CN110903829A - Heavy metal agricultural soil remediation method - Google Patents

Heavy metal agricultural soil remediation method Download PDF

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Publication number
CN110903829A
CN110903829A CN201911207690.7A CN201911207690A CN110903829A CN 110903829 A CN110903829 A CN 110903829A CN 201911207690 A CN201911207690 A CN 201911207690A CN 110903829 A CN110903829 A CN 110903829A
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soil
solid
soil remediation
curing agent
crown ether
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陈宽
陈勇
黄雪敏
陈雷
陈再红
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Ningbo Fengkeyuan Agricultural Technology Co Ltd
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Ningbo Fengkeyuan Agricultural Technology Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K17/00Soil-conditioning materials or soil-stabilising materials
    • C09K17/40Soil-conditioning materials or soil-stabilising materials containing mixtures of inorganic and organic compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/12Naturally occurring clays or bleaching earth
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/24Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00Aspects relating to sorbent materials
    • B01J2220/40Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48Sorbents characterised by the starting material used for their preparation
    • B01J2220/4812Sorbents characterised by the starting material used for their preparation the starting material being of organic character
    • B01J2220/4868Cells, spores, bacteria

Abstract

The invention relates to the field of soil remediation, in particular to a heavy metal agricultural soil remediation method. The invention discloses a heavy metal agricultural soil remediation method, which is characterized by comprising the following steps: (1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 35-50 parts of biochar; 8-20 parts of bentonite; 5-10 parts of a curing agent; (2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1: 10-20 to obtain the polluted soil containing the soil remediation agent; (3) and spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing for 5-7 days at room temperature to obtain the improved soil. The invention adopts a method of combining two curing agents for repairing different heavy metals in soil, and the two curing agents supplement each other and act together, thereby having excellent effect on repairing soil.

Description

Heavy metal agricultural soil remediation method
Technical Field
The invention relates to the field of soil remediation, in particular to a heavy metal agricultural soil remediation method.
Background
Heavy metal pollution of soil has the characteristics of concealment, long-term property and irreversibility, the residence time of pollutants in the soil is long, plants or microorganisms cannot degrade, the heavy metal pollution not only causes the degradation of the soil and the reduction of the yield and the quality of crops, but also endangers the life and the health of human beings through direct contact and food chain.
Soil pollution not only causes serious harm to the ecological environment and human health, but also hinders the development of economy in China. The soil pollution type is mainly heavy metal, and mainly comprises chromium, cadmium, mercury, arsenic, lead, copper, zinc, nickel and the like. The heavy metal soil pollution has wide distribution range, large pollution amount, high treatment cost and long treatment period. Among them, the most widely used heavy metal soil remediation method at present is the chemical immobilization method. The chemical fixation restoration is that chemical reagents or chemical materials are added into the polluted environment, the polluted environment conditions are adjusted by utilizing the chemical reagents or the chemical materials, the form, the water solubility and the mobility of pollutants are changed by controlling the chemical reaction conditions, the pollutants are passivated to form insoluble or poorly mobile substances with low toxicity, so that the biological effectiveness of the pollutants in the polluted environment is reduced, and the migration of the pollutants to other environmental systems is reduced. Meanwhile, the pollution can be eliminated more durably by combining other restoration technical means, and the chemical restoration of the polluted environment is realized. However, the existing chemical immobilization method is more researched for treating soil polluted by single heavy metal, but the research on the condition that multiple heavy metals exist simultaneously is lacked.
Disclosure of Invention
Aiming at the problems, the invention provides a heavy metal agricultural soil remediation method, which comprises the following steps:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 35-50 parts of biochar; 8-20 parts of bentonite; 5-10 parts of a curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1: 10-20 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing for 5-7 days at room temperature to obtain improved soil;
wherein the curing agent comprises a first curing agent and a second curing agent; the first curing agent is obtained by modifying starch through a crown ether complex; the second curing agent is obtained by immobilizing nitrosomonas on a porous carrier.
