Pseudo-boehmite with strong adsorption performance and preparation method thereof

Abstract

The invention discloses a pseudo-boehmite with strong adsorption performance and a preparation method thereof, and belongs to the technical field of pseudo-boehmite preparation. The pseudo-boehmite with strong adsorption performance is composed of the following components in parts by weight: 28-33 parts of aluminum sulfate, 55-68 parts of sodium aluminate, 3-5 parts of pore expanders, and 2-4 parts of imidazole-based dispersants, wherein the pore expander is obtained by reacting β-cyclodextrin, maleic acid and acrylic acid, and the imidazole-based dispersant is obtained by reacting imidazole, 1,2-dibromoethane and 1-bromopentadecane. By adding the pore expander and the imidazole dispersant during the preparation process, the purity, specific surface area, pore volume and adsorption performance of the pseudo-boehmite can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pseudo-boehmite preparation, and in particular relates to pseudo-boehmite with strong adsorption performance and a preparation method thereof. Background Art

[0002] Pseudo-boehmite, also known as monohydrated aluminum oxide or pseudo-boehmite, is non-toxic, tasteless, odorless, and white colloid or powder. It has high crystal purity, good peptization performance, strong adhesion, high specific surface area, large pore volume and other characteristics, making it have broad application prospects in many fields.

[0003] First, pseudo-boehmite plays an important role in the field of catalysts. It can be used as a binder for semi-synthetic rare earth Y-type molecular sieve cracking catalysts, as well as alcohol dehydration catalysts for ethylene and ethylene oxide catalysts. In addition, through specific calcination temperature treatment, pseudo-boehmite can also be converted into γ-Al2O3 and nano-sized α-Al2O3, which are widely used as catalyst carriers, catalysts and adsorbents. Secondly, pseudo-boehmite is also widely used in the field of materials science. It can be used as a binder for aluminum silicate refractory fibers, as well as coating additives, high-grade ceramics, high-efficiency catalysts for petrochemicals, submicron / nano-sized grinding materials and polishing materials, cosmetic fillers and inorganic membrane materials. These applications require pseudo-boehmite to have excellent adsorption properties, high purity and stability.

[0004] Patent CN 110652957 B discloses a preparation method of pseudo-boehmite microspheres and its application, the preparation method comprising the following steps: 1) mixing aluminum sulfate, an amide precipitant and water to obtain a reaction solution; 2) placing the reaction solution in a hydrothermal reactor for hydrothermal reaction to obtain pseudo-boehmite microspheres. The method is simple in preparation of pseudo-boehmite, with mild reaction conditions, and the prepared pseudo-boehmite microspheres have excellent adsorption performance for azo dye Congo red, but the purity, stability and adsorption performance of the pseudo-boehmite prepared by the method still have room for improvement. Summary of the invention

[0005] The object of the present invention is to provide a pseudo-boehmite with strong adsorption performance and a preparation method thereof, so as to solve the technical problems of low stability, low purity and poor adsorption performance of the pseudo-boehmite in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention provides pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 28-33 parts of aluminum sulfate, 55-68 parts of sodium aluminate, 3-5 parts of pore expanders, and 2-4 parts of imidazole-based dispersants, wherein the pore expander is obtained by reacting beta-cyclodextrin, maleic acid and acrylic acid, and the imidazole-based dispersant is obtained by reacting imidazole, 1,2-dibromoethane and 1-bromopentadecane.

[0008] Preferably, the method for preparing the pore expanding agent comprises the following steps:

[0009] Q1: Dissolve β-cyclodextrin in distilled water, discard the upper liquid after recrystallization, dry the obtained crystals, and repeat the operation to obtain high-purity β-cyclodextrin;

[0010] Q2: Add high-purity β-cyclodextrin, maleic acid, sodium hypophosphite and 4-methoxyphenol into a container, stir and mix, add distilled water and stir evenly, then place the container in a constant temperature air drying oven for reaction to obtain a complex ester;

[0011] Q3: Add the complex ester and acrylic acid into a container, mix well, add double distilled water, and then stir in a water bath until all the solids are dissolved. After adding potassium persulfate, place the container in a constant temperature water bath to react to obtain a reaction mixture, transfer it to a beaker, add ethanol to the beaker while stirring to precipitate a polymer, collect the solid, wash, filter, and dry to obtain a pore expander.

[0012] In the above process, the pore expander is prepared by chemical method, potassium persulfate is used as an initiator, a free radical chain reaction is initiated, and the complex ester and acrylic acid are polymerized. The persulfate ions are heated in an aqueous solution to decompose into sulfate radicals, and the sulfate radicals react with water molecules to generate hydroxyl radicals. The hydroxyl radicals can attack the unsaturated double bonds in the complex ester and acrylic acid, and initiate a vinyl polymerization reaction. The complex ester and acrylic acid are continuously added to the initiator chain until the free radicals are connected to form a single bond, and the chain reaction is terminated to obtain the pore expander.

