Device for measuring diffusion coefficient when solution permeates bentonite barrier and use method of device

Abstract

The invention provides a device for measuring a diffusion coefficient when a solution penetrates through a bentonite barrier and a use method of the device, and belongs to the technical field of geotechnical engineering. An upper-layer diffusion system, a middle-layer diffusion system and a lower-layer diffusion system are constructed through the containing space defined by the three cylinders, in the diffusion system, bentonite serves as a water-resisting layer to separate a high-concentration solution on the upper layer from a low-concentration solution on the lower layer, the concentration change of the solutions is reflected by measuring the resistivity of the solutions before and after penetrating through the bentonite, and the concentration of the solutions is measured through the resistivity of the solutions before and after penetrating through the bentonite. Therefore, the diffusion coefficient of the solution penetrating through the bentonite is determined, and simple measurement of the diffusion coefficient of the solution penetrating through the bentonite barrier is realized.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, specifically relating to a device for measuring the diffusion coefficient of a solution passing through a bentonite barrier and its usage method. Background Technology

[0002] Bentonite, as a seepage control material, possesses excellent hygroscopic expansion properties, high adsorption capacity, low permeability, and good self-sealing properties, and is widely used in various seepage control projects. Studies have shown that the permeability of bentonite varies under different concentrations and with different ions, thus affecting its ion-blocking effect and resulting in differences in the diffusion coefficient of ions passing through the bentonite barrier. Therefore, to address the ion-blocking problem in bentonite seepage control projects, it is necessary to conduct indoor static experiments to investigate the diffusion of solutions with different times, concentrations, and ions through the bentonite barrier.

[0003] However, because bentonite's ion exchange in solution often varies under different environments, and it is quite difficult to measure the ion concentration in solution in real time, there are currently no testing devices or experimental studies for ion concentration exchange in bentonite layers under different ion concentration environments.

[0004] Therefore, it is necessary to provide a device for measuring the diffusion coefficient of a solution passing through a bentonite barrier and a method for using it to solve the above problems. Summary of the Invention

[0005] This invention provides a device and method for measuring the diffusion coefficient of a solution passing through a bentonite barrier. Bentonite is used as a water-impermeable layer to separate a high-concentration solution in the upper layer from a low-concentration solution in the lower layer. The concentration change of the solution is reflected by measuring the resistivity of the bentonite before and after diffusion, thereby determining the diffusion coefficient of the solution passing through the bentonite. This invention simplifies the measurement of the diffusion coefficient of a solution passing through a bentonite barrier and effectively solves at least one of the technical problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows: A device for measuring the diffusion coefficient of a solution passing through a bentonite barrier, comprising: Hollow cylinder; Two parallel, spaced, permeable covers divide the hollow area of ​​the cylinder into a first storage space, a second storage space, and a third storage space that are connected sequentially from top to bottom. The first storage space is filled with a first liquid medium, the second storage space is filled with a bentonite layer, and the third storage space is filled with a second liquid medium. The first liquid medium and the second liquid medium are solutions of the same ion with different concentrations, and the concentration of the first liquid medium is higher than that of the second liquid medium. The measuring component is used to measure the resistivity change of the bentonite layer before and after diffusion, calculate the solution concentration in the bentonite layer before and after diffusion by converting resistivity to solution concentration, and calculate the diffusion coefficient of the solution through the bentonite barrier based on Fick's law.

[0007] As a preferred improvement, the cylinder has a split structure, including an upper cylinder, a middle cylinder, and a lower cylinder. The permeable cover includes an upper permeable cover and a lower permeable cover. The upper permeable cover is sandwiched between the upper cylinder and the middle cylinder, and the lower permeable cover is sandwiched between the middle cylinder and the lower cylinder. The first storage space is surrounded by the upper cylinder, the second storage space is surrounded by the middle cylinder, and the third storage space is surrounded by the lower cylinder.

[0008] As a preferred improvement, the openings at both ends of the cylinder are sealed by cover plates, and the two cover plates are fastened together by threaded posts, so that the two cover plates cooperate to clamp the upper cylinder, middle cylinder and lower cylinder.

[0009] As a preferred improvement, permeable stones are provided on both the upper and lower sides of the bentonite layer.

