A material for improving soil conductivity of a substation and a method of manufacturing the same

Abstract

The application discloses a material for improving soil conductivity of a transformer substation and a preparation method thereof, and the preparation method comprises the following steps: adding a polyacrylate copolymer into triethylenetetramine, performing a temperature rising reaction, soaking in a hydrochloric acid solution, adjusting pH, washing with deionized water, extracting with acetone, and obtaining a polyacrylate chelating resin; mixing and stirring the polyacrylate chelating resin, a crosslinking agent, straw biochar and deionized water to obtain biochar modified polyacrylate chelating resin; and mixing 20-35 parts of vermiculite, 2-4 parts of hydroxyapatite, 10-15 parts of bentonite, 25-35 parts of quicklime, 15-20 parts of biochar modified polyacrylate chelating resin and 30-40 parts of corn straw. The material prepared by the application can effectively reduce the content of heavy metals in soil and form stable chelation products, can reduce the water content of soil, can improve the resistivity of soil, can reduce the conductivity of soil, and can further realize the protection of equipment of the transformer substation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of soil remediation, and particularly relates to a material for improving the soil conductivity of a transformer substation and a preparation method thereof. BACKGROUND

[0002] In a soil system, the soil can be regarded as a kind of multivalent electrolyte because the soil particles carry electric charges and adsorb a certain amount of ions of opposite signs, so the soil system will also have the phenomenon of electric conduction under the action of an applied electric field. The electric conduction performance of the soil is mainly determined by the number of charged particles, and the content of heavy metals in the soil and the water content of the soil are two important influencing factors.

[0003] The waste lead-acid batteries and discarded electric power equipment generated by production activities in a transformer substation are stored and leaked, leading to the formation of heavy metal pollution in the soil of the transformer substation, especially serious pollution of chromium and copper. The decrease of the electric resistance performance of the soil causes great threat to the safety of personnel and equipment in the transformer substation. Therefore, it is urgent to develop a material for improving the content of heavy metals in the soil and the water content of the soil, so as to improve the soil resistivity and achieve the effect of protecting personnel and equipment.

[0004] At present, for the heavy metal pollution of soil, the common method is to add ion exchange resin to combine with metal ions by electrostatic action, but in practical application, there are some disadvantages such as limited exchange capacity, microbial proliferation on the surface of the resin, and easy dissolution of organic matter in the resin. The traditional chelating resin mostly uses polystyrene as the skeleton, so it has the defects of poor hydrophilicity, poor resistance to organic pollution, and low secondary recycling rate. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a material for improving the soil conductivity of a transformer substation and a preparation method thereof. The prepared material can not only effectively reduce the content of heavy metals in the soil and form stable chelate products, but also reduce the water content of the soil, thereby improving the soil resistivity, reducing the soil electric conduction performance, and achieving the protection of the equipment in the transformer substation.

[0006] The present application provides the following technical solutions:

[0007] In a first aspect, a material for improving the soil conductivity of a transformer substation is provided, which comprises the following raw materials by weight: 20-35 parts of vermiculite, 2-4 parts of hydroxyapatite, 10-15 parts of bentonite, 25-35 parts of quicklime, 15-20 parts of biochar modified polyacrylate chelating resin, and 30-40 parts of corn straw.

[0008] Further, the biochar modified polyacrylate chelating resin comprises the following raw materials by weight: polyacrylate chelating resin 80-90 parts, divinyl benzene crosslinking agent 0.3-0.5 parts, straw biochar 0.8-1.2 parts, and deionized water 120 parts.

[0009] In a second aspect, a preparation method of the material for improving the soil conductivity of a transformer substation is provided, and the method comprises the following steps:

[0010] The straw core is not separated and crushed, and then soaked in an activator, followed by drying, activation, detergent washing, water washing, pH adjustment, drying, grinding, and screening to obtain the straw biochar.

[0011] The polyacrylate copolymer is added to triethylene tetramine, and the reaction is maintained by heating, then fully soaked and stirred in a hydrochloric acid solution, the pH is adjusted to neutral, and then washed with deionized water and extracted with acetone to obtain the polyacrylate chelating resin.

