A soil remediation material and its preparation method and application

Abstract

The present invention relates to the technical field of soil heavy metal pollution remediation, and specifically discloses a soil remediation material, its preparation method, and application. The raw materials of the soil remediation material provided by the present invention include 45 parts to 50 parts of modified magnesium aluminum hydrotalcite, 35 parts to 45 parts of mustard root, 5 parts to 8 parts of quicklime, 23 parts to 30 parts of bacterial solution, and 25 parts to 35 parts of water; wherein the modified magnesium aluminum hydrotalcite is sodium lauryl sulfate and ethylenediaminetetraacetic acid modified magnesium aluminum hydrotalcite; the bacterial solution is a mixed bacterial solution of Pseudomonas cepacia and Trametes spp. The soil remediation material developed based on modified magnesium aluminum hydrotalcite, mustard root, quicklime, Pseudomonas cepacia and Trametes spp., efficiently synergizes chemical remediation and microbial remediation technologies, and is particularly suitable for the treatment and remediation of heavy metal contaminated soil such as lead and cadmium in farmland, achieving efficient and long-lasting elimination of heavy metal pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of soil heavy metal pollution remediation, and in particular to a soil remediation material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of industry, the ecological environment is increasingly impacted by human production and daily life. Unlike the visible pollution of air, water, and solid waste, soil pollution is hidden and latent. Once contaminated, it is difficult to detect through sensory perception, resulting in the long-term accumulation of pollutants in the soil, which continuously harms the soil environment and the health of surrounding residents. Heavy metal pollution in soil is the long-term and irreversible accumulation of pollutants in the soil, making it difficult to remove through the self-purification capacity of the environment. Reportedly, the situation of heavy metal pollution in farmland soil is not optimistic. Heavy metal pollution in farmland soil not only affects the soil environment and arable land quality, but also seriously affects food safety and human health. Therefore, the remediation of heavy metal pollution in farmland soil has become a major environmental issue that needs to be addressed urgently.

[0003] Heavy metal pollution in farmland soil is mostly caused by sewage irrigation, industrial and mining enterprise pollution discharge, etc., and the main pollutants are heavy metals such as lead and cadmium. The existing remediation technologies are mainly physical remediation based on soil import and deep plowing, chemical remediation based on solidification / stabilization, and biological remediation based on plant remediation. Usually, a single remediation technology or a simple superposition of several remediation technologies is used to achieve the remediation and treatment of single-component or simple contaminated plots, but the remediation effect on multi-component complex contaminated plots is not good, and it is difficult to meet the needs of efficient remediation of farmland soil. In addition, the existing soil remediation materials also generally have the problem of short remediation control time, which makes it difficult to achieve the purpose of long-term remediation. Therefore, providing a soil remediation material that can remove multiple heavy metal pollutants at the same time and can achieve a long-term remediation effect is of great significance for the remediation of heavy metal-contaminated soil in farmland. Summary of the Invention

[0004] In view of this, the present invention provides a soil remediation material and its application. By selecting modified magnesium-aluminum hydrotalcite, mustard root, quicklime, and bacterial liquid of Pseudomonas cepacia and Trametes thunbergii as components of the soil remediation material, and determining the dosage of each component, the efficient and synergistic combination of chemical remediation and microbial remediation technology is promoted, the absorption and removal rate of heavy metal pollutants such as lead and cadmium is further improved, and efficient and long-lasting remediation of heavy metal contaminated soil is achieved.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A soil remediation material, the raw materials of which include the following components in parts by mass: 45-50 parts of modified magnesium-aluminum hydrotalcite, 35-45 parts of mustard root, 5-8 parts of quicklime, 23-30 parts of bacterial liquid and 25-35 parts of water;

[0007] The modified magnesium aluminum hydrotalcite is magnesium aluminum hydrotalcite modified by sodium lauryl sulfate and ethylenediaminetetraacetic acid; and the bacterial solution is a mixed bacterial solution of Pseudomonas cepacia and Trametes spp.