[0010] As a preferred improvement, the permeable cover plate is provided with a plurality of perforations for solution to pass through, and the perforation diameter is 2mm.

[0011] As a preferred improvement, the measuring components include a first measuring component, a second measuring component, and a third measuring component, wherein the first measuring component is used to measure the resistivity of the first liquid medium; the second measuring component is used to measure the resistivity of the bentonite layer; and the third measuring component is used to measure the resistivity of the second liquid medium.

[0012] A method of using a diffusion coefficient measuring device for a solution passing through a bentonite barrier as described above includes the following steps: Step S1: Construct the resistivity-concentration standard curve of the bentonite layer; Step S2: Measure the change in resistivity of the bentonite layer before and after diffusion, and calculate the solution concentration in the bentonite layer before and after diffusion by using the conversion relationship between resistivity and solution concentration. Step S3: Calculate the diffusion coefficient of the solution through the bentonite barrier based on Fick's law.

[0013] The beneficial effects of this invention are as follows: (1) A diffusion system with upper, middle and lower layers is constructed by the containment space enclosed by three cylinders. In the diffusion system, bentonite is used as a water-proof layer to separate the high-concentration solution in the upper layer and the low-concentration solution in the lower layer. The change in solution concentration is reflected by measuring the resistivity of the solution before and after passing through the bentonite, and then the diffusion coefficient of the solution when passing through the bentonite is determined, thus realizing the simplified measurement of the diffusion coefficient of the solution when passing through the bentonite barrier. (2) The measuring device has a simple overall structure and low cost. It can better reproduce the state of bentonite in complex engineering environments. The measurement results can be used to guide the application of bentonite seepage prevention materials in actual engineering. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 A schematic diagram showing the structure of the diffusion coefficient measuring device for the solution passing through the bentonite barrier provided in Example 1; Figure 2 express Figure 1 The diagram shows the usage status of the measuring device. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0016] Example 1 like Figures 1-2 As shown, this embodiment provides a diffusion coefficient measuring device for a solution passing through a bentonite barrier, including a cylinder 10, a permeable cover plate 20, a sealing plate 30, a threaded column 40, and a measuring component 50.

[0017] The cylinder 10 has a hollow structure, and two parallel and spaced permeable cover plates 20 divide the hollow area of ​​the cylinder 10 into a first storage space 10A, a second storage space 10B, and a third storage space 10C that are connected sequentially from top to bottom.

[0018] To facilitate the installation of the permeable cover plate 20, the present invention designs the cylinder 10 as a split structure, including an upper cylinder 11, a middle cylinder 12, and a lower cylinder 13 arranged coaxially. The upper cylinder 11, middle cylinder 12, and lower cylinder 13 are all cylindrical hollow structures. The two permeable covers 20 are defined as an upper permeable cover plate 21 and a lower permeable cover plate 22, respectively. The upper permeable cover plate 21 is sandwiched between the upper cylinder 11 and the middle cylinder 12, and the lower permeable cover plate 22 is sandwiched between the middle cylinder 12 and the lower cylinder 13.

[0019] The upper permeable cover plate 21 has annular grooves at the edges of its top and bottom surfaces. The bottom of the upper cylinder 11 is engaged in the groove on the top surface of the upper permeable cover plate 21, and the top of the middle cylinder 12 is engaged in the groove on the bottom surface of the upper permeable cover plate 21. Similarly, the lower permeable cover plate 22 has annular grooves at the edges of its top and bottom surfaces. The bottom of the middle cylinder 12 is engaged in the groove on the top surface of the lower permeable cover plate 22, and the bottom of the lower cylinder 13 is engaged in the groove on the bottom surface of the lower permeable cover plate 22. These grooves provide radial restraint, ensuring the connection stability of the upper cylinder 11, middle cylinder 12, and lower cylinder 13 and preventing radial displacement. Furthermore, to ensure sealing, sealing rings are installed in the grooves of the upper and lower permeable cover plates 21 and 22. The sealing rings can be made of flexible materials such as rubber or silicone.

[0020] Structurally, the first storage space 10A is surrounded by the upper cylinder 11, the second storage space 10B is surrounded by the middle cylinder 12, and the third storage space 10C is surrounded by the lower cylinder 13.