[0012] The polyacrylate chelating resin, crosslinking agent, straw biochar, and deionized water are mixed and stirred uniformly to obtain the biochar modified polyacrylate chelating resin.

[0013] The biochar modified polyacrylate chelating resin, vermiculite, hydroxyapatite, bentonite, quicklime, and corn straw are mixed and stirred uniformly to obtain the material for improving the soil conductivity of a transformer substation.

[0014] Further, the activator is a zinc chloride solution, the activation temperature is 500-600℃, and the activation time is 70-90min.

[0015] Further, the detergent is a hydrochloric acid solution with a mass fraction of 10%, and the particle size of the ground product after screening is 80% through a 200-mesh screen.

[0016] Further, the preparation method of the polyacrylate copolymer comprises the following steps: dissolving an emulsifier in deionized water, then adding mixed monomers, stirring and heating to raise the temperature, adding an initiator in batches to complete the polymerization reaction, and adjusting the pH to neutral after cooling to room temperature.

[0017] Further, the emulsifier is a composite emulsifier system composed of sorbitol ester span-20, octyl phenol polyoxyethylene-10, and sodium dodecyl sulfate with a mass ratio of 2.3:1:0.9, the mixed monomers include ethyl acrylate and butyl acrylate with a molar ratio of (0.5-2):1, the initiator is ammonium persulfate, and the mass ratio of the mixed monomers, emulsifier, and initiator is 100:(1.5-3):(0.6-0.7).

[0018] Further, the temperature of the polymerization reaction is 80-95 DEG C.

[0019] Further, the polyacrylate copolymer is mixed with triethylene tetramine in a mass ratio (2-4):1, heated to 65-85 DEG C and maintained for 2.5-3 hours, and then fully immersed and stirred with 2 mol / L hydrochloric acid solution.

[0020] Further, the preparation method of the hydroxyapatite comprises:

[0021] According to the ratio of n(Ca):n(P) of hydroxyapatite 5:3=1.67, calcium nitrate tetrahydrate and diammonium hydrogen phosphate are weighed respectively, and calcium nitrate solution and diammonium hydrogen phosphate solution are prepared;

[0022] The diammonium hydrogen phosphate solution is added to the calcium nitrate tetrahydrate, constant temperature stirring is carried out, ammonia water is added to adjust the pH value to 10-10.5, then aging, washing, drying, grinding and sintering are carried out to obtain the hydroxyapatite powder.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] (1) The biochar modified polyacrylate chelating resin in the application is a high hydrophilic chelating resin with a semi-EDTA type structure synthesized by straw biochar modification; first, it can coordinate with metal ions to produce coordinate covalent bonds and form a stable chelate product, so it has strong binding ability with metal ions, high selectivity, good heavy metal (especially Cu and Cr) adsorption effect, and can improve the soil resistivity and reduce the soil conductivity; second, the use of straw biochar can solve a series of problems such as biomass energy waste and environmental pollution caused by crop straw burning to a great extent, and the aforementioned chelate product can be naturally degraded, and the degraded biochar is beneficial to maintaining and improving soil quality; third, the biochar modified polyacrylate chelating resin of the application also has the characteristics of fast adsorption and desorption speed, high desorption rate and strong regeneration ability, which improves the defects of traditional chelating resins such as poor hydrophilicity, poor resistance to organic pollution and low secondary recycling rate.

[0025] (2) The quicklime in the application can reduce the water content of the soil, thereby achieving the effects of improving the soil resistivity and reducing the soil conductivity; the vermiculite can adsorb and fix the heavy metal ions in the soil through ion exchange and surface complexation; the hydroxyapatite is used for absorbing the water in the soil to reduce the water content and reduce the bioavailability of Pb, Cd, Cu and Zn in the soil; the bentonite has a passivation effect on Cr and Cu in the soil; and the corn straw provides the porous biochar with high porosity, large specific surface area and good adsorption of the free heavy metal ions in the soil. DETAILED DESCRIPTION

[0026] The following examples are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0027] Example 1

[0028] The present embodiment provides a preparation method of a material for improving the soil conductivity of a transformer substation, and the steps are as follows:

[0029] (1) Preparation of hydroxyapatite.

