaneously, the structure of attapulgite powder itself provides a short-term slow-release regulation effect. As time progresses and the environment changes, the attapulgite powder is gradually consumed, and the inner layer of slow-release material is effectively exposed, continuing to provide carbon increase and acid reduction for the soil. Ultimately, it achieves a long-term excellent effect of increasing carbon and reducing acidity in acidic soils, overcoming the shortcomings of single-function materials such as short release cycles and the need for repeated replenishment.
[0033] 2. The combination of multiple materials avoids the impact of drastic pH changes on soil microbial ecology. The addition of attapulgite powder enhances the formation of soil aggregates, improves soil pore structure and stability, thereby improving soil water and fertilizer retention capacity, promoting root development, and ensuring short-term slow-release effects. At the same time, other slow-release materials are slowly exposed over time and with changes in the environment under the encapsulation of attapulgite powder and carboxymethyl cellulose, providing strong support for long-term slow release.
[0034] 3. The hydroxyapatite, calcium phosphate, carboxymethyl cellulose and attapulgite powder used in this invention are all commercially available and mature industrial products. The raw materials are readily available and do not require complex modification. Furthermore, the preparation method of the composite material in this system combines common ball milling and hydrothermal methods, and further optimizes the parameters and the compounding ratio of organic and inorganic materials to give full play to the properties of each material. The process system is mature and simple, and is easy to scale up production.
[0035] 4. The material produced by this invention is environmentally friendly and non-toxic, and its addition has no significant impact on the microbial community of the soil environment. Attached Figure Description
[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.
[0037] Figure 1 A flowchart of the preparation method provided in an embodiment of the present invention.
[0038] Figure 2 This is a SEM image of the composite functional material prepared in the embodiments of the present invention. Detailed Implementation
[0039] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.
[0040] Example 1:
[0041] This embodiment provides a method for preparing a composite functional material with soil acidification regulation function. Figure 1 The flowchart of the preparation method provided in this embodiment is as follows:
[0042] Preparation of the composite functional material: This composite functional material was prepared using a hydrothermal ball milling composite method. The hydrothermal method involved mixing hydroxyapatite and carboxymethyl cellulose at a mass ratio of 25:1, dissolving them in deionized water to form a mixed solution, and continuously stirring magnetically for 30 minutes until the mixed solution was uniform and transparent. A 3 mol / L sodium hydroxide solution was then added dropwise to the resulting mixed solution, with a volume ratio of sodium hydroxide solution to the mixed solution of approximately 0.75:1, and stirring was continued for 1 hour to obtain a reaction solution. The obtained reaction solution was transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After the reaction was completed, the mixture was cooled, and the product was washed sequentially with deionized water and anhydrous ethanol until the filtrate was neutral. The controlled-release core material was obtained after drying at 50°C.
[0043] The ball milling method is as follows: the dried slow-release core material and attapulgite powder are added to the ball milling jar at a mass ratio of 2:1, wherein the mass ratio of material to milling beads is set to 1:100, the rotation speed is set to 300 r / min, and the total ball milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After the ball milling is completed, the composite functional material is collected.
[0044] The microstructure of the composite functional material prepared in this embodiment was characterized using scanning electron microscopy (SEM). Figure 2 This is a SEM image of the composite functional material prepared in this embodiment, where ATP is attapulgite powder, CMC is carboxymethyl cellulose, and HAP is hydroxyapatite. Figure 2It can be seen that both attapulgite powder and hydroxyapatite have porous surfaces, while the bridging carboxymethyl cellulose has a smooth surface. These characteristics provide good sites for the bonding and anchoring of the materials. At the same time, the porous structure of the raw materials also provides factual evidence for the composite functional material to enhance soil water and fertilizer retention capacity and long-term slow-release performance. The final prepared composite functional material also retains these structural characteristics well.
