Multifunctional soil conditioner as well as preparation method and application thereof

Abstract

The invention provides a multifunctional soil conditioner as well as a preparation method and application thereof, and relates to the technical field of soil conditioning. Comprising 5-15 parts of nano cellulose modified by a phosphorus-containing compound; 15 to 25 parts of zinc-aluminum hydrotalcite; 25 to 35 parts of magnetic nano montmorillonite; 30 to 40 parts of attapulgite; 5-15 parts of an amino acid mixture; the phosphorus-containing compound modified nano-crystalline cellulose is prepared by the following steps: dispersing nano-crystalline cellulose in deionized water to prepare a nano-crystalline cellulose suspension; and then adding a phosphorus-containing compound into the nano-cellulose suspension for modification, the magnetic nano montmorillonite is prepared by dispersing montmorillonite in an aqueous solution containing ferroferric oxide nano particles and carrying out ultrasonic stirring modification; the amino acid mixture is a mixture of glycine, alanine and lysine. The soil conditioner has multiple effects of adjusting the pH value of soil, reducing the content of various heavy metal pollutants in the soil, increasing the crop yield and the like, secondary pollution is avoided, and the effect is stable.

Description

Technical Field

[0001] The invention relates to the technical field of soil conditioning, and in particular to a multifunctional soil conditioner and a preparation method and application thereof. Background Art

[0002] With the development of industrialization and agricultural modernization, soil pollution is becoming increasingly serious. Among them, the combined pollution of heavy metals such as cadmium, mercury, and arsenic poses a huge threat to soil quality and crop safety. At the same time, soil acidification is also relatively common, resulting in a decrease in soil fertility and affecting crop growth. Traditional soil conditioners often have high process costs and single functions, making it difficult to solve multiple soil problems at the same time. In addition, traditional soil conditioners may cause secondary pollution to the soil during use, or their effects are difficult to last.

[0003] For example, Chinese patent document CN109053961A discloses a heavy metal ion repair material for soil remediation and a preparation method thereof. The heavy metal ion repair material for soil remediation agent is composed of acrylic acid, phosphoric acid-modified acrylic acid, mercaptoethylamine-modified acrylic acid, modified nanocellulose, acrylamide, water, cyclohexane, ammonium persulfate, Sr-10 emulsifier, Tween 80, methyl methacrylate and N,N'-methylenebisacrylamide. The soil remediation agent has excellent performance in repairing soil heavy metal ions, but its process is complicated, and highly corrosive materials such as concentrated sulfuric acid and concentrated nitric acid are used in the components, the reaction conditions are high, the cost is high, and it is easy to cause adverse effects on the environment.

[0004] Chinese patent document CN110773119A discloses a multivalent coexisting iron-based pillared montmorillonite and its preparation method and application, which uses calcium-based nano-montmorillonite as raw material and iron salt solution as pillaring agent, and prepares iron-based pillared nano-montmorillonite by mixing, aging, reducing and calcining. The multivalent coexisting iron-based pillared nano-montmorillonite prepared by the invention is simple, and contains zero-valent iron and iron oxide at the same time. The zero-valent iron with a particle size of 2 to 10 nm accounts for more than 90% of the total amount, which can be used as a carrier for biofilm growth, and is used for degradation materials of polycyclic aromatic hydrocarbons in soil and adsorption materials of heavy metal ions. However, the growth of the biofilm may affect the adsorption of heavy metals, and the stability of the zero-valent iron and iron oxide is poor.

[0005] Therefore, it is of great practical significance to develop a multifunctional soil conditioner that can simultaneously reduce the content of cadmium, mercury, and arsenic in the soil, increase the soil pH, and effectively increase crop yields with stable effects. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a multifunctional soil conditioner and its preparation method and application. The soil conditioner provided by the present invention has multiple functions such as adjusting soil pH, reducing the content of various heavy metal pollutants such as cadmium, arsenic, mercury in the soil, and increasing crop yields, without secondary pollution, and can solve the multiple problems of existing soil conditioners such as single product function, high cost, and unstable effect.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a multifunctional soil conditioner, which is prepared from the following raw materials in parts by weight:

[0009] Nanocellulose modified with phosphorus-containing compounds: 5-15 parts;

[0010] Zinc-aluminum hydrotalcite: 15-25 parts;

[0011] Magnetic nano-montmorillonite: 25-35 parts;

[0012] Attapulgite: 30-40 parts;

[0013] Amino acid mixture: 5-15 parts;

[0014] Wherein: the nanocellulose modified by the phosphorus-containing compound is prepared by the following method: taking nanocellulose, dispersing it in deionized water, and preparing a nanocellulose suspension with a mass concentration of 1% to 5%; then adding the phosphorus-containing compound to the nanocellulose suspension, and the mass ratio of the phosphorus-containing compound to the nanocellulose is 1:3; after fully stirring the reaction, centrifuging the reaction solution, washing the separated precipitate, and drying it to a constant weight, the nanocellulose is obtained;

[0015] The magnetic nano-montmorillonite is prepared by dispersing montmorillonite in an aqueous solution containing ferroferric oxide nanoparticles and then modifying it by ultrasonic stirring.

