A composite functional material for synergistically controlling and inhibiting loss of soil carbon, nitrogen and phosphorus and a preparation method and application thereof
By using composite materials of engineered biochar, zeolite, wollastonite, iron powder, and humic acid, the problem of soil carbon, nitrogen, and phosphorus loss has been solved, achieving efficient fixation and reducing non-point source pollution in farmland. The materials are readily available and inexpensive.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INSTITUTE OF ENVIRONMENT AND SUSTAINABLE DEVELOPMENT IN AGRICULTURE CAAS
- Filing Date
- 2026-03-03
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies are insufficient to effectively control the loss of carbon, nitrogen, and phosphorus in the soil, leading to severe non-point source pollution in farmland, and there is a lack of efficient functional materials suitable for farmland.
A composite material consisting of engineered biochar, zeolite, wollastonite, iron powder, and humic acid is used to achieve a synergistic effect through a specific preparation method, thereby improving the soil's ability to fix carbon, nitrogen, and phosphorus.
It achieves efficient fixation of carbon, nitrogen, and phosphorus in soil, reduces non-point source pollution emissions from farmland, and uses readily available, inexpensive, and highly adaptable materials.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of agricultural non-point source pollution control technology, and relates to a composite functional material that synergistically controls the loss of carbon, nitrogen and phosphorus from soil, its preparation method and application. Background Technology
[0002] Organic matter, phosphorus (P), and nitrogen (N) in soil are essential nutrients for agricultural growth. The application of chemical fertilizers such as nitrogen and phosphorus fertilizers, as well as organic fertilizers, plays a crucial role in supporting normal agricultural production. At the same time, nutrients such as nitrogen, phosphorus, and dissolved organic carbon that are not absorbed by plants enter surface water bodies through agricultural runoff, leading to eutrophication and threatening agricultural ecosystems and water environment safety. The loss of carbon, nitrogen, and phosphorus from farmland has become a key focus and challenge in the prevention and control of non-point source pollution.
[0003] Based on existing research on non-point source pollution, the main technologies for reducing non-point source pollution in farmland include dynamic monitoring devices for non-point source pollution, intelligent monitoring systems for nitrogen and phosphorus in water bodies, and risk assessment methods. These technologies primarily involve optimizing fertilization regimes, controlling fertilizer application rates, constructing ecological buffer zones, and applying adsorbent or slow-release materials. Among these, the application of functional soil amendments has received widespread attention due to its advantages such as ease of operation and wide applicability. CN200810180021.0 discloses a method and reactor for ozone-coupled ASBR / SBR nitrogen and phosphorus sludge reduction water treatment. This provides a reactor capable of sludge reduction and achieving nitrogen and phosphorus standards in effluent. Specifically, it is an ozone-coupled ASBR / SBR nitrogen and phosphorus sludge reduction water treatment reactor, which integrates an ASBR, an SBR biological device, and an ozone lysis device. Using this method and reactor to treat domestic sewage, with a total HRT of approximately 12 h and an ozone dosage of approximately 0.02-0.06 mg / mg·SS (sludge), it ensures that COD, nitrogen, and phosphorus emissions meet standards while reducing sludge volume by 65%. CN202410017144.1 discloses a non-uniform fertilization method for treating ground-source pollution on sloping farmland. It determines the type of cultivated crop and fertilization interval based on the slope of the target treatment area, and determines the fertilization amount at the top of the slope of each plot based on the soil nutrient background value. This method effectively reduces ground-source pollution on sloping farmland. CN200810224313.X discloses a method for efficiently and conveniently controlling non-point source pollution using iron oxide nanomaterials. This method primarily utilizes non-toxic, easily biodegradable, and inexpensive polymers and common iron salts as raw materials. Through a simple synthesis technique, nanomaterials of iron oxide are prepared. This technique allows the material to be dispersed in the subsurface layer of soil, forming a soil wall containing iron oxide nanomaterials. This wall adsorbs phosphorus from phosphorus-containing water flowing through it, thereby controlling phosphorus non-point source pollution caused by excessive use of pesticides and fertilizers, human and animal excrement, and domestic sewage discharge. CN201911116409.9 discloses the preparation of modified sludge hydrothermal carbon material and its application in non-point source pollution reduction. It mainly involves mixing anaerobic digested wet sludge with a reaction medium solution containing 0.8-1.2M magnesium citrate solution and 0.8-1.2% H2SO4, and then hydrothermally carbonizing the mixture in a high-pressure reactor for 1-2 hours to obtain the modified sludge hydrothermal carbon material. Applying this material to paddy field soil can inhibit ammonia volatilization, reduce nitrogen loss from paddy field surface water, and improve the nitrogen utilization efficiency of rice, playing a positive role in non-point source pollution reduction. However, since sludge often contains heavy metals and other harmful substances, the potential secondary risks it poses cannot be ignored. Overall, there are few highly efficient functional materials that can be used to control non-point source pollution loss from farmland, especially environmental functional materials that can synergistically control the loss of carbon, nitrogen, and phosphorus from soil.