[0045] Example 2:
[0046] This embodiment provides a method for preparing a composite functional material with soil acidification regulation function, the specific steps of which are as follows:
[0047] Preparation of the composite functional material: This composite functional material was prepared using a hydrothermal ball milling composite method. The hydrothermal method involved mixing calcium phosphate and carboxymethyl cellulose at a mass ratio of 25:1, dissolving them in deionized water to form a mixed solution, and continuously stirring magnetically for 30 minutes until the mixed solution was uniform and transparent. A 3 mol / L sodium hydroxide solution was then added dropwise to the resulting mixed solution, with a volume ratio of sodium hydroxide solution to the mixed solution of approximately 0.75:1, and stirring was continued for 1 hour to obtain a reaction solution. The obtained reaction solution was transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After the reaction was completed, the mixture was cooled, and the product was washed sequentially with deionized water and anhydrous ethanol until the filtrate was neutral. The controlled-release core material was obtained after drying at 50°C.
[0048] The ball milling method is as follows: the dried slow-release core material and attapulgite powder are added to the ball milling jar at a mass ratio of 2:1, wherein the mass ratio of material to milling beads is set to 1:100, the rotation speed is set to 300 r / min, and the total ball milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After the ball milling is completed, the composite functional material is collected.
[0049] Example 3:
[0050] This embodiment provides a method for preparing a composite functional material with soil acidification regulation function, the specific steps of which are as follows:
[0051] Preparation of the composite functional material: This composite functional material was prepared using a hydrothermal ball milling composite method. The hydrothermal method involved mixing calcium hydroxide and carboxymethyl cellulose at a mass ratio of 25:1, dissolving them in deionized water to form a mixed solution, and continuously stirring magnetically for 30 minutes until the mixed solution was uniform and transparent. A 3 mol / L sodium hydroxide solution was then added dropwise to the resulting mixed solution, with a volume ratio of sodium hydroxide solution to the mixed solution of approximately 0.75:1, and stirring was continued for 1 hour to obtain a reaction solution. The obtained reaction solution was transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After the reaction was completed, the mixture was cooled, and the product was washed sequentially with deionized water and anhydrous ethanol until the filtrate was neutral. The controlled-release core material was obtained after drying at 50°C.
[0052] The ball milling method is as follows: the dried slow-release core material and attapulgite powder are added to the ball milling jar at a mass ratio of 2:1, wherein the mass ratio of material to milling beads is set to 1:100, the rotation speed is set to 300 r / min, and the total ball milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After the ball milling is completed, the composite functional material is collected.
[0053] Comparative Example 1:
[0054] This comparative experiment uses commercially available raw material attapulgite powder as a composite functional material to compare its performance.
[0055] Comparative Example 2:
[0056] This comparative experiment uses hydroxyapatite, a single commercially available raw material, as the composite functional material for performance comparison.
[0057] Comparative Example 3:
[0058] This comparative experiment uses carboxymethyl cellulose, a single commercially available raw material, as the composite functional material for performance comparison.
[0059] Comparative Example 4:
[0060] This comparative example synthesizes composite functional materials using the preparation method of Example 1. The difference is that this comparative example uses a one-step ball milling method to prepare the composite functional materials. The specific steps are as follows: approximately 50 parts of hydroxyapatite, 2 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder are added to a ball mill jar, wherein the mass ratio of materials to milling beads is set to 1:100, the rotation speed is set to 300 r / min, and the total ball milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After ball milling is completed, the composite functional materials are collected.
[0061] Comparative Example 5:
[0062] This comparative example synthesizes composite functional materials using the same preparation method as Example 1. The difference lies in that this comparative example employs a one-step hydrothermal method to prepare the composite functional materials. Specifically, approximately 50 parts of hydroxyapatite and 2 parts of carboxymethyl cellulose are dissolved in deionized water to form a mixed solution. The solution is continuously stirred magnetically for 30 minutes until it becomes uniform and transparent. Then, approximately 25 parts of attapulgite powder are added, and a 3 mol / L sodium hydroxide solution is added dropwise to the resulting solution. The volume ratio of sodium hydroxide solution to the mixed solution is approximately 0.75:1, and the mixture is continuously stirred for 1 hour. The resulting mixed solution is transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After the reaction is complete, the mixture is cooled, and the product is washed sequentially with deionized water and anhydrous ethanol until the filtrate is neutral. The product is then dried at 50°C to obtain the composite functional material.