[0016] The amino acid mixture is a mixture of glycine, alanine and lysine.

[0017] Furthermore, the phosphorus-containing compound is diammonium hydrogen phosphate, potassium dihydrogen phosphate, etc.

[0018] Furthermore, the conditions for the stirring reaction of the phosphorus-containing compound and the nanocellulose are: stirring the reaction at a temperature of 30-60° C. and a rotation speed of 200-500 r / min for 2-6 hours.

[0019] Furthermore, in the method for preparing nanocellulose modified by phosphorus-containing compounds, the conditions for centrifugal separation of the reaction liquid after the reaction are 3000-5000 r / min for 10-20 minutes; and the drying temperature is 40-60°C.

[0020] Furthermore, the zinc-aluminum hydrotalcite is prepared by the following method: dissolving zinc salt, aluminum salt and deionized water in a molar ratio of zinc element, aluminum element and water of 1:1:22, adding alkaline solution to adjust the pH to 10±0.1, stirring the reaction for 2 hours and then standing to precipitate, washing with deionized water, and drying at a temperature of 80~100°C to obtain zinc-aluminum hydrotalcite.

[0021] Preferably, the zinc salt is any one of zinc nitrate, zinc chloride, zinc sulfate and zinc acetate.

[0022] Preferably, the aluminum salt is any one of aluminum nitrate, aluminum chloride, aluminum sulfate and aluminum acetate.

[0023] Preferably, the alkaline solution is one or a mixture of two or more of NaOH, Na2CO3, ammonia water, KOH or urea.

[0024] Furthermore, the preparation method of the magnetic nano-montmorillonite is as follows: montmorillonite is dispersed in an aqueous solution containing ferroferric oxide nanoparticles, wherein the mass ratio of montmorillonite to nano-ferroferric oxide is 1:1 or 2:1; then, under the action of ultrasound, stirring is performed simultaneously so that the ferroferric oxide nanoparticles are fully adsorbed on the surface of the montmorillonite, and the conditions for ultrasonic stirring modification are: maintaining the ultrasonic power at 300-400W, and controlling the speed to be 300-500r / min for stirring for 1-2 hours; then centrifuging and precipitating, washing the precipitate, and vacuum drying to obtain the nano-magnetic montmorillonite.

[0025] Furthermore, in the preparation method of magnetic nano-montmorillonite, the centrifugal precipitation condition is: centrifugation at a speed of 5000-8000 r / min for 10-20 min.

[0026] Furthermore, in the preparation method of magnetic nano-montmorillonite, the vacuum drying conditions are: drying at 60-80° C. for 12-24 hours under a vacuum degree of -0.08-0.1 MPa.

[0027] Furthermore, the weight ratio of glycine, alanine and lysine in the amino acid mixture is (1-2):1:1.

[0028] In a second aspect, the present invention further provides a method for preparing the multifunctional soil conditioner, which specifically comprises the following steps:

[0029] The raw materials are weighed according to the weight parts, and then the nanocellulose modified with phosphorus compounds, zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, attapulgite and amino acid mixture are fully stirred and mixed evenly, and then dried at 50-60° C. for 2-3 hours to obtain the multifunctional soil conditioner.

[0030] Furthermore, the stirring and mixing conditions are: stirring at a rotation speed of 200 to 300 rpm for 30 to 60 minutes.

[0031] In a third aspect, the present invention provides an application of the multifunctional soil conditioner or the multifunctional soil conditioner prepared by the above method in soil conditioning and restoration, specifically, 7 to 15 days before rice transplanting, the soil conditioner is spread at a rate of 75 to 100 kg / mu, and the soil is plowed after spreading with a plowing depth of 15 to 20 cm to fully mix the soil and the conditioner.

[0032] The mechanism of action of each component in the present invention is as follows:

[0033] 1. Nanocellulose modified with phosphorus-containing compounds: The phosphorus-containing groups in the nanocellulose modified with phosphorus-containing compounds provided by the present invention can react chemically with cadmium, mercury, and arsenic ions to generate insoluble phosphate precipitates, such as cadmium phosphate precipitates formed with cadmium ions, thereby reducing the mobility and bioavailability of heavy metal ions. Nanocellulose has a large specific surface area and abundant hydroxyl groups, and can fix cadmium, mercury, and arsenic ions on its surface through physical adsorption and the complexation of hydroxyl groups with heavy metal ions. When phosphorus-containing compounds undergo hydrolysis in the soil, hydroxide ions may be generated to neutralize acidic substances in the soil, thereby increasing the pH value of the soil.

