Clay mineral colloid repairing agent and method for in-situ fixation of heavy metal-petroleum hydrocarbon composite pollutants

Abstract

The invention relates to the technical field of environmental remediation and pollution treatment, and particularly discloses a clay mineral colloid remediation agent and a method for in-situ immobilization of heavy metal-petroleum hydrocarbon composite pollutants. The clay mineral colloid repairing agent is prepared from montmorillonite or kaolinite and is used for treating composite pollutants including heavy metals and petroleum hydrocarbons. According to the method for in-situ immobilization of the heavy metal-petroleum hydrocarbon composite pollutants, a clay mineral colloid repairing agent is injected into a composite pollution area, heavy metal and petroleum hydrocarbon are induced to generate controllable agglomeration and deposition, a'heavy metal-petroleum hydrocarbon-clay mineral colloid 'ternary system is constructed, and in-situ treatment of the heavy metal-petroleum hydrocarbon composite pollution area is accurately achieved. The composite pollutants can be fixed in situ for a long time, it is ensured that the composite pollutants do not migrate and diffuse for a long time, the stability and safety of pollution treatment are remarkably improved, and the technical problems that an existing remediation technology is lagged in application principle, difficult to adapt to a heavy metal-petroleum hydrocarbon composite pollution system and insufficient in remediation accuracy are solved.

Description

Technical Field

[0001] This application relates to the field of environmental remediation and pollution control technology, and in particular to a clay mineral colloidal remediation agent and a method for in-situ fixation of heavy metal-petroleum hydrocarbon complex pollutants. Background Technology

[0002] With the rapid development of my country's industrialization, industries such as electroplating, ceramics, and manufacturing have become highly concentrated in specific regions, forming numerous industrial clusters. Long-term production activities have led to a widespread threat of combined pollution of soil and groundwater in these areas by heavy metals (HMs) and petroleum hydrocarbons (PHs). This type of combined pollution has complex sources, strong spatial heterogeneity, and the recalcitrant nature of heavy metals and the hydrophobic migration characteristics of petroleum hydrocarbons easily generate complex synergistic effects in the environmental media. The difficulty of remediation is far greater than that of single pollution, making it a global challenge in the field of environmental remediation.

[0003] Among numerous remediation technologies, clay mineral-based in-situ passivation technology is considered a potentially effective technology for treating heavy metal pollution due to its controllable cost and wide applicability. Invention patent CN119479911A describes a method for treating complex heavy metal pollution in soil at non-ferrous smelting sites. The technical process includes: site investigation to obtain soil layout, clay mineral, and heavy metal distribution data; obtaining adsorption parameters through heavy metal adsorption experiments on clay minerals; constructing a "persistence prediction model" to visualize pollution distribution and mineral adsorption potential; determining the types and distribution of passivated clay minerals and the risk of readily available heavy metal states based on the model output; and finally generating a remediation strategy.

[0004] Although the aforementioned invention patents combine the application of clay minerals with model prediction, they are not applicable to the remediation of heavy metal-petroleum hydrocarbon complex pollution for the following reasons: First, the pollution model design is one-sided, only modeling the binary system of "heavy metal-clay minerals" and ignoring the petroleum hydrocarbon co-pollutants commonly found in industrial clusters, resulting in extremely poor applicability of existing models and remediation strategies to real-world complex pollution sites; second, the technical principles are outdated, still limited by the traditional passivation understanding of "clay minerals passively adsorbing heavy metals," thus limiting remediation efficiency and stability; third, the selection of remediation agents is crude, relying solely on the inherent clay minerals of the site, making targeted remediation difficult. In view of this, this invention addresses the shortcomings of existing technologies in adapting to heavy metal-petroleum hydrocarbon complex pollution systems, outdated remediation principles, and insufficient remediation precision by proposing a precision remediation technology. This technology aims to overcome the limitations of existing technologies in the remediation of complex pollution and improve the remediation efficiency and stability of complex pollution sites in industrial clusters. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a clay mineral colloidal remediation agent and a method for in-situ fixation of heavy metal-petroleum hydrocarbon complex pollutants, in order to solve the technical problems of existing remediation technologies being outdated in principle, difficult to adapt to heavy metal-petroleum hydrocarbon complex pollution systems, and lacking in remediation precision.

[0006] To achieve the above-mentioned technical objectives, this application provides a clay mineral colloidal remediation agent, which is prepared from montmorillonite or kaolinite and is used to treat complex pollutants including heavy metals and petroleum hydrocarbons.

[0007] Furthermore, the clay mineral colloidal repair agent includes suspended mineral particles with a particle size of 100~300nm.

