A bentonite impermeable barrier material and method of making the same

Abstract

This application relates to the field of contaminated site barrier, and discloses a bentonite seepage barrier material and its preparation method, comprising calcium-based bentonite, Mg(OH)2, γ-Al2O3, and surfactant SDBS; wherein the amount of Mg(OH)2 is 5%-25% of the calcium-based bentonite, the amount of γ-Al2O3 is 2%-10% of the calcium-based bentonite, and the amount of SDBS is 1%-7% of Mg(OH)2. This invention utilizes Mg(OH)2 and γ-Al2O3 under the action of surfactant SDBS, with bentonite as a carrier, whose gelling properties allow them to be loaded onto the bentonite surface or pillared between bentonite layers, increasing the ion exchange capacity and spatial holding capacity of the bentonite, thereby improving the seepage barrier performance of the modified bentonite material against metal ions.

Description

Technical Field

[0001] This invention relates to the field of contaminated site barrier technology, specifically to a bentonite seepage barrier material and its preparation method. Background Technology

[0002] In recent years, firstly, the rapid development of cities has generated a large amount of domestic waste; secondly, the rapid development of industry and mining has resulted in tailings that have nowhere to be dumped. Landfilling is a common method of waste disposal. In order to reduce pollution to the underground environment, an impermeable layer is usually laid to prevent pollutants from migrating to groundwater. Waste liquids can be collected and treated in a timely manner, or any occasional release of pollutants can be contained and blocked to allow them to be released slowly.

[0003] Currently, commonly used seepage-proofing layers both domestically and internationally include bentonite, clay, red mud, cement, magnesium aluminum silicate filler, and their corresponding modified forms, or used in combination with other solid waste materials, such as blast furnace slag and fly ash. Due to certain geographical locations, in-situ soil can meet the requirements for isolating pollution sources and preventing pollutant migration. With proper process design and construction, the pollution source can be controlled. However, this situation is relatively rare, and most working conditions cannot meet this requirement. In such cases, additives are needed. A common method is to use in-situ soil-bentonite barrier materials, where the proportion of bentonite can be adjusted to achieve the corresponding seepage prevention standards and barrier capacity.

[0004] When the proportion of bentonite added is small, the long-term effects of pollutants may cause the impermeable layer to thin and gradually lose its seepage prevention and interception capabilities. Conversely, a larger amount will increase the cost. There is also a cement-bentonite combined system, but cement is prone to cracking during geological activity, and the solidified cement can become an obstacle in the soil. Due to cracks and other factors, its permeability coefficient is generally below 10. -5 -10 -6 The seepage coefficient (cm / s) can be reduced by adding fly ash or blast furnace slag. There are also cases where soil-cement-bentonite are used in combination, but cement production emits large amounts of greenhouse gases, contradicting the current trend of carbon neutrality and development; therefore, cement is rarely used as a seepage barrier.

[0005] Under the dual-carbon development goals, turning waste into treasure is a popular research direction. Fly ash, a byproduct of coal combustion, can be utilized as a resource, reducing environmental pollution and improving economic efficiency. Existing technologies utilize fly ash as an anti-seepage grouting material; after solidification, the grout forms a continuous and complete curtain, fundamentally cutting off the seepage and recharge channels of groundwater in mining areas, achieving a good anti-seepage effect. However, this material does not provide a large space for metal ions to reside; once the curtain is damaged, its blocking effect will completely disappear. Therefore, the development of barrier materials that can both accommodate heavy metals and prevent seepage is urgently needed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a bentonite seepage barrier material and its preparation method. By utilizing Mg(OH)2 and γ-Al2O3 under the action of surfactant SDBS, and using bentonite as a carrier, the ion exchange capacity of bentonite is increased, and the spatial capacity of bentonite is improved, thereby enhancing the seepage barrier performance of modified bentonite material against metal ions.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: a bentonite seepage barrier material, comprising calcium-based bentonite, Mg(OH)2, γ-Al2O3 and surfactant SDBS;

[0008] The amount of Mg(OH)2 used is 5%-25% of calcium-based bentonite, the amount of γ-Al2O3 used is 2%-10% of calcium-based bentonite, and the amount of SDBS used is 1%-7% of Mg(OH)2.

[0009] Preferably, the amount of SDBS used is 3% of Mg(OH)2.

