A multifunctional soil conditioner and its preparation method and application

Abstract

The present invention provides a multifunctional soil conditioner, its preparation method, and application, relating to the field of soil conditioning technology. The agent comprises 5-15 parts of nanocellulose modified with a phosphorus-containing compound; 15-25 parts of zinc-aluminum hydrotalcite; 25-35 parts of magnetic nanomontmorillonite; 30-40 parts of attapulgite; and 5-15 parts of an amino acid mixture. The phosphorus-modified nanocellulose is prepared by dispersing the nanocellulose in deionized water to form a nanocellulose suspension; and then adding the phosphorus-containing compound to the nanocellulose suspension for modification. The magnetic nanomontmorillonite is prepared by dispersing montmorillonite in an aqueous solution containing ferrosoferric oxide nanoparticles and then modifying it with ultrasonic stirring. The amino acid mixture is a mixture of glycine, alanine, and lysine. The soil conditioner has multiple benefits, including regulating soil pH, reducing the levels of various heavy metal pollutants in the soil, and increasing crop yields. It is pollution-free and has stable effects.

Description

Technical Field

[0001] The present 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 advancement of industrialization and agricultural modernization, soil pollution is becoming increasingly serious. Combined pollution from heavy metals such as cadmium, mercury, and arsenic poses a significant threat to soil quality and crop safety. Furthermore, soil acidification is widespread, leading to a decline in soil fertility and impacting crop growth. Traditional soil conditioners often have complex processes and high costs, and their single function makes them incapable of simultaneously addressing multiple soil issues. Furthermore, these agents can cause secondary contamination during use, or their effectiveness may be limited.

[0003] For example, Chinese patent document CN109053961A discloses a heavy metal ion remediation material for soil remediation and its preparation method. This 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. This soil remediation agent has excellent performance in remediating heavy metal ions in soil, but its production process is complex and its components use highly corrosive materials such as concentrated sulfuric acid and concentrated nitric acid. This requires stringent reaction conditions, is costly, and can have adverse environmental impacts.

[0004] Chinese patent document CN110773119A discloses a multivalent iron-based pillared montmorillonite, its preparation method, and application. This method uses calcium-based nano-montmorillonite as a raw material and an iron salt solution as a pillaring agent. The iron-based pillared nano-montmorillonite is prepared through mixing, aging, reduction, and calcination. The multivalent iron-based pillared nano-montmorillonite prepared by this invention is simple and contains both zero-valent iron and iron oxide. Zero-valent iron with a particle size of 2 to 10 nm accounts for over 90% of the total content. This material can be used as a biofilm growth support, a material for degrading polycyclic aromatic hydrocarbons in soil, and an adsorbent for heavy metal ions. However, the growth of this biofilm may affect the adsorption of heavy metals, and the presence of zero-valent iron and iron oxide can result in poor stability.

[0005] Therefore, it is of great practical significance to develop a multifunctional soil conditioner that can simultaneously reduce the cadmium, mercury, and arsenic contents in the soil, increase the soil pH value, 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, its preparation method, and its application. The soil conditioner provided by the present invention has multiple functions, including regulating soil pH, reducing the levels of various heavy metal pollutants such as cadmium, arsenic, and mercury in the soil, and increasing crop yields. It is pollution-free and can address the multiple problems of existing soil conditioners, such as limited functionality, high cost, and unstable effects.

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

[0015] The magnetic nano-montmorillonite is prepared by dispersing montmorillonite in an aqueous solution containing ferrosoferric oxide nanoparticles and then modifying the solution 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 preparation method of nanocellulose modified with phosphorus-containing compounds, the reaction liquid is centrifuged at 3000-5000 r / min for 10-20 minutes after the reaction; and the drying temperature is 40-60°C.

[0020] Furthermore, the zinc-aluminum hydrotalcite is specifically 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 an alkaline solution to adjust the pH to 10±0.1, stirring and reacting 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, 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 stirring speed at 300-500r / min for 1-2 hours; then centrifuging, 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 the phosphorus compound, zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, attapulgite and amino acid mixture are fully stirred and mixed, 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 200-300 rpm for 30-60 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 remediation. Specifically, 7 to 15 days before rice transplanting, the soil conditioner is spread at a rate of 75 to 100 kg per mu, and the soil is plowed after spreading to a 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 form insoluble phosphate precipitates, such as cadmium phosphate precipitates with cadmium ions, which reduce the mobility and bioavailability of heavy metal ions. Nanocellulose also has a large specific surface area and abundant hydroxyl groups, which can fix cadmium, mercury, and arsenic ions on its surface through physical adsorption and complexation between hydroxyl groups and heavy metal ions. When phosphorus-containing compounds undergo hydrolysis in soil, they may produce hydroxide ions, which 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 this invention can react with heavy metal ions, enhancing their ability to fix them. This improves soil structure, increases soil porosity and aeration, promotes the growth and development of crop roots, and enhances their ability to absorb nutrients and water.