[0008] Furthermore, the clay mineral colloidal repair agent includes the following preparation steps:

[0009] Step S1: Ball milling montmorillonite or kaolinite to obtain a clay suspension containing mineral particles;

[0010] Step S2: Calculate the settling time of mineral particles of different sizes in the clay suspension, and collect the clay suspension containing mineral particles with a particle size of less than 1000 nm.

[0011] Step S3: The clay suspension containing mineral particles with a diameter of less than 1000 nm is subjected to sedimentation treatment. The supernatant is then subjected to ultrasonic dispersion and centrifugal separation operations in sequence. The resulting clear liquid is the clay mineral colloidal repair agent.

[0012] Furthermore, the particle size of montmorillonite or kaolinite is 50 mesh to 150 mesh.

[0013] Furthermore, during the ball milling process, the mass ratio of montmorillonite, grinding balls, and water is 1–3:1–3:1; or, the mass ratio of kaolinite, grinding balls, and water is 1–3:1–3:1.

[0014] Furthermore, during the ball milling process, clockwise grinding and counterclockwise grinding are performed alternately; the duration of clockwise grinding is 20 min to 40 min, the duration of counterclockwise grinding is 20 min to 40 min, and grinding is paused for 10 min to 20 min when switching grinding directions; the ball milling process includes at least one clockwise grinding and one counterclockwise grinding.

[0015] This application provides a method for in-situ immobilization of heavy metal-petroleum hydrocarbon complex pollutants, comprising the following steps:

[0016] Step S1: Conduct fixed-point sampling of soil and groundwater in the industrial cluster area to obtain soil spatial layout, groundwater hydrological characteristics, and spatial distribution data of primary clay minerals, petroleum hydrocarbons and heavy metals in soil and groundwater.

[0017] Step S2: Spatial interpolation method is used to characterize the spatial distribution characteristics of petroleum hydrocarbons and heavy metals in the soil and groundwater of the industrial cluster area and its surroundings, generating areal distribution data; based on the areal distribution data, a comprehensive spatial distribution analysis of heavy metals and petroleum hydrocarbons is conducted, with the polluted areas where heavy metals and petroleum hydrocarbons coexist as hotspot areas.

[0018] Step S3: Deploy pressurized injection wells in the hot spot area, and determine the depth of the injection wells and the position of the screen tubes according to the vertical distribution characteristics of the pollution plume. Inject clay mineral colloidal remediation agent into the hot spot area through the pressurized injection wells.

[0019] Step S4: Install monitoring wells downstream of the pressurized injection well and conduct regular monitoring of soil cores in the area of ​​the pressurized injection well and the monitoring well.

[0020] Furthermore, when the proportion of heavy metals and petroleum hydrocarbons in the hotspot area is greater than 1 / 50 mM / mg, a clay mineral colloidal repair agent prepared from kaolinite is selected; when the proportion of heavy metals and petroleum hydrocarbons in the hotspot area is less than or equal to 1 / 50 mM / mg, a clay mineral colloidal repair agent prepared from montmorillonite is selected.

[0021] Furthermore, it also includes a short-term effectiveness assessment step: 3 to 6 months after injecting clay mineral colloidal remediation agent into the hot spot area through pressurized injection wells, soil core samples from the pressurized injection well area are tested to analyze the changes in the available concentration of heavy metals and petroleum hydrocarbons in the soil core samples before and after the injection of clay mineral colloidal remediation agent. If the available concentration of heavy metals and petroleum hydrocarbons in the pressurized injection well area is significantly reduced, then the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0022] Furthermore, it also includes a long-term performance evaluation step: one year after the pressurized injection well injects clay mineral colloidal remediation agent into the hot spot area, soil cores from the pressurized injection well and monitoring well areas are tested every six months. If heavy metals are fixed in the pressurized injection well area and the vertical migration depth of heavy metals does not change significantly, then the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0023] In summary, this application provides a clay mineral colloidal remediation agent for treating complex pollutants including heavy metals and petroleum hydrocarbons. The clay mineral colloidal remediation agent is prepared from montmorillonite or kaolinite. This application induces controlled aggregation and deposition of heavy metals and petroleum hydrocarbons by injecting the clay mineral colloidal remediation agent into the complexly polluted area. Utilizing the interfacial interactions of the ternary system of "heavy metals-petroleum hydrocarbons-clay mineral colloids," long-term, stable, and in-situ fixation of the complex pollutants is achieved. Furthermore, the clay mineral colloidal remediation agent provided in this application is a natural clay mineral, an inherent component of the environmental medium. Its application will not damage soil structure or groundwater chemical balance, and there is no risk of secondary pollution. Its mechanism of action relies on physicochemical adsorption and aggregation effects, is not limited by microbial activity, and has a wide adaptability range to environmental conditions such as pH and salinity. It is an environmentally friendly and widely applicable green remediation material.

