A method for preparing carbon nanotube-supported aluminum adsorbents by water suspension

Abstract

This invention belongs to the field of adsorbent preparation technology and discloses a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension. The method includes the following steps: mixing a lithium source, an aluminum source, water, and liquid alkali; heat-curing, drying, and grinding to obtain aluminum adsorbent powder; mixing the aluminum adsorbent powder with carbon nanotubes to obtain aluminum adsorbent precursor powder; mixing water, an emulsifier, and a dispersant to obtain an aqueous phase; mixing an organic solvent, a polymer material, and the aluminum adsorbent precursor powder to obtain an oil phase; adding the oil phase dropwise to the aqueous phase to form a dispersion system; heating the dispersion system to remove the organic solvent, obtaining granular aluminum adsorbent. The carbon nanotube-supported aluminum adsorbent prepared by water suspension has small and uniform particles, strong hydrophilicity, large specific surface area, strong structural stability, high mechanical strength, good impact resistance, and can efficiently and selectively adsorb lithium ions in brine with high adsorption capacity, low adsorption loss, and long cycle life.

Description

Technical Field

[0001] This invention relates to the field of adsorbent preparation technology, and in particular to a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension. Background Technology

[0002] Research on aluminum-based adsorbents began in the 1970s, with Dow Chemical in the United States being the first to successfully prepare them. After several generations of improvements, they have become relatively mature adsorbents with industrial applications. In practical applications, Livent (FMC Lithium), Lanke Lithium, and Zangge Lithium have successively achieved industrialization. The theoretical adsorption capacity of aluminum-based adsorbents in powder form is approximately 20 mg / g, the saturated adsorption capacity after granulation is approximately 3–5 mg / g, and the dynamic adsorption capacity in practice is approximately 1–3 mg / g. They are suitable for chloride or magnesium sulfate subtype salt lakes with pH values ​​of 5–7.

[0003] The adsorption capacity of aluminum-based adsorbents varies considerably depending on the brine composition and the performance of the adsorbent. While powdered aluminum-based adsorbents offer advantages such as large solid-liquid contact area, fast lithium ion adsorption rate, and large adsorption capacity, large-scale adsorption experiments can lead to problems such as high column pressure and powder loss due to the small gaps in the filter column caused by the powder buildup.

[0004] Due to the numerous problems associated with powdered aluminum-based adsorbents, researchers have increasingly focused on granulation techniques. One such method, water suspension granulation, is widely used in the preparation of resin material frameworks and in explosive molding. While water suspension produces uniform and small-sized particles, the molded particles suffer from poor structural properties and low hydrophilicity. Therefore, addressing these issues with water suspension granulation has become a crucial research direction in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, which solves the problems of large particle size and poor hydrophilicity of adsorbent particles in the traditional kneading and granulation preparation of adsorbent particles.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, comprising the following steps:

[0008] (1) Mix lithium source, aluminum source, water and liquid alkali, stir to react, keep warm to solidify, dry, grind to obtain aluminum adsorbent powder;

[0009] (2) Mix aluminum-based adsorbent powder with carbon nanotubes to obtain aluminum-based adsorbent precursor powder;

[0010] (3) Water, emulsifier and dispersant are mixed to obtain an aqueous phase; organic solvent, polymer material and aluminum-based adsorbent precursor powder are mixed to obtain an oil phase;

[0011] (4) The oil phase is added dropwise to the aqueous phase to form a dispersion system. Then the dispersion system is heated to remove the organic solvent and obtain particulate aluminum adsorbent.

[0012] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the lithium source in step (1) is lithium chloride, lithium sulfate, lithium hydroxide or lithium carbonate, and the aluminum source in step (1) is aluminum chloride or aluminum sulfate.

[0013] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the molar ratio of lithium in the lithium source to aluminum in the aluminum source in step (1) is 1:2 to 5.

[0014] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the mixing method of lithium source, aluminum source, water and liquid alkali in step (1) is as follows: the mixed solution of lithium source, aluminum source and water is added dropwise to liquid alkali, the final pH value of the drop is 5 to 8, and the drop rate is 5 to 20 mL / min.

