A pre-hydrated bentonite impervious material and its preparation process

Abstract

The present application relates to the technical field of bentonite anti-seepage materials, and specifically discloses a prehydrated bentonite anti-seepage material and its preparation process. It is obtained by mixing the following raw materials in parts by mass: 80-90 parts of calcium bentonite, 10-12 parts of a binder, 5-8 parts of an organic composite component, and 3-5 parts of ethylene carbonate; the preparation steps include the following: taking calcium bentonite, crushing and sieving, then adding water to disperse, adjusting the pH, then adding ethylene carbonate, heating and stirring, then adding the organic composite component, continuing the process, then filtering and taking the solid part, adding the binder, and then performing a mold pressing process after mixing and coating, and cooling to obtain the result; wherein, the organic composite component is obtained by modifying the terminal amino group of acylated polyethylene glycol. The prehydrated bentonite anti-seepage material prepared by the preparation process of the present application has a water absorption rate of ≥5.2 and a water retention rate of ≥63.7%, and can significantly reduce the elution risk of small molecules of the intercalant.

Description

Technical Field

[0001] The present application relates to the technical field of bentonite anti-seepage materials, and more specifically, to a prehydrated bentonite anti-seepage material and a preparation process thereof. Background Art

[0002] Bentonite, an important non-metallic mineral material, has significant application value in engineering anti-seepage due to its unique expansibility, excellent adsorption properties, and good bonding characteristics. Its core component, montmorillonite, can absorb water several times its own volume, swelling upon contact with water to form a dense gel layer that effectively blocks water penetration. Bentonite anti-seepage products primarily include natural bentonite powder, sodium-based bentonite waterproofing blankets, and prehydrated bentonite anti-seepage materials. Prehydrated bentonite anti-seepage materials, based on their mature industrial production technology and efficient construction performance, demonstrate significant advantages in engineering applications.

[0003] The preparation process of prehydrated bentonite anti-seepage materials mainly includes: mixing bentonite and water in a specific proportion, adding a binder to form a homogeneous prehydrated slurry, then covering it with geotextile, and then molding it into a finished product; among them, sodium-based bentonite is an ideal bentonite raw material, but its high price limits its large-scale production and application; while calcium-based bentonite is cheap, but due to the influence of high-valent calcium ions in its structure, its interlayer spacing is relatively narrow, and the prehydrated bentonite anti-seepage materials directly obtained often do not have good water absorption and expansion properties.

[0004] Chinese patent application publication number CN117819561A discloses modified bentonite, its preparation method, bentonite-based anti-seepage materials, and their applications. The proposed method uses sodium hexafluorosilicate as an intercalating agent, which is then mixed with water to create a homogenous slurry. This slurry is then frozen to produce the modified bentonite. This intercalation method increases the interlayer spacing of the bentonite, ultimately improving its expansion and anti-seepage properties.

[0005] Although the above application documents can improve the expansion and anti-seepage properties of the anti-seepage material through the intercalation combination method, the intercalation agents used are mainly small molecules. After the intercalation treatment, the small molecule intercalation agents are easily affected by the external environment and eluted, and the water-locking performance of the modified bentonite also needs to be improved. Therefore, it is necessary to find a prehydrated bentonite anti-seepage material that takes into account the water absorption and expansion properties while reducing the risk of elution of the small molecule intercalation agent. Summary of the Invention

[0006] In order to further improve the water absorption and locking capacity of calcium-based bentonite anti-seepage materials and reduce the risk of elution of small molecule intercalants after intercalation modification, the present application provides a prehydrated bentonite anti-seepage material and a preparation process thereof.

[0007] In a first aspect, the present application provides a process for preparing a prehydrated bentonite anti-seepage material, which is obtained by mixing raw materials including the following parts by weight: 80-90 parts of calcium-based bentonite, 10-12 parts of a binder, 5-8 parts of an organic composite component, and 3-5 parts of ethylene carbonate; the preparation steps include the following:

[0008] Calcium-based bentonite is crushed and sieved, then dispersed with water, the pH is adjusted, and then ethylene carbonate is added. The mixture is heated and stirred, and then the organic composite component is added and the mixture is further treated. The solid portion is filtered and a binder is added. The mixture is then mixed, coated, and molded, and cooled to obtain the product.

