Soil structure modifier with high molecular water-retaining agent and method for preparing the same

Abstract

The application discloses a preparation method of a soil structure modifier added with a high-molecular water-retaining agent, and belongs to the technical field of soil improvement. The preparation process of the soil structure modifier added with the high-molecular water-retaining agent comprises the following steps: step one, mixing zeolite, medical stone, biochar, furfural residue, humic acid and microbial bacteria liquid, and then adding calcium carbonate and ferrous sulfate in sequence, stirring and mixing, adjusting pH, and obtaining premix; step two, adding a high-molecular water-retaining agent and a composite adsorbent into the premix, stirring and mixing, then adding a stable granule promoting agent, stirring and mixing, drying, granulating, and obtaining the soil structure modifier added with the high-molecular water-retaining agent. The soil structure modifier prepared by the method has excellent water-retaining performance and adsorption pollutant performance, and can effectively improve the soil environment.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to soil structure improvers with added polymer water-retaining agents and their preparation methods. Background Technology

[0002] While traditional soil conditioners have played a role in improving soil physical properties and enhancing fertility, they still have significant shortcomings in water retention and heavy metal ion adsorption capacity. On the one hand, conventional conditioners struggle to effectively retain soil moisture. In arid or semi-arid regions, the problems of rapid water evaporation and weak soil water-holding capacity are particularly pronounced, leading to limited crop growth and insufficient drought resistance in agriculture. On the other hand, facing the increasingly severe problem of heavy metal pollution in soil, traditional conditioners have limited effectiveness in adsorbing and fixing heavy metal ions, failing to meet the needs of contaminated soil remediation. Polymer water-retaining agents, as a novel functional material, offer a new approach to soil structure improvement due to their superior water absorption and retention capabilities.

[0003] CN115322038A discloses a clay soil structure improver, comprising the following substances: 2-8% biochar, 0.2-1% humic acid, 0.005-0.05% organosilicon fertilizer, 1.0-0.5% polyethylene glycol, and the remainder being sand. The method of using this clay soil structure improver is to add a mixture of sand, biochar, humic acid, organosilicon fertilizer, and polyethylene glycol to the bottom of the clay soil tillage layer to maintain the soil bottom layer moisture content at 70-80% of field capacity. Organic and a small amount of chemical fertilizers are then added to the tillage layer to increase the soil's nutrient supply capacity and balance the soil nutrient supply. The soil structure modifier prepared by this method can promote the formation of soil aggregates, improve soil structure, increase soil aeration and permeability, improve soil physical properties, and benefit crop growth and increase crop yield. However, in terms of water retention, although components such as polyethylene glycol and biochar help retain soil moisture to some extent, the water retention effect of the modifier is still insufficient under conditions of extreme drought or long-term drought, when soil moisture evaporates quickly. In terms of pollutant adsorption performance, although components such as biochar and humic acid have a certain adsorption effect on some pollutants, their adsorption effect on some heavy metal ions or recalcitrant organic pollutants is still limited. Summary of the Invention

[0004] The purpose of this invention is to provide a process for preparing a soil structure modifier with added polymeric water-retaining agents, in order to solve the technical problems of poor water retention performance and adsorption performance of pollutants in existing soil structure modifiers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] <First Aspect>

[0007] A method for preparing a soil structure improver with added polymeric water-retaining agent includes the following steps:

[0008] Step 1: Mix zeolite, maifanite, biochar, furfural residue, humic acid, and microbial inoculum. Then add calcium carbonate and ferrous sulfate in sequence, stir and mix, adjust the pH to obtain a premix. The microbial inoculum consists of Lactobacillus plantarum and Bacillus subtilis.

[0009] Step 2: Add the polymer water-retaining agent and composite adsorbent to the premix, mix and stir, then add the stabilizing aggregate promoter, stir and mix, dry, and granulate to obtain the soil structure improver with added polymer water-retaining agent.

[0010] In step one, the ratio of zeolite, maifanite, biochar, furfural residue, humic acid, and microbial inoculum is 50-70 g: 50-70 g: 10-15 g: 2-5 g: 5-10 g: 0.1-1 mL.

[0011] The microbial inoculum includes *Lactobacillus plantarum* and *Bacillus subtilis*; the concentrations of *Lactobacillus plantarum* and *Bacillus subtilis* are 8.5 × 10⁻⁶. 9 CFU / mL and 7.3×10 9 CFU / mL.

[0012] The Lactobacillus plantarum mentioned is Lactiplantibacillus plantarum CICC 20313.

[0013] The Bacillus subtilis strain is Bacillus subtilis CICC 10732.

[0014] In step two, the stabilizing agglomeration promoter includes one or more of bentonite, polyacrylamide, straw-based water-retaining agent, and seaweed extract.

[0015] In step two, the ratio of the amount of polymer water-retaining agent, composite adsorbent, premix and stabilizing granulation promoter is (5-15)g: (3-7)g: (100-120)g: (8-10)g.

[0016] The preparation method of the polymer water-retaining agent includes the following steps:

[0017] Q1: Mix polyol compounds, nitro-substituted aromatic halides with a polar organic solvent, add an inorganic base, and react at 130-140℃ for 20-24h. After post-treatment, nitro-containing intermediate 1 is obtained.

[0018] Q1: The intermediate 1 is reduced by heating in an alcohol solvent in the presence of a catalyst and a reducing agent to obtain an amino-containing intermediate 2;

[0019] Q3: The dicarboxylic acid and the intermediate 2 are reacted in an alcohol solvent at 38-41°C for 6-8 hours with stirring, and the polymeric water-retaining agent is obtained after post-treatment.