[0024] This application provides a method for in-situ fixation of heavy metal-petroleum hydrocarbon composite pollutants, comprising the following steps: sampling soil and groundwater at fixed points in an industrial cluster to obtain soil spatial layout, groundwater hydrological characteristics, and spatial distribution data of primary clay minerals, petroleum hydrocarbons, and heavy metals in the soil and groundwater; characterizing the spatial distribution characteristics of petroleum hydrocarbons and heavy metals in the industrial cluster and surrounding soil and groundwater using spatial interpolation methods to generate areal distribution data; conducting a comprehensive spatial distribution analysis of heavy metals and petroleum hydrocarbons based on the areal distribution data, identifying areas where both heavy metals and petroleum hydrocarbons coexist as hotspot areas; deploying pressurized injection wells in the hotspot areas, determining the depth of the injection wells and the location of the screen tubes based on the vertical distribution characteristics of the pollution plume, and injecting clay mineral colloidal remediation agents into the hotspot areas through the pressurized injection wells; and deploying monitoring wells downstream of the pressurized injection wells to periodically monitor soil cores in the areas of the pressurized injection wells and monitoring wells. The in-situ remediation method provided in this application can achieve precise in-situ treatment of areas with combined heavy metal and petroleum hydrocarbon pollution. It can effectively fix pollutants in place, ensuring that they do not migrate or spread in the long term, and significantly improve the stability and safety of pollution control.

[0025] Compared with existing technologies, the clay mineral colloidal remediation agent provided in this solution can effectively solve the dual pollution problem of heavy metals and petroleum hydrocarbons in the long term. It overcomes the shortcomings of traditional remediation technologies that are difficult to accurately adapt to the treatment needs of the two pollutants. Moreover, the raw materials of the remediation agent are readily available, the preparation process is simple, and the treatment cost is controllable, which has broad prospects for practical application. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Clay mineral colloidal repair agents prepared for kaolinite at different Pb 2+ -Effective hydrodynamic diameter under petroleum hydrocarbon ratio conditions;

[0028] Figure 2 Clay mineral colloidal repair agents prepared for kaolinite at different Pb 2+ -Average particle size under petroleum hydrocarbon ratio conditions;

[0029] Figure 3 Clay mineral colloidal repair agents prepared for kaolinite in different Cu 2+ Effective hydrodynamic diameter under the condition of petroleum hydrocarbon ratio;

[0030] Figure 4 Clay mineral colloidal repair agents prepared for kaolinite in different Cu 2+ Average particle size under the condition of petroleum hydrocarbon ratio;

[0031] Figure 5 Clay mineral colloidal repair agents prepared for kaolinite in different Zn 2+ Effective hydrodynamic diameter under the condition of petroleum hydrocarbon ratio;

[0032] Figure 6 Clay mineral colloidal repair agents prepared for kaolinite in different Zn 2+ Average particle size under the condition of petroleum hydrocarbon ratio;

[0033] Figure 7 Clay mineral colloidal remedial agents prepared for montmorillonite at different Pb 2+ Effective hydrodynamic diameter under the condition of petroleum hydrocarbon ratio;

[0034] Figure 8 Clay mineral colloidal remedial agents prepared for montmorillonite at different Pb 2+ Average particle size under the condition of petroleum hydrocarbon ratio;

[0035] Figure 9 Clay mineral colloidal repair agents prepared for montmorillonite in different Cu 2+ Effective hydrodynamic diameter under the condition of petroleum hydrocarbon ratio;

[0036] Figure 10 Clay mineral colloidal repair agents prepared for montmorillonite in different Cu2+ Average particle size under the condition of petroleum hydrocarbon ratio;

[0037] Figure 11 Clay mineral colloidal remedial agents prepared for montmorillonite in different Zn 2+ Effective hydrodynamic diameter under the condition of petroleum hydrocarbon ratio;

[0038] Figure 12 Clay mineral colloidal remedial agents prepared for montmorillonite in different Zn 2+ Average particle size under the condition of petroleum hydrocarbon ratio;

[0039] Figure 13 The flowchart shows the method for in-situ fixation of heavy metal-petroleum hydrocarbon complex pollutants provided in Example 3. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0041] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship shown, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] Unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0043] The raw materials used in this invention are not particularly restricted in their source; they can be purchased on the market or prepared using conventional methods known to those skilled in the art.

[0044] This application provides a clay mineral colloidal remediation agent, which is prepared from montmorillonite or kaolinite, and is used to treat complex pollutants including heavy metals and petroleum hydrocarbons.