[0009] The steps for preparing the organic composite component include the following:

[0010] [S01] dissolving oligomeric polyethylene glycol in a mixed solvent, then dropwise adding an acylating agent, reacting in the dark, then filtering under reduced pressure, adjusting the pH of the liquid phase, and sequentially separating by precipitation and rotary evaporation to obtain acylated polyethylene glycol;

[0011] [S02] Acylated polyethylene glycol is dispersed, and then p-toluenesulfonyl chloride is added. After the reaction, the mixture is rotary evaporated and then redissolved. Phthalimide is added, and potassium hydroxide solution is added dropwise. The mixture is heated, and then the solvent is removed, the mixture is redissolved, hydrazine hydrate is added, and the mixture is refluxed and purified to obtain the product.

[0012] By adopting the above technical solution, organic intercalation modified bentonite can be obtained. Ethylene carbonate, as a small molecule organic intercalation substance, can be inserted into the interlayer of montmorillonite structure in bentonite, and the carbonyl and ether oxygen groups in its molecular structure can interact with the Ca2+ interlayer of montmorillonite. 2+ The organic composite component can enter the montmorillonite interlayer through the expanded interlayer structure and play a role. In the structure of the organic composite component, the polyethylene glycol repeating chain segment can be used to capture water molecules and confine the water molecules in the montmorillonite layer structure, thereby improving the water-locking capacity. After the end amino group is modified, the lone pair electrons of the amino nitrogen atom introduced can bind to the Ca on the montmorillonite. 2+ The metal cations bind together through coordination, forming a stable ternary complex structure of "montmorillonite lamellae - metal cations - organic composite components." Within this complex structure, the organic composite components are distributed between the montmorillonite lamellae in a "comb"-like pattern. At the tail of the "comb," the short-chain acylated grafted groups, through the steric hindrance of the branched alkyl structure, increase the resistance of the intercalant, ethylene carbonate, to migration between the montmorillonite lamellae. This makes ethylene carbonate less susceptible to water migration and detachment from the intercalant, thereby reducing the risk of elution.

[0013] Preferably, the heating and stirring treatment is as follows: setting the temperature to 60-80° C., adjusting the stirring speed to 75-100 rpm, and stirring for 2-4 hours.

[0014] By adopting the above technical solution, the small molecule intercalant ethylene carbonate can be intercalated between the montmorillonite layers in bentonite. The heating and stirring treatment is beneficial to increasing the contact area between montmorillonite and ethylene carbonate, and improving the efficiency of ethylene carbonate molecules diffusing into the interlayer domain.

[0015] Preferably, in step [S01], the mixed solvent is obtained by mixing dimethyl sulfoxide and triethylamine in a volume ratio of (20-25):1.

[0016] Preferably, in step [S01], the preparation step of oligomeric polyethylene glycol comprises: taking ethylene glycol monomer, dissolving it, adding a base catalyst, stirring and mixing, and transferring it to a reaction kettle, then adding ethylene oxide dropwise, passing nitrogen, heating to react, releasing the pressure and adjusting the pH, then cooling, filtering with an ion exchange resin, and dehydrating to obtain oligomeric polyethylene glycol;

[0017] The temperature-raising reaction is as follows: raising the system temperature to 100-110° C., adjusting the pressure to 2-2.3 MPa, and treating for 6-8 minutes;

[0018] The mass volume ratio of the added ethylene glycol monomer, base catalyst and ethylene oxide is 5 ml: (0.2-0.3) g: (17.1-18.4) ml.

[0019] By adopting the above technical solution, short-chain polyethylene glycol can be obtained. In the polymerization reaction, ethylene glycol monomer serves as the initiator. Through heating treatment and catalysis by an alkaline catalyst, the ethylene oxide ring is opened to form an oxygen anion intermediate. The intermediate continues to react to form the polyethylene glycol chain growth structure. By adjusting the reaction time and timely quenching the reaction by adjusting the pH, oligomeric polyethylene glycol can be obtained.

[0020] Preferably, the base catalyst is a supported K2O / ZrO2 catalyst, and the preparation steps include the following:

[0021] Take zirconium oxychloride octahydrate, add sodium hexametaphosphate and potassium nitrate, disperse, then add ammonia water drop by drop to adjust the pH, let it stand, take the precipitate, dry it and then roast it.

[0022] By adopting the above technical solution, zirconium oxychloride octahydrate is dissolved in water and then mixed with potassium nitrate under the action of ammonia water to form a sol, and the zirconium ions are further converted into Zr(OH)4 precipitate; finally, after calcination, Zr(OH)4 is sintered into ZrO2; during the calcination process, KNO3 is thermally decomposed to obtain K2O and loaded on the surface of ZrO2, forming alkaline sites, which are used to catalyze the ring-opening polymerization of ethylene oxide.