[0010] Preferably, the amount of Mg(OH)2 used is 15%-20% of the calcium-based bentonite.

[0011] Preferably, the amount of γ-Al2O3 used is 5% of calcium-based bentonite.

[0012] Preferably, the amount of Mg(OH)2 is 20% of the calcium-based bentonite, the amount of γ-Al2O3 is 5% of the calcium-based bentonite, and the amount of SDBS is 3% of the Mg(OH)2.

[0013] This invention provides a method for preparing bentonite seepage-proof barrier material, comprising the following steps:

[0014] S1. Weigh the specified amounts of Mg(OH)2 and γ-Al2O3, place them in an aqueous solution and stir until homogeneous, then ultrasonically disperse them into a suspension;

[0015] S2. Add the specified amount of SDBS to the suspension and sonicate again to reduce the tension between Mg(OH)2 and γ-Al2O3 and the water interface.

[0016] S3. Add calcium-based bentonite to the S2 mixture, stir to ensure that the calcium-based bentonite is in full contact with Mg(OH)2 and γ-Al2O3, allow it to stand for hydration, dry it, and then crush and grind it to obtain the final product.

[0017] Preferably, the amount of calcium-based bentonite added is 5g.

[0018] Preferably, the stirring time in step S1 is 5-10 min and the ultrasonic dispersion time is 10-20 min.

[0019] Preferably, the ultrasonic dispersion time in step S2 is 10-20 min.

[0020] Preferably, in step S3, the stirring time is 20-30 hours, the static hydration time is 20-30 hours, and the drying temperature is 80-100℃.

[0021] This invention provides a bentonite seepage-proof barrier material and its preparation method. It has the following beneficial effects:

[0022] 1. This invention utilizes Mg(OH)₂ and γ-Al₂O₃, under the action of the surfactant SDBS, with bentonite as a carrier. Through their gelling properties, they can be loaded onto the bentonite surface or pillared between bentonite layers, increasing the ion exchange capacity and spatial holding capacity of the bentonite, thereby improving the seepage prevention and interception performance of the modified bentonite material against metal ions. Secondly, γ-Al₂O₃ is porous with a large surface area, can activate mineral surface groups, and has excellent adsorption and water purification properties, good stability, and strong corrosion resistance. This results in a modified bentonite with high adsorption capacity, low permeability, and excellent stability.

[0023] 2. Heavy metal ion solutions leached from tailings ponds are mostly acidic. This invention modifies bentonite with Mg(OH)₂, which improves the soil pH environment and adjusts the pH of the aquatic environment, providing a suitable pH range for the formation of Pb and Zn ions and complexes, causing them to precipitate and preventing re-dissolution. This increases the adsorption capacity of bentonite for Pb and Zn. Simultaneously, other metal ions tend to precipitate under alkaline conditions, thus also acting as a barrier against other heavy metals. Furthermore, Mg(OH)₂-modified bentonite creates an alkaline environment to precipitate metal ions for barrier purposes. Compared to strong alkali NaOH, Mg(OH)₂ has a slow-release OH⁻ effect. - The ability to prevent the immediate release of large amounts of OH groups into the environment. - This has an impact on the environment.

[0024] 3. Both Mg(OH)2 and γ-Al2O3 are sparingly soluble substances with very low solubility, so they cannot react directly with bentonite. They need to be treated before the reaction. In this invention, a certain amount of SDBS, an anionic surfactant, is added, which can effectively reduce the interfacial tension between the two phases and enable the insoluble solid powder to be fully dispersed and suspended in the liquid. Attached Figure Description

[0025] Figure 1 The chemical composition (a) and XRD pattern (b) of the calcium-based bentonite of the present invention are shown.

[0026] Figure 2 This is a schematic diagram of Experimental Example 1 of the present invention, wherein, Figure 2-1 This is a schematic diagram showing the solid-liquid volume after 24 hours of static operation under the influence of SDBS factors. Figure 2-2 This is a schematic diagram showing the effect of SDBS dosage on solid-liquid separation after 24 hours of stillness. Figure 2-3 The effect of SDBS dosage on Pb 2+ -Zn 2+ Schematic diagram illustrating the effect of adsorption capacity;