[0015] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the temperature of heat preservation and curing in step (1) is 50-80°C, the time of heat preservation and curing in step (1) is 1-2 hours, and the temperature of drying in step (1) is 40-60°C.

[0016] Preferably, in the method for preparing aluminum-based adsorbents supported on carbon nanotubes by water suspension, the carbon nanotubes in step (2) include one or more of hydroxyl-modified multi-walled carbon nanotubes, aldehyde-modified multi-walled carbon nanotubes, carboxyl-modified multi-walled carbon nanotubes, carbonyl-modified multi-walled carbon nanotubes, hydroxyl-modified single-walled carbon nanotubes, aldehyde-modified single-walled carbon nanotubes, carboxyl-modified single-walled carbon nanotubes, and carbonyl-modified single-walled carbon nanotubes, and the mass of the carbon nanotubes in step (2) is 0.5% to 2% of the aluminum-based adsorbent powder.

[0017] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, the equipment for mixing the aluminum adsorbent powder with carbon nanotubes in step (2) is a plow mixer, ball mill, fusion machine or high-speed centrifuge.

[0018] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the emulsifier in step (3) is alkylphenol polyoxyethylene ether, N-dodecyl dimethylamine or sodium alkylbenzene sulfonate; the dispersant in step (3) is tricalcium phosphate, sodium pyrophosphate, sodium tripolyphosphate or sodium metaphosphate; and the volume-to-mass ratio of water, emulsifier and dispersant in step (3) is 500 mL: 0.5-2 g: 0.5-2 g.

[0019] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, the organic solvent in step (3) is dimethylacetamide, N-methylpyrrolidone, dichloromethane, or chloroform; the polymer material in step (3) is polystyrene, polysulfone, polyimide, or polyvinylidene fluoride; and the volume-to-mass ratio of the organic solvent, polymer material, and aluminum adsorbent precursor powder in step (3) is 200 mL: 5–10 g: 30–50 g.

[0020] Preferably, in the method for preparing carbon nanotube-supported aluminum adsorbent by water suspension, the endpoint of the heating of the dispersion system in step (4) is 40-200°C, and the heating rate of the dispersion system is 1-3°C / min.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention utilizes carbon nanotube-supported aluminum granular adsorbent prepared by water suspension. The particles are small, have a large specific surface area, strong hydrophilicity, good structural performance, good particle uniformity, stable structure, high mechanical strength, and good impact resistance. Furthermore, the carbon nanotube-supported aluminum adsorbent particles can efficiently and selectively adsorb lithium ions in brine, thereby increasing the fluidity and filtration rate of brine, fast adsorption / desorption rate, high adsorption capacity, low adsorption loss, and long cycle life.

[0023] (2) The present invention adopts a high-strength organic framework and adds hydrophilic carbon nanotubes with high structural performance, which effectively solves the problem of poor structural performance and hydrophilicity of water suspension granulation particles and improves the adsorption capacity of aluminum adsorbent granules. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0025] Figure 1 The apparent morphology of the carbon nanotube-supported aluminum adsorbent particles prepared in Example 1. Detailed Implementation

[0026] This invention provides a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, comprising the following steps:

[0027] (1) Mix lithium source, aluminum source, water and liquid alkali, stir to react, keep warm to solidify, dry, grind to obtain aluminum adsorbent powder;

[0028] (2) Mix aluminum-based adsorbent powder with carbon nanotubes to obtain aluminum-based adsorbent precursor powder;

[0029] (3) Water, emulsifier and dispersant are mixed to obtain an aqueous phase; organic solvent, polymer material and aluminum-based adsorbent precursor powder are mixed to obtain an oil phase;

[0030] (4) The oil phase is added dropwise to the aqueous phase to form a dispersion system; then the dispersion system is heated to remove the organic solvent and obtain particulate aluminum adsorbent.

[0031] In this invention, the lithium source in step (1) is preferably lithium chloride, lithium sulfate, lithium hydroxide or lithium carbonate, more preferably lithium chloride or lithium carbonate, and even more preferably lithium chloride.