[0023] Preferably, in step [S01], the acylating agent is one of isobutyryl chloride, 3,3-dimethylbutyryl chloride, and 2-ethylbutyryl chloride;

[0024] The mass volume ratio of the oligomeric polyethylene glycol to the acylating agent is 8 g: (0.4-0.5) ml.

[0025] By adopting the above technical solution, the acylating agent can react with the terminal hydroxyl group of oligomeric polyethylene glycol through a nucleophilic substitution reaction, and the addition of the acid-binding agent triethylamine can promote the forward direction of the substitution reaction. By adjusting the proportion of the reaction raw materials, the oligomeric polyethylene glycol is excessive in the substitution reaction, thereby avoiding the large-scale generation of by-products.

[0026] Preferably, in the step [S02], the mass volume ratio of acylated polyethylene glycol, p-toluenesulfonyl chloride, phthalimide and hydrazine hydrate is 1 g: (1-1.2) g: (0.2-0.3) g: (0.3-0.5) ml.

[0027] By adopting the above technical solution, the acylated polyethylene glycol continues to react with p-toluenesulfonyl chloride to introduce a highly reactive sulfonate group into the molecular chain, and then through nucleophilic substitution of phthalimide and hydrazinolysis reaction of hydrazine hydrate, an amino structure is finally introduced into the end of the acylated polyethylene glycol molecular chain.

[0028] In the second aspect, the present application prepares a prehydrated bentonite anti-seepage material through the above-mentioned preparation process.

[0029] In summary, this application has the following beneficial effects:

[0030] 1. This application improves the water absorption and water retention capacity of calcium-based bentonite through intercalation and the addition of organic composite components. After the interlayer spacing is expanded by ethylene carbonate intercalation, the organic composite component molecules enter the interlayers of the montmorillonite structure in the bentonite through the expanded interlayer structure, adsorb on the montmorillonite layer walls, and capture water molecules through the molecular hydrophilic chain structure, thereby improving the water absorption and water retention capacity of the bentonite anti-seepage material.

[0031] 2. In this application, acylation modification is preferably used to introduce branched short-chain alkyl functional groups at the end of the oligomeric polyethylene glycol molecular chain. Through the steric effect, the migration resistance of the intercalated ethylene carbonate small molecules between the montmorillonite layers is increased, thereby improving the anti-elution ability of the intercalant small molecules.

[0032] 3. The prehydrated bentonite anti-seepage material obtained by the preparation process of the present application has a water absorption rate of ≥5.2 and a water retention rate of ≥63.7%, and can greatly reduce the elution risk of small molecules of the intercalation agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 These are the test results of the water absorption and retention performance of the prehydrated bentonite anti-seepage materials of Examples 1-4 and Comparative Examples 1-2 of the present application.

[0034] Figure 2These are the elution rate test results of prehydrated bentonite anti-seepage materials of Examples 1-4 and Comparative Examples 1-2 of the present application. DETAILED DESCRIPTION

[0035] The following is an example of the preparation of acylated polyethylene glycol:

[0036] Preparation Example 1

[0037] Take 3g of zirconium oxychloride octahydrate, 0.1g of sodium hexametaphosphate and 0.5g of potassium nitrate, add 50ml of deionized water, adjust the magnetic stirring speed to 100rpm, treat for 5min, then add ammonia water with a mass concentration of 14% at a rate of 0.5ml / min to the pH of the system to 9.2. After standing overnight, filter the solid part, dry it in an oven at 100℃ for 2h, place it in a tubular furnace, set the temperature to 450℃, and calcine for 3h to obtain an alkaline catalyst.

[0038] Take 5 ml of ethylene glycol monomer, add 250 ml of deionized water and 0.2 g of base catalyst, stir for 5 minutes to obtain a mixed solution; then set the temperature to 45 ° C, add the mixed solution to the reactor at a rate of 4 ml / min, adjust the magnetic stirring speed to 150 rpm after complete addition, mix for 30 minutes, then add 17.1 ml of ethylene oxide to the reactor at a rate of 1 ml / min, raise the system temperature to 100 ° C under a nitrogen atmosphere, adjust the pressure to 2 MPa, treat for 6 minutes, slowly release the pressure of the reactor to normal pressure, adjust the pH of the system to 5 with 0.5 mol / L hydrochloric acid, then place the reactor in a 4 ° C cold water bath until the system temperature drops to 50 ° C, then add 500 ml of deionized water to the system, adjust the flow rate to 0.5 m / s, use an ion exchange resin column to filter and elute, and the eluted product is dehydrated at 90 ° C under vacuum conditions for 1 hour, and then evaporate the remaining solvent at room temperature under a nitrogen atmosphere to obtain oligomeric polyethylene glycol.

