Construction method of reticulated laterite impermeable layer based on ICP experiment
Through the ICP experiment method, the penetration behavior of the reticular red soil samples at different dry density and heavy metal ion concentrations was studied, and the dry density structure with the highest adsorption efficiency was selected to solve the efficiency of the reticular red soil anti-seepage layer under heavy metal pollution conditions in the existing technology, achieving efficient and environmentally friendly anti-seepage effect.
Patent Information
- Application Number
- CN202510302969.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-05-30
AI Technical Summary
The prior art lacks systematic research on the penetration characteristics, microstructure changes and penetration behavior under different conditions under heavy metal pollution conditions, making it difficult to construct an efficient anti-seepage layer of red soil in the red soil.
Using the ICP experiment method, a dry density gradient of reticular red soil soil sample and a heavy metal ion solution with a preset dry density gradient was prepared, and a permeability experiment was carried out to study the adsorption efficiency of the soil sample to heavy metal ions, and a dry density structure with the highest adsorption efficiency was selected to construct a red soil seepage anti-seepage layer of the reticular red soil with the highest adsorption efficiency.
The structure of the reticular red soil anti-seepage layer with an adsorption efficiency of more than 90% of the heavy metal ions under heavy metal pollution conditions has been achieved. The method uses natural soil materials, which is environmentally friendly and low-cost, and is suitable for large-scale promotion.
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Figure CN120064063A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of soil engineering and pollution control, and particularly relates to a method for constructing a lateritic red soil impermeable layer based on ICP experiments. Background Technique
[0002] With the acceleration of the industrialization process, the problem of environmental pollution has become increasingly severe. In particular, the prevention and control of heavy metal pollution have become a major challenge in the fields of global environmental protection and ecological restoration. Currently, the mainstream impermeable layer materials are generally bentonite, high-density polyethylene, polyvinyl chloride, geotextile, rubber, and polypropylene, etc. These materials have high water impermeability, which affects the infiltration of water flow. In rainy areas in the south, it is easy to cause floods, and the materials themselves are not easily degraded, which will cause pollution to the ecological environment.
[0003] As an important natural resource and component of the ecological environment, the permeability and pollution control ability of soil directly affect the diffusion and accumulation of heavy metal pollutants. At present, researchers have explored the heavy metal adsorption capacity of different types of soil and proposed different soil improvement methods to enhance their pollution prevention and control ability. Most of the clays studied are standard clays prepared in the laboratory. In terms of the research on clays in actual areas, there are more studies on the loess in the Yellow River Basin at present. At the same time, most studies focus on the adsorption characteristics of heavy metals and the use of soil modifiers, and lack in-depth discussion on the permeability changes under heavy metal pollution conditions. Current research mostly focuses on traditional soil impermeable materials, such as bentonite, clay, etc. There is still a lack of systematic theoretical and experimental support for the permeability, adsorption, and long-term stability of lateritic red soil as a heavy metal pollution prevention and control material.
[0004] Lateritic red soil is a natural clay widely distributed in the areas south of the Yangtze River in China. It has good adsorption, low permeability, and high compaction strength, and has been widely used in engineering construction in recent years. Certain progress has been made in the field of impermeability and pollution prevention and control of lateritic red soil in the prior art, but there are still many technical defects to be solved urgently. Especially under heavy metal pollution conditions, the infiltration characteristics, microstructural changes of lateritic red soil, and its infiltration behavior under different copper ion concentrations and different soil sample densities have not been systematically and comprehensively studied. Therefore, there is an urgent need for a method to construct a lateritic red soil impermeable layer by combining different concentration conditions and different soil dry densities. Summary of the Invention
[0005] The purpose of the present invention is to provide a method for constructing a lateritic red soil impermeable layer based on ICP experiments.
