A soil remediation agent for treating heavy metal pollution and preparation method thereof

Abstract

The present invention belongs to the technical field of soil remediation, and specifically relates to a soil remediation agent for treating heavy metal pollution and a preparation method thereof. The preparation method comprises the following steps: (1) heat-treating sepiolite to obtain heat-treated sepiolite; (2) acid-treating the biomass, then rinsing with deionized water until the solution is neutral, and drying in a vacuum oven to obtain product A, ultrasonically dispersing product A, iron salt, cerium salt, yttrium salt, copper salt and manganese salt in methanol to obtain solution B, dispersing dimethylimidazole into solution C in methanol, and then adding solution C to solution B to mix, stir, filter, wash, and vacuum dry to obtain product D; (3) mechanically mixing the heat-treated sepiolite obtained in step (1), product D obtained in step (2) and diatomaceous earth, heat-treating, cooling to room temperature, and obtaining a remediation agent. The soil remediation agent of the present invention can effectively remediate heavy metals in the soil, and has the characteristics of good removal effect and high removal rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil modification, and more specifically, relates to a soil remediation agent for treating heavy metal pollution and a preparation method thereof. Background Art

[0002] Soil heavy metal and organic pollution has always been a major environmental problem that has plagued global sustainable development. With the rapid development of economy and industry and agriculture, such environmental problems urgently need to seek breakthroughs in basic theory and technology. As a porous material, biochar has become a very promising soil conditioner due to its high carbon content and rich functional groups. It can improve soil structure and increase soil nutrient content, and has been proven to play a role in soil improvement and fertilization. Biochar is produced by burning biomass in a limited oxygen environment and at relatively low temperatures (<700℃). The properties of biochar depend largely on the type of raw material. Its carbon content generally exceeds 50% (except for biochar from feces (44.3%), sewage sludge (39.6%) and paper sludge (8.15%)), and some materials can even reach 70% to 80%; at the same time, it presents an aromatic carbon structure, including crystalline and amorphous phases. Due to its porous structure and rich surface functional groups, biochar can effectively reduce the bioavailability of heavy metals and promote the degradation of organic pollutants. Reasonable application of functional biochar materials can not only reduce pollution risks but also improve soil quality. It is a "kill two birds with one stone" restoration strategy to solve various environmental problems and has been applied in engineering.

[0003] CN115975646A discloses a method for preparing a biochar soil remediation agent, comprising the following steps: 1) using rice husk as a raw material, drying and crushing it, and then performing anaerobic carbonization to obtain biochar; 2) adding the biochar to a magnesium salt solution and stirring it, then heating it in a water bath to 70-90°C and adding a carbonate solution and continuing to stir, rinsing and drying to obtain silicon-activated biochar; 3) adding the silicon-activated biochar to a hydroxyl-modified solution and stirring and reacting for 2-5 hours to obtain a biochar soil remediation agent. The present invention realizes efficient fixation of soil heavy metals by silicon activation and combined hydroxyl modification of biochar, and can effectively reduce the biological effectiveness of passivated soil heavy metals through complexation, precipitation and other effects.

[0004] CN115960611A discloses a contaminated soil remediation agent and its preparation method and application. The preparation method of the contaminated soil remediation agent provided by the present invention comprises the following steps: 1) using biomass as raw material, grinding, drying and roasting to obtain biochar; 2) mixing the biochar in step 1) with calcium-based materials and water, stirring, centrifuging, washing and drying to obtain calcium-based modified biochar; 3) in an anaerobic environment, dripping the mixed solution formed by mixing the iron-based solution and the carboxymethyl cellulose solution into the reducing agent solution, stirring the reaction, centrifuging, washing, drying and grinding to obtain a carboxymethyl cellulose-nano iron composite material; 4) mixing the above-mentioned calcium-based modified biochar and the above-mentioned carboxymethyl cellulose-nano iron composite material and ball milling to obtain the contaminated soil remediation agent. The contaminated soil remediation agent obtained by this preparation method can simultaneously and efficiently repair soil fluorine and chromium pollution, and the repair effect is stable.

