Soil remediation method based on iron-based nano material and plants

Abstract

The invention relates to a soil remediation method based on an iron-based nano material and plants, the iron-based nano material comprises MIL-88A (Fe) and / or MIF-101 (Fe), the plants comprise ramie, and a plant root system is combined with the iron-based nano material to carry out combined remediation on heavy metal contaminated soil; wherein the iron-based nano material is used for carrying out in-situ chemical stabilization on heavy metals in soil, the plants are used for carrying out plant stabilization on the heavy metals in the soil, and the iron-based nano material and the plants are combined for chemical remediation and plant remediation to fix the heavy metals in the polluted soil at plant rhizosphere; according to the method, toxicity of arsenic to ramie is reduced by fixing arsenic, and ramie rhizosphere microflora is adjusted to promote growth of ramie; ramie can also play a role in fixing arsenic by plants, arsenic in the arsenic-polluted soil is converted into stable residual arsenic by combining with the remediation material, toxic leaching and bioavailability of arsenic are reduced, the risk of arsenic accumulation of crops is reduced, and the biomass and quality of crops are improved.

Description

Technical Field

[0001] The present invention relates to the field of soil heavy metal pollution remediation, and in particular to a soil remediation method based on iron-based nanomaterials and plants. Background Art

[0002] Arsenic is a metalloid element that exists naturally in the earth's crust, soil, water, atmosphere and organisms. It is identified as a Class 1 human carcinogen by the International Agency for Research on Cancer. Soil arsenic contamination is hidden, long-term and irreversible, and can spread to various biota through the food chain, posing a threat to all trophic levels. Therefore, the problem of soil arsenic contamination must be addressed to ensure human safety and promote sustainable development.

[0003] In the existing technology, the technology of repairing soil arsenic contamination is mainly classified into physical remediation (soil replacement method, imported soil method, deep tillage method, electric remediation method), chemical remediation (elution method, solidification / stabilization method), and biological remediation (plant remediation, microbial remediation). Among them, chemical stabilization remediation technology has the advantages of wide application range, little damage to soil environment, simple operation, and economic saving; while plant remediation technology has the advantages of low cost, strong environmental sustainability, high landscape value, and little interference with soil structure.

[0004] Therefore, a soil remediation method based on iron-based nanomaterials and plants is provided, which combines chemical remediation and phytoremediation to efficiently remediate soil heavy metal pollution, especially soil arsenic pollution. Summary of the invention

[0005] In response to the problem of heavy metal pollution in soil in the prior art, the present invention provides a soil remediation method based on iron-based nanomaterials and plants that combines chemical remediation and phytoremediation to efficiently remediate heavy metal pollution in soil, especially arsenic pollution in soil.

[0006] The present invention provides a soil remediation method based on iron-based nanomaterials and plants, wherein the iron-based nanomaterials include MIL-88A (Fe) and / or MIF-101 (Fe), the plants include ramie, and the plant root system and the iron-based nanomaterials are combined to perform joint remediation of heavy metal-contaminated soil; wherein the iron-based nanomaterials perform in-situ chemical stabilization of heavy metals in the soil, and the plants perform plant stabilization of the heavy metals in the soil, and the two are combined to perform chemical remediation and plant remediation to fix the heavy metals in the contaminated soil in the plant rhizosphere.

[0007] The steps include: S1. After the target soil is fully turned over, the iron-based nanomaterials are added and mixed evenly with the target soil; S2. Transplant the whole plant seedlings into the target soil treated in S1 and continue planting for at least 45 days.

[0008] In S1, the target soil needs to be pretreated before restoration, and the pretreatment includes natural air drying, grinding and removal of animal and plant residues.

[0009] In S2, the content of iron-based nanomaterials in the target soil was 0.1%-0.5% before the plant seedlings were transplanted.

[0010] Requirements for continuous planting include daytime temperatures of 28-33°C, nighttime temperatures of 18-23°C, soil moisture content stabilized at 60% of the maximum field capacity, and continuous planting time of no less than 45 days.

[0011] The target soil is arsenic-contaminated soil; during remediation, the TCLP procedure is used to detect arsenic leaching in the remediated arsenic-contaminated soil, and the improved Wenzel extraction method is used to detect changes in the arsenic form distribution in the remediated arsenic-contaminated soil.