[0020] In Q1, the polyol compound is isosorbide, the nitro-substituted aromatic halide is 2-fluoro-3-nitrophenol, the polar organic solvent is N,N-dimethylformamide, and the inorganic base is potassium carbonate; and the ratio of isosorbide, 2-fluoro-3-nitrophenol, N,N-dimethylformamide and potassium carbonate is (7.121-7.493) g : (15.226-16.192) g : (145-155) mL : (13.621-13.972) g, the reaction temperature is 130-140℃, and the reaction time is 20-24 h.

[0021] In Q2, the catalyst is Pd / C, the reducing agent is hydrazine hydrate, and the alcohol solvent is ethanol (anhydrous ethanol).

[0022] In Q2, intermediate 1, Pd / C and anhydrous ethanol are added to a container, heated to 80-84°C, hydrazine hydrate is added, the mixture is refluxed for 20-24 hours, filtered while hot, cooled and then deionized water is added, the mixture is allowed to stand to precipitate, filtered, and vacuum dried to obtain intermediate 2.

[0023] In Q2, the ratio of intermediate 1, Pd / C, ethanol and hydrazine hydrate is (4.11-4.26) g : (0.121-0.129) g : (80-120) mL : (12.5-18) mL.

[0024] Preferably, in Q3, the dicarboxylic acid is terephthalic acid, and the alcohol solvent is anhydrous ethanol.

[0025] Q3 is as follows: Add terephthalic acid and anhydrous ethanol to a container, stir and heat at 38-41℃, then add dropwise a mixed solution of intermediate 2 and anhydrous ethanol, stir and react for 6-8 hours, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0026] In Q3, the ratio of terephthalic acid to intermediate 2 is (1.38-1.94) g : (3.24-3.92) g.

[0027] As one embodiment of the present invention, the preparation method of the polymeric water-retaining agent includes the following steps:

[0028] A: Isosorbide, 2-fluoro-3-nitrophenol and N,N-dimethylformamide were added to a container, stirred and dissolved, potassium carbonate was added, and the mixture was heated to 130-140℃ and reacted for 20-24 hours. After the reaction was completed, deionized water was added, the mixture was allowed to stand, filtered, washed, dried and purified to obtain intermediate 1.

[0029] B: Add intermediate 1, Pd / C and ethanol into a container, heat to 80-84℃, add hydrazine hydrate, reflux for 20-24h, filter while hot, add deionized water after cooling, let stand to precipitate, filter, and vacuum dry to obtain intermediate 2.

[0030] C: Add terephthalic acid and anhydrous ethanol to a container, stir and heat at 38-41℃, then add dropwise a mixed solution of intermediate 2 and anhydrous ethanol, stir and react for 6-8 hours, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0031] The preparation method of the composite adsorbent includes the following steps:

[0032] S1: A halonaphthol compound is mixed with an acidic solvent, an alkylating agent and a haloalkanes solvent are added, and the mixture is reacted at room temperature under an inert gas atmosphere. After filtration and washing, compound A is obtained.

[0033] S2: Compound A is mixed with an alkoxy alkali metal compound, a polar aprotic solvent and a copper salt catalyst, and heated in an inert gas atmosphere. After post-treatment (after the reaction is completed, it is poured into ice water, stirred and dispersed, pH adjusted to 6-7, filtered, dissolved, dried, filtered again, rotary evaporated, concentrated and recrystallized) to obtain compound B.

[0034] S3: The compound B was mixed with a halocarbon solvent, a halomethyl ether compound and a Lewis acid catalyst were added, and the mixture was stirred at low temperature and then reacted at room temperature. After post-treatment (after the reaction was completed, the mixture was poured into a saturated sodium bicarbonate solution, extracted, washed, dried, filtered, rotary evaporated and recrystallized) to obtain compound C.

[0035] S4: The compound C was mixed with a haloalkanes solvent, a deprotecting agent was added at low temperature, and the reaction was carried out at room temperature under inert gas protection. After post-treatment (after the reaction was completed, the mixture was poured into ice water, the pH was adjusted to 5-6, and the mixture was filtered, washed, and filtered again) to obtain compound D.

[0036] S5: The compound D and the aromatic polyamine compound are added to a mixed organic solvent, ultrasonically homogenized, and then an organic acid is added. The reaction is carried out through a freeze-thaw cycle and sealed heating. After post-treatment (after the reaction is completed, the mixture is poured into ice water, the pH is adjusted, and the mixture is filtered, washed, and filtered again) to obtain the composite adsorbent.

[0037] In S1, the halonaphthol compound is 5-bromo-2-naphthol, the acidic solvent is trifluoroacetic acid, the alkylating agent is 1,1,3,3-tetramethoxypropane, and the halohydrocarbon solvent is dichloromethane.

[0038] In S1, the ratio of 5-bromo-2-naphthol, trifluoroacetic acid, 1,1,3,3-tetramethoxypropane and dichloromethane is (30-33) g : (90-110) mL : (10-15) mL : (55-65) mL, and the reaction time is 5-7 h at room temperature.

[0039] In S2, the alkoxy alkali metal compound is sodium methoxide, the polar aprotic solvent is N,N-dimethylformamide, and the copper salt catalyst is cuprous iodide.

[0040] In S2, the ratio of N,N-dimethylformamide, sodium methoxide, compound A and cuprous iodide is (125-180) mL : (7-8.2) g : (8-12) g : (12-14) g, the reaction temperature is 125-135℃, and the reaction time is 5-7 h.

