A highly efficient remediation agent for acidic soils and its preparation method
By combining hydroxyapatite-modified biochar, MOF biochar complex, and lime as a remediation agent, the problem of poor efficacy of acid soil conditioners used alone was solved, achieving rapid improvement of soil pH and soil structure while reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI RUIJIE ECOLOGICAL ENVIRONMENT CO LTD
- Filing Date
- 2025-07-16
- Publication Date
- 2026-05-26
AI Technical Summary
Existing soil conditioners are difficult to use alone to achieve significant and comprehensive improvement effects, which may lead to negative consequences. In addition, traditional conditioners are costly and it is difficult to achieve a balance between long-term and short-term effects.
A combined remediation agent using hydroxyapatite-modified biochar, MOF biochar complex, and lime is used to quickly neutralize soil hydrogen ions and increase pH value by adjusting soil acidity, providing nutrients, and improving soil structure, thus achieving both short-term and long-term remediation effects.
It can significantly improve soil acidity, enhance soil fertility, reduce heavy metal toxicity, and increase soil base saturation in a short period of time, thus achieving economically feasible long-term soil improvement.
Smart Images
Figure CN120843114B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soil remediation, and in particular to a highly efficient remediation agent for acidic soils and its preparation method. Background Technology
[0002] Under natural conditions, soil acidification originates from the slow weathering of soil clay minerals, which should be a long and gradual process. However, with the advancement of industrialization, acid deposition has become increasingly severe. Simultaneously, the long-term intensive and uncontrolled use of agricultural soils, along with the irrational application of large amounts of ammonium nitrogen and phosphate fertilizers, has exacerbated the problem, leading to a large influx of exogenous hydrogen ions into the soil environment. Under these circumstances, the soil's nutrient balance cannot be maintained, its structure changes, and its pH gradually decreases. Studies have found that approximately 50% of the world's arable land is acidic. Soil acidification not only threatens soil health but also severely restricts agricultural production and hinders sustainable agricultural development.
[0003] Among the many acidic soil conditioners that have been developed and utilized by humans, lime has the longest history of use. Lime resources are abundant, the mining and processing process is simple, the yield is considerable, and the price is relatively low, making it a common and effective acidic soil conditioner in traditional agricultural production. Lime is alkaline and contains abundant calcium. When applied to the soil, carbonate ions can neutralize hydrogen ions in the acidic soil solution, thereby rapidly increasing the soil pH and improving acidified soil. In the process of replenishing exchangeable calcium in the soil, lime can also react with aluminum ions in the soil to form hydroxide precipitates, reducing the content of exchangeable aluminum in soil colloids and effectively mitigating aluminum damage. It is often used to improve aluminum-rich acidic soils. Furthermore, applying lime helps promote the binding of soil minerals and organic carbon, enhancing the physical protection of organic carbon in acidified soils.
[0004] Biochar is typically alkaline, with a pH value generally between 7 and 10. Its alkaline components mainly exist in the form of carbonates and organic anions, and it possesses a rich porous structure with numerous organic functional groups and a high cation exchange capacity on its surface. Biochar can neutralize and consume excess exchangeable hydrogen and aluminum ions in acidic soils through various mechanisms such as ion exchange, physical adsorption, and surface complexation. This reduces soil acidity, enhances the soil's adsorption capacity for nutrients such as potassium, calcium, and magnesium, increases soil base saturation, improves the soil's acid-base buffering capacity, thereby improving soil fertility, mitigating soil acidification, and reducing the toxicity of heavy metals and other harmful elements to crops.
[0005] In practical applications, using only one or similar acidic soil conditioners often fails to achieve significant and comprehensive improvement effects, and may even bring risks and produce serious negative consequences. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention provides a highly efficient remediation agent for acidic soils and its preparation method.
[0007] This invention is achieved through the following technical solution:
[0008] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar composite, and lime.
[0009] Furthermore, the mass of the hydroxyapatite-modified biochar is 2% to 8% of the mass of the soil to be remediated.
[0010] Furthermore, the mass of the MOF biochar complex is 2% to 8% of the mass of the soil to be remediated.
[0011] Furthermore, the mass of lime is 2% of the mass of the soil to be remediated.
[0012] Furthermore, the mass ratios of the hydroxyapatite-modified biochar, MOF biochar composite, and lime are 6%, 8%, and 2% of the soil mass, respectively.
[0013] Furthermore, the preparation method of the hydroxyapatite-modified biochar is as follows:
[0014] Add 2g of biochar and 20g of hydroxyapatite to 100mL of deionized water, stir for 2h, dry at 80℃, calcine at 700℃ for 6h, wash with deionized water, and dry at 80℃ to obtain hydroxyapatite-modified biochar.