Preferably, the crown ether complex is obtained by complexing 15-crown-5 with amantadine.
Preferably, the porous support is obtained by reacting zirconium oxychloride with terephthalic acid.
Preferably, the biochar is prepared by taking straws and/or manure as raw materials, carrying out vacuum pyrolysis for 1-2 h at 200-300 ℃, and then grinding the materials to particles with the particle size of 2-3 mm.
Preferably, the first curing agent has a good fixing effect on heavy metals Pb, Cd, Hg and As.
Preferably, the second curing agent has a good effect of fixing heavy metals of Cr, Ni, Cu and Zn.
Preferably, the proportion of the first curing agent and the second curing agent can be adjusted according to the content of heavy metals in soil.
Preferably, the thickness of the soil applied by the soil remediation agent is 20cm +/-1 cm.
Preferably, the preparation method of the first curing agent is as follows:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown ether-5 to the amantadine is 2-3: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 2-5; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 5-8;
step 2, uniformly mixing starch and water, heating and stirring for 20-50 min at the temperature of 60-80 ℃, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the starch to the water is 1: 10-15;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiation until the liquid boils, stopping radiation for 1min, repeating the process of radiation until the liquid boils and stopping radiation for 1min until the mixed solution A is in an immobile state, and obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 15-20; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
Preferably, the starch is one or more of tapioca starch, sweet potato starch and corn starch.
Preferably, the preparation method of the second curing agent is as follows:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, centrifuging for 7-10 days, and taking solid particles to obtain cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; wherein the mass ratio of the components in the culture medium is as follows: ammonium sulfate: potassium dihydrogen phosphate: magnesium sulfate heptahydrate: calcium chloride dihydrate: 1000 parts of copper sulfate pentahydrate: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 20-30; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 0.5-1; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 5-8; the solid-to-liquid ratio of the zirconium oxychloride to the deionized water is 1: 0.5-1; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 10-20 min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 20-40 parts of; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1:10 to 20.
The invention has the beneficial effects that:
1. the method combines a chemical method and a biological method to repair the soil, plays a synergistic role in repairing the soil pollution, greatly reduces the content of heavy metals in the soil, improves the structure of the soil, can decompose sediments and organic matters in the soil, and finally achieves the effect of repairing the soil. According to the method, the soil polluted by the heavy metal is repaired in a mode of mixing the biochar, the bentonite and the curing agent to form the repairing agent, components in the repairing agent play a complementary role in adsorbing the heavy metal, water is sprayed until the humidity of the soil reaches 30-50% in the repairing process, the contact between the heavy metal in the soil and the repairing agent is facilitated, and the time spent on soil repairing can be greatly shortened. The invention adopts a method of combining two curing agents for repairing different heavy metals in soil, and the two curing agents supplement each other and act together, thereby having excellent effect on repairing soil.
2. The first curing agent used in the invention is prepared by reacting crown ether complex with starch, so that the obtained product has the capability of adsorbing heavy metals, and detection shows that the first curing agent has stronger adsorbability on heavy metals Pb, Cd, Hg and As. Crown ether has certain toxicity and instability, and amantadine and crown ether can form a coordination modifier, so that the toxicity of crown ether is weakened, and the stability of crown ether is improved.
15-crown-5 has adsorbability for certain specific metals (such as sodium and lithium), but has lower adsorbability for heavy metals and less adsorbability, and after the starch is modified by reaction with starch, the modified starch not only has enhanced selectivity for the heavy metals, but also has increased adsorbability. The adsorption principle of the modified starch on heavy metal ions is as follows: the crown ether contains a plurality of oxygen-methylene groups in the molecule, oxygen atoms on the groups form hydrogen bonds with hydroxyl on the surface of the starch during modification and then are combined with the starch, and when heavy metals appear, heavy metal ions firstly form coordinate bonds with the starch hydroxyl and then react with oxygen on the starch hydroxyl and oxygen atoms on the crown ether complex to form a more stable complex. The surface of the modified starch becomes extremely rough, and a large number of irregularly arranged pores are formed, so that the specific surface area of the starch is increased, and favorable conditions are provided for adsorbing a large number of heavy metal ions.