[0034] 2. Zinc-aluminum hydrotalcite: The zinc-aluminum hydrotalcite provided by the present invention has a layered structure and a large specific surface area. Its surface carries a negative charge and can adsorb positively charged cadmium, mercury, and arsenic ions on its surface through electrostatic adsorption, thereby reducing the effective content of heavy metals.

[0035] 3. Magnetic nano-montmorillonite: The ferroferric oxide nanoparticles in the magnetic nano-montmorillonite component provided by the present invention are fully adsorbed on the surface of montmorillonite. It has a huge specific surface area and abundant surface active sites. It can efficiently adsorb cadmium, mercury and arsenic ions through electrostatic adsorption, ion exchange and coordination complexation, and has strong stability.

[0036] 4. Attapulgite: Some functional groups (such as hydroxyl groups) on the surface of the attapulgite component of the present invention can react with heavy metal ions to enhance the fixation of heavy metal ions. At the same time, it can improve the soil structure, increase the looseness and aeration of the soil, promote the growth and development of crop roots, and improve the crop's ability to absorb nutrients and water.

[0037] 5. Amino acid mixture: The amino acids provided by the present invention are composed of glycine, alanine, lysine and other amino acids. The amino group, carboxyl group and other functional groups in the amino acid molecules can react with cadmium, mercury and arsenic ions to form stable complexes, thereby reducing the activity and bioavailability of heavy metal ions. In addition, the amino acid mixture can be used as a nutrient such as an organic nitrogen source, participate in the protein synthesis and other metabolic processes of crops, and promote the growth and development of crops.

[0038] The present invention has the following beneficial effects:

[0039] 1. Collaboration of multiple types of materials. The soil conditioner provided by the present invention integrates organic polymer materials (nanocellulose modified with phosphorus compounds), inorganic mineral materials (zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, attapulgite) and organic nutrients (amino acid mixture). Compared with traditional soil conditioners that have a single ingredient, or only focus on improving the physical structure of the soil, or are mainly used to adjust the pH of the soil, the various ingredients of the soil conditioner provided by the present invention cooperate with each other, and can comprehensively improve the soil from multiple angles, achieving the multiple functions of adjusting soil acidity, reducing heavy metal concentrations, improving soil structure, and increasing crop yields.

[0040] 2. High efficiency and stability. The nanocellulose and magnetic nano-montmorillonite modified with phosphorus-containing compounds in the soil conditioner provided by the present invention belong to the category of nanomaterials, and the nanocellulose is modified with phosphorus-containing compounds. Nanomaterials and modified nanomaterials have unique small size effects, surface effects and quantum size effects, which make them have larger specific surface areas and higher reactivity than traditional materials. And the nanocellulose and nano-montmorillonite modified with phosphorus-containing compounds have faster, stronger and more stable adsorption of heavy metals compared to nanocellulose and montmorillonite that are not modified or are not nanomaterials.

[0041] 3. No secondary pollution. The raw materials of the soil conditioner provided by the present invention are mostly natural minerals (such as zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, attapulgite) and biodegradable materials (such as nanocellulose modified by phosphorus compounds, amino acid mixtures), which are environmentally friendly and will not cause secondary pollution. Compared with some products containing chemical synthetic substances, it is more in line with the requirements of sustainable agricultural development and is conducive to long-term improvement of soil quality and ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic flow chart of a method for preparing a multifunctional soil conditioner provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0044] As used herein:

[0045] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0046] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0047] When a parameter is expressed as a range, a preferred range, or a range limited by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges of "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0048] In these examples, parts and percentages are by mass unless otherwise indicated.

[0049] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Preferred embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0050] 1. Preparation of multifunctional soil conditioner

[0051] like Figure 1As shown, the present invention provides a multifunctional soil conditioner, the main components of which include 5-15 parts of nanocellulose modified with phosphorus compounds, 15-25 parts of zinc-aluminum hydrotalcite, 25-35 parts of magnetic nano-montmorillonite, 30-40 parts of attapulgite, and 5-15 parts of an amino acid mixture. Among them:

[0052] Nanocellulose modified with phosphorus-containing compounds is prepared by the following method: nanocellulose is taken, dispersed in deionized water, and prepared into a nanocellulose suspension with a mass concentration of 1% to 5%. A phosphorus-containing compound, such as diammonium hydrogen phosphate, potassium dihydrogen phosphate, etc., is added to the above suspension to control the mass ratio of the phosphorus-containing compound to the nanocellulose. Too high or too low a mass ratio may lead to overreaction or excessive phosphorus-containing compound residue. In the scheme of the present invention, the mass ratio of the phosphorus-containing compound to the nanocellulose is controlled to be 1:3. At a temperature of 30 to 60°C, the reaction is stirred at a speed of 200 to 500 r / min for 2 to 6 hours. After the reaction is completed, the mixed solution is centrifuged at a centrifugal speed of 3000 to 5000 r / min for 10 to 20 minutes. The precipitate is washed 3 to 5 times with deionized water, and then dried to constant weight at a temperature of 40 to 60°C.

