Simulated experimental device for migration of organic pollutants in clay-aquifer

Abstract

This invention relates to the field of groundwater pollution migration and behavior simulation technology, specifically to a simulation experimental device for the migration of organic pollutants in clay-aquifers. The device includes a chip body, which uses a transparent quartz glass microporous medium chip as a carrier. Inside the chip, an upper clay layer simulation cavity and a lower aquifer sand layer simulation cavity are constructed. Combined with controllable compaction loading and a detachable interface isolation structure, the device enables intuitive observation and repeatable experimental research on the migration, retention and release processes of the clay-aquifer micro-interface.

Description

Technical Field

[0001] This invention relates to the field of groundwater pollution migration and behavior simulation technology, specifically to a simulation experimental device for the migration of organic pollutants in clay-aquifers. Background Technology

[0002] With the acceleration of industrialization and urbanization, the number of legacy industrial sites and contaminated sites has increased, and soil and groundwater in some areas have been contaminated by organic pollutants, especially non-aqueous liquids (NAPLs). Among them, heavy non-aqueous liquids (DNAPLs) with a density greater than water (such as chlorinated hydrocarbons) are highly toxic, have complex migration pathways, and long residence times, and have become a key focus and challenge in groundwater pollution control.

[0003] In actual underground media, DNAPL migration is often influenced by the interfacial structure between clay / silty layers and aquifers, easily leading to interfacial retention, pooling, re-migration, and slow release, directly affecting the spread of contaminant plumes and remediation effectiveness. However, our understanding of the migration mechanism of DNAPL at the clay-aquifer micro-interface remains limited, especially regarding the changes in interfacial contact state, pore structure evolution, and their impact on migration channels and retention morphologies under clay compaction conditions, for which intuitive and controllable experimental methods are lacking.

[0004] Existing studies mostly employ columnar seepage, sandboxes, or large-scale physical model devices, which generally suffer from problems such as large volume, high material consumption, and poor or no internal visibility, making it difficult to observe the distribution of pollutants and interfacial processes in porous media in real time at the microscale. At the same time, traditional devices often simulate aquifers by filling sand or treat the interface with integral clay blocks or artificial layers, making it difficult to stably construct the direct contact micro-interface between the clay layer and the aquifer and its repeatable conditions.

[0005] In recent years, microfluidic technology has been used in the study of seepage and mass transfer in porous media. However, most existing microfluidic chips are made of polymer materials, which are not resistant to organic solvents such as chlorinated hydrocarbons. Moreover, most of them have homogeneous or simplified pore structures, making it difficult to simulate heterogeneous seepage channels in aquifers. In addition, many devices lack the ability to simulate and control the clay compaction process, making it difficult to apply adjustable normal pressure to clay and to achieve temporary interfacial isolation and post-compaction reconnection during the compaction stage. Summary of the Invention

[0006] To address the shortcomings of existing experimental devices for the migration behavior of organic pollutants in groundwater, such as large size, high material consumption, and invisible internal structure, making it difficult to realistically construct the direct contact interface between clay layers and aquifers at the microscopic scale, and the general lack of controllable simulation of clay compaction conditions, this invention provides a simulation experimental device for the migration of organic pollutants in clay-aquifers. This device uses a transparent quartz glass microporous medium chip as a carrier, constructing an upper clay layer simulation cavity and a lower aquifer sand layer simulation cavity inside the chip. Combined with controllable compaction loading and a detachable interface isolation structure, it enables intuitive observation and repeatable experimental research on the migration, retention, and release processes of the clay-aquifer micro-interface.

