CN114101310B - Method for passivating lead-cadmium polluted farmland soil based on biochar-attapulgite compounding - Google Patents

Method for passivating lead-cadmium polluted farmland soil based on biochar-attapulgite compounding Download PDF

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CN114101310B
CN114101310B CN202111300421.2A CN202111300421A CN114101310B CN 114101310 B CN114101310 B CN 114101310B CN 202111300421 A CN202111300421 A CN 202111300421A CN 114101310 B CN114101310 B CN 114101310B
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attapulgite
soil
biochar
lead
cadmium
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张胜田
李群
万金忠
杨璐
王祥
赵远超
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Nanjing Institute of Environmental Sciences MEE
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Abstract

The invention provides a method for passivating lead-cadmium polluted farmland soil based on biochar-attapulgite compounding, which comprises the following steps: s1, drying and crushing the waste wood, and soaking the waste wood in FeSO 4 Carrying out reaction, and carrying out carbonization treatment after the reaction is finished to obtain biochar; s2, crushing attapulgite, acidizing, calcining, mixing with charcoal, and finally granulating; obtaining a biochar-attapulgite compound passivator; s3, adjusting the humidity of the lead-cadmium polluted farmland soil, spreading sepiolite powder, and finally adding a biochar-attapulgite compound passivator for plowing, so that the passivation of the lead-cadmium polluted farmland soil can be completed; the invention utilizes the synergy of the biochar and the attapulgiteThe method has the advantages of promoting the activity transformation of heavy metal lead and cadmium elements in the soil, reducing the bioavailability and the mobility of the heavy metal lead and cadmium, and achieving the purpose of passivation and restoration.

Description

Method for passivating lead-cadmium polluted farmland soil based on biochar-attapulgite compounding
Technical Field
The invention relates to the technical field of lead and cadmium polluted farmland soil remediation, in particular to a method for passivating lead and cadmium polluted farmland soil based on biochar-attapulgite compounding.
Background
With the implementation of industrial activities such as mineral exploitation, smelting and the like and agricultural activities such as sewage irrigation, sludge application, inferior fertilizer application and the like, harmful heavy metals such as lead, cadmium and the like continuously enter the agricultural environment, so that the soil fertility of farmland is degraded, the yield and the quality of agricultural products are reduced, and the food chain finally endangers the health of human bodies; the passivation restoration technology is one of the most common restoration technologies for heavy metal contaminated soil at home and abroad at present, and the main technical means is to add a modifying agent into the soil to change the form or valence state of the heavy metal, convert the pollutants into a state or form which is not easy to dissolve, has small migration capacity or toxicity, and realize harmlessness or reduce the risk of harmfulness to an ecosystem.
The biochar is convenient to obtain and strong in adsorption capacity, can improve the soil fertility, has a good agricultural value as a green and economic soil remediation passivator, and is more worthy of attention in soil remediation of lead-cadmium contaminated farmland; the attapulgite with unique micropore and mesoporous structure has strong adsorption performance on heavy metal ions in soil, but the case of passivating the lead-cadmium polluted soil by compounding the biochar and the attapulgite does not appear in the prior art.
Disclosure of Invention
Aiming at the technical problems, the invention provides a method for passivating the soil of a lead-cadmium polluted farmland based on biochar-attapulgite compounding.
The technical scheme of the invention is as follows: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 3-5 hours at the temperature of 80-110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-5 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with 8-13% of FeSO 4 Uniformly mixing the solution according to the volume ratio of 1: 3-7, carrying out ultrasonic treatment for 5-15 h at the ultrasonic frequency of 500-900 kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 0.4-1.1 MPa, the carbonization temperature to be 450-950 ℃, keeping the pressure for 2-5 hours, and obtaining the required biochar after the modified material in the carbonization tank is naturally cooled;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a screen with 100-300 meshes, adding 25-45% by volume of sulfuric acid solution with the mass concentration of 5-9% into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 800-1350 ℃ for calcining for 2-5 h to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1: 2-4, and adjusting the water content of the mixture to 5-11 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 50-60 ℃ for 2-5 h to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to be 20-45%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 30-90 kg/mu, and maintaining for 5-9 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume 5-9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and uniformly spraying the biochar-attapulgite compounded passivator aqueous solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 150-350 kg/mu, turning over, and maintaining for 15-20 days to complete passivation of the lead and cadmium polluted farmland soil.
Further, in the step S1-3, in the carbonization process of the modified material, the modified material is continuously fed into the carbonization tank at a distance of 5-15 m 3 Introducing mixed gas of oxygen and sulfur dioxide in a volume ratio of 1: 2-5 into the gas inlet flow per hour; the mixed gas of oxygen and sulfur dioxide is introduced into the carbonization tank, so that the thermal decomposition of the biomass in the modified material under the mixed atmosphere is facilitated, and the microporous structure of the biochar is further enlarged.