[0004] Biochar, a carbon-based material produced by the pyrolysis of agricultural and forestry waste, possesses characteristics such as large specific surface area, well-developed pore structure, and abundant surface functional groups, showing potential in nutrient adsorption, slow release, and reduction of nutrient loss. Although unmodified raw biochar has limited adsorption capacity for anionic nutrients (such as nitrate and phosphate), and its effect on reducing non-point source pollution in farmland is limited, surface modification design and functional optimization of biochar materials to enhance their adsorption and fixation capacity for pollutants has become a promising development direction. The fixation performance of biochar for nitrogen and phosphorus nutrients in soil depends on many factors, such as specific surface area, pore structure, and surface functional groups, all of which are highly correlated with its fixation performance. Therefore, improving the adsorption capacity of biochar by altering its material composition, functional group types and ratios, and porous surface characteristics through physical or chemical methods has become a new research hotspot. Current research and applications of intelligent engineered biochar are mostly concentrated in the field of water pollution control. Their preparation conditions, material structures, and application methods are primarily designed for wastewater treatment processes. However, for reducing non-point source pollution in farmland, truly mature and applicable technologies are still scarce, making it difficult to meet the objective need for sustained reduction of farmland non-point source pollution. Therefore, developing a composite functional material based on engineered biochar that has a simple preparation process, low cost, and stable performance is an urgent technical problem to be solved in this field. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite functional material that synergistically controls the loss of carbon, nitrogen, and phosphorus from soil, as well as its preparation method and application.
[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a composite functional material for synergistically controlling the loss of carbon, nitrogen and phosphorus from soil. The components of the composite functional material include: engineered biochar, zeolite, wollastonite, iron powder and humic acid.
[0007] Preferably, the zeolite mainly contains active SiO2 and Al2O3 components.
[0008] Preferably, the main components of the wollastonite are CaO and SiO2.
[0009] Preferably, the iron powder is cast iron filings with a purity of 98%.
[0010] Preferably, the humic acid has an ash content of 10%, a moisture content of 8%, and an iron content of 0.3%.
[0011] Preferably, the mass ratio of the engineered biochar, zeolite, wollastonite, iron powder, and humic acid is (0.5-3):(0.5-2):(0.5-2):(0.5-2):1 (wherein, the specific value of 0.5-3 can be 0.5, 1, 1.5, 2, 2.5, 3, etc.; the specific value of 0.5-2 can be 0.5, 1, 1.5, 2, etc.).
[0012] Preferably, the engineered biochar is obtained by the following preparation method: (1) Agricultural waste biomass was mixed with iron salt solution and impregnated to obtain pretreated modified biochar; (2) The pretreated modified biochar was mixed with the LDH precursor solution and aged to obtain engineered biochar. The LDH precursor solution was a metal salt solution containing trivalent and divalent metal ions.
[0013] This invention creatively designs a composite functional material for synergistically controlling the loss of carbon, nitrogen, and phosphorus from soil. This composite material, through the synergistic effect of five materials—engineered biochar, zeolite, wollastonite, iron powder, and humic acid—can simultaneously and efficiently immobilize carbon, nitrogen, and phosphorus in the soil, and effectively reduce the leaching loss of these elements, thereby reducing non-point source pollution emissions from farmland. This achieves highly efficient control over the loss of dissolved organic carbon, nitrogen, and phosphorus nutrients from the soil. Compared to any single component, the composite material exhibits superior immobilization effects on soil carbon, nitrogen, and phosphorus; furthermore, the use of specific engineered biochar provides even more efficient immobilization of these elements. Furthermore, the engineered biochar preparation method designed in this invention is simple, uses readily available raw materials, is highly operable, and has strong applicability.
[0014] Preferably, the agricultural waste biomass in step (1) includes core biomass and basic biomass; the core biomass is selected from any one or a combination of at least two of spirulina residue, soybean protein residue, and brewer's yeast residue; the basic biomass is selected from any one or a combination of at least two of bamboo shavings, rice, corn stalks, and wheat crop stalks.
[0015] Preferably, the core biomass is selected from a combination of spirulina residue and soybean protein residue.
