Soil conditioner for soil remediation and preparation process thereof

Abstract

The invention provides a soil conditioner for soil remediation and a preparation process thereof, and belongs to the technical field of soil remediation. The preparation process comprises the following steps: synthesizing a four-arm star polymer; preparing a modified ZSM-5 molecular sieve; preparing a complex microbial inoculant; and preparing the soil conditioner. The ZSM-5 molecular sieve is modified by the four-arm star-shaped polymer, so that proper gaps are kept among soil particles, the air permeability of soil is enhanced, plant root systems can smoothly breathe, root system growth and nutrient absorption are promoted, microorganisms can be protected from being damaged by harmful substances in the soil after the modified ZSM-5 molecular sieve is used for loading microorganisms, and the soil quality is improved. The activity of microorganisms is maintained and the reproduction of the microorganisms is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a soil conditioner for soil remediation and a preparation process thereof. Background Art

[0002] In today's society, with the acceleration of industrialization and urbanization and the changes in agricultural production methods, soil is facing many serious problems and urgently needs efficient solutions.

[0003] On the one hand, soil structural degradation is becoming increasingly common. Long-term, irrational farming practices, such as excessively deep plowing, frequent tillage, and the excessive use of chemical fertilizers and pesticides, have destroyed soil aggregates, reduced porosity, and led to increasingly serious soil compaction. According to relevant survey data, in some traditional agricultural production areas, soil compaction can reach 40%-50% of land cultivated continuously for more than 10 years. This significantly reduces soil air and water permeability, hinders plant root growth, and reduces nutrient absorption efficiency, severely limiting crop yield and quality.

[0004] On the other hand, soil nutrient imbalance has become commonplace. In pursuit of high yields, farmers often favor chemical fertilizers like nitrogen and phosphorus, neglecting the addition of organic fertilizers and trace element fertilizers. This leads to an imbalance in the nutrient ratio in the soil. Nutrients not absorbed by crops are leached away with rainwater, causing environmental problems such as eutrophication. Furthermore, the soil's ability to retain nutrients decreases, making it difficult to continuously provide sufficient nutrients for crop growth, further exacerbating the decline in soil fertility.

[0005] Furthermore, the soil microbial ecosystem has suffered severe damage. The overuse of chemical pesticides, particularly the excessive use of broad-spectrum fungicides and insecticides, indiscriminately kills beneficial microorganisms in the soil, disrupting the original balance of the soil microbial community. The number of beneficial microorganisms has plummeted, and their ecological functions, such as soil organic matter decomposition, nutrient recycling, and pest and disease control, are no longer functioning properly. The soil's self-repair and purification capabilities are lost, creating a vicious cycle that leads to a continuous deterioration of soil quality.

[0006] Furthermore, soil pollution is a serious issue. Industrial waste discharge, wastewater irrigation, and landfills contribute to the accumulation of heavy metal pollutants such as lead, cadmium, mercury, and chromium, as well as organic pollutants such as pesticide residues, petroleum-based substances, and polycyclic aromatic hydrocarbons (PAHs). These pollutants not only affect the soil's physical and chemical properties and reduce productivity, but also accumulate through the food chain, posing a potential threat to human health and raising food safety concerns, sparking widespread public concern.

[0007] Faced with such complex and thorny soil issues, traditional soil remediation and conditioning methods are insufficient. While chemical amendments can adjust soil pH and replenish nutrients in the short term, they often only address the symptoms and are prone to secondary pollution. Physical remediation methods, such as soil addition and deep plowing and sun-drying, are labor-intensive and costly, making them difficult to implement on a large scale. Bioremediation methods, such as relying solely on microbial agents or phytoremediation, are subject to significant environmental constraints, have lengthy restoration cycles, and offer inconsistent results, failing to meet the urgent needs of agricultural production.

[0008] Therefore, we proposed a soil conditioner for soil remediation and its preparation process that can comprehensively solve soil structure, nutrients, microorganisms and pollution problems. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the present invention aims to provide a soil conditioner for soil remediation and a preparation process thereof.

[0010] A preparation process of a soil conditioner for soil remediation comprises the following steps:

[0011] S1: Synthesis of four-arm star polymers

[0012] Pentaerythritol succinate is prepared by using pentaerythritol, succinic anhydride and 4-dimethylaminopyridine, then an intermediate product is prepared by using pentaerythritol succinate, polyethylene glycol, dicyclohexylcarbodiimide and 4-dimethylaminopyridine, and then a four-arm star polymer is prepared by using the intermediate product, succinic anhydride and 4-dimethylaminopyridine;

[0013] S2: Preparation of modified ZSM-5 molecular sieve

[0014] The ZSM-5 molecular sieve is modified by using a four-arm star polymer to obtain a modified ZSM-5 molecular sieve;

[0015] S3: Preparation of compound bacterial agent

[0016] Brevibacillus laterosporus, Bacillus subtilis and Bacillus licheniformis are cultured and fermented to prepare a composite bacterial agent;

[0017] S4: Preparation of soil conditioner

[0018] 40-50 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20-30 parts by weight of tobermorite, 5-8 parts by weight of peat, 5-8 parts by weight of nano-montmorillonite and 10-12 parts by weight of liquid sodium silicate are added to a rotary drum granulator, and then an ammonium humate solution and 17-20 parts by weight of sepiolite powder are added to prepare a soil conditioner.

