A method for the safe utilization of nickel-contaminated soil

Abstract

The present invention provides a method for the safe utilization of nickel-contaminated soil. The method for the safe utilization of nickel-contaminated soil according to the present invention comprises the following steps: S1: adding a pH regulator to the nickel-contaminated soil to adjust the pH value of the nickel-contaminated soil; S2: applying a nickel stabilization agent to the nickel-contaminated soil after adjusting the pH value, and rototilling and mixing evenly; S3: adjusting the water content of the nickel-contaminated soil after rototilling and mixing evenly, and covering with a film for curing; S4: carrying out crop planting after covering with a film for curing, and spraying a nickel absorption inhibitor during the crop planting period. The present invention combines the use of a pH regulator, a nickel stabilization agent and a nickel absorption inhibitor, can realize the safe utilization of nickel-contaminated soil, and has the advantages of simple operation, short cycle, good effect, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and particularly to a method for the safe utilization of nickel-contaminated soil. Background Art

[0002] Nickel is a heavy metal element commonly used in industrial production, mainly for stainless steel manufacturing, electroplating, and battery production. It is estimated that human activities and industrial production emit approximately 150,000 - 180,000 tons of nickel into the environment each year. According to the results of the national soil pollution survey, the nickel point exceedance rate ranks second in the national soil pollution, with an exceedance rate as high as 4.8%. Nickel entering the soil environment will cause serious harm to the soil ecosystem. After being absorbed by crops in the soil, it will ultimately enter the human body through the food chain, posing a great risk to human health and easily causing diseases such as pulmonary fibrosis, renal dysfunction, cardiovascular diseases, and respiratory diseases.

[0003] The remediation and safe utilization of nickel-contaminated soil are important measures to ensure ecological environment and human health and safety. Currently, the main measures for heavy metal pollution remediation include solidification / stabilization, chemical leaching, phytoremediation, microbial remediation, etc.; among them, the solidification / stabilization technology has advantages such as low investment, rapid remediation, simple operation, and not being restricted by soil types, and is easy to achieve large-scale, high-efficiency, and low-cost remediation of heavy metal-contaminated soil. However, most of the existing nickel-contaminated soil remediation methods have problems such as poor solidification / stabilization effects and cannot improve the safe utilization efficiency of nickel-contaminated soil.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for the safe utilization of nickel-contaminated soil, which realizes the safe utilization of nickel-contaminated soil by combining a pH regulator, a nickel stabilization agent, and a nickel absorption inhibitor.

[0006] The present invention provides a method for the safe utilization of nickel-contaminated soil, including the following steps:

[0007] S1: Adding a pH regulator to the nickel-contaminated soil to adjust the pH value of the nickel-contaminated soil;

[0008] S2: Applying a nickel stabilization agent to the nickel-contaminated soil after adjusting the pH value, and rotary tilling and mixing evenly;

[0009] S3: Adjusting the water content of the nickel-contaminated soil after rotary tilling and mixing evenly, and covering with a film for curing;

[0010] S4: Conducting crop planting after covering with a film for curing, and spraying a nickel absorption inhibitor during the crop planting period.

[0011] In step S1, a pH regulator is added at least 40 days before planting crops; the pH regulator is selected from at least one of MgCO 3 and CaCO 3 ; the pH value of the nickel-contaminated soil is adjusted to 7 - 7.5. Research shows that adjusting the pH value of the nickel-contaminated soil to 7 - 7.5 is beneficial to improving the stabilization effect of the nickel-contaminated soil.

[0012] In step S2, the nickel stabilizer is prepared by ball milling after mixing modified clay minerals and humic acid; the mass ratio of modified clay minerals to humic acid in the nickel stabilizer is (8.5 - 9.5):(0.5 - 1.5); the ball milling time is 1.5 - 2.5 h; the application amount of the nickel stabilizer is 2 - 5%, that is, 2 - 5 kg of the nickel stabilizer is applied per 100 kg of the dry weight of the plough layer soil.

[0013] Specifically, the modification method of the modified clay minerals includes alkali modification, and the alkali modification includes:

[0014] Drying, grinding, and sieving the natural clay minerals, then mixing them evenly with a sodium hydroxide solution of 0.125 - 0.5 mol / L according to a solid-liquid ratio of 1:(8 - 12), carrying out oscillation treatment at 70 - 90 °C for 6 - 8 h, centrifuging, washing, drying, grinding, and sieving to obtain alkali-modified clay minerals; among them, the natural clay minerals can be natural aluminous clay minerals such as natural montmorillonite, kaolinite, zeolite, etc.; the centrifugation speed is 2500 - 3500 r / min, and the centrifugation time is 4 - 6 min.