[0030] According to the n(Ca):n(P) ratio of 5:3 = 1.67 of the hydroxyapatite, 11.1 g of calcium nitrate tetrahydrate and 3.72 g of diammonium hydrogen phosphate are weighed respectively; the calcium nitrate tetrahydrate is dissolved in ultrapure water and stirred and mixed, then excess ammonia water is added to make the pH value of the solution above 11 and sealed to obtain a calcium nitrate solution; the diammonium hydrogen phosphate is dissolved in anhydrous ethanol and stirred and mixed, then a dispersant polyethylene glycol (mass concentration 3%) is added and stirred to dissolve it to obtain a diammonium hydrogen phosphate solution.

[0031] The temperature of the water bath is set to 40℃, the calcium nitrate solution is placed in the 40℃ water bath, after a period of time, the diammonium hydrogen phosphate solution is slowly added into the calcium nitrate solution, while stirring quickly, ammonia water is continuously added to adjust the pH value to 10-10.5, after 2h of sufficient stirring, it is placed in the water bath, the temperature of the water bath is adjusted to 50℃ for aging, and the aging is performed for 24 hours, then it is filtered, washed with deionized water, and washed with alcohol for 3-4 times; the obtained solid is placed in a crucible and dried in a drying box at 120℃ for 2h, then it is taken out and ground with a agate mortar to obtain a superfine powder, which is sintered in a sintering furnace for 2h, the sintering temperature is 800℃, and a bright white hydroxyapatite powder is obtained.

[0032] (2) Preparation of straw biochar.

[0033] The corn straw core is not separated and crushed, 3 mol / L zinc chloride solution is added, soaked at room temperature for 24 h, and then dried at 80℃. After drying, it is put into a crucible and activated at 600℃ for 70 min. The product is washed with 10% dilute hydrochloric acid solution, washed with water, adjusted to pH = 7, dried, ground and sieved to a particle size of 80% passing through a 200 mesh sieve to obtain straw biochar.

[0034] (3) Preparation of biochar modified polyacrylate chelating resin.

[0035] A composite emulsifier is prepared by mixing span-20, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate in a mass ratio of 2.3:1:0.9. The composite emulsifier is dissolved in deionized water, and then a mixture of ethyl acrylate and butyl acrylate monomers in a molar ratio of 2:1 is added. The mixture is heated and stirred to 80℃, and ammonium persulfate with a mass fraction of 0.5% is added as a reaction initiator. The mass ratio of the mixed monomers, composite emulsifier and initiator is 100:1.5:0.6. After the polymerization is completed, the mixture is cooled to room temperature for 60 min, and the pH is adjusted to 7 to obtain a polyacrylate copolymer.

[0036] The obtained polyacrylate copolymer is mixed with triethylenetetramine in a mass ratio of 4:1, heated to 65℃ and maintained for 3h. Then it is fully soaked and stirred with 2 mol / L hydrochloric acid solution, the pH is adjusted to neutral, and then washed with deionized water and extracted with acetone to obtain a polyacrylate chelating resin.

[0037] The obtained polyacrylate chelating resin 85 parts, divinylbenzene crosslinking agent 0.4 parts, straw biochar 1.0 parts, and deionized water 120 parts are added to a reactor and stirred uniformly for 20 min to obtain a biochar modified polyacrylate chelating resin.

[0038] (4) Preparation of a material for improving the conductivity of substation soil.

[0039] Mix vermiculite 25 parts, hydroxyapatite 3 parts, bentonite 12 parts, quicklime 30 parts, biochar modified polyacrylate chelating resin 17 parts, and corn straw 35 parts, and stir uniformly to obtain the material.

[0040] Example 2

[0041] The present embodiment provides a preparation method of a material for improving the conductivity of substation soil, the steps are as follows:

[0042] (1) Preparation of hydroxyapatite: the same as in Example 1.

[0043] (2) Preparation of straw biochar.

[0044] The corn straw core is not separated and crushed, 3 mol / L zinc chloride solution is added, soaked at room temperature for 24 h, and then dried at 80℃. After drying, it is put into a crucible and activated at 500℃ for 90 min. The product is washed with 10% dilute hydrochloric acid solution, washed with water, adjusted to pH = 7, dried, ground and sieved to a particle size of 80% passing through a 200 mesh sieve to obtain straw biochar.

