Preparation method and application of heavy metal antimony contaminated soil remediation agent

Abstract

The invention discloses a preparation method and application of a heavy metal antimony contaminated soil remediation agent.The preparation method comprises the steps that soluble trivalent iron salt and ultrapure water are mixed, and a trivalent iron salt solution is obtained; adding an alkaline solution into the trivalent ferric salt solution, mixing, and carrying out drying and freeze-drying treatment to obtain an artificially synthesized mineral material; the method comprises the following steps: reducing an artificially synthesized mineral material in an anaerobic environment through a mode iron reduction strain, freeze-drying and collecting to obtain a modified synthesized mineral material; and the modified synthetic mineral material and an oxidizing agent are jointly used according to a preset mixing ratio, and the heavy metal antimony contaminated soil remediation agent is obtained. The technical problems that in the prior art, a repairing agent generates secondary pollution to the environment, the repairing efficiency is low, and the repairing effect is not durable are solved.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal antimony contaminated soil remediation, and specifically to a preparation method and application of a heavy metal antimony contaminated soil remediation agent. Background Art

[0002] Antimony (Sb) is located in the fifth period, main group V of the periodic table. It is a trace but ubiquitous toxic element in the environment and a non-essential element for organisms. The toxicity of antimony is related to its oxidation state. The toxicity of antimony in different valence states is in the following order: Sb(III)>Sb(V). In addition, inorganic antimony is more toxic than organic antimony. Antimony is listed as a priority controlled substance by the U.S. Environmental Protection Agency and the European Union, and as a key heavy metal pollutant by China. Antimony has been proven to be toxic and carcinogenic to humans and organisms, and can cause liver, skin, respiratory and cardiovascular diseases, and has a long incubation period. Antimony in the environment mainly comes from rock weathering, antimony mining and smelting, and the widespread use of antimony compounds. During the mining and smelting process, antimony is released from the ore, causing environmental pollution.

[0003] At present, the more common remediation solutions for heavy metal antimony pollution include physical / chemical remediation technology, biological remediation technology, agricultural ecological restoration technology, etc.

[0004] Physical / chemical remediation technologies include soil leaching technology, solidification / stabilization technology, redox technology, etc. Such remediation technologies often have good remediation effects, but they have problems such as high remediation costs, difficult technical requirements, and easy secondary pollution.

[0005] Bioremediation technology is a sustainable remediation method that uses organisms to participate in the degradation and elimination of environmental pollutants. Its remediation cost is low, the technology is simple, and there is no secondary pollution, but it is greatly restricted by environmental factors.

[0006] Agricultural ecological restoration technology refers to the use of reasonable and effective farming management systems to improve the heavy metal pollution of farmland during the process of growing crops, mainly including agronomic restoration measures and ecological restoration measures. The advantages of this type of restoration technology are low cost and simple operation, and it basically does not change the planting habits of the restored agricultural land. However, its restoration cycle is long, and the effect of large-scale experiments needs further exploration. Summary of the invention

[0007] The purpose of the present invention is to provide a preparation method and application of a heavy metal antimony contaminated soil remediation agent in order to solve at least one of the above technical problems.

[0008] In the first aspect, an embodiment of the present invention provides a method for preparing a heavy metal antimony contaminated soil remediation agent, comprising: mixing a soluble trivalent iron salt with ultrapure water to obtain a trivalent iron salt solution; adding an alkaline solution to the trivalent iron salt solution, mixing, and drying and freeze-drying to obtain an artificially synthesized mineral material; reducing the artificially synthesized mineral material under an anaerobic environment by a model iron-reducing strain, and freeze-drying and collecting to obtain a modified synthetic mineral material; and using the modified synthetic mineral material in combination with an oxidant in a preset ratio to obtain a heavy metal antimony contaminated soil remediation agent.

[0009] Furthermore, the soluble ferric iron salt comprises at least one of the following: FeCl 3 , Fe 2 (SO 4 ) 3 、Fe(NO 3 ) 3 .