In the preparation process of the first curing agent, starch is gelatinized first, so that hydrogen bond connection between starch molecules is broken, and further, the reaction between a colloid state and a subsequent crown ether complex can be more rapid and complete. Then, after the crown ether complex is added, the reaction condition is microwave radiation, and the microwave is periodically switched on and off during the microwave radiation, so that the reaction of the high molecular compound is maintained, and the phenomenon that the reaction is not complete due to the fact that the solvent is evaporated too fast can be prevented. After the reaction is finished, the produced product is in a gel state, and the cooling time is set to further combine the crown ether complex and the starch more tightly.
3. The second curing agent prepared by the invention is immobilized on a zirconium salt material by using nitrosomonas bacterium, wherein the loading is different from the conventional bacterial loading, the nitrosomonas bacterium is added in the preparation process of the carrier and is loaded on the carrier under the action of microwave radiation, and the advantages that the finally obtained product has stronger integrity and integrality, the nitrosomonas bacterium exists on the carrier more stably, and the heavy metal adsorption and fixation are more stable finally.
The detection shows that the second curing agent has stronger reduction and adsorption capacity to heavy metals of Cr, Ni, Cu and Zn, and can quickly reduce hexavalent Cr into trivalent Cr particularly aiming at the hexavalent Cr with higher toxicity. Amino and hydroxyl on the surface of nitrosomonas can be tightly crosslinked with heavy metal, the modified zirconium salt carrier has mesoporous property, the aperture is 10-50 nm, and the mesoporous structure is not only combined with amino, carboxyl, hydroxyl and other functional groups on the surface of nitrosomonas, but also beneficial to adsorption and fixation of heavy metal. After the heavy metal is fixed, the fixed metal can be removed by using sodium hydroxide solution for elution, and the eluted second curing agent still has high-efficiency heavy metal adsorption and strong reusability.
Detailed Description
The invention is further described with reference to the following examples.
Example 1
A heavy metal agricultural soil remediation method, comprising:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 45 parts of biochar; 10 parts of bentonite; 8 parts of a curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1:15 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing at room temperature for 6 days to obtain improved soil;
wherein the curing agent comprises a first curing agent and a second curing agent; the biochar is prepared by taking straws and/or manure as raw materials, carrying out vacuum pyrolysis for 1-2 h at 200-300 ℃, and then grinding the materials to particles with the particle size of 2-3 mm.
The preparation method of the first curing agent is as follows:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown-5 to the amantadine is 2.5: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 3; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 7;
step 2, uniformly mixing the cassava starch with water, heating and stirring at the temperature of 60-80 ℃ for 20-50 min, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the cassava starch to the water is 1: 12;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiation until the liquid boils, stopping radiation for 1min, repeating the process of radiation until the liquid boils and stopping radiation for 1min until the mixed solution A is in an immobile state, and obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 16; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
The preparation method of the second curing agent comprises the following steps:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, centrifuging after culturing for 8d, and taking solid particles to obtain cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; wherein the mass ratio of the components in the culture medium is as follows: ammonium sulfate: potassium dihydrogen phosphate: magnesium sulfate heptahydrate: calcium chloride dihydrate: 1000 parts of copper sulfate pentahydrate: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 25; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 0.75; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 6; the solid-to-liquid ratio of zirconium oxychloride to deionized water is 1: 0.75; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 15min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 30, of a nitrogen-containing gas; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1: 15.
in the above, the first curing agent is used for fixing heavy metals of Pb, Cd, Hg and As; the second curing agent is used for fixing heavy metals of Cr, Ni, Cu and Zn.
