A method for repairing soil heavy metal pollution based on nanomaterials

Abstract

The present application relates to the field of environmental remediation, and discloses a soil heavy metal pollution remediation method based on nanomaterials, which is especially suitable for remediation of copper, lead, cadmium and other heavy metal contaminated soils. The method uniformly adds nanomaterials to the contaminated soil, uses the high specific surface area and strong adsorption of nanomaterials to adsorb or reduce heavy metal ions in the soil to low-toxic or non-toxic forms, thereby effectively reducing the concentration of heavy metals in the soil. The nanomaterials in the remediation process can improve their stability and adsorption capacity through surface modification, enhancing the remediation effect. By adjusting the humidity, pH value and other parameters of the soil, the remediation conditions are optimized, and the remediation efficiency is improved. The present application has the advantages of fast remediation speed, low cost, environmental friendliness, etc., and is especially suitable for rapid treatment of large-area heavy metal contaminated soil, can significantly reduce the migration and bioavailability of heavy metals in the soil, avoid secondary pollution problems, and has broad application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental remediation, and particularly relates to a soil heavy metal pollution remediation method based on nanomaterials. BACKGROUND

[0002] With the acceleration of industrialization and urbanization, the problem of heavy metal pollution in soil is becoming increasingly serious. A large amount of industrial wastewater discharge, overuse of pesticides and fertilizers, mineral exploitation and other activities have led to heavy metal pollution in soil, such as lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), mercury (Hg), etc., which has seriously affected the ecological environment and agricultural production, and has posed a threat to human health. The heavy metal contaminated soil is difficult to restore itself through natural processes, and the pollutants can accumulate through the food chain, ultimately affecting human health.

[0003] At present, there has been some progress in soil remediation technology. Traditional remediation methods mainly include physical remediation, chemical remediation and biological remediation methods. Although these methods can effectively remove heavy metal pollution in soil to some extent, there are still many deficiencies.

[0004] Physical remediation methods, such as soil replacement and aeration, are simple and effective, but have the following problems:

[0005] High remediation cost: Physical methods require a large amount of soil transportation or equipment investment, and the cost is extremely high when the treatment area is large, making it difficult to be applied on a large scale.

[0006] Limited effect: Physical methods mainly isolate or dilute heavy metals through physical means, but cannot effectively degrade or remove heavy metal ions in soil. The residual pollutants in soil may migrate to groundwater or air again.

[0007] Secondary pollution problem: Some chemical remediation methods convert heavy metals into insoluble or low-toxic compounds by reacting with chemical reagents in soil. However, these chemical reagents may cause secondary pollution during application, leading to further deterioration of soil quality.

[0008] Unstable remediation effect: The effect of chemical remediation depends on changes in environmental factors such as soil pH and temperature, and the chemical remediation reaction usually needs a long time to complete, making it difficult to achieve effective remediation in a short period of time.

[0009] High remediation cost: A large amount of chemical reagents is used, and needs to be replenished or replaced regularly, resulting in high operating costs.

[0010] High remediation cost: A large amount of chemical reagents is used, and needs to be replenished or replaced regularly, resulting in high operating costs.

[0011] Bioremediation methods use microorganisms or plants to absorb and transform heavy metals, thereby remediating soil pollution. Although bioremediation methods are considered a low-cost and environmentally friendly remediation approach, they still have the following shortcomings:

[0012] Slow remediation speed: Bioremediation usually takes a long time to significantly reduce heavy metal concentrations, and for some heavily contaminated soils, bioremediation is difficult to achieve the desired effect quickly.

[0013] Poor applicability: Bioremediation methods are greatly affected by soil type, environmental conditions, and other factors, and have poor remediation effects for some heavy metals, making it difficult to be applied on a large scale.

[0014] Nanomaterials have been widely used in heavy metal remediation due to their large specific surface area and high reactivity, such as nanoscale zero-valent iron, nanoscale titanium oxide, and nanoscale zinc oxide. However, existing nanomaterials still have the following problems in practical application:

[0015] Poor material stability: Many nanomaterials are prone to aggregation or oxidation, resulting in decreased remediation effectiveness. In particular, nanoscale zero-valent iron is easily oxidized in air, losing its reducing effect.

[0016] Insufficient environmental risk assessment: Nanomaterials may be released into the environment during the remediation process, posing potential ecological risks, especially when they migrate to groundwater or other environmental media, which may have unpredictable effects on the environment.

[0017] High cost and manufacturing difficulty: The preparation cost of nanomaterials is relatively high, and the preparation process is complex, limiting their large-scale application.