[0045] It should be noted that in actual industrial cluster environments, petroleum hydrocarbons are a widespread co-polluting component. The introduction of petroleum hydrocarbons significantly alters the interfacial chemical environment of the pollution system, forming a ternary system of "heavy metals-petroleum hydrocarbons-clay minerals." The migration patterns, adsorption characteristics, and aggregation behavior of pollutants in this system differ significantly from those of traditional binary systems of "heavy metals-clay minerals" or "petroleum hydrocarbons-clay minerals." Within this ternary system, trace amounts of petroleum hydrocarbons can trigger a significant "hydrophobic bridging" effect, inducing the aggregation and deposition of colloids and pollutants, thereby achieving efficient in-situ retention of pollutants. It is noteworthy that different types of clay minerals (such as kaolinite and montmorillonite) exhibit drastically different environmental behaviors in the ternary system due to differences in their crystal structures: for example, kaolinite is prone to aggregation, while montmorillonite is more likely to maintain a stable colloidal state. Therefore, this application adopts colloids, which are traditionally considered to have migration risks, as a highly efficient pollutant fixation medium, and proposes a "ternary system to block migration" treatment system. Relying on the dual adsorption properties of clay mineral colloidal remediation agents for heavy metals and petroleum hydrocarbons, a more stable aggregate precipitate is formed to achieve the goal of "one agent, two fixations" for the treatment of composite pollutants.

[0046] It should be further explained that clay mineral colloidal remediation agents use natural clay minerals as their core component. Clay itself is an important part of the natural environmental medium, and its application will not disrupt soil structure or water chemical balance. Its mechanism of action is based on physicochemical adsorption and aggregation, is not limited by microbial activity, has a wide range of adaptability to environmental conditions such as pH and salinity, and can completely avoid the risk of secondary pollution.

[0047] In some embodiments, the clay mineral colloidal repair agent comprises suspended mineral particles with a particle size of 100-300 nm.

[0048] In some embodiments, when the proportion of heavy metals and petroleum hydrocarbons in the composite pollutants is greater than 1 / 50 mM / mg, a clay mineral colloidal remediation agent prepared from kaolinite is selected to treat the composite pollutants; when the proportion of heavy metals and petroleum hydrocarbons in the composite pollutants is less than or equal to 1 / 50 mM / mg, a clay mineral colloidal remediation agent prepared from montmorillonite is selected to treat the composite pollutants.

[0049] It should be noted that using the "threshold of heavy metal and petroleum hydrocarbon concentration ratio" as a key indicator can enable the scientific zoning of complex pollution areas: accurately dividing them into "agglomeration-promoting zones" and "stabilization zones," providing a quantitative basis for the precise selection and efficient application of clay mineral colloidal remediation agents.

[0050] In some embodiments, the clay mineral colloidal repair agent includes the following preparation steps:

[0051] Step S1: Ball milling montmorillonite or kaolinite to obtain a clay suspension containing mineral particles;

[0052] Step S2: Calculate the settling time of mineral particles of different sizes in the clay suspension, and collect the clay suspension containing mineral particles with a particle size of less than 1000 nm.

[0053] Step S3: The clay suspension containing mineral particles with a diameter of less than 1000 nm is subjected to sedimentation treatment. The supernatant is then subjected to ultrasonic dispersion and centrifugal separation operations in sequence. The resulting clear liquid is the clay mineral colloidal repair agent.

[0054] In some preferred embodiments, the particle size of montmorillonite or kaolinite is 50 mesh to 150 mesh.

[0055] In some preferred embodiments, during the ball milling process, the mass ratio of montmorillonite, grinding balls, and water is 1–3:1–3:1; or, the mass ratio of kaolinite, grinding balls, and water is 1–3:1–3:1.

[0056] In some preferred embodiments, during the ball milling process, clockwise grinding and counterclockwise grinding are performed alternately; wherein the duration of clockwise grinding is 20 min to 40 min and the duration of counterclockwise grinding is 20 min to 40 min, and grinding is paused for 10 min to 20 min when switching grinding directions; the ball milling process includes at least one clockwise grinding and one counterclockwise grinding.

[0057] This application provides a method for in-situ immobilization of heavy metal-petroleum hydrocarbon complex pollutants, including the following steps:

[0058] Step S1: Conduct fixed-point sampling of soil and groundwater in the industrial cluster area to obtain soil spatial layout, groundwater hydrological characteristics, and spatial distribution data of primary clay minerals, petroleum hydrocarbons and heavy metals in soil and groundwater.

[0059] Step S2: Spatial interpolation method is used to characterize the spatial distribution characteristics of petroleum hydrocarbons and heavy metals in the soil and groundwater of the industrial cluster area and its surroundings, generating areal distribution data; based on the areal distribution data, a comprehensive spatial distribution analysis of heavy metals and petroleum hydrocarbons is conducted, with the polluted areas where heavy metals and petroleum hydrocarbons coexist as hotspot areas.