[0041] In S3, the halomethyl ether compound is 1,1-dichloromethyl ether, the Lewis acid catalyst is titanium tetrachloride, and the halohydrocarbon solvent is dichloromethane.

[0042] In S3, the ratio of compound B, dichloromethane, 1,1-dichloromethyl ether and titanium tetrachloride is (3-4.5) g : (100-150) mL : (2.8-4.2) mL : (3-4.5) mL; the low-temperature stirring temperature is 0-1℃, the stirring time is 1-1.5 h, and the room temperature reaction time is 2-3 h.

[0043] In S4, the deprotecting agent is boron tribromide, and the halocarbon solvent is dichloromethane. The ratio of compound C, dichloromethane, and boron tribromide is (2-2.5) g : (80-100) mL : (5-7.4) mL, and the reaction time is 3-5 h at room temperature.

[0044] In S5, the aromatic polyamine compound is tetra(4-aminophenyl)methane, the mixed organic solvent is a mixture of o-dichlorobenzene and N,N-dimethylacetamide, and the organic acid is acetic acid. The ratio of compound D, tetra(4-aminophenyl)methane, o-dichlorobenzene, N,N-dimethylacetamide, and acetic acid is (0.198-0.214) g : (0.088-0.103) g : (5.4-6.3) mL : (0.6-0.9) mL : (1-1.2) mL. The ultrasonic homogenization time is 2-4 min, the sealed heating temperature is 120-124℃, and the stirring time is 3-5 days.

[0045] As one embodiment of the present invention, the preparation method of the composite adsorbent includes the following steps:

[0046] S1: 5-Bromo-2-naphthol was added to trifluoroacetic acid and stirred to mix. Then, a mixed solution of 1,1,3,3-tetramethoxypropane and dichloromethane was added dropwise. The reaction was carried out at room temperature under argon protection. After the reaction was completed, the mixture was filtered and washed to obtain compound A. N,N-dimethylformamide was added to a container containing sodium methoxide. Then, compound A and cuprous iodide were added. The mixture was heated under an argon atmosphere. After the reaction was completed, the mixture was poured into ice water, stirred to disperse, and the pH was adjusted. The mixture was then filtered, dissolved, dried, filtered again, rotary evaporated, concentrated, and recrystallized to obtain compound B.

[0047] S2: Compound B was added to dichloromethane and stirred. After mixing, 1,1-dichloromethyl ether and titanium tetrachloride were added. The mixture was stirred at low temperature and then at room temperature. After stirring, the mixture was poured into a saturated sodium bicarbonate solution, extracted, washed, dried, filtered, rotary evaporated, and recrystallized to obtain compound C.

[0048] S3: Compound C was added to dichloromethane. Boron tribromide was added dropwise under low temperature. After the addition was complete, the reaction was carried out at room temperature under argon protection. After the reaction was completed, the mixture was poured into ice water, the pH was adjusted, and the mixture was filtered, washed, and filtered again to obtain compound D. Compound D and tetra(4-aminophenyl)methane were added to a container, mixed, and then added to a solution of o-dichlorobenzene and N,N-dimethylacetamide. The mixture was homogenized by sonication, followed by the addition of acetic acid, ultrasonic dispersion, freeze-thaw cycle, vacuum sealing, heating and stirring, filtration, washing, and vacuum drying to obtain the composite adsorbent.

[0049] The synthesis reaction formula for the composite adsorbent in the above process is as follows:

[0050]

[0051] Soil structure improvers with added high molecular weight water-retaining agents prepared by the preparation method described above are also within the scope of protection of this invention.

[0052] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0053] 1. In the process of preparing the soil conditioner, the present invention adds a polymer water-retaining agent and a composite adsorbent, which can effectively improve the water retention performance and pollutant adsorption performance of the soil conditioner.

[0054] 2. This invention adds the prepared polymeric water-retaining agent to the soil conditioner, which can effectively improve its water retention performance. The amide bonds and hydroxyl groups contained in the polymeric water-retaining agent molecular chain can form a strong hydrogen bond network through synergistic effect, giving the material high water absorption capacity. The obtained polymeric water-retaining agent integrates rigid and flexible segments, which are connected by amide bonds to form a stable network that combines rigidity and flexibility, effectively resisting osmotic pressure and soil compaction, maintaining structural stability, and improving its long-term stability.

[0055] 3. This invention involves adding the prepared composite adsorbent to a soil conditioner, which can effectively improve its adsorption and water retention performance. The naphthalene structure contained in the composite adsorbent can strongly adsorb pollutants in the soil through π-π stacking and van der Waals forces. The hydroxyl groups contained in the adsorbent can adsorb polar organic pollutants through hydrogen bonds. It can also efficiently capture heavy metal ions through ion exchange or complexation, effectively removing residual organic pollutants and heavy metal ions in the soil, significantly reducing their bioavailability and mobility, and remediating polluted soil. The hydroxyl groups contained in the adsorbent can bind a large number of water molecules through hydrogen bonds. At the same time, the internal pores of the cross-linked network formed can physically bind a large amount of water, synergistically improving the soil's water holding capacity and prolonging water availability. Detailed Implementation

[0056] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0057] In the following embodiments and comparative examples:

[0058] Lactiplantibacillus plantarum CICC 20313; China Industrial Microbial Culture Collection Center

[0059] Bacillus subtilis CICC 10732; China Industrial Microbial Culture Collection Center.