[0021] The cover plate 30 is used to cover the openings at both ends of the cylinder 10. Specifically, the cover plate 30 includes an upper cover plate 31 and a lower cover plate 32. The upper cover plate 31 is used to cover the top opening of the upper cylinder 11, and the lower cover plate 32 is used to cover the bottom opening of the lower cylinder 13. An annular groove is provided at the bottom edge of the upper cover plate 31, and the top of the upper cylinder 11 is correspondingly engaged in the groove of the upper cover plate 31. Similarly, an annular groove is provided at the top edge of the lower cover plate 32, and the bottom of the lower cylinder 13 is correspondingly engaged in the groove of the lower cover plate 32. Likewise, sealing rings are also required in the grooves of the upper cover plate 31 and the lower cover plate 32 to ensure a tight seal.

[0022] The threaded post 40 connects two sealing plates 30. By adjusting the distance between the two sealing plates 30, the two sealing plates 30 are driven to clamp the upper cylinder 11, the middle cylinder 12, and the lower cylinder 13. The threaded post 40 includes a head 41, a rod 42, and a nut 43. The head 41 is located above the upper sealing plate 31, and the nut 43 is located below the lower sealing plate 32. The top of the rod 42 is fixed to the head 41, and the bottom passes through the upper sealing plate 31 and the lower sealing plate 32 in sequence to connect with the nut 43. The outer surface of the rod 42 is provided with external threads, which are tightened with the internal threads of the nut 43. By adjusting the position of the nut 43 on the rod 42, the upper sealing plate 31 and the lower sealing plate 32 are driven to move towards each other, clamping the upper cylinder 11, the middle cylinder 12, and the lower cylinder 13.

[0023] After the cylinder 10, the permeable cover plate 20, the sealing plate 30, and the threaded column 40 are assembled, the first storage space 10A, the second storage space 10B, and the third storage space 10C form a sealed space, which is filled with a first liquid medium, bentonite, and a second liquid medium, respectively. The first liquid medium is a high-concentration sodium chloride solution, and the second liquid medium is a low-concentration sodium chloride solution.

[0024] The permeable cover plate 20 is provided with perforations, each with a diameter of 2mm, the number of which is selected according to the size of the permeable cover plate 20. To enhance the strength of the permeable cover plate 20, both the top and bottom surfaces are plated with metal sheets. Specifically, the perforations on the upper permeable cover plate 21 connect the first storage space 10A and the second storage space 10B, and the perforations on the lower permeable cover plate 22 connect the second storage space 10B and the third storage space 10C.

[0025] The top and bottom surfaces of the bentonite layer 60 are both covered with permeable stones 70. The permeable stones 70 can ensure the passage of solution while preventing the loss of bentonite.

[0026] The upper cover plate 31 is provided with a first liquid inlet path for injecting a first liquid medium into the first storage space 10A. The first liquid inlet path includes a first liquid inlet on the side of the upper cover plate 31, a first liquid outlet on the bottom surface of the upper cover plate 31, and a first pipe connecting the first liquid inlet and the first liquid outlet. The first liquid inlet is connected to a first liquid medium source, and the first liquid outlet is connected to the first storage space 10A.

[0027] The lower cover plate 32 is provided with a second liquid inlet path for injecting a second liquid medium into the third storage space 10C. The second liquid inlet path includes a second liquid inlet located on the side of the lower cover plate 32, a second liquid outlet located on the top surface of the lower cover plate 32, and a second pipe connecting the second liquid inlet and the second liquid outlet. The second liquid inlet is connected to a second liquid medium source, and the second liquid outlet is connected to the third storage space 10C.

[0028] The assembly process of the measuring device is as follows: (1) Place the lower cover plate 32 on the platform and assemble the lower cylinder 13 above the lower cover plate 32; (2) Place the lower permeable cover plate 22 on the top of the lower cylinder 13, and assemble the middle cylinder 12 above the lower permeable cover plate 22; (3) Vacuum saturate the bentonite to ensure that the pores of the soil sample are completely filled with water to eliminate air bubbles; (4) A layer of permeable stone is laid on the lower permeable cover plate 22, and then bentonite is filled on the permeable stone to form the bentonite layer 60. Then another layer of permeable stone is laid on the bentonite layer 60. (5) Assemble the upper permeable cover plate 21 on the top of the middle cylinder 12, and assemble the upper cylinder 11 above the upper permeable cover plate 21; (6) Place the upper cover plate 31 on the top of the upper cylinder 11, and finally fix the upper cover plate 31 and the lower cover plate 32 with the threaded post 40.