[0010] Furthermore, the alkaline solution includes KOH solution or NaOH solution.

[0011] Furthermore, the mass fraction ratio of the trivalent iron salt solution to the alkaline solution is 1:1.8.

[0012] Furthermore, the model iron-reducing strain includes Geobacter and / or Shewanella.

[0013] Furthermore, the oxidant includes hydrogen peroxide.

[0014] Furthermore, the preset mixing ratio includes: the modified synthetic mineral material: the oxidant = 1g: 2ml to 1g: 4ml.

[0015] In a second aspect, an embodiment of the present invention further provides an application of a heavy metal antimony contaminated soil remediation agent, comprising: drying and crushing the contaminated soil to be remediated to obtain pretreated contaminated soil; using a stirring and mixing device to evenly mix the pretreated contaminated soil with the heavy metal antimony contaminated soil remediation agent to obtain mixed contaminated soil; covering the surface of the mixed contaminated soil with a moisturizing material, and obtaining the remediated soil after curing for a preset time.

[0016] Furthermore, the moisture content of the contaminated soil after the pretreatment is 10%-30%, and the particle size is 1cm-3cm; the usage mass of the heavy metal antimony contaminated soil remediation agent is 1%-2% of the mass of the contaminated soil to be remediated.

[0017] Furthermore, the contaminated soil after the pretreatment is evenly mixed with the heavy metal antimony contaminated soil remediation agent using a stirring and mixing device to obtain the mixed contaminated soil, including: using a stirring and mixing device to evenly mix the contaminated soil after the pretreatment with the modified synthetic mineral material, then adding the oxidant in a preset proportion, and mixing again to obtain the mixed contaminated soil.

[0018] The present invention provides a preparation method and application of a heavy metal antimony contaminated soil remediation agent. By preparing synthetic mineral materials and utilizing microbial modification, the specific surface area and surface binding energy of the mineral are increased, the hydroxyl content is improved, the adsorption performance is good, the secondary pollution and other problems are avoided, and the advantages of high stabilization efficiency, fast remediation speed, high durability, etc. are alleviated. The technical problems existing in the prior art of remediation agents causing secondary pollution to the environment, low remediation efficiency, and short-lasting remediation effect are alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the implementation methods of the present application 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 some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A flow chart of a method for preparing a heavy metal antimony contaminated soil remediation agent provided in an embodiment of the present invention;

[0021] Figure 2 A flowchart of the application of a heavy metal antimony contaminated soil remediation agent provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Figure 1 The flowchart of the preparation method of a heavy metal antimony contaminated soil remediation agent provided in accordance with an embodiment of the present invention is as follows. Figure 1 As shown, the method specifically comprises the following steps:

[0024] Step S102, mixing soluble trivalent iron salt with ultrapure water to obtain a trivalent iron salt solution.

[0025] Preferably, the soluble ferric iron salt comprises at least one of the following: FeCl 3 , Fe 2 (SO 4 ) 3 、Fe(NO 3 ) 3 .

[0026] Step S104, adding an alkaline solution to the ferric salt solution, mixing, and performing drying and freeze-drying treatment to obtain an artificially synthesized mineral material.

[0027] Preferably, the alkaline solution comprises a KOH solution or a NaOH solution.

[0028] Preferably, the mass fraction ratio of the ferric salt solution to the alkaline solution is 1:1.8.

[0029] Specifically, a soluble trivalent iron salt and ultrapure water are mixed to prepare a trivalent iron salt solution with a concentration of 1 mol / L, and then 1.8 parts of KOH or NaOH solution with a concentration of 5 mol / L are added to the trivalent iron salt solution, and then a certain amount of ultrapure water is added, and the suspension is transferred to an electric heated blast drying oven and cultured at 70°C for 60 hours, and the light yellow solid precipitate in the suspension obtained after drying is collected, washed twice with water, and then freeze-dried and collected to obtain an artificially synthesized mineral material (goethite).