[0007] The technical solution adopted by this invention to solve its technical problem is: a simulation experimental device for the migration of organic pollutants in clay-aquifer, including a chip body made of transparent quartz glass material, which is a closed thin structure with an overall thickness of 1-2 mm to meet the need for real-time observation of the migration process inside the chip under a microscope. The transparent quartz glass material has good resistance to organic solvent corrosion and can withstand the erosion of organic pollutants such as chlorinated hydrocarbons for a long time, ensuring the structural stability and optical transparency of the experimental device in repeated use. The chip body is assembled from a base plate and a top cover plate to form a closed transparent thin sheet structure. The chip body has a connected clay layer simulation cavity and an aquifer sand layer simulation cavity inside. The clay layer simulation cavity is located in the upper half of the chip body and is used to fill the clay medium. The cavity is opened and closed by a detachable top cover, which facilitates the filling, compaction and removal of the clay medium after the experiment. The clay medium can be a slurry made of bentonite powder and deionized water, which is compacted and solidified to form a stable clay layer, used to simulate a low-permeability clay lens or water-proof layer in the underground environment. The water-bearing sand layer simulation cavity is located in the lower half of the chip body and is used to simulate the seepage environment of underground aquifers. One end of the water-bearing sand layer simulation cavity is connected to the outside of the chip body and is used for fluid discharge. It is integrally formed in a quartz glass substrate through micro-machining or etching process, without the use of sand filling method, thereby improving repeatability and facilitating microscopic observation. The other end of the water-bearing sand layer simulation cavity is connected to an underground water injection channel and an organic pollutant injection channel for fluid injection, which are used to connect to external pipelines and automatic injection pumps. The upper part of the clay layer simulation cavity is equipped with a compaction component for compacting the clay medium. A partition that can be pulled out from the side of the chip body is provided between the clay layer simulation cavity and the water-bearing sand layer simulation cavity. The partition isolates the clay layer simulation cavity and the water-bearing sand layer simulation cavity during the compaction of the clay medium by the compaction component, and is pulled out after the compaction component is completed to restore the connection between the clay layer simulation cavity and the water-bearing sand layer simulation cavity. The partition is a thin sheet structure. During the clay compaction stage, the partition is inserted into the insertion hole to temporarily isolate the clay layer simulation cavity and the water-bearing sand layer simulation cavity to prevent clay from entering the water-bearing sand layer simulation cavity and the seepage channel during the compaction process. After compaction is completed, the partition is pulled out from the insertion hole to restore the vertical direct connection between the clay layer simulation cavity and the water-bearing sand layer simulation cavity, thereby forming a stable and reconstructable clay-aquifer interface.

[0008] Preferably, the base plate and the top cover plate are fitted together. The clay layer simulation cavity and the water-bearing sand layer simulation cavity are both opened on the base plate and located on the side where the base plate and the top cover plate are fitted together. The base plate and the top cover plate are fixed with main body fixing screws. The main body fixing screws achieve a reliable fixed connection, ensuring transparency and visibility while achieving reliable sealing, effectively preventing fluid leakage during the experiment.

[0009] Preferably, the compaction assembly includes a compaction plate and compaction screws. The compaction plate is horizontally positioned near the top of the clay layer simulation cavity, and the width of the compaction plate is adapted to the width of the clay layer simulation cavity. Several compaction screws are threaded onto the top of the base plate, and the bottom of several compaction screws penetrates the base plate into the clay layer simulation cavity to apply pressure to the compaction plate. An adjustable normal load can be applied to the compaction plate by rotation adjustment to simulate the state of clay layer being compacted under pressure in actual strata.

[0010] Preferably, the compaction assembly further includes an elastic diaphragm, which is disposed between the compaction plate and the clay medium to achieve flexible pressure equalization and sealing isolation, avoid local stress concentration that leads to uneven compaction of the clay medium, and at the same time play a sealing isolation role to prevent fluid or fine clay particles from overflowing upwards during the compaction process.

[0011] Preferably, a transverse insertion hole is provided on the side of the upper cover plate at the middle of the clay layer simulation cavity and the water-bearing sand layer simulation cavity. The cross-section of the insertion hole is adapted to the cross-section of the partition plate, and the partition plate is pulled out through the insertion hole.

[0012] Preferably, it also includes a cover glass slide, which is attached and fixed to the side of the upper cover plate away from the base plate of the chip body after the partition is removed, so as to form a microscopic observation window and enhance the sealing and visualization effect. The cover glass slide and the upper cover plate are fixed with glass slide sealing screws to form a reliable sealing connection to prevent fluid leakage and the release of volatile organic pollutants during the experiment.

[0013] Preferably, the chip body has a groundwater injection interface connected to a groundwater injection channel, an organic pollutant injection interface connected to an organic pollutant injection channel, and a pollutant outflow interface connected to a seepage channel at both ends. Both the groundwater injection interface and the organic pollutant injection interface are suitable for connection to an external automatic injection pump or pipeline system to achieve separate injection of groundwater and organic pollutants. By connecting a high-precision automatic injection pump or peristaltic pump to the corresponding interface, the groundwater flow rate and the injection concentration and rate of organic pollutants can be controlled separately, enabling comparative experiments under different hydraulic gradients and pollution loads.