[0063] Comparative Example 6:
[0064] The comparative example uses the preparation method of Example 1 to synthesize composite functional materials. The difference is that the comparative example uses a simple physical blending method to prepare composite functional materials. The specific steps are as follows: about 50 parts of hydroxyapatite, 2 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder are added to an agate mortar, ground and sieved, and then the composite functional materials are collected.
[0065] Comparative Example 7:
[0066] This comparative example uses a one-step ball milling method and adjusts the composite material ratio to prepare a similar composite functional material, whose performance is compared with the composite functional material in Example 1. The specific steps are as follows: Approximately 50 parts of hydroxyapatite, 25 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder are added to a ball mill jar, with the material-to-milling-bead mass ratio set to 1:100. The rotation speed is set to 300 r / min, and the total ball milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After ball milling, the composite functional material is collected.
[0067] Comparative Example 8:
[0068] This comparative experiment uses commercially available calcium phosphate as a single composite functional material to compare performance.
[0069] Comparative Example 9:
[0070] This comparative example synthesizes composite functional materials using the preparation method of Example 2. The difference lies in that this comparative example employs a one-step ball milling method. Specifically, approximately 50 parts of calcium phosphate, 2 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder are added to a ball mill jar. The mass ratio of materials to milling beads is set to 1:100, the rotation speed is set to 300 r / min, and the total milling time is set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After milling, the composite functional material is collected.
[0071] Comparative Example 10:
[0072] This comparative example synthesizes a composite functional material using the same preparation method as Example 2. The difference lies in the fact that this comparative example employs a one-step hydrothermal method. Specifically, approximately 50 parts of calcium phosphate and 2 parts of carboxymethyl cellulose are dissolved in deionized water to form a mixed solution. The solution is then continuously stirred magnetically for 30 minutes until it becomes uniform and transparent. Next, approximately 25 parts of attapulgite powder are added, and a 3 mol / L sodium hydroxide solution is added dropwise to the resulting solution. The volume ratio of sodium hydroxide solution to the mixed solution is approximately 0.75:1, and the mixture is continuously stirred for 1 hour. The resulting mixed solution is then transferred to a high-pressure reactor and reacted at 110°C for 24 hours. After the reaction is complete, the mixture is cooled, and the product is washed sequentially with deionized water and anhydrous ethanol until the filtrate is neutral. The product is then dried at 50°C to obtain the composite material.
[0073] Comparative Example 11:
[0074] The comparative example uses the preparation method of Example 2 to synthesize composite functional materials. The difference is that the method used in this comparative example is simple physical blending. The specific steps are as follows: about 50 parts of calcium phosphate, 2 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder are added to an agate mortar, ground and sieved, and then the composite functional material is collected.
[0075] Comparative Example 12:
[0076] This comparative example uses a one-step ball milling method and adjusts the composite material ratio to prepare a similar composite functional material, whose performance is compared with the composite functional material in Example 2. Approximately 50 parts of calcium phosphate, 25 parts of carboxymethyl cellulose, and 25 parts of attapulgite powder were added to a ball mill jar, with the material-to-milling-bead mass ratio set to 1:100. The rotation speed was set to 300 r / min, and the total ball milling time was set to 180 minutes, including 90 minutes of forward rotation and 90 minutes of reverse rotation. After ball milling, the composite functional material was collected.
