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CN-121991698-A - Pb-polluted soil curing agent and preparation method thereof

CN121991698ACN 121991698 ACN121991698 ACN 121991698ACN-121991698-A

Abstract

The invention discloses a Pb-polluted soil curing agent and a preparation method thereof, and belongs to the technical field of environmental repair materials. The method comprises the steps of preparing functional natural lysine powder through glutaraldehyde crosslinking and phosphorylation treatment of lysine, mixing and grinding calcium magnesium phosphate and magnesium oxide to prepare a composite phosphate matrix, carrying out a load reaction on the functional lysine powder and a composite phosphate matrix aqueous solution, obtaining a precursor after treatment, mixing and granulating the precursor, starch and sodium carboxymethyl cellulose, and drying to finally prepare the spherical soil curing agent. According to the invention, natural lysine is used as a functional source, an organic solvent or toxic chemicals are not required, the preparation process is simple and convenient, the large-scale production is easy, the environment restoration requirements of greenization, low carbonization and resource are met, and the Pb content in the polluted soil can be obviously reduced by using the curing agent for restoring Pb polluted soil.

Inventors

  • HU YANDI
  • LI SHIYU
  • JIANG XULIN
  • HUANG JIANHONG

Assignees

  • 北京大学
  • 昆明理工大学

Dates

Publication Date
20260508
Application Date
20260119

Claims (10)

  1. 1. The preparation method of the Pb-polluted soil curing agent is characterized by comprising the following steps of: s1, preparing functionalized natural lysine: ① Crosslinking treatment, namely adding glutaraldehyde water solution into lysine water solution, adjusting pH, and stirring for reaction to obtain crosslinked lysine solution; ② Phosphorylation treatment, namely adding NaH 2 PO 4 ·2H 2 O solid powder into the crosslinked lysine solution, adjusting pH, heating for reaction, filtering, washing and vacuum drying after the reaction is finished to obtain functional natural lysine powder; S2, preparing a phosphate matrix, namely mixing and grinding Ca (H 2 PO 4 ) 2 ·H 2 O、CaHPO 4 ·2H 2 O and MgHPO 4 ·3H 2 O), sieving to obtain a calcium magnesium phosphate matrix, adding magnesium oxide into the calcium magnesium phosphate matrix, mixing and grinding uniformly to obtain a composite phosphate matrix, and sealing and storing; S3, loading the functionalized lysine, namely preparing a composite phosphate matrix into a composite phosphate matrix aqueous solution, adding functionalized natural lysine powder into the composite phosphate matrix aqueous solution, adjusting pH, carrying out loading reaction, filtering after the reaction is finished, and drying in vacuum to obtain precursor powder; S4, preparing a pellet curing agent, namely uniformly mixing precursor powder, starch and sodium carboxymethyl cellulose to obtain a mixed dry material, adding water into the mixed dry material, stirring the mixed dry material to form a wet material, granulating the wet material to obtain wet pellets, and drying the wet pellets to obtain Pb-polluted soil curing agent pellets.
  2. 2. The method for preparing a Pb contaminated soil curing agent according to claim 1, wherein the concentration of the lysine aqueous solution in the crosslinking treatment in step S1 is 8% -12% by mass, the concentration of the glutaraldehyde aqueous solution is 20% -30% by mass, and the volume ratio of the lysine aqueous solution to the glutaraldehyde aqueous solution is 20:1.
  3. 3. The method for preparing a Pb-contaminated soil solidifying agent according to claim 1, wherein the condition for adjusting the pH in the step S1 of the cross-linking treatment is that an aqueous solution of NaH 2 PO 4 with a mass percent concentration of 8-12% is used for adjusting the pH to 8.0, and the condition for the stirring reaction is that the stirring reaction is carried out for 2 hours at 40-60 ℃.
  4. 4. The method for preparing a Pb contaminated soil curing agent according to claim 1, characterized in that the mass ratio of NaH 2 PO 4 ·2H 2 O solid powder to lysine in the crosslinked lysine solution in the step S1 phosphorylation is 1:5-10.
  5. 5. The method for preparing the Pb-contaminated soil curing agent according to claim 1, wherein the pH-adjusting condition in the step S1 of phosphorylation is that NaH 2 PO 4 aqueous solution with the mass percent concentration of 8% -12% is used for adjusting the pH to 6.5-7.0, the heating reaction is that the reaction is carried out at 50-70 ℃ for 2-3h, the washing condition is that deionized water is used for 3-5 times, and the vacuum drying condition is that the vacuum drying is carried out at 50-70 ℃ for 10-12h under the vacuum degree of 0.006-0.015 MPa.
  6. 6. The method for preparing the Pb-contaminated soil solidifying agent according to claim 1, wherein in the step S2, the mass ratio of Ca (H 2 PO 4 ) 2 ·H 2 O、CaHPO 4 ·2H 2 O to MgHPO 4 ·3H 2 O) is 2:2:1, the mass ratio of the calcium magnesium phosphate matrix to the magnesium oxide is 5:1, and the granularity of the calcium magnesium phosphate matrix is 100-300 meshes.
  7. 7. The method for preparing the Pb-contaminated soil solidifying agent according to claim 1, wherein the mass percentage concentration of the composite phosphate matrix aqueous solution in the step S3 is 20% -30%, and the mass ratio of the functionalized natural lysine powder to the composite phosphate matrix in the composite phosphate matrix aqueous solution is 20:1-3.
  8. 8. The method for preparing a Pb-contaminated soil solidifying agent according to claim 1, wherein the condition for adjusting the pH in the step S3 is that an aqueous NaH 2 PO 4 solution with a mass percentage concentration of 8% -12% is used for adjusting the pH to 6.5-7.5, the condition for carrying out the reaction is that stirring is carried out for 2 hours at 50-70 ℃ and then standing is carried out for 1 hour at 50 ℃, and the condition for vacuum drying is that vacuum drying is carried out for 6-10 hours at 50-70 ℃ under a vacuum degree of 0.006-0.015 MPa.
  9. 9. The preparation method of the Pb-contaminated soil solidifying agent according to claim 1, wherein in the step S4, the mass ratio of the lysine-loaded phosphate solidifying agent precursor powder to the starch to the sodium carboxymethylcellulose is 20:2:1, the moisture content of the wet material is 20-35wt%, the granulating condition is that granulating is carried out under the conditions that the rotating speed is 15-20rpm and the inclination angle is 45 ℃, the diameter of the wet pellets is 2.0-3.0mm, and the drying condition is that drying is carried out for 6 hours under the conditions that the drying temperature is 80-120 ℃.
  10. 10. The Pb contaminated soil solidifying agent prepared by the method of any one of claims 1 to 9.