Example 2
A heavy metal agricultural soil remediation method, comprising:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 35 parts of biochar; 8 parts of bentonite; 5 parts of a curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1:10 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing for 5 days at room temperature to obtain improved soil;
wherein the curing agent comprises a first curing agent and a second curing agent; the biochar is prepared by taking straws and/or manure as raw materials, carrying out vacuum pyrolysis for 1-2 h at 200-300 ℃, and then grinding the materials to particles with the particle size of 2-3 mm.
The preparation method of the first curing agent is as follows:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown ether-5 to the amantadine is 2: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 2; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 5;
step 2, uniformly mixing the cassava starch with water, heating and stirring at the temperature of 60-80 ℃ for 20-50 min, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the cassava starch to the water is 1: 10;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiation until the liquid boils, stopping radiation for 1min, repeating the process of radiation until the liquid boils and stopping radiation for 1min until the mixed solution A is in an immobile state, and obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 15; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
The preparation method of the second curing agent comprises the following steps:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, and centrifuging to obtain solid particles after culturing for 7d, thereby obtaining the cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; the mass ratio of the deionized water to the ammonium sulfate, the potassium dihydrogen phosphate, the magnesium sulfate heptahydrate, the calcium chloride dihydrate and the copper sulfate pentahydrate is 1000: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 20; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 0.5; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 5; the solid-to-liquid ratio of the zirconium oxychloride to the deionized water is 1: 0.5; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 10min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 20; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1: 10.
in the above, the first curing agent is used for fixing heavy metals of Pb, Cd, Hg and As; the second curing agent is used for fixing heavy metals of Cr, Ni, Cu and Zn.
Example 3
A heavy metal agricultural soil remediation method, comprising:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 50 parts of biochar; 20 parts of bentonite; 10 parts of a curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1:20 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing for 7 days at room temperature to obtain improved soil;
wherein the curing agent comprises a first curing agent and a second curing agent; the biochar is prepared by taking straws and/or manure as raw materials, carrying out vacuum pyrolysis for 1-2 h at 200-300 ℃, and then grinding the materials to particles with the particle size of 2-3 mm.
The preparation method of the first curing agent is as follows:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown ether-5 to the amantadine is 3: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 5; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 8;
step 2, uniformly mixing the cassava starch with water, heating and stirring at the temperature of 60-80 ℃ for 20-50 min, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the cassava starch to the water is 1: 15;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiation until the liquid boils, stopping radiation for 1min, repeating the process of radiation until the liquid boils and stopping radiation for 1min until the mixed solution A is in an immobile state, and obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 20; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
The preparation method of the second curing agent comprises the following steps:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, centrifuging after culturing for 10 days, and taking solid particles to obtain cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; the mass ratio of the deionized water to the ammonium sulfate, the potassium dihydrogen phosphate, the magnesium sulfate heptahydrate, the calcium chloride dihydrate and the copper sulfate pentahydrate is 1000: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 30, of a nitrogen-containing gas; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 1; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 8; the solid-to-liquid ratio of zirconium oxychloride to deionized water is 1: 1; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 20min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 40; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1: 20.
in the above, the first curing agent is used for fixing heavy metals of Pb, Cd, Hg and As; the second curing agent is used for fixing heavy metals of Cr, Ni, Cu and Zn.
Comparative example 1
A heavy metal agricultural soil remediation method, comprising:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 45 parts of biochar; 10 parts of bentonite; 8 parts of a first curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1:15 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing at room temperature for 6 days to obtain improved soil;
the biochar is prepared by taking straws and/or manure as raw materials, performing vacuum pyrolysis at 200-300 ℃ for 1-2 hours, and grinding the materials to particles with the particle size of 2-3 mm.