[0008] Compared with the prior art, the soil remediation material provided by the present invention uses two specific ingredients, sodium lauryl sulfate and ethylenediaminetetraacetic acid, to modify magnesium-aluminum hydrotalcite, so that sodium lauryl sulfate and ethylenediaminetetraacetic acid are intercalated into the magnesium-aluminum hydrotalcite, which can significantly improve the adsorption performance of the modified magnesium-aluminum hydrotalcite for heavy metal pollutants such as lead and cadmium in the soil. The inventors have demonstrated through numerous experiments that adding a specific amount of quicklime to the soil remediation material can adjust the soil pH and reaction temperature, allowing the modified magnesium-aluminum hydrotalcite to achieve an optimal adsorption state and effectively reduce the content of heavy metals such as lead and cadmium in the soil. When using chemical remediation methods, the inventors found that soil remediation materials with only modified magnesium-aluminum hydrotalcite as the main ingredient cannot achieve a lasting remediation effect. Based on the above problems, the inventors creatively added mustard roots and a mixed bacterial solution containing Pseudomonas cepacia and Trametes spp. into the soil remediation material system. Through the combined action of the two, the removal rate of lead in the soil by the soil remediation material can be significantly improved; quicklime also has a synergistic effect with the mustard roots and the mixed bacterial solution containing Pseudomonas cepacia and Trametes spp. in the present invention, while reducing the content of lead and cadmium in the soil, it can also improve the long-term removal rate of heavy metals in the soil; further, after a large number of experimental studies and explorations, the present invention screened modified magnesium-aluminum hydrotalcite, mustard roots, quicklime and a mixed bacterial solution containing Pseudomonas cepacia and Trametes spp. as components of the soil remediation material, and determined the dosage of each component, thereby promoting the efficient and synergistic use of chemical remediation and microbial remediation technologies, further improving the absorption and removal rate of heavy metal pollutants such as lead and cadmium, and realizing efficient and long-term remediation of heavy metal contaminated soil.

[0009] The ratio of the number of live bacteria of Pseudomonas cepacia to that of Trametes immitis in the bacterial solution is 2-3.5:1-2.2, and the total number of live bacteria in the bacterial solution is 1×10 5 -1×10 6 pieces / mL.

[0010] Preferably, the deposit number of the Pseudomonas cepacia is SHBCC D14769.

[0011] Preferably, the deposit number of the Trametes spp. is CICC 2671.

[0012] The present invention further defines the preservation numbers of Pseudomonas cepacia and Trametes spp. as well as the ratio of the number of live bacteria of Pseudomonas cepacia and Trametes spp. in the bacterial solution. Applying them to soil remediation materials can further improve the removal rate of the remediation materials for effective cadmium and effective lead in contaminated soil.

[0013] Preferably, the particle size of the modified magnesium-aluminum hydrotalcite is 100-130 mesh.

[0014] Preferably, the preparation method of the modified magnesium-aluminum hydrotalcite comprises the following steps:

[0015] Step a, adding magnesium nitrate and aluminum nitrate to water, adjusting the pH to 9.5-10.5, reacting at 110° C.-135° C., and filtering to obtain primary magnesium aluminum hydrotalcite;

[0016] Step b, calcining the primary magnesium-aluminum hydrotalcite at 550° C.-600° C. to obtain magnesium-aluminum hydrotalcite;

[0017] Step c, adding sodium lauryl sulfate, ethylenediaminetetraacetic acid and the magnesium aluminum hydrotalcite into water, adjusting the pH to 9-10, reacting at 85° C.-100° C., aging at 35° C.-40° C., washing, and drying to obtain the modified magnesium aluminum hydrotalcite.

[0018] The preferred modified magnesium-aluminum hydrotalcite is adjusted to a specific pH value and calcined at a specific temperature, which is beneficial for improving the dispersibility of the magnesium-aluminum hydrotalcite without destroying the structure of the primary magnesium-aluminum hydrotalcite. Furthermore, the specific pH and temperature conditions are conducive to the maximum intercalation of sodium lauryl sulfate and ethylenediaminetetraacetic acid into the magnesium-aluminum hydrotalcite. In step c, the aging temperature is further limited to improve the stability of the modified magnesium-aluminum hydrotalcite. The magnesium-aluminum hydrotalcite is modified by the specific modification method of the present invention and applied to soil remediation materials to greatly improve the removal rate of lead and cadmium in contaminated soil.

[0019] Preferably, in step a, the reaction time is 18-20 hours.

[0020] Preferably, in step a, the magnesium nitrate contains Mg 2+ With Al in aluminum nitrate 3+ The molar ratio is 2.3-2.5:1.

[0021] Preferably, in step a, the volume of water is 3-4 times the sum of the masses of magnesium nitrate and aluminum nitrate, the unit of volume is mL, and the unit of mass is g.

[0022] Preferably, in step b, the calcination time is 2.5h-3.5h.

[0023] Preferably, in step c, the reaction time is 10 h-12 h.

[0024] Preferably, in step c, the aging time is 1 h to 1.5 h.

[0025] Preferably, in step c, the mass ratio of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite is 3-3.2:1.5-2.2:1.