[0039] Take 8g of oligomeric polyethylene glycol, add 75ml of mixed solvent to dissolve, then add 0.4ml of isobutyryl chloride dropwise to the system at a rate of 0.1ml / min, adjust the magnetic stirring speed to 200rpm, the temperature to 30°C, and treat in the dark for 6h, then set the vacuum degree to 0.01MPa and filter under reduced pressure, take the liquid phase and add 0.1mol / L potassium hydroxide to adjust the pH of the system to 7, then add 50ml of icy ether to the system, adjust the magnetic stirring speed to 200rpm, treat for 5min, then filter the solid part, use 20ml of dichloromethane to redissolve it, and evaporate it at 45°C for 2h to obtain acylated polyethylene glycol.

[0040] The mixed solvent is obtained by mixing dimethyl sulfoxide and triethylamine in a volume ratio of 20:1.

[0041] Preparation Example 2

[0042] Take 3g of zirconium oxychloride octahydrate, 0.3g of sodium hexametaphosphate and 0.5g of potassium nitrate, add 50ml of deionized water, adjust the magnetic stirring speed to 100rpm, treat for 20min, then add ammonia water with a mass concentration of 14% at a rate of 0.5ml / min until the pH of the system is 10. After standing overnight, filter and obtain the solid part, dry in an oven at 120℃ for 3h, place in a tubular furnace, set the temperature to 500℃, and calcine for 4h to obtain an alkaline catalyst.

[0043] Take 5 ml of ethylene glycol monomer, add 250 ml of deionized water and 0.3 g of base catalyst, stir for 10 minutes to obtain a mixed solution; then set the temperature to 55 ° C, add the mixed solution to the reactor at a rate of 5 ml / min, adjust the magnetic stirring speed to 150 rpm after the addition is complete, mix for 45 minutes, then add 18.4 ml of ethylene oxide to the reactor at a rate of 2 ml / min, raise the system temperature to 110 ° C under a nitrogen atmosphere, adjust the pressure to 2.3 MPa, treat for 8 minutes, slowly release the pressure of the reactor to normal pressure, adjust the pH of the system to 6 with 0.5 mol / L hydrochloric acid, then place the reactor in a 4 ° C cold water bath until the system temperature drops to 50 ° C, then add 500 ml of deionized water to the system, adjust the flow rate to 0.5 m / s, filter and elute using an ion exchange resin column, dehydrate the eluted product under vacuum conditions at 100 ° C for 2 hours, and then evaporate the remaining solvent at room temperature under a nitrogen atmosphere to obtain oligomeric polyethylene glycol.

[0044] The remaining steps are the same as those in Preparation Example 1.

[0045] Preparation Example 3

[0046] Take 8g of oligomeric polyethylene glycol, add 75ml of mixed solvent to dissolve, then add 0.5ml of 3,3-dimethylbutyryl chloride dropwise to the system at a rate of 0.1ml / min, adjust the magnetic stirring speed to 220rpm, the temperature to 35°C, and treat in the dark for 7h, then set the vacuum degree to 0.02MPa and filter under reduced pressure, take the liquid phase and add 0.1mol / L potassium hydroxide to adjust the pH of the system to 7, then add 50ml of icy ether to the system, adjust the magnetic stirring speed to 200rpm, treat for 8min, then filter the solid part, use 20ml of dichloromethane to redissolve it, and rotary evaporate at 45°C for 2.5h to obtain acylated polyethylene glycol.

[0047] The mixed solvent is obtained by mixing dimethyl sulfoxide and triethylamine in a volume ratio of 24:1.

[0048] The remaining steps are the same as those in Preparation Example 1.