The preparation method of the first curing agent is as follows:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown-5 to the amantadine is 2.5: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 3; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 7;
step 2, uniformly mixing the cassava starch with water, heating and stirring at the temperature of 60-80 ℃ for 20-50 min, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the cassava starch to the water is 1: 12;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiation until the liquid boils, stopping radiation for 1min, repeating the process of radiation until the liquid boils and stopping radiation for 1min until the mixed solution A is in an immobile state, and obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 16; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
Comparative example 2
A heavy metal agricultural soil remediation method, comprising:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 45 parts of biochar; 10 parts of bentonite; 8 parts of a second curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1:15 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing at room temperature for 6 days to obtain improved soil;
the biochar is prepared by taking straws and/or manure as raw materials, performing vacuum pyrolysis at 200-300 ℃ for 1-2 hours, and grinding the materials to particles with the particle size of 2-3 mm.
The preparation method of the second curing agent comprises the following steps:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, centrifuging after culturing for 8d, and taking solid particles to obtain cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; the mass ratio of the deionized water to the ammonium sulfate, the potassium dihydrogen phosphate, the magnesium sulfate heptahydrate, the calcium chloride dihydrate and the copper sulfate pentahydrate is 1000: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 25; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 0.75; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 6; the solid-to-liquid ratio of zirconium oxychloride to deionized water is 1: 0.75; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 15min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 30, of a nitrogen-containing gas; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1: 15.
in order to prove the present invention more clearly, inventive example 1, example 2, example 3, comparative example 1 and comparative example 2 were applied and the effects were examined.
Selecting a land with a Ningbo place polluted by a plurality of heavy metals, and applying the methods of example 1, example 2, example 3, comparative example 1 and comparative example 2 to the soil polluted by the heavy metals; the content of heavy metals before and after soil remediation is detected by taking national standard GB15618-2008 as a standard, and the result is shown in Table 1;
wherein, the detection after ① soil restoration needs to sieve out the curing agent and then carry out detection;
② the thickness of the applied soil is 20cm +/-1 cm;
③ the weight ratio of the first curing agent to the second curing agent in example 1, example 2 and example 3 was 1: 1.
TABLE 1 heavy metal content determination
As can be seen from the above table 1, after the heavy metal contaminated soil is treated in the examples 1, 2 and 3 of the present invention, Pb, Cd, Hg, As, Cr, Ni, Cu and Zn in the contaminated soil can meet the national standard; the data of comparative example 1 show that the first curing agent has better adsorption performance on heavy metals Pb, Cd, Hg and As; the data of comparative example 2 show that the second curing agent has better adsorption performance on heavy metals of Cr, Ni, Cu and Zn.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (8)

1. A heavy metal agricultural soil remediation method is characterized by comprising the following steps:
(1) preparing a soil remediation agent, wherein the soil remediation agent comprises the following components in parts by weight: 35-50 parts of biochar; 8-20 parts of bentonite; 5-10 parts of a curing agent;
(2) uniformly stirring the soil remediation agent and the soil polluted by heavy metals according to the weight ratio of 1: 10-20 to obtain the polluted soil containing the soil remediation agent;
(3) spraying water mist to the contaminated soil containing the soil remediation agent to enable the water content to reach 30% -50%, and standing for 5-7 days at room temperature to obtain improved soil;
wherein the curing agent comprises a first curing agent and a second curing agent; the first curing agent is obtained by modifying starch through a crown ether complex; the second curing agent is obtained by immobilizing nitrosomonas on a porous carrier.
2. The heavy metal agricultural soil remediation method of claim 1, wherein the crown ether complex is obtained by complexing 15-crown-5 with amantadine.
3. The heavy metal agricultural soil remediation method of claim 1, wherein the porous support is formed by reacting zirconium oxychloride with terephthalic acid.
4. The method for remediating heavy metal agricultural soil as recited in claim 1, wherein the biochar is prepared by taking straws and/or manure as raw materials, performing vacuum pyrolysis at 200-300 ℃ for 1-2 hours, and grinding the raw materials into particles with a particle size of 2-3 mm.