[0045] (3) Preparation of biochar modified polyacrylate chelating resin.

[0046] The span-20, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate are mixed in a mass ratio of 2.3:1:0.9 to prepare a composite emulsifier. The composite emulsifier is dissolved in deionized water and then mixed with ethyl acrylate and butyl acrylate monomers in a molar ratio of 2:1. The mixture is heated to 90℃ and stirred, and 0.5% ammonium persulfate is added as a reaction initiator. The mass ratio of the mixed monomers, composite emulsifier and initiator is 100:2:0.63. After the polymerization is completed, the mixture is cooled to room temperature for 60 min, adjusted to pH = 7, and a polyacrylate copolymer is obtained.

[0047] The polyacrylate copolymer is mixed with triethylenetetramine in a mass ratio of 4:1, heated to 85℃ and maintained for 2.5 h, then soaked and stirred with 2 mol / L hydrochloric acid solution, adjusted to neutral pH, and washed with deionized water and acetone to obtain a polyacrylate chelating resin.

[0048] The polyacrylate chelating resin is mixed with diethylenephenyl crosslinking agent 0.4 parts, straw biochar 1.1 parts, and deionized water 120 parts in a reactor and stirred uniformly for 20 min to obtain a biochar modified polyacrylate chelating resin.

[0049] (4) Preparation of a material for improving the conductivity of substation soil.

[0050] Mix vermiculite 30 parts, hydroxyapatite 3.5 parts, bentonite 13 parts, quicklime 32 parts, biochar modified polyacrylate chelating resin 18 parts, and corn straw 35 parts, and stir uniformly to obtain the material.

[0051] Example 3

[0052] The present embodiment provides a preparation method of a material for improving the conductivity of substation soil, the steps are as follows:

[0053] (1) Preparation of hydroxyapatite: same as example 1.

[0054] (2) Preparation of straw biochar.

[0055] The corn straw core is not separated and crushed, 3 mol / L zinc chloride solution is added, soaked at room temperature for 24 h, and then dried at 80℃. After drying, it is put into a crucible and activated at 550℃ for 80 min. The product is washed with 10% dilute hydrochloric acid solution, washed with water, adjusted to pH = 7, dried, ground and sieved to a particle size of 80% passing through a 200 mesh sieve to obtain straw biochar.

[0056] (3) Preparation of biochar modified polyacrylate chelating resin.

[0057] A composite emulsifier is prepared by mixing span-20, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate in a mass ratio of 2.3:1:0.9. The composite emulsifier is dissolved in deionized water and then mixed with ethyl acrylate and butyl acrylate monomers in a molar ratio of 1:2. The mixture is heated to 95℃ and polymerized by adding ammonium persulfate as a reaction initiator in a mass ratio of 0.5%. The mass ratio of the mixed monomers, composite emulsifier and initiator is 100:3:0.7. After cooling to room temperature for 60 min, the pH is adjusted to 7 to obtain a polyacrylate copolymer.

[0058] The obtained polyacrylate copolymer is mixed with triethylenetetramine in a mass ratio of 2:1, heated to 80℃ and maintained for 3 h. Then it is fully soaked and stirred with 2 mol / L hydrochloric acid solution, adjusted to neutral pH, and washed with deionized water and acetone to obtain a polyacrylate chelating resin.

[0059] The obtained polyacrylate chelating resin (80 parts), divinylbenzene crosslinking agent (0.3 parts), straw biochar (0.8 parts) and deionized water (120 parts) are added to a reactor and stirred uniformly for 20 min to obtain a biochar modified polyacrylate chelating resin.

[0060] (4) Preparation of a material for improving the conductivity of substation soil.

[0061] Mix vermiculite (20 parts), hydroxyapatite (2 parts), bentonite (10 parts), quicklime (25 parts), biochar modified polyacrylate chelating resin (15 parts) and corn straw (40 parts) and stir uniformly to obtain the material.

[0062] Example 4

[0063] The present embodiment provides a preparation method of a material for improving the conductivity of substation soil, the steps are as follows:

[0064] (1) Preparation of hydroxyapatite: same as example 1.

[0065] (2) Preparation of straw biochar.