[0013] Preferably, in Q1, the dosage ratio of β-cyclodextrin and distilled water is (250-300) g: (1000-1200) mL, the temperature of distilled water is 80-85°C, the recrystallization temperature is 3-5°C, the drying temperature is 85-95°C, the time is 6-8h, and the operation is repeated 2-4 times; in Q2, the molar ratio of high-purity β-cyclodextrin, maleic acid, sodium hypophosphite, 4-methoxyphenol and distilled water is (0.8-1.2): (4-4.4): (2-2.1): (0.1-0.15): (50-55), the reaction temperature is 110-120°C, and the reaction time is 3-4h.

[0014] Preferably, in Q3, the dosage ratio of complex ester, acrylic acid, double distilled water, potassium persulfate and ethanol is (3-4) g: (3-4) g: (10-12) mL: (0.005-0.006) g: (80-85) mL, the water bath temperature is 50-55°C, the water bath reaction temperature is 70-80°C, the time is 2-4h, the volume fraction of ethanol is 95vt%, and the solid is washed with anhydrous ethanol 3-5 times until the solid becomes a uniform powdery solid, and the drying temperature is 60-70°C, and the time is 6-8h.

[0015] Preferably, the preparation method of the imidazole-based dispersant comprises the following steps:

[0016] S1: Add imidazole and 1,2-dibromoethane into a container, then add sodium hydroxide solution and isopropanol, stir the mixture thoroughly, and then put the container into a microwave reactor. After the reaction is completed, pour the product into a separatory funnel, let it stand, and take the upper liquid to cool;

[0017] S2: adding 1-bromopentadecane to the cooled upper liquid, mixing and stirring, and transferring to a microwave reactor. After the reaction is completed, distilling under reduced pressure and drying to obtain a crude imidazole product;

[0018] S3: Dissolve the crude imidazole product in ethyl acetate, heat in a water bath, condense and reflux, and purify by recrystallization. Repeat the operation to obtain an imidazole dispersant.

[0019] In the above process, a microwave-assisted synthesis method is used, imidazole, 1,2-dibromoethane and 1-bromopentadecane are used as raw materials, and a crude imidazole product is synthesized by a two-step synthesis method, and then an imidazole-based dispersant is obtained by purification. The reaction equation of the imidazole dispersant is:

[0020]

[0021] The results of mass spectrometry analysis were: m / z: 745.42 (100.0%), 747.42 (57.3%), 743.42 (51.2%), 746.42 (43.3%), 744.42 (21.8%), 748.42 (20.5%), 745.43 (4.4%), 749.42 (4.3%), 748.43 (1.1%).

[0022] Preferably, in S1, the molar ratio of imidazole to 1,2-dibromoethane is (1.8-2.2):(0.9-1.1), the volume fraction of the sodium hydroxide solution is 50vt%, the power of the microwave reactor is 300-500W, the reaction time is 5-9min, the reaction temperature is 55-65°C, and the standing time is 7-10h.

[0023] Preferably, in S2, the molar ratio of the upper liquid to 1-bromopentadecane is 1:(1.9-2.2), the mixing time is 10-20 min, the microwave reactor power is 400-600 W, the reaction time is 4-8 min, the reaction temperature is 50-60°C, the reduced pressure distillation temperature is 60-65°C, the drying temperature is 80-90°C, and the time is 7-9h.

[0024] Preferably, in S3, the usage ratio of the crude imidazole product and ethyl acetate is (8-10) g: (20-30) mL, the water bath heating temperature is 75-80° C., the condensation reflux time is 3-5 min, and the operation is repeated 3-5 times.

[0025] Preferably, the method for preparing the pseudo-boehmite with strong adsorption performance comprises the following steps:

[0026] Step (1): adding aluminum sulfate solution, sodium aluminate solution and pore-enlarging agent into a four-necked flask with a constant temperature water bath and a stirring device through a peristaltic pump, and controlling the dropping rate;

[0027] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, form gel, stand for aging, filter, wash, and dry to obtain pseudo-boehmite with strong adsorption properties.

[0028] Preferably, in the step (1), the concentration of the aluminum sulfate solution is 150 g / L, the concentration of the sodium aluminate solution is 200 g / L, the water bath temperature is 58-62° C., the stirring speed is 80-100 rpm, the dropping speed of the aluminum sulfate solution is 8-10 mL / min, and the dropping speed of the sodium aluminate solution is 8-10 mL / min; in the step (2), after gelation, the pH is adjusted to 10-11, the static aging temperature is 90-100° C., the time is 3-5 h, the solution is washed with deionized water, and the drying temperature is 120-140° C., and the time is 12-14 h.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The present invention first uses β-cyclodextrin, maleic acid and acrylic acid as raw materials, and synthesizes a pore expander under the condition of potassium persulfate as an initiator, and then uses imidazole, 1,2-dibromoethane and 1-bromopentadecane as raw materials to synthesize an imidazole-based dispersant. In the process of preparing pseudo-boehmite, adding the pore expander and the imidazole dispersant can effectively improve the stability, purity and adsorption performance of the pseudo-boehmite.