[0030] Step S106, reducing the artificial synthetic mineral material by a model iron-reducing strain under an anaerobic environment, and collecting by freeze-drying to obtain a modified synthetic mineral material.

[0031] Preferably, the model iron-reducing strain comprises Geobacter and / or Shewanella.

[0032] Specifically, the artificial synthetic mineral material is reduced by a model iron-reducing strain under an anaerobic environment for 7 days, and freeze-dried and collected to obtain a modified synthetic mineral material.

[0033] Step S108, combining the modified synthetic mineral material and the oxidant in a preset ratio to obtain a heavy metal antimony contaminated soil remediation agent.

[0034] Preferably, the oxidant comprises hydrogen peroxide (H 2 O 2 ).

[0035] In an embodiment of the present invention, the preset mix ratio includes:

[0036] Modified synthetic mineral material: oxidant = 1g:2ml~1g:4ml.

[0037] Preferably, modified synthetic mineral material: oxidant = 1 g: 3 ml.

[0038] The heavy metal antimony contaminated soil remediation agent provided in the embodiment of the present invention has the following remediation principle for the heavy metal antimony contaminated soil:

[0039] ① Antimony is an iron-loving and sulfur-loving element, and is often adsorbed on the surface of iron-manganese oxides. Compared with Sb(III), Sb(V) is less toxic. By adding iron oxides, Sb(III) in the contaminated soil can be oxidized to Sb(V) to eliminate the toxicity of Sb(III).

[0040] ② According to the Haber-Weiss theory, in the natural environment, the reaction of Fe(Ⅱ) in iron-containing minerals such as iron clay minerals, iron sulfides and iron oxides with oxygen can produce abundant reactive oxidative species (ROS) such as hydroxyl radicals (·OH) with strong oxidative properties, i.e., a Fenton-like reaction. This reaction can be used to oxidize Sb(Ⅲ) in contaminated soil to low-toxic Sb(Ⅴ).

[0041] ③ The artificially synthesized mineral material synthesized in the embodiment of the present invention, that is, the iron oxide mineral material (goethite), can reach nanometer or micrometer-sized particles. This type of synthetic goethite has a higher specific surface area, a larger surface binding energy, and carries a positive charge and a higher hydroxyl content, and has better adsorption performance. Through the model iron-reducing strain, the Fe(III) in the artificially synthesized mineral material is reduced to Fe(II), and then participates in the reaction in ② to produce active oxidative species (ROS) to eliminate the toxicity of heavy metal antimony. At the same time, biological reduction of goethite has no significant effect on the mineral crystal form, and can cause the reduced mineral to still have a larger specific surface area, and show better adsorption performance for antimony elements.

[0042] Example

[0043] Figure 2 This is a flowchart of the application of a heavy metal antimony contaminated soil remediation agent provided according to an embodiment of the present invention. Figure 2 As shown, the application specifically includes the following steps:

[0044] Step S202, drying and crushing the contaminated soil to be remediated to obtain pre-treated contaminated soil.

[0045] Preferably, the moisture content of the contaminated soil after pretreatment is 10%-30%, and the particle size is 1cm-3cm.

[0046] Step S204, using a stirring and mixing device to evenly mix the pretreated contaminated soil with a heavy metal antimony contaminated soil remediation agent to obtain mixed contaminated soil.

[0047] Specifically, the contaminated soil after pretreatment is mixed evenly with the modified synthetic mineral material by using a stirring and mixing device, and then an oxidant is added in a preset proportion and mixed evenly again to obtain mixed contaminated soil.

[0048] Preferably, the mass of the heavy metal antimony contaminated soil remediation agent used is 1%-2% of the mass of the contaminated soil to be remediated.

[0049] Step S206, covering the surface of the mixed contaminated soil with a moisture retaining material, and curing for a preset time to obtain repaired soil.