Further, in the step S2-1, after the attapulgite is crushed, adding distilled water with the volume of 3-5 times of that of the attapulgite, performing ultrasonic dispersion for 15-30 min at the frequency of 800-1500 kHz, then performing centrifugal treatment for 20-40 min at the rotating speed of 1500-3000r/min, collecting the precipitate, and performing drying treatment; through carrying out ultrasonic dispersion and centrifugal separation to the attapulgite and handling, can effectively reduce the content of impurity in the attapulgite to improve pore permeability and the adsorption efficiency that the attapulgite contains.
Further, in the step S3-1, after the lead-cadmium polluted farmland is cleaned, organic fertilizer is scattered into the lead-cadmium polluted farmland soil, wherein the organic fertilizer is one of chicken manure, cow manure and sheep manure; by applying the organic fertilizer to the lead-cadmium polluted farmland soil, the effects of adjusting the pH value of the soil and reducing the bioavailability and the mobility of heavy metals in the soil can be achieved, and meanwhile, the cation exchange capacity of the soil can be increased.
Further, in step S3-1, after the surface sundries of the lead and cadmium polluted farmland soil are cleaned, excavating and transferring the lead and cadmium polluted soil according to the lead and cadmium polluted depth of the soil, paving a barrier cloth in the excavated farmland, and finally backfilling the lead and cadmium polluted soil; can effectively avoid the migration of lead and cadmium pollutants in the soil.
Further, in the step S3-2, after the pre-treated soil is ploughed, planting ryegrass on the surface of the pre-treated soil according to the row spacing of 5-15 cm; by planting ryegrass and utilizing the enrichment effect of plants, lead and cadmium heavy metal pollutants in soil are effectively adsorbed.
Further, after the step S3-1 is finished, uniformly spraying microbial bacteria liquid to the surface of the pretreated soil, wherein the spraying amount of the microbial bacteria liquid is 1-4 kg/mu, and the microbial bacteria liquid is prepared by compounding photosynthetic bacteria liquid, bacillus brevis liquid, saccharomycete liquid, bacillus thuringiensis liquid, bacillus subtilis and lactobacillus liquid according to the volume ratio of 1:2:1:3:2: 2; by uniformly spraying the microbial liquid on the surface of the pretreated soil, the remediation efficiency of the cadmium-polluted soil can be improved, and meanwhile, the organic matter and microorganism content in the soil can be improved.
Further, after the step S2-2 is completed, adding a 1, 2-dimethoxyethane surfactant into the biochar-attapulgite compound passivator, controlling the pH of a reaction system to be 5-8, and mechanically stirring for 15-30 min to obtain a modified biochar-attapulgite compound passivator; wherein the adding amount of the 1, 2-dimethoxyethane surfactant is 7-11 wt% of the biochar-attapulgite compound passivator; by adding the surfactant into the charcoal-attapulgite compounded passivator, the adsorption capacity of the passivator on lead and cadmium heavy metal pollutants can be improved.
Further, in the step S3-2, adding an activating solution with the volume of 5-11% into the biochar-attapulgite compound passivator aqueous solution, and uniformly stirring; the activating solution is formed by mixing humic acid, sodium polyacrylate and deionized water according to the volume ratio of 1:3: 6; the activation solution is added, so that the transformation effect on the forms of lead and cadmium heavy metals in the soil can be realized; meanwhile, humic acid can interact with heavy metal ions in soil, so that the heavy metal pollution condition in the soil is improved.
Further, after the step S1-3 is finished, soaking the biochar in a titanium dioxide dispersion liquid with the volume concentration of 15-35%, keeping the temperature of the mixed system at 45-60 ℃, then magnetically stirring at the speed of 150-350 rpm/min for 15-30 min, filtering out the titanium dioxide dispersion liquid after soaking is finished, and then calcining the biochar in a tubular furnace at the temperature of 500-900 ℃ for 25-45 min; obtaining the biological carbon loaded with titanium dioxide; by loading titanium dioxide on the biochar, organic pollutants adsorbed in the biochar except heavy metal ions can be decomposed by utilizing the photocatalytic oxidation of the titanium dioxide, so that the effective action time of the biochar is prolonged.
Compared with the prior art, the invention has the beneficial effects that:
according to the project, biochar prepared by taking agricultural and forestry waste as a raw material is used as a heavy metal passivator, a clay mineral attapulgite is added to form a compound system, so that the purpose of passivating the soil polluted by lead and cadmium in a farmland is achieved, and the biochar takes waste wood as the raw material, so that the advantages of wide source and low cost are achieved, and the environmental safety problem caused by random stacking of waste wood is avoided;
secondly, the biochar-attapulgite compound passivator prepared by the invention has the advantages of large specific surface area and strong surface activity, can remarkably improve the passivating effect on heavy metals of lead and cadmium in soil, and is beneficial to the restoration and improvement of soil texture; the biochar-attapulgite compounded passivator disclosed by the invention is utilized to perform a series of reactions such as exclusive adsorption, surface complexation, ion exchange, coprecipitation and the like with heavy metal lead and cadmium elements in soil, so that the heavy metal lead and cadmium elements in the soil are promoted to be converted from a form with higher activity to a form with lower activity, and thus, the biological effectiveness and the mobility of the heavy metal lead and cadmium are reduced, and the purpose of passivation and repair is achieved;
thirdly, the method has the advantages of simple operation and low repair cost, the attapulgite has stronger adsorption performance on lead and cadmium heavy metal ions in soil, and meanwhile, the biochar endows the surface of the attapulgite with modified functional groups, so that the synergistic and complementary effects are achieved, the adsorption performance on the heavy metal ions is further improved, powerful technical support is provided for passivation and repair of the heavy metal polluted farmland soil, and the method has better popularization and application prospects.