[0019] Furthermore, the synthesis of the four-arm star polymer in step S1 specifically comprises the following steps:

[0020] S1.1: Add 0.1-0.2 parts by weight of pentaerythritol, 0.6-1 parts by weight of succinic anhydride, and 0.6-1 parts by weight of 4-dimethylaminopyridine to 20-23 parts by weight of N,N-dimethylformamide, and stir the mixture at 60-65°C under a nitrogen atmosphere for 25-25 hours. After the reaction is completed, perform vacuum distillation at 70-75°C to obtain a mixed product, dissolve the mixed product in 20-30 parts by weight of a CH2Cl2 solution, extract the mixture with 1 mol / L dilute hydrochloric acid, and wash the mixture 2-3 times with deionized water. Dry the washed product to obtain pentaerythritol succinate;

[0021] S1.2: 0.1-0.2 parts by weight of pentaerythritol succinate, 0.7-1 parts by weight of polyethylene glycol, 0.6-0.8 parts by weight of dicyclohexylcarbodiimide, and 0.6-0.8 parts by weight of 4-dimethylaminopyridine are added to 20-23 parts by weight of N,N-dimethylformamide, and stirred at 120-125°C under a nitrogen atmosphere for 25-25 hours. After the reaction is completed, 100-120 parts by weight of deionized water are added to the product, and the product is vacuum filtered and rotary evaporated. The crude product is extracted with 1 mol / L dilute hydrochloric acid and CHCl, and then washed 2-3 times with 10% NaCl solution. Finally, the organic phase is precipitated with diethyl ether and dried under vacuum at 50-60°C overnight to obtain an intermediate product;

[0022] S1.3: Add 0.1-0.2 parts by weight of the intermediate product, 0.6-1 parts by weight of succinic anhydride and 0.6-1 parts by weight of 4-dimethylaminopyridine to 20-23 parts by weight of N,N-dimethylformamide and stir the mixture at 60-65°C in a nitrogen atmosphere for 25-25 hours. After the reaction is completed, perform reduced pressure distillation at 70-75°C to obtain a mixed product. Dissolve the mixed product in 20-30 parts by weight of CH2Cl2 solution, extract with 1 mol / L dilute hydrochloric acid, and wash with deionized water 2-3 times. Dry the washed product to obtain a four-arm star polymer.

[0023] Furthermore, the preparation of the modified ZSM-5 molecular sieve in step S2 specifically includes the following steps:

[0024] S2.1: Dissolve 20-30 parts by weight of sodium hydroxide in 100-120 parts by weight of deionized water, then add 10-20 parts by weight of silica sol containing 25% silicon dioxide and 2-5 parts by weight of sodium aluminate, and stir at 200-300 rpm for 20-30 hours to obtain a mixed solution;

[0025] S2.2: Transfer the mixed solution to a reactor and heat at 180-200°C for 24-25 hours. After the reaction is complete, separate the product by vacuum filtration and wash it with deionized water several times until the supernatant becomes a neutral solution. Dry the product to obtain ZSM-5 molecular sieve.

[0026] S2.3: Add the obtained ZSM-5 molecular sieve to a mixed solvent of 20-30 parts by weight of ethanol, 5-8 parts by weight of deionized water, and 0.7-1 parts by weight of ammonium hydroxide, and ultrasonically disperse for 20-30 minutes. Then, add 0.3-0.5 parts by weight of KH-792, and react at 60-65°C for 20-24 hours. After the reaction is completed, wash with ethanol and deionized water 3-5 times respectively, and centrifuge and dry to obtain NH2-ZSM-5 molecular sieve;

[0027] S2.4: Dissolve 8-10 parts by weight of a four-arm star polymer, 3-5 parts by weight of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2-3 parts by weight of 4-dimethylaminopyridine in 50-80 parts by weight of N,N-dimethylformamide solution to obtain a mixed solution, disperse 4-5 parts by weight of NH2-ZSM-5 molecular sieve in the mixed solution, stir at 60-65°C under a nitrogen atmosphere for 24-25 hours, and after the reaction is completed, dissolve the product in 20-30 parts by weight of a CH2Cl2 solution, then extract with 1 mol / L dilute hydrochloric acid, and wash with deionized water 2-3 times. Dry the washed product to obtain a modified ZSM-5 molecular sieve.

[0028] Furthermore, step S3 of preparing the composite bacterial agent specifically includes the following steps:

[0029] S3.1: Inoculating Brevibacillus laterosporus, Bacillus subtilis, and Bacillus licheniformis into seed culture medium for cultivation, respectively, to obtain Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution;

[0030] S3.2: Combine sucrose, lactose, maltose, soluble starch, peptone, yeast extract, urea, NaCl, K2SO4, K2HPO4, MgSO4·7H2O, CaCl2, CaCO3, and water, adjust the pH to 8.0, sterilize at 121°C for 45-50 minutes, and cool to 34°C to obtain a culture medium;

[0031] S3.3: Mix the seed liquid of Brevibacillus laterosporus, the seed liquid of Bacillus subtilis, and the seed liquid of Bacillus licheniformis at a ratio of 1:1:1 to obtain a mixed seed liquid, add the mixed seed liquid into a fermentation tank at a ratio of 5% of the volume of the culture medium, and culture at 35°C with oxygen and stirring for 16-20 hours to obtain a composite bacterial agent.

[0032] Furthermore, the components of the culture medium in S3.2 are specifically sucrose 15%, lactose 12%, maltose 5%, soluble starch 5%, peptone 15%, yeast extract 9%, urea 5%, NaCl 8%, K2SO4 1.0%, K2HPO4 1.5%, MgSO4·7H2O 3.5%, CaCl2 1.5%, CaCO3 6.5%, and the balance is water.

[0033] Furthermore, step S4 of preparing the soil conditioner specifically includes the following steps:

[0034] S4.1: Dissolve 1-2 parts by weight of tris(hydroxymethyl)aminomethane hydrochloride in 50-60 parts by weight of deionized water, adjust the pH to 8.5, then add 1-2 parts by weight of modified ZSM-5 molecular sieve and ultrasonically disperse for 10-15 minutes. Then, add 2-3 parts by weight of the composite bacterial agent and stir at 32-35°C for 24-25 hours. After the reaction is completed, a ZSM-5 molecular sieve loaded with composite bacteria is obtained.