[0077] Performance verification:
[0078] 1. The pH values of the composite functional materials prepared in Examples 1-3 and Comparative Examples 1-12 were determined. The specific steps are as follows: 0.5 g of the prepared composite functional material was weighed into a 50 ml centrifuge tube, and then 5 ml of deionized water was added, i.e., the solid-liquid ratio was set to 1:10. The pretreated sample was placed in a shaker and mixed at a speed of 200 r / min for 1 h. After mixing, the sample was removed and allowed to stand for 30 min before the pH value of the supernatant was measured. Table 1 shows the pH values of the composite functional materials prepared in Examples 1-3 and Comparative Examples 1-12. As can be seen from Table 1, the materials prepared by the aforementioned preparation method in Examples 1-3 have higher pH values than most of the comparative examples, indicating that this preparation method has certain advantages. However, the data shows that some comparative examples also have relatively good pH values. Therefore, the examples and comparative examples with higher pH values were selected for subsequent water system slow-release experiments to further verify the long-term slow-release performance of the composite materials prepared by the method of the examples.
[0079] Table 1. pH values of the composite functional materials prepared in Examples 1-3 and Comparative Examples 1-12
[0080] Group pH Example 1 10.65 Example 2 9.82 Example 3 12.58 Comparative Example 1 8.48 Comparative Example 2 6.98 Comparative Example 3 7.27 Comparative Example 4 10.12 Comparative Example 5 9.74 Comparative Example 6 9.28 Comparative Example 7 9.46 Comparative Example 8 8.62 Comparative Example 9 9.63 Comparative Example 10 10.12 Comparative Example 11 8.89 Comparative Example 12 9.59
[0081] Since the main functional raw material in Example 3 is calcium hydroxide, it is overly alkalized compared to the composite functional materials prepared in Examples 1 and 2. When applied to the soil, it is likely to cause changes in the soil microbial community. Therefore, it was discarded in the subsequent water system verification and soil system verification experiments.
[0082] Further verification tests were conducted on the composite functional materials of Examples 1-2 and Comparative Examples 4, 5, 7, 9, 10 and 12, which had better pH values, in subsequent water and soil systems.
[0083] 2. The aqueous system sustained-release performance of the composite functional materials selected from Examples 1-2 and Comparative Examples 4, 5, 7, 9, 10, and 12 was verified. The specific steps are as follows: Weigh 0.5g of each composite functional material into a 50ml centrifuge tube, then add 5ml of deionized water, i.e., the solid-liquid ratio is set to 1:10. Place the pretreated sample in a shaker and mix thoroughly, setting the speed to 200r / min and the time to 1h. After mixing, remove the sample and let it stand for 30min, then measure the pH value of the supernatant. Measure and record the data daily. When the measured pH value shows a continuous decreasing trend, use a low concentration of hydrochloric acid to adjust the pH value to around 7, and continue measuring the next day. By repeatedly adjusting the pH value to neutral and observing whether the pH value rises again, the sustained-release performance of the material can be preliminarily judged.
[0084] Table 2 shows the water system slow-release experimental data of the composite functional materials of Examples 1-2 and Comparative Examples 4, 5, 7, 9, 10 and 12. As can be seen from Table 2, after repeatedly adjusting the pH value of the water system by artificial acid addition, the screened materials can be gradually restored to the alkaline level, indicating that the various experimental materials prepared have a certain slow-release effect and can be further verified in the soil system.
[0085] Table 2. Water system slow-release experimental data of composite functional materials in Examples 1-2 and Comparative Examples 4-5, 7, 10-11, and 13.
[0086] Group Days Example 1 Example 2 Comparative Example 4 Comparative Example 5 Comparative Example 7 Comparative Example 9 Comparative Example 10 Comparative Example 12 1 10.61 8.13 9.90 9.75 9.38 9.54 9.80 9.54 2 10.59 8.46 9.83 9.93 9.37 9.38 10.02 9.13 3 10.58(7.14) 8.52 9.85 9.95 8.86(6.76) 9.36(6.94) 10.13 9.18(7.01) 4 8.34 8.62 9.91 10.00 7.78 8.29 10.25 7.89 5 8.52 8.58(7.09) 9.72(7.28) 9.89(7.07) 7.88 8.30 10.16(7.10) 8.27 6 8.74 8.35 8.41 8.84 7.85 8.40 8.08 8.25 7 8.78 8.40 8.49 8.82 7.78 8.32 8.22 8.21 8 8.87 8.46 8.53 8.85 7.61 8.31 8.25 8.15 9 8.89 8.50 8.53 8.86 7.63 8.35 8.25 8.16
[0087] Note: Data in parentheses in the table indicate that after the measurement results showed a continuous downward trend, the pH was artificially adjusted to around neutral using a weak acid.