[0060] Step S3: Deploy pressurized injection wells in the hot spot area, and determine the depth of the injection wells and the position of the screen tubes according to the vertical distribution characteristics of the pollution plume. Inject clay mineral colloidal remediation agent into the hot spot area through the pressurized injection wells.

[0061] Step S4: Install monitoring wells downstream of the pressurized injection well and conduct regular monitoring of soil cores in the area of ​​the pressurized injection well and the monitoring well.

[0062] In some embodiments, when the ratio of heavy metals and petroleum hydrocarbons in the hotspot area is greater than 1 / 50 mM / mg, a clay mineral colloidal remediation agent prepared with kaolinite is selected; when the ratio of heavy metals and petroleum hydrocarbons in the hotspot area is less than or equal to 1 / 50 mM / mg, a clay mineral colloidal remediation agent prepared with montmorillonite is selected.

[0063] It should be noted that by deploying monitoring wells downstream of the pressurized injection well, it is possible to monitor whether pollutants migrate in the groundwater. When the effective content of heavy metals and petroleum hydrocarbons in the monitoring well area does not show a significant increase, it indicates that the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0064] In some embodiments, a short-term performance evaluation step is also included: 3 to 6 months after injecting clay mineral colloidal remediation agent into the hot spot area through pressurized injection wells, soil cores of the pressurized injection well area are tested to analyze the changes in the available concentration of heavy metals and petroleum hydrocarbons in the soil cores before and after the injection of clay mineral colloidal remediation agent. If the available concentration of heavy metals and petroleum hydrocarbons in the pressurized injection well area are significantly reduced, then the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0065] In some preferred embodiments, the particle size of colloidal-contaminant aggregates formed by clay mineral colloidal remediation agent with heavy metals and petroleum hydrocarbons in the pressurized injection well area can also be monitored. If large-area formation of colloidal-contaminant aggregates is detected, the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0066] In some embodiments, a long-term performance evaluation step is also included: one year after the pressurized injection well injects clay mineral colloidal remediation agent into the hot spot area, soil cores of the pressurized injection well and monitoring well area are tested every six months. If heavy metals are fixed in the pressurized injection well area and the vertical migration depth of heavy metals does not change significantly, then the clay mineral colloidal remediation agent has a good adsorption effect on heavy metals and petroleum hydrocarbons.

[0067] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0068] Example 1

[0069] This embodiment provides a clay mineral colloidal repair agent, which is prepared from montmorillonite or kaolinite. The specific steps are as follows:

[0070] Step S1: Commercially available high-purity montmorillonite or kaolinite powder (100 mesh) is mixed with grinding balls and pure water at a mass ratio of 2:1:1, and then ground in a ball mill for 1440 min to obtain a clay suspension containing mineral particles. The ball milling parameters are set as follows: rotate clockwise at 300 rpm for 30 min, stop for 20 min, and then rotate counterclockwise for 30 min.

[0071] Step S2: After ball milling, the clay suspension is subjected to sedimentation treatment, and the sedimentation time of mineral particles with a particle size of more than 1000 nm is calculated according to Stokes' law. Then, based on the sedimentation time of mineral particles (more than 1000 nm), the clay suspension containing mineral particles with a particle size of less than 1000 nm is collected and subjected to sedimentation treatment to obtain the supernatant.

[0072] Step S3: The supernatant is ultrasonically dispersed using an acoustic cell disruptor, and then the supernatant is centrifuged using a high-speed centrifuge. The resulting clear liquid is the clay mineral colloidal repair agent. The clay mineral colloidal repair agent is transferred to a container, and the particle size of the mineral particles in the clay mineral colloidal repair agent is measured to be 200 nm using a multi-angle particle size and high-sensitivity Zeta potential analyzer.

[0073] Example 2

[0074] This embodiment provides an application of a clay mineral colloidal remediation agent for treating a heavy metal-petroleum hydrocarbon complex pollution system. The treatment steps are as follows:

[0075] Step S1, prepare petroleum hydrocarbon dispersion solution: add excess 0# diesel oil (purchased from China National Petroleum Corporation) to 4L of deionized water; use a magnetic stirrer to fully disperse and stir at 900rpm for 24h, then let stand for 24h to remove the upper floating oil to obtain petroleum hydrocarbon dispersion solution.