[0014] Preferably, the seepage channels are porous network structures with pore sizes distributed at different scales to reflect the heterogeneous porosity characteristics of the aquifer. These seepage channels are formed into porous microchannel structures within the chip substrate through microfabrication or etching processes, serving as an equivalent simulation of the aquifer's pore structure and seepage environment.

[0015] Preferably, the chip body is made of transparent quartz glass to meet the requirements of resistance to organic pollutants and organic solvent corrosion, as well as to meet the requirements of microscopic observation.

[0016] The beneficial effects of this invention are: (1) In this invention, the simulation experimental device for the migration of organic pollutants in clay-aquifers uses a chip body as a carrier, which is assembled from a base plate and a top cover plate to form a closed transparent sheet structure, and the whole is at the microfluidic chip scale. Compared with traditional columnar seepage, sand box or large physical model devices, this device has a compact structure, which greatly reduces the amount of clay medium, sand layer material and experimental fluid used, significantly reduces the consumption of experimental materials and costs, and facilitates repeated experimental research under normal laboratory conditions.

[0017] (2) In this invention, the main body of the chip of the simulation experimental device for the migration of organic pollutants in clay-aquifer is made of transparent quartz glass. With the cover glass slide forming a microscopic observation window, researchers can conduct real-time, in-situ observations of the migration process of organic pollutants inside the clay layer simulation cavity and the aquifer sand layer simulation cavity under a microscope. This design overcomes the defects of existing experimental devices that are not visible or have poor visibility, and provides an effective technical means for intuitively revealing the migration, retention and release mechanisms of organic pollutants at the clay-aquifer micro-interface.

[0018] (3) In this invention, the simulation experimental device for the migration of organic pollutants in clay-aquifer has a compaction component set on the upper part of the clay layer simulation cavity, including a compaction plate, a compaction screw, and an elastic diaphragm. By adjusting the compaction screw, an adjustable normal pressure is applied to the compaction plate, and after being flexibly uniformly pressed by the elastic diaphragm, it is transmitted to the clay medium, realizing precise control of the compaction degree of the clay medium. This makes up for the deficiency of the existing technology in the lack of controllable simulation of clay compaction conditions, and facilitates the systematic study of the differences in the migration behavior of organic pollutants under different compaction states. In addition, a clay layer simulation cavity and an aquifer sand layer simulation cavity are set vertically inside the chip body, and the two cavities are temporarily isolated and restored to communication through a partition that can be pulled out from the side. After compaction is completed, the partition is pulled out, and the clay layer simulation cavity and the aquifer sand layer simulation cavity are directly connected and in contact, which truly simulates the natural contact state between the clay layer and the aquifer in the actual strata, and solves the problem that the existing technology is difficult to stably construct the clay-aquifer direct contact micro-interface. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This is a schematic diagram of the assembly structure of the chip body after the separator is removed and the cover glass plate is assembled.

[0021] Figure 2 This is a schematic diagram of the main structure of the chip of the present invention.

[0022] Figure 3 This is a schematic diagram of the base plate structure of the present invention.

[0023] Figure 4 This is a schematic diagram of the upper cover plate structure of the present invention.

[0024] Figure 5 Microscopic images of experimental results for an example.

[0025] In the diagram: 1. Chip body; 2. Base plate; 3. Top cover plate; 4. Cover plate slide; 5. Clay layer simulated cavity; 6. Water-bearing sand layer simulated cavity; 7. Partition plate; 8. Compactor plate; 9. Elastic diaphragm; 10. Compactor screw; 11. Groundwater injection channel; 12. Groundwater injection interface; 13. Organic pollutant injection channel; 14. Organic pollutant injection interface; 15. Seepage channel; 16. Pollutant outflow interface; 17. Insertion hole; 18. Body fixing screw; 19. Slide sealing screw. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0027] like Figures 1-4As shown, the simulation experimental device for the migration of organic pollutants in clay-aquifers according to the present invention includes a chip body 1. The chip body 1 is assembled from a base plate 2 and an upper cover plate 3 to form a closed transparent sheet structure. The chip body 1 has a connected clay layer simulation cavity 5 and an aquifer sand layer simulation cavity 6 inside.