[0060] Example 1

[0061] 1. A method for preparing a polymeric water-retaining agent, comprising the following steps:

[0062] Q1: 7.252g isosorbide, 15.671g 2-fluoro-3-nitrophenol and 150mL N,N-dimethylformamide were added to a container and stirred to dissolve. Then 13.751g potassium carbonate was added, and the mixture was heated to 135℃ and reacted for 24h. After the reaction was completed, the mixture was added to deionized water, allowed to stand, filtered, washed, dried and purified to obtain intermediate 1.

[0063] Q2: Add 4.18g of intermediate 1, 0.125g of Pd / C and 100mL of ethanol to a container, heat to 80℃, then add 15.5mL of hydrazine hydrate, reflux for 24h, after the reaction is complete, filter while hot, cool, add to deionized water, let stand, precipitate, filter, and vacuum dry to obtain intermediate 2.

[0064] Q3: Add 1.64g of terephthalic acid and 12mL of anhydrous ethanol to a container, stir and heat at 40℃, then add dropwise a mixed solution of 3.53g of intermediate 2 and 8mL of anhydrous ethanol. After the addition is complete, stir and react for 6 hours. After the reaction is complete, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0065] 2. A method for preparing a composite adsorbent, comprising the following steps:

[0066] S1: 31.5 mL of 5-bromo-2-naphthol was added to 100 mL of trifluoroacetic acid and stirred. Then, a mixed solution of 12.5 mL of 1,1,3,3-tetramethoxypropane and 60 mL of dichloromethane was added dropwise. The reaction was carried out at room temperature for 6 h under argon protection. After the reaction was completed, the mixture was filtered and washed to obtain compound A. 163 mL of N,N-dimethylformamide was added to a container containing 7.6 g of sodium methoxide. Then, 10 g of compound A and 13 g of cuprous iodide were added. The mixture was heated at 130 °C for 6 h under argon atmosphere. After the reaction was completed, the mixture was poured into ice water, stirred and dispersed, and the pH was adjusted to 6. The mixture was then filtered, dissolved, dried, filtered again, rotary evaporated, concentrated, and recrystallized to obtain compound B.

[0067] S2: 3.75 g of compound B was added to 125 mL of dichloromethane and stirred. After mixing, 3.5 mL of 1,1-dichloromethyl ether and 3.75 mL of titanium tetrachloride were added. The mixture was stirred at 0 °C for 1.5 h and then at room temperature for 3 h. After stirring, the mixture was poured into a saturated sodium bicarbonate solution, extracted, washed, dried, filtered, rotary evaporated, and recrystallized to obtain compound C.

[0068] S3: 2.25 g of compound C was added to 90 mL of dichloromethane. Under low temperature, 6.2 mL of boron tribromide was added dropwise. After the addition was complete, the mixture was reacted at room temperature for 4 h under argon protection. After the reaction was completed, the mixture was poured into ice water, the pH was adjusted to 5, and the mixture was filtered, washed, and filtered again to obtain compound D. 0.208 g of compound D and 0.095 g of tetrakis(4-aminophenyl)methane were added to a container and mixed. The mixture was then added to a solution of 5.7 mL of o-dichlorobenzene and 0.75 mL of N,N-dimethylacetamide. The mixture was sonicated and homogenized for 2 min. Then 1.1 mL of acetic acid was added, and the mixture was sonicated and dispersed. The mixture was subjected to a freeze-thaw cycle, vacuum sealed, heated and stirred at 124 °C for 5 days, filtered, washed, and vacuum dried to obtain the composite adsorbent.

[0069] The mass spectrometry analysis results for compound A were: m / z: 481.93 (100.0%), 479.94 (51.4%), 483.93 (48.6%), 482.94 (25.2%), 480.94 (12.9%), 484.94 (12.5%), 483.94 (3.4%), 481.94 (1.7%), 485.94 (1.7%); the mass spectrometry analysis results for compound B were: m / z: 384.14 (100.0%), 385.14 (27.4%), 386.14 (4.4%); and the mass spectrometry analysis results for compound C were: m / z: 440.13 (100.0%), 441.13 (29.7%), 442.13. (5.4%); The mass spectrometry analysis results of compound D are: m / z: 412.09 (100.0%), 413.10 (27.5%), 414.10 (4.9%).

[0070] 3. A method for preparing a soil conditioner with added polymeric water-retaining agents, comprising the following steps:

[0071] Step 1: Mix 60g zeolite, 60g maifanite, 12.5g biochar, 3.5g furfural residue, 7.5g humic acid, and 0.55mL microbial inoculum. The microbial inoculum consists of 0.25mL of Lactobacillus plantarum and 0.3mL of Bacillus subtilis, with concentrations of 8.5×10⁻⁶. 9 CFU / mL and 7.3×10 9 CFU / mL, then 1g of calcium carbonate and 0.8g of ferrous sulfate were added sequentially, stirred and mixed, and the pH was adjusted to 7 to obtain the premix;

[0072] Step 2: Add 10g of the polymeric water-retaining agent prepared in Example 1 and 5g of the composite adsorbent to 110g of premix, mix and stir, then add 9g of bentonite, stir and mix, dry, and granulate to obtain a soil structure improver with added polymeric water-retaining agent.