[0076] Step S2: Constructing a heavy metal-petroleum hydrocarbon composite pollutant system containing clay mineral colloidal remediation agent: Add 1 mL of clay mineral colloidal remediation agent, different metal solutions with sodium nitrate as the background metal, and different volumes of petroleum hydrocarbon dispersion solution to multiple centrifuge tubes to obtain multiple heavy metal-petroleum hydrocarbon composite pollutant systems containing clay mineral colloidal remediation agent. These multiple heavy metal-petroleum hydrocarbon composite pollutant systems include metal ions, clay mineral colloidal remediation agent, and petroleum hydrocarbons; wherein the metal ion concentration is 0.1 mmol·L⁻¹. -1 Pb 2+ 0.2 mmol·L -1 Cu 2+ Or 0.2 mmol·L -1 Zn 2+ The mass concentration of the clay mineral colloidal repair agent is 100 mg·L⁻¹.-1 The concentration of petroleum hydrocarbons is 2 mg·L⁻¹. -1 5 mg·L -1 10 mg·L -1 20 mg·L -1 Or 25 mg·L -1 ;

[0077] Step S3: Mix the heavy metal-petroleum hydrocarbon complex pollution system containing clay mineral colloidal remediation agent for 2 minutes to form a colloidal product.

[0078] Test: 1.5–2 mL of the mixed heavy metal-petroleum hydrocarbon complex pollution system containing clay mineral colloidal remediation agent was placed in the sample cell. The effective hydrodynamic diameter (nm) of the colloidal product was determined using a multi-angle particle size analyzer and a high-sensitivity Zeta potential analyzer. The test results are shown in [reference needed]. Figures 1-12 .

[0079] from Figures 1-6 It is known that clay mineral colloidal remediation agents prepared from kaolinite powder form colloidal products with larger particle size and more significant agglomeration effect in heavy metal-petroleum hydrocarbon complex pollutant systems with low concentrations of petroleum hydrocarbons, effectively blocking the migration and diffusion of heavy metal and petroleum hydrocarbon complex pollutants in soil or groundwater. Figures 7-12 It is known that clay mineral colloidal remediation agents prepared with montmorillonite powder can fix heavy metals in complex pollution systems through interlayer adsorption. Their strong hydrophilic surface properties can resist interference from high concentrations of petroleum hydrocarbons, maintain the stability of colloidal products, and thus achieve long-term, slow passivation of pollutants. Based on these characteristics, it is concluded that in pollution areas with a high ratio of heavy metals to petroleum hydrocarbons (i.e., a ratio greater than 1 / 50 mM / mg), clay mineral colloidal remediation agents prepared with kaolinite should be selected; while in pollution areas with a low ratio of heavy metals to petroleum hydrocarbons (i.e., a ratio less than or equal to 1 / 50 mM / mg), clay mineral colloidal remediation agents prepared with montmorillonite should be selected.

[0080] Example 3

[0081] See Figure 13 This embodiment provides a method for in-situ immobilization of heavy metal-petroleum hydrocarbon complex pollutants, including the following steps:

[0082] Step S1, Data Acquisition: Collect soil and groundwater data from the industrial cluster area to obtain soil spatial layout, groundwater hydrological characteristics (including groundwater level, rainfall, topography, and groundwater flow characteristics), and the distribution of primary clay minerals, petroleum hydrocarbons, and heavy metals in the soil and groundwater.

[0083] Step S2: Construct a three-dimensional geological model and delineate hotspot areas; determine typical heavy metals (including but not limited to Pb). 2+ Cu 2+ Zn 2+ The total amount, available content, and petroleum hydrocarbon content of heavy metals and petroleum hydrocarbons were determined to clarify their spatial distribution in industrial clusters. Spatial interpolation methods such as Kriging were used to characterize the spatial distribution of characteristic pollutants in soil and groundwater within and outside industrial clusters, obtaining corresponding areal data. Grounder Modeling Systems and Finite Elements Subsurface FLOW system software were used to conduct a comprehensive spatial distribution analysis of heavy metals and petroleum hydrocarbons in soil and groundwater, and areas where both heavy metals and petroleum hydrocarbons coexist were designated as hotspot areas. The specific operation of using the Finite Element Subsurface FLOW System software for pollutant migration numerical modeling is as follows:

[0084] Step S21, Construction of hydrogeological conceptual model;

[0085] Model region scope and boundary conditions generalization: The model region is determined based on geological structures, topographic watersheds, rivers, lakes, or artificially defined boundaries; at the same time, boundary attributes such as head boundaries, flow boundaries, and impermeable boundaries are clearly defined.

[0086] Aquifer system structure generalization: Using a three-dimensional model, combined with data from boreholes and geophysical exploration to determine the medium type, construct the spatial distribution morphology of the aquifer and the weakly permeable layer (impermeable layer), and generate the elevation surfaces of the top and bottom plates of each layer;

[0087] Preliminary setting of hydrogeological parameters: Collect and analyze existing test data such as pumping tests and seepage tests, and set initial hydrogeological parameters for different lithological units, including hydraulic conductivity, water storage coefficient, porosity, and dispersion.