[0006] The present invention provides a method for constructing a lateritic red soil impermeable layer based on ICP experiments, including the following steps:
[0007] S1. Prepare soil samples with a preset dry density gradient by compaction method;
[0008] S2. Prepare heavy metal ion solutions with a preset concentration gradient;
[0009] S3. Refer to the "Standard for Geotechnical Test Methods", and use heavy metal ion solutions with a preset concentration to conduct permeability tests on the soil samples with a dry density gradient, and obtain the relationship between the adsorption efficiency of the soil samples with a density gradient and the corresponding concentration of heavy metal ion solutions;
[0010] S4. According to the relationship between the adsorption efficiency obtained in step S3, select the dry density with the highest adsorption efficiency for the actual construction of the lateritic red soil impervious layer.
[0011] Further, step S1 specifically includes the following steps:
[0012] S11. Obtain lateritic red soil, dry, crush and sieve it, uniformly add distilled water according to a preset moisture content, and then add a preset amount of activated carbon and mix evenly to obtain intermediate product 1;
[0013] S12. Calculate the weight of intermediate product 1 required for preparing soil samples according to the preset dry density gradient respectively, then add them into the compactor and compact to the required dry density, and use a ring knife to cut the samples to obtain the soil samples with the preset dry density gradient.
[0014] Further, in step S11, after the lateritic red soil is dried, crushed and sieved through a 0.5 mm sieve, it is then spread out on a tray, distilled water is weighed according to a moisture content of 24% and filled into a spray bottle, and the soil is evenly moistened with the spray bottle.
[0015] Further, in step S11, the added activated carbon accounts for 0-9% of the total mass.
[0016] Further, the dry density is the ratio of the mass of solid particles to the total volume of the soil sample.
[0017] The range of the dry density gradient is 1-2 g / cm 3 .
[0018] Preferably, the dry density gradient is specifically: 1.4 g / cm 3 , 1.5 g / cm 3 , 1.55 g / cm 3 , 1.6 g / cm 3 .
[0019] Further, in step S2, the heavy metal ion solutions include copper sulfate solution and copper chloride solution.
[0020] The concentration gradient is the concentration gradient range of copper ion content from 0 to 15 g / L.
[0021] Preferably, the concentration gradient of copper ions is specifically: 0.5 g / L, 1.0 g / L, 3.0 g / L, 5.0 g / L, 8.0 g / L, 9.0 g / L, 10.0 g / L, 11.0 g / L.
[0022] Further, in step S3, the penetration experiment is specifically as follows: Place the soil sample in a permeameter, connect the water head pipe to the permeameter, fill the variable water head pipe with a copper ion solution. Before the experiment starts, expel all the bubbles in the inlet pipe, and then let the copper ion solution start to penetrate and saturate the soil sample. When the penetration state reaches stability, collect the filtrate at the outlet of the permeameter at preset time intervals. After the experiment ends, conduct an inductively coupled plasma optical emission spectrometry experiment analysis (ICP-OSE) on the collected filtrate, quantitatively analyze the copper ion concentration in the filtrate, obtain the remaining copper ion concentration in the filtrate, and thus calculate the adsorption efficiency of the soil sample for copper ions.
[0023] Further, step S4 is specifically as follows: According to the adsorption efficiency data of the concentration gradient heavy metal ion solution corresponding to the dry density of the soil sample obtained in step S3, select the dry density with an adsorption efficiency greater than 90% according to the actual application situation, and construct the lateritic red soil impervious layer according to the selected dry density.
[0024] Preferably, when the dry density of the soil sample is greater than 1.6 g / cm 3 , the heavy metal adsorption efficiency reaches more than 90%.
[0025] Principle of the present invention:
[0026] When the copper ion concentration is low (i.e., 0.5 g / L, 1.0 g / L), fewer ions react with the inside of the soil mass. It is mainly affected by the osmotic pressure difference, and the inside of the soil mass mainly undergoes osmotic consolidation, and the soil mass is compacted, making its permeability coefficient show a decreasing trend. As the copper ion concentration further increases, at this time, the hydrolysis adsorption reaction is dominant inside the soil mass, and the soil structure and the connection between particles are damaged, thus increasing more tiny pores. And during the long-term penetration process, the soil particles will agglomerate, further increasing the internal pore channels. The change of the internal pores of the lateritic red soil leads to the enhancement of its permeability. Therefore, the higher the ion concentration, the more obvious the hydrolysis adsorption effect in the soil mass. By studying the adsorption efficiency of the lateritic red soil for copper ions, the optimal dry density for using the lateritic red soil as an impervious layer is obtained.