[0037] 5. Amino Acid Mixture: The amino acids provided by this invention are composed of glycine, alanine, and lysine. The amino and carboxyl groups in the amino acid molecules react with cadmium, mercury, and arsenic ions to form stable complexes, reducing the activity and bioavailability of heavy metal ions. Furthermore, the amino acid mixture can serve as an organic nitrogen source and other nutrients, participating in protein synthesis and other metabolic processes in crops, thereby promoting their growth and development.

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

[0039] 1. Synergy of multiple 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 to traditional soil conditioners with a single ingredient, or focusing only on improving soil physical structure, or primarily used to adjust soil pH, the soil conditioner provided by the present invention integrates various ingredients to comprehensively improve soil from multiple angles, achieving the multiple benefits of regulating 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 compounds in the soil conditioner provided by the present invention belong to the category of nanomaterials, and the nanocellulose is modified with phosphorus compounds. Nanomaterials and modified nanomaterials have unique small size effects, surface effects, and quantum size effects, which give them larger specific surface areas and higher reactivity than traditional materials. Moreover, the nanocellulose and nano-montmorillonite modified with phosphorus compounds have faster, stronger, and more stable heavy metal adsorption effects than unmodified nanocellulose and montmorillonite or nanomaterials.

[0041] 3. No secondary pollution. The soil conditioner provided by this invention is primarily made from natural minerals (such as zinc-aluminum hydrotalcite, magnetic nano-montmorillonite, and attapulgite) and biodegradable materials (such as phosphorus-modified nanocellulose and amino acid mixtures). It is environmentally friendly and does not cause secondary pollution. Compared with products containing synthetic chemicals, it better meets the requirements of sustainable agricultural development and contributes to long-term improvements in soil quality and the 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 unrecited element, step, or component. If used in a claim, this phrase renders the claim closed, excluding 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 to specifically disclose 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] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0050] 1. Preparation of multifunctional soil conditioner

[0051] like Figure 1As shown, the present invention provides a multifunctional soil conditioner, the main ingredients of which include 5-15 parts of nanocellulose modified with a phosphorus compound, 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.

[0052] Nanocellulose modified with a phosphorus-containing compound is prepared by the following method: Nanocellulose is dispersed in deionized water to form a nanocellulose suspension with a mass concentration of 1% to 5%. A phosphorus-containing compound, such as diammonium hydrogen phosphate or potassium dihydrogen phosphate, is added to the suspension, and the mass ratio of the phosphorus-containing compound to the nanocellulose is controlled. Excessively high or low mass ratios may result in overreaction or excess phosphorus-containing compound residue. In the present invention, the mass ratio of the phosphorus-containing compound to the nanocellulose is controlled to be 1:3. The reaction is stirred at 200 to 500 rpm at a temperature of 30 to 60°C for 2 to 6 hours. After the reaction is completed, the mixture is centrifuged at a speed of 3000 to 5000 rpm for 10 to 20 minutes. The precipitate is washed 3 to 5 times with deionized water and then dried at 40 to 60°C to constant weight.

[0053] Zinc-aluminum hydrotalcite is prepared by the following method: dissolving a zinc salt, an aluminum salt, and deionized water according to a predetermined molar ratio of zinc, aluminum, and water; adding an alkaline solution to adjust the pH to 10±0.1; stirring and reacting for 2 hours, then allowing the mixture to settle; washing with deionized water, and drying at 80-100°C to obtain the zinc-aluminum hydrotalcite. In a specific embodiment, the zinc salt is any one of zinc nitrate, zinc chloride, zinc sulfate, and zinc acetate; the aluminum 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 during the preparation of the zinc-aluminum hydrotalcite can result in incomplete dissolution of the zinc and aluminum salts, leading to uneven reaction and impurity formation. Therefore, the amount of deionized water in the method should ensure complete dissolution of the zinc and aluminum salts, with a preferred molar ratio of zinc to aluminum to water of 1:1:22.