Detailed Description
Example 1: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 3 hours at the temperature of 80 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-4 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with 8% of FeSO 4 Uniformly mixing the solution according to the volume ratio of 1:3, then carrying out ultrasonic treatment for 5h at the ultrasonic frequency of 500kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 0.4MPa, keeping the carbonization temperature to be 450 ℃, keeping the pressure for 2 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 100-mesh screen, adding 25% by volume of a sulfuric acid solution with the mass concentration of 5% into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 800 ℃ to calcine for 2 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:2, and adjusting the water content of the mixture to 5 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-3.0 mm by a disc granulator; finally, drying the granular material at the temperature of 50 ℃ for 2h to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to be 20%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 30 kg/mu, and maintaining for 5 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume 5 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and then uniformly spraying the biochar-attapulgite compounded passivator aqueous solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 150 kg/mu, turning over, and maintaining for 15 days to complete passivation of the lead-cadmium polluted farmland soil.
Example 2: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 4 hours at the temperature of 97 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 3-5 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 11% 4 Uniformly mixing the solution according to the volume ratio of 1:5, then carrying out ultrasonic treatment for 11h at the ultrasonic frequency of 790kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 0.9MPa, controlling the carbonization temperature to be 795 ℃, maintaining the pressure for 4 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar; finally, soaking the biochar in a titanium dioxide dispersion liquid with the volume concentration of 15%, keeping the temperature of a mixed system at 45 ℃, then magnetically stirring for 15min at the speed of 150rpm/min, filtering out the titanium dioxide dispersion liquid after soaking is finished, and then calcining the biochar in a tubular furnace at the temperature of 500 ℃ for 25 min; obtaining the biochar loaded with titanium dioxide; by loading titanium dioxide on the biochar and utilizing the photocatalytic oxidation effect of the titanium dioxide, organic pollutants adsorbed in the biochar except heavy metal ions can be decomposed, so that the effective action time of the biochar is prolonged;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 220-mesh screen, adding 36% by volume of sulfuric acid solution with the mass concentration of 6% into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1150 ℃ for calcining for 4 hours to obtain heat-treated attapulgite powder; wherein, in the carbonization process of the modified material, the modified material is continuously fed into the carbonization tank by 5m 3 Introducing mixed gas of oxygen and sulfur dioxide in a volume ratio of 1:2 into the gas inlet flow per hour; the mixed gas of oxygen and sulfur dioxide is introduced into the carbonization tank, so that the thermal decomposition of the biomass in the modified material under the mixed atmosphere is facilitated, and the microporous structure of the biochar is further enlarged;
s2-2, uniformly stirring and mixing the titanium dioxide loaded biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:3, and adjusting the water content of the mixture to 9 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 3.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 56 ℃ for 4h to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to 35%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 65 kg/mu, and maintaining for 7 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume being 7 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and uniformly spraying the biochar-attapulgite compounded passivator aqueous solution onto the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 220 kg/mu, turning over, and maintaining for 18 days to complete passivation of the lead and cadmium polluted farmland soil.
Example 3: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing the surface decay layer of the waste wood, then drying for 5 hours at 110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-3 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 13% 4 Uniformly mixing the solution according to the volume ratio of 1:7, then carrying out ultrasonic treatment for 15h at the ultrasonic frequency of 900kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 1.1MPa, keeping the carbonization temperature at 950 ℃, keeping the pressure for 5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 300-mesh screen, adding distilled water with the volume being 3 times of that of the crushed attapulgite, performing ultrasonic dispersion for 15min at the frequency of 800kHz, performing centrifugal treatment for 20min at the rotating speed of 1500r/min, collecting precipitates, and performing drying treatment; through ultrasonic dispersion and centrifugal separation treatment on the attapulgite, the content of impurities in the attapulgite can be effectively reduced, so that the permeability and the adsorption property of pore channels contained in the attapulgite are improved; finally, adding 45% by volume of a 9% mass concentration sulfuric acid solution into the dried precipitate, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1350 ℃ to calcine for 5 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:4, and adjusting the water content of the mixture to 11 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-3.5 mm by a disc granulator; finally, drying the granular material at the temperature of 60 ℃ for 5 hours to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the soil of the farmland polluted by lead and cadmium, then adjusting the humidity of the soil of the farmland polluted by lead and cadmium to 45%, finally spreading sepiolite powder into the soil of the farmland polluted by lead and cadmium according to the proportion of 90 kg/mu, and maintaining for 9 days by using waterproof cloth to obtain pretreated soil;
s3-2, adding deionized water with the volume being 9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and uniformly spraying the biochar-attapulgite compounded passivator aqueous solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 350 kg/mu, turning over, and maintaining for 20 days to complete passivation of the lead and cadmium polluted farmland soil.