[0015] Further, the preparation method of the biochar is as follows: 2g of cow dung is added to 80mL of deionized water and stirred at 25℃ for 30min. Then, 3g of sodium bicarbonate and 1.270g of L-cysteine hydrochloride are added respectively. The mixed solution is stirred continuously at a constant temperature of 80℃ for 4h, and finally placed in an oven at 60℃ for 48h. Under a nitrogen atmosphere, the mixture is dried at 5℃ for 5min. -1 The biochar was heated to 800℃ at a controlled heating rate and held for 2 hours. After heat treatment, the sample was washed with ethanol and deionized water until neutral, and then dried at 80℃ to obtain biochar.
[0016] Furthermore, the preparation method of the MOF biochar composite is as follows:
[0017] Add 0.4 g of biochar to 2 mL of anhydrous methanol and 18 mL of DMF, and stir vigorously for 30 min. Then, while stirring, add 1 g of H2BDC and 0.568 mL of Ti4(OCH3). 16Continue sonication for another 20 minutes. Transfer the homogeneous solution to a polytetrafluoroethylene-lined autoclave and maintain at 150°C for 18 hours. After cooling to room temperature, accelerate at 7000 rpm. -1 Centrifuge at a speed of 5 min and wash the precipitate with ethanol and DMF, respectively. Dry the precipitate under vacuum at 80 °C for 12 h to obtain the MOF biochar complex.
[0018] Further, the preparation method of the biochar is as follows: 2g of cow dung is added to 80mL of deionized water and stirred at 25℃ for 30min. Then, 3g of sodium bicarbonate and 1.270g of L-cysteine hydrochloride are added respectively. The mixed solution is stirred continuously at a constant temperature of 80℃ for 4h, and finally placed in an oven at 60℃ for 48h. Under a nitrogen atmosphere, the mixture is dried at 5℃ for 5min. -1 The biochar was heated to 800℃ at a controlled heating rate and held for 2 hours. After heat treatment, the sample was washed with ethanol and deionized water until neutral, and then dried at 80℃ to obtain biochar.
[0019] The present invention also provides a method for preparing a highly efficient remediation agent for acidic soil, comprising the following steps: mixing hydroxyapatite-modified biochar, MOF biochar composite and lime, pulverizing and passing through a 125-mesh sieve.
[0020] Compared with existing technologies, this invention has the following advantages and beneficial effects: The combination of hydroxyapatite-modified biochar, MOF biochar complex, and lime creates a synergistic effect among the components. The hydroxyapatite-modified biochar and MOF biochar complex not only regulate soil acidity but also provide abundant nutrients and improve soil structure. Lime can rapidly neutralize hydrogen ions in acidic soils, quickly increasing soil pH, enabling the remediation agent to improve soil acidity in a short time while achieving both short-term and long-term remediation effects. The raw materials for biochar preparation include agricultural waste such as cow dung, which are widely available and inexpensive, realizing the resource utilization of waste. Lime is also a common soil conditioner, relatively inexpensive and readily available, helping to reduce the overall production cost of the remediation agent and improve its economic feasibility and application scope.
[0021] From the preparation of biochar to the synthesis of hydroxyapatite-modified biochar and MOF biochar composites, the process conditions for each step are well-defined and relatively simple. For example, under the parameter control of operations such as stirring, drying, and calcination, the performance and interactions of each component can be effectively guaranteed. Attached Figure Description
[0022] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, are not intended to limit the embodiments of the present invention.
[0023] Figure 1Here is a SEM image of the MOF biochar complex in this invention;
[0024] Figure 2 To show the changes in biomass after 180 days of cultivation;
[0025] Figure 3 Changes in available potassium after 180 days of cultivation;
[0026] Figure 4 The change in nitrate nitrogen after 180 days of cultivation;
[0027] Figure 5 The change in available phosphorus after 180 days of cultivation. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0029] In this invention, lime is calcium hydroxide.
[0030] Example 1
[0031] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar complex, and lime, wherein the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime are 8%, 8%, and 2% of the soil mass, respectively.
[0032] The preparation method of hydroxyapatite-modified biochar is as follows:
[0033] First, 2g of cow dung was added to 80mL of deionized water and stirred at 25℃ for 30min. Then, 3g of sodium bicarbonate and 1.270g of L-cysteine hydrochloride were added. The mixture was stirred continuously at a constant temperature of 80℃ for 4h, and finally placed in an oven at 60℃ for 48h. Under a nitrogen atmosphere, the mixture was then dried at 5℃ for 5min. -1 The biochar was heated to 800℃ at a controlled heating rate and held for 2 hours. After heat treatment, the sample was washed with ethanol and deionized water until neutral, and then dried at 80℃ to obtain biochar.