[0088] Step S22, model discretization;

[0089] Spatial subdivision: Fine subdivision is performed in two directions: horizontal and vertical. Horizontally, based on geological maps and hydrogeological survey data, the assessment area is divided into parallel grid cells to reflect stratigraphic continuity and the dominant direction of water flow. Vertically, the grid cell height is determined by considering stratigraphic thickness, properties (including the distribution of different aquifers and weakly permeable layers), and the vertical distribution characteristics of pollutant migration. The finite element method is used to solve the groundwater flow and solute transport problems.

[0090] Time stepping: Using "days" as the time step to ensure the model accurately captures key hydrogeological dynamics of the groundwater system;

[0091] Initial conditions are set: a certain moment in the target area is selected as the initial moment of the simulation, and the aquifer head and the initial concentration of groundwater pollutants at that moment are determined;

[0092] Boundary condition assignment: Define the boundary attributes of the three-dimensional geological model, select boundary types such as recharge boundary, discharge boundary, zero flux boundary, constant head boundary, and constant flow boundary on the delineated boundary, and complete the assignment;

[0093] Parameter optimization: Parameters were set by combining hydrogeological maps and indoor test data. By comparing the calculated water level with the observed water level in the field, the model parameters were adjusted and optimized to ensure accurate simulation of the hydrogeological characteristics of the assessment area.

[0094] Step S23, Pollutant Migration Simulation and Model Correction: Identify key factors affecting pollutant distribution, combine convection dispersion equations and chemical reaction equations to simulate the geochemical changes and migration paths of pollutants in soil and groundwater; for different stratigraphic hydrogeological conditions, conduct in-depth research on the chemical transport mechanism at the soil-groundwater interface, and establish a characteristic pollutant migration model; finally, through multi-media interface interaction research, Kalman filtering technology and supercomputing technology, parameter correction is performed to improve the accuracy and reliability of the model.

[0095] Step S3, deploy pressurized injection wells: precisely deploy a network of pressurized injection wells in the hotspot area; wherein, the depth of the pressurized injection wells and the position of the screen tubes are determined according to the vertical distribution characteristics of the contamination plume;

[0096] Step S4, Precise Injection of Remediation Agent: Through the deployed pressurized injection wells, the prepared clay mineral colloidal remediation agent is precisely injected into the hot spot area: For "polluted areas with a high ratio of heavy metals to petroleum hydrocarbons", "clay mineral colloidal remediation agent prepared with kaolinite" is selected; for "polluted areas with a low ratio of heavy metals to petroleum hydrocarbons" or areas with high background salinity, "clay mineral colloidal remediation agent prepared with montmorillonite" is selected.

[0097] Step S5, Dynamic monitoring of the injection process: A monitoring well is set up downstream of the pressurized injection well. Soil core samples are collected periodically from the pressurized injection well area and the monitoring well area during the injection process. By monitoring the changes in the effective concentration of heavy metals, petroleum hydrocarbons, and the concentration and particle size of colloids, it is determined whether the clay mineral colloidal remediation agent is working as expected in the target area. If any abnormality is found, the injection parameters are dynamically adjusted.

[0098] Step S6: Performance evaluation and long-term stability verification;

[0099] Short-term efficacy assessment: 3–6 months after injecting clay mineral colloidal remediation agent into the hotspot area via pressurized injection wells, samples were collected using the sampling method described in step S5. Changes in the effective concentrations of heavy metals and petroleum hydrocarbons in soil cores from the pressurized injection well area and the monitoring well area were compared before and after remediation. The results showed a significant decrease in the effective concentrations of heavy metals and petroleum hydrocarbons in the pressurized injection well area, while no significant changes were observed in the monitoring well area. Simultaneously, the samples collected from the pressurized injection well area were analyzed using an asymmetric field flowmeter coupled with inductively coupled plasma mass spectrometry (AF4-ICP-MS). The corresponding spectra showed a significant enhancement of signal peaks in the large particle size range, directly demonstrating the successful formation of colloidal-pollutant aggregates and indicating that the remediation achieved the expected results.

[0100] Long-term stability verification (1-2 years post-remediation): For 1-2 years following the injection of clay mineral colloidal remediation agent into the hotspot area via pressurized injection wells, regular monitoring was conducted every six months to assess the long-term effectiveness of the remediation project. Stability was verified through sedimentary profile analysis: Soil cores were collected from the pressurized injection well and monitoring well areas, ultrasonically dissolved in a 1 mM NaNO3 solution, and the amount of heavy metals fixed in the soil at different depths was determined. Monitoring results showed that a large amount of heavy metals were fixed in the pressurized injection well area, and the depth of their vertical downward migration did not increase significantly over the long term, indicating that the remediation project was stable and effective in the long term.

[0101] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A clay mineral colloid restorer characterized by, The clay mineral colloid remediation agent is prepared from montmorillonite or kaolinite and is used for treating composite pollutants including heavy metals and petroleum hydrocarbons.