[0027] Figure 3 This is a schematic diagram of Experimental Example 2 of the present invention, wherein, Figure 3-1 This is a schematic diagram showing the solid-liquid volume of Mg(OH)2 after 24 hours of static liquid reaction under various influencing factors. Figure 3-2 The effect of Mg(OH)2 dosage on Pb 2+ -Zn 2+ Schematic diagram illustrating the effect of adsorption capacity;

[0028] Figure 4 This is a schematic diagram of Experimental Example 3 of the present invention, wherein, Figure 4-1 This is a schematic diagram showing the solid-liquid volume of γ-Al2O3 after 24 hours of static state under the influence of various factors. Figure 4-2 This is a schematic diagram showing the effect of γ-Al₂O₃ dosage on solid-liquid separation after 24 hours of stillness. Figure 4-3 The effect of γ-Al2O3 dosage on Pb 2+ -Zn 2+ Schematic diagram illustrating the effect of adsorption capacity;

[0029] Figure 5 This is a schematic diagram of the expansion volume of modified bentonite in an orthogonal experiment of Experiment Example 4 of the present invention;

[0030] Figure 6 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a bentonite seepage barrier material, comprising: calcium-based bentonite, Mg(OH)2, γ-Al2O3 and surfactant SDBS.

[0033] Specifically, this invention utilizes Mg(OH)₂ and γ-Al₂O₃, under the action of the surfactant SDBS, with bentonite as a carrier. Through their gelling properties, they can be loaded onto the bentonite surface or pillared between bentonite layers, increasing the ion exchange capacity and spatial holding capacity of the bentonite, thereby improving the seepage prevention and interception performance of the modified bentonite material against metal ions. Secondly, γ-Al₂O₃ is porous with a large surface area, can activate mineral surface groups, and has excellent adsorption and water purification properties, good stability, and strong corrosion resistance. This results in a modified bentonite with high adsorption capacity, low permeability, and excellent stability.

[0034] Heavy metal ion solutions leached from tailings ponds are mostly acidic. This invention modifies bentonite with Mg(OH)₂, which improves the soil pH environment and adjusts the pH of the aquatic environment, providing a suitable pH range for the formation of Pb and Zn ions and complexes, causing them to precipitate and preventing re-dissolution. This increases the adsorption capacity of bentonite for Pb and Zn. Simultaneously, other metal ions tend to precipitate under alkaline conditions, thus also acting as a barrier for other heavy metals. Furthermore, Mg(OH)₂-modified bentonite creates an alkaline environment to precipitate metal ions for barrier purposes. Compared to strong alkali NaOH, Mg(OH)₂ has a slow-release OH⁻ effect. - The ability to prevent the immediate release of large amounts of OH groups into the environment. - This has an impact on the environment.

[0035] Among them, the seepage barrier material is Mg-AlLHCB (Mg-Al layered hydroxides cementitious bentonite).

[0036] The chemical composition analysis results of calcium-based bentonite are as follows: Figure 1 As shown in a, the XRD patterns and analysis results of the mineral phases are as follows: Figure 1 As shown in b.

[0037] The main component is montmorillonite [(Na,Ca)]0.33 (Al,Mg)2Si4O 10 [(OH)2·nH2O], soapstone [Ca] 0.2 (Al,Mg)2Si4O 10 [(OH)2·4H2], kaolin [Al2O·2SiO2·2H2O] and SiO2. In addition, the colloidal value of this bentonite was tested to be 11.06 (mL / 3g) and the pH was 10.12.

[0038] Magnesium hydroxide, with the molecular formula Mg(OH)2, is a white powder. It is of analytical grade, with an active ingredient content of ≥98%. Its chemical registration number is CAS: 1309-42-8. It is produced by Chengdu Kelong Chemical Co., Ltd.

[0039] Nano-alumina, with the molecular formula Al2O3 (γ-Al2O3), is a white powder with a particle size of 20 nm. It contains ≥99% active ingredients and has the chemical registry number (CAS: 1344-28-1). It is produced by Aladdin Reagent (Shanghai) Co., Ltd.

[0040] SDBS, chemical formula C 18 H 29 NaO3S is used as a surfactant.

[0041] like Figure 6 As shown, this embodiment of the invention provides a method for preparing bentonite seepage-proof barrier material, comprising the following steps:

[0042] S1. Weigh out the specified amounts of Mg(OH)2 and γ-Al2O3, place them in an aqueous solution and stir for 5-10 minutes until homogeneous. Then, sonicate for 10-20 minutes to fully disperse them into a suspension.