[0031] 2. The present invention uses β-cyclodextrin, maleic acid and acrylic acid as raw materials to synthesize a pore-enlarging agent, and adds the pore-enlarging agent to the preparation process of pseudo-boehmite, which can effectively improve the adsorption performance of pseudo-boehmite. The pore-enlarging agent can not only form pores inside the pseudo-boehmite, increase its specific surface area, so that more adsorbate molecules can contact and adsorb on the surface, and improve the physical adsorption capacity, but also improve the pore structure to make it more uniform and orderly, which is helpful to improve the adsorption efficiency and selectivity. The β-cyclodextrin used in the pore-enlarging agent is a biodegradable polysaccharide, and the distilled water and ethanol used reduce environmental pollution and waste disposal problems, so that the obtained pore-enlarging agent Green and environmentally friendly; at the same time, β-cyclodextrin, as a cyclic oligosaccharide, has a unique cavity structure and can include and stabilize other molecules. Butylene glycol, as a polyunsaturated carboxylic acid, undergoes esterification reaction with β-cyclodextrin to form a complex ester. The complex ester can be used as a template or directing agent to guide pseudo-boehmite to form a specific pore structure. The groups in the complex ester can also be introduced into the surface or pores of pseudo-boehmite, giving it more adsorption functions and selectivity, and achieving higher adsorption efficiency and stability through chemical adsorption. The synergistic effect of physical adsorption and chemical adsorption further enhances the adsorption performance of pseudo-boehmite.

[0032] 3. The present invention uses imidazole, 1,2-dibromoethane and 1-bromopentadecane as raw materials to synthesize an imidazole-based dispersant, and adds the imidazole-based dispersant to the preparation process of pseudo-boehmite, which can effectively improve the stability and purity of the pseudo-boehmite. The imidazole-based dispersant can be adsorbed on the surface of the pseudo-boehmite particles by physical or chemical means to form a charged molecular layer, thereby generating an electrostatic repulsion effect, effectively preventing the agglomeration between the particles, thereby maintaining the stable dispersion of the pseudo-boehmite particles in the system. The long chain structure of the imidazole-based dispersant forms a physical barrier on the surface of the pseudo-boehmite particles, effectively preventing direct contact and agglomeration between the particles, and further improving the stability of the pseudo-boehmite; the generated electrostatic repulsion and physical barrier can also effectively prevent the adsorption of other impurity particles in the system, which helps to maintain the purity of the pseudo-boehmite and reduce the influence of impurities. The imidazole-based dispersant contains interacts with the pseudo-boehmite to improve its stability at high temperatures, which helps to reduce the thermal decomposition and oxidation of the pseudo-boehmite during the preparation process and maintain its high purity. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing a pore expanding agent, comprising the following steps:

[0036] Q1: Dissolve 275g of β-cyclodextrin in 1100mL of distilled water at 85°C, recrystallize at 4°C, discard the upper liquid, dry the obtained crystals at 85°C for 8h, repeat the operation 3 times to obtain high-purity β-cyclodextrin;

[0037] Q2: 5.35 g of high-purity β-cyclodextrin, 2.31 g of maleic acid, 1.025 g of sodium hypophosphite and 0.0625 mL of 4-methoxyphenol were added to a container, stirred and mixed, and then 4.46 mL of distilled water was added and stirred evenly. Then, the container was placed in a constant temperature blast drying oven at 120° C. to react for 4 hours to obtain a complex ester;

[0038] Q3: Add 3.5g of complex ester and 3.5g of acrylic acid into a container, mix well, add 11mL of double distilled water, and then stir in a 55℃ water bath until all the solids are dissolved. After adding 0.005g of potassium persulfate, place the container in a constant temperature water bath at 80℃ to react for 4h to obtain a reaction mixture, transfer it to a beaker, add 82.5mL of 95vt% ethanol into the beaker while stirring to precipitate the polymer, collect the solid, wash it 3 times with anhydrous ethanol until the solid becomes a uniform powdery solid, filter it, and dry it at 70℃ for 8h to obtain a pore expander.

[0039] This embodiment provides a method for preparing an imidazole-based dispersant, comprising the following steps:

[0040] S1: 1.505 mL of imidazole and 1.11 mL of 1,2-dibromoethane were added to the container, followed by addition of 50% by volume of sodium hydroxide solution and isopropanol, the mixture was fully stirred, and then the container was placed in a microwave reactor, the microwave reactor power was 400 W, the reaction time was 8 min, and the reaction temperature was 60 ° C. After the reaction was completed, the product was poured into a separatory funnel, allowed to stand for 10 h, and the upper liquid was cooled;

[0041] S2: Add 4.86 mL of 1-bromopentadecane to 1 g of the cooled upper liquid, stir for 20 min, and then transfer to a microwave reactor. The microwave reactor power is 500 W, the reaction time is 6 min, and the reaction temperature is 55°C. After the reaction is completed, distill under reduced pressure at 65°C and dry at 90°C for 9 h to obtain a crude imidazole product;

[0042] S3: Dissolve 9 g of the crude imidazole product in 25 mL of ethyl acetate, heat in a water bath at 80°C, condense and reflux for 5 min, and purify by recrystallization. Repeat the operation 5 times to obtain an imidazole dispersant.