[0054] Magnetic nano-montmorillonite is prepared by the following method: 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, preferably 1:1. This ratio significantly improves the magnetic properties of the montmorillonite. Ultrasonication is performed at a power of 300-400 W and stirring is controlled at a speed of 300-500 rpm for 1-2 hours to allow the ferroferric oxide nanoparticles to fully adsorb on the montmorillonite surface. The ultrasonically stirred mixed solution is transferred to a centrifuge tube, placed in a centrifuge, and centrifuged at 5000-8000 rpm for 10-20 minutes to precipitate the magnetic nano-montmorillonite. The precipitate is washed with deionized water 3-5 times and dried in a vacuum drying oven at 60-80°C and a vacuum of -0.08-0.1 MPa for 12-24 hours to obtain the 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 prepared raw materials are weighed according to the weight parts, stirred at a speed of 200-300 rpm for 30-60 minutes to fully mix, and then dried at 50-60° C. for 2-3 hours to obtain the multifunctional soil conditioner.

[0058] The present invention is illustrated by the following specific examples. In the following specific embodiments, if no specific conditions are specified, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0059] 1. The phosphorus-modified nanocellulose in each of the following experimental groups was prepared by the following method: nanocellulose was dispersed in deionized water to prepare a nanocellulose suspension with a mass concentration of 6%. To the suspension was added potassium dihydrogen phosphate, a phosphorus-containing compound, in a mass ratio of potassium dihydrogen phosphate to nanocellulose of 1:3. The mixture was stirred at 60°C and 500 rpm for 6 hours. After the reaction, the mixture was centrifuged at 5000 rpm for 20 minutes. The precipitate was washed five times with deionized water and then dried at 60°C to constant weight to obtain phosphorus-modified nanocellulose.

[0060] 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 the molecular formula KH2PO4.

[0061] 2. The zinc-aluminum hydrotalcite in each of 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, and the mixture was stirred for 2 hours and then allowed to settle. The mixture was washed three times with deionized water and dried at 80°C to obtain the 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.

[0063] 3. The magnetic nano-montmorillonite in each experimental group was prepared as follows: Montmorillonite was dispersed in a solution containing ferroferric oxide nanoparticles, with a mass ratio of montmorillonite to nano-ferroferric oxide of 1:1. Ultrasonication was performed at a power of 400 W and stirring was controlled at 500 rpm for 2 hours to allow the ferroferric oxide nanoparticles to fully adsorb on the montmorillonite surface. The ultrasonically stirred mixed solution was transferred to a centrifuge tube and centrifuged at 8000 rpm for 20 minutes to precipitate the magnetic nano-montmorillonite. The precipitate was washed five times with deionized water and dried in a vacuum oven at 80°C and -0.1 MPa for 12 hours to obtain the nano-magnetic montmorillonite.

[0064] Nano-ferroferric oxide was purchased from Luoyang Tongrun Information Technology Co., Ltd., with a spherical shape of 100-200 nm and a purity of 99%. Montmorillonite was purchased from Hunan Hongcheng Ore Powder Co., Ltd., with a density of 2.6 g / cm³ and a viscosity of 70 mPa·s.

[0065] 4. The attapulgite used in the following experimental groups was purchased from Hunan Hongcheng Mineral Powder Co., Ltd., with a grayish white color and 200 mesh.

[0066] 5. The amino acid mixtures in the following experimental groups were prepared by mixing glycine, alanine, and lysine in a weight ratio of 2:1:1. Glycine, alanine, and lysine were purchased from Anhui Weimao Biotechnology Co., Ltd., with an active ingredient content of ≥99%.

[0067] The weight compositions of the main components in each group of Examples and Comparative Examples are shown in Tables 1 to 3 below. The raw materials were weighed according to the proportions of each group in Tables 1 to 3, stirred at 250 rpm for 50 minutes to mix thoroughly, and then dried at 60° C. for 2 hours to obtain soil conditioners of each group (respectively referred to as Example 1, Example 2, Example 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 Table 1, and the montmorillonite in Table 3 uses the unmodified montmorillonite from the same source as Table 1.

[0072] 2. Soil Conditioner Soil Culture Test

[0073] The following test methods are used to determine soil pH, available cadmium, available mercury, and available arsenic, and to determine rice yield, rice cadmium, rice mercury, and rice arsenic content:

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

[0075] (2) Method for determining the weight mean diameter (WMD) of soil aggregates:

[0076] .

[0077] B i is the average diameter of aggregates of any size range screened out, W i The MWD value is the fraction of the mass of aggregates in any size range to the dry mass of the soil sample. A larger MWD value indicates a more stable soil aggregate and a better soil structure.

[0078] (2) Determination of available cadmium in soil: refer to “Determination of available lead and cadmium in soil quality by atomic absorption method” (GB / T23739-2009).

[0079] (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).

[0080] (5) Rice yield determination: refer to the “Operational Specification for Rice Yield Determination” (DB33 / T 2517-2022).