[0035] S4.2: 5-10 parts by weight of fly ash and 1.2-2 parts by weight of calcium hydroxide are mixed and added to a polytetrafluoroethylene-lined autoclave. The mixture is reacted in a homogeneous reactor at 200-230°C for 6-8 hours. After the reaction is completed, the slurry is cooled to room temperature, filtered with filter paper, and washed with deionized water. The product is then dried in an oven to obtain tobermorite;

[0036] S4.3: Add 2-3 parts by weight of ammonia water, 10-15 parts by weight of humic acid and 30-40 parts by weight of water to a sealed reaction tank, heat and stir for 15-20 minutes to prepare an ammonium humate solution, then add 40-50 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20-30 parts by weight of tobermorite, 5-8 parts by weight of peat, 5-8 parts by weight of nano-montmorillonite and 10-12 parts by weight of liquid sodium silicate to a rotary drum granulator, then add the ammonium humate solution and 17-20 parts by weight of sepiolite powder, and granulate to obtain a soil conditioner after granulation.

[0037] A soil conditioner for soil remediation, prepared by any of the above-mentioned processes for preparing a soil conditioner for soil remediation.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] 1. The present invention modifies the ZSM-5 molecular sieve by a four-arm star polymer. The unique structure of the four-arm star polymer makes it stretch in the soil and intertwine with the soil particles. The ZSM-5 molecular sieve further stabilizes the soil structure and prevents soil compaction by virtue of its own porous characteristics. This combination is like building a stable "scaffold" for the soil, so that appropriate gaps are maintained between soil particles, enhancing the air permeability of the soil, allowing plant roots to breathe smoothly, promoting root growth and nutrient absorption, and the modified ZSM-5 molecular sieve has a large specific surface area and rich pore structure. It can adsorb nutrient ions in the soil, such as ammonium ions and phosphate ions, and store these nutrients to play the role of a "nutrient bank". When the nutrient concentration in the soil is reduced, it can be slowly released, continuously providing the required nutrition for plant growth, reducing the leaching and waste of fertilizers, and improving fertilizer utilization.

[0040] 2. The modified ZSM-5 molecular sieve loaded with microorganisms provides an ideal habitat for microorganisms. Its porous structure can not only protect microorganisms from harmful substances in the soil, but also enable microorganisms to maintain moderate material exchange with the external environment, thereby maintaining the activity of microorganisms. Under drought conditions, the moisture inside the molecular sieve can provide a certain survival guarantee for microorganisms. In terms of nutrient supply, the nutrients adsorbed by the molecular sieve can also be used by microorganisms, promoting the reproduction of microorganisms. The three loaded Bacillus species all have strong phosphate solubility capabilities, and can convert insoluble phosphorus compounds in the soil, such as calcium phosphate and iron phosphate, into soluble phosphorus forms that can be absorbed and utilized by plants, providing sufficient phosphorus nutrition for plant growth and promoting root development, flowering and fruiting.

[0041] 3. The nano-sized montmorillonite in the soil conditioner prepared by the present invention has a strong adsorption capacity for heavy metal ions in the soil, such as lead, cadmium, and mercury. Through ion exchange and surface complexation, the heavy metal ions are fixed in its crystal lattice, reducing the mobility and bioavailability of heavy metals in the soil, reducing the toxicity of heavy metals to plant roots, and ensuring the quality and safety of agricultural products. The crystal structure of tobermorite contains a large number of active sites, which can also adsorb a certain amount of heavy metal ions. It works synergistically with montmorillonite to enhance the prevention and control of heavy metal pollution in the soil and cut off the risk of heavy metal pollution transmission through the food chain at the source. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, further serve to explain the principles of the invention and to enable one skilled in the art to make and use the invention.

[0043] Figure 1 This is a flow chart of a process for preparing a soil conditioner for soil remediation adopted in an embodiment of the present invention;

[0044] Figure 2 FTIR spectra of pentaerythritol succinate, intermediate product and four-arm star polymer of the present invention. DETAILED DESCRIPTION

[0045] The following describes in detail a process for preparing a soil conditioner for soil remediation provided by the present invention, in conjunction with the accompanying drawings and specific examples. It is also noted that, to provide a more detailed description, the following examples are best and preferred embodiments, and those skilled in the art may also adopt other alternatives for implementing certain known technologies. Furthermore, the accompanying drawings are only for the purpose of describing the embodiments in more detail and are not intended to limit the present invention.

[0046] Example 1

[0047] A preparation process of a soil conditioner for soil remediation, such as Figure 1-Figure 2 As shown, the following steps are included:

[0048] S1: Synthesis of four-arm star polymers

[0049] S1.1: 0.1 parts by weight of pentaerythritol, 0.6 parts by weight of succinic anhydride, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide, and stirred at 60°C under a nitrogen atmosphere for 25 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 70°C to obtain a mixed product, which was dissolved in 20 parts by weight of a CH2Cl2 solution, then extracted with 1 mol / L dilute hydrochloric acid, and washed twice with deionized water. The washed product was dried to obtain pentaerythritol succinate;

[0050] S1.2: 0.1 parts by weight of pentaerythritol succinate, 0.7 parts by weight of polyethylene glycol, 0.6 parts by weight of dicyclohexylcarbodiimide, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide, and stirred at 120°C under a nitrogen atmosphere for 25 hours. After the reaction, 100 parts by weight of deionized water were added to the product, and the mixture was vacuum filtered and rotary evaporated. The crude product was extracted with 1 mol / L dilute hydrochloric acid and CH2Cl2, and then washed twice with 10% NaCl solution. Finally, the organic phase was precipitated with diethyl ether and dried under vacuum at 50°C overnight to obtain an intermediate product.