Example 4: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing charcoal;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 3 hours at the temperature of 80 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-4 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with 8% of FeSO 4 Uniformly mixing the solution according to the volume ratio of 1:3, then carrying out ultrasonic treatment for 5h at the ultrasonic frequency of 500kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 0.4MPa, keeping the carbonization temperature to be 450 ℃, keeping the pressure for 2 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 100-mesh screen, adding 25% by volume of a sulfuric acid solution with the mass concentration of 5% into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 800 ℃ to calcine for 2 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:2, and adjusting the water content of the mixture to 5 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 3.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 50 ℃ for 2h to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the soil surface of the lead-cadmium polluted farmland, excavating and transferring the lead-cadmium polluted soil according to the lead-cadmium polluted depth of the soil, paving a barrier cloth in the excavated farmland, and finally backfilling the lead-cadmium polluted soil; the migration of lead and cadmium pollutants in the soil can be effectively avoided; then, applying an organic fertilizer into the soil of the lead-cadmium polluted farmland, wherein the organic fertilizer is one of chicken manure, cow manure and sheep manure; by applying the organic fertilizer to the lead-cadmium polluted farmland soil, the effects of adjusting the pH value of the soil and reducing the bioavailability and the mobility of heavy metals in the soil can be achieved, and meanwhile, the cation exchange capacity of the soil can be increased; then adjusting the humidity of the soil of the lead-cadmium polluted farmland to be 20%, finally scattering sepiolite powder into the soil of the lead-cadmium polluted farmland according to the proportion of 30 kg/mu, and curing for 5 days by using waterproof cloth to obtain pretreated soil; uniformly spraying microbial liquid to the surface of the pretreated soil, wherein the spraying amount of the microbial liquid is 1 kg/mu, and the microbial liquid is prepared by compounding photosynthetic bacteria liquid, bacillus brevis liquid, saccharomycete liquid, bacillus thuringiensis liquid, bacillus subtilis and lactobacillus liquid according to the volume ratio of 1:2:1:3:2: 2; by uniformly spraying the microbial liquid on the surface of the pretreated soil, the remediation efficiency of the cadmium-polluted soil can be improved, and meanwhile, the organic matter and microorganism content in the soil can be improved;
s3-2, adding deionized water with the volume 5 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and uniformly spraying the biochar-attapulgite compounded passivator aqueous solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 150 kg/mu, turning over, and maintaining for 15 days to complete passivation of the lead and cadmium polluted farmland soil.
Example 5: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing charcoal;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 5 hours at the temperature of 110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 3-5 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 13% 4 Uniformly mixing the solution according to the volume ratio of 1:7, then carrying out ultrasonic treatment for 15h at the ultrasonic frequency of 900kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 1.1MPa, keeping the carbonization temperature at 950 ℃, keeping the pressure for 5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 300-mesh screen, adding 45 volume percent of sulfuric acid solution with the mass concentration of 9 percent into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1350 ℃ to calcine for 5 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:4, and adjusting the water content of the mixture to 11 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 3.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 60 ℃ for 5 hours to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to 45%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 90 kg/mu, and maintaining for 9 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water 9 times the volume of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; uniformly spraying the biochar-attapulgite compounded passivator water solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 350 kg/mu, turning over, and planting ryegrass on the surface of the pretreated soil at the row spacing of 5 cm; through planting ryegrass, the lead-cadmium heavy metal pollutants in the soil are effectively adsorbed by utilizing the enrichment effect of plants, and after 20 days of maintenance, the passivation of the lead-cadmium polluted farmland soil can be completed.
Example 6: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 5 hours at the temperature of 110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 3-5 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 13% 4 Uniformly mixing the solution according to the volume ratio of 1:7, then carrying out ultrasonic treatment for 15h at the ultrasonic frequency of 900kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 1.1MPa, keeping the carbonization temperature at 950 ℃, keeping the pressure for 5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 300-mesh screen, adding 45 volume percent of sulfuric acid solution with the mass concentration of 9 percent into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1350 ℃ to calcine for 5 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:4, and adjusting the water content of the mixture to 11 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 3.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 60 ℃ for 5 hours to obtain a biochar-attapulgite compound passivator; adding a 1, 2-dimethoxyethane surfactant into the biochar-attapulgite compound passivator, controlling the pH of a reaction system to be 5, and mechanically stirring for 15min to obtain a modified biochar-attapulgite compound passivator; wherein, the adding amount of the 1, 2-dimethoxyethane surfactant is 7 wt% of the biochar-attapulgite compound passivator; by adding the surfactant into the charcoal-attapulgite compounded passivator, the adsorption capacity of the passivator on lead and cadmium heavy metal pollutants can be improved;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to 45%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 90 kg/mu, and maintaining for 9 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume being 9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; and uniformly spraying the biochar-attapulgite compounded passivator aqueous solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 350 kg/mu, turning over, and maintaining for 20 days to finish the remediation of the lead-cadmium polluted farmland soil.
