A method for inhibiting the migration of soil microplastics
Soil conditioners were prepared by analyzing soil characteristics. By utilizing the electrostatic attraction of hematite and gibbsite, the technological gap in inhibiting soil microplastic migration was filled, achieving a targeted and cost-effective effect in inhibiting microplastic migration.
Patent Information
- Application Number
- CN202411643801.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2044-11-18
AI Technical Summary
There is a technological gap in the current technology for risk management of microplastics in soil environment, and effective methods to inhibit the migration of microplastics in soil have not been effectively solved.
By sampling and analyzing soil at different depths, the abundance of microplastics and soil texture were determined. Soil conditioners were prepared based on soil characteristics, and conditioners with corresponding dosages and compositions were added to the surface soil. The electrostatic attraction of hematite and gibbsite was used to adsorb, aggregate, and settle microplastics, thus constructing a microplastic stabilization evaluation method.
This study achieved highly efficient microplastic migration inhibition for different soil types, saving resources, improving remediation efficiency and quality, and providing a scientific basis for optimizing soil microplastic migration inhibition methods.
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Figure CN119426343B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soil new pollutant remediation technology, and in particular to a method for inhibiting the migration of soil microplastics. Background Technology
[0002] Recent scientific discoveries indicate that soil is rife with new pollutants such as microplastics and PFAS. Taking microplastic pollution as an example, it can migrate in the soil environment, entering crop root systems or groundwater aquifers, thus posing a significant threat to food and drinking water safety. While considerable research has been conducted on the migration and fate of microplastics in soil, significant technological gaps remain in the risk management of microplastics in the soil environment.
[0003] In response to this situation, this application proposes a method for inhibiting soil microplastic migration. First, the migration of microplastics is evaluated based on the ratio of microplastic abundance in deep and shallow soil layers. A quantitative relationship for material addition is then established. By adding conditioners of corresponding dosage and composition to the surface soil, the migration of soil microplastics is reduced through adsorption, aggregation, and sedimentation, thereby achieving effective control of soil microplastic pollution risks. Summary of the Invention
[0004] The purpose of this invention is to address the significant technological gaps in the risk management of microplastics in soil environments, and to propose a method for inhibiting the migration of microplastics in soil.
[0005] The technical solution of the present invention: a method for inhibiting the migration of soil microplastics, comprising the following steps:
[0006] Soil samples were taken at different depths to determine microplastic abundance and soil texture;
[0007] The soil conditioner formulation and dosage are determined based on soil characteristics, and the soil conditioner is prepared accordingly.
[0008] Soil conditioner is added to the soil at a specific depth and water is added to adjust the soil moisture content. The treated soil is then maintained.
[0009] The stabilization effect of soil microplastics was evaluated through soil leaching experiments, and the stabilization rate of soil microplastics was obtained.
[0010] Optionally, the step of sampling soil at different depths and determining microplastic abundance and soil texture includes the following steps:
[0011] Soil samples were taken from the shallow soil layer at a depth of 0-10cm and the deep soil layer at a depth of 40-60cm using a soil sampler.
[0012] Microplastic characterization techniques, including infrared spectroscopy and laser confocal microscopy, were used to obtain the abundance of soil microplastics at two depths, denoted as [MP]. 浅层 [MP] 深层 ;
[0013] The ratio of microplastic abundance in deep to shallow soil layers is denoted as [MP]. 深层 / [MP] 浅层 Meanwhile, the texture of the soil at a depth of 0-10cm was analyzed to obtain the content of clay and silt.