[0073] Example 2

[0074] 1. A method for preparing a polymeric water-retaining agent, comprising the following steps:

[0075] Q1: 7.121g isosorbide, 15.226g 2-fluoro-3-nitrophenol and 155mL N,N-dimethylformamide were added to a container and stirred to dissolve. Then 13.621g potassium carbonate was added, and the mixture was heated to 135℃ and reacted for 24h. After the reaction was completed, the mixture was added to deionized water, allowed to stand, filtered, washed, dried and purified to obtain intermediate 1.

[0076] Q2: Add 4.11g of intermediate 1, 0.121g of Pd / C and 80mL of ethanol to a container, heat to 80℃, then add 12.5mL of hydrazine hydrate, reflux for 24h, after the reaction is complete, filter while hot, cool, add to deionized water, let stand, precipitate, filter, and vacuum dry to obtain intermediate 2.

[0077] Q3: Add 1.38g of terephthalic acid and 12mL of anhydrous ethanol to a container, stir and heat at 40℃, then add dropwise a mixed solution of 3.24g of intermediate 2 and 8mL of anhydrous ethanol. After the addition is complete, stir and react for 6 hours. After the reaction is complete, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0078] 2. A method for preparing a composite adsorbent, comprising the following steps:

[0079] S1: 30 mL of 5-bromo-2-naphthol was added to 110 mL of trifluoroacetic acid and stirred. Then, a mixture of 10 mL of 1,1,3,3-tetramethoxypropane and 65 mL of dichloromethane was added dropwise. The reaction was carried out at room temperature for 6 h under argon protection. After the reaction was completed, the mixture was filtered and washed to obtain compound A. 125 mL of N,N-dimethylformamide was added to a container containing 8.2 g of sodium methoxide. Then, 12 g of compound A and 12 g of cuprous iodide were added. The mixture was heated at 130 °C for 6 h under argon atmosphere. After the reaction was completed, the mixture was poured into ice water, stirred and dispersed, and the pH was adjusted to 6. The mixture was then filtered, dissolved, dried, filtered again, rotary evaporated, concentrated, and recrystallized to obtain compound B.

[0080] S2: Add 3g of compound B to 100mL of dichloromethane, stir and mix, then add 4.2mL of 1,1-dichloromethyl ether and 4.5mL of titanium tetrachloride. Stir at 0℃ for 1.5h, then stir at room temperature for 3h. After stirring, pour into a saturated sodium bicarbonate solution, extract, wash, dry, filter, rotary evaporate, and recrystallize to obtain compound C.

[0081] S3: Add 2.5g of compound C to 100mL of dichloromethane. Under low temperature, add 7.4mL of boron tribromide dropwise. After the addition is complete, react at room temperature for 4h under argon protection. After the reaction is complete, pour into ice water, adjust pH=5, filter, wash, and filter again to obtain compound D. Add 0.198g of compound D and 0.088g of tetrakis(4-aminophenyl)methane to a container, mix, and then add to a solution of 5.4mL of o-dichlorobenzene and 0.9mL of N,N-dimethylacetamide. Sonicate to homogenize for 2min, then add 1.2mL of acetic acid, sonicate to disperse, freeze-thaw cycle, vacuum seal, heat and stir at 124℃ for 5 days, filter, wash, and vacuum dry to obtain the composite adsorbent.

[0082] 3. Preparation of soil conditioner with added polymeric water-retaining agent, including the following steps:

[0083] Step 1: Mix 50g zeolite, 70g maifanite, 10g biochar, 3g furfural residue, 7g humic acid, and 0.1mL of microbial inoculum. The microbial inoculum consists of 0.05mL of Lactobacillus plantarum and 0.05mL of Bacillus subtilis, with concentrations of 8.5×10⁻⁶. 9 CFU / mL and 7.3×10 9 CFU / mL, then 1g of calcium carbonate and 0.8g of ferrous sulfate were added sequentially, stirred and mixed, and the pH was adjusted to 7 to obtain the premix;

[0084] Step 2: Add 5g of polymeric water-retaining agent and 3g of composite adsorbent to 100g of premix, mix and stir, then add 8g of bentonite, stir and mix, dry, and granulate to obtain a soil structure improver with added polymeric water-retaining agent.

[0085] Example 3

[0086] 1. A method for preparing a polymeric water-retaining agent, comprising the following steps:

[0087] Q1: 7.493g isosorbide, 16.192g 2-fluoro-3-nitrophenol and 145mL N,N-dimethylformamide were added to a container and stirred to dissolve. Then 13.972g potassium carbonate was added, and the mixture was heated to 135℃ and reacted for 24h. After the reaction was completed, the mixture was added to deionized water, allowed to stand, filtered, washed, dried and purified to obtain intermediate 1.

[0088] Q2: Add 4.26g of intermediate 1, 0.129g of Pd / C and 120mL of ethanol to a container, heat to 80℃, then add 18mL of hydrazine hydrate, reflux for 24h, after the reaction is complete, filter while hot, cool, add to deionized water, let stand, precipitate, filter, and vacuum dry to obtain intermediate 2.

[0089] Q3: Add 1.94g of terephthalic acid and 12mL of anhydrous ethanol to a container, stir and heat at 40℃, then add dropwise a mixed solution of 3.92g of intermediate 2 and 8mL of anhydrous ethanol. After the addition is complete, stir and react for 6 hours. After the reaction is complete, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0090] 2. A method for preparing a composite adsorbent, comprising the following steps:

[0091] S1: 33 mL of 5-bromo-2-naphthol was added to 90 mL of trifluoroacetic acid and stirred. Then, a mixture of 15 mL of 1,1,3,3-tetramethoxypropane and 55 mL of dichloromethane was added dropwise. The reaction was carried out at room temperature for 6 h under argon protection. After the reaction was completed, the mixture was filtered and washed to obtain compound A. 180 mL of N,N-dimethylformamide was added to a container containing 7 g of sodium methoxide. Then, 8 g of compound A and 14 g of cuprous iodide were added. The mixture was heated at 130 °C for 6 h under argon atmosphere. After the reaction was completed, the mixture was poured into ice water, stirred and dispersed, and the pH was adjusted to 6. The mixture was then filtered, dissolved, dried, filtered again, rotary evaporated, concentrated, and recrystallized to obtain compound B.