[0051] S1.3: 0.1 parts by weight of the intermediate product, 0.6 parts by weight of succinic anhydride, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide and stirred at 60°C under a nitrogen atmosphere for 25 hours. After completion of the reaction, the mixture was distilled under reduced pressure at 70°C to obtain a mixed product. The mixed product was dissolved in 20 parts by weight of a CH2Cl2 solution, extracted with 1 mol / L dilute hydrochloric acid, and washed twice with deionized water. The washed product was dried to obtain a four-arm star polymer.

[0052] S2: Preparation of modified ZSM-5 molecular sieve

[0053] S2.1: Dissolve 20 parts by weight of sodium hydroxide in 100 parts by weight of deionized water, then add 10 parts by weight of silica sol containing 25% silicon dioxide and 2 parts by weight of sodium aluminate, and stir at 200 rpm for 20 hours to obtain a mixed solution;

[0054] S2.2: The mixed solution is transferred to a reactor and heated at 180°C for 24 hours. After the reaction is complete, the product is separated by vacuum filtration and washed with deionized water several times until the supernatant becomes a neutral solution. The product is then dried to obtain ZSM-5 molecular sieve.

[0055] S2.3: The obtained ZSM-5 molecular sieve was added to a mixed solvent of 20 parts by weight of ethanol, 5 parts by weight of deionized water and 0.7 parts by weight of ammonium hydroxide, and ultrasonically dispersed for 20 minutes. Then, 0.3 parts by weight of KH-792 was added and reacted at 60°C for 20 hours. After the reaction was completed, the mixture was washed with ethanol and deionized water three times respectively, and centrifuged and dried to obtain NH2-ZSM-5 molecular sieve;

[0056] S2.4: 8 parts by weight of a four-arm star polymer, 3 parts by weight of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2 parts by weight of 4-dimethylaminopyridine were dissolved in 50 parts by weight of N,N-dimethylformamide solution to obtain a mixed solution, 4 parts by weight of NH2-ZSM-5 molecular sieve were dispersed in the mixed solution, and stirred at 60°C under a nitrogen atmosphere for 24 hours. After the reaction was completed, the product was dissolved in 20 parts by weight of a CH2Cl2 solution, and then extracted with 1 mol / L dilute hydrochloric acid and washed twice with deionized water. The washed product was dried to obtain a modified ZSM-5 molecular sieve;

[0057] S3: Preparation of compound bacterial agent

[0058] S3.1: Inoculating Brevibacillus laterosporus, Bacillus subtilis, and Bacillus licheniformis into seed culture medium for cultivation, respectively, to obtain Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution;

[0059] S3.2: Mix 15% sucrose, 12% lactose, 5% maltose, 5% soluble starch, 15% peptone, 9% yeast extract, 5% urea, 8% NaCl, 1.0% K2SO4, 1.5% K2HPO4, 3.5% MgSO4·7H2O, 1.5% CaCl2, 6.5% CaCO3, and the balance water, adjust the pH to 8.0, sterilize at 121°C for 45-50 minutes, and cool to 34°C to obtain a culture medium;

[0060] S3.3: Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution were mixed at a ratio of 1:1:1 to obtain a mixed seed solution. The mixed seed solution was added to a fermenter at a ratio of 5% by volume of the culture medium, and cultured at 35°C with aeration and stirring for 16 hours to obtain a composite bacterial agent.

[0061] S4: Preparation of soil conditioner

[0062] S4.1: Dissolve 1 part by weight of tris(hydroxymethyl)aminomethane hydrochloride in 50 parts by weight of deionized water, adjust the pH to 8.5, then add 1 part by weight of modified ZSM-5 molecular sieve and disperse it ultrasonically for 10 minutes. Then, add 2 parts by weight of the composite bacterial agent and stir at 32°C for 24 hours. After the reaction is completed, a ZSM-5 molecular sieve loaded with composite bacteria is obtained.

[0063] S4.2: 5 parts by weight of fly ash and 1.2 parts by weight of calcium hydroxide were mixed and added to a polytetrafluoroethylene-lined autoclave. The mixture was reacted in a homogeneous reactor at 200°C for 6 hours. After the reaction, the slurry was cooled to room temperature, filtered with filter paper, and washed with deionized water. The product was then dried in an oven to obtain tobermorite.

[0064] S4.3: Add 2 parts by weight of ammonia water, 10 parts by weight of humic acid and 30 parts by weight of water into a sealed reaction tank, heat and stir for 15 minutes to prepare an ammonium humate solution, then add 40 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20 parts by weight of tobermorite, 5 parts by weight of peat, 5 parts by weight of nano-montmorillonite and 10 parts by weight of liquid sodium silicate into a rotary drum granulator, then add the ammonium humate solution and 17 parts by weight of sepiolite powder, and granulate to obtain a soil conditioner after granulation.

[0065] Example 2

[0066] A preparation process of a soil conditioner for soil remediation, such as Figure 1-Figure 2 As shown, the following steps are included:

[0067] S1: Synthesis of four-arm star polymers

[0068] S1.1: 0.2 parts by weight of pentaerythritol, 1 part by weight of succinic anhydride, and 1 part by weight of 4-dimethylaminopyridine were added to 23 parts by weight of N,N-dimethylformamide, and stirred at 60°C under a nitrogen atmosphere for 25 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 70°C to obtain a mixed product, which was dissolved in 30 parts by weight of a CH2Cl2 solution, then extracted with 1 mol / L dilute hydrochloric acid, and washed twice with deionized water. The washed product was dried to obtain pentaerythritol succinate;

[0069] S1.2: 0.2 parts by weight of pentaerythritol succinate, 1 part by weight of polyethylene glycol, 0.8 parts by weight of dicyclohexylcarbodiimide, and 0.8 parts by weight of 4-dimethylaminopyridine were added to 23 parts by weight of N,N-dimethylformamide, and stirred at 120°C under a nitrogen atmosphere for 25 hours. After the reaction, 120 parts by weight of deionized water were added to the product, and the mixture was vacuum filtered and rotary evaporated. The crude product was extracted with 1 mol / L dilute hydrochloric acid and CHCl, and then washed twice with 10% NaCl solution. Finally, the organic phase was precipitated with diethyl ether and dried under vacuum at 50°C overnight to obtain an intermediate product.