[0043] This embodiment discloses a pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 30.5 parts of aluminum sulfate, 61.5 parts of sodium aluminate, 4 parts of pore expander, and 3 parts of imidazole-based dispersant.

[0044] This embodiment discloses a method for preparing pseudo-boehmite with strong adsorption performance, comprising the following steps:

[0045] Step (1): adding 150 g / L aluminum sulfate solution, 200 g / L sodium aluminate solution and a pore-enlarging agent into a four-necked flask in a 62° C. constant temperature water bath and equipped with a stirring device through a peristaltic pump, the stirring speed is 90 rpm, the dropping speed of the aluminum sulfate solution is 9 mL / min, and the dropping speed of the sodium aluminate solution is 8 mL / min;

[0046] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and then the pH is adjusted to 10.5, and the solution is aged at 100°C for 5 hours, filtered, washed with deionized water, and dried at 140°C for 14 hours to obtain pseudo-boehmite with strong adsorption properties.

[0047] Example 2

[0048] This embodiment provides a method for preparing a pore expanding agent, comprising the following steps:

[0049] Q1: Dissolve 250g of β-cyclodextrin in 1000mL of distilled water at 85°C, recrystallize at 4°C, discard the upper liquid, dry the obtained crystals at 85°C for 8h, repeat the operation 3 times to obtain high-purity β-cyclodextrin;

[0050] Q2: 4.28 g of high-purity β-cyclodextrin, 2.19 g of maleic acid, 1 g of sodium hypophosphite and 0.05 mL of 4-methoxyphenol were added to a container, stirred and mixed, and then 4.25 mL of distilled water was added and stirred evenly. Then, the container was placed in a constant temperature blast drying oven at 120° C. to react for 4 hours to obtain a complex ester;

[0051] Q3: Add 3g of complex ester and 3g of acrylic acid into a container, mix well, add 10mL of double distilled water, and then stir in a 55℃ water bath until all the solids are dissolved. After adding 0.006g of potassium persulfate, place the container in a constant temperature water bath at 80℃ to react for 4h to obtain a reaction mixture, transfer it to a beaker, add 80mL of 95vt% ethanol into the beaker while stirring to precipitate the polymer, collect the solid, wash it 3 times with anhydrous ethanol until the solid becomes a uniform powdery solid, filter it, and dry it at 70℃ for 8h to obtain a pore expander.

[0052] This embodiment provides a method for preparing an imidazole-based dispersant, comprising the following steps:

[0053] S1: 1.35 mL of imidazole and 1 mL of 1,2-dibromoethane were added to a container, followed by addition of 50% by volume of sodium hydroxide solution and isopropanol, the mixture was fully stirred, and then the container was placed in a microwave reactor with a power of 400 W, a reaction time of 8 min, and a reaction temperature of 60 ° C. After the reaction was completed, the product was poured into a separatory funnel, allowed to stand for 10 h, and the upper layer of liquid was cooled;

[0054] S2: Add 4.51 mL of 1-bromopentadecane to 1 g of the cooled upper liquid, mix and stir for 20 min, then transfer to a microwave reactor. The microwave reactor power is 500 W, the reaction time is 6 min, and the reaction temperature is 55°C. After the reaction is completed, distill under reduced pressure at 65°C and dry at 90°C for 9 h to obtain a crude imidazole product;

[0055] S3: Dissolve 8 g of the crude imidazole product in 20 mL of ethyl acetate, heat in a water bath at 80°C, condense and reflux for 5 min, and purify by recrystallization. Repeat the operation 5 times to obtain an imidazole dispersant.

[0056] This embodiment discloses a pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 28 parts of aluminum sulfate, 55 parts of sodium aluminate, 3 parts of pore expander, and 2 parts of imidazole-based dispersant.

[0057] This embodiment discloses a method for preparing pseudo-boehmite with strong adsorption performance, comprising the following steps:

[0058] Step (1): adding 150 g / L aluminum sulfate solution, 200 g / L sodium aluminate solution and a pore-enlarging agent into a four-necked flask in a 62° C. constant temperature water bath and equipped with a stirring device through a peristaltic pump, the stirring speed is 90 rpm, the dropping speed of the aluminum sulfate solution is 9 mL / min, and the dropping speed of the sodium aluminate solution is 8 mL / min;

[0059] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and then the pH is adjusted to 10.5, and the solution is aged at 100°C for 5 hours, filtered, washed with deionized water, and dried at 140°C for 14 hours to obtain pseudo-boehmite with strong adsorption properties.