[0092] S2: Add 4.5g of compound B to 150mL of dichloromethane, stir and mix, then add 2.8mL of 1,1-dichloromethyl ether and 3mL of titanium tetrachloride. Stir at 0℃ for 1.5h, then stir at room temperature for 3h. After stirring, pour into a saturated sodium bicarbonate solution, extract, wash, dry, filter, rotary evaporate, and recrystallize to obtain compound C.

[0093] S3: Add 2g of compound C to 80mL of dichloromethane. Under low temperature, add 5mL of boron tribromide dropwise. After the addition is complete, react at room temperature for 4h under argon protection. After the reaction is complete, pour into ice water, adjust pH=5, filter, wash, and filter again to obtain compound D. Add 0.214g of compound D and 0.103g of tetrakis(4-aminophenyl)methane to a container, mix, and then add to a solution of 6.3mL of o-dichlorobenzene and 0.6mL of N,N-dimethylacetamide. Sonicate to homogenize for 2min, then add 1mL of acetic acid, sonicate to disperse, freeze-thaw cycle, vacuum seal, heat and stir at 124℃ for 5 days, filter, wash, and vacuum dry to obtain the composite adsorbent.

[0094] 3. The preparation process of soil conditioner with added polymer water-retaining agent includes the following steps:

[0095] Step 1: Mix 70g zeolite, 50g maifanite, 15g biochar, 5g furfural residue, 10g humic acid, and 1mL of microbial inoculum. The microbial inoculum consists of 0.5mL of Lactobacillus plantarum and 0.5mL of Bacillus subtilis, with concentrations of 8.5×10⁻⁶. 9CFU / mL and 7.3×10 9 CFU / mL, then 1g of calcium carbonate and 0.8g of ferrous sulfate were added sequentially, stirred and mixed, and the pH was adjusted to 7 to obtain the premix;

[0096] Step 2: Add 15g of polymer water-retaining agent and 7g of composite adsorbent to 120g of premix, mix and stir, then add 10g of bentonite, stir and mix, dry, and granulate to obtain a soil structure improver with added polymer water-retaining agent.

[0097] Example 4

[0098] 1. A method for preparing a polymeric water-retaining agent, comprising the following steps:

[0099] Q1: 7.212 g isosorbide, 15.471 g 2-fluoro-3-nitrophenol and 148 mL N,N-dimethylformamide were added to a container and stirred to dissolve. Then 13.689 g potassium carbonate was added, and the mixture was heated to 135 °C and reacted for 24 h. After the reaction was completed, the mixture was added to deionized water, allowed to stand, filtered, washed, dried and purified to obtain intermediate 1.

[0100] Q2: Add 4.17g of intermediate 1, 0.123g of Pd / C and 90mL of ethanol to a container, heat to 80℃, then add 13.2mL of hydrazine hydrate, reflux for 24h, after the reaction is complete, filter while hot, cool, add to deionized water, let stand, precipitate, filter, and vacuum dry to obtain intermediate 2.

[0101] Q3: Add 1.42g of terephthalic acid and 12mL of anhydrous ethanol to a container, stir and heat at 40℃, then add dropwise a mixed solution of 3.38g of intermediate 2 and 8mL of anhydrous ethanol. After the addition is complete, stir and react for 6 hours. After the reaction is complete, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent.

[0102] 2. A method for preparing a composite adsorbent, comprising the following steps:

[0103] S1: 31 mL of 5-bromo-2-naphthol was added to 95 mL of trifluoroacetic acid and stirred. Then, a mixture of 11 mL of 1,1,3,3-tetramethoxypropane and 58 mL of dichloromethane was added dropwise. The reaction was carried out at room temperature for 6 h under argon protection. After the reaction was completed, the mixture was filtered and washed to obtain compound A. 134 mL of N,N-dimethylformamide was added to a container containing 7.3 g of sodium methoxide. Then, 9 g of compound A and 12.5 g of cuprous iodide were added. The mixture was heated at 130 °C for 6 h under argon atmosphere. After the reaction was completed, the mixture was poured into ice water, stirred and dispersed, and the pH was adjusted to 6. The mixture was then filtered, dissolved, dried, filtered again, rotary evaporated, concentrated, and recrystallized to obtain compound B.

[0104] S2: 3.2 g of compound B was added to 110 mL of dichloromethane and stirred. After mixing, 3.1 mL of 1,1-dichloromethyl ether and 3.2 mL of titanium tetrachloride were added. The mixture was stirred at 0 °C for 1.5 h and then at room temperature for 3 h. After stirring, the mixture was poured into a saturated sodium bicarbonate solution, extracted, washed, dried, filtered, rotary evaporated, and recrystallized to obtain compound C.