[0016] When spirulina residue and soybean protein residue are combined and used together as core biomass, they can have a synergistic effect, significantly improving iron salt loading efficiency and carbon, nitrogen and phosphorus adsorption-fixation capacity. Compared with single biomass, they have more functional sites, stable structure and low cost.
[0017] Preferably, the mass ratio of spirulina residue to soybean protein residue is 1:(0.5-3) (e.g., 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.).
[0018] Preferably, the mass ratio of the core biomass to the basic biomass is 1:(0.5-2) (e.g., 1:0.5, 1:1, 1:1.5, 1:2, etc.).
[0019] Preferably, the pyrolysis temperature in step (1) is 400-800℃ (e.g., 400℃, 500℃, 600℃, 700℃, 800℃, etc.), and the time is 1.5-2.5 h (e.g., 1.5 h, 2 h, 2.5 h, etc.).
[0020] Preferably, the iron salt solution in step (1) comprises a mixed solution of ferrous iron and ferric iron.
[0021] Preferably, the molar ratio of ferrous iron to ferric iron in the iron salt solution is 1:(1-3) (e.g., 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.).
[0022] Preferably, the mass ratio of agricultural waste biomass and iron salt used in the iron salt solution in step (1) is 1:(0.5-3) (e.g., 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.).
[0023] Preferably, the soaking time in step (1) is 10-24 h (e.g., 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, etc.), and the temperature is 25-35℃ (e.g., 25℃, 27℃, 29℃, 31℃, 33℃, 35℃, etc.).
[0024] Preferably, the pH value of the solution adjusted in step (1) is 5.5-7.5 (for example, it can be 5.5, 6.0, 6.5, 7.0, 7.5).
[0025] Preferably, step (1) further includes a drying step after impregnation.
[0026] Preferably, the LDH precursor solution in step (2) is a metal salt solution containing aluminum ions, zinc ions, and magnesium ions.
[0027] Preferably, the molar ratio of aluminum ions, zinc ions, and magnesium ions in the LDH precursor solution is 1:(0.5-3):(0.5-3) (wherein, the specific value of 0.5-3 can be 0.5, 1, 1.5, 2, 2.5, 3, etc.).
[0028] Preferably, the mass ratio of the pretreated modified biochar to the solute in the LDH precursor solution in step (2) is 1:(1-3) (e.g., 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.).
[0029] Preferably, before mixing the LDH precursor solution with the pretreated modified biochar in step (2), the pH of the LDH precursor solution is adjusted to 8-11 (e.g., 8, 9, 10, 11, etc.).
[0030] Preferably, the mixing time in step (2) is 10-24 h (e.g., 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, etc.), and the temperature is 25-35℃ (e.g., 25℃, 27℃, 29℃, 31℃, 33℃, 35℃, etc.).
[0031] Preferably, the aging time in step (2) is 10-24 h (e.g., 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, etc.), and the temperature is 80-100℃ (e.g., 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃, 100℃, etc.).
[0032] Preferably, step (2) further includes filtration, washing, drying and sieving after aging.
[0033] Preferably, the mesh size of the sieve is 70-120 mesh (e.g., 70 mesh, 75 mesh, 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, 105 mesh, 110 mesh, 115 mesh, 120 mesh, etc.).
[0034] In a second aspect, the present invention provides a method for preparing a composite functional material as described in the first aspect, the method comprising: The composite functional material is obtained by mixing and sieving engineered biochar, zeolite, wollastonite, iron powder, and humic acid.
[0035] The method for preparing composite functional materials provided by this invention is simple, highly operable, has a wide range of raw material sources, and is highly adaptable to various applications.
[0036] Preferably, the mixing temperature is 15-25℃ (e.g., 15℃, 17℃, 19℃, 21℃, 23℃, 25℃, etc.).
[0037] Preferably, the mesh size of the sieve is 70-120 mesh (e.g., 70 mesh, 75 mesh, 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, 105 mesh, 110 mesh, 115 mesh, 120 mesh, etc.).
[0038] Thirdly, the present invention provides an application of the composite functional material as described in the first aspect in controlling soil carbon, nitrogen and phosphorus loss and reducing emissions.
[0039] Preferably, when the composite functional material is used to control the loss of carbon, nitrogen, and phosphorus in the soil and reduce emissions, the mass ratio of the composite functional material to the soil is (0.25-6):100 (e.g., 0.25:100, 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, 5.5:100, 6:100, etc.).
[0040] All other specific point values not listed above within the numerical ranges mentioned above can be selected and are all within the protection scope of this invention. For the sake of brevity, they will not be described in detail here.