Example 7: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 4 hours at the temperature of 110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-3 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 13% 4 Uniformly mixing the solution according to the volume ratio of 1:7, then carrying out ultrasonic treatment for 15h at the ultrasonic frequency of 900kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 1.1MPa, keeping the carbonization temperature at 950 ℃, keeping the pressure for 5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 300-mesh screen, adding 45 volume percent of sulfuric acid solution with the mass concentration of 9 percent into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1350 ℃ to calcine for 5 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:4, and adjusting the water content of the mixture to 5 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-3.5 mm by a disc granulator; finally, drying the granular material at the temperature of 60 ℃ for 5 hours to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of the lead-cadmium polluted farmland soil, adjusting the humidity of the lead-cadmium polluted farmland soil to 45%, finally scattering sepiolite powder into the lead-cadmium polluted farmland soil according to the proportion of 90 kg/mu, and maintaining for 9 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume being 9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; adding an activating solution with the volume of 5% into the biochar-attapulgite compounded passivator aqueous solution, and uniformly stirring; the activating solution is formed by mixing humic acid, sodium polyacrylate and deionized water according to the volume ratio of 1:3: 6; the activation solution is added, so that the forms of lead and cadmium heavy metals in the soil can be converted; meanwhile, humic acid can interact with heavy metal ions in the soil, so that the heavy metal pollution condition in the soil is improved; then uniformly spraying the biochar-attapulgite compound passivator aqueous solution added with the activating solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 350 kg/mu, turning over, and maintaining for 15 days to complete the passivation of the lead-cadmium polluted farmland soil;
example 8: the method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding comprises the following steps:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 4 hours at the temperature of 110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-3 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with FeSO with the mass concentration of 13% 4 Uniformly mixing the solution according to the volume ratio of 1:7, then carrying out ultrasonic treatment for 15h at the ultrasonic frequency of 900kHz, and finally filtering out FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 1.1MPa, keeping the carbonization temperature at 950 ℃, keeping the pressure for 5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar; wherein, in the carbonization process of the modified material, the modified material is continuously fed into the carbonization tank for 15m 3 Introducing mixed gas of oxygen and sulfur dioxide according to the volume ratio of 1:5 into the gas inlet flow of/h; the mixed gas of oxygen and sulfur dioxide is introduced into the carbonization tank, so that the thermal decomposition of the biomass in the modified material under the mixed atmosphere is facilitated, and the microporous structure of the biochar is further enlarged; soaking the biochar in 35 vol% titanium dioxide dispersion, and keeping mixingThe system temperature is 60 ℃, then magnetic stirring is carried out for 30min at the speed of 350rpm/min, after soaking is finished, titanium dioxide dispersion liquid is filtered, and the biochar is calcined for 45min in a tubular furnace at the temperature of 900 ℃; obtaining the biological carbon loaded with titanium dioxide; by loading titanium dioxide on the biochar and utilizing the photocatalytic oxidation effect of the titanium dioxide, organic pollutants adsorbed in the biochar except heavy metal ions can be decomposed, so that the effective action time of the biochar is prolonged;
s2, compounding with charcoal-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a 300-mesh screen, adding distilled water with the volume 5 times of that of the crushed attapulgite, performing ultrasonic dispersion for 30min at the frequency of 1500kHz, performing centrifugal treatment for 40min at the rotating speed of 3000r/min, collecting precipitates, and drying; through carrying out ultrasonic dispersion and centrifugal separation to the attapulgite and handling, can effectively reduce the content of impurity in the attapulgite to improve pore permeability and the adsorption efficiency that the attapulgite contains. Finally, adding a sulfuric acid solution with the volume of 45% and the mass concentration of 9% into the attapulgite precipitate, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 1350 ℃ to calcine for 5 hours to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the titanium dioxide loaded biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1:4, and adjusting the water content of the mixture to 5 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-3.5 mm by a disc granulator; finally, drying the granular material at the temperature of 60 ℃ for 5 hours to obtain a biochar-attapulgite compound passivator; adding 1, 2-dimethoxyethane surfactant into the biochar-attapulgite compound passivator, controlling the pH of a reaction system to be 8, and mechanically stirring for 30min to obtain a modified biochar-attapulgite compound passivator; wherein, the adding amount of the 1, 2-dimethoxyethane surfactant is 11 wt% of the biochar-attapulgite compound passivator; by adding the surfactant into the biochar-attapulgite compounded passivator, the adsorption capacity of the passivator on lead-cadmium heavy metal pollutants can be improved;
s3, passivating and repairing the polluted soil;