[0015] The modification method of the modified clay minerals also includes sulfur modification, and the sulfur modification includes:

[0016] Mixing the alkali-modified clay minerals evenly with a sulfur activator solution with a sulfur content of 0.05 - 0.15 mol / L according to a solid-liquid ratio of 1:(8 - 12), then carrying out hydrothermal reaction at 150 - 180 °C for 12 - 20 h, centrifuging, washing, drying, grinding, and sieving to obtain modified clay minerals; among them, the sulfur activator solution is a solution of Na 2 S 2 O 4 、Na 2 S 2 O 3 、Na 2 S, etc.; the centrifugation speed is 2500 - 3500 r / min, and the centrifugation time is 4 - 6 min.

[0017] The above nickel stabilization agent mainly reduces the content of available nickel through physicochemical adsorption, precipitation and other effects, thereby reducing its spread in the ecosystem. Among them, alkali modification is used to reduce the Si / Al ratio to improve the exchange performance of the nickel stabilization agent; sulfur modification is used to form nickel sulfide precipitation to improve the stabilization efficiency of the nickel stabilization agent. In addition, research shows that the stabilization efficiency of pure modified clay minerals for nickel is generally average, and the nickel stabilization efficiency can be increased by 2-4 times after mixing with humic acid.

[0018] In step S3, the water content of the nickel-contaminated soil after rotary tillage and mixing is adjusted to 60-80% of the maximum field water holding capacity of the nickel-contaminated soil; the film covering and curing time is 25-35 days.

[0019] In step S4, a nickel absorption inhibitor is sprayed during the critical growth period of the crop. The critical growth period of the crop is determined according to the crop type, such as the initial flowering stage of cucumber, the fruit setting stage of tomato, the rosette stage of Chinese cabbage, the heading stage of wheat, the heading stage of corn, the filling stage of rice, etc.; the nickel absorption inhibitor is a proline solution with a concentration of 100-200 mmol / L; the spraying times of the proline solution are 2-3 times. Proline can play a defensive role by detoxifying reactive oxygen species to protect the membrane and stabilizing enzymes and proteins, thereby inhibiting the absorption and utilization of toxic and harmful elements by crops.

[0020] The method for safe utilization of nickel-contaminated soil of the present invention realizes the safe utilization of nickel-contaminated soil by combining a pH regulator, a nickel stabilization agent and a nickel absorption inhibitor, and has the advantages of simple operation, short cycle, good effect, etc. Detailed Description of the Invention

[0021] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms also include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0023] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] The method for safely utilizing nickel - contaminated soil in this example includes the following steps:

[0026] S1: Adjust the pH value

[0027] At least 40 days before planting crops, add MgCO 3 Adjust the pH value of the nickel - contaminated soil to between 7 and 7.5.

[0028] S2: Apply nickel stabilization agent

[0029] Dry, grind, and sieve kaolinite, then mix it evenly with 0.3 mol / L sodium hydroxide solution at a solid - liquid ratio of 1:10, place it in a constant - temperature oscillator and oscillate at 80 °C for 7 h, centrifuge at 3000 r / min for 5 min to separate sodium hydroxide and clay minerals, wash with deionized water, centrifuge and separate, repeat the washing and centrifugation 3 - 5 times until OH cannot be detected in the supernatant - Stop. Dry, grind, and sieve the kaolinite after centrifugation and separation to obtain alkali - modified clay minerals.

[0030] Mix the alkali - modified clay minerals evenly with Na 2 S 2 O 4 solution at a solid - liquid ratio of 1:10, transfer it to a reaction kettle, place it in an oven and carry out hydrothermal reaction at 165 °C for 16 h, then centrifuge at 3000 r / min for 5 min, wash repeatedly with deionized water, dry, grind, and sieve to obtain modified clay minerals.

[0031] Mix 90 parts of the above - mentioned modified clay minerals evenly with 10 parts of humic acid, place them in a ball mill and ball - mill for 2 h to obtain a nickel stabilization agent.

[0032] Apply the above - mentioned nickel stabilization agent to the nickel - contaminated soil after adjusting the pH value at a mass ratio of 3.5%, and rotary till and mix evenly.

[0033] S3: Adjust the water content and cover with film for curing

[0034] Adjust the water content of the nickel - contaminated soil after rotary tilling and mixing to 70% of the maximum field water - holding capacity of the soil, and cover with film for curing for 30 days.

[0035] After the curing is completed, collect soil samples, air - dry naturally, grind and sieve, and analyze and test the contents of various forms of nickel. The results are shown in Table 1.

[0036] S4: Crop planting

[0037] After the available nickel content reaches the expected target, spinach is planted, and a 150 mmol / L proline solution is sprayed twice during the vegetative growth period of spinach.

[0038] After the spinach matures, it is harvested, and the edible part of the spinach is collected to measure its nickel content. The results are shown in Table 2.