[0060] Example 3

[0061] This embodiment provides a method for preparing a pore expanding agent, comprising the following steps:

[0062] Q1: Dissolve 300g of β-cyclodextrin in 1200mL of distilled water at 85°C, recrystallize at 4°C, discard the upper liquid, dry the obtained crystals at 85°C for 8h, repeat the operation 3 times to obtain high-purity β-cyclodextrin;

[0063] Q2: 6.42 g of high-purity β-cyclodextrin, 2.41 g of maleic acid, 1.05 g of sodium hypophosphite and 0.075 mL of 4-methoxyphenol were added to a container, stirred and mixed, and then 4.67 mL of distilled water was added and stirred evenly. Then, the container was placed in a constant temperature blast drying oven at 120° C. to react for 4 hours to obtain a complex ester;

[0064] Q3: Add 4g of complex ester and 4g of acrylic acid into a container, mix well, add 12mL of double distilled water, and then stir in a 55℃ water bath until all the solids are dissolved. After adding 0.005g of potassium persulfate, place the container in a constant temperature water bath at 80℃ to react for 4h to obtain a reaction mixture, transfer it to a beaker, add 85mL of 95vt% ethanol into the beaker while stirring to precipitate the polymer, collect the solid, wash it 3 times with anhydrous ethanol until the solid becomes a uniform powdery solid, filter it, and dry it at 70℃ for 8h to obtain a pore expander.

[0065] This embodiment provides a method for preparing an imidazole-based dispersant, comprising the following steps:

[0066] S1: 1.66 mL of imidazole and 1.22 mL of 1,2-dibromoethane were added to the container, followed by addition of 50% by volume of sodium hydroxide solution and isopropanol, the mixture was fully stirred, and then the container was placed in a microwave reactor with a power of 400 W, a reaction time of 8 min, and a reaction temperature of 60 ° C. After the reaction was completed, the product was poured into a separatory funnel, allowed to stand for 10 h, and the upper layer of liquid was cooled;

[0067] S2: Add 5.22 mL of 1-bromopentadecane to 1 g of the cooled upper liquid, mix and stir for 20 min, then transfer to a microwave reactor. The microwave reactor power is 500 W, the reaction time is 6 min, and the reaction temperature is 55° C. After the reaction is completed, distill under reduced pressure at 65° C. and dry at 90° C. for 9 h to obtain a crude imidazole product;

[0068] S3: Dissolve 10 g of the crude imidazole product in 30 mL of ethyl acetate, heat in a water bath at 80°C, condense and reflux for 5 min, and purify by recrystallization. Repeat the operation 5 times to obtain an imidazole dispersant.

[0069] This embodiment discloses a pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 33 parts of aluminum sulfate, 68 parts of sodium aluminate, 5 parts of pore expander, and 4 parts of imidazole-based dispersant.

[0070] This embodiment discloses a method for preparing pseudo-boehmite with strong adsorption performance, comprising the following steps:

[0071] Step (1): adding 150 g / L aluminum sulfate solution, 200 g / L sodium aluminate solution and a pore-enlarging agent into a four-necked flask in a 62° C. constant temperature water bath and equipped with a stirring device through a peristaltic pump, the stirring speed is 90 rpm, the dropping speed of the aluminum sulfate solution is 9 mL / min, and the dropping speed of the sodium aluminate solution is 8 mL / min;

[0072] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and then the pH is adjusted to 10.5, and the solution is aged at 100°C for 5 hours, filtered, washed with deionized water, and dried at 140°C for 14 hours to obtain pseudo-boehmite with strong adsorption properties.

[0073] Example 4

[0074] This embodiment provides a method for preparing a pore expanding agent, comprising the following steps:

[0075] Q1: Dissolve 280g of β-cyclodextrin in 1050mL of distilled water at 85°C, recrystallize at 4°C, discard the upper liquid, dry the obtained crystals at 85°C for 8h, repeat the operation 3 times to obtain high-purity β-cyclodextrin;

[0076] Q2: 4.87 g of high-purity β-cyclodextrin, 2.27 g of maleic acid, 1.01 g of sodium hypophosphite and 0.055 mL of 4-methoxyphenol were added to a container, stirred and mixed, and then 4.33 mL of distilled water was added and stirred evenly. Then, the container was placed in a constant temperature blast drying oven at 120° C. to react for 4 hours to obtain a complex ester;

[0077] Q3: Add 3.2g of complex ester and 3.7g of acrylic acid into a container, mix well, add 10.5mL of double distilled water, and then stir in a 55℃ water bath until all the solids are dissolved. After adding 0.005g of potassium persulfate, place the container in a constant temperature water bath at 80℃ to react for 4h to obtain a reaction mixture, transfer it to a beaker, add 81mL of 95vt% ethanol into the beaker while stirring to precipitate the polymer, collect the solid, wash it 3 times with anhydrous ethanol until the solid becomes a uniform powder, filter it, and dry it at 70℃ for 8h to obtain a pore expander.