[0012] The technical solution of the present invention has the following advantages: Compared with the chemical remediation of simply adding iron-based nanomaterials, the soil remediation method based on iron-based nanomaterials and plants described in the present invention strengthens the fixation effect of iron-based nanomaterials on soil arsenic in the root zone of plants, greatly increasing the level of residual arsenic in rhizosphere soil; iron-based nanomaterials effectively fix soil arsenic, significantly reduce the toxicity of arsenic to plants, promote plant growth, and strengthen plant remediation; that is, iron-based nanomaterials and plants complement each other, greatly reduce the biological effectiveness of arsenic in arsenic-contaminated soil, fix soil biologically available arsenic and convert it into stable residual arsenic, reduce the arsenic content of crops, and contribute to soil health and food safety. Moreover, compared with other soil remediation methods, such as soil replacement method, soil removal method, electric remediation method, heat treatment method, chemical leaching method, microbial remediation, etc., this method is simple to operate, low in cost, stable in effect, environmentally friendly, less physically damaging to the soil, does not cause secondary pollution, and also adds a certain landscape value; this method has strong adaptability and practicality, and has a good application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are an application method of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0014] Figure 1 This is an analysis of the fixation effects of two iron-based nanomaterials on soil arsenic on the 45th day; Figure 2 This is an analysis of the fixation effects of two iron-based nanomaterials on soil arsenic at day 90; Figure 3 Analysis of the arsenic fixation effect of combining iron-based nanomaterials with ramie to repair arsenic-contaminated soil on the 45th day; Figure 4 To study the changes of growth physiological indexes of ramie under arsenic stress and two iron-based nanomaterials treatments; Figure 5 The effects of two iron-based nanomaterials on the absorption, transport and enrichment of soil arsenic by ramie. DETAILED DESCRIPTION

[0015] In order to further explain the purpose, technical solutions and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention are described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all. Based on these embodiments in the present invention, all other embodiments obtained without creative work are within the scope of protection of the present invention.

[0016] The present invention discloses a soil remediation method based on iron-based nanomaterials and plants, wherein the iron-based nanomaterials include MIL-88A (Fe) and / or MIF-101 (Fe), the plants include ramie, and the plant roots are combined with the iron-based nanomaterials to perform joint remediation on soil contaminated by heavy metals; wherein the iron-based nanomaterials perform in-situ chemical stabilization on the heavy metals in the soil, and the plants perform plant stabilization on the heavy metals in the soil, and the two are combined to perform chemical remediation and plant remediation to fix the heavy metals in the contaminated soil in the plant rhizosphere.

[0017] Specifically, the method comprises the following steps: S1. After the target soil is fully turned over, add the iron-based nanomaterials and the target soil and mix them evenly. Weigh 3 kg of the treated soil and add it to a flower pot with a diameter of 15 cm and a height of 20 cm.

[0018] In S1, the target soil needs to be pretreated before restoration, and the pretreatment includes natural air drying, grinding and removal of animal and plant residues.

[0019] S2. Transplant the whole plant seedlings into the target soil treated in S1, transplant one ramie seedling per pot, and continue planting for at least 45 days.

[0020] In S2, the content of iron-based nanomaterials in the target soil was 0.1%-0.5% before the plant seedlings were transplanted.

[0021] Requirements for continuous planting include daytime temperatures of 28-33°C, nighttime temperatures of 18-23°C, soil moisture content stabilized at 60% of the maximum field capacity, and continuous planting time of no less than 45 days.

[0022] In this embodiment, the target soil is preferably arsenic-contaminated soil; during remediation, the TCLP procedure is used to detect arsenic leaching in the remediated arsenic-contaminated soil, and the improved Wenzel extraction method is used to detect changes in the arsenic form distribution in the remediated arsenic-contaminated soil.

[0023] Specifically, in this embodiment, The addition ratio of iron-based nanomaterials to the combined restoration of heavy metal arsenic contaminated soil using iron-based nanomaterials coupled with ramie ranges from 0.1% to 0.5%.