s3-1, cleaning up impurities on the surface of lead-cadmium polluted farmland soil, excavating and transferring the lead-cadmium polluted soil according to the lead-cadmium polluted depth of the soil, paving a barrier cloth in the excavated farmland, and finally backfilling the lead-cadmium polluted soil; the migration of lead and cadmium pollutants in the soil can be effectively avoided; then, applying an organic fertilizer into the soil of the lead-cadmium polluted farmland, wherein the organic fertilizer is one of chicken manure, cow manure and sheep manure; by applying the organic fertilizer to the lead-cadmium polluted farmland soil, the effects of adjusting the pH value of the soil and reducing the bioavailability and the mobility of heavy metals in the soil can be achieved, and meanwhile, the cation exchange capacity of the soil can be increased; finally, adjusting the humidity of the soil of the lead-cadmium polluted farmland to be 45%, finally scattering sepiolite powder into the soil of the lead-cadmium polluted farmland according to the proportion of 90 kg/mu, and maintaining for 9 days by using waterproof cloth; obtaining the pretreated soil; uniformly spraying a microbial liquid on the surface of the pretreated soil, wherein the spraying amount of the microbial liquid is 4 kg/mu, and the microbial liquid is prepared by compounding photosynthetic bacteria liquid, brevibacillus brevis liquid, saccharomycete liquid, bacillus thuringiensis liquid, bacillus subtilis and lactobacillus liquid according to the volume ratio of 1:2:1:3:2: 2; by uniformly spraying the microbial liquid on the surface of the pretreated soil, the remediation efficiency of the cadmium-polluted soil can be improved, and meanwhile, the organic matter and microorganism content in the soil can be improved;
s3-2, adding deionized water with the volume being 9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; adding 11% of activating solution by volume into the biochar-attapulgite compound passivator aqueous solution, and uniformly stirring; the activating solution is formed by mixing humic acid, sodium polyacrylate and deionized water according to the volume ratio of 1:3: 6; the activation solution is added, so that the forms of lead and cadmium heavy metals in the soil can be converted; meanwhile, humic acid can interact with heavy metal ions in the soil, so that the heavy metal pollution condition in the soil is improved; uniformly spraying the biochar-attapulgite compound passivator water solution added with the activating solution on the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 350 kg/mu, turning over, and planting ryegrass on the surface of the pretreated soil at the row spacing of 15 cm; by planting ryegrass, the lead and cadmium heavy metal pollutants in soil are effectively adsorbed by utilizing the enrichment effect of plants; after 15 days of maintenance, the passivation of the lead and cadmium polluted farmland soil can be completed.
Test example:
firstly, taking a lead-cadmium polluted farmland around a lead-zinc ore of Yunnan Langpen as a test sample plot, and passivating the polluted soil in the same area of the test sample plot by using the methods of the embodiments 1 to 8 of the invention respectively; before treatment, the concentration of each heavy metal pollutant in the polluted soil is measured and shown in table 1;
TABLE 1 concentration of each pollutant in lead-cadmium contaminated Farmland soil
Figure GDA0003476697050000161
Secondly, after the treatment is finished, carrying out a heavy metal leaching test on the treated lead-cadmium polluted farmland soil; the method comprises the following steps:
randomly collecting 24 parts of soil samples with the mass of 200g, then randomly dividing the 24 parts of soil samples into 8 groups with equal mass, respectively placing the soil samples of each group in 2L extraction bottles, and adding a nitric acid solution leaching agent according to a solid-liquid ratio of 10:1 (L/kg); covering tightly, fixing on a turnover type oscillation device, adjusting the rotation speed to 32r/min, oscillating for 18h at 25 ℃, standing, taking out each soil sample, centrifuging for 5min at 5000rpm on a high-speed centrifuge, taking supernatant, and storing at 4 ℃;
diluting the supernatants of the groups, measuring the concentration of lead and cadmium by utilizing ICP-MS (inductively coupled plasma-mass spectrometry), and calculating the average value of the concentration of pollutants in the soil samples of the groups; the calculation results are shown in table 2:
TABLE 2 influence of the passivation method of each example on the concentration of heavy metal pollutants in lead-cadmium contaminated farmland soil
Figure GDA0003476697050000171
Fourthly, analyzing test results;
as can be seen from the data in table 1, in example 2, compared with example 1, the introduction of the mixed gas of oxygen and sulfur dioxide into the carbonization tank contributes to the thermal decomposition of the biomass in the modified material in the mixed atmosphere, thereby further enlarging the microporous structure of the biochar; by loading titanium dioxide on the biochar and utilizing the photocatalytic oxidation of the titanium dioxide, organic pollutants adsorbed in the biochar except heavy metal ions can be decomposed, so that the effective acting time of the biochar is prolonged; compared with the embodiment 1, the embodiment 3 has the advantages that the content of impurities in the attapulgite can be effectively reduced by performing ultrasonic dispersion and centrifugal separation treatment on the attapulgite, so that the pore permeability and the adsorption performance of the attapulgite are improved; compared with the embodiment 1, the embodiment 4 has the advantages that the organic fertilizer is applied to the lead-cadmium polluted farmland soil, so that the effects of adjusting the pH value of the soil and reducing the bioavailability and the mobility of heavy metals in the soil can be achieved, the cation exchange capacity of the soil can be increased, and the migration of lead-cadmium pollutants in the soil can be effectively avoided by paving the barrier cloth in the excavated farmland; by uniformly spraying the microbial liquid on the surface of the pretreated soil, the remediation efficiency of the cadmium-polluted soil can be improved, and meanwhile, the organic matter and microorganism content in the soil can be improved; compared with the embodiment 1, the embodiment 5 effectively adsorbs lead and cadmium heavy metal pollutants in soil by planting ryegrass and utilizing the enrichment effect of plants; compared with the embodiment 1, the embodiment 6 has the advantages that the surface active agent is added into the biochar-attapulgite compound passivator, so that the adsorption capacity of the passivator on lead and cadmium heavy metal pollutants can be improved; compared with the embodiment 1, the embodiment 7 has the advantages that the activating solution is added into the biochar-attapulgite compound passivator aqueous solution, so that the transformation effect on the forms of lead and cadmium heavy metals in soil can be realized; meanwhile, humic acid can interact with heavy metal ions in the soil, so that the heavy metal pollution condition in the soil is improved; compared with the embodiments 1 to 7, the embodiment 8 integrates and optimizes all the favorable conditions, so that the passivation effect of the lead-cadmium polluted farmland soil is optimal.