[0014] Optionally, the formulation and dosage of the soil conditioner can be determined by:
[0015] Soil clay + silt content ≤ 30% and [MP] 深层 / [MP] 浅层 ≤10%, select hematite only as the formula, add 1-5g of soil conditioner per 100g of soil;
[0016] Soil clay + silt content ≤ 30% and [MP] 深层 / [MP] 浅层 >10%, choose hematite only as the formula, add 5-10g of soil conditioner per 100g of soil;
[0017] Soil clay + silt content >30% and [MP] 深层 / [MP] 浅层 ≤10%, choose 70-90% hematite + 10-30% gibbsite as the formula, add 1-5g of soil conditioner per 100g of soil;
[0018] Soil clay + silt content >30% and [MP] 深层 / [MP] 浅层 >10%, choose 70-90% hematite + 10-30% gibbsite as the formula, and add 5-10g of soil conditioner per 100g of soil.
[0019] Optionally, the preparation method of the soil conditioner includes selecting 150-200 mesh hematite and 150-200 mesh gibbsite as raw materials and mixing them according to a determined formula ratio.
[0020] Optionally, the mixing is carried out using a ball mill with a milling speed of 200-300 rpm and a milling time of 1-2 hours.
[0021] Optionally, after adding the prepared soil conditioner to the soil at a depth of 0-20cm, add water to bring the soil to a saturated moisture content of 50-70%, and then cure the treated soil for 3-7 days.
[0022] Optionally, the soil leaching experiment includes the following steps:
[0023] Take 8-12g of soil before adding materials and after adding materials and curing, respectively, and place them in a Buchner funnel, with a filter membrane placed at the bottom.
[0024] Soil was leached with 0.5-1.5 L of ultrapure water, and the leachate was collected. The abundance c of microplastics in the leachate was analyzed, and the abundance c0 was compared with that of the original soil leachate to obtain the stabilization rate η, as shown in the following formula:
[0025]
[0026] Optionally, the filter membrane is a stainless steel filter membrane with a pore size of 5-20 μm.
[0027] In summary, this application includes at least one of the following beneficial technical effects:
[0028] 1. This invention analyzes actual environmental soil samples to determine the abundance of microplastics at different depths and the texture of shallow soil. Based on the soil characteristics, the formulation and dosage of soil conditioner are determined. For different clay and silt contents and different ratios of microplastic abundance between deep and shallow soils, different proportions of hematite and gibbsite formulations and different dosage ranges are used. Since soils with high clay and silt content are more prone to cracking under natural conditions, which serves as a preferential channel for microplastic migration, a larger dosage is used for soils with even higher clay and silt contents. This makes the soil microplastic migration inhibition method highly targeted, which can meet the needs of different soil types to the greatest extent and effectively improve the effect of soil microplastic migration inhibition.
[0029] 2. This invention uses hematite and gibbsite as raw materials for soil conditioners. Hematite and gibbsite are positively charged, while soil microplastics are negatively charged. Stabilization of microplastics is achieved through electrostatic attraction. Gibbsite, with its stronger positive charge, can better adsorb negatively charged soil microplastics, thus playing a supporting and enhancing role in stabilization. For soils with weak migration, there is no need to add gibbsite, avoiding unnecessary cost and resource waste.
[0030] 3. This invention constructs an original evaluation method for the stabilization effect of microplastics, providing a reliable standard for assessing the effect of soil microplastic migration inhibition. It can accurately measure the effect of soil conditioners and provide a scientific basis for optimizing soil microplastic migration inhibition methods. Through this evaluation method, the formulation and dosage of soil conditioners can be adjusted in a timely manner to ensure that the soil microplastic migration inhibition effect reaches the optimal state, thereby improving the efficiency and quality of remediation.
[0031] 4. In the risk management of soil microplastics, this invention first quantitatively analyzes the abundance of microplastics in soil at different depths, and then rationally determines the amount of material to be added. This method of determining the material dosage based on the specific soil conditions avoids the problem of resource waste or poor treatment effect that may result from blindly adding materials. Through scientific quantitative analysis, it can be ensured that the dosage of added soil conditioner can maximize the inhibition of soil microplastic migration.