[0024] Furthermore, after 45 days of joint restoration, 0.1%-0.5% MIL-88A(Fe) or MIF-101(Fe) combined with ramie reduced the arsenic toxicity leaching in the rhizosphere soil by 31.8%-63.0% and increased the percentage of residual arsenic in the rhizosphere soil by 5-10%. Compared with the effect of iron-based nanomaterials alone: ​​after 45 days of restoration, 0.1%-0.5% MIL-88A(Fe) or MIF-101(Fe) reduced the arsenic toxicity leaching in the soil by 9.5%-50.8% and increased the percentage of residual arsenic in the rhizosphere soil by 2-6%; after 90 days of restoration, 0.1%-0.5% MIL-88A(Fe) or MIF-101(Fe) reduced the arsenic toxicity leaching in the soil by 12.8%-55.5% and increased the percentage of residual arsenic in the rhizosphere soil by 4-7%. This shows that compared with the simple iron-based nanomaterial remediation method, this combined remediation method has better arsenic fixation performance.

[0025] Furthermore, after 45 days of combined restoration, 0.1%-0.5% MIL-88A(Fe) or MIF-101(Fe) treatment reduced arsenic content in ramie roots by 41.8%-70.2%, arsenic content in stems by 17.9%-44.6%, arsenic content in leaves by 15.5%-39.7%, and reduced arsenic bioaccumulation coefficient in ramie by 37.0%-61.7%, indicating that arsenic was fixed in rhizosphere soil and arsenic bioavailability was greatly reduced.

[0026] Furthermore, after 45 days of joint restoration, 0.1%-0.5% MIL-88A (Fe) or MIF-101 (Fe) treatment increased ramie root dry weight by 11.3%-27.0%; ramie stem and leaf dry weight by 9.8%-27.8; ramie plant height by 5.9%-16.1%; ramie maximum leaf width by 27.7%-32.5%; reduced ramie leaf MDA by 23.1%-50.5%; reduced ramie leaf SOD by 51.9%-78.8%. This indicates that iron-based nanomaterials can reduce arsenic oxidative damage to ramie, reduce arsenic toxicity to ramie, and promote ramie growth.

[0027] The method and its effects described in the present application will be described in detail below using specific examples and comparative examples.

[0028] Comparative Example 1: This comparative example is a basic comparative example, that is, no repair material is added.

[0029] Specifically, farmland soil was collected in XX city, XX province, China. With reference to China's soil risk control standards for agricultural land (GB15618-2018), the farmland soil was contaminated and stabilized with sodium arsenite, resulting in the arsenic content in the farmland soil seriously exceeding the standard, with a total arsenic content of 120 mg / kg (risk screening value is 25 mg / kg).

[0030] The steps of this comparative example are as follows: Pretreatment: The arsenic-contaminated soil used in the test is naturally air-dried, ground, and freed of animal and plant debris.

[0031] Remediation treatment: No remediation materials were added to the pre-treated arsenic-contaminated soil, only ultrapure water was added, and the soil was numbered CK. During the remediation process, the soil moisture content was maintained at 60% of the maximum field water holding capacity, and the culture conditions were 28-33°C during the day and 18-23°C at night. Soil samples were taken on the 45th and 90th days.

[0032] Comparative Example 2: In this comparative example, iron-based nanomaterials were added alone to repair arsenic-contaminated soil for testing.

[0033] Specifically, farmland soil was collected in XX city, XX province, China. With reference to China's soil risk control standards for agricultural land (GB15618-2018), the farmland soil was contaminated and stabilized with sodium arsenite, resulting in soil arsenic content seriously exceeding the standard, with a total arsenic content of 120 mg / kg (risk screening value is 25 mg / kg).

[0034] The steps of using iron-based nanomaterials alone to repair arsenic-contaminated soil in this embodiment are as follows: Pretreatment: The arsenic-contaminated soil used in the test is naturally air-dried, ground, and freed of animal and plant debris.

[0035] Mixing treatment: Mix MIL-88A(Fe) and the pretreated heavy metal arsenic contaminated soil and stir them evenly. The addition amount of MIL-88A(Fe) is 0.1%-0.5% of the soil mass.

[0036] Remediation treatment: Ultrapure water was regularly added to the soil to which MIL-88A(Fe) was added. During the remediation process, the soil moisture content was maintained at 60% of the maximum field water holding capacity. The culture conditions were 28-33°C during the day and 18-23°C at night. Soil samples were taken on the 45th and 90th days.