[0027] Beneficial effects of the present invention:
[0028] (1) By studying the variation law of the permeability of the lateritic red soil and pollutants, the method of the present invention constructs a lateritic red soil impervious layer with a heavy metal ion adsorption efficiency reaching more than 90%.
[0029] (2) The construction process of the reticulate laterite anti-seepage layer constructed by the method of the present invention completely uses natural soil materials, which is more environmentally friendly and has lower costs compared with the existing chemical material anti-seepage layers, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 It is a physical diagram of the compactor for preparing soil samples in the embodiment;
[0031] Figure 2 It is a schematic structural diagram of the permeation device for conducting permeation tests in the embodiment;
[0032] Figure 3 It is a curve showing the change of the copper ion concentration in the permeate with time in the permeation experiment of the reticulate laterite soil sample permeating copper sulfate solution in the embodiment;
[0033] Figure 4 It is a curve showing the change of the copper ion concentration in the permeate with time in the permeation experiment of the reticulate laterite soil sample permeating copper chloride solution in the embodiment;
[0034] Figure 5 It is a comparison diagram showing the change of the adsorption rate with the adsorption time in the permeation experiment of the reticulate laterite soil sample and the activated carbon reticulate laterite mixed soil sample in the embodiment;
[0035] Figure 6 It is a diagram of the surface permeation velocity of the soil sample when the solution permeates the reticulate laterite soil sample in the COMSOL porous media flow simulation in the embodiment;
[0036] Figure 7 It is a diagram of the liquid seepage velocity of the cross-section of the soil sample when the solution permeates the reticulate laterite soil sample in the COMSOL porous media flow simulation in the embodiment;
[0037] Figure 8 It is a diagram of the copper ion concentration distribution in the soil sample when the solution permeates the reticulate laterite soil sample in the COMSOL porous media flow simulation in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0038] In the embodiments of the present invention, the reticulate laterite used is remolded soil sample preparation, that is, after the new moist reticulate laterite is dried, it is ground and pulverized and then sieved through a 0.5 mm sieve, and stored at normal temperature and dried for standby. Table 1 shows the basic physical properties of the obtained clay.
[0039] Table 1 Physical and mechanical property indexes of reticulate laterite
[0040]
[0041] Experimental material preparation in Example 1
[0042] Spread the dried and sieved soil evenly on the tray. Weigh distilled water according to a water content of 24% and pour it into a sprayer. Use the sprayer to evenly moisten the soil until the set water content is reached to obtain moist soil. Calculate the weight of the required moist soil based on the dry density, put it into a compactor and compact it to the required dry density. Use a core cutter (Φ61.8×40mm) in the permeameter to cut the compacted soil sample to obtain a soil sample with the corresponding dry density. The physical diagram of the compactor is as shown in Figure 1 shown.
[0043] According to the above method, prepare lateritic red soil samples with dry densities of 1.4 g / cm 3 , 1.5 g / cm 3 , 1.55 g / cm 3 , 1.6 g / cm 3 .
[0044] Then spread the dried and sieved soil evenly on the tray. Weigh distilled water according to a water content of 24% and pour it into a sprayer. Use the sprayer to evenly moisten the soil until the set water content is reached, and add activated carbon so that the mass fraction of activated carbon in the obtained product is 6% to obtain an intermediate product. Calculate the weight of the required intermediate product based on the dry density, put it into a compactor and compact it to the required dry density. Use a core cutter (Φ61.8×40mm) in the permeameter to cut the compacted soil sample to obtain a soil sample with the corresponding dry density.