[0049] Preparation Example 4

[0050] Take 5 ml of ethylene glycol monomer, add 250 ml of deionized water and 0.25 g of base catalyst, stir for 8 minutes to obtain a mixed solution; then set the temperature to 50 ° C, add the mixed solution to the reactor at a rate of 4.5 ml / min, adjust the magnetic stirring speed to 150 rpm after the addition is complete, mix for 40 minutes, then add 18 ml of ethylene oxide to the reactor at a rate of 1.5 ml / min, raise the system temperature to 105 ° C under a nitrogen atmosphere, adjust the pressure to 2.2 MPa, and treat for 7 minutes. Then, place the reactor in a 4 ° C cold water bath until the system temperature drops to 50 ° C, slowly release the reactor pressure to normal pressure, then add 500 ml of deionized water to the system, adjust the flow rate to 0.5 m / s, use an ion exchange resin column to filter and elute, and dehydrate the eluted product under vacuum conditions at 95 ° C for 1.5 hours. Then, evaporate the remaining solvent at room temperature under a nitrogen atmosphere to obtain oligomeric polyethylene glycol.

[0051] Take 8g of oligomeric polyethylene glycol, add 75ml of mixed solvent to dissolve, then add 0.4ml of 2-ethylbutyryl chloride dropwise to the system at a rate of 0.1ml / min, adjust the magnetic stirring speed to 200rpm, the temperature to 30°C, and treat in the dark for 6h, then set the vacuum degree to 0.01MPa and filter under reduced pressure, take the liquid phase and add 0.1mol / L potassium hydroxide to adjust the pH of the system to 7, then add 50ml of icy ether to the system, adjust the magnetic stirring speed to 200rpm, treat for 5min, then filter the solid part, use 20ml of dichloromethane to redissolve it, and evaporate it at 45°C for 2h to obtain acylated polyethylene glycol.

[0052] The mixed solvent is obtained by mixing dimethyl sulfoxide and triethylamine in a volume ratio of 25:1.

[0053] The remaining steps are the same as those in Preparation Example 1.

[0054] Example 1

[0055] In this embodiment, the preparation steps of the prehydrated bentonite anti-seepage material are as follows:

[0056] Take 800g of calcium-based bentonite, crush it and pass it through a 150-mesh sieve, then add deionized water at a water-to-material ratio of 1:10, adjust the stirring speed to 300rpm, and process for 10min; then add sodium carbonate to adjust the pH of the system to 8, then add 30g of ethylene carbonate, set the temperature to 60℃, stir at 75rpm for 2h, then add 50g of organic composite components, continue stirring for 2h, then filter and take the solid part, place it in a mixer, add 100g of water glass, mix at 50℃ for 1h, then use the mixed material as the middle layer, flatten it with a roller and cover it on both sides with 120g / m 2The needle-punched non-woven geotextile was then molded on a flat vulcanizer at 2 MPa to obtain an average thickness of 2 mm for the middle layer. It was then dried at 80°C for 2 hours under a nitrogen atmosphere and then cooled overnight.

[0057] In this embodiment, the steps for preparing the organic composite component are as follows:

[0058] Take 10g of acylated polyethylene glycol, add 50ml of acetone and 10ml of triethylamine, disperse for 3min, then add 10g of p-toluenesulfonyl chloride to the system, adjust the magnetic stirring speed to 100rpm, treat for 3h, and then evaporate at 45℃ for 2h, let it stand for 3h, then add the product to a mixture of 40ml of dimethylformamide and 5ml of anhydrous ethanol to redissolve it, then add 2g of phthalimide, adjust the magnetic stirring speed to 200rpm, add 0.5mol / L potassium hydroxide 2ml to the system under a nitrogen atmosphere, adjust the temperature to 60℃, treat for 1h, then increase the reaction temperature to 105℃ and continue to treat for 6h, then evaporate the solvent under reduced pressure, add 75ml of anhydrous ethanol and 3ml of hydrazine hydrate to the system, reflux for 4h, and then evaporate the solvent under reduced pressure again, then add 30ml of dichloromethane, filter the impurities and evaporate the solvent under reduced pressure again, then add 20ml of anhydrous ether to the system, stir for 2min, filter the precipitate, and dry at 35℃ to obtain an organic composite component.

[0059] Among them, calcium-based bentonite (montmorillonite 72wt%) was provided by Shijiazhuang Borui Building Materials Co., Ltd.

[0060] In this example, the acylated polyethylene glycol was prepared by Preparation Example 1.