[0105] S3: 2.1 g of compound C was added to 85 mL of dichloromethane. Under low temperature, 5.8 mL of boron tribromide was added dropwise. After the addition was complete, the mixture was reacted at room temperature for 4 h under argon protection. After the reaction was completed, the mixture was poured into ice water, the pH was adjusted to 5, and the mixture was filtered, washed, and filtered again to obtain compound D. 0.202 g of compound D and 0.095 g of tetrakis(4-aminophenyl)methane were added to a container and mixed. The mixture was then added to a solution of 5.6 mL of o-dichlorobenzene and 0.7 mL of N,N-dimethylacetamide. The mixture was sonicated and homogenized for 2 min. Then 1.05 mL of acetic acid was added, and the mixture was sonicated and dispersed. The mixture was subjected to a freeze-thaw cycle, vacuum sealed, heated and stirred at 124 °C for 5 days, filtered, washed, and vacuum dried to obtain the composite adsorbent.

[0106] 3. The preparation process of soil conditioner with added polymer water-retaining agent includes the following steps:

[0107] Step 1: Mix 55g zeolite, 55g maifanite, 11g biochar, 4g furfural residue, 8g humic acid, and 0.2mL of microbial inoculum. The microbial inoculum consists of 0.1mL of Lactobacillus plantarum and 0.1mL of Bacillus subtilis, with concentrations of 8.5×10⁻⁶. 9 CFU / mL and 7.3×10 9 CFU / mL, then 1g of calcium carbonate and 0.8g of ferrous sulfate were added sequentially, stirred and mixed, and the pH was adjusted to 7 to obtain the premix;

[0108] Step 2: Add 7g of polymeric water-retaining agent and 4g of composite adsorbent to 105g of premix, mix and stir, then add 8.5g of bentonite, stir and mix, dry, and granulate to obtain a soil structure improver with added polymeric water-retaining agent.

[0109] Comparative Example 1

[0110] Compared with Example 1, Comparative Example 1 did not add a polymeric water-retaining agent during the preparation of the soil structure conditioner with added polymeric water-retaining agent, while all other conditions remained unchanged.

[0111] Comparative Example 2

[0112] Compared with Example 1, Comparative Example 2 did not add a composite adsorbent during the preparation of the soil structure improver with added polymer water-retaining agent, and all other conditions remained unchanged.

[0113] Comparative Example 3

[0114] Compared with Example 1, in the preparation of soil structure conditioner with added polymer water-retaining agent, the amount of polymer water-retaining agent in Comparative Example 3 was reduced to 3g, while other conditions remained unchanged.

[0115] Comparative Example 4

[0116] Compared with Example 1, in the preparation of soil structure improver with added polymer water-retaining agent, the amount of composite adsorbent in Comparative Example 4 was reduced to 2.5g, while other conditions remained unchanged.

[0117] Performance testing:

[0118] Zhengdan 958 was used as the experimental maize variety, with a planting density of 57,000 plants / hm². 2 Traditional flat-planting was used as the control group, while the soil structure improver prepared according to Examples 1-5 and Comparative Examples 1-4 was used as the experimental group. During the application of the soil structure improver, nitrogen, phosphorus, and potassium fertilizers were also added, each at a dosage of 196.5 kg / hm². 2 76.5 kg / hm 2 and 67.5 kg / hm 2 The soil structure conditioner was added at a rate of 250 kg / hm². 2 Simultaneously, the pollutant content in the soil was measured, and the test results are shown in Table 1:

[0119] Table 1

[0120]

[0121] As shown in Table 1, the soil conditioner prepared using the methods of Examples 1-4 exhibits excellent water retention and soil pollutant adsorption performance. A comparison between Comparative Example 1 and Examples 1-4 reveals that adding a polymeric water-retaining agent effectively improves the water retention performance of the soil conditioner. A comparison between Comparative Example 2 and Examples 1-4 shows that adding a composite adsorbent effectively improves both the water retention and soil pollutant adsorption performance of the soil conditioner. A comparison between Comparative Example 3 and Examples 1-4 shows that reducing the amount of polymeric water-retaining agent affects the water retention performance of the soil conditioner. A comparison between Comparative Example 4 and Examples 1-4 shows that reducing the amount of composite adsorbent affects both the water retention and soil pollutant adsorption performance of the soil conditioner; however, due to the still relatively high amount added, it can still adsorb some of the pollutants in the soil.