[0070] S1.3: 0.2 parts by weight of the intermediate product, 1 part by weight of succinic anhydride, and 1 part by weight of 4-dimethylaminopyridine were added to 23 parts by weight of N,N-dimethylformamide and stirred at 60°C under a nitrogen atmosphere for 25 hours. After completion of the reaction, the mixture was distilled under reduced pressure at 70°C to obtain a mixed product, which was dissolved in 30 parts by weight of a CH2Cl2 solution, extracted with 1 mol / L dilute hydrochloric acid, and washed twice with deionized water. The washed product was dried to obtain a four-arm star polymer;

[0071] S2: Preparation of modified ZSM-5 molecular sieve

[0072] S2.1: 30 parts by weight of sodium hydroxide were dissolved in 120 parts by weight of deionized water, followed by the addition of 20 parts by weight of a silica sol containing 25% silicon dioxide and 5 parts by weight of sodium aluminate, and the mixture was stirred at 200 rpm for 20 hours to obtain a mixed solution;

[0073] S2.2: The mixed solution is transferred to a reactor and heated at 180°C for 24 hours. After the reaction is complete, the product is separated by vacuum filtration and washed with deionized water several times until the supernatant becomes a neutral solution. The product is then dried to obtain ZSM-5 molecular sieve.

[0074] S2.3: The obtained ZSM-5 molecular sieve was added to a mixed solvent of 30 parts by weight of ethanol, 8 parts by weight of deionized water and 1 part by weight of ammonium hydroxide, and ultrasonically dispersed for 20 minutes. Then, 0.5 parts by weight of KH-792 was added and reacted at 60°C for 20 hours. After the reaction was completed, the mixture was washed with ethanol and deionized water three times respectively, and then centrifuged and dried to obtain NH2-ZSM-5 molecular sieve;

[0075] S2.4: 10 parts by weight of a four-arm star polymer, 5 parts by weight of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 3 parts by weight of 4-dimethylaminopyridine were dissolved in 80 parts by weight of N,N-dimethylformamide solution to obtain a mixed solution, 5 parts by weight of NH2-ZSM-5 molecular sieve were dispersed in the mixed solution, and the mixture was stirred at 60°C under a nitrogen atmosphere for 24 hours. After the reaction was completed, the product was dissolved in 30 parts by weight of CH2Cl2 solution, and then extracted with 1 mol / L dilute hydrochloric acid and washed twice with deionized water. The washed product was dried to obtain a modified ZSM-5 molecular sieve;

[0076] S3: Preparation of compound bacterial agent

[0077] S3.1: Inoculating Brevibacillus laterosporus, Bacillus subtilis, and Bacillus licheniformis into seed culture medium for cultivation, respectively, to obtain Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution;

[0078] S3.2: Mix 15% sucrose, 12% lactose, 5% maltose, 5% soluble starch, 15% peptone, 9% yeast extract, 5% urea, 8% NaCl, 1.0% K2SO4, 1.5% K2HPO4, 3.5% MgSO4·7H2O, 1.5% CaCl2, 6.5% CaCO3, and the balance water, adjust the pH to 8.0, sterilize at 121°C for 45-50 minutes, and cool to 34°C to obtain a culture medium;

[0079] S3.3: Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution were mixed at a ratio of 1:1:1 to obtain a mixed seed solution. The mixed seed solution was added to a fermenter at a ratio of 5% by volume of the culture medium, and cultured at 35°C with aeration and stirring for 16 hours to obtain a composite bacterial agent.

[0080] S4: Preparation of soil conditioner

[0081] S4.1: Dissolve 2 parts by weight of tris(hydroxymethyl)aminomethane hydrochloride in 60 parts by weight of deionized water, adjust the pH to 8.5, then add 2 parts by weight of modified ZSM-5 molecular sieve and disperse by ultrasonication for 10 minutes. Then, add 3 parts by weight of the composite bacterial agent and stir at 32°C for 24 hours. After the reaction is completed, a ZSM-5 molecular sieve loaded with the composite bacteria is obtained.

[0082] S4.2: 10 parts by weight of fly ash and 2 parts by weight of calcium hydroxide were mixed and added to a polytetrafluoroethylene-lined autoclave. The mixture was reacted in a homogeneous reactor at 200°C for 6 hours. After the reaction, the slurry was cooled to room temperature, filtered with filter paper, and washed with deionized water. The product was then dried in an oven to obtain tobermorite.

[0083] S4.3: Add 3 parts by weight of ammonia water, 15 parts by weight of humic acid and 40 parts by weight of water into a sealed reaction tank, heat and stir for 15 minutes to prepare an ammonium humate solution, then add 50 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 30 parts by weight of tobermorite, 8 parts by weight of peat, 8 parts by weight of nano-montmorillonite and 12 parts by weight of liquid sodium silicate into a rotary drum granulator, then add the ammonium humate solution and 20 parts by weight of sepiolite powder, and granulate to obtain a soil conditioner after granulation.