5. The heavy metal agricultural soil remediation method of claim 1, wherein the first curing agent is prepared by the following method:
step 1, mixing 15-crown ether-5 with amantadine, adding 5mol/L hydrochloric acid solution, heating to 50-60 ℃, stirring for reaction for 2-4 hours, cooling to room temperature, adding 1mol/L sodium hydroxide solution, stirring for 1-2 hours, filtering, and drying at 60 ℃ to obtain a crown ether complex;
wherein the mass ratio of the 15-crown ether-5 to the amantadine is 2-3: 1; the volume ratio of the 15-crown ether-5 to the hydrochloric acid solution is 1: 2-5; the volume ratio of the 15-crown ether-5 to the sodium hydroxide solution is 1: 5-8;
step 2, uniformly mixing starch and water, heating and stirring for 20-50 min at the temperature of 60-80 ℃, and then cooling to room temperature to obtain a starch paste;
wherein the solid-to-liquid ratio of the starch to the water is 1: 10-15;
step 3, uniformly mixing the crown ether complex with deionized water, adding the starch paste, and vibrating uniformly to obtain a mixed solution A; placing the mixed solution A under the microwave condition of 500W for radiating until the liquid boils, stopping radiating for 1min, and then repeating the process of radiating until the liquid boils-stopping radiating for 1min until the mixed solution A is in an immobile state, thus obtaining a solid B;
wherein the solid-to-liquid ratio of the crown ether complex to the deionized water is 1: 15-20; the mass ratio of the starch paste to the crown ether complex is 1: 15;
and 4, cooling the solid B at room temperature for 18-20 h, washing with ethyl acetate for 3 times, drying at 60 ℃, and crushing into powder to obtain the first curing agent.
6. The heavy metal agricultural soil remediation method of claim 5, wherein the starch is one or more of tapioca starch, sweet potato starch and corn starch.
7. The heavy metal agricultural soil remediation method of claim 1, wherein the second curing agent is prepared by the following method:
a. adding nitrosomonas into a culture medium, culturing under a dark condition, setting the culture temperature to be 25-28 ℃, centrifuging for 7-10 days, and taking solid particles to obtain cultured nitrosomonas;
the preparation method of the culture medium comprises the following steps: sequentially adding ammonium sulfate, potassium dihydrogen phosphate, magnesium sulfate heptahydrate, calcium chloride dihydrate and copper sulfate pentahydrate into deionized water, stirring and mixing uniformly, and then sterilizing; wherein the mass ratio of the components in the culture medium is as follows: ammonium sulfate: potassium dihydrogen phosphate: magnesium sulfate heptahydrate: calcium chloride dihydrate: 1000 parts of copper sulfate pentahydrate: 4.95: 0.62: 0.27: 0.04: 0.0002;
b. uniformly mixing zirconium oxychloride and dimethylformamide, adding terephthalic acid, uniformly stirring, adding acetic acid and deionized water, and stirring for 20-30 min to obtain a mixed solution C;
wherein the solid-to-liquid ratio of zirconium oxychloride to dimethylformamide is 1: 20-30; the mass ratio of the zirconium oxychloride to the terephthalic acid is 1: 0.5-1; the solid-to-liquid ratio of zirconium oxychloride to acetic acid is 1: 5-8; the solid-to-liquid ratio of the zirconium oxychloride to the deionized water is 1: 0.5-1; the stirring speed is 300-500 rpm;
c. adding the cultured nitrosomonas into the mixed solution C, uniformly stirring, performing microwave radiation for 10-20 min under the condition of 200W, cooling to room temperature, and centrifuging to obtain a solid D; mixing the solid D with N, N-dimethylformamide, uniformly stirring, soaking for 10-15 h, and drying at 60 ℃ to obtain a second curing agent;
wherein the solid-to-liquid ratio of the cultured nitrosomonas to the mixed solution C is 1: 20-40 parts of; the solid-liquid ratio of the solid D to the N, N-dimethylformamide is 1:10 to 20.
8. The method of claim 1, wherein the soil conditioner is applied to soil with a thickness of 20cm ± 1 cm.
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