[0005] CN115637150A discloses a method for preparing iron-manganese modified biochar for cadmium-contaminated soil remediation, including: (1) crushing crop straw; (2) introducing nitrogen into the straw powder for anaerobic calcination to obtain straw biochar, then placing it in a dilute nitric acid solution, stirring and standing, washing it with deionized water for multiple times and drying it; (3) adding the straw biochar to an iron salt solution and intermittently ultrasonically treating it, then adding a manganese salt solution and treating it again under the action of intermittent ultrasonic waves, then heating and drying it in a water bath, then soaking and cleaning it with a n-propanol solution and drying it for standby use; (4) introducing nitrogen into the loaded iron-manganese biochar material for anaerobic calcination; (5) placing the prepared iron-manganese modified biochar in an ethanol solution, stirring and standing, washing it with deionized water for multiple times and then drying it. The present invention also provides an iron-manganese modified biochar prepared by the method and an application method thereof, which is suitable for the remediation and treatment of mild and moderately severe cadmium-contaminated soils, with a small application dosage, convenient operation and remarkable effect.

[0006] In summary, existing soil remediation agents have low efficiency in solidifying metal ions, and the removal effect still cannot meet the needs of actual production. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and deficiencies in the prior art, and to provide a soil remediation agent for treating heavy metal pollution and a preparation method thereof. The preparation method comprises the following steps: (1) heat-treating sepiolite to obtain heat-treated sepiolite; (2) acid-treating the biomass, then rinsing with deionized water until the solution is neutral, and drying in a vacuum oven to obtain product A, ultrasonically dispersing product A, iron salt, cerium salt, yttrium salt, copper salt and manganese salt in methanol to obtain solution B, dispersing dimethylimidazole into solution C in methanol, and then adding solution C to solution B to mix, stir, filter, wash, and vacuum dry to obtain product D; (3) mechanically mixing the heat-treated sepiolite obtained in step (1), product D obtained in step (2) and diatomaceous earth, heat-treating, cooling to room temperature, and obtaining a remediation agent. The soil remediation agent of the present invention can effectively repair heavy metals in the soil, and has the characteristics of good removal effect and high removal rate.

[0008] The purpose of the present invention is to provide a method for preparing a soil remediation agent for treating heavy metal pollution.

[0009] Another object of the present invention is to provide a soil remediation agent for treating heavy metal pollution.

[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0012] (1) heat-treating the sepiolite to obtain heat-treated sepiolite;

[0013] (2) treating the biomass with acid, then washing with deionized water until the solution is neutral, and drying in a vacuum oven to obtain product A, ultrasonically dispersing product A, iron salt, cerium salt, yttrium salt, copper salt and manganese salt in methanol to obtain solution B, dispersing dimethylimidazole in methanol to obtain solution C, and then adding solution C to solution B to mix, stir, filter, wash and vacuum dry to obtain product D;

[0014] (3) mechanically mixing the heat-treated sepiolite obtained in step (1), the product D obtained in step (2) and diatomaceous earth uniformly, 2 In the presence of, heat treatment is carried out, and cooling to room temperature is performed to obtain a repair agent.

[0015] Preferably, in step (1), the heat treatment is performed at 400-500° C. for 1-5 hours.

[0016] Preferably, in step (2), the acid treatment is treatment with nitric acid or sulfuric acid at a concentration of 2-3.0 mol / L for 2-4 hours.

[0017] Preferably, in step (2), the ratio of the product A, iron salt, cerium salt, yttrium salt, copper salt, manganese salt and dimethylimidazole is: 1g: 0.15-0.35mmol: 0.05-0.15mmol: 0.05-0.25mmol: 0.02-0.08mmol: 5mmol; 20-30mmol.

[0018] Preferably, in step (2), the stirring is performed at room temperature for 6 to 12 hours; and the biomass is peanut shells or corn stalks.

[0019] Preferably, in step (2), the vacuum drying is performed at 60 to 80° C. for 8 to 16 hours.

[0020] Preferably, in step (2), the iron salt is at least one of iron nitrate, iron chloride, and iron acetate; the cerium salt is at least one of cerium nitrate, cerium chloride, and cerium acetate; the yttrium salt is at least one of yttrium nitrate, yttrium chloride, and yttrium acetate; the copper salt is at least one of copper nitrate, copper chloride, and copper acetate; and the manganese salt is at least one of manganese nitrate, manganese chloride, and manganese acetate.

[0021] Preferably, in step (3), the mass ratio of the heat-treated sepiolite obtained in step (1), the product D obtained in step (2), and diatomaceous earth is 1:3-7:1-3.

[0022] Preferably, in step (3), the heat treatment is carried out at 0 2 When the concentration is 3-7 vol%, it is first heat treated at 150-250°C for 3-7 hours, and then heat treated at 500-600°C for 4-8 hours when the oxygen concentration is 1-3 vol%.