[0078] This embodiment provides a method for preparing an imidazole-based dispersant, comprising the following steps:

[0079] S1: 1.41 mL of imidazole and 1.17 mL of 1,2-dibromoethane were added to the container, followed by addition of 50% by volume of sodium hydroxide solution and isopropanol, the mixture was fully stirred, and then the container was placed in a microwave reactor with a power of 400 W, a reaction time of 8 min, and a reaction temperature of 60 ° C. After the reaction was completed, the product was poured into a separatory funnel, allowed to stand for 10 h, and the upper layer of liquid was cooled;

[0080] S2: Add 4.63 mL of 1-bromopentadecane to 1 g of the cooled upper liquid, mix and stir for 20 min, then transfer to a microwave reactor. The microwave reactor power is 500 W, the reaction time is 6 min, and the reaction temperature is 55° C. After the reaction is completed, vacuum distillation is performed at 65° C. and drying is performed at 90° C. for 9 h to obtain a crude imidazole product;

[0081] S3: Dissolve 9.5 g of the crude imidazole product in 22 mL of ethyl acetate, heat in a water bath at 80° C., condense and reflux for 5 min, and purify by recrystallization. Repeat the operation 5 times to obtain an imidazole dispersant.

[0082] This embodiment discloses a pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 29 parts of aluminum sulfate, 58 parts of sodium aluminate, 3.5 parts of pore expander, and 2.5 parts of imidazole-based dispersant.

[0083] This embodiment discloses a method for preparing pseudo-boehmite with strong adsorption performance, comprising the following steps:

[0084] Step (1): adding 150 g / L aluminum sulfate solution, 200 g / L sodium aluminate solution and a pore-enlarging agent into a four-necked flask in a 62° C. constant temperature water bath and equipped with a stirring device through a peristaltic pump, the stirring speed is 90 rpm, the dropping speed of the aluminum sulfate solution is 9 mL / min, and the dropping speed of the sodium aluminate solution is 8 mL / min;

[0085] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and then the pH is adjusted to 10.5, and the solution is aged at 100°C for 5 hours, filtered, washed with deionized water, and dried at 140°C for 14 hours to obtain pseudo-boehmite with strong adsorption properties.

[0086] Example 5

[0087] This embodiment provides a method for preparing a pore expanding agent, comprising the following steps:

[0088] Q1: Dissolve 290g of β-cyclodextrin in 1150mL of distilled water at 85°C, recrystallize at 4°C, discard the upper liquid, dry the obtained crystals at 85°C for 8h, repeat the operation 3 times to obtain high-purity β-cyclodextrin;

[0089] Q2: 5.04 g of high-purity β-cyclodextrin, 2.38 g of maleic acid, 1.04 g of sodium hypophosphite and 0.073 mL of 4-methoxyphenol were added to a container, stirred and mixed, and then 4.58 mL of distilled water was added and stirred evenly. Then, the container was placed in a constant temperature blast drying oven at 120° C. to react for 4 hours to obtain a complex ester;

[0090] Q3: Add 3.7g of complex ester and 3.2g of acrylic acid into a container, mix well, add 11.5mL of double distilled water, and then stir in a 55℃ water bath until all the solids are dissolved. After adding 0.006g of potassium persulfate, place the container in a constant temperature water bath at 80℃ to react for 4h to obtain a reaction mixture, transfer it to a beaker, add 84mL of 95vt% ethanol into the beaker while stirring to precipitate the polymer, collect the solid, wash it 3 times with anhydrous ethanol until the solid becomes a uniform powdery solid, filter it, and dry it at 70℃ for 8h to obtain a pore expander.

[0091] This embodiment provides a method for preparing an imidazole-based dispersant, comprising the following steps:

[0092] S1: 1.58 mL of imidazole and 1.03 mL of 1,2-dibromoethane were added to the container, followed by addition of 50% by volume of sodium hydroxide solution and isopropanol, the mixture was fully stirred, and then the container was placed in a microwave reactor with a power of 400 W, a reaction time of 8 min, and a reaction temperature of 60 ° C. After the reaction was completed, the product was poured into a separatory funnel, allowed to stand for 10 h, and the upper layer of liquid was cooled;

[0093] S2: Add 5.07 mL of 1-bromopentadecane to 1 g of the cooled upper liquid, mix and stir for 20 min, then transfer to a microwave reactor. The microwave reactor power is 500 W, the reaction time is 6 min, and the reaction temperature is 55° C. After the reaction is completed, distill under reduced pressure at 65° C. and dry at 90° C. for 9 h to obtain a crude imidazole product;

[0094] S3: Dissolve 8.5 g of the crude imidazole product in 27 mL of ethyl acetate, heat in a water bath at 80° C., condense and reflux for 5 min, and purify by recrystallization. Repeat the operation 5 times to obtain an imidazole dispersant.

[0095] This embodiment discloses a pseudo-boehmite with strong adsorption performance, which is composed of the following components in parts by weight: 31 parts of aluminum sulfate, 63 parts of sodium aluminate, 4.5 parts of pore expander, and 3.5 parts of imidazole-based dispersant.

[0096] This embodiment discloses a method for preparing pseudo-boehmite with strong adsorption performance, comprising the following steps:

[0097] Step (1): adding 150 g / L aluminum sulfate solution, 200 g / L sodium aluminate solution and a pore-enlarging agent into a four-necked flask in a 62° C. constant temperature water bath and equipped with a stirring device through a peristaltic pump, the stirring speed is 90 rpm, the dropping speed of the aluminum sulfate solution is 9 mL / min, and the dropping speed of the sodium aluminate solution is 8 mL / min;

[0098] Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and then the pH is adjusted to 10.5, and the solution is aged at 100°C for 5 hours, filtered, washed with deionized water, and dried at 140°C for 14 hours to obtain pseudo-boehmite with strong adsorption properties.