Claims (4)

1. The method for passivating the lead-cadmium polluted farmland soil based on biochar-attapulgite compounding is characterized by comprising the following steps of:
s1, preparing biochar;
s1-1, removing rotten layers on the surfaces of the waste wood, then drying for 3-5 hours at the temperature of 80-110 ℃, and finally crushing the dried waste wood into wood particles with the particle size of 2-5 mm;
s1-2, mixing the wood particles obtained in the step S1-1 with 8-13% of FeSO 4 Uniformly mixing the solution according to the volume ratio of 1: 3-7, carrying out ultrasonic treatment for 5-15 h at the ultrasonic frequency of 500-900 kHz, and finally filtering out the FeSO 4 Dissolving, and washing the wood particles to be neutral to obtain a modified material;
s1-3, placing the modified material obtained in the step S1-2 into a carbonization tank, controlling the pressure in the carbonization tank to be 0.4-1.1 MPa, the carbonization temperature to be 450-950 ℃, maintaining the pressure for 2-5 hours, and naturally cooling the modified material in the carbonization tank to obtain the required biochar;
s2, compounding with biochar-attapulgite;
s2-1, crushing attapulgite, screening the crushed attapulgite by a screen of 100-300 meshes, adding 25-45% by volume of sulfuric acid solution with the mass concentration of 5-9% into the crushed attapulgite, and uniformly stirring to obtain acidified attapulgite powder; finally, placing the acidified attapulgite powder into a muffle furnace at 800-1350 ℃ for calcining for 2-5 h to obtain heat-treated attapulgite powder;
s2-2, uniformly stirring and mixing the biochar obtained in the step S1-3 and the heat-treated attapulgite powder obtained in the step S2-1 according to the volume ratio of 1: 2-4, and adjusting the water content of the mixture to 5-11 wt% by using deionized water to obtain a wet mixture; then preparing the wet mixture into granules with the particle size of 2.5-4.5 mm by a disc granulator; finally, drying the granular material at the temperature of 50-60 ℃ for 2-5 h to obtain a biochar-attapulgite compound passivator;
s3, passivating and repairing the polluted soil;
s3-1, clearing impurities on the surface of the soil of the farmland polluted by lead and cadmium, then adjusting the humidity of the soil of the farmland polluted by lead and cadmium to be 20-45%, finally scattering sepiolite powder into the soil of the farmland polluted by lead and cadmium according to the proportion of 30-90 kg/mu, and maintaining for 5-9 days by using waterproof cloth; obtaining the pretreated soil;
s3-2, adding deionized water with the volume 5-9 times that of the charcoal-attapulgite compound passivator obtained in the step S2-2, and uniformly stirring to obtain a charcoal-attapulgite compound passivator aqueous solution; uniformly spraying the biochar-attapulgite compounded passivator aqueous solution onto the surface of the pretreated soil obtained in the step S3-1 according to the proportion of 150-350 kg/mu, turning over, and maintaining for 15-20 days to complete passivation of the soil of the lead-cadmium polluted farmland;
in the step S2-1, after the attapulgite is crushed, adding distilled water with the volume 3-5 times of that of the attapulgite, performing ultrasonic dispersion for 15-30 min at the frequency of 800-1500 kHz, then performing centrifugal treatment for 20-40 min at the rotating speed of 1500-3000r/min, collecting precipitates, and performing drying treatment;
after the step S3-1 is finished, uniformly spraying microbial bacteria liquid to the surface of the pretreated soil, wherein the spraying amount of the microbial bacteria liquid is 1-4 kg/mu, and the microbial bacteria liquid is prepared by compounding photosynthetic bacteria liquid, brevibacillus brevis liquid, saccharomycete liquid, bacillus thuringiensis liquid, bacillus subtilis and lactobacillus liquid according to the volume ratio of 1:2:1:3:2: 2;
after the step S2-2 is completed, adding 1, 2-dimethoxyethane surfactant into the biochar-attapulgite compound passivator, controlling the pH of a reaction system to be 5-8, and mechanically stirring for 15-30 min to obtain a modified biochar-attapulgite compound passivator; wherein the adding amount of the 1, 2-dimethoxyethane surfactant is 7-11 wt% of the biochar-attapulgite compound passivator;
in the step S3-2, adding an activating solution with the volume of 5-11% into the biochar-attapulgite compound passivator aqueous solution, and uniformly stirring; the activating solution is prepared by mixing humic acid, sodium polyacrylate and deionized water according to the volume ratio of 1:3: 6;
in the step S1-3, in the carbonization process of the modified material, the modified material is continuously fed into a carbonization tank for 5-15 m 3 Introducing mixed gas of oxygen and sulfur dioxide in a volume ratio of 1: 2-5 into the gas inlet flow per hour;
after the step S1-3 is finished, soaking the biochar in a titanium dioxide dispersion liquid with the volume concentration of 15-35%, keeping the temperature of a mixed system at 45-60 ℃, then magnetically stirring at the speed of 150-350 rpm for 15-30 min, after soaking is finished, filtering out the titanium dioxide dispersion liquid, and calcining the biochar in a tubular furnace at the temperature of 500-900 ℃ for 25-45 min; obtaining the biochar loaded with titanium dioxide.