[0053] The zinc-aluminum hydrotalcite is prepared by the following method: dissolving a zinc-containing salt, an aluminum-containing salt, and deionized water according to a preset molar ratio of zinc element, aluminum element, and water, adding an alkaline solution to adjust the pH to 10±0.1, stirring the reaction for 2 hours, and then standing to precipitate, washing with deionized water, and drying at a temperature of 80~100°C to obtain the zinc-aluminum hydrotalcite. In a specific embodiment, the zinc-containing salt is any one of zinc nitrate, zinc chloride, zinc sulfate, and zinc acetate; the aluminum-containing salt is any one of aluminum nitrate, aluminum chloride, aluminum sulfate, and aluminum acetate; and the alkaline solution is one or a mixture of two or more of NaOH, Na2CO3, ammonia, KOH, or urea. Insufficient deionized water in the preparation process of zinc-aluminum hydrotalcite will result in the inability to completely dissolve the zinc-containing salt and the aluminum-containing salt, which will lead to uneven reaction and impurity generation. Therefore, the amount of deionized water in the method should ensure that the zinc-containing salt and the aluminum-containing salt can be completely dissolved, and the molar ratio of zinc element, aluminum element, and water is preferably 1:1:22.

[0054] The magnetic nano-montmorillonite is prepared by the following method: montmorillonite is dispersed in an aqueous solution containing nano-ferroferric oxide particles, wherein the mass ratio of montmorillonite to nano-ferroferric oxide is 1:1 or 2:1, preferably 1:1, and the magnetic properties of montmorillonite can be significantly improved at this ratio. Ultrasonication is performed under the effect of ultrasonic power maintained at 300-400W, and the speed is controlled at 300-500r / min and stirred for 1-2 hours, so that the nano-ferroferric oxide particles are fully adsorbed on the surface of montmorillonite. The mixed solution after ultrasonic stirring is transferred to a centrifuge tube, placed in a centrifuge, and centrifuged at a speed of 5000-8000r / min for 10-20min to precipitate the magnetic nano-montmorillonite. The precipitate is washed with deionized water for 3-5 times, and the washed magnetic nano-montmorillonite is precipitated in a vacuum drying oven at a temperature of 60-80°C and a vacuum degree of -0.08--0.1MPa for 12-24 hours to obtain nano-magnetic montmorillonite.

[0055] Attapulgite: Crush and sieve the attapulgite to remove impurities and set aside for later use or purchase directly.

[0056] The amino acid mixture is prepared by mixing glycine, alanine and lysine in a weight ratio of (1-2):1:1, and the weight ratio is preferably 1:1:1 or 2:1:1.

[0057] Finally, the obtained raw materials are weighed according to the weight parts, stirred at a speed of 200-300 rpm for 30-60 minutes to fully stir and mix, and then dried at 50-60° C. for 2-3 hours to obtain the multifunctional soil conditioner.

[0058] The present invention is described by the following specific examples. If no specific conditions are specified in the following specific embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0059] 1. The nanocellulose modified with the phosphorus-containing compound in the following experimental groups was prepared by the following method: nanocellulose was taken, dispersed in deionized water, and prepared into a nanocellulose suspension with a mass concentration of 6%. The phosphorus-containing compound potassium dihydrogen phosphate was added to the above suspension, and the mass ratio of potassium dihydrogen phosphate to nanocellulose was 1:3. The reaction was stirred at a speed of 500r / min at a temperature of 60°C for 6 hours. After the reaction was completed, the mixed solution was centrifuged at a centrifugal speed of 5000r / min for 20 minutes. The precipitate was washed 5 times with deionized water, and then dried to constant weight at a temperature of 60°C to obtain nanocellulose modified with the phosphorus-containing compound.

[0060] Among them, nanocellulose was purchased from Shanghai McLean Biological Reagents, with a diameter of 4-10 nm, a length of 200 nm, and a 6% dispersion. Potassium dihydrogen phosphate was purchased from Shandong Borui Chemical Co., Ltd., with a molecular formula of KH2PO4.

[0061] 2. The zinc-aluminum hydrotalcite in the following experimental groups was prepared by the following method: zinc nitrate, aluminum nitrate and deionized water were dissolved in a mass ratio of 1:1:22, sodium hydroxide solution was added to adjust the pH to 10, the mixture was stirred for reaction for 2 hours and then allowed to stand for precipitation, the mixture was washed three times with deionized water, and the mixture was dried at 80°C to obtain zinc-aluminum hydrotalcite.