[0032] In this invention, the aluminum source in step (1) is preferably aluminum chloride or aluminum sulfate, and more preferably aluminum chloride.

[0033] In this invention, the mass concentration of the liquid alkali in step (1) is preferably 20-32%, more preferably 24-28%, and even more preferably 25%.

[0034] In this invention, the molar ratio of lithium in the lithium source to aluminum in the aluminum source in step (1) is preferably 1:2 to 5, more preferably 1:3 to 4, and even more preferably 1:3.

[0035] In this invention, the preferred method for mixing the lithium source, aluminum source, water and liquid alkali in step (1) is as follows: the mixed solution of lithium source, aluminum source and water is added dropwise to the liquid alkali; the endpoint of the addition is preferably pH = 5-8, more preferably 6-7, and even more preferably 7; the flow rate of the addition is preferably 5-20 mL / min, more preferably 8-15 mL / min, and even more preferably 10 mL / min; the concentration of the aluminum source in the mixed solution of lithium source, aluminum source and water is preferably 0.5-2 mol / L, more preferably 0.8-1.5 mol / L, and even more preferably 1 mol / L.

[0036] In this invention, the temperature of heat preservation and curing in step (1) is preferably 40-80°C, more preferably 50-60°C, and even more preferably 60°C; the time of heat preservation and curing is preferably 1-2 hours, more preferably 1.5-2 hours, and even more preferably 2 hours.

[0037] In this invention, the drying temperature in step (1) is preferably 40–60°C, more preferably 50–60°C, and even more preferably 50°C. This invention does not limit the grinding method; any method well-known to those skilled in the art can be used.

[0038] In this invention, the grinding process in step (1) preferably includes sieving; the mesh size of the sieve used for sieving is preferably ≥100 mesh.

[0039] In this invention, the carbon nanotubes in step (2) preferably include one or more of the following: hydroxyl-modified multi-walled carbon nanotubes, aldehyde-modified multi-walled carbon nanotubes, carboxyl-modified multi-walled carbon nanotubes, carbonyl-modified multi-walled carbon nanotubes, hydroxyl-modified single-walled carbon nanotubes, aldehyde-modified single-walled carbon nanotubes, carboxyl-modified single-walled carbon nanotubes, and carbonyl-modified single-walled carbon nanotubes. More preferably, they include one or more of the following: hydroxyl-modified multi-walled carbon nanotubes, carboxyl-modified multi-walled carbon nanotubes, hydroxyl-modified single-walled carbon nanotubes, and carboxyl-modified single-walled carbon nanotubes. Most preferably, they are hydroxyl-modified multi-walled carbon nanotubes. After modification, hydroxyl-modified carbon nanotubes exhibit the best hydrophilicity. Adding hydroxyl-modified carbon nanotubes to the molded particles can improve the hydrophilicity of the particles and increase the ion exchange rate of the adsorbent.

[0040] In this invention, the mass of the carbon nanotubes in step (2) is preferably 0.5-2% of the aluminum-based adsorbent powder, more preferably 1-1.5%, and even more preferably 1.2%.

[0041] In this invention, the equipment for mixing the aluminum adsorbent powder and carbon nanotubes in step (2) is preferably a plow mixer, ball mill, fusion machine or high-speed centrifuge, more preferably a ball mill or high-speed centrifuge, and even more preferably a ball mill.

[0042] In this invention, the emulsifier in step (3) is preferably alkylphenol polyoxyethylene ether, N-dodecyl dimethylamine or sodium alkylbenzene sulfonate, more preferably alkylphenol polyoxyethylene ether or sodium alkylbenzene sulfonate, and even more preferably sodium alkylbenzene sulfonate.

[0043] In this invention, the dispersant in step (3) is preferably tricalcium phosphate, sodium pyrophosphate, sodium tripolyphosphate or sodium metaphosphate, more preferably tricalcium phosphate, sodium pyrophosphate or sodium metaphosphate, and more preferably sodium metaphosphate.