[0041] Compared with the prior art, the present invention has the following beneficial effects: This invention creatively designs a composite functional material for synergistically controlling the loss of carbon, nitrogen, and phosphorus from soil. This composite functional material, through the synergistic effect of five materials—engineered biochar, zeolite, wollastonite, iron powder, and humic acid—can simultaneously and efficiently immobilize carbon, nitrogen, and phosphorus in the soil, effectively reducing their leaching and loss, thereby reducing non-point source pollution emissions from farmland and achieving highly efficient inhibition of carbon, nitrogen, and phosphorus nutrient loss. Compared to any single component, this composite material exhibits superior immobilization effects on soil carbon, nitrogen, and phosphorus; furthermore, the use of specific engineered biochar in this invention provides even more efficient immobilization of these nutrients. In addition, the composite functional material provided by this invention uses readily available raw materials, has strong application adaptability, and is inexpensive, making it widely applicable to the control of agricultural non-point source pollution. Detailed Implementation
[0042] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments of the present invention. However, the present invention is not limited to the scope of the embodiments.
[0043] The soil samples used in the application examples were all from cultivated land in northern China. Sampling depths ranged from 0 to 20 cm, and the soil was air-dried and passed through a 2 mm nylon sieve. The total nitrogen content of the soil was 1.07 g·kg⁻¹. -1 The total phosphorus content in the soil was 626.34 mg·kg⁻¹. -1 The available nitrogen content in the soil was 132.45 mg·kg⁻¹. -1 The available phosphorus content in the soil was 58.65 mg·kg⁻¹. -1 The pH value is 7.85.
[0044] Preparation Example 1 This preparation example provides an engineered biochar, prepared by the following method: (1) Mix agricultural waste biomass spirulina residue, soybean protein residue and bamboo chips (mass ratio of spirulina residue, soybean protein residue and bamboo chips is 0.5:0.5:1), pyrolyze at 800℃ for 2 h, then mix with iron salt mixed solution with a molar ratio of ferrous iron and ferric iron of 1:2 (mass ratio of agricultural waste biomass and iron salt used in iron salt solution is 2:1), adjust pH to 6.0, shake at 25℃ for 12 h on a magnetic stirrer, centrifuge, and then dry in a 90℃ oven for 12 h to obtain iron modified biochar FMBC; Prepare an LDH precursor solution consisting of 0.36 mol / L ZnCl2∙4H2O, 0.36 mol / L MgCl2∙6H2O, and 0.24 mol / L AlCl3∙6H2O. Adjust the pH of the LDH precursor solution to 10 and shake for 12 h. (2) Mix iron-modified biochar with LDH precursor solution (the mass ratio of solute in iron-modified biochar to LDH precursor solution is 1:2), stir with a magnetic stirrer for 12 h, and then age in an oven at 90℃ for 12 h. (3) After aging, the mixture was filtered and the resulting mud-like solid was washed three times with deionized water to make the pH of the washing solution 7.4. The final sample was placed in an oven to dry for 24 h, and then ground through a 100-mesh sieve to obtain engineered biochar FMLBC.
[0045] Preparation Example 2 This preparation example provides an engineered biochar, prepared by the following method: (1) Mix agricultural waste biomass spirulina residue, soybean protein residue and corn straw (the mass ratio of spirulina residue, soybean protein residue and corn straw is 1:1:1), pyrolyze at 600℃ for 1.5 h, then mix with iron salt mixed solution with a molar ratio of ferrous iron and ferric iron of 1:1.5 (the mass ratio of agricultural waste biomass and iron salt used in iron salt solution is 1:0.5), adjust the pH to 7.0, shake on a magnetic stirrer at 25℃ for 10 h, centrifuge, and then dry in a 90℃ oven for 10 h to obtain iron modified biochar FMBC; Prepare an LDH solution. The LDH precursor solution consists of 0.4 mol / L ZnCl2∙4H2O, 0.3 mol / L MgCl2∙6H2O and 0.2 mol / L AlCl3∙6H2O solutions. Adjust the pH of the LDH precursor solution to 9 and shake for 12 h. (2) Mix iron-modified biochar with LDH precursor solution (the mass ratio of solute in iron-modified biochar to LDH precursor solution is 1:1.5), stir with a magnetic stirrer for 12 h, and then age in an oven at 90℃ for 12 h. (3) After aging, the mixture was filtered and the resulting mud-like solid was washed three times with deionized water to make the pH of the washing solution 7.2. The final sample was placed in an oven to dry for 24 h, and then ground through a 90-mesh sieve to obtain engineered biochar FMLBC.