[0084] Example 3

[0085] A preparation process of a soil conditioner for soil remediation, such as Figure 1-Figure 2 As shown, the following steps are included:

[0086] S1: Synthesis of four-arm star polymers

[0087] S1.1: 0.1 parts by weight of pentaerythritol, 0.6 parts by weight of succinic anhydride, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide, and stirred at 65°C under a nitrogen atmosphere for 25 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 75°C to obtain a mixed product, which was dissolved in 20 parts by weight of a CH2Cl2 solution, then extracted with 1 mol / L dilute hydrochloric acid, and washed three times with deionized water. The washed product was dried to obtain pentaerythritol succinate;

[0088] S1.2: 0.1 parts by weight of pentaerythritol succinate, 0.7 parts by weight of polyethylene glycol, 0.6 parts by weight of dicyclohexylcarbodiimide, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide, and stirred at 125°C under a nitrogen atmosphere for 25 hours. After the reaction, 100 parts by weight of deionized water were added to the product, and the mixture was vacuum filtered and rotary evaporated. The crude product was extracted with 1 mol / L dilute hydrochloric acid and CH2Cl2, and then washed three times with 10% NaCl solution. Finally, the organic phase was precipitated with diethyl ether and dried under vacuum at 60°C overnight to obtain an intermediate product.

[0089] S1.3: 0.1 parts by weight of the intermediate product, 0.6 parts by weight of succinic anhydride, and 0.6 parts by weight of 4-dimethylaminopyridine were added to 20 parts by weight of N,N-dimethylformamide and stirred at 65°C under a nitrogen atmosphere for 25 hours. After completion of the reaction, the mixture was distilled under reduced pressure at 75°C to obtain a mixed product. The mixed product was dissolved in 20 parts by weight of a CH2Cl2 solution, extracted with 1 mol / L dilute hydrochloric acid, and washed three times with deionized water. The washed product was dried to obtain a four-arm star polymer.

[0090] S2: Preparation of modified ZSM-5 molecular sieve

[0091] S2.1: 20 parts by weight of sodium hydroxide were dissolved in 100 parts by weight of deionized water, followed by the addition of 10 parts by weight of a silica sol containing 25% silicon dioxide and 2 parts by weight of sodium aluminate, and the mixture was stirred at 300 rpm for 30 hours to obtain a mixed solution;

[0092] S2.2: The mixed solution is transferred to a reactor and heated at 200°C for 25 hours. After the reaction is complete, the product is separated by vacuum filtration and washed with deionized water multiple times until the supernatant becomes a neutral solution. The product is then dried to obtain ZSM-5 molecular sieve.

[0093] S2.3: The obtained ZSM-5 molecular sieve was added to a mixed solvent of 20 parts by weight of ethanol, 5 parts by weight of deionized water, and 0.7 parts by weight of ammonium hydroxide, and ultrasonically dispersed for 30 minutes. Then, 0.3 parts by weight of KH-792 was added and reacted at 65°C for 24 hours. After the reaction was completed, the mixture was washed with ethanol and deionized water five times respectively, and centrifuged and dried to obtain NH2-ZSM-5 molecular sieve;

[0094] S2.4: 8 parts by weight of a four-arm star polymer, 3 parts by weight of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2 parts by weight of 4-dimethylaminopyridine were dissolved in 50 parts by weight of N,N-dimethylformamide solution to obtain a mixed solution, 4 parts by weight of NH2-ZSM-5 molecular sieve were dispersed in the mixed solution, and the mixture was stirred at 65°C under a nitrogen atmosphere for 25 hours. After the reaction was completed, the product was dissolved in 20 parts by weight of CH2Cl2 solution, and then extracted with 1 mol / L dilute hydrochloric acid and washed three times with deionized water. The washed product was dried to obtain a modified ZSM-5 molecular sieve;

[0095] S3: Preparation of compound bacterial agent

[0096] S3.1: Inoculating Brevibacillus laterosporus, Bacillus subtilis, and Bacillus licheniformis into seed culture medium for cultivation, respectively, to obtain Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution;

[0097] S3.2: Mix 15% sucrose, 12% lactose, 5% maltose, 5% soluble starch, 15% peptone, 9% yeast extract, 5% urea, 8% NaCl, 1.0% K2SO4, 1.5% K2HPO4, 3.5% MgSO4·7H2O, 1.5% CaCl2, 6.5% CaCO3, and the balance water, adjust the pH to 8.0, sterilize at 121°C for 45-50 minutes, and cool to 34°C to obtain a culture medium;

[0098] S3.3: Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution were mixed at a ratio of 1:1:1 to obtain a mixed seed solution. The mixed seed solution was added to a fermenter at a ratio of 5% by volume of the culture medium, and cultured at 35°C with aeration and stirring for 20 hours to obtain a composite bacterial agent.

[0099] S4: Preparation of soil conditioner

[0100] S4.1: Dissolve 1 part by weight of tris(hydroxymethyl)aminomethane hydrochloride in 50 parts by weight of deionized water, adjust the pH to 8.5, then add 1 part by weight of modified ZSM-5 molecular sieve and disperse it ultrasonically for 15 minutes. Then, add 2 parts by weight of the composite bacterial agent and stir at 35°C for 25 hours. After the reaction is completed, a ZSM-5 molecular sieve loaded with composite bacteria is obtained.

[0101] S4.2: 5 parts by weight of fly ash and 1.2 parts by weight of calcium hydroxide were mixed and added to a polytetrafluoroethylene-lined autoclave. The mixture was reacted in a homogeneous reactor at 230°C for 8 hours. After the reaction, the slurry was cooled to room temperature, filtered with filter paper, and washed with deionized water. The product was then dried in an oven to obtain tobermorite.