[0062] Among them, zinc nitrate: purchased from Xiaxian Yunli Chemical Co., Ltd., with a molecular formula of Zn(NO3)2·6H2O, a relative density of 2.065, and a melting point of 36.4°C. Aluminum nitrate: purchased from Langfang Yaocai Fine Chemical Co., Ltd., with a molecular formula of AI(NO3)3·6H2O, a relative density of 1.72, and a melting point of 73.5°C.

[0063] 3. The magnetic nano-montmorillonite in each of the following experimental groups was prepared by the following method: montmorillonite was dispersed in a solution containing nano-iron tetroxide particles, wherein the mass ratio of montmorillonite to nano-iron tetroxide was 1:1. Ultrasonication was performed at an ultrasonic power of 400W, and the speed was controlled at 500r / min for 2 hours to allow the nano-iron tetroxide particles to be fully adsorbed on the surface of montmorillonite. The mixed solution after ultrasonic stirring was transferred to a centrifuge tube, placed in a centrifuge, and centrifuged at 8000r / min for 20 minutes to precipitate the magnetic nano-montmorillonite. The precipitate was washed with deionized water 5 times, and the washed magnetic nano-montmorillonite was precipitated in a vacuum drying oven at a temperature of 80°C and a vacuum degree of -0.1MPa for 12 hours to obtain nano-magnetic montmorillonite.

[0064] Among them, nano-ferroferric oxide: purchased from Luoyang Tongrun Information Technology Co., Ltd., spherical 100~200nm, 99% purity. Montmorillonite: purchased from Hunan Hongcheng Ore Powder Co., Ltd., density 2.6g / cm³, viscosity 70mPa·s.

[0065] 4. The attapulgite in the following experimental groups was purchased from Hunan Hongcheng Ore Powder Co., Ltd., with off-white color and 200 mesh.

[0066] 5. The amino acid mixtures in the following experimental groups were prepared by the following method: glycine, alanine, and lysine were mixed in a weight ratio of 2:1:1. Among them, glycine, alanine, and lysine were purchased from Anhui Weimao Biotechnology Co., Ltd., and the effective substance content was ≥99%.

[0067] The weight compositions of the main components in each group of embodiments and comparative examples are shown in Tables 1 to 3 below. The raw materials are weighed according to the proportions of each group in Tables 1 to 3, stirred at a speed of 250 rpm for 50 minutes to fully mix, and then dried at 60° C. for 2 hours to obtain soil conditioners of each group (respectively referred to as Embodiment 1, Embodiment 2, Embodiment 3, Comparative Example 1, and Comparative Example 2).

[0068]

[0069]

[0070]

[0071] In order to verify whether there is any difference in treatment effect and stability when the nanocellulose in the soil conditioner is not modified with phosphorus-containing compounds and the montmorillonite is not magnetic nano-montmorillonite, the control groups shown in Tables 2 and 3 were set up. The nanocellulose in Table 2 uses the unmodified nanocellulose from the same source as in Table 1, and the montmorillonite in Table 3 uses the unmodified montmorillonite from the same source as in Table 1.

[0072] 2. Soil Conditioner Soil Cultivation Test

[0073] The following tests were conducted for soil pH, available cadmium, available mercury, and available arsenic, rice yield, rice cadmium, rice mercury, and rice arsenic content as follows:

[0074] (1) Soil pH determination method: Use water as the extractant, collect a small amount of soil and mix the water and soil in a mass ratio of 2.5:1, and then measure it using the potentiometric method (refer to NY / T1377-2007).

[0075] (2) Determination method of soil aggregate mean weight diameter (WMD): .

[0076] B i is the average diameter of aggregates in any size range screened out, W i It is the fraction of the corresponding mass of aggregates in any size range to the dry mass of the soil sample. The larger the MWD value, the higher the stability of soil aggregates and the better the soil structure.

[0077] (2) Determination of available cadmium in soil: refer to “Determination of Available Lead and Cadmium in Soil Quality—Atomic Absorption Method” (GB / T23739-2009).

[0078] (4) Determination of available mercury and available arsenic in soil: refer to "Determination of Available Arsenic and Available Mercury in Acidic Soil by Atomic Fluorescence Method" (DB35 / T 1459-2014).

[0079] (5) Rice yield determination: refer to "Rice Yield Determination Operation Specification" (DB33 / T 2517-2022).

[0080] (6) Method for determination of cadmium in rice: refer to the National Food Safety Standard - Determination of Cadmium in Food (GB 5009.15-2023).

[0081] (7) Method for determination of mercury in rice: refer to the National Food Safety Standard - Determination of Total Mercury and Organic Mercury in Food (GB5009.17-2014).