[0039] Example 2

[0040] The method for safely utilizing nickel-polluted soil in this example includes the following steps:

[0041] S1: Adjust the pH value

[0042] At least 40 days before planting crops, CaCO is added 3 The pH value of the nickel-polluted soil is adjusted to between 7 and 7.5.

[0043] S2: Apply nickel stabilization agent

[0044] The zeolite is dried, ground, and sieved, and then mixed evenly with a 0.125 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:12, placed in a constant temperature oscillator and oscillated at 70 °C for 8 h, centrifuged at 2500 r / min for 6 min to separate sodium hydroxide and clay minerals, washed with deionized water, and centrifuged and separated. Repeat the washing and centrifugation 3 - 5 times until OH is not detected in the supernatant - Then, the centrifuged zeolite is dried, ground, and sieved to obtain alkali-modified clay minerals.

[0045] Mix the alkali-modified clay minerals with a Na solution containing 0.05 mol / L of S 2 S 2 O 3 solution at a solid-liquid ratio of 1:12, transfer it to a reaction kettle, place it in an oven and carry out hydrothermal reaction at 150 °C for 20 h, then centrifuge at 2500 r / min for 6 min, wash repeatedly with deionized water, dry, grind, and sieve to obtain modified clay minerals.

[0046] Mix 85 parts of the above-mentioned modified clay minerals with 15 parts of humic acid evenly, place them in a ball mill and ball mill for 1.5 h to obtain a nickel stabilization agent.

[0047] Apply the above-mentioned nickel stabilization agent into the nickel-polluted soil after adjusting the pH value according to a mass ratio of 5%, and rototill and mix evenly.

[0048] S3: Adjust the water content and cover with film for maintenance

[0049] Adjust the water content of the nickel-polluted soil after rototilling and mixing to 60% of the maximum water holding capacity of the soil in the field, and cover with film for maintenance for 35 days.

[0050] After the curing is completed, soil samples are collected, air-dried naturally, ground and sieved, and the contents of various forms of nickel are analyzed and tested. The results are shown in Table 1.

[0051] S4: Crop planting

[0052] After the available nickel content reaches the expected target, cucumber planting is carried out, and a 100 mmol / L proline solution is sprayed 3 times at the early flowering stage of cucumbers.

[0053] After the cucumbers are mature, they are harvested, and the edible parts of the cucumbers are collected to determine their nickel content. The results are shown in Table 2.

[0054] Example 3

[0055] The method for safely utilizing nickel-contaminated soil in this example includes the following steps:

[0056] S1: Adjust the pH value

[0057] At least 40 days before planting crops, CaCO 3 The pH value of the nickel-contaminated soil is adjusted to between 7 and 7.5.

[0058] S2: Apply nickel stabilization agent

[0059] Kaolinite is dried, ground, and sieved, and then mixed evenly with a 0.5 mol / L sodium hydroxide solution at a solid-liquid ratio of 1:8, placed in a constant temperature oscillator and oscillated at 90 °C for 6 h, centrifuged at 3500 r / min for 4 min to separate sodium hydroxide and clay minerals, washed with deionized water, centrifuged and separated, and the washing and centrifugation are repeated 3 - 5 times until OH cannot be detected in the supernatant - until, the centrifuged kaolinite is dried, ground, and sieved to obtain alkali-modified clay minerals.

[0060] The alkali-modified clay minerals are mixed evenly with an Na 2 solution with an S content of 0.15 mol / L at a solid-liquid ratio of 1:8, transferred to a reaction kettle, placed in an oven and hydrothermally reacted at 180 °C for 12 h, then centrifuged at 3500 r / min for 4 min, repeatedly washed with deionized water, dried, ground, and sieved to obtain modified clay minerals.

[0061] 95 parts of the above-mentioned modified clay minerals are mixed evenly with 5 parts of humic acid, placed in a ball mill and ball milled for 2.5 h to obtain a nickel stabilization agent.

[0062] The above-mentioned nickel stabilization agent is applied to the nickel-contaminated soil with the pH value adjusted at a mass ratio of 2%, and rotary tillage is carried out to mix evenly.

[0063] S3: Adjust the water content, cover with film and cure

[0064] Adjust the water content of the nickel - contaminated soil after rotary tillage and mixing to 80% of the maximum water - holding capacity of the soil in the field, and cover it with a film for 25 days of curing.

[0065] After the curing is completed, collect soil samples, air - dry them naturally, grind them finely and sieve them, and analyze and test the contents of various forms of nickel. The results are shown in Table 1.

[0066] S4: Crop planting

[0067] After the available nickel content reaches the expected target, plant Chinese cabbages, and spray 200 mmol / L of proline solution twice during the rosette stage of Chinese cabbages.