[0023] A soil remediation agent for treating heavy metal pollution is prepared based on the above-mentioned method for preparing a soil remediation agent for treating heavy metal pollution.

[0024] The present invention has the following beneficial effects:

[0025] (1) Acid treatment of biomass can improve the active groups on the biomass surface, which is beneficial to the adhesion of metals and improves the dispersion of metals. In addition, MOF materials can be prepared in situ and then composited with sepiolite and diatomaceous earth and then heat treated to improve the adsorption capacity of the carbonized material.

[0026] (2) The present invention utilizes the interaction between components to improve the heavy metal removal ability of the soil remediation agent.

[0027] (3) The soil remediation agent of the present invention has excellent heavy metal removal ability and has good application prospects. DETAILED DESCRIPTION

[0028] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0029] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0030] Example 1

[0031] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0032] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0033] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0034] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0035] Example 2

[0036] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0037] (1) heat treating sepiolite at 500° C. for 1 h to obtain heat-treated sepiolite;

[0038] (2) Treat corn stalks with 3.0 mol / L sulfuric acid for 3 h, then rinse with deionized water until the solution is neutral, and dry in a vacuum oven to obtain product A. Ultrasonic disperse 1 g of product A, 0.35 mmol of ferric chloride, 0.05 mmol of cerium acetate, 0.25 mmol of yttrium nitrate, 0.02 mmol of copper chloride and 5 mmol of manganese acetate in methanol to obtain solution B. Disperse 30 mmol of dimethylimidazole in 50 mL of methanol to obtain solution C. Then add solution C to solution B, stir at room temperature for 12 h, filter, wash, and vacuum dry at 80 °C for 8 h to obtain product D.

[0039] (3) 10 g of the heat-treated sepiolite obtained in step (1), 70 g of the product D obtained in step (2) and 10 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 Under the condition of oxygen concentration of 7 vol%, it was first heat treated at 250°C for 3 h, and then heat treated at 600°C for 4 h under the condition of oxygen concentration of 3 vol%, and cooled to room temperature to obtain a repair agent.

[0040] Example 3

[0041] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0042] (1) heat treating sepiolite at 400° C. for 5 h to obtain heat-treated sepiolite;

[0043] (2) The biomass was treated with 2 mol / L nitric acid for 4 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.15 mmol of ferric acetate, 0.15 mmol of cerium chloride, 0.05 mmol of yttrium acetate, 0.08 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 20 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Then solution C was added to solution B and mixed, stirred at room temperature for 6 h, filtered, washed, and vacuum dried at 60 °C for 16 h to obtain product D.

[0044] (3) 10 g of the heat-treated sepiolite obtained in step (1), 30 g of the product D obtained in step (2) and 30 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 3 vol%, it is first heat treated at 150°C for 7 hours, and then heat treated at 500°C for 8 hours when the oxygen concentration is 1 vol%, and cooled to room temperature to obtain a repair agent.

[0045] Comparative Example 1

[0046] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0047] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0048] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.35 mmol of ferric nitrate, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0049] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0050] Comparative Example 2

[0051] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0052] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0053] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.35 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate, and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed, stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0054] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0055] Comparative Example 3

[0056] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0057] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0058] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.25 mmol of cerium chloride, 0.05 mmol of copper nitrate, and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0059] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0060] Comparative Example 4

[0061] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0062] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0063] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.25 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed, stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0064] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0065] Comparative Example 5

[0066] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0067] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0068] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.2 mmol of yttrium acetate, and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0069] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0070] Comparative Example 6

[0071] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0072] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0073] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.2 mmol of copper nitrate, and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed, stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0074] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0075] Comparative Example 7

[0076] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0077] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0078] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0079] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 Under the condition of oxygen concentration of 5 vol%, it was first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h under the condition of oxygen concentration of 5 vol%, and cooled to room temperature to obtain a repair agent.

[0080] Comparative Example 8

[0081] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0082] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0083] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0084] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 2 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0085] Comparative Example 9

[0086] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0087] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0088] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0089] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth are mechanically mixed and uniformly mixed. Under an inert atmosphere, the mixture is first heat-treated at 200° C. for 5 h and then at 550° C. for 6 h. The mixture is then cooled to room temperature to obtain a repair agent.