[0088] 3. After further screening based on the results of the water system slow-release experiment, the functional materials prepared in Examples 1-2 and Comparative Examples 1-5, 8-10, and 12 of this invention were selected for soil system performance verification. Comparative Examples 1-3 and Comparative Example 8 were not screened using the water system slow-release experiment because the materials in these four comparative examples are the four raw materials of the composite functional materials in the preparation examples. They were added to the soil to compare whether the composite functional materials have a better long-term slow-release effect compared to single raw materials. The specific steps are as follows: After naturally air-drying the collected Northeast black soil, impurities were removed and the soil was sieved through a 10-mesh sieve. A certain amount of the sieved soil was weighed into a clean beaker. The composite functional material prepared in the above steps was added to the weighed beaker at 5‰ of the soil weight. A blank control group without any added materials was set up. The pH change of the cultured soil sample was measured over a period of time to preliminarily determine whether the material has a certain regulatory effect on acidified soil. The sampling time was set at 1 day, 10 days, 20 days, and 30 days.
[0089] The aforementioned Northeast black soil was collected from the Keshan Branch of the Heilongjiang Academy of Agricultural Sciences, No. 33 Chunfeng Street, Keshan County, Qiqihar City, Heilongjiang Province (longitude 125.83, latitude 48.02). The initial pH value of the collected soil was 5.26. It should be noted that the Northeast black soil mentioned includes, but is not limited to, the Northeast black soil described in the embodiments of this invention. Any soil that can be used in the prior art to determine whether a material has a certain regulating effect on acidified soil can be used in this invention.
[0090] The method for determining the soil pH value is as follows: Weigh 10.00 g of the soil cultured in the beaker into an Erlenmeyer flask, then add 25 ml of 0.01 mol / L calcium chloride solution to the soil, mix manually, and let stand for 30 min. After standing, use a calibrated pH meter to measure the pH value of the supernatant and record the data.
[0091] Table 3 shows the soil system slow-release experimental data of the composite functional materials in Examples 1-2 and Comparative Examples 1-5, 8-10, and 12. As shown in Table 3, the pH value of all added material groups increased to varying degrees compared to the blank control group (i.e., the blank soil group). Among them, Examples 1 and 2 showed better overall effects compared to the other material groups. Comparative Examples 4 and 10, although also showing good carbon-enhancing effects, exhibited a downward trend over time, belonging to the experimental materials with short-term slow-release effects mentioned in the background art. In contrast, the pH values of Examples 1 and 2 remained relatively stable and showed a certain upward trend, demonstrating good short-term slow-release effects while achieving the expected long-term acid-reducing effect.
[0092] Table 3. Slow-release experimental data of the soil system of composite functional materials in Examples 1-2 and Comparative Examples 1-5, 8-10, and 12.