[0082] (8) Method for determination of arsenic in rice: refer to the National Food Safety Standard - Determination of Total Arsenic and Inorganic Arsenic in Foods (GB5009.11-2024).

[0083] 1. Soil culture test

[0084] The soil contaminated by cadmium, arsenic and mercury was collected from the vicinity of an industrial zone in Hengyang for indoor soil culture test. The pH of the test soil was 5.82, with total cadmium of 2.81 mg / kg, total arsenic of 162 mg / kg, total mercury of 3.57 mg / kg, effective cadmium of 0.89 mg / kg, effective mercury of 0.19 mg / kg, and effective arsenic of 17.3 mg / kg.

[0085] Set up 6 processes:

[0086] Treatment 1 (control): no material was applied;

[0087] Treatment 2: Apply the soil conditioner prepared in Example 1 at a dosage of 5 g / bottle;

[0088] Treatment 3: Apply the soil conditioner prepared in Example 2 at a dosage of 5 g / bottle;

[0089] Treatment 4: Apply the soil conditioner prepared in Example 3 at a dosage of 5 g / bottle;

[0090] Treatment 5: The soil conditioner prepared in Comparative Example 1 was applied at a dosage of 5 g / bottle;

[0091] Treatment 6: The soil conditioner prepared in Comparative Example 2 was applied at a dosage of 5 g / bottle.

[0092] Each treatment was replicated three times. For each replicate, 7.5 kg of soil was placed in a plastic culture bottle, and the corresponding materials were added and mixed evenly, and the soil moisture was maintained at 60% to 80% of the field water holding capacity.

[0093] The plastic culture bottle containing soil was placed in a constant temperature incubator, and the culture temperature was controlled at about 25°C. After 7d, 14d, 28d, 56d, and 63d (d represents days), appropriate amount of soil samples (about 10g) were taken from each replicate of each treatment group, and the samples were sampled by quartering method. After air drying, grinding, and passing through a 0.149mm sieve, the heavy metal content was determined. The determination method was the same as that of the initial soil sample.

[0094] The changes in soil cadmium, mercury and arsenic content under different treatments and different time periods are shown in the following table.

[0095]

[0096]

[0097]

[0098] As can be seen from Tables 4 to 6, relative to the control group, the contents of soil effective cadmium, effective mercury, and effective arsenic in both the embodiment and the comparative example were reduced to a certain extent over time. However, the embodiment decreased faster than the comparative example, and the amplitude was higher than that in the comparative example, especially at 7 days. At 56 days, the contents of soil heavy metals such as cadmium, mercury, and arsenic in the embodiment were basically stable, but some of the comparative examples showed a rebound phenomenon, indicating that the performance stability of the soil conditioner provided in the comparative example is not as good as that of the soil conditioner provided in the embodiment of the present invention.

[0099] 2. Rice Community Experiment

[0100] A rice plot experiment was conducted in a rice field with Cd, Hg, and As complex pollution near an industrial park in Hengyang. The test soil pH was 5.85, total cadmium was 2.45 mg / kg, total mercury was 3.42 mg / kg, total arsenic was 146 mg / kg, effective cadmium was 0.73 mg / kg, effective mercury was 0.17 mg / kg, and effective arsenic was 18.5 mg / kg. The rice variety was Zhuliangyou 505, purchased from Hunan Yahua Seed Co., Ltd. The experiment set up 6 treatments: each treatment was repeated 3 times, with a total of 18 plots, arranged in random blocks. The plot size was 4m×8m (32m 2 ), separated by ridges 30cm high and 30cm wide, covered with agricultural film, and irrigated in separate rows in each plot to prevent water and fertilizer from mixing with each other.

[0101] The 6 treatments are as follows:

[0102] Treatment 1: Blank (CK), conventional fertilization without any conditioner.

[0103] Treatment 2: conventional fertilization + 100 kg / mu of soil conditioner prepared in Example 1.

[0104] Treatment 3: conventional fertilization + 100 kg / mu of soil conditioner prepared in Example 2.

[0105] Treatment 4: conventional fertilization + soil conditioner prepared in Example 3 at 100 kg / mu.

[0106] Treatment 5: conventional fertilization + 100 kg / mu of soil conditioner prepared in Comparative Example 1.

[0107] Treatment 6: conventional fertilization + soil conditioner prepared in Comparative Example 2 at 100 kg / mu.

[0108] On the basis of conventional fertilization, the conditioner is evenly spread on the field surface by manual or mechanical spreading 7 days before plowing, and the conditioner is evenly mixed with the soil by rotary tiller. The appropriate amount of water is poured to stabilize and mature for 3 days before rice transplanting. During the rice growth period, weeding, fertilization, pesticide spraying and irrigation are carried out according to local production management methods.