[0050] Preferably, the preset curing time is 3 days.

[0051] According to the application method provided in the embodiment of the present invention, the heavy metal antimony contaminated soil sample was tested. First, the soil sample was pre-treated according to the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T299-2007), and the total amount of antimony in the soil sample and its leaching toxicity concentration were detected; then, the soil sample was maintained and repaired according to the application method provided in the embodiment of the present invention, and the leaching toxicity of antimony was tested again after the repair. The test results are shown in Table 1 below:

[0052] Table 1 Test results

[0053]

[0054] The above data show that after remediation, heavy metal antimony can reach the remediation target value after 3 days of maintenance, the stabilization remediation efficiency is high, and after stabilization for 0.5 to 2 years, the soil antimony leaching concentration is stabilized below the target value, and the remediation agent shows the characteristics of remediation durability; the original soil pH change is only 0.08, which has little effect on the soil pH and less secondary pollution to the external environment.

[0055] From the above description, it can be seen that the preparation method and application of a heavy metal antimony contaminated soil remediation agent provided in an embodiment of the present invention, in response to the problem of secondary pollution existing in the current chemical remediation technology, adopts modified synthetic mineral materials and combines oxidants as remediation agents to remediate antimony contaminated soil, which has a fast effect, a high stabilization rate, will not cause secondary pollution to the environment, and solves the problem of repair durability.

[0056] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0057] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a heavy metal antimony contaminated soil remediation agent, characterized in that: include: mixing a soluble ferric salt with ultrapure water to obtain a ferric salt solution; adding an alkaline solution to the trivalent iron salt solution, mixing the mixture, and performing drying and freeze-drying treatment to obtain an artificially synthesized mineral material; The artificially synthesized mineral material is reduced by a model iron-reducing strain under an anaerobic environment, and freeze-dried and collected to obtain a modified synthetic mineral material; The modified synthetic mineral material and the oxidant are used together in a preset ratio to obtain a heavy metal antimony contaminated soil remediation agent.

2. The method according to claim 1, characterized in that: The soluble trivalent iron salt includes at least one of the following: FeCl3, Fe2(SO4)3, Fe(NO3)3.

3. The method according to claim 1, characterized in that: The alkaline solution includes a KOH solution or a NaOH solution.

4. The method according to claim 1, characterized in that: The mass fraction ratio of the ferric iron salt solution to the alkaline solution is 1:1.

8.

5. The method according to claim 1, characterized in that: The model iron-reducing model strains include Geobacter and / or Shewanella.

6. The method according to claim 1, characterized in that: The oxidant includes hydrogen peroxide.

7. The method according to claim 1, characterized in that: The preset mix ratio includes: The modified synthetic mineral material: the oxidant = 1g:2ml~1g:4ml.

8. An application of the heavy metal antimony contaminated soil remediation agent according to claim 1, characterized in that: include: Drying and crushing the contaminated soil to be remediated to obtain pre-treated contaminated soil; Using a stirring and mixing device to evenly mix the pretreated contaminated soil with the heavy metal antimony contaminated soil remediation agent to obtain mixed contaminated soil; The surface of the mixed contaminated soil is covered with a moisture retaining material, and after curing for a preset time, a repaired soil is obtained.

9. The use according to claim 8, characterized in that: The moisture content of the contaminated soil after the pretreatment is 10%-30%, and the particle size is 1cm-3cm; The usage mass of the heavy metal antimony contaminated soil remediation agent is 1%-2% of the mass of the contaminated soil to be remediated.

10. The use according to claim 8, characterized in that: The contaminated soil after the pretreatment is mixed evenly with the heavy metal antimony contaminated soil remediation agent by using a stirring and mixing device to obtain the mixed contaminated soil, comprising: The pretreated contaminated soil is mixed evenly with the modified synthetic mineral material by using a stirring and mixing device, and then the oxidant is added in a preset proportion and mixed evenly again to obtain the mixed contaminated soil.

Images