[0081] (6) Method for determination of cadmium in rice: refer to the National Food Safety Standard - Determination of Cadmium in Food (GB 5009.15-2023).

[0082] (7) Mercury determination method for rice: refer to the National Food Safety Standard - Determination of Total Mercury and Organic Mercury in Food (GB5009.17-2014).

[0083] (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).

[0084] 1. Soil culture test

[0085] Indoor soil incubation experiments were conducted using soil collected from an industrial area in Hengyang. The soil had a pH of 5.82, total cadmium of 2.81 mg / kg, total arsenic of 162 mg / kg, total mercury of 3.57 mg / kg, available cadmium of 0.89 mg / kg, available mercury of 0.19 mg / kg, and available arsenic of 17.3 mg / kg.

[0086] Set up 6 processing:

[0087] Treatment 1 (control): no material was applied;

[0088] Treatment 2: The soil conditioner prepared in Example 1 was applied at a dosage of 5 g / bottle;

[0089] Treatment 3: Apply the soil conditioner prepared in Example 2 at a dosage of 5 g / bottle;

[0090] Treatment 4: The soil conditioner prepared in Example 3 was applied at a dosage of 5 g / bottle;

[0091] Treatment 5: The soil conditioner prepared in Comparative Example 1 was applied at a dosage of 5 g / bottle;

[0092] Treatment 6: The soil conditioner prepared in Comparative Example 2 was applied at a dosage of 5 g / bottle.

[0093] 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, maintaining the soil moisture at 60% to 80% of its field capacity.

[0094] Place the plastic culture bottles containing the soil in a constant-temperature incubator at approximately 25°C. After 7, 14, 28, 56, and 63 days of incubation (days represent days), collect appropriate soil samples (approximately 10 g) from each replicate in each treatment group. Use the quartering method to sample, air-dry, grind, and pass through a 0.149 mm sieve before determining heavy metal content. This determination is the same as for the initial soil sample.

[0095] The changes in soil cadmium, mercury and arsenic content under different treatments and different time periods are shown in the following table.

[0096]

[0097]

[0098]

[0099] As can be seen from Tables 4-6, the soil available cadmium, available mercury, and available arsenic contents in both the Examples and the Comparative Examples decreased to a certain extent over time relative to the control group. However, the Examples decreased at a faster rate than the Comparative Examples, with a greater magnitude than the Comparative Examples, particularly at 7 days. At 56 days, the soil heavy metal cadmium, mercury, and arsenic contents in the Examples were essentially stable, while some of the Comparative Examples showed a rebound, indicating that the performance stability of the soil conditioners provided in the Comparative Examples was inferior to that of the soil conditioners provided in the Examples of the present invention.

[0100] 2. Rice Community Experiment

[0101] A rice plot experiment was conducted in a paddy field with Cd, Hg and As complex pollution near an industrial park in Hengyang. The 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, which were randomly arranged in groups. 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.

[0102] The 6 treatments are as follows:

[0103] Treatment 1: Blank (CK), conventional fertilization without any conditioner.

[0104] Treatment 2: conventional fertilization + 100 kg / mu of soil conditioner prepared in Example 1 as a base application.

[0105] Treatment 3: conventional fertilization + 100 kg / mu of soil conditioner prepared in Example 2 as a base application.

[0106] Treatment 4: conventional fertilization + 100 kg / mu of soil conditioner prepared in Example 3 as a base application.

[0107] Treatment 5: conventional fertilization + 100 kg / mu of soil conditioner prepared in Comparative Example 1 as a base application.

[0108] Treatment 6: conventional fertilization + 100 kg / mu of soil conditioner prepared in Comparative Example 2 as a base application.

[0109] In addition to conventional fertilization, the conditioner is evenly spread on the field surface seven days before plowing, either manually or mechanically. A rotary tiller is used to mix the conditioner evenly with the soil. An appropriate amount of water is then applied to stabilize the soil for three days before transplanting the rice. During the rice growing period, weeding, fertilization, pesticide spraying, and irrigation are carried out according to local production management practices.

[0110] 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.

[0111] A 1.5 kg rice sample was collected. The rice was hulled by a huller to obtain rice. The rice was dried and ground, passed through an 80-mesh sieve to remove impurities and particles, and stored in a sealed bag for future use.

[0112] 2.1 Effects of different treatments on soil pH and soil aggregate diameter

[0113] The test results of the effects of different treatment groups on soil physical and chemical properties are shown in Table 7 below:

[0114]

[0115] 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.

[0116] 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.

[0117] The soil WMD values increased by 333%, 322%, 300%, 256%, and 267%, respectively, with the improvement effect in the order of Treatment 2 > Treatment 3 > Treatment 4 > Treatment 6 > Treatment 5. A larger MWD value indicates higher soil aggregate stability and better soil structure.