[0090] Comparative Example 10

[0091] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0092] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0093] (2) Peanut shells were treated with 2.5 mol / L hydrochloric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0094] (3) 10 g of the heat-treated sepiolite obtained in step (1), 50 g of the product D obtained in step (2) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0095] Comparative Example 11

[0096] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0097] (1) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed, stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0098] (2) 60 g of the product D obtained in step (1) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0099] Comparative Example 12

[0100] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0101] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0102] (2) 60 g of the heat-treated sepiolite obtained in step (1) and 20 g of diatomaceous earth were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0103] Comparative Example 13

[0104] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0105] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0106] (2) Peanut shells were treated with 2.5 mol / L nitric acid for 3 h, then rinsed with deionized water until the solution was neutral, and dried in a vacuum oven to obtain product A. 1 g of product A, 0.25 mmol of ferric nitrate, 0.1 mmol of cerium chloride, 0.15 mmol of yttrium acetate, 0.05 mmol of copper nitrate and 5 mmol of manganese chloride were ultrasonically dispersed in 50 mL of methanol to obtain solution B. 25 mmol of dimethylimidazole was dispersed in 50 mL of methanol to obtain solution C. Solution C was then added to solution B and mixed. The mixture was stirred at room temperature for 10 h, filtered, washed, and vacuum dried at 70 °C for 12 h to obtain product D.

[0107] (3) 10 g of the heat-treated sepiolite obtained in step (1) and 70 g of the product D obtained in step (2) were mechanically mixed and uniformly stirred at 0.5 °C. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0108] Comparative Example 14

[0109] A method for preparing a soil remediation agent for treating heavy metal pollution, the preparation method comprising the following steps:

[0110] (1) heat treating sepiolite at 450° C. for 3 h to obtain heat-treated sepiolite;

[0111] (2) 10 g of the heat-treated sepiolite obtained in step (1) and 70 g of diatomaceous earth were mechanically mixed uniformly. 2 When the concentration is 5 vol%, it is first heat treated at 200°C for 5 h, and then heat treated at 550°C for 6 h when the oxygen concentration is 2 vol%, and cooled to room temperature to obtain a repair agent.

[0112] Contaminated soil was prepared. After determination, the actual values ​​of Cd, Pb and Cu in the contaminated soil samples were 4.2, 256 and 523 mg kg, respectively. -1 .

[0113] 500 g of the contaminated soil was weighed and placed in a 500 mL beaker. The adsorption treatment was repeated 3 times each time. 10 g of the soil contamination remediation agent of Examples 1-3 and Comparative Examples 1-14 were respectively mixed with the contaminated soil in the above proportions. Each beaker was sealed with a pierced plastic wrap and placed at room temperature for immobilization reaction. During the reaction, deionized water was added to the beaker every 5 days to keep the soil moisture content at about 30%.

[0114] The TCLP method was used to evaluate the immobilization effect of the soil remediation agents of Examples 1-3 and Comparative Examples 1-14 on soil heavy metals after 15 days and 20 days. The specific results are shown in Table 1-2. The TCLP determination was carried out according to the method in the Environmental Protection Industry Standard of the People's Republic of China (HJ / T300-2007), that is, leaching was carried out using acetic acid and sodium hydroxide buffer solution. The leaching process was as follows: 30 mL of TCLP extract (solid-liquid ratio 1:20) was added to 1.5 g of soil, and the mixture was stirred at 30 r·min. -1 The reaction was carried out on a flip-over shaker for 18 h, and then at 2000 r.min -1 The mixture was centrifuged at 400 °C for 20 min, filtered through a 0.45 μm filter membrane, and the heavy metal concentration in the supernatant was determined by inductively coupled plasma emission spectrometry (ICP). The TCLP extract was prepared by adding 5.7 mL of glacial acetic acid to distilled water and using 1 mol·L -1 NaOH and HNO 3 The pH value of the solution was adjusted to 4.9 and the volume was fixed to 1 L for later use.

[0115] Table 1 15-day immobilization effect of Examples 1-3 and Comparative Examples 1-14

[0116] Cd removal rate (%) Pd removal rate (%) Cu removal rate (%) Example 1 83.5 85.3 84.6 Example 2 82.4 84.1 83.2 Example 3 83.2 84.8 84.1 Comparative Example 1 81.5 82.6 81.8 Comparative Example 2 81.9 83.4 82.5 Comparative Example 3 81.3 82.3 81.5 Comparative Example 4 81.6 82.8 81.9 Comparative Example 5 81.4 82.5 81.6 Comparative Example 6 81.7 82.9 82.2 Comparative Example 7 81.8 83.2 82.3 Comparative Example 8 82.1 83.5 82.6 Comparative Example 9 80.9 81.9 81.1 Comparative Example 10 81.2 82.2 81.3 Comparative Example 11 75.9 81.6 76.1 Comparative Example 12 65.3 68.4 66.7 Comparative Example 13 76.3 81.8 77.4 Comparative Example 14 59.8 61.4 60.8

