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CN-122010632-A - Fertilizer for reducing cadmium ion absorption of crops and preparation method thereof

CN122010632ACN 122010632 ACN122010632 ACN 122010632ACN-122010632-A

Abstract

The invention relates to the technical field of fertilizers, in particular to a fertilizer for reducing cadmium ion absorption of crops and a preparation method thereof. A preparation method of a fertilizer for reducing cadmium ion absorption of crops comprises the steps of preparing sulfhydryl modified LDH, preparing activated biochar and preparing a compound fertilizer. According to the invention, magnesium nitrate hexahydrate and aluminum nitrate nonahydrate are dissolved to form a mixed salt solution, then sodium hydroxide solution is added to generate coprecipitation reaction to generate MgLDH lamellar precursor, then 3-mercaptopropyl trimethoxy silane is added to graft mercapto groups on the surface of an LDH lamellar structure through silane coupling, and then hydrothermal crystallization reaction is carried out at 120-130 ℃ to realize stable loading of mercapto groups, so that the mercapto modified LDH with lamellar structure and strong cadmium adsorption performance is finally formed, and after the mercapto modified LDH is added into fertilizer, the bioavailability of cadmium ions in soil can be obviously reduced, and further the absorption of cadmium ions by crop root systems and the transportation to overground parts are effectively reduced.

Inventors

  • LI SHANSHAN
  • YANG BING
  • FEI YANG
  • QI JINGXIAN
  • SHI HUADING

Assignees

  • 生态环境部土壤与农业农村生态环境监管技术中心

Dates

Publication Date
20260512
Application Date
20260311

Claims (8)

  1. 1. A method for preparing a fertilizer for reducing cadmium ion absorption of crops, which is characterized by comprising the following steps: S1 preparation of thiol-modified LDH Dissolving magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water, and then adding sodium hydroxide solution and 3-mercaptopropyl trimethoxy silane for hydrothermal reaction to obtain mercapto-modified LDH; S2, preparing activated biochar Cleaning, drying, crushing and pyrolyzing rice hulls, and then soaking the rice hulls in potassium hydroxide solution for activation to obtain activated biochar; S3, preparing the compound fertilizer Adding the sulfhydryl modified LDH, the activated biochar, urea, diammonium phosphate, potassium sulfate, humic acid and a binder into a double-screw conical mixer, adding 6-8wt% of deionized water, stirring and mixing uniformly, adding a compound microbial agent, continuing stirring and mixing for 5-10min, and granulating, drying and screening to obtain the compound fertilizer.
  2. 2. The method for preparing the fertilizer for reducing cadmium ion absorption of crops according to claim 1, wherein the fertilizer comprises the following raw materials, by mass, 18-22 parts of sulfhydryl modified LDH, 20-25 parts of activated biochar, 6-8 parts of urea, 10-12 parts of diammonium phosphate, 2-3 parts of potassium sulfate, 8-10 parts of humic acid, 1-2 parts of binder and 3-5 parts of composite microbial agent.
  3. 3. The method for preparing fertilizer for reducing cadmium ion absorption of crops according to claim 2, wherein the binder is sodium carboxymethyl cellulose.
  4. 4. The preparation method of the fertilizer for reducing cadmium ion absorption of crops according to claim 2, wherein the compound microbial agent is prepared by compounding bacillus subtilis, bacillus mucilaginosus and saccharomyces cerevisiae according to the mass ratio of (2-3) (1.4-1.6) to 1.
  5. 5. The method for preparing fertilizer for reducing cadmium ion absorption by crops according to claim 1, wherein S1 comprises the steps of: s1.1, adding magnesium nitrate hexahydrate and aluminum nitrate nonahydrate into deionized water according to the ratio of (1.3-1.4) g to 1g (10-12) mL, and fully stirring until the magnesium nitrate hexahydrate and the aluminum nitrate nonahydrate are dissolved to obtain a mixed salt solution; S1.2, adding 2mol/L sodium hydroxide solution into the mixed salt solution under the protection of nitrogen, regulating the pH to 9, adding 3-mercaptopropyl trimethoxy silane while stirring, continuously stirring for 30-40min, transferring into a hydrothermal kettle, carrying out hydrothermal crystallization for 10-12h at 120-130 ℃, cooling, and carrying out suction filtration, washing with deionized water to be neutral, vacuum drying and grinding to obtain the mercapto-modified LDH.
  6. 6. The method for preparing fertilizer for reducing cadmium ion absorption by crops according to claim 5, wherein the addition amount of 3-mercaptopropyl trimethoxysilane is 1.8-2% of the volume of the mixed salt solution.
  7. 7. The method for preparing fertilizer for reducing cadmium ion absorption by crops according to claim 1, wherein S2 comprises the steps of: S2.1, cleaning rice hulls, drying the rice hulls to constant weight at 100-110 ℃, crushing the rice hulls, and sieving the crushed rice hulls with a 40-mesh sieve to obtain rice hull powder; S2.2, performing anoxic pyrolysis on the rice hull powder for 2-3 hours at 600-700 ℃, adding the rice hull powder into a 2mol/L potassium hydroxide solution, soaking for 8-10 hours, and filtering, washing to be neutral and drying to obtain activated biochar.
  8. 8. A fertilizer for reducing cadmium ion absorption by crops, characterized in that it is prepared by a method for preparing a fertilizer for reducing cadmium ion absorption by crops according to any one of claims 1 to 7.