[0044] In this invention, the volume-to-mass ratio of water, emulsifier and dispersant in step (3) is preferably 500mL:0.5-2g:0.5-2g, more preferably 500mL:0.5-1g:0.5-1g, and even more preferably 500mL:1g:1g.

[0045] In this invention, the mixing speed of water, emulsifier and dispersant in step (3) is preferably 200-400 rpm, more preferably 250-350 rpm, and even more preferably 350 rpm; the mixing time is preferably 1-3 h, more preferably 1.5-2.5 h, and even more preferably 2 h.

[0046] In this invention, the organic solvent in step (3) is preferably dimethylacetamide, N-methylpyrrolidone, dichloromethane or trichloromethane, more preferably N-methylpyrrolidone, dichloromethane or trichloromethane, and more preferably dichloromethane.

[0047] In this invention, the polymer material in step (3) is preferably polystyrene, polysulfone, polyimide or polyvinylidene fluoride, more preferably polystyrene, polyimide or polyvinylidene fluoride, and even more preferably polystyrene.

[0048] In this invention, the volume-to-mass ratio of the organic solvent, polymer material, and aluminum-based adsorbent precursor powder in step (3) is preferably 200mL:5-10g:30-50g, more preferably 200mL:8-10g:40-50g, and even more preferably 200mL:10g:50g. Excessive carbon nanotubes will reduce the proportion of adsorbent and decrease the adsorption capacity of the adsorbent particles; however, insufficient carbon nanotubes will reduce the structural properties and hydrophilicity of the adsorbent particles, further resulting in poor structural properties and reduced adsorption capacity.

[0049] In this invention, the mixing speed of the organic solvent, polymer material and aluminum-based adsorbent precursor powder in step (3) is preferably 200-400 rpm, more preferably 250-350 rpm, and even more preferably 300 rpm; the mixing time is preferably 1-4 h, more preferably 2-3 h, and even more preferably 3 h.

[0050] In this invention, the volume ratio of the oil phase to the water phase in step (4) is preferably 1:3 to 5, more preferably 1:3 to 4, and even more preferably 1:3.

[0051] In this invention, the rotation speed at which the oil phase is added to the aqueous phase in step (4) is preferably 200-400 rpm, more preferably 250-350 rpm, and even more preferably 300 rpm; the rate at which the oil phase is added to the aqueous phase is preferably 5-20 mL / min, more preferably 10-15 mL / min, and even more preferably 10 mL / min.

[0052] In this invention, the endpoint of the heating of the dispersion system in step (4) is preferably 40-200°C, more preferably 60-150°C, and even more preferably 60°C; the heating rate of the dispersion system is preferably 1-3°C / min, more preferably 2-3°C / min, and even more preferably 3°C / min.

[0053] In this invention, step (4) after removing the organic solvent preferably further includes: sequentially washing, drying, and sieving; the washing agent is preferably water; the drying temperature is preferably 50-80°C, more preferably 65-80°C, and even more preferably 80°C.

[0054] In this invention, the particle size of the granular aluminum adsorbent in step (4) is preferably 0.1 to 1 mm, more preferably 0.2 to 0.5 mm, and even more preferably 0.2 mm.

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0056] Example 1

[0057] This embodiment provides a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, including the following steps:

[0058] (1) Anhydrous lithium chloride and anhydrous aluminum chloride were dissolved in deionized water to prepare a mixed solution, wherein the molar ratio of lithium to aluminum was 1:2 and the concentration of aluminum source in the mixed solution was 1 mol / L; the above mixed solution was added dropwise to 32% sodium hydroxide at a flow rate of 20 mL / min using a peristaltic pump. The dropwise addition was stopped when the pH reached 6, and the solution was kept at 60℃ for 2 h to solidify; then the solution was filtered, washed, dried at 50℃, ground, and passed through a 200-mesh sieve to obtain aluminum-based adsorbent powder;

[0059] (2) 0.5g of hydroxyl-modified multi-walled carbon nanotubes and 50g of aluminum-based adsorbent powder were mixed in a ball mill at 300rpm for 2h to obtain aluminum-based adsorbent precursor powder.

