A method for preparing a high-selectivity lithium ion adsorbent
By grafting polyethylene glycol ether chains and sulfonic acid groups onto lithium-ion adsorbents, the problem of low selectivity of lithium-ion adsorbents in magnesium-rich wastewater in existing technologies is solved, achieving efficient adsorption of lithium ions and improving adsorption capacity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGYIN SUQING NEW MATERIAL CO LTD
- Filing Date
- 2025-09-28
- Publication Date
- 2026-06-23
AI Technical Summary
Existing lithium-ion adsorbents have low selectivity in lithium-containing wastewater rich in magnesium ions, making it difficult to effectively adsorb lithium ions and easily interfered with by magnesium ions.
The monomers such as methyl p-styrene sulfonate, p-chloromethylstyrene, and divinylbenzene are copolymerized to form an organic cross-linking network, which is then grafted with polyethylene glycol ether chains and sulfonic acid groups. This improves lithium ion selectivity and reduces magnesium ion adsorption through steric hindrance and electrostatic attraction.
It achieves efficient adsorption of lithium ions under magnesium ion-rich conditions, improves adsorption capacity and adsorption rate, and enhances the cycle stability of lithium ion adsorbent.
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Figure BDA0005619034180000101 
Figure BDA0005619034180000111
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmentally friendly functional materials technology, and in particular relates to a method for preparing a highly selective lithium-ion adsorbent. Background Technology
[0002] With the rapid development of electric vehicles, energy storage systems, and consumer electronics, lithium-ion batteries have become the mainstream energy storage technology, leading to a continuous increase in lithium battery production. This has directly driven the expansion of lithium resource mining and processing, resulting in a significant increase in lithium-containing wastewater. When lithium-containing wastewater is directly discharged into the environment, lithium ions may inhibit the activity of beneficial microorganisms, alter the microbial community structure in aquatic bodies, affect the decomposition of organic matter and nutrient cycling, and, in the long term, may disrupt the stability of local aquatic ecosystems. Therefore, lithium-containing wastewater needs to be treated to remove lithium ions before discharge. Ion exchange technology is an important method for treating lithium-containing wastewater. However, conventional lithium-ion adsorbents containing sulfonic acid and carboxylic acid groups have poor selectivity. When treating wastewater containing both lithium ions and high concentrations of magnesium ions, these adsorbents often preferentially adsorb the higher-charge magnesium ions, making it difficult to effectively adsorb lithium ions.
[0003] Chinese patent document CN116920807B discloses a lithium-ion adsorbent for lithium extraction from salt lakes and its preparation method, including the following steps: Styrene, N'N-methylenebisacrylamide, octanol, and ethylbenzene are mixed uniformly; benzoyl peroxide and azobisisobutyronitrile are added; the mixture is stirred at room temperature until completely homogeneous; a precursor powder composed of aluminum sulfate powder and urea powder is added; after heating and reaction, macroporous resin is obtained; the macroporous resin is crushed, washed, and sieved to obtain resin particles; the resin particles are added to a lithium chloride solution; the temperature is controlled at 90℃; the reaction is carried out for 6 hours; the mixture is cooled; the resin is filtered out; and then activated in a sodium chloride solution to obtain the lithium-ion adsorbent. This method utilizes the ammonia and hydroxyl groups generated by the slow hydrolysis of urea during heating to convert aluminum ions into aluminum hydroxide gel in situ. Through lithium-ion intercalation and sodium chloride displacement elution processes, ion sieve channels with sizes matching lithium ions are constructed, achieving selective recognition of lithium ions.
[0004] The lithium-ion adsorbent prepared by the aforementioned patent contains aluminum hydroxide gel. The hydroxyl groups on the surface of the aluminum hydroxide gel are deprotonated to form negatively charged centers located inside the pores. These negatively charged centers combine with lithium ions through non-specific electrostatic adsorption. In lithium-containing wastewater rich in magnesium ions, magnesium ions, due to their double charge, have a stronger binding ability with the negatively charged centers and are more readily adsorbed than lithium ions. At the same time, magnesium ions, due to their large hydration radius and slow diffusion, tend to accumulate at the pore openings and form electrostatic shields, hindering the inward diffusion of lithium ions and reducing the effective adsorption sites. Therefore, the lithium-ion adsorbent prepared by the aforementioned patent has low selectivity for lithium ions in lithium-containing wastewater rich in magnesium ions. Summary of the Invention
[0005] This invention provides a method for preparing a highly selective lithium-ion adsorbent, which suppresses the interference of magnesium ions and achieves efficient adsorption of lithium ions in lithium-containing wastewater rich in magnesium ions.