[0043] S2. Add the specified amount of SDBS to the suspension and sonicate again for 10-20 minutes to reduce the tension between Mg(OH)2 and γ-Al2O3 and the water interface, so that Mg(OH)2 and γ-Al2O3 are fully emulsified.

[0044] S3. Add 5g of calcium-based bentonite to the S2 mixture and stir for 20-30h to allow the calcium-based bentonite to fully contact Mg(OH)2 and γ-Al2O3, thereby activating the properties between the minerals. Allow it to stand for hydration for 20-30h, dry it at 80-100℃, and then crush and grind it to obtain the final product.

[0045] Specifically, Mg(OH)2 and γ-Al2O3 are both sparingly soluble substances with very low solubility, so they cannot react directly with bentonite. They need to be treated before the reaction. In this invention, a certain amount of SDBS, an anionic surfactant, is added, which can effectively reduce the interfacial tension between the two phases and enable the insoluble solid powder to be fully dispersed and suspended in the liquid.

[0046] In the process of preparing modified bentonite, many factors can affect the heavy metal adsorption capacity and water absorption and swelling capacity of the synthesized bentonite. Therefore, determining the appropriate experimental conditions and the ratio of material additions is an important prerequisite for obtaining ideal modified bentonite. This invention analyzes and compares the influencing factors of the synthesis process of Mg(OH)2 and γ-Al2O3 modified bentonite through simple experiments and orthogonal experiments.

[0047] Example 1:

[0048] Bentonite seepage prevention materials include:

[0049] Calcium-based bentonite, 5g

[0050] Mg(OH)2, 20% of the mass of calcium-based bentonite, i.e., 1g

[0051] Al2O3, 5% of the mass of calcium-based bentonite, i.e., 0.25g

[0052] The amount of SDBS and Mg(OH)2 used is 0%, i.e., 0g.

[0053] Example 2:

[0054] It is basically the same as Example 1, except that:

[0055] SDBS, Mg(OH)2 dosage is 1%, i.e. 0.01g.

[0056] Example 3:

[0057] It is basically the same as Example 1, except that:

[0058] The amount of SDBS and Mg(OH)2 used is 3%, i.e., 0.03g.

[0059] Example 4:

[0060] It is basically the same as Example 1, except that:

[0061] The amount of SDBS and Mg(OH)2 used is 5%, i.e., 0.05g.

[0062] Example 5:

[0063] It is basically the same as Example 1, except that:

[0064] The amount of SDBS and Mg(OH)2 used is 7%, i.e., 0.07g.

[0065] Experimental Example 1:

[0066] Analysis of the effects of varying SDBS dosage on bentonite reaction phenomena, water absorption and swelling properties, and Pb adsorption. 2+ Zn 2+ The testing and assessment of abilities.

[0067] The free expansion test method for bentonite was carried out according to the American Society for Testing and Materials (ASTM D5890-11). The specific experimental steps are as follows: Pour about 80 mL of the contaminated solution into a 100 mL graduated cylinder. Gradually and slowly sprinkle the air-dried bentonite into the solution in small amounts several times. After the previous sample has completely sunk to the bottom, slowly add more. After all the sample has been added, slowly add the solution along the wall of the graduated cylinder to the 100 mL mark. After standing for 24 hours, read the expansion volume of the bentonite.

[0068] The expansion volume of the modified bentonite after synthesis and standing for 24 hours is as follows: Figure 2-1 As shown, the solid-liquid volumes under the influence of SDBS for 24 hours in Examples 1-5 are respectively displayed.

[0069] The phenomena observed during the experiment are shown in Table 1:

[0070] Table 1

[0071]

[0072]

[0073] The metal ion contamination solutions used in the adsorption characteristic experiments were prepared from Pb(NO3)2 and Zn(NO3)2·6H2O, both of which were analytical grade with a purity greater than 99%. Single heavy metal contamination solutions and composite contamination solutions with a concentration ratio of 1:1 were included; in the composite contamination solution, the concentration referred to was the total concentration of the two contaminating metal ions.