Description

Pb-polluted soil curing agent and preparation method thereof Technical Field The invention relates to the technical field of environmental remediation materials, in particular to a Pb-polluted soil curing agent and a preparation method thereof. Background Lead (Pb), a typical heavy metal contaminant, is emitted in large amounts during mining, smelting, battery manufacturing, paint, and traffic exhaust, resulting in a general rise in lead content in the soil. Lead has high toxicity, durability and bioaccumulation in the environment, can enter human body through food chain, and causes serious harm to nervous system, blood system and children intelligence development. Therefore, how to efficiently, economically and environmentally friendly fix and stabilize the movable Pb in the soil is a research hotspot and technical difficulty in the current soil remediation field. The existing Pb-polluted soil curing/stabilizing treatment technology mainly comprises an inorganic curing method, an organic adsorption method and a composite curing method, wherein a single phosphate system is prone to the problems of low reaction rate, poor compactness of a curing layer, insufficient long-term stability and the like in actual soil, secondary dissolution is easy to occur in a low pH or complex ion environment, and on the other hand, conventional organic curing materials (such as humic acid, amino acid and the like) have metal ion complexing capability, but are easy to degrade in soil, poor in durability and difficult to maintain a curing effect for a long time. However, in most researches on organic-inorganic composite cured materials, the organic modifier used generally has the problems of complicated synthesis steps, high cost or poor environmental compatibility, which greatly limits the engineering application and popularization of the technology. Therefore, the material which has the dual functions of efficient adsorption and stable precipitation and has the important significance as the curing agent is developed, and the material has the advantages of simple preparation process, low cost and environmental friendliness. Disclosure of Invention In order to solve the problems of insufficient stability, easy dissolution, easy degradation, difficult persistence, high cost, complex process and restricted engineering application of an organic method in the existing method, the invention aims to provide a preparation method of Pb-polluted soil curing agent. The method specifically comprises the following steps: s1, preparing functionalized natural lysine: ① And (3) crosslinking treatment, namely adding glutaraldehyde water solution into the lysine water solution, adjusting pH, and stirring for reaction to obtain a crosslinked lysine solution. ② And (3) phosphorylation treatment, namely adding NaH 2PO4·2H2 O solid powder into the crosslinked lysine solution, adjusting the pH value, heating for reaction, filtering, washing and drying in vacuum after the reaction is finished to obtain the functionalized natural lysine powder. S2, preparing a phosphate matrix, namely mixing and grinding Ca (H 2PO4)2·H2O、CaHPO4·2H2 O and MgHPO 4·3H2 O), sieving to obtain a calcium magnesium phosphate matrix, adding magnesium oxide into the calcium magnesium phosphate matrix, mixing and grinding uniformly to obtain a composite phosphate matrix, and sealing and storing. S3, loading the functionalized lysine, namely preparing a composite phosphate matrix into a composite phosphate matrix aqueous solution, adding functionalized natural lysine powder into the composite phosphate matrix aqueous solution, adjusting pH, carrying out loading reaction, filtering after the reaction is finished, drying in vacuum, grinding and screening to obtain precursor powder. S4, preparing a pellet curing agent, namely uniformly mixing precursor powder, starch and sodium carboxymethyl cellulose to obtain a mixed dry material, adding water into the mixed dry material, stirring the mixed dry material to form a wet material, granulating the wet material to obtain wet pellets, and drying the wet pellets to obtain Pb-polluted soil curing agent pellets. Preferably, the concentration of the lysine aqueous solution in the step S1 crosslinking treatment is 8-12% by mass. Preferably, the concentration of glutaraldehyde aqueous solution in the step S1 crosslinking treatment is 20-30% by mass. Preferably, the volume ratio of the lysine aqueous solution to the glutaraldehyde aqueous solution in the step S1 crosslinking treatment is 20:1. Preferably, the condition for adjusting the pH in the step S1 crosslinking treatment is that an aqueous solution of NaH 2PO4 with the mass percent concentration of 8-10% is used for adjusting the pH to 8.0. Preferably, the condition of stirring reaction in the step S1 crosslinking treatment is that stirring reaction is carried out for 2 hours at 40-60 ℃. Preferably, the mass ratio of NaH 2PO4·2H2 O solid powder to lysine in the crosslinked lysine solution