[0066] The corn straw core is not separated and crushed, 3 mol / L zinc chloride solution is added, soaked at room temperature for 24 h, and then dried at 80℃. After drying, it is put into a crucible and activated at 600℃ for 90 min. The product is washed with 10% dilute hydrochloric acid solution, washed with water, adjusted to pH = 7, dried, ground and sieved to a particle size of 80% passing through a 200 mesh sieve to obtain straw biochar.

[0067] (3) Preparation of biochar modified polyacrylate chelating resin.

[0068] A composite emulsifier is prepared by mixing span-20, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate in a mass ratio of 2.3:1:0.9. The composite emulsifier is dissolved in deionized water, and then 2:1 molar ratio of ethyl acrylate and butyl acrylate mixed monomers are added. The mixture is heated and stirred to 80℃, and 0.5% ammonium persulfate is added as a reaction initiator. The mass ratio of mixed monomers, composite emulsifier and initiator is 100:2:0.63. After the polymerization is completed, the mixture is cooled to room temperature for 60 min, and the pH is adjusted to 7 to obtain a polyacrylate copolymer.

[0069] The obtained polyacrylate copolymer is mixed with triethylenetetramine in a mass ratio of 2:1, heated to 80℃ and maintained for 3h. Then it is fully soaked and stirred with 2 mol / L hydrochloric acid solution, the pH is adjusted to neutral, and then washed with deionized water and extracted with acetone to obtain a polyacrylate chelating resin.

[0070] The obtained polyacrylate chelating resin 90 parts, divinylbenzene crosslinking agent 0.5 parts, straw biochar 1.2 parts, and deionized water 120 parts are added to a reactor and stirred uniformly for 20 min to obtain a biochar modified polyacrylate chelating resin.

[0071] (4) Preparation of a material for improving the soil conductivity of a transformer station.

[0072] Mix vermiculite 35 parts, hydroxyapatite 4 parts, bentonite 15 parts, quicklime 35 parts, biochar modified polyacrylate chelating resin 20 parts, and corn straw 30 parts, and stir uniformly to obtain the product.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is in step (3), which is as follows:

[0075] Sodium oleate, sodium abietate, sodium laurate were dissolved in deionized water to form a complex emulsifier with a mass ratio of 7:3.5:1, then ethyl acrylate and butyl acrylate mixed monomers with a molar concentration ratio of 2:1 were added, and the mixture was stirred and heated to 80℃, then 0.5% ammonium persulfate was added as a reaction initiator, wherein the mass ratio of mixed monomers, complex emulsifier and initiator was 100:1.8:0.9, and the mixture was shaken well to obtain a pre-emulsion; the obtained product was mixed with triethylenetetramine in a mass ratio of 4:1, and the reaction was maintained for 1.5h, then the product was fully soaked and stirred with 2mol / L hydrochloric acid solution, the pH was adjusted to neutral, then deionized water was washed, and acetone was extracted; the output, deionized water, divinylbenzene and straw biochar were added to the reactor and stirred uniformly for 20min to obtain a biochar modified polyethyl acrylate chelating resin.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is in step (3), which is specifically:

[0078] Span-20, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate were dissolved in deionized water to form a complex emulsifier with a mass ratio of 2.3:1:0.9, then methyl methacrylate monomer was added, the mixture was stirred and heated to 80℃, then 1% sodium bisulfite was added in batches for polymerization, wherein the mass ratio of mixed monomers, complex emulsifier and 1% sodium bisulfite was 100:2:0.9, after the polymerization was completed, the mixture was cooled to room temperature for 60min, and the pH was adjusted; the obtained product was mixed with triethylenetetramine in a mass ratio of 4:1, and the reaction was maintained for 1.5h, then the product was fully soaked and stirred with 2mol / L hydrochloric acid solution, the pH was adjusted to neutral, then deionized water was washed, and acetone was extracted; the output, deionized water, divinylbenzene and straw biochar were added to the reactor and stirred uniformly for 20min to obtain a biochar modified polymethyl methacrylate chelating resin.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 1 is in step (3), which is specifically:

[0081] The composite emulsifier composed of span-20, octyl phenol polyoxyethylene-10 and sodium dodecyl sulfate in a mass ratio of 2.3:1:0.9 is dissolved in deionized water, then added to the ethyl methacrylate monomer mixture, stirred and heated to 80℃, and 0.5% ammonium persulfate is added as an initiator for polymerization reaction, wherein the mass ratio of the monomer mixture, composite emulsifier and initiator is 100:1.4:0.7, after the polymerization is completed, it is cooled to room temperature for 60 minutes, and the pH is adjusted; the obtained product is mixed with triethylenetetramine in a mass ratio of 4:1, the temperature is raised and the reaction is maintained for 1.5 hours, then it is fully soaked and stirred with 2 mol / L hydrochloric acid solution, the pH is adjusted to neutral, then it is washed with deionized water and extracted with acetone; the output, deionized water, divinylbenzene and straw biochar are added to the reactor and stirred uniformly for 20 minutes to obtain the biochar modified polymethyl methacrylate chelating resin.

[0082] Comparative Example 4

[0083] (1) The hydroxyapatite was prepared in the same manner as in Example 1.

[0084] (2) The polyacrylate chelating resin was prepared.

[0085] The polyacrylate copolymer and the polyacrylate chelating resin were prepared in the same manner as in Example 1.

[0086] (3) The material for improving the soil conductivity of the transformer station was prepared.

[0087] The vermiculite 25 parts, hydroxyapatite 3 parts, bentonite 12 parts and quicklime 30 parts were mixed and stirred uniformly to obtain the product.

[0088] Application Example

[0089] The materials prepared in Examples 1-4 and Comparative Examples 1-4 were added to the constant temperature incubator containing the transformer station soil sample at a dosage of 10 g / kg, and the incubation time was 30 days; the heavy metal determination was carried out by BCR method, and the soil moisture content was determined by neutron instrument method. The changes of the physicochemical properties of the original soil sample and the soil sample treated in different experimental groups are shown in Table 1.

[0090] Table 1 Changes of soil physicochemical properties in different experimental groups

[0091]

[0092]

[0093] It can be seen from Table 1 that the material for improving the soil conductivity of a transformer station prepared by the application can effectively reduce the content of heavy metals in the soil, and reduce the moisture content of the soil, thereby improving the resistivity of the soil to achieve the function of slowing down the discharge and protecting the equipment of the transformer station. In the composite emulsifier, the emulsion particle size decreases with the increase of the amount of emulsifier, but within a certain range of emulsifier, the particle size cannot be infinitely reduced. Considering that too much emulsifier has an adverse effect on the performance of the film, the appropriate amount of emulsifier and the mass ratio of mixed monomers should be 1.5:100, at which the emulsion has a smaller particle size and a narrower particle size distribution. With the increase of the amount of initiator, the conversion rate of monomer increases continuously, but when the amount of initiator increases to near saturation, the conversion rate of monomer increases slowly. The initiator sodium persulfate will leave more SO4 2- after the completion of the polymerization reaction, and free SO4 2- will have a negative impact on the performance of the coating film. Therefore, considering comprehensively, the mass ratio of initiator to mixed monomers is about 0.8:100, which is more appropriate. The biochar modified polyacrylate chelating resin has good stability, water resistance, weather resistance and mechanical properties, good film forming property, strong adhesion to fabric, low price and simple preparation process. The biochar modified material improves the defects of the traditional chelating resin, such as poor hydrophilicity, poor resistance to organic pollution and low secondary recycling rate. Among the above modifiers, the passivation effect of example 1 on soil heavy metals and the improvement of soil resistivity are particularly significant, which proves the effectiveness of the material formula used in the application.

[0094] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, without departing from the technical principles of the application, a number of improvements and modifications can be made, which should also be considered as the protection scope of the application.

Claims

1. A material for improving the electrical conductivity of substation soil, characterized in that, The raw materials include the following parts by weight: vermiculite 20-35 parts, hydroxyapatite 2-4 parts, bentonite 10-15 parts, quicklime 25-35 parts, biochar modified polyacrylate chelating resin 15-20 parts, and corn stalks 30-40 parts. The preparation method of the biochar-modified polyacrylate chelating resin includes the following steps: The straw husk and core are not separated and crushed, soaked in an activator, and then dried, activated, washed with detergent, washed with water, pH adjusted, dried, ground and screened to obtain straw biochar. The polyacrylate copolymer was added to triethylenetetramine, the temperature was raised to maintain the reaction, and then the mixture was soaked and stirred in hydrochloric acid solution to adjust the pH to neutral. The mixture was then washed with deionized water and extracted with acetone to obtain polyacrylate chelating resin. Polyacrylate chelating resin, crosslinking agent, straw biochar and deionized water are mixed and stirred evenly to obtain biochar modified polyacrylate chelating resin.