[0046] Preparation Example 3 This preparation example provides an engineered biochar, prepared by the following method: (1) Mix agricultural waste biomass spirulina residue, soybean protein residue and wheat crop straw (the mass ratio of spirulina residue, soybean protein residue and wheat crop straw is 1:2:1.5), pyrolyze at 500℃ for 2.5 h, then mix with iron salt mixed solution (the mass ratio of agricultural waste biomass and iron salt used in iron salt solution is 1:1.5), adjust the pH to 7.5, shake at 25℃ for 12 h on a magnetic stirrer, centrifuge, and then dry in a 90℃ oven for 10 h to obtain iron modified biochar FMBC; Prepare an LDH solution. The LDH precursor solution consists of 0.28 mol / L ZnCl2∙4H2O, 0.42 mol / L MgCl2∙6H2O and 0.28 mol / L AlCl3∙6H2O solutions. Adjust the pH of the LDH precursor solution to 10 and shake for 12 h. (2) Mix iron-modified biochar with LDH precursor solution (the mass ratio of solute in iron-modified biochar to LDH precursor solution is 1:2), stir with a magnetic stirrer for 12 h, and then age in an oven at 90℃ for 10 h. (3) After aging, the mixture was filtered and the resulting mud-like solid was washed three times with deionized water to make the pH of the washing solution 7.3. The final sample was placed in an oven to dry for 24 h, and then ground through an 80-mesh sieve to obtain engineered biochar FMLBC.
[0047] Preparation Example 4 This preparation example provides an engineered biochar. The difference between the preparation method and the preparation example 1 is that in step (1), spirulina residue is not used. Instead, soybean protein residue with a mass ratio of 1:1 is mixed with bamboo chips, while other conditions remain unchanged.
[0048] Preparation Example 5 This preparation example provides an engineered biochar. The difference between the preparation method and the preparation example 1 is that soybean protein residue is not used in step (1). Spirulina residue with a mass ratio of 1:1 is mixed with bamboo chips, and all other conditions remain unchanged.
[0049] Preparation Example 6 This preparation example provides an engineered biochar. The difference between the preparation method and that of Preparation Example 1 is that in step (1), spirulina residue, soybean protein residue, and bamboo chips are replaced with bamboo chips in equal amounts, while all other conditions remain unchanged.
[0050] Preparation Example 7 This preparation example provides an engineered biochar. The difference between the preparation method and the preparation example 1 is that in step (1), the spirulina residue, soybean protein residue, and bamboo shavings are replaced in equal amounts with a combination of bamboo shavings and corn straw in a mass ratio of 1:1, while all other conditions remain unchanged.
[0051] Preparation Example 8 This preparation example provides an engineered biochar. The difference between the preparation method and that of Preparation Example 1 is that in step (1), ZnCl2∙4H2O is not added to the LDH precursor solution, and the reduced portion of ZnCl2∙4H2O is allocated to MgCl2∙6H2O. All other conditions remain unchanged.
[0052] Preparation Example 9 This preparation example provides an engineered biochar. The difference between the preparation method and that of Preparation Example 1 is that in step (1), MgCl2∙6H2O is not added to the LDH precursor solution, and the reduced portion of MgCl2∙6H2O is allocated to ZnCl2∙4H2O. All other conditions remain unchanged.
[0053] Preparation Example 10 This preparation example provides an engineered biochar. The difference between the preparation method and Preparation Example 1 is that the LDH precursor solution in step (1) is composed of 0.36 mol / L CaCl2∙6H2O, 0.36 mol / L MgCl2∙6H2O and 0.24 mol / L AlCl3∙6H2O solutions, while other conditions remain unchanged.
[0054] Preparation Example 11 This preparation example provides a pyrolytic biochar, prepared by the following method: Agricultural waste biomass spirulina residue, soybean protein residue, and bamboo shavings were mixed (the mass ratio of spirulina residue, soybean protein residue, and bamboo shavings was 0.5:0.5:1) and pyrolyzed at 800℃ for 2 h to obtain pyrolytic biochar.
[0055] Example 1 This embodiment provides a composite functional material, which is obtained by the following preparation method: The engineered biochar obtained in Preparation Example 1 was mixed with zeolite, wollastonite, iron powder, and humic acid at a mass ratio of 2:1:1:1:1 at 25°C and passed through an 80-mesh sieve to obtain the composite functional material.
[0056] Example 2 This embodiment provides a composite functional material, which is obtained by the following preparation method: The engineered biochar obtained in Preparation Example 2 was mixed with zeolite, wollastonite, iron powder, and humic acid in a mass ratio of 1:1:1:2:1 at 20°C and passed through an 80-mesh sieve to obtain the composite functional material.