[0018] Existing soil heavy metal pollution remediation technologies have their own advantages, but also have certain limitations, including high remediation cost, unstable effect, secondary pollution risk, and limited application range. Therefore, it is urgent to develop a high-efficiency, low-cost, and secondary pollution-free remediation technology to meet the soil remediation needs under different pollution conditions and environmental conditions. Using nanomaterials for soil remediation, combined with their excellent adsorption, reduction, and catalytic properties, is expected to become an effective solution to break through the bottlenecks of existing technologies.

[0019] Therefore, we urgently need to design a soil heavy metal pollution remediation method based on nanomaterials to solve the above problems. SUMMARY

[0020] The purpose of the present application is to solve the above technical problems and provide a soil heavy metal pollution remediation method based on nanomaterials.

[0021] The above purpose of the present application is achieved as follows:

[0022] A soil heavy metal pollution remediation method based on nanomaterials, the method comprising the following steps:

[0023] 1) Soil sampling and detection: sampling from contaminated soil, detecting heavy metal pollutant types and their concentrations, and analyzing soil physical and chemical properties including pH value, humidity, particle composition, and organic matter content;

[0024] 2) Nanomaterial preparation and modification: preparing nanomaterials with a specific surface area greater than 20 m2 / g, and modifying the nanomaterials according to different heavy metal pollution types to enhance their adsorption and reduction performance,

[0025] 3) Nanomaterial dosage calculation: calculating the dosage of nanomaterials according to the heavy metal concentration of the soil, the soil quality, and the remediation target, and the calculation formula is:

[0026]

[0027] Wherein, C m is the dosage of nanomaterials (unit: kg), C s is the heavy metal concentration in the soil (unit: mg / kg), V s is the soil quality (unit: kg), a is the adsorption capacity of nanomaterials (unit: mg / g), and k is the remediation efficiency coefficient, with a value range of 0.8-1.0;

[0028] 4) Remediation operation: uniformly mixing the nanomaterials in the contaminated soil, adjusting the humidity and pH value of the soil, and controlling the reaction time to ensure the remediation effect of the nanomaterials;

[0029] 5) Remediation effect evaluation: detecting the change in heavy metal concentration in the soil after remediation, calculating the heavy metal removal efficiency, and the calculation formula is:

[0030]

[0031] Wherein, η is the removal efficiency (unit: %), C i is the heavy metal concentration in the soil before remediation (unit: mg / kg), and C f is the heavy metal concentration in the soil after remediation (unit: mg / kg).

[0032] As a preferred technical solution of the present application, the soil sampling also needs to measure the organic matter content, particle composition, and soil bulk density in the soil, and the heavy metal pollutants include but are not limited to lead (Pb 2 +), cadmium (Cd 2 +), chromium (Cr 3 +), and copper (Cu 2 +).

[0033] As a preferred technical scheme of the present application, the nanomaterial is nanometer zero-valent iron (nZVI), nanometer titanium dioxide (TiO2) or nanometer zinc oxide (ZnO), wherein the nanometer zero-valent iron is prepared by chemical reduction method, the particle size range is 10-100 nm, and the specific surface area is greater than 30 m2 / g.

[0034] As a preferred technical scheme of the present application, the surface modification material of the nanomaterial is selected from polymers, oxides, silicate materials, carbon materials, metal oxides, phosphates and combinations thereof.

[0035] As a preferred technical scheme of the present application, the dosage of the nanomaterial is calculated according to the following formula:

[0036]

[0037] wherein C m is the dosage of the nanomaterial (unit: kg), C s is the concentration of heavy metals in the contaminated soil (unit: mg / kg), V s is the soil quality (unit: kg), a is the adsorption capacity of the nanomaterial (unit: mg / g), and k is the remediation efficiency coefficient, which is in the range of 0.8-1.0. The calculation formula can be adjusted according to the type and target concentration of soil heavy metal pollution.

[0038] As a preferred technical scheme of the present application, in the remediation operation, the dosage of the nanomaterial is 1-5%, and the nanomaterial is fully mixed with the contaminated soil by stirring.

[0039] As a preferred technical scheme of the present application, in the remediation process, the pH value of the soil is adjusted to the range of 5.5-7.5, and the optimal pH value is 6.5. This pH value range can maximize the removal efficiency of the nanomaterial.

[0040] As a preferred technical scheme of the present application, the nanomaterial is combined with the heavy metal ions through chelation reaction to form a stable complex, and the chemical reaction formula is:

[0041] M n+ + Fe 0 → M(Fe) n+ ;

[0042] wherein M n+ is a heavy metal ion, Fe 0 is nanometer zero-valent iron, and M(Fe) n+ is the formed heavy metal-iron complex.

[0043] As a preferred technical scheme of the present application, in the remediation process, the humidity of the soil is controlled in the range of 20%-30% to optimize the reaction rate and effect of the nanomaterial and the heavy metal ions.