[0037] Comparative Example 3: In this comparative example, iron-based nanomaterials were added alone to repair arsenic-contaminated soil for testing.

[0038] Farmland soil was collected in XX city, XX province, China. With reference to China's soil risk management standard for agricultural land (GB 15618-2018), the farmland soil was contaminated and stabilized with sodium arsenite, resulting in a serious excess of arsenic in the soil, with a total arsenic content of 120 mg / kg (risk screening value is 25 mg / kg).

[0039] The steps of using iron-based nanomaterials alone to repair arsenic-contaminated soil in this embodiment are as follows: Pretreatment: The arsenic-contaminated soil used in the test is naturally air-dried, ground, and freed of animal and plant debris.

[0040] Mixing treatment: Mix MIF-101(Fe) and the pretreated heavy metal arsenic contaminated soil and stir them evenly. The dosage of MIF-101(Fe) is 0.1%-0.5% of the soil mass.

[0041] Remediation treatment: Ultrapure water was regularly added to the soil to which MIF-101(Fe) was added. During the remediation process, the soil moisture content was maintained at 60% of the maximum field water holding capacity. The culture conditions were 28-33°C during the day and 18-23°C at night. Soil samples were taken on the 45th and 90th days.

[0042] Comparative Example 4: In this comparative example, ramie was planted alone to repair arsenic-contaminated soil for testing.

[0043] The soil was collected in XX city, XX province, China. With reference to China's soil risk management standard for agricultural land (GB 15618-2018), the soil was contaminated and stabilized with sodium arsenite, resulting in a serious excess of arsenic in the soil, with a total arsenic content of 120 mg / kg (the risk screening value is 25 mg / kg).

[0044] The steps of this comparative example are as follows: Pretreatment: The arsenic-contaminated soil used for combined remediation was naturally air-dried, ground, and the animal and plant remains were removed. 3 kg of the treated soil was weighed and added to a flower pot with a diameter of 15 cm and a height of 20 cm.

[0045] Remediation treatment: The combined remediation heavy metal arsenic contaminated soil was planted with ramie seedlings without adding remediation materials. One ramie seedling was transplanted into each pot and numbered RCK. Ultrapure water was applied regularly to maintain the soil moisture content at 60% of the maximum field water holding capacity. The planting temperature was: 28-33°C during the day and 18-23°C at night. Ramie and rhizosphere soil were sampled and analyzed 45 days after the combined remediation.

[0046] Example 1: In this example, ramie and iron-based nanomaterials are combined to repair arsenic-contaminated soil, and a 0.1%-0.5% dosage of the material is coupled with ramie for joint repair.

[0047] The soil was collected in XX city, XX province, China. With reference to China's soil risk management standard for agricultural land (GB 15618-2018), the soil was contaminated and stabilized with sodium arsenite, resulting in a serious excess of arsenic in the soil, with a total arsenic content of 120 mg / kg (the risk screening value is 25 mg / kg).

[0048] The steps of combining ramie with iron-based nanomaterials to repair arsenic-contaminated soil in this embodiment are as follows: Pretreatment: The arsenic-contaminated soil used in the combined remediation process is naturally air-dried, ground, and freed of plant and animal debris.

[0049] Mixing treatment: Mix MIL-88A(Fe) and arsenic-contaminated soil evenly. The dosage of MIL-88A(Fe) is 0.1%-0.5% of the soil mass. Weigh 3kg of treated soil and add it to a flowerpot with a diameter of 15cm and a height of 20cm.

[0050] Remediation treatment: Ramie seedlings were transplanted into arsenic-contaminated soil with MIL-88A(Fe), with one ramie seedling transplanted per pot, and ultrapure water was applied regularly to maintain soil moisture at 60% of the maximum field water holding capacity. Planting temperature was: 28-33°C during the day and 18-23°C at night. Ramie and rhizosphere soil were sampled and analyzed 45 days after the combined remediation.

[0051] Example 2: In this example, ramie and iron-based nanomaterials are combined to repair arsenic-contaminated soil, and a dosage of 0.1%-0.5% of the material is coupled with ramie for joint repair.