[0006] To solve the above problems, the present invention adopts the following technical solution:
[0007] A method for preparing a highly selective lithium-ion adsorbent includes the following steps:
[0008] S1. Methyl p-styrene sulfonate, p-chloromethylstyrene, divinylbenzene, toluene, n-heptane, and an initiator are mixed to obtain an oil phase mixture. The oil phase mixture is added to an aqueous phase mixture, stirred and emulsified, heated and reacted, washed, and then reacted with sodium hydroxide solution. After washing, copolymer microspheres are obtained. The aqueous phase mixture is prepared by dissolving polyvinyl alcohol in deionized water.
[0009] S2. The copolymer microspheres were dispersed in anhydrous ethanol, diethyl phosphite and DBU (1,8-diazabicyclo) were added, the mixture was heated and reacted, washed, reacted with hydrochloric acid solution, washed, dispersed in ethanol solution, ammonia was added in a closed environment, the mixture was heated and reacted, and washed to obtain the modified copolymer microspheres.
[0010] S3. The modified copolymer microspheres were dispersed in anhydrous ethanol, and polyethylene glycol monoglycidyl ether was added under an inert atmosphere. The mixture was heated to react, washed, and dried to obtain a lithium ion adsorbent.
[0011] The oil phase mixture was emulsified into droplets by adding it to the aqueous phase mixture. After heating, the carbon-carbon double bonds of methyl styrene sulfonate, p-chloromethylstyrene, and divinylbenzene underwent a copolymerization reaction under the initiation of an initiator, forming an organic cross-linked network. Subsequently, the mixture was treated with sodium hydroxide solution, and the ester groups of methyl styrene sulfonate were hydrolyzed to form sodium sulfonate, yielding copolymer microspheres. Under the catalysis of DBU, a portion of the chloromethyl groups on the copolymer microspheres reacted with diethyl phosphite to form phosphate diester groups, which were then hydrolyzed with hydrochloric acid solution to form phosphonic acid groups. Another portion of the chloromethyl groups on the copolymer microspheres reacted with ammonia to form primary amino groups, yielding modified copolymer microspheres. The primary amino groups on the modified copolymer microspheres underwent a ring-opening reaction with the epoxy groups of polyethylene glycol monoglycidyl ether, grafting polyethylene glycol ether chains onto the modified copolymer microspheres, resulting in lithium ion adsorption structures with an organic cross-linked network as the backbone and chemically bonded sulfonic acid groups, phosphonic acid groups, and polyethylene glycol ether chains. In lithium-ion adsorbents treating lithium-containing wastewater rich in magnesium ions, polyethylene glycol ether chains utilize their hydrophilic properties to form a hydration layer barrier on the surface of the adsorbent. This barrier effectively repels magnesium ions with large hydration radii and high hydration energies through steric hindrance. Lithium ions with smaller size and lower dehydration energy can cross the hydration layer barrier through local dehydration, achieving initial selection of lithium ions and preventing phosphonic acid and sulfonic acid groups from binding extensively with magnesium ions, thus increasing the adsorption capacity of the lithium-ion adsorbent. Sulfonic acid groups have a strong electrostatic attraction to lithium ions, reducing the mass transfer resistance of lithium ions, increasing the mass transfer rate of lithium ions, and accelerating the adsorption speed of the lithium-ion adsorbent. When lithium ions diffuse into the hydrophobic microenvironment constructed by the organic cross-linked network, they are dehydrated. The dehydrated lithium ions are more likely to form stable coordination with phosphonic acid groups than magnesium ions, further improving the selectivity of the lithium-ion adsorbent for lithium ions.