[0026] The preferred ratio is beneficial to the removal rate of heavy metals such as lead and cadmium in contaminated soil by the modified magnesium-aluminum hydrotalcite.

[0027] Preferably, in step c, the volume of water is 5-6 times the sum of the masses of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite, the unit of volume is mL, and the unit of mass is g.

[0028] The present invention provides a preparation method of the above-mentioned soil remediation material, which specifically comprises the following steps: weighing each component according to a mass ratio, adding the weighed modified magnesium-aluminum hydrotalcite and quicklime to water, and adding the mustard root and bacterial liquid at 20°C-25°C to obtain the soil remediation material.

[0029] The present invention also provides the use of the above-mentioned soil remediation material in heavy metal contaminated soil, wherein the heavy metal in the heavy metal contaminated soil is at least one of cadmium and lead.

[0030] Preferably, the amount of the soil remediation material is 65kg / mu-70kg / mu.

[0031] The soil remediation material provided by the present invention selects modified magnesium-aluminum hydrotalcite, mustard root, quicklime and a mixed bacterial solution containing Pseudomonas cepacia and Trametes thunbergii as components of the soil remediation material, and determines the dosage of each component, thereby promoting the efficient and synergistic use of chemical remediation and microbial remediation technologies. The material is applied to the remediation of farmland soil contaminated with lead and cadmium heavy metals, which can significantly reduce the content of lead and cadmium in the soil and effectively remove heavy metal elements in the soil. By adopting the efficient and synergistic use of chemical remediation and biological remediation technologies, the remediation efficiency and remediation durability of farmland soil contaminated with heavy metals can be effectively improved, thereby realizing the long-term and safe utilization of farmland soil. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] In order to better illustrate the present invention, further examples are given below.

[0034] Example 1

[0035] This embodiment provides a repair material, the raw materials of which include the following components by mass: 45 parts of modified magnesium-aluminum hydrotalcite with a particle size of 100 mesh, 45 parts of mustard root, 8 parts of quicklime, 23 parts of bacterial solution and 35 parts of water;

[0036] The preparation method of the modified magnesium-aluminum hydrotalcite comprises the following steps:

[0037] Step a, adding magnesium nitrate and aluminum nitrate into water, adjusting the pH to 9.5, reacting at 135°C for 20 hours, filtering, and obtaining primary magnesium aluminum hydrotalcite; the magnesium nitrate Mg 2+ With Al in aluminum nitrate 3+ The molar ratio is 2.3:1, the volume of water is 4 times the sum of the mass of magnesium nitrate and aluminum nitrate, the unit of volume is mL, and the unit of mass is g;

[0038] Step b, calcining the primary magnesium-aluminum hydrotalcite at 550° C. for 2.5 hours to obtain magnesium-aluminum hydrotalcite;

[0039] Step c, adding sodium lauryl sulfate, ethylenediaminetetraacetic acid and the magnesium aluminum hydrotalcite to water, adjusting the pH to 10, reacting at 100° C. for 10 hours, aging at 35° C. for 1 hour, washing, and drying to obtain the modified magnesium aluminum hydrotalcite; the mass ratio of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite is 3:2.2:1, the volume of water is 6 times the sum of the masses of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite, the unit of volume is mL, and the unit of mass is g;

[0040] The bacterial solution was 1×10 5 A mixed bacterial liquid of Pseudomonas cepacia and Trametes spp. at a concentration of 100 μg / mL, wherein the ratio of the number of live cells of Pseudomonas cepacia to that of Trametes spp. in the bacterial liquid is 2:1, the deposit number of Pseudomonas cepacia is SHBCC D14769, and the deposit number of Trametes spp. is CICC 2671.

[0041] Example 2

[0042] This embodiment provides a repair material, the raw materials of which include the following components in parts by mass: 50 parts of modified magnesium-aluminum hydrotalcite with a particle size of 130 mesh, 35 parts of mustard root, 5 parts of quicklime, 30 parts of bacterial solution and 25 parts of water;

[0043] The preparation method of the modified magnesium-aluminum hydrotalcite comprises the following steps:

[0044] Step a, adding magnesium nitrate and aluminum nitrate into water, adjusting the pH to 10.5, reacting at 110°C for 18 hours, filtering, and obtaining primary magnesium aluminum hydrotalcite; Mg in the magnesium nitrate 2+ With Al in aluminum nitrate 3+The molar ratio is 2.5:1, the volume of water is 3 times the sum of the mass of magnesium nitrate and aluminum nitrate, the unit of volume is mL, and the unit of mass is g;