[0052] The soil was collected in XX city, XX province, China. With reference to China's soil risk management standard for agricultural land (GB 15618-2018), the soil was contaminated and stabilized with sodium arsenite, resulting in a serious excess of arsenic in the soil, with a total arsenic content of 120 mg / kg (the risk screening value is 25 mg / kg).

[0053] The steps of combining ramie with iron-based nanomaterials to repair arsenic-contaminated soil in this embodiment are as follows: Pretreatment: The arsenic-contaminated soil used in the combined remediation process is naturally air-dried, ground, and freed of plant and animal debris.

[0054] Mixing treatment: Mix MIF-101(Fe) and arsenic-contaminated soil evenly. The dosage of MIF-101(Fe) is 0.1%-0.5% of the soil mass. Weigh 3kg of treated soil and add it to a flowerpot with a diameter of 15cm and a height of 20cm.

[0055] Remediation treatment: Ramie seedlings were transplanted into arsenic-contaminated soil with MIF-101(Fe) added. One ramie seedling was transplanted into each pot, and ultrapure water was applied regularly to maintain the soil moisture content at 60% of the maximum field water holding capacity. The planting temperature was: 28-33°C during the day and 18-23°C at night. Ramie and rhizosphere soil were sampled and analyzed 45 days after the combined remediation.

[0056] The treatments in Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were all repeated 5 times.

[0057] Result detection and analysis 1. Analysis of soil physical and chemical properties The changes in the physical and chemical properties of the soil in Examples 1 and 2 and Comparative Examples 1, 2, 3, and 4 are shown in the following table.

[0058] Table 1. Changes in soil enzyme activities after 45 days of restoration in Examples 1, 2 and Comparative Examples 1, 2, 3, and 4 Note: The data in the table are mean ± standard deviation, and different letters represent significant differences ( p <0.05)

[0059] Although the difference in soil catalase activity between Examples 1 and 2 and the comparative example is small, the soil catalase activity of Examples 1 and 2 is improved compared with that of Comparative Example 4, which indicates that the addition of iron-based nanomaterials has a promoting effect on the catalase activity in arsenic-contaminated soil. Compared with Comparative Example 1, Example 1 is compared with Comparative Example 2; and Example 2 is compared with Comparative Example 3, the soil catalase activity is also improved, indicating that ramie planting further promotes soil catalase activity under the condition of adding iron-based nanomaterials.

[0060] There are differences in soil urease activity between Examples 1 and 2 and Comparative Examples 1, 2, 3, and 4. The soil urease activity of Examples 1 and 2 is significantly improved compared to Comparative Example 4, which shows that the addition of iron-based nanomaterials significantly increases the urease activity in arsenic-contaminated soil, and compared with Comparative Example 2 in Example 1; compared with Comparative Example 3 in Example 2, the soil urease activity is also improved, indicating that ramie planting further increases soil urease activity on the basis of adding iron-based nanomaterials.

[0061] In summary, after 45 days of combined iron-based nanomaterials and ramie remediation of arsenic-contaminated soil, the soil catalase activity and urease activity were improved, and compared with the application of iron-based nanomaterials alone, the combined remediation soil enzyme activity was higher, indicating that compared with the remediation of iron-based nanomaterials alone, the combined remediation method can better improve the physical and chemical properties of the soil.

[0062] 2. Analysis of Arsenic Leaching from Soil The available arsenic content in the soil was extracted according to the TCLP procedure, and the changes in the soil arsenic leaching level during the remediation process of each case were determined.

[0063] Compared with comparative example 1, using only iron-based nanomaterials, after 45 days of restoration, 0.1%-0.5% MIL-88A (Fe) in comparative example 2 reduced the soil arsenic leaching level by 12.6%-50.8%, and 0.1%-0.5% MIF-101 (Fe) in comparative example 3 reduced the soil arsenic leaching level by 9.5%-44.4%; Figure 1 shown.

[0064] Compared with comparative example 1, using only iron-based nanomaterials, after 90 days of restoration, 0.1%-0.5% MIL-88A (Fe) in comparative example 2 reduced the soil arsenic leaching level by 15.7%-55.5%, and 0.1%-0.5% MIF-101 (Fe) in comparative example 3 reduced the soil arsenic leaching level by 12.8%-52.2%. Figure 2 shown.