[0057] Example 3 This embodiment provides a composite functional material, which is obtained by the following preparation method: The engineered biochar obtained in Preparation Example 3 was mixed with zeolite, wollastonite, iron powder, and humic acid at a mass ratio of 2:1:1:1:1 at 25°C and passed through an 80-mesh sieve to obtain the composite functional material.
[0058] Example 4-11 Examples 4-11 each provide a composite functional material, the only difference from Example 1 is that the engineered biochar obtained in Preparation Example 1 is replaced with the engineered biochar or pyrolytic biochar obtained in Preparation Examples 4-11, while all other conditions remain unchanged.
[0059] Comparative Example 1 This comparative example provides a composite functional material, which differs from Example 1 only in that engineered biochar is not added, and the missing mass of engineered biochar is proportionally allocated to zeolite, wollastonite, iron powder, and humic acid, while other conditions remain unchanged.
[0060] Comparative Example 2 This comparative example provides a composite functional material, which differs from Example 1 only in that zeolite is not added, and the missing mass of zeolite is proportionally distributed to engineered biochar, wollastonite, iron powder, and humic acid, while other conditions remain unchanged.
[0061] Comparative Example 3 This comparative example provides a composite functional material, which differs from Example 1 only in that wollastonite is not added, and the missing mass of wollastonite is proportionally allocated to engineered biochar, zeolite, iron powder, and humic acid, while other conditions remain unchanged.
[0062] Comparative Example 4 This comparative example provides a composite functional material, which differs from Example 1 only in that iron powder is not added, and the missing mass of iron powder is proportionally distributed to engineered biochar, zeolite, wollastonite, and humic acid, while other conditions remain unchanged.
[0063] Comparative Example 5 This comparative example provides a composite functional material, which differs from Example 1 only in that humic acid is not added, and the missing mass of humic acid is proportionally distributed to engineered biochar, zeolite, wollastonite, and iron powder, while other conditions remain unchanged.
[0064] Comparative Example 6 This comparative example provides a composite functional material, which differs from Example 1 only in that zeolite and wollastonite are not added, and the missing mass of zeolite and wollastonite is proportionally allocated to engineered biochar, iron powder, and humic acid, while other conditions remain unchanged.
[0065] Application Example 1 This application example uses composite functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The specific procedure is as follows: Accurately weigh 30 g of the soil and place it in a 50 mL beaker. Then, apply the composite functional material from Example 1 to the soil at a mass ratio of 6:100, and thoroughly mix the composite functional material with the soil. All treatments were kept at 70% field capacity and placed in a constant temperature incubator for cultivation. Water was added using the constant weight method to maintain the water content at 70% of field capacity. When the cultivation reached 30 days, soil samples were collected to determine the contents of dissolved organic carbon (DOC), available phosphorus (AP), and alkaline nitrogen (AN).
[0066] The dissolved organic carbon was determined by ultraviolet spectrophotometry, the available phosphorus was determined by the molybdenum blue colorimetric method, and the alkaline nitrogen was determined by the alkaline distillation method.
[0067] The fixation efficiency of soil DOC, AP, and AN is calculated using the following formula (1). or (%)calculate: In the formula: C 0 and C a The DOC, AP, or AN contents (mg·kg) of blank soil samples and treated soil samples are respectively. -1 ).
[0068] Application Example 2-11 Application Example 2-11 uses composite functional materials to test the soil carbon, nitrogen and phosphorus fixation effect. The only difference between the test method and Application Example 1 is that the composite functional materials in Example 1 are replaced with the composite functional materials in Example 2-11 in equal amounts, while all other conditions remain unchanged.
[0069] Comparative Application Examples 1-6 Comparative Application Examples 1-6 used composite functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and Application Example 1 was that the composite functional materials in Example 1 were replaced with the composite functional materials in Comparative Examples 1-6 in equal amounts, while all other conditions remained unchanged.
[0070] Comparative Application Example 7 This comparative application example uses functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and application example 1 is that the composite functional material in example 1 is replaced with a single engineered biochar in equal amounts, while all other conditions remain unchanged.
[0071] Comparative Application Example 8 This comparative application example uses functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and application example 1 is that the composite functional material in example 1 is replaced with a single zeolite in equal amounts, while all other conditions remain unchanged.
[0072] Comparative Application Example 9 This comparative application example uses functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and application example 1 is that the composite functional material in example 1 is replaced with an equal amount of single wollastonite, while all other conditions remain unchanged.
[0073] Comparative Application Example 10 This comparative application example uses functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and application example 1 is that the composite functional material in example 1 is replaced with an equal amount of single iron powder, while all other conditions remain unchanged.