[0034] Add 2g of biochar and 20g of hydroxyapatite to 100mL of deionized water, stir for 2h, then dry at 80℃, calcine at 700℃, and maintain for 6h. Grind and sieve (120mesh, 0.125mm sieve), wash with deionized water, and dry at 80℃ to obtain hydroxyapatite-modified biochar.
[0035] The preparation method of the MOF biochar complex is as follows:
[0036] First, 2g of cow dung was added to 80mL of deionized water and stirred at 25℃ for 30min. Then, 3g of sodium bicarbonate and 1.270g of L-cysteine hydrochloride were added. The mixture was stirred continuously at a constant temperature of 80℃ for 4h, and finally placed in an oven at 60℃ for 48h. Under a nitrogen atmosphere, the mixture was then dried at 5℃ for 5min. -1 The biochar was heated to 800℃ at a controlled heating rate and held for 2 hours. After heat treatment, the sample was washed with ethanol and deionized water until neutral, and then dried at 80℃ to obtain biochar.
[0037] Add 0.4 g of biochar to 2 mL of anhydrous methanol and 18 mL of DMF, and stir vigorously for 30 min. Then, while stirring, add 1 g of H2BDC and 0.568 mL of Ti4(OCH3). 16 Continue sonication for another 20 minutes. Transfer the homogeneous solution to a polytetrafluoroethylene-lined autoclave and maintain at 150°C for 18 hours. After cooling to room temperature, accelerate at 7000 rpm. -1 Centrifuge at a speed of 5 min and wash the precipitate with ethanol and DMF, respectively. Dry the precipitate under vacuum at 80 °C for 12 h to obtain the MOF biochar complex. Figure 1 SEM image of MOF biochar complex;
[0038] The preparation method of the highly efficient remediation agent for acidic soil is to mix hydroxyapatite-modified biochar, MOF biochar composite and lime, crush and pass through a 125-mesh sieve.
[0039] Example 2
[0040] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar complex, and lime, wherein the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime are 8%, 6%, and 2% of the soil mass, respectively.
[0041] The preparation method is the same as in Example 1.
[0042] Example 3
[0043] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar complex, and lime, wherein the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime are 8%, 2%, and 2% of the soil mass, respectively.
[0044] The preparation method is the same as in Example 1.
[0045] Example 4
[0046] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar complex, and lime, wherein the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime are 6%, 8%, and 2% of the soil mass, respectively.
[0047] The preparation method is the same as in Example 1.
[0048] Example 5
[0049] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar, MOF biochar complex, and lime, wherein the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime are 2%, 8%, and 2% of the soil mass, respectively.
[0050] The preparation method is the same as in Example 1.
[0051] Comparative Example 1
[0052] A highly effective remediation agent for acidic soils, consisting of lime, wherein the mass of lime is 2% of the mass of the soil.
[0053] The preparation method of the highly efficient remediation agent for acidic soil is to crush lime and pass it through a 125-mesh sieve.
[0054] Comparative Example 2
[0055] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar and lime, wherein the mass ratio of hydroxyapatite-modified biochar and lime is 6% and 2% of the soil mass, respectively.
[0056] The preparation method of the highly efficient remediation agent for acidic soil is to crush hydroxyapatite-modified biochar and lime and pass them through a 125-mesh sieve.
[0057] Comparative Example 3
[0058] A highly efficient remediation agent for acidic soils is composed of MOF biochar complex and lime, wherein the mass ratio of MOF biochar complex and lime is 8% and 2% of the soil mass, respectively.
[0059] The preparation method of the highly efficient remediation agent for acidic soil is to crush MOF biochar composite and lime and pass them through a 125-mesh sieve.
[0060] Comparative Example 4
[0061] A highly efficient remediation agent for acidic soils is composed of hydroxyapatite-modified biochar and MOF biochar composite, wherein the mass ratio of hydroxyapatite-modified biochar and MOF biochar composite is 6% and 8% of the soil mass, respectively.
[0062] The preparation method of the highly efficient remediation agent for acidic soil is to pulverize MOF biochar composite and hydroxyapatite modified biochar and pass them through a 125-mesh sieve.