[0068] After the Chinese cabbages are mature, harvest them, collect the edible parts of the Chinese cabbages and determine their nickel contents. The results are shown in Table 2.

[0069] Control Example 1

[0070] Except that in step S2, humic acid is not added, but instead the modified clay minerals are directly applied to the nickel - contaminated soil after adjusting the pH value at a mass ratio of 3.5%, the rest is the same as in Example 1.

[0071] Control Example 2

[0072] Except that in step S2, only alkali modification is used when preparing the modified clay minerals, the rest is the same as in Example 1; that is, the preparation method of the modified clay minerals in this control example is as follows:

[0073] Dry, grind and sieve kaolinite, then mix it evenly with 0.3 mol / L sodium hydroxide solution at a solid - liquid ratio of 1:10, place it in a constant - temperature oscillator and oscillate it at 80 °C for 7 h, centrifuge it at 3000 r / min for 5 min to separate sodium hydroxide and clay minerals, add deionized water to wash, centrifuge and separate, repeat the washing and centrifugation 3 - 5 times until OH cannot be detected in the supernatant - until, dry, grind and sieve the kaolinite after centrifugation and separation to obtain the modified clay minerals.

[0074] Control Example 3

[0075] Except that in step S2, only sulfur modification is used when preparing the modified clay minerals, the rest is the same as in Example 1; that is, the preparation method of the modified clay minerals in this control example is as follows:

[0076] Dry, grind and sieve kaolinite, then mix it evenly with Na2S2O4 solution with a sulfur content of 0.1 mol / L at a solid - liquid ratio of 1:10, transfer it to a reaction kettle, place it in an oven and carry out hydrothermal reaction at 165 °C for 16 h, then centrifuge it at 3000 r / min for 5 min, wash it repeatedly with deionized water, then dry, grind and sieve it to obtain the modified clay minerals.

[0077] Table 1 Contents of various forms of nickel in soil samples after maintenance for each example and control example

[0078]

[0079] Table 2 Nickel contents in edible parts of crops for each example and control example

[0080] Treatment Test crops Nickel in edible part (mg / kg) Example 1 Spinach 0.28 Example 2 Cucumber 0.29 Example 3 Chinese cabbage 0.43 Control Example 1 Spinach 0.88 Control Example 2 Spinach 0.93 Control Example 3 Spinach 0.82

[0081] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the examples of the present invention.

Claims

1. A method for safe utilization of nickel-contaminated soil, characterized in that: The steps include: S1: Add a pH adjuster to the nickel-contaminated soil at least 40 days before planting crops to adjust the pH value of the nickel-contaminated soil; S2: applying nickel stabilization agent to the nickel-contaminated soil after adjusting pH value, and rotary tilling and mixing; S3: adjusting the water content of the nickel-contaminated soil after rotary tillage and mixing, and covering with film for maintenance; S4: Planting crops after film covering and spraying nickel absorption inhibitor during crop planting; The pH regulator is selected from at least one of MgCO3 and CaCO3, and is used to adjust the pH value of the nickel-contaminated soil to 7-7.5; The nickel stabilizer is prepared by mixing modified clay mineral and humic acid and then ball milling. The mass ratio of the modified clay mineral to the humic acid in the nickel stabilizer is (8.5-9.5): (0.5-1.5). The ball milling time is 1.5-2.5 h. The modification methods of the modified clay mineral include alkali modification and sulfur modification. The alkali modification includes: drying, grinding and sieving the natural clay mineral, then mixing it with 0.125-0.5 mol / L sodium hydroxide solution at a solid-liquid ratio of 1: (8-12), shaking it at 70-90°C for 6-8 hours, centrifuging, washing, drying, grinding and sieving to obtain the alkali-modified clay mineral; the sulfur modification includes: mixing the alkali-modified clay mineral with a sulfur activator solution with a sulfur content of 0.05-0.15 mol / L at a solid-liquid ratio of 1: (8-12), then hydrothermally reacting it at 150-180°C for 12-20 hours, centrifuging, washing, drying, grinding and sieving to obtain the modified clay mineral; The nickel absorption inhibitor is a 100-200 mmol / L proline solution; the proline solution is sprayed 2-3 times.

2. The method for safe utilization of nickel-contaminated soil according to claim 1, characterized in that: Apply 2-5 kg ​​of nickel stabilization agent per 100 kg dry weight of topsoil.

3. The method for safe utilization of nickel-contaminated soil according to claim 1, characterized in that: The water content of the nickel-contaminated soil after rotary tillage and mixing was adjusted to 60-80% of the maximum field water holding capacity of the nickel-contaminated soil.

4. The method for safe utilization of nickel-contaminated soil according to claim 1, characterized in that: The film covering and curing time is 25-35 days.

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