[0093] Tianzu Group D1pH group 1 D1pH group 2 D10pH group 1 D10pH group 2 D20pH group 1 D20pH group 2 D30pH group 1 D30pH group 2 Example 1 6.19 6.29 6.49 6.24 6.35 6.37 6.42 6.43 Example 2 6.64 6.47 6.50 6.48 6.56 6.53 6.58 6.56 Comparative Example 1 5.82 5.79 6.09 5.96 6.08 5.99 5.93 5.85 Comparative Example 2 4.87 4.84 5.43 5.44 5.43 5.45 5.47 5.48 Comparative Example 3 5.29 5.28 5.32 5.35 5.36 5.35 5.36 5.32 Comparative Example 4 6.80 6.83 6.77 6.72 6.72 6.65 6.69 6.64 Comparative Example 5 5.88 5.68 5.72 5.64 5.81 5.70 5.73 5.75 Comparative Example 8 5.52 5.60 5.63 5.53 5.66 5.65 5.60 5.67 Comparative Example 9 6.69 6.63 6.45 6.48 6.31 6.24 6.36 6.32 Comparative Example 10 5.87 5.93 5.91 5.95 5.90 5.90 6.42 6.21 Comparative Example 12 6.33 6.34 5.93 6.18 6.08 5.84 6.05 6.07 control group 5.27 5.25 5.41 5.31 5.36 5.31 5.31 5.30
[0094] In this invention, a sustained-release material and a sustained-release core material of carboxymethyl cellulose are first prepared using a hydrothermal method. During the hydrothermal process, carboxymethyl cellulose, as an organic compound, fully exerts its binding effect, tightly binding with the sustained-release material to form the internal sustained-release structure of the composite material. After this reaction step is completed, attapulgite powder is introduced as an external coating sustained-release structure through ball milling, and the inner and outer layers are effectively bonded by carboxymethyl cellulose. This material anchors the core material such as hydroxyapatite through the porous structure of attapulgite powder itself, delaying its alkaline release.
[0095] When composite functional materials are added to soil, attapulgite powder is the first to take effect. Due to the release of its own alkaline groups, attapulgite powder achieves a short-term slow-release effect on acidic soils. Simultaneously, attapulgite powder can utilize its nanofiber structure to slow the dissolution rate of slow-release materials such as hydroxyapatite. Furthermore, with continuous changes in time and environment, as attapulgite powder is consumed, the internal encapsulated materials are gradually exposed and slowly release alkaline groups. For example, the hydroxyapatite in the composite functional materials can gradually dissolve in the soil, slowly releasing Ca2+. 2+ and PO4 3- Effectively neutralizes H + It improves soil acidification, thereby achieving a long-lasting slow-release effect.
[0096] This invention provides a composite functional material with soil acidification regulation function and its preparation method. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.
Claims
1. A method for preparing a composite functional material with soil acidification regulation function, characterized in that, Includes the following steps: S1. Mix the sustained-release material and carboxymethyl cellulose, add deionized water to dissolve and form a mixed solution; add sodium hydroxide solution dropwise to the mixed solution to obtain the reaction solution; S2. The reaction solution is transferred to a high-pressure reactor for hydrothermal reaction. After cooling, washing and drying, the slow-release core material is obtained. S3. Transfer the slow-release core material and attapulgite powder into a ball mill jar, and after ball milling, the composite functional material is obtained.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the sustained-release material to carboxymethyl cellulose is (20~30):1; the concentration of carboxymethyl cellulose in the mixed solution is 0.5~1.5wt%.
3. The preparation method according to claim 2, characterized in that, The sustained-release material includes any one of hydroxyapatite, calcium phosphate, and calcium hydroxide.
4. The preparation method according to claim 1, characterized in that, The volume ratio of the sodium hydroxide solution to the mixed solution is (0.5~1):1; the concentration of the sodium hydroxide solution is 3 mol / L.
5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out under the following conditions: temperature 100~120℃, time 24h.
6. The preparation method according to claim 1, characterized in that, In S2, the washing conditions are as follows: the product is washed sequentially with deionized water and anhydrous ethanol until the filtrate is neutral; the drying temperature is 50~60℃.
7. The preparation method according to claim 1, characterized in that, The mass ratio of the sustained-release core material to attapulgite powder is (1.5~3):
1.
8. The preparation method according to claim 1, characterized in that, The ball milling conditions are as follows: material-to-ball ratio 1:(80~120), rotation speed 250~350 r / min, alternating forward and reverse ball milling, and total ball milling time 150~210 min.
9. The composite functional material prepared by the preparation method according to any one of claims 1 to 8.