[0032] This invention identifies different soil characteristics through sampling and analysis, and employs soil conditioners with varying formulations and dosages to specifically inhibit soil microplastic migration. Using hematite and gibbsite as raw materials, it utilizes electrostatic attraction to stabilize microplastics, with gibbsite providing auxiliary reinforcement. This avoids unnecessary additions to soils with low migration rates, saving costs and resources. This invention also establishes an original method for evaluating the effectiveness of microplastic stabilization, providing reliable standards and scientific basis for assessing and optimizing soil microplastic migration inhibition, thus improving remediation efficiency and quality. Furthermore, this invention first quantitatively analyzes the abundance of soil microplastics and determines the material dosage based on soil conditions, avoiding indiscriminate addition and ensuring effective inhibition of soil microplastic migration. Attached Figure Description
[0033] Figure 1 This is a schematic diagram comparing the abundance of soil microplastics at depths of 5cm and 50cm in Example 1 of the present invention;
[0034] Figure 2 This is a schematic diagram of the texture (clay and silt content) of shallow soils of different land use types in Embodiment 1 of the present invention. Detailed Implementation
[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] Example 1
[0037] The present invention proposes a method for inhibiting the migration of soil microplastics, comprising the following steps:
[0038] Soil samples were taken at different depths to determine microplastic abundance and soil texture:
[0039] In this embodiment, 50 paired soil samples at depths of 5 cm and 50 cm were collected on-site in a city in North China using a soil sampler. The samples covered six land use types: cultivated land, bare land, woodland, grassland, shrubland, and parks and green spaces. The abundance of microplastics in the soil samples was analyzed using laser direct infrared spectroscopy (LDIR). In addition, the soil particle size classification method was adopted according to the classification method of the International Society of Soil Science, classifying soil particles into clay (<0.002 mm), silt (0.002–0.02 mm), and sand (>0.02 mm). The texture of the shallow soil was determined using a laser particle size analyzer (LS13320, Beckman Coulter, USA) under wet conditions, obtaining the abundance of soil microplastics at depths of 5 cm and 50 cm and the texture of shallow soils of different land use types.
[0040] like Figure 1 As shown, the abundance of microplastics at 50 cm depth was lower than that at 5 cm depth at all locations. Specifically, 46% of the locations had a microplastic abundance at 50 cm depth exceeding 10% of that in the shallow soil layer, 50% had an abundance between 1% and 10%, and 4% of the locations had a microplastic abundance at 50 cm depth below 1% of that in the shallow soil layer. In this invention, [MP] 深层 / [MP] 浅层 The thresholds of around 10% cover 46% and 54% of the samples respectively, which is reasonable and can represent the difference ratio of microplastic abundance in deep and shallow soil in real soil.
[0041] like Figure 2 As shown, the average content of clay and silt in soils of different land use types is around 30%, so it is reasonable to select 30% as the threshold for judgment.
[0042] The soil conditioner formulation and dosage are determined based on soil characteristics, and the soil conditioner is prepared accordingly.
[0043] In this embodiment, 180-mesh hematite and gibbsite are used as raw materials. The ball milling speed is 300 rpm and the ball milling time is 1 hour. The soil conditioner is added to the soil at a specific depth and water is added to make the soil reach a saturated moisture content of 60% and then cured for 5 days.
[0044] Typical soil samples were selected from the above soil samples as experimental soils. The soil leaching experiment was used to evaluate the soil microplastic stabilization effect and obtain the soil microplastic stabilization rate. The process included the following steps:
[0045] Take 10g (dry weight) of soil before adding materials and after adding materials and curing, respectively, and place them in a Buchner funnel. Place a stainless steel filter membrane with a pore size of 10μm in the bottom layer.
[0046] Soil was leached with 1L of ultrapure water, and the leachate was collected. The abundance of microplastics in the leachate was analyzed, and the abundance was compared with that of the original soil leachate to obtain the stabilization rate η, as shown in the following formula:
[0047]
[0048] Soil 1: The soil clay + silt content is 25.4%, and [MP] 深层 / [MP] 浅层 The stabilization rate of soil microplastics was 7.6%, achieved by using only hematite as the formulation, with 1-5g of soil conditioner added per 100g of soil. Table 1 below shows the stabilization rates of soil microplastics obtained by adding different amounts of soil conditioner.