[0044] As a preferred technical solution of the present application, the repair effect evaluation comprises the following steps:

[0045] The heavy metal concentration of the repaired soil is detected, and the detection method comprises atomic absorption spectrometry (AAS) or inductively coupled plasma mass spectrometry (ICP-MS);

[0046] The removal effect is calculated according to the removal efficiency calculation formula;

[0047] The repair effect is evaluated by comparing the heavy metal concentration changes of the soil before and after repair.

[0048] Compared with the prior art, the present application has the following beneficial effects:

[0049] The present application uses nanomaterials to repair soil heavy metal pollution, and effectively removes copper, lead, cadmium and other heavy metals in the soil by using the high specific surface area and strong adsorption of nanomaterials. By reacting nanomaterials with heavy metal ions, the pollutants can be reduced to low-toxic or non-toxic forms, significantly reducing the concentration of heavy metals in the soil.

[0050] The repair method of the present application is simple to operate, the material cost is low, and the repair process does not require complex equipment or expensive chemical reagents, and has good economic benefits. By reasonably selecting and optimizing the type and dosage of nanomaterials, efficient repair can be achieved at a lower cost, and it is suitable for the treatment of large-area contaminated soil.

[0051] Compared with traditional repair methods, the nanomaterials used in the present application have good stability and environmental compatibility, and the repair process will not cause secondary pollution. In the repair process, nanomaterials can effectively react with heavy metal ions in the soil, avoiding the secondary pollution problem that may be caused by traditional chemical repair methods, ensuring the green and environmental protection of the repair process. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0053] Figure 1 It is a flowchart of a soil heavy metal pollution repair method based on nanomaterials. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0055] The specific embodiments of the present application are described in detail below in combination with the drawings in the present application. Figure 1 The specific embodiments of the present application are described in detail below in combination with the drawings in the present application.

[0056] Embodiment one: nano zero-valent iron is used to repair lead contaminated soil.

[0057] 1. Soil sampling and detection: sampling site: select a lead (Pb) contaminated area of an agricultural land, take a soil sample V s = 10 kg.

[0058] Detect the pollution concentration: use ICP-MS to detect the initial lead concentration C s = 120 mg / kg.

[0059] 2. Nano zero-valent iron dosage calculation:

[0060] The dosage of nano zero-valent iron C m is calculated by the following formula:

[0061]

[0062] Wherein: C s = 120 mg / kg: initial soil lead concentration. V s = 10 kg: soil mass. α = 100 mg / g: unit adsorption capacity of nano zero-valent iron. k = 0.8: repair efficiency coefficient.

[0063] Substitute the data:

[0064]

[0065] 3. Repair operation steps:

[0066] Nano material preparation: prepare a nano zero-valent iron dispersion solution with a concentration of 5 g / L, 3 L o

[0067] Soil mixing: place the soil sample in the reactor, uniformly spray the nano material dispersion solution, and fully stir and mix.

[0068] Reaction conditions: humidity: 25%; temperature: 25℃; reaction time: 24 hours;

[0069] 4. Repair effect detection: lead concentration C s = 120 mg / kg.

[0070] Lead concentration C after treatment r = 24 mg / kg.

[0071] Removal rate calculation:

[0072]

[0073] Results: The removal rate of lead reached 80%, indicating that nano zero-valent iron has good repair effect on lead-contaminated soil.

[0074] Example Two: Nano Zinc Oxide Repairing Copper-Contaminated Soil

[0075] 1. Soil sampling and detection: Sampling site: select a copper (Cu) contaminated area, take soil sample V s = 8 kg.

[0076] Detect the concentration of pollution: initial copper concentration C s = 160 mg / kg.

[0077] 2. Nano zinc oxide dosage calculation:

[0078] The dosage of nano zinc oxide C m The calculation formula is also:

[0079]

[0080] Parameter setting:

[0081] C s = 160 mg / kg: initial copper concentration.

[0082] V s = 8 kg: soil mass.

[0083] α = 200 mg / g: unit adsorption capacity of nano zinc oxide.

[0084] k = 0.85: repair efficiency coefficient.

[0085] Substitute the data:

[0086]

[0087] 3. Repair operation steps:

[0088] Nano material solution preparation: prepare 2.5 g / L nano zinc oxide dispersion liquid, 3.0 L is needed.

[0089] Soil mixing: evenly spray the dispersion liquid into the soil sample and stir thoroughly.

[0090] Reaction conditions: Humidity: 20%; Temperature: 28°C; Reaction time: 48 hours; 4. Repair effect detection: Copper concentration C s = 160 mg / kg.

[0091] Copper concentration C r = 32 mg / kg.

[0092] Removal rate calculation:

[0093]

[0094] Result: The removal rate of copper reached 80%, indicating that nano zinc oxide has a significant repair effect on copper-contaminated soil.