[0045] Step b, calcining the primary magnesium-aluminum hydrotalcite at 600° C. for 3.5 hours to obtain magnesium-aluminum hydrotalcite;

[0046] Step c, adding sodium lauryl sulfate, ethylenediaminetetraacetic acid and the magnesium aluminum hydrotalcite to water, adjusting the pH to 9, reacting at 85° C. for 12 hours, aging at 40° C. for 1.5 hours, washing, and drying to obtain the modified magnesium aluminum hydrotalcite; the mass ratio of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite is 3.2:1.5:1, the volume of water is 5 times the sum of the masses of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite, the unit of volume is mL, and the unit of mass is g;

[0047] The bacterial solution was 1×10 6 A mixed bacterial liquid of Pseudomonas cepacia and Trametes spp. was prepared at a concentration of 100 μg / mL. The ratio of the number of live cells of Pseudomonas cepacia to that of Trametes spp. in the bacterial liquid was 3.5:2.2. The deposit number of Pseudomonas cepacia is SHBCC D14769, and the deposit number of Trametes spp. is CICC 2671.

[0048] Example 3

[0049] This embodiment provides a repair material, the raw materials of which include the following components in parts by mass: 48 parts of modified magnesium-aluminum hydrotalcite with a particle size of 120 mesh, 40 parts of mustard root, 6 parts of quicklime, 25 parts of bacterial solution and 25 parts of water;

[0050] The preparation method of the modified magnesium-aluminum hydrotalcite comprises the following steps:

[0051] Step a, adding magnesium nitrate and aluminum nitrate into water, adjusting the pH to 10, reacting at 120°C for 19h, filtering, and obtaining primary magnesium aluminum hydrotalcite; Mg in the magnesium nitrate 2+ With Al in aluminum nitrate 3+ The molar ratio is 2.4:1, the volume of water is 2.5 times the sum of the mass of magnesium nitrate and aluminum nitrate, the unit of volume is mL, and the unit of mass is g;

[0052] Step b, calcining the primary magnesium-aluminum hydrotalcite at 580° C. for 3 hours to obtain magnesium-aluminum hydrotalcite;

[0053] Step c, adding sodium lauryl sulfate, ethylenediaminetetraacetic acid and the magnesium aluminum hydrotalcite to water, adjusting the pH to 9.5, reacting at 90° C. for 11 hours, aging at 38° C. for 1.2 hours, washing, and drying to obtain the modified magnesium aluminum hydrotalcite; the mass ratio of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite is 3.1:2:1, the volume of water is 5.5 times the sum of the masses of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite, the unit of volume is mL, and the unit of mass is g;

[0054] The bacterial solution was 1×10 5 A mixed bacterial liquid of Pseudomonas cepacia and Trametes spp. at a concentration of 100 μg / mL was prepared, wherein the ratio of the number of live cells of Pseudomonas cepacia to that of Trametes spp. in the bacterial liquid was 3:2. The deposit number of Pseudomonas cepacia is SHBCC D14769, and the deposit number of Trametes spp. is CICC 2671.

[0055] Comparative Example 1

[0056] Compared with Example 1, the difference between this comparative example and Example 1 is that the mustard roots are replaced with an equal amount of cabbage roots, and the other operating steps are the same as those in Example 1.

[0057] Comparative Example 2

[0058] Compared with Example 1, the difference between this comparative example and Example 1 is that sodium lauryl sulfate is replaced by an equal amount of sodium lauryl sulfate, and the other operating steps are the same as those in Example 1.

[0059] Comparative Example 3

[0060] Compared with Example 1, the difference between this comparative example and Example 1 is that Pseudomonas cepaciae is replaced by an equal amount of Bacillus cereus, and the other operating steps are the same as those in Example 1.

[0061] Comparative Example 4

[0062] Compared with Example 1, the difference between this comparative example and Example 1 is that the amount of modified magnesium-aluminum hydrotalcite is increased to 58 parts, and the other operating steps are the same as those in Example 1.

[0063] Comparative Example 5

[0064] Compared with Example 1, the difference between this comparative example and Example 1 is that the number of portions of the bacterial solution is changed to 42 portions, and the other operating steps are the same as those in Example 1.