[0060] (3) Add 500 mL of ultrapure water, 1 g of dodecylphenol polyoxyethylene ether and 1 g of tricalcium phosphate to a three-necked flask in sequence, and stir and mix at 300 rpm for 1 h to obtain an aqueous phase;

[0061] Add 200 mL of dichloromethane, 10 g of polystyrene (molecular weight 35000), and 50 g of aluminum-based adsorbent precursor powder to a beaker, and stir and mix at 300 rpm for 1 h to obtain the oil phase;

[0062] (4) The oil phase is added dropwise to the aqueous phase at a rate of 10 mL / min. Under the action of tricalcium phosphate and alkylphenol polyoxyethylene ether, the organic solvent can be suspended and dispersed in the aqueous phase to form a stable dispersion system. Then, a water bath is used to heat the water, and the heating rate is precisely controlled at 1℃ / min. The temperature is gradually increased to 60℃, so that the dichloromethane organic solvent is slowly distilled out from the aqueous phase. The volume of the distilled dichloromethane organic solvent is observed. At the same time, a sample is taken from the three-necked bottle to observe the hardness of the particles to determine the degree of solidification. When the organic solvent is completely distilled and collected, the solid product is washed with deionized water, dried at 80℃, and sieved to obtain aluminum adsorbent granules with a particle size of 0.1 mm.

[0063] Example 2

[0064] This embodiment provides a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, including the following steps:

[0065] (1) Anhydrous lithium chloride and anhydrous aluminum chloride were dissolved in deionized water to prepare a mixed solution, wherein the molar ratio of lithium to aluminum was 1:2 and the concentration of aluminum source in the mixed solution was 0.5 mol / L; the above mixed solution was added dropwise to 30% sodium hydroxide at a flow rate of 20 mL / min using a peristaltic pump. The dropwise addition was stopped when the pH reached 6, and the solution was kept at 60℃ for 2 hours to solidify; then the solution was filtered, washed, dried at 50℃, ground, and passed through a 200-mesh sieve to obtain aluminum-based adsorbent powder;

[0066] (2) 1g of hydroxyl-modified single-walled carbon nanotubes and 50g of aluminum-based adsorbent powder were mixed at 400rpm for 2h to obtain aluminum-based adsorbent precursor powder.

[0067] (3) Add 500 mL of ultrapure water, 0.5 g of sodium octadecylbenzenesulfonate and 0.5 g of sodium pyrophosphate to a three-necked flask in sequence, and stir at 300 rpm for 2 h to obtain an aqueous phase;

[0068] Add 200 mL of N-methylpyrrolidone, 5 g of polyimide (molecular weight 80000), and 50 g of aluminum-based adsorbent precursor powder to a beaker, and stir and mix at 300 rpm for 1 h to obtain the oil phase;

[0069] (4) The oil phase is added dropwise to the aqueous phase at a rate of 20 mL / min. Under the action of sodium pyrophosphate and sodium alkylbenzene sulfonate, the organic solvent can be suspended and dispersed in the aqueous phase to form a stable dispersion system. Then, a water bath is used to heat the water, and the heating rate is precisely controlled at 1℃ / min. The temperature is gradually increased to 60℃, so that the N-methylpyrrolidone organic solvent is slowly distilled out from the aqueous phase. The volume of the distilled N-methylpyrrolidone organic solvent is observed. At the same time, a sample is taken from the three-necked flask to observe the hardness of the particles to determine the degree of solidification. When the organic solvent is completely distilled and collected, the solid product is washed with deionized water, dried at 80℃, and sieved to obtain aluminum adsorbent granules with a particle size of 0.2 mm.