[0063] Test Example 1
[0064] The highly efficient remediation agents prepared in the examples and comparative examples were added to 500g of air-dried soil and mixed. The soil moisture content was adjusted to 60% of field capacity using deionized water. The soil was incubated at a constant temperature indoors, and the moisture content was maintained by weighing once a week. After a certain period of incubation, soil samples were collected for testing. Soil pH was determined using a pH meter; soil organic matter was determined using the potassium dichromate titration method; nitrate nitrogen was determined using ultraviolet spectrophotometry; available phosphorus was determined using the sodium bicarbonate extraction-molybdenum antimony colorimetric method; and available potassium was determined using the ammonium acetate-flame photometric method.
[0065] Changes in biomass after 180 days of cultivation Figure 1 As shown. The change in available potassium after 180 days of cultivation was... Figure 2 As shown. The change in nitrate nitrogen after 180 days of cultivation was... Figure 3 As shown. The change in available phosphorus after 180 days of cultivation was... Figure 4 As shown. The pH changes of the soil after 30, 60, 90, and 180 days of cultivation were influenced by... Figure 1 As shown.
[0066] Table 1. Soil pH changes.
[0067] pH (30 days) pH (60 days) pH (90 days) pH (180 days) Example 1 7.1 6.8 6.7 6.6 Example 2 6.7 6.8 6.8 6.7 Example 3 6.8 7.0 6.5 6.5 Example 4 6.9 6.8 6.5 6.4 Example 5 6.4 6.5 6.2 6.1 Comparative Example 1 6.3 6.5 6.2 6.1 Comparative Example 2 6.52 6.4 6.4 6.2 Comparative Example 3 6.4 6.1 5.9 5.8 Comparative Example 4 5.3 5.2 5.2 5.1
[0068] Depend on Figures 2-5 As shown in Table 1, when the mass ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime in the remediation agent are 6%, 8%, and 2% of the soil mass, respectively, not only is the soil pH adjusted, but biomass, nitrate nitrogen, and available phosphorus are also significantly increased. Compared with other ratios of hydroxyapatite-modified biochar, MOF biochar complex, and lime, it has a better effect.
[0069] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A highly efficient remediation agent for acidic soils, characterized in that, It is composed of hydroxyapatite-modified biochar, MOF biochar composite and lime; The preparation method of the hydroxyapatite modified biochar is as follows: 2g of biochar and 20g of hydroxyapatite are added to 100mL of deionized water, stirred for 2h, dried at 80℃, calcined at 700℃ for 6h, washed with deionized water, and dried at 80℃ to obtain hydroxyapatite modified biochar. The MOF biochar complex was prepared as follows: 0.4 g of biochar was added to 2 mL of anhydrous methanol and 18 mL of DMF, and stirred vigorously for 30 min; then, 1 g of H2BDC and 0.568 mL of Ti4(OCH3) were added while stirring. 16 Continue sonication for another 20 minutes; transfer the homogeneous solution to a polytetrafluoroethylene-lined autoclave and maintain at 150°C for 18 hours; after cooling to room temperature, reflux at 7000 rpm. Centrifuge at 1 for 5 min and wash the precipitate with ethanol and DMF respectively; dry the precipitate under vacuum at 80 °C for 12 h to obtain MOF biochar complex.
2. The highly efficient remediation agent for acidic soils as described in claim 1, characterized in that, The mass of hydroxyapatite-modified biochar is 2% to 8% of the mass of the soil to be remediated.
3. The highly efficient remediation agent for acidic soils as described in claim 1, characterized in that, The mass of the MOF biochar composite is 2% to 8% of the mass of the soil to be remediated.
4. The highly efficient remediation agent for acidic soils as described in claim 1, characterized in that, The mass of lime is 2% of the mass of the soil to be remediated.
5. The highly efficient remediation agent for acidic soils as described in claim 1, characterized in that, The mass ratios of the hydroxyapatite-modified biochar, MOF biochar composite, and lime were 6%, 8%, and 2% of the soil mass, respectively.
6. The highly efficient remediation agent for acidic soils as described in claim 1, characterized in that, The biochar preparation method is as follows: 2g of cow dung is added to 80mL of deionized water and stirred at 25℃ for 30min. Then, 3g of sodium bicarbonate and 1.270g of L are added respectively. Cysteine hydrochloride; the mixed solution was stirred continuously at 80℃ for 4 hours, and then placed in an oven at 60℃ for another 48 hours; under a nitrogen atmosphere, it was dried at 5℃ for 1 minute. The sample was heated to 800℃ at a heating rate of 1 and held for 2 hours. After heat treatment, the sample was washed with ethanol and deionized water until neutral, and then dried at 80℃ to obtain biochar.
7. The method for preparing the highly efficient remediation agent for acidic soil as described in any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing hydroxyapatite-modified biochar, MOF biochar composite and lime, pulverizing and passing through a 125-mesh sieve.