[0122] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a soil structure improver with added polymeric water-retaining agent, characterized in that, Includes the following steps: Step 1: Mix zeolite, maifanite, biochar, furfural residue, humic acid, and microbial inoculum, then add calcium carbonate and ferrous sulfate in sequence, stir and mix, adjust the pH to obtain a premix; the microorganisms include Lactobacillus plantarum and Bacillus subtilis. Step 2: Add the polymer water-retaining agent and composite adsorbent to the premix, mix and stir, then add the stabilizing aggregate promoter, stir and mix, dry, and granulate to obtain the soil structure improver with added polymer water-retaining agent. The polymeric water-retaining agent is prepared by the following steps: Q1: Mix polyol compounds, nitro-substituted aromatic halides with a polar organic solvent, add an inorganic base, and react at 130-140℃ for 20-24h. After post-treatment, nitro-containing intermediate 1 is obtained. Q2: Add intermediate 1, Pd / C and ethanol into a container, heat to 80-84℃, add hydrazine hydrate, reflux for 20-24h, filter while hot, add deionized water after cooling, let stand to precipitate, filter, and vacuum dry to obtain intermediate 2. Q3: Add terephthalic acid and anhydrous ethanol to a container, stir and heat at 38-41℃, then add dropwise a mixed solution of intermediate 2 and anhydrous ethanol, stir and react for 6-8 hours, wash, filter, and vacuum dry to obtain a polymeric water-retaining agent; In Q1, the polyol compound is isosorbide, the nitro-substituted aromatic halide is 2-fluoro-3-nitrophenol, the polar organic solvent is N,N-dimethylformamide, and the inorganic base is potassium carbonate; and the ratio of isosorbide, 2-fluoro-3-nitrophenol, N,N-dimethylformamide, and potassium carbonate is 7.121-7.493 g : 15.226-16.192 g : 145-155 mL. 13.621-13.972g； The composite adsorbent was prepared by the following steps: S1: A halonaphthol compound is mixed with an acidic solvent, an alkylating agent and a haloalkanes solvent are added, and the mixture is reacted at room temperature under an inert gas atmosphere. After filtration and washing, compound A is obtained. S2: Compound A is mixed with an alkoxy alkali metal compound, a polar aprotic solvent and a copper salt catalyst, and heated in an inert gas atmosphere to react. After post-treatment, compound B is obtained. S3: Compound B is mixed with a halohydrocarbon solvent, a halomethyl ether compound and a Lewis acid catalyst are added, the mixture is stirred at low temperature and then reacted at room temperature, and compound C is obtained after post-treatment. S4: The compound C is mixed with a haloalkanes solvent, a deprotecting agent is added at low temperature, and the reaction is carried out at room temperature under inert gas protection. After post-treatment, compound D is obtained. S5: The compound D and the aromatic polyamine compound are added to a mixed organic solvent, ultrasonically homogenized, and then an organic acid is added. After freezing-thawing cycle and sealed heating reaction, the composite adsorbent is obtained through post-treatment. In S1, the halonaphthol compound is 5-bromo-2-naphthol, the acidic solvent is trifluoroacetic acid, the alkylating agent is 1,1,3,3-tetramethoxypropane, and the halohydrocarbon solvent is dichloromethane. In S2, the alkoxy alkali metal compound is sodium methoxide, the polar aprotic solvent is N,N-dimethylformamide, and the copper salt catalyst is cuprous iodide. In S3, the halomethyl ether compound is 1,1-dichloromethyl ether, the Lewis acid catalyst is titanium tetrachloride, and the halohydrocarbon solvent is dichloromethane; In S4, the deprotecting agent is boron tribromide, and the halohydrocarbon solvent is dichloromethane; In S5, the aromatic polyamine compound is tetrakis(4-aminophenyl)methane, the mixed organic solvent is a mixture of o-dichlorobenzene and N,N-dimethylacetamide, and the organic acid is acetic acid; In step two, the stabilizing agent for accelerators is bentonite.

2. The method for preparing the soil structure improver with added polymeric water-retaining agent according to claim 1, characterized in that, In step one, the ratio of zeolite, maifanite, biochar, furfural residue, humic acid, and microbial inoculum is 50-70g: 50-70g: 10-15g: 2-5g: 5-10g: 0.1-1mL. The microbial inoculum consists of *Lactobacillus plantarum* and *Bacillus subtilis*, with concentrations of 8.5 × 10⁻⁶ g / mL. 9 CFU / mL and 7.3×10 9 CFU / mL; In step two, the ratio of the amount of polymer water-retaining agent, composite adsorbent, premix, and stabilizing agglomerate promoter is 5-15g: 3-7g: 100-120g: 8-10g.

3. The method for preparing the soil structure improver with added polymeric water-retaining agent according to claim 1, characterized in that, In Q2, the ratio of intermediate 1, Pd / C, ethanol and hydrazine hydrate is 4.11-4.26 g : 0.121-0.129 g : 80-120 mL : 12.5-18 mL; In Q3, the ratio of terephthalic acid to intermediate 2 is 1.38-1.94g: 3.24-3.92g.

4. The method for preparing the soil structure improver with added polymeric water-retaining agent according to claim 1, characterized in that, In S1, the ratio of 5-bromo-2-naphthol, trifluoroacetic acid, 1,1,3,3-tetramethoxypropane and dichloromethane is 30-33 g: 90-110 mL: 10-15 mL: 55-65 mL, and the reaction time is 5-7 h at room temperature. And / or, in S2, the ratio of N,N-dimethylformamide, sodium methoxide, compound A and cuprous iodide is 125-180 mL: 7-8.2 g: 8-12 g: 12-14 g, the reaction temperature is 125-135 ℃, and the reaction time is 5-7 h; And / or, in S3, the ratio of compound B, dichloromethane, 1,1-dichloromethyl ether, and titanium tetrachloride is 3-4.5 g: 100-150 mL: 2.8-4.2 mL: 3-4.5 mL; the low-temperature stirring temperature is 0-1℃, the stirring time is 1-1.5 h, and the room temperature reaction time is 2-3 h; And / or, in S4, the ratio of compound C, dichloromethane and boron tribromide is 2-2.5 g: 80-100 mL: 5-7.4 mL, and the reaction time is 3-5 h at room temperature; And / or, in S5, the ratio of compound D, tetrakis(4-aminophenyl)methane, o-dichlorobenzene, N,N-dimethylacetamide, and acetic acid is 0.198-0.214 g : 0.088-0.103 g : 5.4-6.3 mL : 0.6-0.9 mL : 1-1.2 mL, the ultrasonic homogenization time is 2-4 min, the sealed heating temperature is 120-124 ℃, and the stirring time is 3-5 days.

5. The soil structure improver with added high molecular weight water-retaining agent prepared by the preparation method according to any one of claims 1-4.

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