Description

Fertilizer for reducing cadmium ion absorption of crops and preparation method thereof Technical Field The invention relates to the technical field of fertilizers, in particular to a fertilizer for reducing cadmium ion absorption of crops and a preparation method thereof. Background Cadmium is a heavy metal element with strong biological toxicity, is easy to enrich in soil and difficult to degrade, becomes one of main pollutants of farmland soil in China, and seriously threatens the quality safety and human health of agricultural products. At present, various farmland in China has cadmium pollution, crops planted in polluted soil are easy to absorb cadmium ions in soil, and then the cadmium ions accumulate in seeds, stems and leaves, and after the cadmium ions enter human bodies through food chains, the cadmium ions can cause continuous damage to organs such as kidneys, bones and the like. At present, the treatment strategies aiming at the soil cadmium pollution mainly comprise physical engineering repair, chemical passivation repair and agronomic regulation measures. Physical repair such as soil-alien method or deep ploughing is thorough in effect, but large in engineering quantity and high in cost, and the original soil structure can be damaged. Agronomic measures such as moisture management or variety screening, although reducing cadmium absorption to some extent, are limited by natural conditions and variety characteristics, have poor operability and are difficult to be used as a solution for universality. The chemical passivation repair is mainly carried out by applying lime, a calcium silicate substance or a phosphate material, so as to improve the pH value of soil or form precipitation with cadmium ions, thereby reducing the effective state content of the calcium silicate in the soil. However, these traditional passivating agents tend to have a single function, only concern about immediate fixation of cadmium in soil, neglect the absorption process of crop root systems to nutrients and the transport mechanism of cadmium in plants, and have unstable effect of partial passivating agents in acidic environment, and have the risk of secondary release. Therefore, a fertilizer capable of reducing cadmium ion absorption of crops and a preparation method thereof are needed. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a fertilizer for reducing cadmium ion absorption of crops and a preparation method thereof. The invention provides a preparation method of a fertilizer for reducing cadmium ion absorption of crops, which comprises the following steps: S1 preparation of thiol-modified LDH Dissolving magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water, and then adding sodium hydroxide solution and 3-mercaptopropyl trimethoxy silane for hydrothermal reaction to obtain mercapto-modified LDH; S2, preparing activated biochar Cleaning, drying, crushing and pyrolyzing rice hulls, and then soaking the rice hulls in potassium hydroxide solution for activation to obtain activated biochar; S3, preparing the compound fertilizer Adding the sulfhydryl modified LDH, the activated biochar, urea, diammonium phosphate, potassium sulfate, humic acid and a binder into a double-screw conical mixer, adding 6-8wt% of deionized water, stirring and mixing uniformly, adding a compound microbial agent, continuing stirring and mixing for 5-10min, and granulating, drying and screening to obtain the compound fertilizer. Further, the compound fertilizer comprises, by mass, 18-22 parts of sulfhydryl modified LDH, 20-25 parts of activated biochar, 6-8 parts of urea, 10-12 parts of diammonium phosphate, 2-3 parts of potassium sulfate, 8-10 parts of humic acid, 1-2 parts of binder and 3-5 parts of compound microbial agent. Further, the binder is sodium carboxymethyl cellulose. Further, the compound microbial agent is prepared by compounding bacillus subtilis, bacillus mucilaginosus and saccharomyces cerevisiae according to the mass ratio of (2-3) (1.4-1.6): 1. Further, S1 includes the following steps: s1.1, adding magnesium nitrate hexahydrate and aluminum nitrate nonahydrate into deionized water according to the ratio of (1.3-1.4) g to 1g (10-12) mL, and fully stirring until the magnesium nitrate hexahydrate and the aluminum nitrate nonahydrate are dissolved to obtain a mixed salt solution; S1.2, adding 2mol/L sodium hydroxide solution into the mixed salt solution under the protection of nitrogen, regulating the pH to 9, adding 3-mercaptopropyl trimethoxy silane while stirring, continuously stirring for 30-40min, transferring into a hydrothermal kettle, carrying out hydrothermal crystallization for 10-12h at 120-130 ℃, cooling, and carrying out suction filtration, washing with deionized water to be neutral, vacuum drying and grinding to obtain the mercapto-modified LDH. Further, the addition amount of the 3-mercaptopropyl trimethoxysilane is 1.8-2% of the volume of the