[0102] S4.3: Add 3 parts by weight of ammonia water, 10 parts by weight of humic acid and 30 parts by weight of water into a sealed reaction tank, heat and stir for 20 minutes to make an ammonium humate solution, then add 40 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20 parts by weight of tobermorite, 5 parts by weight of peat, 5 parts by weight of nano-montmorillonite and 10 parts by weight of liquid sodium silicate into a rotary drum granulator, then add the ammonium humate solution and 17 parts by weight of sepiolite powder, and granulate to obtain a soil conditioner after granulation.

[0103] Planting experiment:

[0104] Soak the tomato seeds in a constant temperature water bath at 45°C for 30 minutes, then sow them in 32-hole seedling trays, with a total of 3 trays. Then select healthy seedlings and plant them in plastic planting pots, with 2 plants per pot. First, fill the pots with a small amount of garden soil, apply organic decomposed chicken manure and triple compound fertilizer as base fertilizer, then mix 40g of soil conditioner with 7kg of garden soil and put them into the planting pots. Water them in time after planting, arrange the planting pots in a solar greenhouse, and manage the field normally.

[0105] The blank control was the one without adding soil conditioner, and the other conditions were the same.

[0106] Soil moisture, water retention, organic matter, and heavy metal content were measured before planting. These were also measured after the tomatoes matured. Growth rates were also measured, along with the number of tomatoes set. The results are shown in Table 1.

[0107] Table 1. Measurement results of soil moisture content, water retention, organic matter content and heavy metal content in Examples 1-3

[0108] Soil moisture content Water retention Organic matter content Heavy metal content Example 1 20.39％ 59.34％ 19.82％ -10.23％ Example 2 19.72％ 58.45％ 19.19％ -9.63％ Example 3 20.17％ 59.12％ 19.72％ -9.247％

[0109] It can be seen from the data in Table 1 that the soil conditioner prepared by the present invention can significantly improve the water content and water retention of the soil, while also increasing the organic matter content in the soil and reducing the heavy metal content in the soil.

[0110] The number of fruit set of the tomatoes planted in the blank control and the number of fruit set of the tomatoes planted in Examples 1-3 were measured, and the change rate of the number of fruit set of the tomatoes planted in Examples 1-3 was calculated. The measurement results are shown in Table 2.

[0111] Table 2. Change rate of fruit set number of tomatoes grown in Examples 1-3

[0112] Change rate of fruit set Example 1 12.1％ Example 2 11.3％ Example 3 11.7％

[0113] From the data in Table 2, it can be seen that the use of soil conditioners can promote the flowering and fruiting of plants.

[0114] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A preparation process of a soil conditioner for soil remediation, characterized in that: The steps include: S1: Synthesis of four-arm star polymers Pentaerythritol succinate is prepared by using pentaerythritol, succinic anhydride and 4-dimethylaminopyridine, then an intermediate product is prepared by using pentaerythritol succinate, polyethylene glycol, dicyclohexylcarbodiimide and 4-dimethylaminopyridine, and then a four-arm star polymer is prepared by using the intermediate product, succinic anhydride and 4-dimethylaminopyridine; S2: Preparation of modified ZSM-5 molecular sieve The ZSM-5 molecular sieve is modified by using a four-arm star polymer to obtain a modified ZSM-5 molecular sieve; S3: Preparation of compound bacterial agent Brevibacillus laterosporus, Bacillus subtilis and Bacillus licheniformis are cultured and fermented to prepare a composite bacterial agent; S4: Preparation of soil conditioner 40-50 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20-30 parts by weight of tobermorite, 5-8 parts by weight of peat, 5-8 parts by weight of nano-montmorillonite and 10-12 parts by weight of liquid sodium silicate are added to a rotary drum granulator, and then an ammonium humate solution and 17-20 parts by weight of sepiolite powder are added to prepare a soil conditioner.

2. The preparation process of a soil conditioner for soil remediation according to claim 1, characterized in that: Step S1: Synthesis of a four-arm star polymer, specifically comprising the following steps: S1.1: Add 0.1-0.2 parts by weight of pentaerythritol, 0.6-1 parts by weight of succinic anhydride, and 0.6-1 parts by weight of 4-dimethylaminopyridine to 20-23 parts by weight of N,N-dimethylformamide, and stir the mixture at 60-65°C under a nitrogen atmosphere for 25-25 hours. After the reaction is completed, perform vacuum distillation at 70-75°C to obtain a mixed product, dissolve the mixed product in 20-30 parts by weight of a CH2Cl2 solution, extract the mixture with 1 mol / L dilute hydrochloric acid, and wash the mixture 2-3 times with deionized water. Dry the washed product to obtain pentaerythritol succinate; S1.2: 0.1-0.2 parts by weight of pentaerythritol succinate, 0.7-1 parts by weight of polyethylene glycol, 0.6-0.8 parts by weight of dicyclohexylcarbodiimide, and 0.6-0.8 parts by weight of 4-dimethylaminopyridine are added to 20-23 parts by weight of N,N-dimethylformamide, and stirred at 120-125°C under a nitrogen atmosphere for 25-25 hours. After the reaction is completed, 100-120 parts by weight of deionized water are added to the product, and the product is vacuum filtered and rotary evaporated. The crude product is extracted with 1 mol / L dilute hydrochloric acid and CHCl, and then washed 2-3 times with 10% NaCl solution. Finally, the organic phase is precipitated with diethyl ether and dried under vacuum at 50-60°C overnight to obtain an intermediate product; S1.3: Add 0.1-0.2 parts by weight of the intermediate product, 0.6-1 parts by weight of succinic anhydride and 0.6-1 parts by weight of 4-dimethylaminopyridine to 20-23 parts by weight of N,N-dimethylformamide and stir the mixture at 60-65°C in a nitrogen atmosphere for 25-25 hours. After the reaction is completed, perform reduced pressure distillation at 70-75°C to obtain a mixed product. Dissolve the mixed product in 20-30 parts by weight of CH2Cl2 solution, extract with 1 mol / L dilute hydrochloric acid, and wash with deionized water 2-3 times. Dry the washed product to obtain a four-arm star polymer.