[0109] When the rice is mature, collect 1.5 kg of soil samples, air-dry them naturally, grind them, and pass them through a 20-mesh sieve (for pH value) and a 100-mesh sieve (for analyzing the total cadmium, total mercury, and total arsenic content in the soil). Mix them evenly, and put them into sealed bags according to their numbers for storage.

[0110] 1.5 kg of rice sample was collected, and the rice was husked by a husker to obtain rice, dried and ground, passed through an 80-mesh sieve to remove impurities and particles, and put into a sealed bag for storage.

[0111] 2.1 Effects of different treatments on soil pH and soil aggregate diameter

[0112] After testing, the test results of the effects of different treatment groups on soil physical and chemical properties are shown in Table 7:

[0113] As can be seen from Table 7, the soil pH value of treatment 1 (CK) was 5.85 and the average weight diameter (WMD) of soil aggregates was 0.9 mm. Compared with treatment 1, treatments 2, 3, 4, 5, and 6 all increased the soil pH value and soil WMD to a certain extent.

[0114] Among them, the soil pH value improvement rates were 5.13%, 4.62%, 3.93%, 4.44% and 4.79% respectively, and the improvement effect was treatment 2>treatment 6>treatment 3>treatment 5>treatment 4.

[0115] The soil WMD value improvement rates were 333%, 322%, 300%, 256%, and 267%, respectively, and the improvement effect was treatment 2>treatment 3>treatment 4>treatment 6>treatment 5. The larger the MWD value, the higher the stability of soil aggregates and the better the soil structure.

[0116] 2.2 Effects of different treatments on soil available cadmium, available mercury and available arsenic contents

[0117] After testing, the results of the effects of different treatment groups on the available cadmium and available arsenic content in the soil are shown in Table 8:

[0118] As can be seen from Table 8, the effective cadmium content in the soil of Treatment 1 (CK) was 0.73 mg / kg, the effective mercury content was 0.17 mg / kg, and the effective arsenic content in the soil was 18.5 mg / kg. Compared with Treatment 1, Treatments 2, 3, 4, 5, and 6 all reduced the effective cadmium, effective mercury, and effective arsenic contents in the soil to a certain extent.

[0119] Among them, the reduction rates of soil available cadmium were 57.5%, 53.4%, 50.7%, 39.7% and 42.4% respectively, and the reduction effect was treatment 2 > treatment 3 > treatment 4 > treatment 6 > treatment 5.

[0120] The reduction rates of soil available mercury were 52.9%, 47.1%, 41.2%, 29.4% and 35.3% respectively, and the reduction effect was treatment 2 > treatment 3 > treatment 4 > treatment 6 > treatment 5.

[0121] The reduction rates of effective arsenic content were 60.5%, 58.4%, 57.3%, 41.1% and 37.8% respectively, and the reduction effect was treatment 2 > treatment 3 > treatment 4 > treatment 5 > treatment 6.

[0122] 2.3 Effects of different treatments on rice yield

[0123] After testing, the results of the experiment on the effect of different treatment groups on rice yield are shown in Table 9:

[0124] As can be seen from Table 9, the rice yield of Treatment 1 (CK) was 504.5 kg / mu. Compared with Treatment 1, Treatments 2, 3, 4, 5, and 6 all increased the rice yield to a certain extent, with the increase being 6.3%, 5.5%, 5.4%, 4.0%, and 4.1%, respectively. The improvement effect was Treatment 2 > Treatment 3 > Treatment 4 > Treatment 6 > Treatment 5.

[0125] 2.4 Effects of different treatments on cadmium, mercury and arsenic content in rice

[0126] After testing, the results of the different treatment groups on the cadmium, mercury and arsenic content of rice are shown in Table 10:

[0127] As can be seen from Table 10, the cadmium content of rice in treatment 1 (CK) was 0.79 mg / kg, the mercury content of rice was 0.03 mg / kg, and the arsenic content was 1.14 mg / kg. Compared with treatment 1, treatments 2, 3, 4, 5, and 6 all reduced the cadmium, mercury, and arsenic contents of rice to a certain extent.

[0128] Among them, the cadmium reduction rates of rice were 75.9%, 70.9%, 69.6%, 31.6% and 37.9% respectively, and the reduction effects were treatment 2 > treatment 3 > treatment 4 > treatment 6 > treatment 5.

[0129] The mercury reduction rates of rice were 60%, 53.3%, 50%, 30% and 36.7% respectively, and the reduction effect was treatment 2 > treatment 3 > treatment 4 > treatment 6 > treatment 5.

[0130] The arsenic reduction rates of rice were 75.4%, 72.8%, 69.3%, 42.9% and 39.5% respectively, and the reduction effects were as follows: Treatment 2 > Treatment 3 > Treatment 4 > Treatment 5 > Treatment 6.