[0070] Example 3

[0071] This embodiment provides a method for preparing carbon nanotube-supported aluminum adsorbents by water suspension, including the following steps:

[0072] (1) Anhydrous lithium chloride and anhydrous aluminum chloride were dissolved in deionized water to prepare a mixed solution, wherein the molar ratio of lithium to aluminum was 1:2 and the concentration of aluminum source in the mixed solution was 2 mol / L; the above mixed solution was added dropwise to 30% sodium hydroxide at a flow rate of 20 mL / min using a peristaltic pump. The dropwise addition was stopped when the pH reached 6, and the solution was kept at 60℃ for 2 hours to solidify; then the solution was filtered, washed, dried at 50℃, ground, and passed through a 200-mesh sieve to obtain aluminum-based adsorbent powder;

[0073] (2) 1g of carbonyl-modified single-walled carbon nanotubes and 50g of aluminum-based adsorbent powder were mixed at 400rpm for 2h to obtain aluminum-based adsorbent precursor powder.

[0074] (3) Add 500 mL of ultrapure water, 1 g of sodium dodecylbenzenesulfonate and 1 g of sodium metaphosphate to a three-necked flask in sequence, and stir at 300 rpm for 2 h to obtain an aqueous phase;

[0075] Add 200 mL of chloroform, 10 g of polystyrene (molecular weight 35000), and 50 g of aluminum-based adsorbent precursor powder to a beaker, and stir and mix at 300 rpm for 2 h to obtain the oil phase;

[0076] (4) The oil phase is added dropwise to the aqueous phase at a rate of 20 mL / min. Under the action of sodium metaphosphate and sodium alkylbenzene sulfonate, the organic solvent can be suspended and dispersed in the aqueous phase to form a stable dispersion system. Then, a water bath is used to heat the water, and the heating rate is precisely controlled at 1℃ / min. The temperature is gradually increased to 60℃, so that the trichloromethane organic solvent is slowly distilled out from the aqueous phase. The volume of the distilled trichloromethane organic solvent is observed. At the same time, a sample is taken from the three-necked bottle to observe the hardness of the particles to determine the degree of solidification. When the organic solvent is completely distilled and collected, the solid product is washed with deionized water, dried at 80℃, and sieved to obtain aluminum-based adsorbent granules with a particle size of 0.1 mm.

[0077] Comparative Example 1

[0078] This comparative example provides a method for preparing aluminum-based adsorbents by adhesive extrusion granulation, including the following steps:

[0079] The aluminum-based adsorbent powder prepared in step (1) of Example 1 was granulated by a binder screw extrusion method. 50g of aluminum-based adsorbent powder, 10g of binder PVC (molecular weight of 80000) and 100mL of organic solvent DMF were bonded and extruded in a twin screw extruder at 10MPa to prepare columnar adsorbent particles with a length of 1-0.5cm and a diameter of 1cm.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing aluminum-based adsorbents by adhesive extrusion granulation. The difference between this method and Comparative Example 1 is that the aluminum-based adsorbent powder prepared in step (1) of Example 1 is replaced with the aluminum-based adsorbent powder prepared in step (1) of Example 2. Other parameters and conditions are the same as those in Comparative Example 1.

[0082] Comparative Example 3

[0083] This comparative example provides a method for preparing aluminum-based adsorbents by adhesive extrusion granulation. The difference between this method and Comparative Example 1 is that the aluminum-based adsorbent powder prepared in step (1) of Example 1 is replaced with the aluminum-based adsorbent powder prepared in step (1) of Example 3. Other parameters and conditions are the same as those in Comparative Example 1.

[0084] Adsorption experiments were conducted on the aluminum-based adsorbent granules of Examples 1-3 and the columnar adsorbent granules obtained in Comparative Examples 1-3. Argentine salt lake brine with a Li content of 0.4 mg / L was used. 5 g of adsorbent was added to 200 mL of brine. After adsorption for 12 h, the adsorption capacity data of the above adsorbents are shown in Table 1.

[0085] Table 1. Comparison of adsorption capacity data for several adsorbents

[0086]

[0087] As can be seen from Table 1, the adsorbents prepared by water suspension granulation in Examples 1-3 have higher adsorption capacities than those prepared by traditional extrusion granulation. Furthermore, because this invention uses water suspension to prepare adsorbent particles, it solves the problem that "in industrial adsorption columns, the high column pressure of the adsorbent powder and the poor fluidity of the brine prevent the powder adsorbent from being used in industrial applications."