[0029] The measurement system 50 includes a first measurement component 51, a second measurement component 52, and a third measurement component 53, all of which are fully automatic resistance recorders. Specifically: The upper cover plate 31 is also provided with a first wiring path. The first wiring path includes a first inlet on the side of the upper cover plate 31, a first outlet on the bottom surface of the upper cover plate 31, and a first wiring channel connecting the first inlet and the first outlet. The first inlet is connected to the outside, and the first outlet is connected to the first storage space 10A.

[0030] The upper permeable cover 21 is provided with a second wiring path and a third wiring path. The second wiring path includes a second inlet located on the side of the upper permeable cover 21, a second outlet located on the top surface of the upper permeable cover 21, and a second wiring channel connecting the second inlet and the second outlet. The second inlet is connected to the outside, and the second outlet is connected to the first storage space 10A. The third wiring path includes a third inlet located on the side of the upper permeable cover 21, a third outlet located on the bottom surface of the upper permeable cover 21, and a third wiring channel connecting the third inlet and the third outlet. The third inlet is connected to the outside, and the third outlet is connected to the second storage space 10B.

[0031] The lower permeable cover plate 22 is provided with a fourth wiring path 221 and a fifth wiring path 222. The fourth wiring path includes a fourth inlet on the side of the lower permeable cover plate 22, a fourth outlet on the top surface of the lower permeable cover plate 22, and a fourth wiring channel connecting the fourth inlet and the fourth outlet. The fourth inlet is connected to the outside, and the fourth outlet is connected to the second storage space 10B. The fifth wiring path includes a fifth inlet on the side of the lower permeable cover plate 22, a fifth outlet on the bottom surface of the lower permeable cover plate 22, and a fifth wiring channel connecting the fifth inlet and the fifth outlet. The fifth inlet is connected to the outside, and the fifth outlet is connected to the third storage space 10C.

[0032] The lower cover plate 32 is provided with a sixth wiring path 321. The sixth wiring path includes a sixth inlet on the side of the lower cover plate 32, a sixth outlet on the top surface of the lower cover plate 32, and a sixth wiring channel connecting the sixth inlet and the sixth outlet. The sixth inlet is connected to the outside, and the sixth outlet is connected to the third storage space 10C.

[0033] The first measuring component 51 includes a first upper measuring line 511 and a first lower measuring line 512. The first upper measuring line 511 is inserted into the top of the first liquid medium via the first wiring path 311; the first lower measuring line 512 is inserted into the bottom of the first liquid medium via the second wiring path 211.

[0034] The second measuring component 52 includes a second upper measuring line 521 and a second lower measuring line 522. The second upper measuring line 521 is inserted into the top of the bentonite layer 60 via the third wiring path 212; the second lower measuring line 522 is inserted into the bottom of the bentonite layer 60 via the fourth wiring path 221.

[0035] The third measuring component 53 includes a third upper measuring line 531 and a third lower measuring line 532. The third upper measuring line 531 is inserted into the top of the second liquid medium via the fifth wiring path 222; the third lower measuring line 532 is inserted into the bottom of the second liquid medium via the sixth wiring path 321.

[0036] It should be noted that after each measuring line is assembled into the corresponding wiring path, the wiring path needs to be sealed to prevent solution leakage. The sealing method is to inject sealant into the gaps of the wiring path.

[0037] The first measuring component 51 is used to measure the resistance of the first liquid medium, the second measuring component 52 is used to measure the resistance of the bentonite layer 60, and the third measuring component 53 is used to measure the resistance of the second liquid medium.

[0038] In the system of this invention, the bentonite layer 60 exists as a water-resistant layer. The ion concentration in the first liquid medium is higher than that in the second liquid medium, and ions in the first liquid medium spontaneously enter the second liquid medium through the pores of the bentonite. During the ion transfer process, the ion concentration of the bentonite layer 60 increases, its conductivity increases, and its resistance decreases. Based on the conversion relationship between resistance and concentration, by measuring the change in resistance of the bentonite layer 60, the change in ion concentration of the bentonite layer 60 can be calculated, and thus the diffusion coefficient can be determined.