[0117] Table 2 20-day immobilization effects of Examples 1-3 and Comparative Examples 1-14

[0118] Cd removal rate (%) Pd removal rate (%) Cu removal rate (%) Example 1 91.4 95.3 92.6 Example 2 90.3 94.2 91.2 Example 3 90.9 94.8 91.9 Comparative Example 1 89.3 93.1 90.2 Comparative Example 2 89.9 93.7 90.8 Comparative Example 3 88.9 92.8 89.7 Comparative Example 4 89.5 93.2 90.3 Comparative Example 5 89.2 92.9 89.9 Comparative Example 6 89.6 93.4 90.5 Comparative Example 7 89.8 93.6 90.7 Comparative Example 8 90.1 93.9 90.9 Comparative Example 9 88.6 92.4 89.5 Comparative Example 10 88.8 92.6 89.6 Comparative Example 11 82.9 85.9 84.1 Comparative Example 12 73.1 74.8 74.2 Comparative Example 13 83.4 87.2 84.8 Comparative Example 14 69.2 71.5 70.1

[0119] From the comparison between Examples 1-3 and Comparative Examples 1-14, it can be seen that the soil remediation agent prepared in the present application utilizes the interaction between the components, so that the soil remediation agent of the present application has excellent curing effect and high heavy metal removal effect, and the soil remediation agent of the present invention has excellent application prospects.

[0120] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a soil remediation agent for treating heavy metal pollution, characterized in that: The preparation method comprises the following steps: (1) heat-treating the sepiolite to obtain heat-treated sepiolite; (2) treating the biomass with acid, then washing with deionized water until the solution is neutral, and drying in a vacuum oven to obtain product A, ultrasonically dispersing product A, iron salt, cerium salt, yttrium salt, copper salt and manganese salt in methanol to obtain solution B, dispersing dimethylimidazole in methanol to obtain solution C, and then adding solution C to solution B, mixing, stirring, filtering, washing, and vacuum drying to obtain product D; (3) mechanically mixing the heat-treated sepiolite obtained in step (1), the product D obtained in step (2) and diatomaceous earth, performing a heat treatment in the presence of O2, and cooling to room temperature to obtain a repairing agent; In step (2), the acid treatment is treatment with nitric acid or sulfuric acid at a concentration of 2-3.0 mol / L for 2-4 hours; In step (2), the ratio of the product A, iron salt, cerium salt, yttrium salt, copper salt, manganese salt and dimethylimidazole is: 1g: 0.15-0.35mmol: 0.05-0.15mmol: 0.05-0.25mmol: 0.02-0.08mmol: 5mmol; 20-30mmol; In step (3), the mass ratio of the heat-treated sepiolite obtained in step (1), the product D obtained in step (2), and diatomaceous earth is 1:3-7:1-3; In step (3), the heat treatment is first performed at 150-250°C for 3-7 hours at an O2 concentration of 3-7 vol%, and then at 500-600°C for 4-8 hours at an oxygen concentration of 1-3 vol%.

2. The method for preparing a soil remediation agent for treating heavy metal pollution according to claim 1, characterized in that: In step (1), the heat treatment is performed at 400-500° C. for 1-5 hours.

3. The method for preparing a soil remediation agent for treating heavy metal pollution according to claim 1, characterized in that: In step (2), the stirring is performed at room temperature for 6 to 12 hours; and the biomass is peanut shells or corn stalks.

4. The method for preparing a soil remediation agent for treating heavy metal pollution according to claim 1, characterized in that: In step (2), the vacuum drying is performed at 60 to 80° C. for 8 to 16 hours.

5. The method for preparing a soil remediation agent for treating heavy metal pollution according to claim 1, characterized in that: In step (2), the iron salt is at least one of iron nitrate, iron chloride, and iron acetate; the cerium salt is at least one of cerium nitrate, cerium chloride, and cerium acetate; the yttrium salt is at least one of yttrium nitrate, yttrium chloride, and yttrium acetate; the copper salt is at least one of copper nitrate, copper chloride, and copper acetate; and the manganese salt is at least one of manganese nitrate, manganese chloride, and manganese acetate.

6. A soil remediation agent for treating heavy metal pollution, prepared according to the method for preparing a soil remediation agent for treating heavy metal pollution according to any one of claims 1 to 5.