[0074] Comparative Application Example 11 This comparative application example uses functional materials to test the soil carbon, nitrogen, and phosphorus fixation effect. The only difference between the test method and application example 1 is that the composite functional material in example 1 is replaced with an equal amount of humic acid, while all other conditions remain unchanged.
[0075] Soil without any added functional materials was used as the blank control group (CK), and the blank control group and Application Example 1 underwent the same isothermal incubation process. The soil carbon, nitrogen, and phosphorus fixation effects of the blank control group, Application Examples 1-11, and control Application Examples 1-11 are shown in Table 1. The test results show that the composite functional material provided by this invention significantly improves the soil's carbon, nitrogen, and phosphorus fixation capacity. When the composite functional material is synthesized using five materials—engineered biochar, zeolite, wollastonite, iron powder, and humic acid—the five materials can achieve a synergistic effect. If any one of them is missing or only a single component is used for soil carbon, nitrogen, and phosphorus fixation, the effect will be significantly reduced, indicating that the five materials have an excellent synergistic effect.
[0076] The specific preparation method of engineered biochar designed in this invention can enable composite functional materials to have excellent soil carbon, nitrogen and phosphorus fixation effects. If the preparation conditions are changed, such as changing the compounding of core biomass, not adding core biomass, changing the composition of LDH precursor solution, or not modifying biochar, the soil carbon, nitrogen and phosphorus fixation effect of composite functional materials will decrease.
[0077] Test Example 1 This test case examines the impact of different dosages of composite functional materials on the reduction of soil carbon, nitrogen, and phosphorus nutrient loss.
[0078] A soil column leaching experiment was conducted using the composite functional material provided in Example 1 to study the loss of soil carbon, nitrogen, and phosphorus during the leaching process.
[0079] The tested soils were farmland soil and forest soil collected near Guanting Reservoir in Beijing. The sampling depth was 0-20 cm. After air drying, the soils were removed and passed through a 2 mm nylon sieve. The basic physical and chemical properties of the soils are shown in Table 2. Leaching experiments were conducted using an acrylic glass column with a diameter of 4 cm and a height of 30 cm. Before the experiment, a 5 cm high quartz sand filter layer was placed at the bottom of the leaching column to prevent soil collapse and ensure uniform water distribution. In the experiment, the composite functional material was thoroughly mixed with two types of soil at different mass ratios (1%, 3%, or 6%). The mixed soil was then added to the leaching column, filling it to a depth of 25 cm in all treatments. A blank control (CK) was used without the composite functional material. During the leaching experiment, a beaker was placed at the bottom of the column to collect the leachate. Distilled water was then used for leaching (120 mL per treatment per leaching), for a total of 7 leaching cycles. After the 7th leaching, the chemical oxygen demand (COD), total nitrogen, total phosphorus, and ammonium nitrogen content in the leachate were measured to analyze the permanganate index, COD, nitrogen, phosphorus, and ammonium nitrogen content, and to determine the control effect. After the experiment, soil samples were collected from the 0-10 cm and 10-20 cm soil layers, air-dried, and ground through a 2 mm nylon sieve to determine the content of dissolved organic carbon, available nitrogen, and available phosphorus in different soil layers.
[0080] The control efficiency η (%) of potassium permanganate, DOC, AP and AN in soil was calculated using formula (1).
[0081] The results are shown in Table 3. As shown in Table 3, the composite functional material has a strong inhibitory effect on carbon, nitrogen and phosphorus in both soil layers, whether it is the 0-10 cm soil layer or the 10-20 cm soil layer. Furthermore, the composite functional material's ability to fix DOC, AP and AN in both soil layers increases with the increase of the amount of composite material added. In addition, when the amount of composite functional material added is 6%wt, the inhibitory efficiency of the composite functional material on dissolved organic carbon, AP and AN can reach more than 60%.
[0082] Finally, based on the determination of permanganate index, chemical oxygen demand, total nitrogen, total phosphorus and ammonium nitrogen concentration in leachate, and combined with the results of the material's control of carbon, nitrogen and phosphorus in soil at different soil depths, the effect of the composite functional material on the control of carbon, nitrogen and phosphorus in the soil system was evaluated.