2. The material for improving the conductivity of substation soil according to claim 1, characterized in that, The biochar-modified polyacrylate chelating resin comprises the following raw materials in parts by weight: 80-90 parts polyacrylate chelating resin, 0.3-0.5 parts divinylbenzene crosslinking agent, 0.8-1.2 parts straw biochar, and 120 parts deionized water.

3. A method for preparing a material for improving the conductivity of substation soil as described in claim 1 or 2, characterized in that, Includes the following steps: The straw husk and core are not separated and crushed, soaked in an activator, and then dried, activated, washed with detergent, washed with water, pH adjusted, dried, ground and screened to obtain straw biochar. The polyacrylate copolymer was added to triethylenetetramine, the temperature was raised to maintain the reaction, and then the mixture was soaked and stirred in hydrochloric acid solution to adjust the pH to neutral. The mixture was then washed with deionized water and extracted with acetone to obtain polyacrylate chelating resin. Polyacrylate chelating resin, crosslinking agent, straw biochar and deionized water are mixed and stirred evenly to obtain biochar modified polyacrylate chelating resin. Biochar-modified polyacrylate chelating resin, vermiculite, hydroxyapatite, bentonite, quicklime, and corn stalks were mixed and stirred evenly to obtain a material for improving the conductivity of substation soil.

4. The method for preparing the material for improving the conductivity of substation soil according to claim 3, characterized in that, The activator is a zinc chloride solution, the activation temperature is 500-600℃, and the activation time is 70-90 min.

5. The method for preparing the material for improving the conductivity of substation soil according to claim 3, characterized in that, The detergent is a 10% hydrochloric acid solution by mass; the particle size of the ground product is 80% passing through a 200-mesh sieve.

6. The method for preparing the material for improving the conductivity of substation soil according to claim 3, characterized in that, The preparation method of the polyacrylate copolymer includes: dissolving the emulsifier in deionized water, adding the mixed monomers, stirring and heating, adding the initiator in batches to complete the polymerization reaction, cooling to room temperature, and adjusting the pH to neutral to obtain the copolymer.

7. The method for preparing the material for improving the conductivity of substation soil according to claim 6, characterized in that, The emulsifier is a composite emulsifier system composed of sorbitan monolaurate, octylphenol polyoxyethylene-10 and sodium dodecyl sulfate in a mass ratio of 2.3:1:0.

9. The mixed monomers include ethyl acrylate and butyl acrylate in a molar ratio of (0.5-2):

1. The initiator is ammonium persulfate. The mass ratio of the mixed monomers, emulsifier and initiator is 100:(1.5-3):(0.6-0.7).

8. The method for preparing the material for improving the conductivity of substation soil according to claim 6, characterized in that, The polymerization reaction is carried out at a temperature of 80-95℃.

9. The method for preparing the material for improving the conductivity of substation soil according to claim 3, characterized in that, The polyacrylate copolymer and triethylenetetramine are mixed at a mass ratio of (2-4):1, heated to 65-85℃ and maintained for 2.5-3 hours, and then thoroughly soaked and stirred with 2 mol / L hydrochloric acid solution.

10. The method for preparing the material for improving the conductivity of substation soil according to claim 3, characterized in that, The method for preparing the hydroxyapatite includes: Weigh calcium nitrate tetrahydrate and diammonium hydrogen phosphate according to the ratio of hydroxyapatite n(Ca):n(P)=5:3=1.67, and prepare calcium nitrate solution and diammonium hydrogen phosphate solution respectively. Diammonium hydrogen phosphate solution was added to calcium nitrate tetrahydrate and stirred at a constant temperature. Ammonia was added to adjust the pH value to between 10 and 10.

5. After aging and washing, a solid product was obtained. The solid product was dried, ground and sintered to obtain hydroxyapatite powder.

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