[0049]
[0050] Table 1: Stabilization rate of soil microplastics obtained by adding different amounts of soil conditioner to soil 1
[0051] As shown in Table 1, when the dosage is 0.5, the stabilization rate is only 35%. It can be concluded that due to the low dosage of soil conditioner, the stabilization effect of hematite on soil microplastics is not good, and the adsorption and stabilization effect of hematite on microplastics cannot be fully utilized.
[0052] When the dosage is 1, the stabilization rate reaches 82%. At this dosage, hematite begins to play a good role and can effectively adsorb negatively charged soil microplastics, thereby improving the stabilization degree of soil microplastics. When the dosage is 5, the stabilization rate is 96%, which is a further increase compared to the dosage of 1. This indicates that as the dosage of hematite increases, its stabilization effect on soil microplastics also increases.
[0053] When the dosage is 7, the stabilization rate is 98%. Although the stabilization rate is higher than that when the dosage is 5, since the dosage at this time has exceeded the appropriate range (1-5g), it can be concluded that increasing the dosage within a certain range can improve the stabilization effect, but beyond the appropriate range, it will not bring about a significant improvement in effect.
[0054] Example 2
[0055] The difference between this embodiment and Embodiment 1 lies in the clay + silt content and [MP] of the experimental soil. 深层 / [MP] 浅层 different.
[0056] Soil 2: The soil clay + silt content was 26.6%, [MP] 深层 / [MP] 浅层With a content of 20%, using only hematite as the formula, 5-10g of soil conditioner was added to 100g of soil. The stabilization rate of soil microplastics obtained by adding different amounts of soil conditioner is shown in Table 2 below:
[0057]
[0058] Table 2: Stabilization rate of soil microplastics obtained by adding different amounts of soil conditioner to soil 2
[0059] As shown in Table 2, when the dosage is 1, the stabilization rate is 47%, which indicates that due to the low dosage of soil conditioner, the stabilization effect of hematite on soil microplastics is not good and cannot effectively inhibit the migration of soil microplastics. When the dosage is 3, the stabilization rate is 58%, which indicates that the effect of hematite is enhanced at this dosage, but it is still not enough to achieve a good stabilization effect.
[0060] When the dosage is 5%, the stabilization rate is 79%, which is significantly higher than that when the dosage is 3. This indicates that the stabilization effect of hematite on soil microplastics is significantly enhanced with the increase of hematite dosage. When the dosage is 10%, the stabilization rate is 97%, which is a further increase. This shows that at this dosage, hematite has a significant stabilization effect on soil microplastics and achieves the goal of improving the stabilization rate of soil microplastics.
[0061] Example 3
[0062] The difference between this embodiment and Embodiments 1 and 2 lies in the clay + silt content and [MPa] of the experimental soil. 深层 / [MP] 浅层 different.
[0063] Soil 3: The clay + silt content was 49.0%, [MP] 深层 / [MP] 浅层 The stabilization rate of soil microplastics was 5.5%, with a formula of 70-90% hematite and 10-30% gibbsite. 1-5g of soil conditioner was added to 100g of soil. Table 3 shows the stabilization rates of soil microplastics obtained by adding different amounts of soil conditioner.
[0064]
[0065] Table 3: Stabilization rates of soil microplastics obtained by adding different amounts of soil conditioner to soil 3 are shown in Table 3. The soil conditioner formulation is when only hematite is used:
[0066] When the dosage is 1, the stabilization rate is 48%; when the dosage is 5, the stabilization rate is 62%. It can be concluded that for soil 3, even if the dosage is increased, the stabilization rate is low and the stabilization effect is poor when only hematite is used.