[0065] Compared with Comparative Example 4, after 45 days of combined remediation, the ramie combined with 0.1%-0.5% MIL-88A (Fe) in Example 1 reduced the soil arsenic leaching level by 34.4%-63.0%, and the ramie combined with 0.1%-0.5% MIF-101 (Fe) in Example 2 reduced the soil arsenic leaching level by 31.8%-60.7%. Figure 3 shown.

[0066] Compared with Example 1, the arsenic leaching level of the soil without repair materials in Example 4 at 45 days was lower than that of the iron-based nanomaterials alone at 45 days and 90 days, indicating that ramie also has a certain arsenic fixation effect.

[0067] On the 45th day, the application of iron-based nanomaterials alone reduced the arsenic leaching level in the soil by 9.5%-50.8%; on the 90th day, the application of iron-based nanomaterials alone reduced the arsenic leaching level in the soil by 12.8%-55.5%; on the 45th day, the combination of ramie and iron-based nanomaterials reduced the arsenic leaching level in the soil by 31.8%-63.0%. Combined remediation reduced soil arsenic leaching to a greater extent.

[0068] In summary, the two iron-based nanomaterials successfully fixed soil arsenic, and the remediation method combining ramie and iron-based nanomaterials was superior in the performance of fixing soil arsenic.

[0069] 3. Soil arsenic speciation analysis The modified Wenzel extraction method was used to determine the changes in the distribution of arsenic forms in the remediated soil.

[0070] Compared with comparative example 1, after 45 days of restoration, the 0.1%-0.5% MIL-88A (Fe) in comparative example 2 increased the residual arsenic level in the soil by 3-6 percentage points, and the 0.1%-0.5% MIF-101 (Fe) in comparative example 3 increased the residual arsenic level in the soil by 2-4 percentage points ( Figure 1 ).

[0071] Compared with comparative example 1, when iron-based nanomaterials were used alone, after 90 days of restoration, 0.1%-0.5% MIL-88A (Fe) in comparative example 2 increased the residual arsenic level in the soil by 5-7 percentage points, and 0.1%-0.5% MIF-101 (Fe) in comparative example 3 increased the residual arsenic level in the soil by 4-6 percentage points ( Figure 2 ).

[0072] Compared with comparative example 4, after 45 days of combined remediation, the ramie combined with 0.1%-0.5% MIL-88A (Fe) in Example 1 increased the residual arsenic level in the soil by 6-10 percentage points, and the ramie combined with 0.1%-0.5% MIF-101 (Fe) in Example 2 increased the residual arsenic level in the soil by 5-9 percentage points ( Figure 3 ).

[0073] On the 45th day, the application of iron-based nanomaterials alone increased the residual arsenic level in the soil by 2-6 percentage points; on the 90th day, the application of iron-based nanomaterials alone increased the residual arsenic level in the soil by 4-7 percentage points; on the 45th day, the combination of ramie and iron-based nanomaterials increased the residual arsenic level in the soil by 5-10 percentage points. The percentage of soil arsenic converted to residual arsenic by combined remediation is higher.

[0074] In summary, the two iron-based nanomaterials successfully fixed soil arsenic, and the remediation method combining ramie and iron-based nanomaterials was more effective in fixing soil arsenic and converting it into residual arsenic.

[0075] 4. Analysis of Ramie Growth Index The root dry weight, aboveground part (stem and leaf) dry weight, maximum leaf width, plant height, leaf malondialdehyde (MDA) and superoxide dismutase (SOD) contents of ramie were measured on the 45th day after the combined restoration. Figure 4 shown.

[0076] Compared with Comparative Example 4, the addition of iron-based nanomaterials in Example 1 and Example 2 increased the dry weight of ramie roots by 11.3%-27.0%; the dry weight of ramie stems and leaves by 9.8%-27.8; the ramie plant height by 5.9%-16.1%; the maximum leaf width of ramie by 27.7%-32.5%; reduced the MDA of ramie leaves by 23.1%-50.5%; and reduced the SOD of ramie leaves by 51.9%-78.8%.

[0077] This shows that in arsenic-contaminated soil, iron-based nanomaterials reduce the oxidative damage of arsenic to ramie and promote the growth of ramie.