[0065] Application Examples

[0066] Six contaminated soils with comparable cadmium and lead contents were selected for testing to measure the contents of available lead and available cadmium in the contaminated soils. First, the soil was plowed to a depth of 20 cm, and the soil remediation materials of Examples 1-3 and Comparative Examples 1-3 were added in an amount of 70 kg / mu. After stabilization for 15 days, soil samples were obtained using a five-point sampling method. After drying in a cool and ventilated place, the soil was sieved through a 20-mesh sieve to determine the contents of available cadmium and available lead in the soil. The available cadmium and available lead in the soil were determined using the "Soil Quality - Determination of Available Lead and Cadmium - Atomic Absorption Method" (GB / T23739 2009) detection method, and the specific test results are shown in the following table:

[0067] Table 1

[0068]

[0069] The soil remediation materials prepared by Examples 1-3 of the present invention can simultaneously remove the contents of available cadmium and available lead in contaminated soil, with a removal rate of more than 90%, and can also achieve a lasting remediation effect.

[0070] The soil remediation material provided herein screens modified magnesium-aluminum hydrotalcite, mustard root, quicklime, and a mixed bacterial solution containing Pseudomonas cepacia and Trametes thunbergii as components of the soil remediation material, and determines the dosage of each component, thereby promoting the efficient and synergistic use of chemical remediation and microbial remediation technologies. When applied to the remediation of farmland soil contaminated with lead and cadmium heavy metals, the content of lead and cadmium in the soil can be significantly reduced, and the heavy metal elements in the soil can be effectively removed. By adopting the efficient and synergistic use of chemical remediation and biological remediation technologies, the remediation efficiency and remediation durability of farmland heavy metal contaminated soil can be effectively improved, thereby achieving long-term and safe utilization of farmland soil.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soil remediation material, characterized in that: The raw materials include the following components in parts by mass: 45-50 parts of modified magnesium-aluminum hydrotalcite, 35-45 parts of mustard root, 5-8 parts of quicklime, 23-30 parts of bacterial liquid and 25-35 parts of water; Wherein, the modified magnesium aluminum hydrotalcite is magnesium aluminum hydrotalcite modified by sodium lauryl sulfate and ethylenediaminetetraacetic acid; the bacterial solution is a mixed bacterial solution of Pseudomonas cepacia and Trametes spp.; The particle size of the modified magnesium-aluminum hydrotalcite is 100-130 meshes.

2. The soil remediation material according to claim 1, characterized in that: The ratio of the number of live bacteria of Pseudomonas cepacia to that of Trametes immitis in the bacterial solution is 2-3.5:1-2.2, and the total number of live bacteria in the bacterial solution is 1×10 5 -1×10 6 pieces / mL.

3. The soil remediation material according to claim 1, wherein The deposit number of the Pseudomonas cepacia is SHBCC D14769; and / or The deposit number of the Trametes thunbergii is CICC 2671.

4. The soil remediation material according to claim 1, wherein The preparation method of the modified magnesium-aluminum hydrotalcite comprises the following steps: Step a, adding magnesium nitrate and aluminum nitrate to water, adjusting the pH to 9.5-10.5, reacting at 110° C.-135° C., and filtering to obtain primary magnesium aluminum hydrotalcite; Step b, calcining the primary magnesium-aluminum hydrotalcite at 550° C.-600° C. to obtain magnesium-aluminum hydrotalcite; Step c, adding sodium lauryl sulfate, ethylenediaminetetraacetic acid and the magnesium aluminum hydrotalcite into water, adjusting the pH to 9-10, reacting at 85° C.-100° C., aging at 35° C.-40° C., washing, and drying to obtain the modified magnesium aluminum hydrotalcite.

5. The soil remediation material according to claim 4, characterized in that: In step a, the reaction time is 18-20h; and / or In step a, Mg in the magnesium nitrate 2+ With Al in aluminum nitrate 3+ The molar ratio is 2.3-2.5:1; and / or In step a, the volume of the water is 3-4 times the sum of the masses of magnesium nitrate and aluminum nitrate, the unit of volume is mL, and the unit of mass is g.

6. The soil remediation material according to claim 4, characterized in that: In step b, the calcination time is 2.5h-3.5h.

7. The soil remediation material according to claim 4, characterized in that: In step c, the mass ratio of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite is 3-3.2:1.5-2.2:1; and / or In step c, the volume of water is 5-6 times the sum of the mass of sodium lauryl sulfate, ethylenediaminetetraacetic acid and magnesium aluminum hydrotalcite, the unit of volume is mL, and the unit of mass is g; and / or In step c, the reaction time is 10h-12h; and / or In step c, the aging time is 1 h to 1.5 h.

8. Use of the soil remediation material according to any one of claims 1 to 7 in heavy metal contaminated soil, characterized in that: The heavy metal in the heavy metal contaminated soil is at least one of cadmium and lead.

9. Use of the soil remediation material according to claim 8 in heavy metal contaminated soil, characterized in that: The amount of the soil remediation material used is 65kg / mu-70kg / mu.

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