3. The preparation process of a soil conditioner for soil remediation according to claim 2, characterized in that: Step S2: Preparation of modified ZSM-5 molecular sieve, specifically comprising the following steps: S2.1: Dissolve 20-30 parts by weight of sodium hydroxide in 100-120 parts by weight of deionized water, then add 10-20 parts by weight of silica sol containing 25% silicon dioxide and 2-5 parts by weight of sodium aluminate, and stir at 200-300 rpm for 20-30 hours to obtain a mixed solution; S2.2: Transfer the mixed solution to a reactor and heat at 180-200°C for 24-25 hours. After the reaction is complete, separate the product by vacuum filtration and wash it with deionized water several times until the supernatant becomes a neutral solution. Dry the product to obtain ZSM-5 molecular sieve. S2.3: Add the obtained ZSM-5 molecular sieve to a mixed solvent of 20-30 parts by weight of ethanol, 5-8 parts by weight of deionized water, and 0.7-1 parts by weight of ammonium hydroxide, and ultrasonically disperse for 20-30 minutes. Then, add 0.3-0.5 parts by weight of KH-792, and react at 60-65°C for 20-24 hours. After the reaction is completed, wash with ethanol and deionized water 3-5 times respectively, and centrifuge and dry to obtain NH2-ZSM-5 molecular sieve; S2.4: Dissolve 8-10 parts by weight of a four-arm star polymer, 3-5 parts by weight of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and 2-3 parts by weight of 4-dimethylaminopyridine in 50-80 parts by weight of N,N-dimethylformamide solution to obtain a mixed solution, disperse 4-5 parts by weight of NH2-ZSM-5 molecular sieve in the mixed solution, stir at 60-65°C under a nitrogen atmosphere for 24-25 hours, and after the reaction is completed, dissolve the product in 20-30 parts by weight of a CH2Cl2 solution, then extract with 1 mol / L dilute hydrochloric acid, and wash with deionized water 2-3 times. Dry the washed product to obtain a modified ZSM-5 molecular sieve.

4. The preparation process of a soil conditioner for soil remediation according to claim 3, characterized in that: Step S3: Preparation of the composite bacterial agent, specifically comprising the following steps: S3.1: Inoculating Brevibacillus laterosporus, Bacillus subtilis, and Bacillus licheniformis into seed culture medium for cultivation, respectively, to obtain Brevibacillus laterosporus seed solution, Bacillus subtilis seed solution, and Bacillus licheniformis seed solution; S3.2: Combine sucrose, lactose, maltose, soluble starch, peptone, yeast extract, urea, NaCl, K2SO4, K2HPO4, MgSO4·7H2O, CaCl2, CaCO3, and water, adjust the pH to 8.0, sterilize at 121°C for 45-50 minutes, and cool to 34°C to obtain a culture medium; S3.3: Mix the seed liquid of Brevibacillus laterosporus, the seed liquid of Bacillus subtilis, and the seed liquid of Bacillus licheniformis at a ratio of 1:1:1 to obtain a mixed seed liquid, add the mixed seed liquid into a fermentation tank at a ratio of 5% of the volume of the culture medium, and culture at 35°C with oxygen and stirring for 16-20 hours to obtain a composite bacterial agent.

5. The preparation process of a soil conditioner for soil remediation according to claim 4, characterized in that: The components of the culture medium in S3.2 are sucrose 15%, lactose 12%, maltose 5%, soluble starch 5%, peptone 15%, yeast extract 9%, urea 5%, NaCl 8%, K2SO4 1.0%, K2HPO4 1.5%, MgSO4·7H2O 3.5%, CaCl2 1.5%, CaCO3 6.5%, and the balance is water.

6. The preparation process of a soil conditioner for soil remediation according to claim 5, characterized in that: Step S4: Preparation of soil conditioner, specifically comprising the following steps: S4.1: Dissolve 1-2 parts by weight of tris(hydroxymethyl)aminomethane hydrochloride in 50-60 parts by weight of deionized water, adjust the pH to 8.5, then add 1-2 parts by weight of modified ZSM-5 molecular sieve and ultrasonically disperse for 10-15 minutes. Then, add 2-3 parts by weight of the composite bacterial agent and stir at 32-35°C for 24-25 hours. After the reaction is completed, a ZSM-5 molecular sieve loaded with composite bacteria is obtained. S4.2: 5-10 parts by weight of fly ash and 1.2-2 parts by weight of calcium hydroxide are mixed and added to a polytetrafluoroethylene-lined autoclave. The mixture is reacted in a homogeneous reactor at 200-230°C for 6-8 hours. After the reaction is completed, the slurry is cooled to room temperature, filtered with filter paper, and washed with deionized water. The product is then dried in an oven to obtain tobermorite; S4.3: Add 2-3 parts by weight of ammonia water, 10-15 parts by weight of humic acid and 30-40 parts by weight of water to a sealed reaction tank, heat and stir for 15-20 minutes to prepare an ammonium humate solution, then add 40-50 parts by weight of ZSM-5 molecular sieve loaded with composite bacteria, 20-30 parts by weight of tobermorite, 5-8 parts by weight of peat, 5-8 parts by weight of nano-montmorillonite and 10-12 parts by weight of liquid sodium silicate to a rotary drum granulator, then add the ammonium humate solution and 17-20 parts by weight of sepiolite powder, and granulate to obtain a soil conditioner after granulation.

7. A soil conditioner for soil remediation, characterized in that: The soil conditioner is prepared by the preparation process of a soil conditioner for soil remediation according to any one of claims 1 to 6.

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