[0078] 5. Analysis of arsenic enrichment in ramie After 45 days of joint restoration, the ramie harvested and sampled were divided into three parts: roots, stems, and leaves. After the roots were washed with ultrapure water, the root, stem, and leaf samples were placed in an oven for sterilization. An appropriate amount of sterilized samples were taken and digested with nitric acid, hydrofluoric acid, and hydrogen peroxide. The arsenic content in the samples was determined using ICP-MS, and the arsenic bioaccumulation coefficient was calculated.

[0079] Arsenic bioaccumulation coefficient = arsenic content in ramie / arsenic content in soil.

[0080] like Figure 5 As shown, compared with Comparative Example 4, the addition of iron-based nanomaterials in Examples 1 and 2 reduced the arsenic content in ramie roots by 41.8%-70.2%, the arsenic content in stems by 17.9%-44.6%, the arsenic content in leaves by 15.5%-39.7%, and reduced the bioaccumulation coefficient of arsenic in ramie by 37.0%-61.7%.

[0081] The arsenic content and arsenic bioaccumulation coefficient in ramie were significantly reduced, indicating that the combined restoration successfully fixed arsenic in the soil and reduced the bioavailability of arsenic.

[0082] In summary, compared with the chemical remediation of simply adding iron-based nanomaterials, the root zone of the plant strengthens the fixation effect of iron-based nanomaterials on soil arsenic, greatly increasing the level of residual arsenic in the rhizosphere soil; the iron-based nanomaterials effectively fix the soil arsenic, significantly reducing the toxicity of arsenic to plants, promoting plant growth, and strengthening plant remediation; that is, the iron-based nanomaterials and plants complement each other, greatly reducing the biological effectiveness of arsenic in arsenic-contaminated soil, fixing the soil biologically available arsenic and converting it into stable residual arsenic, reducing the arsenic content of crops, and contributing to soil health and food safety. Moreover, compared with other soil remediation methods, such as soil replacement method, soil removal method, electric remediation method, heat treatment method, chemical leaching method, microbial remediation, etc., this method is simple to operate, low in cost, stable in effect, environmentally friendly, little physical damage to the soil, no secondary pollution, and also adds a certain landscape value; this method has strong adaptability and practicality, and has a good application and promotion value.

[0083] Obviously, the above is the preferred implementation of the present application, but it should not be understood as limiting the scope of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A soil remediation method based on iron-based nanomaterials and plants, characterized in that: The iron-based nanomaterials include MIL-88A (Fe) and / or MIF-101 (Fe), the plants include ramie, and the plant roots are combined with the iron-based nanomaterials to perform joint repair of soil contaminated by heavy metals; wherein, the iron-based nanomaterials perform in-situ chemical stabilization of heavy metals in the soil, and the plants perform plant stabilization of the heavy metals in the soil, and the combined chemical repair and plant repair of the two fix the heavy metals in the contaminated soil in the plant rhizosphere.

2. The soil remediation method based on iron-based nanomaterials and plants according to claim 1, characterized in that: The steps include: S1. After the target soil is fully turned over, the iron-based nanomaterials are added and mixed evenly with the target soil; S2. Transplant the whole plant seedlings into the target soil treated in S1 and continue planting for at least 45 days.

3. The soil remediation method based on iron-based nanomaterials and plants according to claim 2, characterized in that: In S1, the target soil needs to be pretreated before restoration, and the pretreatment includes natural air drying, grinding and removal of animal and plant residues.

4. The soil remediation method based on iron-based nanomaterials and plants according to claim 2, characterized in that: In S2, the content of iron-based nanomaterials in the target soil was 0.1%-0.5% before the plant seedlings were transplanted.

5. The soil remediation method based on iron-based nanomaterials and plants according to claim 2, characterized in that: In S2, the requirements for continuous planting include daytime temperatures of 28-33°C, nighttime temperatures of 18-23°C, and a continuous planting period of no less than 45 days.

6. The soil remediation method based on iron-based nanomaterials and plants according to claim 1, characterized in that: The target soil is arsenic-contaminated soil; during remediation, the TCLP procedure is used to detect arsenic leaching in the remediated arsenic-contaminated soil, and the improved Wenzel extraction method is used to detect changes in the arsenic form distribution in the remediated arsenic-contaminated soil.

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