[0028] The chip body 1 is made of transparent quartz glass with an overall thickness of 1-2 mm to meet the requirements of resistance to organic pollutants, organic solvent corrosion, and microscopic observation. The base plate 2 and the top cover plate 3 are fitted together. The clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6 are both opened on the base plate 2 and located on the side where the base plate 2 and the top cover plate 3 are fitted together. The base plate 2 and the top cover plate 3 are fixed together by the main body fixing screws 18.

[0029] The clay layer simulation cavity 5 is located in the upper half of the chip body 1 and is used to fill the clay medium; the water-bearing sand layer simulation cavity 6 is located in the lower half of the chip body 1. One end of the water-bearing sand layer simulation cavity 6 is connected to a seepage channel 15 that communicates with the outside of the chip body 1 for fluid discharge; the other end of the water-bearing sand layer simulation cavity 6 is connected to a groundwater injection channel 11 and an organic pollutant injection channel 13 for fluid injection. The seepage channel 15 has a porous network structure with pore sizes distributed at different scales to equivalently simulate the heterogeneous characteristics of the aquifer pore structure.

[0030] The upper part of the clay layer simulation cavity 5 is equipped with a compaction assembly for compacting the clay medium, including a compaction plate 8, compaction screws 10, and an elastic diaphragm 9. The compaction plate 8 is horizontally positioned inside the clay layer simulation cavity 5 near the top, and its width is adapted to the width of the clay layer simulation cavity 5. Several compaction screws 10 are threaded onto the top of the base plate 2, and their bottoms penetrate the base plate 2 into the clay layer simulation cavity 5 to apply pressure to the compaction plate 8. The elastic diaphragm 9 is positioned between the compaction plate 8 and the clay medium to achieve flexible pressure equalization and sealing isolation.

[0031] A partition 7, removable from the side of the chip body 1, is provided between the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6. A transverse insertion hole 17 is provided on the side of the upper cover plate 3, corresponding to the middle of the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6. The cross-section of the insertion hole 17 is adapted to the cross-section of the partition 7, allowing the partition 7 to be removed. The partition 7 isolates the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6 during the compaction of the clay medium by the compaction component, and is removed after the compaction component completes, restoring communication between the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6.

[0032] After the partition 7 is removed, the cover glass slide 4 is attached and fixed to the side of the upper cover plate 3 away from the base plate 2 of the chip body 1 to form a microscopic observation window. The cover glass slide 4 and the upper cover plate 3 are fixed by the glass slide sealing screw 19.

[0033] The chip body 1 has a groundwater injection interface 12 connected to the groundwater injection channel 11, an organic pollutant injection interface 14 connected to the organic pollutant injection channel 13, and a pollutant outflow interface 16 connected to the seepage channel 15 at both ends. The groundwater injection interface 12 and the organic pollutant injection interface 14 are both suitable for connection to an external automatic injection pump or pipeline system.

[0034] Example Experimental principle: This method is based on the principle of combining microfluidic technology with high-resolution fluorescence microscopy. The core element is the construction of a microscopic visualization reaction chamber (or flow chamber) simulating a heterogeneous underground environment. A bentonite layer is pre-placed in a specific area of ​​this reaction chamber to simulate a low-permeability clay lens or impermeable layer in the underground environment. Prepared chlorobenzene stained with the fluorescent dye Nile Red (simulating groundwater contaminated with DNAPL) is injected into a fluid supply device, which is connected to the injection port of the microscopic visualization reaction chamber via a high-precision automatic injection pump.

[0035] Fluid enters the reaction tank under driving force, causing organic chlorobenzene to displace groundwater and fill the aquifer. Groundwater is then injected to simulate the migration of organic chlorobenzene at the bentonite-sand interface under groundwater flow conditions. Nile red dye emits fluorescence under fluorescence excitation. The microscopically visualized reaction tank is placed on a high-powered microscope stage equipped with high-speed imaging. The working principle utilizes an optical magnification system and fluorescence excitation to capture the instantaneous distribution of chlorobenzene at the sand-clay interface and its subsequent dynamic behavior in real time and in situ. This includes observing the aggregation and accumulation of chlorobenzene at the interface, the three-phase distribution of groundwater, chlorobenzene, and air, the deformation of chlorobenzene under capillary forces, changes in the wetting contact angle, the formation and migration of residual chlorobenzene under groundwater flushing, and whether it invades the bentonite pores and throats when the critical displacement pressure is reached.