[0099] Comparative Example 1

[0100] Comparative Example 1 Compared with Example 1, in the process of preparing the pore expanding agent in Comparative Example 1, no β-cyclodextrin is added, and other conditions remain unchanged.

[0101] Comparative Example 2

[0102] Compared with Example 1, in Comparative Example 2, during the preparation of the pore-enlarging agent, no maleic acid was added, and other conditions remained unchanged.

[0103] Comparative Example 3

[0104] Compared with Example 1, in Comparative Example 3, no acrylic acid is added during the preparation of the pore-enlarging agent, and other conditions remain unchanged.

[0105] Comparative Example 4

[0106] Comparative Example 4 Compared with Example 1, in the process of preparing the imidazole-based dispersant in Comparative Example 4, no imidazole was added, and other conditions remained unchanged.

[0107] Comparative Example 5

[0108] Comparative Example 5 Compared with Example 1, in the process of preparing the imidazole-based dispersant in Comparative Example 5, 1-bromopentadecane was not added, and other conditions remained unchanged.

[0109] Comparative Example 6

[0110] Comparative Example 6 Compared with Example 1, in the process of preparing pseudo-boehmite in Comparative Example 6, no pore expanding agent is added, and other conditions remain unchanged.

[0111] Comparative Example 7

[0112] Comparative Example 7 Compared with Example 1, in the process of preparing pseudo-boehmite in Comparative Example 7, no imidazole-based dispersant was added, and other conditions remained unchanged.

[0113] The pseudo-boehmite prepared in Examples 1-5 and Comparative Examples 1-7 was pressed into sheets and used for XRF testing. The purity of the pseudo-boehmite was detected using a Supermini 200 wavelength dispersive X-ray fluorescence spectrometer. The prepared pseudo-boehmite sample was placed in a glass tube, and the weight of the glass tube and the sample was recorded. Subsequently, degassing was performed at 300° C. for 4 hours to remove moisture and weigh the sample. The glass tube was then placed on a specific surface area and pore analyzer ASAP 2420, and the test program was set. Liquid nitrogen was then added to the Dewar plate, and the program was clicked to run. Adsorption data at different pressures were automatically collected until all the set pressure points were completed. The specific surface area and pore volume of the sample were calculated. The obtained sample was placed in a container, and a series of solutions with different lead ion concentrations were added to the container. The container was placed on a shaker with a rotation speed of 180 rpm for shaking. After shaking for 3 hours, a sample was taken to determine the concentration of the solution, and the maximum adsorption capacity was calculated. The test results are shown in Table 1:

[0114] Table 1

[0115]

[0116]

[0117] It can be seen from the test results in Table 1 that the pseudo-boehmite prepared in Examples 1-5 of the present invention has excellent purity, specific surface area, pore volume and adsorption performance. By comparing Comparative Example 1 with Examples 1-5, it can be seen that the addition of β-cyclodextrin can effectively improve the specific surface area, pore volume and adsorption performance of pseudo-boehmite; by comparing Comparative Example 2 with Examples 1-5, it can be seen that the addition of maleic acid can effectively improve the specific surface area, pore volume and adsorption performance of pseudo-boehmite; by comparing Comparative Example 3 with Examples 1-5, it can be seen that the addition of acrylic acid can effectively improve the specific surface area, pore volume and adsorption performance of pseudo-boehmite; by comparing Comparative Example 4 with Examples 1-5, it can be seen that the addition of imidazole can effectively improve the purity of pseudo-boehmite; by comparing Comparative Example 5 with Examples 1-5, it can be seen that the addition of 1-bromopentadecane can effectively improve the purity of pseudo-boehmite; by comparing Comparative Example 6 with Examples 1-5, it can be seen that the addition of a pore expanding agent can effectively improve the specific surface area, pore volume and adsorption performance of pseudo-boehmite; by comparing Comparative Example 7 with Examples 1-5, it can be seen that the addition of an imidazole-based dispersant can effectively improve the purity of pseudo-boehmite.

[0118] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0119] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing pseudo-boehmite with strong adsorption performance, characterized in that: The invention is composed of the following components in parts by weight: 28-33 parts of aluminum sulfate, 55-68 parts of sodium aluminate, 3-5 parts of a pore expander, and 2-4 parts of an imidazole-based dispersant, wherein the pore expander is obtained by reacting β-cyclodextrin, maleic acid and acrylic acid, and the imidazole-based dispersant is obtained by reacting imidazole, 1,2-dibromoethane and 1-bromopentadecane; The preparation method comprises the following steps: Step (1): adding aluminum sulfate solution, sodium aluminate solution and pore-enlarging agent into a four-necked flask with a constant temperature water bath and a stirring device through a peristaltic pump, and controlling the dropping rate; Step (2): When the amount of aluminum sulfate solution and sodium aluminate solution added is half of the total amount, stop adding, add imidazole-based dispersant, stir, and continue to add the remaining half. After the addition is completed, gel is formed, and the solution is allowed to stand for aging, filtered, washed, and dried to obtain pseudo-boehmite with strong adsorption properties.