[0061] Example 2

[0062] In this embodiment, the preparation steps of the prehydrated bentonite anti-seepage material are as follows:

[0063] Take 850g of calcium bentonite, crush it and pass it through a 150-mesh sieve, then add deionized water at a water-to-material ratio of 1:12, adjust the stirring speed to 350rpm, and process for 20min; then add sodium carbonate to adjust the pH of the system to 9, then add 40g of ethylene carbonate, set the temperature to 75℃, stir at 80rpm for 3h, then add 60g of organic composite components, continue stirring for 2.5h, then filter and take the solid part, place it in a mixer, add 100g of water glass, mix at 65℃ for 1.5h, then use the mixed material as the middle layer, flatten it with a roller and cover it on both sides with 120g / m 2 The needle-punched non-woven geotextile was then molded on a flat vulcanizer at 3 MPa to obtain an average thickness of 2 mm for the middle layer. It was then dried at 90°C for 2 hours under a nitrogen atmosphere and then cooled overnight.

[0064] In this embodiment, the steps for preparing the organic composite component are as follows:

[0065] Take 10g of acylated polyethylene glycol, add 50ml of acetone and 10ml of triethylamine, disperse for 5min, then add 11g of p-toluenesulfonyl chloride to the system, adjust the magnetic stirring speed to 125rpm, treat for 4h, evaporate at 45℃ for 2h, let stand for 3h, then add the product to a mixture of 40ml of dimethylformamide and 5ml of anhydrous ethanol to redissolve, then add 3g of phthalimide, adjust the magnetic stirring speed to 200rpm, add 2ml of 0.5mol / L potassium hydroxide to the system under a nitrogen atmosphere, adjust the temperature to 60℃, treat for 1.5h, then increase the reaction temperature to 105℃, continue to treat for 7h, then evaporate the solvent under reduced pressure, add 75ml of anhydrous ethanol and 4ml of hydrazine hydrate to the system, reflux for 5h, and then evaporate the solvent under reduced pressure again, then add 30ml of dichloromethane, filter impurities and evaporate the solvent under reduced pressure again, then add 20ml of anhydrous ether to the system, stir for 3min, filter the precipitate, and dry at 35℃ to obtain an organic composite component.

[0066] Among them, calcium-based bentonite (montmorillonite 72wt%) was provided by Shijiazhuang Borui Building Materials Co., Ltd.

[0067] In this example, the acylated polyethylene glycol was prepared by Preparation Example 2.

[0068] Example 3

[0069] In this embodiment, the preparation steps of the prehydrated bentonite anti-seepage material are as follows:

[0070] Take 900g of calcium bentonite, crush it and pass it through a 150-mesh sieve, then add deionized water at a water-to-material ratio of 1:15, adjust the stirring speed to 500rpm, and process for 30min; then add sodium carbonate to adjust the pH of the system to 9, then add 50g of ethylene carbonate, set the temperature to 80℃, stir at 100rpm for 4h, then add 80g of organic composite components, continue stirring for 3h, then filter and take the solid part, place it in a mixer, add 120g of water glass, mix at 70℃ for 2h, then use the mixed material as the middle layer, flatten it with a roller and cover it on both sides with 120g / m 2 The needle-punched non-woven geotextile was then molded on a flat vulcanizer at 5 MPa to obtain an average thickness of 2 mm for the middle layer. It was then dried at 80°C for 2 hours under a nitrogen atmosphere and then cooled overnight.

[0071] In this embodiment, the steps for preparing the organic composite component are as follows:

[0072] Take 10g of acylated polyethylene glycol, add 50ml of acetone and 10ml of triethylamine, disperse for 5min, then add 12g of p-toluenesulfonyl chloride to the system, adjust the magnetic stirring speed to 150rpm, treat for 4h, and then evaporate at 45℃ for 2.5h, let it stand for 4h, then add the product to a mixture of 40ml of dimethylformamide and 5ml of anhydrous ethanol to redissolve it, then add 3g of phthalimide, adjust the magnetic stirring speed to 200rpm, add 2ml of 0.5mol / L potassium hydroxide to the system under a nitrogen atmosphere, adjust the temperature to 60℃, treat for 2h, then increase the reaction temperature to 110℃ and continue to treat for 8h, then evaporate the solvent under reduced pressure, add 75ml of anhydrous ethanol and 5ml of hydrazine hydrate to the system, reflux for 5h, and then evaporate the solvent under reduced pressure again, then add 30ml of dichloromethane, filter the impurities and evaporate the solvent under reduced pressure again, then add 20ml of anhydrous ether to the system, stir for 3min, filter the precipitate, and dry at 35℃ to obtain an organic composite component.

[0073] Among them, calcium-based bentonite (montmorillonite 72wt%) was provided by Shijiazhuang Borui Building Materials Co., Ltd.

[0074] In this example, the acylated polyethylene glycol was prepared by Preparation Example 3.

[0075] Example 4

[0076] The only difference between this example and Example 1 is that the acylated polyethylene glycol is prepared by Preparation Example 4.