[0095] Example Three: Nano titanium dioxide repairing cadmium-contaminated soil;

[0096] 1. Soil sampling and detection: Sampling site: select a cadmium (Cd) contaminated area in an industrial area, take soil sample V s = 5 kg.

[0097] Detect the concentration of pollution: Initial cadmium concentration C s = 50 mg / kg.

[0098] 2. Nano titanium dioxide dosage calculation

[0099] Parameter setting: C s = 50 mg / kg: initial cadmium concentration.

[0100] V s = 5 kg: soil mass.

[0101] α = 50 mg / g: unit adsorption capacity of nano titanium dioxide.

[0102] k = 0.75: repair efficiency coefficient.

[0103] Substitute the formula:

[0104]

[0105] 3. Repair operation steps: Reaction conditions:

[0106] Material preparation: Prepare 3 g / L of nano titanium dioxide dispersion liquid, which needs to be prepared 2.2 L.

[0107] Soil mixing: evenly spray nano materials and mix by stirring.

[0108] Humidity: 30%; Temperature: 30°C; Reaction time: 72 hours.

[0109] 4. Repair effect detection: cadmium concentration C s = 50 mg / kg. Cadmium concentration C r = 10 mg / kg after treatment.

[0110] Removal rate calculation:

[0111]

[0112] Results: The removal rate of cadmium reached 80%, indicating that the application effect of nano titanium dioxide in cadmium contaminated soil was good.

[0113] Summary: The above examples respectively verify the application effect of nano zero-valent iron, nano zinc oxide and nano titanium dioxide in repairing lead, copper and cadmium contaminated soil, and the removal rate is more than 80%, indicating that the nano material repair method of the application has wide applicability and significant repair effect.

[0114] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for remediation of heavy metal contaminated soil based on nanomaterials, characterized in that, The method comprises the following steps: 1) soil sampling and detection: sampling from contaminated soil, detecting the types and concentrations of heavy metal pollutants, and analyzing the physical and chemical properties of the soil, including pH, humidity, particle composition, and organic matter content; 2) nanomaterial preparation and modification: preparing nanomaterials with a specific surface area greater than 20 m2 / g, and modifying the nanomaterials according to different types of heavy metal pollution, 3) calculation of nanomaterial dosage: according to the concentration of heavy metals in the soil, the quality of the soil, and the repair target, the dosage of the nanomaterials is calculated, and the calculation formula is: Wherein, C m is the dosage of nanomaterials, C s is the concentration of heavy metals in soil, V s is the soil quality, and α is the adsorption capacity of nanomaterials, k is the repair efficiency coefficient, and the value range is 0.8-1.

0. The nanomaterials include but are not limited to nanometer zero-valent iron nZVI, nanometer titanium dioxide TiO2, or nanometer zinc oxide ZnO, wherein the nanometer zero-valent iron is prepared by chemical reduction method, the particle size range is 10-100 nm, and the specific surface area is greater than 30 m2 / g, the surface modification material of the nanomaterials is selected from polymers, oxides, silicates, carbon materials, metal oxides, phosphates, and combinations thereof; 4) repair operation: uniformly mixing the nanomaterials in the contaminated soil, adjusting the humidity and pH of the soil, and controlling the reaction time; 5) repair effect evaluation: after repair, the concentration of heavy metals in the soil is detected, the removal efficiency of heavy metals is calculated, and the calculation formula is: Wherein, η is removal efficiency, C i C is the concentration of heavy metals in the soil before remediation, f C is the concentration of heavy metals in the soil after remediation.

2. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, When the soil is sampled, the organic matter content, particle composition and soil bulk density in the soil also need to be determined, and the heavy metal pollutants include but are not limited to lead Pb 2 +、cadmium Cd 2 +、chromium Cr 3 +、copper Cu 2 + 3. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, In the repair operation, the dosage of the nanomaterials is 1-5%, and the nanomaterials are fully mixed with the contaminated soil by stirring.

4. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, In the repair process, the pH of the soil is adjusted to a range of 5.5-7.

5.

5. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, The nanomaterials are combined with heavy metal ions through chelation reaction to form stable complexes, and the chemical reaction formula is: M n+ + Fe 0 → M(Fe) n+ ; wherein M n+ is a heavy metal ion, Fe 0 is nano zero-valent iron, M(Fe) n+ is a heavy metal-iron complex formed.

6. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, In the repair process, the humidity of the soil is controlled within a range of 20%-30%.

7. The method for remediation of heavy metal contaminated soil based on nanomaterials according to claim 1, characterized in that, The repair effect evaluation comprises the following steps: Detecting the concentration of heavy metals in the repaired soil, the detection method of heavy metal concentration detection includes atomic absorption spectrometry or inductively coupled plasma mass spectrometry; According to the removal efficiency calculation formula, the removal effect is calculated; By comparing the concentration changes of heavy metals in the soil before and after repair, the repair effect is evaluated.

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