[0039] Based on Fick's first law, the diffusion flux (diffusion mass flow rate) of a unit cross-sectional area perpendicular to the diffusion direction per unit time is proportional to the concentration gradient at that cross-section, expressed as: ; In the formula, Indicates diffusion flux; Indicates the diffusion coefficient; Indicates the volume concentration of the diffusing substance; "-" indicates the concentration gradient; "-" indicates that the diffusion direction is the opposite of the concentration gradient, that is, the diffusing substance diffuses from the high concentration area to the low concentration area. Indicates the diffusion distance.

[0040] Fick's second law, derived from Fick's first law and the law of conservation of mass, can predict the change in the concentration of diffusing substances over time due to diffusion; it is a parabolic partial differential equation. Based on Fick's second law, in unsteady diffusion processes, at a distance... At a given location, the rate of change of concentration over time is equal to the negative value of the change of diffusion flux over distance at that location, expressed as: ; In the formula, Indicates diffusion time.

[0041] For ease of calculation, this invention approximates the diffusion coefficient. Treating it as a constant, to achieve the desired diffusion coefficient The calculation only requires measuring the concentration change of the diffusing substance within a preset time period.

[0042] Within a solution, the diffuser decomposes (ionizes) into positively and negatively charged ions. These ions form the pathway for current transmission. The higher the ion concentration, the stronger the conductivity of the solution. Conversely, the stronger the conductivity, the weaker the resistance to current. Based on this relationship, this invention measures the change in solution concentration before and after diffusion by measuring the change in resistance of the solution.

[0043] Solution resistance Represented as: ; In the formula, Indicates the resistivity of the solution; Indicates the distance between parallel electrodes; Indicates the effective area of ​​the electrode; electrical conductivity resistivity The derivative of is used to measure the ease with which ions move in a solution. Substituting it into the resistance formula yields: ; In the formula, This represents the cell conductivity constant, which is a constant value.

[0044] electrical conductivity A physical quantity that measures the conductivity of a conductor, representing the ease with which ions in a solution pass through soil, is calculated as follows: ; The molar conductivity of a solution (eliminating the effect of concentration and focusing only on the conductivity of the ions themselves) is expressed as: .

[0045] Through the above process, a correlation was established between the solution concentration and molar conductivity and resistivity. In this practical application scenario, molar conductivity is considered a constant. At each time point, the resistance value measured by the second measuring component 52 can be used to calculate the ion concentration within the bentonite layer 60, and thus the ion concentration change within a preset time period can be calculated. The first measuring component 51 is used to monitor whether the concentration of the first liquid medium is constant to assist in verifying whether the diffusion experiment is proceeding smoothly; the third measuring component 53 is used to detect the concentration change of the second liquid medium to determine whether the diffusion process is proceeding normally. If the concentration of the second liquid medium increases rapidly in a short period of time, leakage may occur, and the experiment needs to be terminated.

[0046] diffusion coefficient By solving get.

[0047] To simplify operation, the diffusion coefficient The solution is obtained as follows: Calibration: Establish a resistivity-concentration standard curve for the bentonite layer 60; Conversion: The experimentally measured resistance is converted to concentration using a conversion standard curve. ; Computational mass: Calculating cumulative diffusion mass , Indicates the volume of the second storage space; Fitting and solving: plotting and At the relationship point, fit and solve for the slope. ; Final calculation: Substitute into the formula , This indicates the concentration of the first liquid medium.

[0048] The influence of bentonite's own ions also needs to be considered in the construction of the standard curve. Therefore, this invention uses soil cation exchange capacity (CEC), total soluble salts, and Na+ as the standard curve parameters. + Content, K + Content, Ca 2+ Content, Mg 2+ Content, HCO3 - Content, SO4 2- Content, Cl - With the content as independent variables X1, X2, X3, X4, X5, X6, X7, X8, and X9, and soil resistivity as the dependent variable Y1, model one was obtained through fitting: .

[0049] Model 1 fully considers the ions contained in bentonite itself and the ions used in the diffusion experiment, making the constructed resistance-concentration relationship more accurate and reducing the influence of bentonite's own ions.