[0067] When the soil conditioner formula is 80% hematite + 20% gibbsite:
[0068] When the dosage is 0.5, the stabilization rate is 56%, which shows that although gibbsite is introduced at this dosage, the dosage is insufficient and the stabilization effect is not good.
[0069] When the dosage is 1, the stabilization rate is 83%, which is higher than the stabilization rate when the dosage is 0.5. It can be concluded that the stabilization effect is enhanced after introducing gibbsite and increasing the dosage. Since gibbsite has stronger positive charge, it can better adsorb negatively charged soil microplastics. It works synergistically with hematite to improve the stabilization capacity of soil microplastics.
[0070] When the dosage is 5, the stabilization rate is 95%, and the stabilization effect is further improved. It can be concluded that the combination of hematite and gibbsite can effectively inhibit the migration of soil microplastics.
[0071] When the soil conditioner formula is 90% hematite + 10% gibbsite:
[0072] When the dosage is 1, the stabilization rate is 77%. It can be concluded that the soil conditioner with a formula of 90% hematite + 10% gibbsite can also achieve a good stabilization effect. Although the stabilization rate is slightly lower than that achieved by the soil conditioner with a formula of 80% hematite + 20% gibbsite, it still meets the requirements.
[0073] When the soil conditioner formula is 95% hematite + 5% gibbsite:
[0074] When the dosage is 1, the stabilization rate is 56%, which indicates that the stabilization effect is poor due to the low proportion of gibbsite.
[0075] Example 4
[0076] The difference between this embodiment and Embodiments 1, 2, and 3 lies in the clay + silt content and [MPa] of the experimental soil. 深层 / [MP] 浅层 different.
[0077] Soil 4: The soil clay + silt content is 47.9%, [MP] 深层 / [MP] 浅层 The stabilization rate of soil microplastics was 38.9%. A formula of 70-90% hematite + 10-30% gibbsite was selected, and 5-10g of soil conditioner was added to 100g of soil. The stabilization rates of soil microplastics obtained by adding different amounts of soil conditioner are shown in Table 4 below.
[0078]
[0079]
[0080] Table 4: Stabilization rates of soil microplastics obtained by adding different amounts of soil conditioner to soil 4 are shown in Table 4. The soil conditioner formulation is when only hematite is used:
[0081] When the dosage is 5, the stabilization rate is 36%; when the dosage is 10, the stabilization rate is 51%. It can be concluded that for soil 4, when the soil conditioner formula only uses hematite, the stabilization effect is poor, and even if the dosage is increased, a good stabilization level cannot be achieved.
[0082] When the soil conditioner formula is 80% hematite + 20% gibbsite:
[0083] When the dosage is 4, the stabilization rate is 60%, which is a certain improvement compared to the stabilization rate when only hematite is used. However, due to insufficient dosage, the stabilization effect is not good.
[0084] When the dosage is 5, the stabilization rate is 86%, indicating that the stabilization effect is enhanced after increasing the dosage. The combination of hematite and gibbsite can play a role in effectively inhibiting the migration of soil microplastics.
[0085] When the dosage is 10, the stabilization rate is 92%, and the stabilization effect is further improved. It can be concluded that increasing the dosage can further improve the stabilization capacity of soil microplastics.
[0086] When the soil conditioner formula is 90% hematite + 10% gibbsite:
[0087] When the dosage is 5, the stabilization rate is 75%. It can be concluded that the soil conditioner with a formula of 90% hematite + 10% gibbsite can also achieve a good stabilization effect. Although the stabilization rate is slightly lower than that achieved by the soil conditioner with a formula of 80% hematite + 20% gibbsite, it still meets the requirements.
[0088] When the soil conditioner formula is 95% hematite + 5% gibbsite:
[0089] When the dosage is 5%, the stabilization rate is 52%, indicating that the stabilization effect is poor due to the low proportion of gibbsite in this formula.