2. The method for passivating lead-cadmium contaminated farmland soil based on biochar-attapulgite compounding of claim 1, which is characterized in that in step S3-1, after the lead-cadmium contaminated farmland is cleaned, an organic fertilizer is applied to the lead-cadmium contaminated farmland soil, wherein the organic fertilizer is one of chicken manure, cow manure and sheep manure.
3. The method for passivating lead-cadmium contaminated farmland soil based on biochar-attapulgite compounding as claimed in claim 1, wherein in step S3-1, after the cleaning of impurities on the surface of the lead-cadmium contaminated farmland soil is completed, the excavation and transfer of the lead-cadmium contaminated soil are performed according to the lead-cadmium contaminated depth of the soil, and a barrier cloth is laid in the excavated farmland, and finally the lead-cadmium contaminated soil is backfilled.
4. The method for passivating the soil of the lead-cadmium polluted farmland based on the biochar-attapulgite combination according to claim 1, characterized in that, in the step S3-2, ryegrass is planted on the surface of the pretreated soil at a row spacing of 5-15 cm after the pretreated soil is ploughed.
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* Cited by examiner, † Cited by third party
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CN114606006B (en) * 2022-03-29 2023-10-27 中陕高标准农田建设集团有限公司 Composition for passivating soil heavy metals
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CN116636346A (en) * 2023-05-24 2023-08-25 重庆千洲生态环境工程有限公司 Vegetation ecological restoration method under ecological induction of riverbank
CN116855254B (en) * 2023-07-03 2024-06-07 江苏莘野生物科技有限公司 Long-acting controllable acid soil conditioner and preparation method thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105384211A (en) * 2015-11-19 2016-03-09 兰州交通大学 Acid heat treatment attapulgite water quality purifying agent
CN106824083A (en) * 2017-04-10 2017-06-13 东南大学 A kind of preparation method and applications of attapulgite/biomass carbon compound adsorbent
CN108728101A (en) * 2018-07-06 2018-11-02 兰州坤仑环保科技有限公司 Attapulgite-based soil heavy metal restoration agent
CN110217772A (en) * 2019-05-13 2019-09-10 中山大学 A kind of modification biological charcoal and its preparation method and application
CN111807453A (en) * 2020-07-17 2020-10-23 长沙理工大学 Modified biochar for adsorbing phosphorus in water body and preparation method and application thereof
CN112892475A (en) * 2021-01-15 2021-06-04 仲恺农业工程学院 Iron modified biochar and preparation method and application thereof
AU2021103819A4 (en) * 2021-07-02 2021-08-26 Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences Modified biochar and preparation method and application thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105524623B (en) * 2016-02-01 2017-02-22 广东省生态环境与土壤研究所（广东省土壤科学博物馆） Preparation and use methods of slow-release type iron-based biochar soil heavy metal passivator

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105384211A (en) * 2015-11-19 2016-03-09 兰州交通大学 Acid heat treatment attapulgite water quality purifying agent
CN106824083A (en) * 2017-04-10 2017-06-13 东南大学 A kind of preparation method and applications of attapulgite/biomass carbon compound adsorbent
CN108728101A (en) * 2018-07-06 2018-11-02 兰州坤仑环保科技有限公司 Attapulgite-based soil heavy metal restoration agent
CN110217772A (en) * 2019-05-13 2019-09-10 中山大学 A kind of modification biological charcoal and its preparation method and application
CN111807453A (en) * 2020-07-17 2020-10-23 长沙理工大学 Modified biochar for adsorbing phosphorus in water body and preparation method and application thereof
CN112892475A (en) * 2021-01-15 2021-06-04 仲恺农业工程学院 Iron modified biochar and preparation method and application thereof
AU2021103819A4 (en) * 2021-07-02 2021-08-26 Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences Modified biochar and preparation method and application thereof

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue;Xianlong Zhang 等;《Journal of environmental sciences》;20150531;第97-105页 *
凹凸棒石/脱硅稻壳炭复合材料吸附Pb2+、Cu2+、Ni2+的对比研究;刘文杰等;《化工新型材料》;20150531;第43卷(第5期);第169-173页 *
生物炭-凹凸棒土复合材料对水稻土锌镉的钝化及土壤养分和酶活性的影响研究;尤凌聪等;《核农学报》;20210710;第35卷(第7期);第1717-1723页 *

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