[0074] SDBS dosage on Pb 2+ -Zn 2+ The effect of adsorption capacity is as follows Figure 2-3 As shown, for Pb 2+ and Zn 2+ Mixed solutions, whether RB (raw bentonite) or Mg-Al LHCB, affect Pb 2+ The adsorption capacity of both is greater than that of Zn. 2+ In Pb 2+ Under conditions of low total amount, its adsorption rate is close to 100%, which can be understood as, in the case of Pb 2+and Zn 2+ In the mixed solution, bentonite preferentially adsorbs Pb. 2+ This is related to the properties of the ions. Lead has a higher specific gravity than zinc and is less reactive, making it easier to deposit and be adsorbed. Compared with the adsorption capacity of RB, the adsorption capacity of Mg-Al LHCB is significantly higher; compared to the total adsorption capacity, the adsorption capacity of Mg-Al LHCB is almost twice that of RB. Furthermore, experimental results show that when the SDBS addition is 0%, the surface tension of Mg(OH)2 and nano-Al2O3 is too high, preventing sufficient contact and reaction with bentonite, resulting in excess reagent and waste. Although Mg-Al LHCB is more effective than RB in adsorbing Pb... 2+ and Zn 2+ The adsorption capacities of all Mg-Al LHCBs increased, but this may be due to the effect of unreacted Mg(OH)₂ and γ-Al₂O₃. With increasing SDBS addition, the adsorption capacity of Mg-Al LHCB for Pb... 2+ and Zn 2+ Adsorption capacity and 24h expansion volume ( Figure 2-1 A cutoff point appears at an addition level of 3%. When the addition level of SDBS exceeds 3%, the effect of modified bentonite on Pb decreases. 2+ and Zn 2+ The adsorption capacity does not change much, and the volume of water absorption and expansion is inversely proportional. Synthetic bentonite becomes loose after absorbing water, with more suspended matter and voids, and low density, which is not conducive to its use as a seepage prevention material.

[0075] Therefore, the optimal addition amount of SDBS is 3%. Under this condition, neither an excess of Mg(OH)2 and nano-Al2O3 nor a waste of SDBS on Pb is caused. 2+ and Zn 2+ It also has a high adsorption capacity.

[0076] Example 6:

[0077] Bentonite seepage prevention materials include:

[0078] Calcium-based bentonite, 5g

[0079] Al2O3, 5% of the mass of calcium-based bentonite, i.e., 0.25g

[0080] Mg(OH)2, 0% of the mass of calcium-based bentonite, i.e., 0g

[0081] SDBS, Mg(OH)2 dosage is 3%, i.e. 0g.

[0082] Example 7:

[0083] It is basically the same as Example 6, except that:

[0084] Mg(OH)2, 5% of the mass of calcium-based bentonite, i.e., 0.25g

[0085] The amount of SDBS and Mg(OH)2 used is 3%, i.e., 0.0075g.

[0086] Example 8:

[0087] It is basically the same as Example 6, except that:

[0088] Mg(OH)2, 10% of the mass of calcium-based bentonite, i.e., 0.5g

[0089] The amount of SDBS and Mg(OH)2 used is 3%, i.e., 0.015g.

[0090] Example 9:

[0091] It is basically the same as Example 6, except that:

[0092] Mg(OH)2, 15% of the mass of calcium-based bentonite, i.e., 0.75g

[0093] The amount of SDBS and Mg(OH)2 used is 3%, which is 0.0225g.

[0094] Example 10:

[0095] It is basically the same as Example 6, except that:

[0096] Mg(OH)2, 20% of the mass of calcium-based bentonite, i.e., 1g

[0097] The amount of SDBS and Mg(OH)2 used is 3%, i.e., 0.03g.

[0098] Example 11:

[0099] It is basically the same as Example 6, except that:

[0100] Mg(OH)2, 25% of the mass of calcium-based bentonite, i.e., 1.25g

[0101] The amount of SDBS and Mg(OH)2 used is 3%, which is 0.0375g.

[0102] Experimental Example 2:

[0103] Under the same experimental conditions as in Example 1, the effects of changing the amount of Mg(OH)2 on the reaction phenomena of bentonite, water absorption and swelling, and Pb adsorption were analyzed. 2+ Zn 2+ The testing and assessment of abilities.

[0104] The expansion volume of the modified bentonite after synthesis and standing for 24 hours is as follows: Figure 3-1As shown, the solid-liquid volumes of Mg(OH)2 after 24 hours of static ignition under the influence of various factors in Examples 6-11 are respectively shown.