[0045] According to the above method, prepare activated carbon lateritic red soil mixed soil samples with dry densities of 1.4 g / cm 3 , 1.5 g / cm 3 , 1.55 g / cm 3 , 1.6 g / cm 3 .
[0046] Weigh CuSO 4 ·5H 2 O and CuCl 2 ·2H 2 O respectively to prepare heavy metal ion solutions with copper ion contents of 0.5 g / L, 1.0 g / L, 3.0 g / L, 5.0 g / L, 8.0 g / L, 9.0 g / L, 10.0 g / L, and 11.0 g / L.
[0047] Example 2 ICP Permeation Experiment of Lateritic Red Soil Samples
[0048] Respectively use copper ion solutions with copper ion contents of 0.5 g / L, 1.0 g / L, 3.0 g / L, 5.0 g / L, 8.0 g / L, 9.0 g / L, 10.0 g / L, and 11.0 g / L (including CuCl 2 and CuSO 4 ) to test the lateritic red soil samples with dry densities of 1.4 g / cm 3 , 1.5 g / cm3 , 1.55 g / cm 3 , 1.6 g / cm 3 of the reticular laterite soil samples for permeability tests.
[0049] The permeability test uses the variable head permeability test as Figure 2 shown. The permeability test is carried out with reference to the "Standard for Geotechnical Test Methods" (GB50123 - 2019). The prepared soil sample is placed into the permeameter, and at the same time, the water head tube is connected to the permeameter. The variable head tube is filled with copper ion solution. Before the test starts, all the air bubbles in the inlet pipe are expelled, and then the copper ion solution is allowed to permeate and saturate the soil sample. One soil sample is permeated for five days, and its leachate is collected regularly every day for record. The leachate is generated by the permeation of the current day. After collecting the leachate of the current day, the excess leachate in the beaker is poured out and the beaker is rinsed clean, and then the leachate of the next day is collected. Finally, the ion concentration in the leachate is measured by ICP - OSE.
[0050] Taking the copper ion concentration of the permeate as the vertical coordinate and the permeation time as the horizontal coordinate to plot a graph, the image is as Figure 3 shown. It can be seen from Figure 3 that the five - day heavy metal adsorption efficiencies of the reticular laterite with a dry density of 1.4 g / cm 3 are 77.27%, 52.27%, 32.73%, 31.82%, 26.37 respectively; those of the reticular laterite with a dry density of 1.5 g / cm3 are 82.53%, 67.42%, 58.51%, 56.67%, 37.71% respectively; those of the reticular laterite with a dry density of 1.55 g / cm 3 are 85.31%, 69.59%, 62.71%, 55.53%, 40.51% respectively; those of the reticular laterite with a dry density of 1.6 g / cm 3 are 98.13%, 96.21%, 96.05%, 94.35%, 93.74% respectively. The adsorption efficiency of the reticular laterite with a dry density of 1.6 g / cm 3 reaches more than 90%, and the anti - seepage effect is the best.
[0051] Example 3 ICP Permeation Experiment of Activated Carbon - Reticular Laterite Mixed Soil Samples
[0052] Using copper ion solution (CuSO 4 ) with a copper ion content of 10.0 g / L to conduct permeability tests on the activated carbon - reticular laterite mixed soil samples and reticular laterite soil samples with dry densities of 1.4 g / cm 3 , 1.5 g / cm 3 , 1.55 g / cm 3 , 1.6 g / cm 3 respectively.
[0053] The constant-head permeability test was adopted, as shown in Figure 2 . The permeability test was carried out with reference to the "Standard for Geotechnical Test Methods" (GB50123-2019). The prepared soil sample was placed into the permeameter, and at the same time, the water head pipe was connected to the permeameter. The variable-head pipe was filled with copper ion solution. Before the test started, all the bubbles in the water inlet pipe were expelled, and then the copper ion solution was allowed to permeate and saturate the soil sample. One soil sample was permeated for five days, and its leachate was collected regularly every day for recording. The leachate was generated by the permeation of the current day. After collecting the leachate of the current day, the excess leachate in the beaker was poured out and the beaker was rinsed clean, and then the leachate of the next day was collected. Finally, the ion concentration in the leachate was measured by ICP-OSE.