[0118] 2.2 Effects of different treatments on soil available cadmium, available mercury, and available arsenic contents

[0119] The test results of the effects of different treatment groups on the available cadmium and available arsenic content in the soil are shown in Table 8 below:

[0120]

[0121] 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.

[0122] The reduction rates of soil available cadmium were 57.5%, 53.4%, 50.7%, 39.7% and 42.4% respectively, and the reduction effects were treatment 2 > treatment 3 > treatment 4 > treatment 6 > treatment 5.

[0123] 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.

[0124] 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.

[0125] 2.3 Effects of different treatments on rice yield

[0126] The test results of the effects of different treatment groups on rice yield are shown in Table 9 below:

[0127]

[0128] 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 rice yield to a certain extent, with increases of 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.

[0129] 2.4 Effects of different treatments on cadmium, mercury, and arsenic content in rice

[0130] The test results of the effects of different treatment groups on the cadmium, mercury and arsenic content in rice are shown in Table 10 below:

[0131]

[0132] 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.

[0133] 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.

[0134] 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.

[0135] The arsenic reduction rates of rice were 75.4%, 72.8%, 69.3%, 42.9% and 39.5% respectively, and the reduction effects were treatment 2 > treatment 3 > treatment 4 > treatment 5 > treatment 6.

[0136] In summary, the soil conditioner provided by this invention, through its interplay of various components, can comprehensively improve soil from multiple perspectives, achieving multiple benefits: regulating soil acidity, reducing the levels of heavy metal pollutants such as cadmium, arsenic, and mercury in the soil, improving soil structure, and increasing crop yields. Compared to the unmodified control group, the product's conditioning effects are faster, stronger, and more stable, without any secondary pollution.

[0137] 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 scope of protection 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 phosphorus-containing compound-modified nanocellulose is prepared by the following method: taking nanocellulose, dispersing it in deionized water to prepare a nanocellulose suspension with a mass concentration of 1% to 5%; then adding the phosphorus-containing compound potassium dihydrogen phosphate to the nanocellulose suspension, with the mass ratio of potassium dihydrogen phosphate to nanocellulose being 1:3; stirring and reacting at a temperature of 30 to 60° C. and a speed of 200 to 500 r / min for 2 to 6 hours, centrifuging the reaction solution, washing the separated precipitate, and drying it to a constant weight, thereby obtaining the nanocellulose; 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 and reacting for 2 hours, and then standing to precipitate, washing with deionized water, and drying at a temperature of 80-100°C to obtain; The magnetic nano-montmorillonite is prepared by dispersing montmorillonite in a solution containing ferroferric oxide nanoparticles and then modifying the solution by ultrasonic stirring. The mass ratio of montmorillonite to nano-ferroferric oxide is 1:1 or 2:1; The amino acid mixture is a mixture of glycine, alanine and lysine.

2. The multifunctional soil conditioner according to claim 1, characterized in that In the preparation method of nanocellulose modified with a phosphorus-containing compound, the reaction liquid is centrifuged at 3000-5000 r / min for 10-20 minutes after the reaction; and the drying temperature is 40-60°C.

3. 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; then, under the action of ultrasound, the ferroferric oxide nanoparticles are stirred to fully adsorb on the surface of the montmorillonite. The ultrasonic stirring modification conditions are: maintaining the ultrasonic power at 300-400W and controlling the stirring speed at 300-500 r / min for 1-2 hours; then, centrifuging, washing, and vacuum drying the precipitate to obtain the nano-magnetic montmorillonite.

4. The multifunctional soil conditioner according to claim 3, characterized in that The conditions for centrifugal precipitation are: centrifugation at a speed of 5000~8000r / min for 10~20min.

5. The multifunctional soil conditioner according to claim 3, 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.

6. 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.

7. A method for preparing the multifunctional soil conditioner according to any one of claims 1 to 6, characterized in that: The specific steps include: The raw materials are weighed according to the weight parts, and then the nanocellulose modified with the phosphorus compound, 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 fully stir and mix, and then dried at 50-60° C. for 2-3 hours to obtain the multifunctional soil conditioner.

8. Use of the multifunctional soil conditioner according to any one of claims 1 to 6 or the multifunctional soil conditioner prepared by the preparation method according to claim 7 in soil conditioning and remediation, characterized in that: Specifically, 7 to 15 days before transplanting rice, the soil conditioner is spread at a rate of 75 to 100 kg per mu, and the soil is plowed after spreading to a depth of 15 to 20 cm to fully mix the soil and the conditioner.

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