[0105] The phenomena observed during the experiment are shown in Table 2:

[0106] Table 2

[0107] <![CDATA[Mg(OH)2]]> Experimental phenomena 0％ <![CDATA[A large amount of nano-Al2O3 floats on the liquid surface and does not come into complete contact with bentonite, and the solid-liquid separation filtration speed is relatively fast]]> 5％ <![CDATA[The solid and liquid are almost integrated, and a small amount of Mg(OH)2 and active Al2O3 float on the surface]]> 15％ The solid surface has micropores, the solid-liquid interface is clear, and the solid-liquid separation and filtration speed is relatively fast. 20％ The solid surface has no micropores, the solid-liquid interface is clear, and the solid-liquid separation and filtration speed is relatively slow. 25％ The solid surface has no micropores, the solid-liquid interface is clear, and the solid-liquid separation filtration speed is the slowest.

[0108] Regarding the volume expansion of bentonite, when the Mg(OH)2 content is greater than 5%, the volume expansion coefficient actually decreases slightly. This may be because as the Mg(OH)2 content increases, the cementitious properties between bentonite particles strengthen, reducing the swelling capacity of the bentonite. However, the bentonite after absorbing water is compact, non-porous, and has strong adhesion. Table 2 shows that when the Mg(OH)2 addition is 0%, even with the addition of SDBS, Al2O3 remains suspended on the liquid surface, indicating that SDBS has little effect on Al2O3. However, as the Mg(OH)2 addition increases, the remaining reagent decreases. This is because, under the cementitious effect of Mg(OH)2, the probability of Al2O3 contacting the bentonite increases, acting as an adhesive and forming Mg-Al hydroxide. Figure 3-2 Experimental results show that with the increase of Mg(OH)2 addition, the modified bentonite has an effect on Pb 2+ and Zn 2+ The adsorption capacity of all Pb was improved. When the addition amount reached 10%, the adsorption capacity of Pb was significantly improved. 2+ The adsorption capacity of the modified bentonite first reaches a stable level, with an adsorption rate approaching 100%. With continued addition of Mg(OH)₂, the adsorption capacity of the modified bentonite for Zn₂ increases. 2+ The adsorption capacity gradually increases, but when the addition amount is greater than 20%, the increase in adsorption capacity is not significant. Furthermore, comparing the adsorption capacity of bentonite before and after modification shows that the amount of Mg(OH)2 added is the main influencing factor. Therefore, the optimal addition amount of Mg(OH)2 is 15%–20%.

[0109] Example 12:

[0110] Bentonite seepage prevention materials include:

[0111] Calcium-based bentonite, 5g

[0112] Mg(OH)2, 20% of the mass of calcium-based bentonite, i.e., 1g

[0113] The amount of SDBS and Mg(OH)2 used is 3%, i.e., 0.03g.

[0114] Al2O3, 0% of the mass of calcium-based bentonite, i.e., 0g.

[0115] Example 13:

[0116] It is basically the same as Example 12, except that:

[0117] Al2O3, 2% of the mass of calcium-based bentonite, i.e., 0.1g.

[0118] Example 14:

[0119] It is basically the same as Example 12, except that:

[0120] Al2O3, 5% of the mass of calcium-based bentonite, i.e., 0.25g.

[0121] Example 15:

[0122] It is basically the same as Example 12, except that:

[0123] Al2O3, 8% of the mass of calcium-based bentonite, i.e., 0.40g.

[0124] Example 16:

[0125] It is basically the same as Example 12, except that:

[0126] Al2O3, 10% of the mass of calcium-based bentonite, i.e., 0.50g.

[0127] Experimental Example 3:

[0128] Under the same experimental conditions as in Example 1, the effects of changing the amount of Al2O3 on the reaction phenomena of bentonite, water absorption and swelling, and Pb adsorption were analyzed. 2+ Zn 2+ The testing and assessment of abilities.

[0129] The expansion volume of the modified bentonite after synthesis and standing for 24 hours is as follows: Figure 4-1 As shown, the solid-liquid volumes of Al2O3 under static conditions for 24 hours in Examples 12-16 are respectively displayed.