[0054] Taking the adsorption rate as the ordinate and the permeation time as the abscissa, a graph was plotted, as shown in Figure 4 . Among them, D1 was the experimental group of the activated carbon reticular laterite mixed soil sample, and D2 was the control group of the reticular laterite soil sample. As can be seen from Figure 4 , adding a certain amount of activated carbon to the reticular laterite can improve the adsorption rate of the reticular laterite to copper ions, and further enhance the anti-seepage effect of the reticular laterite. Generally speaking, after adding activated carbon, the adsorption rate of the reticular laterite to copper ions has increased by 1%-3%.
[0055] Example 4 COMSOL porous media flow simulation experiment
[0056] The process of the solution permeating through the reticular laterite specimen was simulated by COMSOL porous media flow. Since the water flow permeates from bottom to top during the constant-head permeation process, and the actual permeation process is a saturated permeation mode. In order to more clearly observe this permeation process, COMSOL was used for numerical simulation, and the entire permeation process follows Darcy's law.
[0057] In this example, a copper ion solution with a concentration of 0.5 mol / L was selected to permeate the reticular laterite with a dry density of 1.6 g / cm 3 . The actual size of the specimen was Φ61.8×40 mm.
[0058] Figure 5 Figure shows the surface seepage velocity of the soil sample during the simulation of the solution permeating through the reticular laterite soil sample by COMSOL porous media flow. By observing the seepage velocity of the permeating liquid in the specimen, it can be seen that the order of magnitude of the seepage velocity range is about 10 -8 . At this time, the permeability coefficient of the soil sample obtained through the permeability test is also about 10 -8 , which verifies the results of the permeability test.
[0059] Secondly, by observing the seepage velocity on the surface of the soil sample, it can be seen that the seepage velocity of the liquid around the specimen is not very uniform. This is because when the soil sample is placed in the permeameter cutter, the surface of the soil sample and the cutter are not in full and complete contact, but there are some uneven contacts of pore particles.
[0060] Figure 6 This is the liquid seepage velocity diagram of the soil sample section when simulating the solution seepage through the reticular laterite soil sample by COMSOL porous media flow in the embodiment. By observing the seepage velocity of the liquid on the soil sample section, it can be seen that inside the soil sample, the seepage velocity of the liquid is relatively uniform, generally around 1.23×10 -8 or so, which also conforms to the results obtained in the variable head permeability experiment.
[0061] Figure 7 This is the copper ion concentration distribution diagram of the soil sample when simulating the solution seepage through the reticular laterite soil sample by COMSOL porous media flow in the embodiment. By observing the distribution of copper ions in the soil sample, it can be seen that the copper ion concentration also shows a decreasing trend from bottom to top. First of all, this is because the permeating liquid permeates from bottom to top, which makes more copper ions accumulate at the lower end of the soil sample at the water inlet end. As the penetration further deepens, the copper ions in the soil sample diffuse upward, but the concentration is lower. Under the action of the water pressure inside the soil mass, the copper ions will also diffuse downward, which results in the situation shown in the figure. It can be seen from the figure that the copper ion content at the upper end of the soil sample is very low, basically around 0.1 g / L, while the copper ion concentration at the lower end of the soil sample reaches more than 0.4 g / L. Through calculation, it can be known that the adsorption efficiency of the reticular laterite with a dry density of 1.6 g / cm 3 for copper ions in the permeating liquid reaches more than 90%, which also conforms to the adsorption efficiency of the reticular laterite calculated in the ICP test.