[0077] Among them, calcium-based bentonite (montmorillonite 72wt%) was provided by Shijiazhuang Borui Building Materials Co., Ltd.

[0078] The remaining steps are the same as those in Example 1.

[0079] Comparative Example 1

[0080] The only difference between this comparative example and Example 1 is that the steps for preparing the organic composite component are as follows:

[0081] Take 10g of oligomeric polyethylene glycol, add 50ml of acetone and 10ml of triethylamine, disperse for 3min, then add 10g of p-toluenesulfonyl chloride to the system, adjust the magnetic stirring speed to 100rpm, treat for 3h, rotary evaporate at 45℃ for 2h, let stand for 3h, then add the product to a mixture of 40ml of dimethylformamide and 5ml of anhydrous ethanol to redissolve, then add 2g of phthalimide, adjust the magnetic stirring speed to 200rpm, add 2ml of 0.5mol / L potassium hydroxide to the system under a nitrogen atmosphere, adjust the temperature to 60℃, treat for 1h, then increase the reaction temperature to 105℃ and continue to treat for 6h, then evaporate the solvent under reduced pressure, add 75ml of anhydrous ethanol and 3ml of hydrazine hydrate to the system, reflux for 4h, then evaporate the solvent under reduced pressure again, then add 30ml of dichloromethane, filter impurities and evaporate the solvent under reduced pressure again, then add 20ml of anhydrous ether to the system, stir for 2min, filter the precipitate, and dry at 35℃ to obtain an organic composite product.

[0082] The remaining steps are the same as those in Example 1.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that an equal amount of polyethylene glycol is used instead of the organic composite component.

[0085] Among them, polyethylene glycol (model: PEG-6000) was provided by Shandong Yangdao Biotechnology Co., Ltd.

[0086] The remaining steps are the same as those in Example 1.

[0087] Performance testing

[0088] Water absorption and retention performance test

[0089] Take the prehydrated bentonite anti-seepage materials of Examples 1-4 and Comparative Examples 1-2, and cut them into 20 cm × 25 cm sizes to obtain test samples. Record the mass of each group of test samples at this time, recorded as m1; prepare a 60 cm × 49 cm × 34 cm test box, inject tap water until the water level is 15 cm and stop, then place each group of test samples in the test box, let them stand for 3 hours, then take them out, drain the water, and record the mass of each group of test samples at this time, recorded as m2; then transfer them to a 50°C oven and dry them for 4 hours, and record the mass of each group of test samples at this time, recorded as m3.

[0090] According to the formula:

[0091] Water absorption rate = (m2-m1) / m1;

[0092] Water retention rate = [(m3-m1) / (m2-m1)]×100%.

[0093] Calculate the water absorption rate and water retention rate of each group of test samples. Each group of test samples was tested 3 times and the average value was taken as the final data. The test results are as follows: Figure 1 shown.

[0094] Elution rate test

[0095] The prehydrated bentonite anti-seepage materials of Examples 1-4 and Comparative Examples 1-2 were cut into test discs with a diameter of 55 mm, placed in a Buchner funnel with an inner diameter of 55 mm, and eluted with tap water at an injection rate of 5 ml / min. After the filtrate volume reached 100 ml, the filtrate was recovered and the injection rate was changed to 20 ml / min to elute the test disc twice. After that, the injection rate was maintained, and the test disc was eluted 10 times. The filtrate was collected and concentrated at 90°C for 2 h to obtain a concentrated filtrate.

[0096] Referring to HG / T5391-2018, the ethylene carbonate content of the concentrated filtrate of Example 1-4 and Comparative Example 1-2 was tested, and the elution rate of ethylene carbonate in each group was calculated. The test results are as follows: Figure 2 shown.

[0097] Analyze Examples 1-4 and Comparative Examples 1-2 and combine Figure 1 As can be seen, the prehydrated bentonite anti-seepage material prepared using the embodiment scheme has higher water absorption and retention performance than the comparative example scheme, indicating that the embodiment scheme has superior water absorption and water retention capabilities. In all test groups, the solution of comparative example 1 does not undergo acylation treatment of the oligomeric polyethylene glycol, and the combination of the raw material components does not significantly improve the material's water absorption and water retention properties, but the overall water absorption and retention performance is still better than that of comparative example 2.