[0130] The phenomena observed during the experiment are shown in Table 3:

[0131] Table 3

[0132]

[0133]

[0134] Adsorption experiment results are as follows Figure 4-3 As shown, when the Mg(OH)2 addition amount is 20%, with the increase of the addition amount of nano-Al2O3, the modified bentonite has an effect on Pb. 2+ The adsorption capacity reaches nearly 100% for Zn. 2+The adsorption capacity gradually increases, possibly due to the addition of Al2O3, which timely replenishes the aluminum ions lost in bentonite due to magnesium ion exchange and increases the amount of Mg(OH)2 adsorbed. Furthermore, the stable Al2O3 structure may also be activated by energy transfer under stirring, entering the bentonite interlayer and acting as a pillar, expanding the interlayer spacing and increasing its space-holding capacity. The Al in Al2O3 may also react with the OH in Mg(OH)2. - The compounds combine to form hydroxides, resulting in flocculation and adsorption. Therefore, when the amount of nano-Al2O3 is 5%, the modified bentonite exhibits good adsorption capacity and swelling performance.

[0135] Experiment Example 4:

[0136] The experimental conditions were the same as in Example 1. Two parameters were used as evaluation indicators: the expansion volume of the modified bentonite and the total adsorption capacity for metal ions.

[0137] The experimental content and results are shown in Table 4:

[0138] Table 4

[0139]

[0140]

[0141] like Figure 5 As shown in Table 4, the volume change of modified bentonite in the orthogonal reaction experiment was investigated. Al2O3 was the main factor affecting the volume expansion of bentonite, and its addition amount was inversely proportional to the volume expansion, indicating a correlation with flocculation. Table 4 shows that the significance of each factor is close to 0.05, thus the experimental results are reliable. The range analysis results show that the influence of each factor on the experimental results is in the order of Mg(OH)2 addition > Al2O3 addition > SDBS addition. When the Mg(OH)2 addition amount is 5%, there is always residual reagent after the reaction. Based on the single-factor experimental results, it can be inferred that under sufficient surfactant action, the residual reagent is Al2O3. Due to the small amount of Mg(OH)2 added, it cannot fully react with Al2O3. This phenomenon does not exist when the addition amount exceeds 15% and the SDBS addition amount exceeds 3%. When the addition amount was 15% and the SDBS addition amount was 1%, there was still reagent residue. This was because the amount of surfactant added was insufficient, preventing Mg(OH)2 and Al2O3 from fully contacting the bentonite. When the SDBS addition amount exceeded 3%, there was no excess of any reactant. Therefore, based on the analysis of the experimental data from Examples 1-3, the optimal synthesis conditions for modified bentonite are 20% Mg(OH)2, 5% Al2O3, and 3% SDBS.

[0142] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bentonite seepage-proof barrier material, characterized in that, Including calcium-based bentonite, Mg(OH)2, γ-Al2O3 and surfactant SDBS; The amount of Mg(OH)2 is 20% of the calcium-based bentonite, the amount of γ-Al2O3 is 5% of the calcium-based bentonite, and the amount of SDBS is 3% of the Mg(OH)2.

2. A method for preparing a bentonite seepage barrier material, used to prepare the bentonite seepage barrier material as described in claim 1, characterized in that, Includes the following steps: S1. Weigh the specified amounts of Mg(OH)2 and γ-Al2O3, place them in an aqueous solution and stir until homogeneous, then ultrasonically disperse them into a suspension; S2. Add the specified amount of SDBS to the suspension and sonicate again to reduce the tension between Mg(OH)2 and γ-Al2O3 and the water interface. S3. Add calcium-based bentonite to the S2 mixture, stir to ensure that the calcium-based bentonite is in full contact with Mg(OH)2 and γ-Al2O3, allow it to stand for hydration, dry it, and then crush and grind it to obtain the final product.

3. The method for preparing a bentonite seepage-proof barrier material according to claim 2, characterized in that, The amount of calcium-based bentonite added is 5g.

4. The method for preparing a bentonite seepage-proof barrier material according to claim 2, characterized in that, In step S1, the stirring time is 5-10 min and the ultrasonic dispersion time is 10-20 min.

5. The method for preparing a bentonite seepage-proof barrier material according to claim 2, characterized in that, The ultrasonic dispersion time in step S2 is 10-20 min.

6. The method for preparing a bentonite seepage-proof barrier material according to claim 2, characterized in that, In step S3, the stirring time is 20-30 hours, the static hydration time is 20-30 hours, and the drying temperature is 80-100℃.

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