Claims
1. A method for constructing a reticulated red soil anti-seepage layer based on ICP experiment, characterized in that: The following steps are involved: S1. Prepare soil samples with a preset dry density gradient by compaction method; S2. Preparing a heavy metal ion solution with a preset concentration gradient; S3. Referring to the Standard for Geotechnical Test Methods, a permeation test was conducted on a soil sample with a dry density gradient using a heavy metal ion solution of a preset concentration to obtain a relationship between the adsorption efficiency of the soil sample with a density gradient and the heavy metal ion solution of the corresponding concentration; S4. According to the adsorption efficiency variation relationship obtained in step S3, the dry density with the highest adsorption efficiency is selected to construct the actual reticulated red soil anti-seepage layer.
2. The method for constructing an anti-seepage layer of reticulated red soil based on ICP experiment according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11. Obtain reticulated red clay, dry it, crush it, and sieve it. Weigh distilled water evenly according to the preset moisture content to obtain a moist reticulated red clay. S12. Calculate the weight of moistened reticulated red soil required for preparing soil samples according to the preset dry density gradient, add the soil samples to the compactor and compact them to the required dry density, use a circular knife to cut the samples, and obtain soil samples with the preset dry density gradient.
3. The method for constructing an anti-seepage layer of reticulated red soil based on ICP experiment according to claim 2, characterized in that: In step S11, the reticulated red clay is dried and crushed, passed through a 0.5 mm sieve, and then spread on a tray. Distilled water is weighed according to a preset moisture content and put into a spray pot, and the soil is evenly moistened with the spray pot.
4. The method for constructing an anti-seepage layer of reticulated red soil based on ICP experiment according to claim 2, characterized in that: The dry density is the ratio of the mass of solid particles to the total volume of soil; the dry density gradient range is 1 to 2 g / cm 3 .
5. The method for constructing an anti-seepage layer of reticulated red soil based on ICP experiment according to claim 4, characterized in that: The dry density gradient is: 1.4g / cm 3 , 1.5g / cm 3 , 1.55g / cm 3 , 1.6g / cm 3 .
6. The method for constructing an anti-seepage layer of reticulated red soil based on ICP test according to claim 1, characterized in that: In step S2, the heavy metal ion solution includes a copper sulfate solution and a copper chloride solution; the concentration gradient is a copper ion content concentration gradient range of 0 to 15 g / L.
7. The method for constructing an anti-seepage layer of reticulated red soil based on ICP test according to claim 6, characterized in that: The specific concentration gradient of copper ion content is: 0.5g / L, 1.0g / L, 3.0g / L, 5.0g / L, 8.0g / L, 9.0g / L, 10.0g / L, and 11.0g / L.
8. The method for constructing an anti-seepage layer of reticulated red soil based on ICP test according to claim 1, characterized in that: In step S3, the permeability experiment is specifically as follows: placing the soil sample into the permeameter, connecting the water head pipe to the permeameter, filling the variable water head pipe with copper ion solution, driving out all the bubbles in the water inlet pipe before the start of the experiment, and then allowing the copper ion solution to begin to permeate the saturated soil sample, when the permeability state reaches stability, collecting the filtrate at the outlet of the permeameter at preset time intervals, and after the experiment, performing inductively coupled plasma emission spectroscopy experimental analysis on the collected filtrate, and performing quantitative analysis on the copper ion concentration in the filtrate to obtain the residual copper ion concentration in the filtrate, thereby calculating the adsorption efficiency of the reticulated red soil sample for copper ions.
9. The method for constructing an anti-seepage layer of reticulated red soil based on ICP test according to claim 1, characterized in that: Step S4 specifically comprises: according to the adsorption efficiency data of the dry density of the corresponding reticulated red soil sample to the concentration gradient heavy metal ion solution obtained in step S3, according to the actual application situation, selecting the dry density with an adsorption efficiency greater than 90%, and constructing the reticulated red soil anti-seepage layer according to the selected dry density.
10. The method for constructing an anti-seepage layer of reticulated red soil based on ICP test according to claim 9, characterized in that: The dry density of reticulated red soil is greater than 1.6g / cm 3 The heavy metal adsorption efficiency reaches over 90%.