[0050] In addition, soil resistivity decreases with increasing temperature, mainly because: (1) The viscosity of soil pore water decreases with increasing temperature, which leads to increased ion mobility and enhanced conductivity; (2) The degree of dissociation of pore water increases with increasing temperature, which in turn increases the mineralization of pore water and thus reduces resistivity.

[0051] Therefore, continuing to use soil moisture content as the independent variable Z1, soil temperature as the independent variable Z2, soil bulk density as the independent variable Z3, and soil resistivity as the dependent variable Y2, we can obtain Model 2: ; The output of Model 1 is used as the baseline for Model 2 for correction. The specific operation is as follows: Take a soil sample, measure all its chemical contents, and substitute them into Model 1 to calculate the theoretical resistivity Y1_ref of the soil at the inherent reference temperature T_ref of Model 1; The water content, temperature, and bulk density of the soil sample were measured and substituted into Model 2 to calculate the predicted value Y_temp(T_ref) of the temperature model at temperature T_ref.

[0052] By introducing a correction factor w, the results of Model 2 are consistent with those of Model 1 at temperature T_ref: w = Y1_ref / Y2_temp(T_ref).

[0053] The resistivity at any other temperature T can be predicted using the corrected Model 2: Y(T) = w × Y2.

[0054] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A device for measuring the diffusion coefficient of a solution passing through a bentonite barrier, characterized in that, include: Hollow cylinder; Two parallel, spaced, permeable covers divide the hollow area of ​​the cylinder into a first storage space, a second storage space, and a third storage space that are connected sequentially from top to bottom. The first storage space is filled with a first liquid medium, the second storage space is filled with a bentonite layer, and the third storage space is filled with a second liquid medium. The first liquid medium and the second liquid medium are solutions of the same ion with different concentrations, and the concentration of the first liquid medium is higher than that of the second liquid medium. The measuring component is used to measure the resistivity change of the bentonite layer before and after diffusion, calculate the solution concentration in the bentonite layer before and after diffusion by converting resistivity to solution concentration, and calculate the diffusion coefficient of the solution through the bentonite barrier based on Fick's law.

2. The diffusion coefficient measuring device for a solution permeating a bentonite barrier according to claim 1, characterized in that, The cylinder body has a split structure, including an upper cylinder, a middle cylinder and a lower cylinder. The permeable cover includes an upper permeable cover and a lower permeable cover. The upper permeable cover is sandwiched between the upper cylinder and the middle cylinder, and the lower permeable cover is sandwiched between the middle cylinder and the lower cylinder. The first storage space is surrounded by the upper cylinder, the second storage space is surrounded by the middle cylinder, and the third storage space is surrounded by the lower cylinder.

3. The diffusion coefficient measuring device for a solution permeating a bentonite barrier according to claim 2, characterized in that, The openings at both ends of the cylinder are sealed by cover plates, and the two cover plates are fastened together by threaded posts, so that the two cover plates cooperate to clamp the upper cylinder, middle cylinder and lower cylinder.

4. The device for measuring the diffusion coefficient of a solution passing through a bentonite barrier according to claim 1, characterized in that, Permeable stones are provided on both the upper and lower sides of the bentonite layer.

5. The diffusion coefficient measuring device for a solution permeating a bentonite barrier according to claim 1, characterized in that, The permeable cover plate is provided with multiple perforations for the solution to pass through, and the diameter of the perforations is 2mm.

6. The device for measuring the diffusion coefficient of a solution passing through a bentonite barrier according to claim 1, characterized in that, The measuring components include a first measuring component, a second measuring component, and a third measuring component. The first measuring component is used to measure the resistivity of the first liquid medium; the second measuring component is used to measure the resistivity of the bentonite layer. The third measuring component is used to measure the resistivity of the second liquid medium.

7. A method of using the diffusion coefficient measuring device for a solution permeating a bentonite barrier as described in any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Construct the resistivity-concentration standard curve of the bentonite layer; Step S2: Measure the change in resistivity of the bentonite layer before and after diffusion, and calculate the solution concentration in the bentonite layer before and after diffusion by using the conversion relationship between resistivity and solution concentration. Step S3: Calculate the diffusion coefficient of the solution through the bentonite barrier based on Fick's law.

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