[0083] The test results are shown in Table 4. As shown in Table 4, the permanganate index, chemical oxygen demand (COD), total nitrogen, total phosphorus, and ammonium nitrogen in the leachate of the treated soil column after the application of the composite functional material all decreased significantly. Moreover, the decrease continued to increase with the increase of the amount of material added, indicating that the composite functional material has a very significant effect on reducing carbon, nitrogen, and phosphorus emissions in soil leachate. When the amount of material used is more than 3 wt%, the concentrations of COD, total phosphorus, and ammonium nitrogen in the corresponding treated soil leachate all decreased by more than 60%, while the reduction rate of total nitrogen also reached more than 40%, and the reduction rate of permanganate index was more than 85%. Under the treatment of the composite functional material in this invention, the water quality of soil leachate is greatly improved. With a dosage of 3%wt, the water quality of the leachate from the soil columns of the two experimental soils (arable land soil and forest soil) changed from Class V (poorest quality) to Class IV (poorest quality) in the initial untreated soil. In terms of COD, the water quality of the leachate changed from Class V (poorest quality) to Class I. As the dosage of the composite functional material increases, the effect of water quality improvement becomes more significant. Overall, the composite functional material has a good effect on the control of carbon, nitrogen and phosphorus. However, comparatively, the composite functional material has a slightly better effect on the control of carbon, phosphorus and ammonia nitrogen than on total nitrogen.
[0084] In summary, the composite functional material provided by this invention can synergistically and efficiently fix carbon, nitrogen, and phosphorus in the soil system, thereby simultaneously and effectively controlling the migration and loss of soil carbon, nitrogen, and phosphorus. This helps to reduce the loss of soil carbon, nitrogen, and phosphorus elements through runoff or leaching, ultimately effectively alleviating agricultural non-point source pollution. Furthermore, the composite functional material provided by this invention uses readily available raw materials, has a simple preparation method, strong application adaptability, and is inexpensive, making it widely applicable in the field of agricultural non-point source pollution control.
[0085] The applicant declares that the technical solution of this invention is illustrated by the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.
[0086] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
Claims
1. A composite functional material that synergistically inhibits the loss of carbon, nitrogen, and phosphorus from soil, characterized in that, The components of the composite functional material include: engineered biochar, zeolite, wollastonite, iron powder, and humic acid. The mass ratio of the engineered biochar, zeolite, wollastonite, iron powder, and humic acid is (0.5-3):(0.5-2):(0.5-2):(0.5-2):
1. The engineered biochar was obtained by the following preparation method: (1) After pyrolyzing agricultural waste biomass, it is mixed with iron salt solution for impregnation, and the pH of the solution is adjusted to obtain pretreated modified biochar; (2) The pretreated modified biochar was mixed with the LDH precursor solution and aged to obtain engineered biochar.
2. The composite functional material according to claim 1, characterized in that, The agricultural waste biomass mentioned in step (1) includes core biomass and basic biomass; The basic biomass is selected from any one or a combination of at least two of bamboo shavings, rice, corn stalks, and wheat crop stalks; The core biomass is a combination of spirulina residue and soybean protein residue in a mass ratio of 1:(0.5-3); The mass ratio of the core biomass to the basic biomass is 1:(0.5-2).
3. The composite functional material according to claim 1, characterized in that, The pyrolysis in step (1) is performed at a temperature of 400-800℃ for 1.5-2.5 h. The soaking time in step (1) is 10-24 h, and the temperature is 25-35℃.
4. The composite functional material according to claim 1, characterized in that, The iron salt solution in step (1) comprises a mixed solution of ferrous and ferric iron in a molar ratio of 1:(1-3); In step (1), the mass ratio of agricultural waste biomass to iron salt used in the iron salt solution is 1:(0.5-3). The pH value of the solution is adjusted to 5.5-7.5 in step (1).
5. The composite functional material according to claim 1, characterized in that, The LDH precursor solution in step (2) is a metal salt solution of aluminum ions, zinc ions, and magnesium ions in a molar ratio of 1:(0.5-3):(0.5-3); In step (2), the mass ratio of the pretreated modified biochar to the solute in the LDH precursor solution is 1:(1-3). Before mixing the LDH precursor solution with the pretreated modified biochar in step (2), the pH of the LDH precursor solution is adjusted to 8-11.
6. The composite functional material according to claim 1, characterized in that, The mixing time in step (2) is 10-24 hours, and the temperature is 25-35℃; The aging time in step (2) is 10-24 h, and the temperature is 80-100℃.
7. The method for preparing the composite functional material according to any one of claims 1-6, characterized in that, The preparation method includes: The composite functional material is obtained by mixing and sieving engineered biochar, zeolite, wollastonite, iron powder, and humic acid.
8. The preparation method according to claim 7, characterized in that, The mixing temperature is 15-25℃.
9. The application of the composite functional material according to any one of claims 1-6 in soil carbon, nitrogen and phosphorus fixation.
10. The application according to claim 9, characterized in that, When the composite functional material is used for soil carbon, nitrogen and phosphorus fixation, the mass ratio of the composite functional material to the soil is (0.25-6):100.