[0098] Analyze Examples 1-4 and Comparative Examples 1-2 and combine Figure 1-2 As can be seen, the elution rate of the Example solution exhibits a trend similar to the water absorption and retention test data, demonstrating that the Example solution not only improves the material's water absorption and retention properties, but also enhances the elution resistance of the small molecule intercalant. Among all groups, the ethylene carbonate elution in Comparative Example 2 was the most severe. This is because the high-molecular-weight polyethylene glycol chain segments used in Comparative Example 2 are too long, making it difficult for them to penetrate the montmorillonite interlayers of the bentonite during the intercalation stage. The small molecule intercalant, ethylene carbonate, is easily removed from the montmorillonite interlayers by water scouring, ultimately resulting in a significant increase in the ethylene carbonate elution rate in Comparative Example 2.

[0099] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for preparing a prehydrated bentonite anti-seepage material, characterized in that: The invention is obtained by mixing the following raw materials in parts by weight: 80-90 parts of calcium bentonite, 10-12 parts of a binder, 5-8 parts of an organic composite component, and 3-5 parts of ethylene carbonate. The preparation steps include the following: Calcium-based bentonite is crushed and sieved, then dispersed with water, the pH is adjusted, and then ethylene carbonate is added. The mixture is heated and stirred, and then the organic composite component is added and the mixture is further treated. The solid portion is filtered and a binder is added. The mixture is then mixed, coated, and molded, and cooled to obtain the product. The steps for preparing the organic composite component include the following: [S01] dissolving oligomeric polyethylene glycol in a mixed solvent, then dropwise adding an acylating agent, reacting in the dark, then filtering under reduced pressure, adjusting the pH of the liquid phase, and sequentially separating by precipitation and rotary evaporation to obtain acylated polyethylene glycol; [S02] Acylated polyethylene glycol is dispersed, and then p-toluenesulfonyl chloride is added. After the reaction, the mixture is rotary evaporated and then redissolved. Phthalimide is added, and potassium hydroxide solution is added dropwise. The mixture is heated, and then the solvent is removed, the mixture is redissolved, hydrazine hydrate is added, and the mixture is refluxed and purified to obtain the product.

2. The process for preparing a prehydrated bentonite anti-seepage material according to claim 1, wherein: The heating and stirring process is as follows: setting the temperature to 60-80° C., adjusting the stirring speed to 75-100 rpm, and stirring for 2-4 hours.

3. The preparation process of a prehydrated bentonite anti-seepage material according to claim 1, characterized in that: In the step [S01], the preparation step of oligomeric polyethylene glycol includes: taking ethylene glycol monomer, dissolving it, adding a base catalyst, stirring and mixing, and transferring it to a reactor, then adding ethylene oxide dropwise, passing nitrogen, heating to react, adjusting the pH after pressure release, then cooling, filtering with an ion exchange resin, and dehydrating to obtain oligomeric polyethylene glycol.

4. The process for preparing a prehydrated bentonite anti-seepage material according to claim 3, wherein: The mass volume ratio of the added ethylene glycol monomer, the base catalyst and the ethylene oxide is 5 ml: (0.2-0.3) g: (17.1-18.4) ml; the base catalyst is a supported K2O / ZrO2 catalyst.

5. The preparation process of a prehydrated bentonite anti-seepage material according to claim 3, characterized in that: The temperature-raising reaction is as follows: raising the system temperature to 100-110° C., adjusting the pressure to 2-2.3 MPa, and treating for 6-8 minutes.

6. The process for preparing a prehydrated bentonite anti-seepage material according to claim 1, wherein: In the step [S01], the mixed solvent is obtained by mixing dimethyl sulfoxide and triethylamine in a volume ratio of (20-25):

1.

7. The process for preparing a prehydrated bentonite anti-seepage material according to claim 1, wherein: In the step [S01], the acylating agent is one of isobutyryl chloride, 3,3-dimethylbutyryl chloride, and 2-ethylbutyryl chloride.

8. The process for preparing a prehydrated bentonite anti-seepage material according to claim 1, wherein: In the step [S01], the mass volume ratio of oligomeric polyethylene glycol to acylating agent is 8 g: (0.4-0.5) ml.

9. The process for preparing a prehydrated bentonite anti-seepage material according to claim 1, wherein: In the step [S02], the mass volume ratio of acylated polyethylene glycol, p-toluenesulfonyl chloride, phthalimide and hydrazine hydrate is 1 g: (1-1.2) g: (0.2-0.3) g: (0.3-0.5) ml.

10. A prehydrated bentonite anti-seepage material prepared by the preparation process according to any one of claims 1 to 9.

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