[0036] By controlling the groundwater injection rate, changing the aqueous phase chemical conditions (such as ion species or ion concentration), or adjusting the density of the bentonite layer, this device is used to explore the transport mechanism of multiphase fluids at the micro-interface of porous media, and to quantitatively analyze the effects of groundwater flow rate, pollutant properties, and remediation agent concentration on the migration and residue of DNAPL pollutants at the sand-clay interface.

[0037] Experimental preparation: Clay medium: High-purity bentonite powder and deionized water are mixed in a certain proportion to form a slurry. Simulated pollutant: Analytical grade chlorobenzene, stained with an oil-based fluorescent dye (such as Nile Red). The stained chlorobenzene appears red, and turns golden yellow under green fluorescence excitation, facilitating microscopic observation. Experimental water: Deionized water.

[0038] Experimental steps Step 1: Insert the partition 7 into the chip body 1 along the insertion hole 17 to temporarily isolate the clay layer simulation cavity 5 from the water-bearing sand layer simulation cavity 6. Carefully inject bentonite slurry into the clay layer simulation cavity 5. This step is performed with the upper cover plate 3 and the bottom plate 2 of the chip body 1 separated. After the clay layer simulation cavity 5 is filled, reassemble and fix the upper cover plate 3 and the bottom plate 2. Step 2: Tighten the compaction screw 10. Normal pressure is applied to the clay medium through the compaction plate 8 and the elastic diaphragm 9, causing the clay medium to compact and consolidate. The elastic diaphragm 9 provides flexible pressure equalization, avoiding localized stress concentration and preventing fine clay particles from overflowing upwards. After compaction, the consolidated thickness of the clay medium is approximately 200 μm. Step 3: Remove the partition 7 from the insertion hole 17, restoring the vertical direct connection between the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6, forming a clay-water-bearing layer micro-interface. Attach and fix the cover plate slide 4 to the upper cover plate 3, and tighten it with the slide sealing screw 19 to form a microscopic observation window. A sealing gasket can be placed between the cover plate slide 4 and the cover plate 3 to prevent leakage in this step. Step 4: Slowly inject deionized water into the simulated cavity 6 of the aquifer through the groundwater injection interface 12 until the entire system is completely saturated and there are no air bubbles left, thus establishing the initial aqueous environment. Step 5: Load the stained chlorobenzene into a syringe, install it into a high-precision automatic injection pump, and connect it to the organic pollutant injection interface 14. Place the assembled chip body 1 on the stage of a high-powered microscope with a high-speed camera, adjust the light source and focus, and focus on the contact interface between the clay layer simulation cavity 5 and the water-bearing sand layer simulation cavity 6; start the automatic injection pump, set a constant micro-flow rate (5μL / min) to push the fluid containing chlorobenzene droplets toward the clay layer interface. Stop the injection when the chlorobenzene fills the entire water-bearing sand layer. Replace the chlorobenzene with a prepared groundwater solution, and push the groundwater toward the water-bearing sand layer at a constant flow rate (50μL / min). Throughout the process, use a high-speed camera to continuously record video or capture images at a fixed frequency (10 frames per second), recording the distribution of chlorobenzene, the morphology and size of chlorobenzene droplets, the phase transition of chlorobenzene, and the evolution of the dominant flow channel in real time; at the same time, acquire dynamic change information of the clay fracture structure.

[0039] Step Six: After the experiment, export the microscopic image data, such as... Figure 5 As shown in the figure. The acquired images were analyzed using image processing software (ImageJ). The scale (8 mm) in the figure was used for calibration. The contact angle of the chlorobenzene droplets at the interface was measured, and the number, area and equivalent diameter of the chlorobenzene droplets were counted. The critical capillary pressure required for the droplets to enter the clay pore throat was calculated.