[0088] Table 2 shows the mass loss results of the aluminum-based adsorbent granules of Examples 1-3 and the columnar adsorbent granules obtained in Comparative Examples 1-3 after 100 cycles of adsorption, which resulted in pulverization.

[0089] Table 2. Mass loss results of several adsorbents after 100 cycles of adsorption and pulverization

[0090]

[0091] As can be seen from Table 2, the adsorbent prepared by the water suspension granulation method of the present invention has a smaller degree of pulverization of particles and higher mechanical strength of structure during long-term cyclic adsorption.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing carbon nanotube-supported aluminum-based adsorbents by water suspension, characterized in that, Includes the following steps: (1) Mix lithium source, aluminum source, water and liquid alkali, stir to react, keep warm to solidify, dry, grind to obtain aluminum adsorbent powder; (2) Mix aluminum-based adsorbent powder with carbon nanotubes to obtain aluminum-based adsorbent precursor powder; (3) Water, emulsifier and dispersant are mixed to obtain an aqueous phase; organic solvent, polymer material and aluminum-based adsorbent precursor powder are mixed to obtain an oil phase; (4) The oil phase is added dropwise to the aqueous phase to form a dispersion system. Then the dispersion system is heated to remove the organic solvent and obtain particulate aluminum adsorbent. In step (1), the molar ratio of lithium in the lithium source to aluminum in the aluminum source is 1:2~5; The temperature for heat preservation and curing in step (1) is 50~80℃, and the time for heat preservation and curing in step (1) is 1~2h; The mass of the carbon nanotubes in step (2) is 0.5-2% of the aluminum-based adsorbent powder; The polymer material mentioned in step (3) is polystyrene, polysulfone, polyimide, or polyvinylidene fluoride; The volume ratio of the oil phase to the water phase in step (4) is 1:3~5; In step (4), the rate at which the oil phase is added to the aqueous phase is 5~20 mL / min.

2. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The lithium source in step (1) is lithium chloride, lithium sulfate, lithium hydroxide or lithium carbonate, and the aluminum source in step (1) is aluminum chloride or aluminum sulfate.

3. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The specific method of mixing lithium source, aluminum source, water and liquid alkali in step (1) is as follows: the mixed solution of lithium source, aluminum source and water is added dropwise to liquid alkali, the final pH value of the drop is 5~8, and the drop rate is 5~20mL / min.

4. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The drying temperature in step (1) is 40~60℃.

5. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The carbon nanotubes in step (2) include one or more of the following: hydroxyl-modified multi-walled carbon nanotubes, aldehyde-modified multi-walled carbon nanotubes, carboxyl-modified multi-walled carbon nanotubes, carbonyl-modified multi-walled carbon nanotubes, hydroxyl-modified single-walled carbon nanotubes, aldehyde-modified single-walled carbon nanotubes, carboxyl-modified single-walled carbon nanotubes, and carbonyl-modified single-walled carbon nanotubes.

6. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The equipment used to mix the aluminum-based adsorbent powder and carbon nanotubes in step (2) is a plow mixer, ball mill, fusion machine or high-speed centrifuge.

7. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The emulsifier in step (3) is alkylphenol polyoxyethylene ether, N-dodecyl dimethylamine or sodium alkylbenzene sulfonate; the dispersant in step (3) is tricalcium phosphate, sodium pyrophosphate, sodium tripolyphosphate or sodium metaphosphate; the volume-to-mass ratio of water, emulsifier and dispersant in step (3) is 500mL:0.5~2g:0.5~2g.

8. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The organic solvent in step (3) is dimethylacetamide, N-methylpyrrolidone, dichloromethane or chloroform; the volume-to-mass ratio of the organic solvent, polymer material and aluminum-based adsorbent precursor powder in step (3) is 200mL: 5~10g: 30~50g.

9. The method for preparing carbon nanotube-supported aluminum adsorbents by water suspension as described in claim 1, characterized in that, The endpoint of the heating of the dispersion system in step (4) is 40~200℃, and the heating rate of the dispersion system is 1~3℃ / min.

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