2. The preparation method according to claim 1, characterized in that: The preparation method of the pore-enlarging agent comprises the following steps: Q1: Dissolve β-cyclodextrin in distilled water, discard the upper liquid after recrystallization, dry the obtained crystals, and repeat the operation to obtain high-purity β-cyclodextrin; Q2: Add high-purity β-cyclodextrin, maleic acid, sodium hypophosphite and 4-methoxyphenol into a container, stir and mix, add distilled water and stir evenly, then place the container in a constant temperature air drying oven for reaction to obtain a complex ester; Q3: Add the complex ester and acrylic acid into a container, mix well, add double distilled water, and then stir in a water bath until all the solids are dissolved. After adding potassium persulfate, place the container in a constant temperature water bath to react to obtain a reaction mixture, transfer it to a beaker, add ethanol to the beaker while stirring to precipitate a polymer, collect the solid, wash, filter, and dry to obtain a pore expander.

3. The preparation method according to claim 2, characterized in that: In the Q1, the dosage ratio of β-cyclodextrin and distilled water is (250-300) g: (1000-1200) mL, the temperature of the distilled water is 80-85°C, the recrystallization temperature is 3-5°C, the drying temperature is 85-95°C, the time is 6-8h, and the operation is repeated 2-4 times; in the Q2, the molar ratio of high-purity β-cyclodextrin, maleic acid, sodium hypophosphite, 4-methoxyphenol and distilled water is (0.8-1.2): (4-4.4): (2-2.1): (0.1-0.15): (50-55), the reaction temperature is 110-120°C, and the reaction time is 3-4h.

4. The preparation method according to claim 2, characterized in that: In the Q3, the dosage ratio of the complex ester, acrylic acid, double distilled water, potassium persulfate and ethanol is (3-4) g: (3-4) g: (10-12) mL: (0.005-0.006) g: (80-85) mL, the water bath temperature is 50-55°C, the water bath reaction temperature is 70-80°C, the reaction time is 2-4 h, the volume fraction of ethanol is 95vt%, and the solid is washed with anhydrous ethanol for 3-5 times until the solid becomes a uniform powdery solid. The drying temperature is 60-70°C and the reaction time is 6-8 h.

5. The preparation method according to claim 1, characterized in that: The preparation method of the imidazole-based dispersant comprises the following steps: S1: Add imidazole and 1,2-dibromoethane into a container, then add sodium hydroxide solution and isopropanol, stir the mixture thoroughly, and then put the container into a microwave reactor. After the reaction is completed, pour the product into a separatory funnel, let it stand, and take the upper liquid to cool; S2: adding 1-bromopentadecane to the cooled upper liquid, mixing and stirring, and transferring to a microwave reactor. After the reaction is completed, distilling under reduced pressure and drying to obtain a crude imidazole product; S3: Dissolve the crude imidazole product in ethyl acetate, heat in a water bath, condense and reflux, and purify by recrystallization. Repeat the operation to obtain an imidazole dispersant.

6. The preparation method according to claim 5, characterized in that: In S1, the molar ratio of imidazole to 1,2-dibromoethane is (1.8-2.2): (0.9-1.1), the volume fraction of the sodium hydroxide solution is 50vt%, the power of the microwave reactor is 300-500W, the reaction time is 5-9min, the reaction temperature is 55-65°C, and the standing time is 7-10h.

7. The preparation method according to claim 5, characterized in that: In the S2, the molar ratio of the upper liquid to 1-bromopentadecane is 1:(1.9-2.2), the mixing and stirring time is 10-20 min, the microwave reactor power is 400-600 W, the reaction time is 4-8 min, the reaction temperature is 50-60°C, the reduced pressure distillation temperature is 60-65°C, the drying temperature is 80-90°C, and the time is 7-9h.

8. The preparation method according to claim 5, characterized in that: In the S3, the usage ratio of the crude imidazole product and ethyl acetate is (8-10) g: (20-30) mL, the water bath heating temperature is 75-80° C., the condensation reflux time is 3-5 min, and the operation is repeated 3-5 times.

9. The preparation method according to claim 1, characterized in that: In the step (1), the concentration of the aluminum sulfate solution is 150 g / L, the concentration of the sodium aluminate solution is 200 g / L, the water bath temperature is 58-62°C, the stirring speed is 80-100 rpm, the dropping speed of the aluminum sulfate solution is 8-10 mL / min, and the dropping speed of the sodium aluminate solution is 8-10 mL / min; in the step (2), after gelation, the pH is adjusted to 10-11, the static aging temperature is 90-100°C, the time is 3-5 hours, and the solution is washed with deionized water. The drying temperature is 120-140°C and the time is 12-14 hours.

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