[0040] Experimental results show that the distribution of chlorobenzene in aquifers is closely related to groundwater flow velocity, pore structure, and the physical properties of the sand-clay interface. When chlorobenzene fills the sand layer (left figure), it mainly fills larger pores, presenting as droplets with complete morphology and clear interfaces. During groundwater flushing (right figure), chlorobenzene undergoes significant changes under shear force and hydrodynamic action, exhibiting droplet contraction, splitting, and redistribution, with some droplets remaining in the large pore region. Due to capillary forces and differences in permeability, chlorobenzene failed to effectively penetrate the clay simulation layer, forming significant residual droplets near the interface, while incompletely flushed droplets were compressed into more compact positions. This indicates that simple groundwater flushing is insufficient to completely remove residual chlorobenzene contaminants at the interface. The experiment also reveals that the bentonite layer near the interface can limit contaminant diffusion but increases the complexity of contaminant retention. In conclusion, the migration and residue behavior of contaminants are controlled by pore distribution and the clay interface.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A simulation experimental device for the migration of organic pollutants in clay-aquifers, comprising a chip body (1), characterized in that: The chip body (1) is assembled from a base plate (2) and an upper cover plate (3) to form a closed transparent sheet structure. The chip body (1) has a connected clay layer simulation cavity (5) and a water-containing sand layer simulation cavity (6) inside. The clay layer simulation cavity (5) is located in the upper half of the chip body (1) and is used to fill the clay medium; The water-bearing sand layer simulation cavity (6) is located in the lower half of the chip body (1). One end of the water-bearing sand layer simulation cavity (6) is connected to a seepage channel (15) that is connected to the outside of the chip body (1) and used for fluid discharge. The other end of the water-bearing sand layer simulation cavity (6) is connected to a groundwater injection channel (11) and an organic pollutant injection channel (13) for fluid injection. The upper part of the clay layer simulation cavity (5) is provided with a compaction component for compacting the clay medium. A partition (7) that can be pulled out from the side of the chip body (1) is provided between the clay layer simulation cavity (5) and the water-bearing sand layer simulation cavity (6). The partition (7) isolates the clay layer simulation cavity (5) and the water-bearing sand layer simulation cavity (6) during the compaction of the clay medium by the compaction component, and is pulled out after the compaction component is completed to restore the connection between the clay layer simulation cavity (5) and the water-bearing sand layer simulation cavity (6).

2. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 1, characterized in that: The base plate (2) and the top cover plate (3) are fitted together. The clay layer simulation cavity (5) and the water-bearing sand layer simulation cavity (6) are both opened on the base plate (2) and located on the side where the base plate (2) and the top cover plate (3) are fitted together. The base plate (2) and the top cover plate (3) are fixed with main body fixing screws (18).

3. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 2, characterized in that: The compaction assembly includes a compaction plate (8) and compaction screws (10). The compaction plate (8) is horizontally positioned inside the clay layer simulation cavity (5) near the top. The width of the compaction plate (8) is adapted to the width of the clay layer simulation cavity (5). Several compaction screws (10) are threaded onto the top of the base plate (2), and the bottom of several compaction screws (10) penetrates the base plate (2) into the clay layer simulation cavity (6) to apply pressure to the compaction plate (8).

4. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 3, characterized in that: The compaction assembly also includes an elastic diaphragm (9), which is disposed between the compaction sheet (8) and the clay medium to achieve flexible pressure equalization and sealing isolation.

5. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 2, characterized in that: The upper cover plate (3) has a transverse insertion hole (17) at the middle of the clay layer simulation cavity (5) and the water-bearing sand layer simulation cavity (6). The cross section of the insertion hole (17) is adapted to the cross section of the partition plate (7), and the partition plate (7) is pulled out through the insertion hole (17).

6. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 5, characterized in that: It also includes a cover glass slide (4), which is attached and fixed to the side of the upper cover plate (3) of the chip body (1) away from the bottom plate (2) after the partition plate (7) is pulled out, so as to form a microscopic observation window. The cover glass slide (4) and the upper cover plate (3) are fixed with glass slide sealing screws (19).

7. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 1, characterized in that: The chip body (1) is provided with a groundwater injection interface (12) connected to the groundwater injection channel (11), an organic pollutant injection interface (14) connected to the organic pollutant injection channel (13), and a pollutant outflow interface (16) connected to the seepage channel (15) at both ends. The groundwater injection interface (12) and the organic pollutant injection interface (14) are both suitable for connection to an external automatic injection pump or pipeline system.

8. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 1, characterized in that: The seepage channel (15) is a porous network structure with different pore sizes.

9. The experimental apparatus for simulating the migration of organic pollutants in clay-aquifers according to claim 1, characterized in that: The chip body (1) is made of transparent quartz glass to meet the requirements of resistance to organic pollutants, organic solvent corrosion and microscopic observation.

Images