[0131] In summary, the various components of the soil conditioner provided by the present invention cooperate with each other to comprehensively improve the soil from multiple angles, achieving multiple functions of adjusting soil acidity, reducing the content of various heavy metal pollutants such as cadmium, arsenic, and mercury in the soil, improving soil structure, and increasing crop yields. Compared with the unmodified components of the control group, the conditioning effect of the product is faster, stronger, and more stable, and there is no secondary pollution.

[0132] The above descriptions are only some preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multifunctional soil conditioner, characterized in that: It is prepared from the following raw materials in parts by weight: Nanocellulose modified with phosphorus-containing compounds: 5-15 parts; Zinc-aluminum hydrotalcite: 15-25 parts; Magnetic nano-montmorillonite: 25-35 parts; Attapulgite: 30-40 parts; Amino acid mixture: 5-15 parts; The nanocellulose modified by the phosphorus-containing compound is prepared by the following method: taking nanocellulose, dispersing it in deionized water, and preparing a nanocellulose suspension with a mass concentration of 1% to 5%; then adding the phosphorus-containing compound to the nanocellulose suspension, and the mass ratio of the phosphorus-containing compound to the nanocellulose is 1:3; after fully stirring the reaction, centrifuging the reaction solution, washing the separated precipitate, and drying it to a constant weight, the nanocellulose is obtained; The magnetic nano-montmorillonite is prepared by dispersing montmorillonite in a solution containing ferroferric oxide nanoparticles and then modifying it by ultrasonic stirring. The amino acid mixture is a mixture of glycine, alanine and lysine.

2. The multifunctional soil conditioner according to claim 1, characterized in that The phosphorus-containing compound is diammonium hydrogen phosphate or potassium dihydrogen phosphate; The conditions for the stirring reaction of the phosphorus-containing compound and the nanocellulose are: stirring the reaction at a temperature of 30-60° C. and a rotation speed of 200-500 r / min for 2-6 hours.

3. The multifunctional soil conditioner according to claim 2, characterized in that: In the preparation method of nanocellulose modified by phosphorus-containing compounds, the conditions for centrifugal separation of the reaction liquid after the reaction are 3000-5000 r / min for 10-20 minutes; and the drying temperature is 40-60°C.

4. The multifunctional soil conditioner according to claim 1, characterized in that The zinc-aluminum hydrotalcite is prepared by the following method: dissolving a zinc salt, an aluminum salt, and deionized water in a molar ratio of zinc element, aluminum element, and water of 1:1:22, adding an alkaline solution to adjust the pH to 10±0.1, stirring the reaction for 2 hours and then allowing the mixture to stand for precipitation, washing with deionized water, and drying at a temperature of 80-100°C to obtain the zinc-aluminum hydrotalcite.

5. The multifunctional soil conditioner according to claim 1, characterized in that: The preparation method of the magnetic nano-montmorillonite is as follows: montmorillonite is dispersed in an aqueous solution containing ferroferric oxide nanoparticles, wherein the mass ratio of montmorillonite to nano-ferroferric oxide is 1:1 or 2:1; then, under the action of ultrasound, stirring is performed simultaneously to allow the ferroferric oxide nanoparticles to be fully adsorbed on the surface of the montmorillonite, and the conditions for ultrasonic stirring modification are: maintaining the ultrasonic power at 300-400W, and controlling the stirring speed at 300-500r / min for 1-2 hours; then centrifuging and precipitating, washing the precipitate, and vacuum drying to obtain the nano-magnetic montmorillonite.

6. The multifunctional soil conditioner according to claim 5, characterized in that: The conditions for centrifugal precipitation are: centrifugation at a speed of 5000~8000r / min for 10~20min.

7. The multifunctional soil conditioner according to claim 5, characterized in that: The vacuum drying conditions are: drying at 60~80℃ for 12~24 hours under a vacuum degree of -0.08~-0.1MPa.

8. The multifunctional soil conditioner according to claim 1, characterized in that The weight ratio of glycine, alanine and lysine in the amino acid mixture is (1-2):1:

1.

9. A method for preparing the multifunctional soil conditioner according to any one of claims 1 to 8, characterized in that: The specific steps include: The raw materials are weighed according to the weight portions, and then the nanocellulose modified with phosphorus compounds, zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, attapulgite and amino acid mixture are stirred at a speed of 200-300 rpm for 30-60 minutes to be fully stirred and mixed, and then dried at 50-60° C. for 2-3 hours to obtain the multifunctional soil conditioner.

10. Use of the multifunctional soil conditioner according to any one of claims 1 to 8 or the multifunctional soil conditioner prepared by the preparation method according to claim 9 in soil conditioning and restoration, characterized in that: Specifically, 7 to 15 days before rice transplanting, the soil conditioner is spread at 75 to 100 kg / mu, and then ploughed to a depth of 15 to 20 cm to fully mix the soil and the conditioner.

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