[0090] This invention identifies different soil characteristics through sampling and analysis, and employs soil conditioners with varying formulations and dosages to specifically inhibit soil microplastic migration. Using hematite and gibbsite as raw materials, it utilizes electrostatic attraction to stabilize microplastics, with gibbsite providing auxiliary reinforcement. This avoids unnecessary additions to soils with low migration rates, saving costs and resources. This invention also establishes an original method for evaluating the effectiveness of microplastic stabilization, providing reliable standards and scientific basis for assessing and optimizing soil microplastic migration inhibition, thus improving remediation efficiency and quality. Furthermore, this invention first quantitatively analyzes the abundance of soil microplastics and determines the material dosage based on soil conditions, avoiding indiscriminate addition and ensuring effective inhibition of soil microplastic migration.
[0091] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.
Claims
1. A method for inhibiting the migration of soil microplastics, characterized in that, Includes the following steps: Soil samples were taken at different depths to determine microplastic abundance and soil texture; The soil conditioner formulation and dosage are determined based on soil characteristics, and the soil conditioner is prepared accordingly. Soil conditioner is added to the soil at a specific depth and water is added to adjust the soil moisture content. The treated soil is then maintained. The stabilization effect of soil microplastics was evaluated through soil leaching experiments, and the stabilization rate of soil microplastics was obtained. The process of sampling soil at different depths and determining microplastic abundance and soil texture includes the following steps: Soil samples were taken from the shallow soil layer at a depth of 0-10cm and the deep soil layer at a depth of 40-60cm using a soil sampler. Microplastic characterization techniques, including infrared spectroscopy and laser confocal microscopy, were used to obtain the abundance of soil microplastics at two depths, denoted as [MP]. 浅层 [MP] 深层 ; The ratio of microplastic abundance in deep to shallow soil layers is denoted as [MP]. 深层 / [MP] 浅层 Meanwhile, the texture of the soil at a depth of 0-10cm was analyzed to obtain the content of clay and silt. The methods for determining the formulation and dosage of the soil conditioner include: Soil clay + silt content ≤30% and [MP] 深层 / [MP] 浅层 ≤10%, select hematite only as the formula, add 1-5g of soil conditioner per 100g of soil; Soil clay + silt content ≤30% and [MP] 深层 / [MP] 浅层 >10%, choose hematite only as the formula, add 5-10g of soil conditioner per 100g of soil; Soil clay + silt content >30% and [MP] 深层 / [MP] 浅层 ≤10%, choose 70-90% hematite + 10-30% gibbsite as the formula, add 1-5g of soil conditioner per 100g of soil; Soil clay + silt content >30% and [MP] 深层 / [MP] 浅层 >10%, choose 70-90% hematite + 10-30% gibbsite as the formula, add 5-10g of soil conditioner per 100g of soil; The preparation method of the soil conditioner includes selecting 150-200 mesh hematite and 150-200 mesh gibbsite as raw materials and mixing them according to a determined formula ratio.
2. The method for inhibiting soil microplastic migration according to claim 1, characterized in that, The mixing is carried out using a ball mill with a milling speed of 200-300 rpm and a milling time of 1-2 hours.
3. The method for inhibiting soil microplastic migration according to claim 1, characterized in that, After adding the prepared soil conditioner to the soil at a depth of 0-20cm, add water to bring the soil to a saturated moisture content of 50-70%, and then cure the treated soil for 3-7 days.
4. The method for inhibiting soil microplastic migration according to claim 1, characterized in that, The soil leaching experiment includes the following steps: Take 8-12g of soil before adding materials and after adding materials and curing, respectively, and place them in a Buchner funnel, with a filter membrane placed at the bottom. Soil was leached with 0.5–1.5 L of ultrapure water, the leachate was collected, and the abundance of microplastics in the leachate was analyzed. The abundance and the abundance of the original soil leachate By making comparisons, the stabilization rate can be obtained. The formula is as follows: 。 5. The method for inhibiting soil microplastic migration according to claim 4, characterized in that, The filter membrane uses 5-20. Stainless steel filter membrane with specific pore size.