2. The clay mineral colloid restorer according to claim 1, characterized in that, The clay mineral colloid remediation agent includes suspended mineral particles with a particle size of 100-300 nm.

3. The clay mineral colloid restorer according to claim 1, characterized in that, The clay mineral colloid remediation agent includes the following preparation steps: Step S1, ball milling treatment of montmorillonite or kaolinite to obtain a clay suspension containing mineral particles; Step S2, calculation of the settling time of mineral particles with different particle sizes in the clay suspension, and collection of the clay suspension containing mineral particles with a particle size less than 1000 nm; Step S3, settling treatment of the clay suspension containing mineral particles with a particle size less than 1000 nm, and ultrasonic dispersion and centrifugal separation of the supernatant in sequence to obtain the clay mineral colloid remediation agent.

4. The clay mineral colloid restorer according to claim 3, characterized in that, The particle size of the montmorillonite or the kaolinite is 50-150 mesh.

5. The clay mineral colloid restorer according to claim 3, characterized in that, In the ball milling process, the mass ratio of montmorillonite, grinding balls and water is 1-3:1-3:1; or, the mass ratio of kaolinite, grinding balls and water is 1-3:1-3:

1.

6. The clay mineral colloid restorer according to claim 3, characterized in that, In the ball milling process, clockwise milling and counterclockwise milling are alternately performed; wherein, the duration of clockwise milling is 20-40 min, the duration of counterclockwise milling is 20-40 min, and the milling is paused for 10-20 min when switching the milling direction; the ball milling process includes at least one clockwise milling and one counterclockwise milling.

7. A method for in-situ immobilization of heavy metal-petroleum hydrocarbon complex contaminants, characterized in that, The method includes the following steps: Step S1, fixed-point sampling of the soil and groundwater in the industrial cluster area to obtain the spatial layout of the soil, the hydrological characteristics of the groundwater, and the spatial distribution data of the native clay minerals, petroleum hydrocarbons and heavy metals in the soil and groundwater; Step S2, use of a spatial interpolation method to represent the spatial distribution characteristics of the petroleum hydrocarbons and heavy metals in the soil and groundwater in the industrial cluster area and the surrounding area to generate areal distribution data; based on the areal distribution data, comprehensive analysis is performed on the spatial distribution of the heavy metals and petroleum hydrocarbons, and the pollution area where the heavy metals and petroleum hydrocarbons exist simultaneously is taken as a hotspot area; Step S3, arrangement of a pressurized injection well in the hotspot area, determination of the depth and screen pipe position of the injection well according to the vertical distribution characteristics of the pollution plume, and injection of the clay mineral colloid remediation agent of any one of claims 1-6 into the hotspot area through the pressurized injection well; Step S4, arrangement of a monitoring well downstream of the pressurized injection well, and periodic monitoring of the soil core in the area of the pressurized injection well and the monitoring well.

8. The method for in-situ fixation of heavy metal-petroleum hydrocarbon composite pollutants according to claim 7, characterized in that: when the ratio of heavy metals to petroleum hydrocarbons in the hotspot area is greater than 1 / 50 mM / mg, the clay mineral colloid remediation agent prepared from kaolinite is selected; when the ratio of heavy metals to petroleum hydrocarbons in the hotspot area is less than or equal to 1 / 50 mM / mg, the clay mineral colloid remediation agent prepared from montmorillonite is selected.

9. The method of in-situ fixation of heavy metal-petroleum hydrocarbon complex contaminants as claimed in claim 7, wherein, It also includes a short-term effectiveness evaluation step: 3-6 months after the clay mineral colloid remediation agent is injected into the hot spot area by the pressurized injection well, the soil core in the area of the pressurized injection well is tested, and the changes in the effective state concentration of heavy metals and the concentration of petroleum hydrocarbons in the soil core before and after the injection of the clay mineral colloid remediation agent are analyzed. If the effective state concentration of heavy metals and the concentration of petroleum hydrocarbons in the area of the pressurized injection well are significantly reduced, the clay mineral colloid remediation agent has good adsorption effect on heavy metals and petroleum hydrocarbons.

10. The method of in-situ fixation of heavy metal-petroleum hydrocarbon complex contaminants as claimed in claim 7, wherein, It also includes a long-term effectiveness evaluation step: one year after the clay mineral colloid remediation agent is injected into the hot spot area by the pressurized injection well, the soil core in the area of the pressurized injection well and the monitoring well is tested every half year. If the heavy metals are fixed in the area of the pressurized injection well and the vertical downward migration depth of the heavy metals does not change significantly, the clay mineral colloid remediation agent has good adsorption effect on heavy metals and petroleum hydrocarbons.

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