[0012] Methyl styrene sulfonate is used as a monomer to participate in the construction of the organic cross-linking network. The methyl sulfonate group has weak hydrophilicity and can be uniformly distributed in the oil phase mixture during the emulsification stage and participate uniformly in the copolymerization reaction. This is conducive to the formation of a uniform organic cross-linking network with high mechanical strength. It can effectively disperse the internal stress generated during the adsorption and desorption cycle and improve the cycle stability of the lithium ion adsorbent. In addition, the ester group of methyl styrene sulfonate is hydrolyzed to generate sulfonic acid groups that are widely distributed in the lithium ion adsorbent, preventing magnesium ions from accumulating on the surface of the lithium ion adsorbent and blocking the lithium ion mass transfer channels.
[0013] Furthermore, the oil phase mixture also contains tetradecylstyrene.
[0014] Tetradecylstyrene has a hydrophobic long alkyl chain, which introduces more hydrophobic microregions into the organic cross-linking network. These hydrophobic microregions can reduce local water activity, promote the dehydration of lithium ions with low dehydration energy barriers, and at the same time repel magnesium ions with extremely high dehydration energy barriers. The dehydrated lithium ions are more likely to form stable coordination with the oxygen atoms of phosphonic acid groups, improve the binding efficiency of lithium ions with phosphonic acid groups, and increase the selectivity of lithium ion adsorbents for lithium ions.
[0015] Furthermore, in step S1, after adding the oil phase mixture to the aqueous phase mixture, the mixture is stirred and emulsified at 500 rpm for 1 hour, heated to 75°C, and stirred at 300 rpm for 6 hours. The mixture is then washed sequentially with anhydrous ethanol, cyclohexane, and anhydrous ethanol. The mixture is then added to a sodium hydroxide solution, stirred at 300 rpm for 1 hour, and washed with deionized water and anhydrous ethanol to obtain copolymer microspheres.
[0016] Organic impurities such as toluene, n-heptane, and unreacted divinylbenzene monomers, which are encapsulated in the cross-linked network of organic matter, are removed by anhydrous ethanol and cyclohexane to obtain a lithium-ion adsorbent with open, interconnected channels. This reduces the mass transfer resistance of lithium ions diffusing inside the adsorbent and improves the adsorption rate.
[0017] Furthermore, the concentration of the sodium hydroxide solution is 7 wt%.
[0018] Further, in step S2, the copolymer microspheres are added to anhydrous ethanol and stirred at 800 rpm for 10 min. Diethyl phosphite and DBU are added, the temperature is raised to 70°C, and the mixture is stirred at 300 rpm for 6 h. After washing with deionized water, the mixture is added to hydrochloric acid solution and stirred at 800 rpm for 10 min. The temperature is raised to 80°C, and the mixture is stirred at 300 rpm for 6 h. After washing with deionized water, the mixture is added to ethanol solution and stirred at 800 rpm for 15 min. Ammonia water is added in a sealed environment, the temperature is raised to 60°C, and the mixture is stirred at 300 rpm for 12 h. After washing with deionized water and anhydrous ethanol, the modified copolymer microspheres are obtained.
[0019] Furthermore, the concentration of the ammonia solution is 28-30 wt%.
[0020] First, a portion of the chloromethyl groups on the copolymer microspheres are converted into phosphonic acid groups using diethyl phosphite, DBU, and hydrochloric acid solution. Then, under conditions of excess high-concentration ammonia, closed high-pressure environment, and suitable temperature, another portion of the chloromethyl groups on the copolymer microspheres is converted into primary amino groups with high efficiency and selectivity. This avoids strong acid treatment in the presence of primary amino groups and ensures that the modified copolymer microspheres have a high density of primary amino groups.
[0021] Furthermore, in step S3, the modified copolymer microspheres are added to anhydrous ethanol and stirred at 800 rpm for 10 min. Under nitrogen protection, polyethylene glycol monoglycidyl ether is added, the temperature is raised to 70°C, and the mixture is stirred at 300 rpm for 8 h. After filtration, the mixture is washed with anhydrous ethanol and deionized water and dried under reduced pressure to obtain the lithium ion adsorbent.
[0022] Furthermore, the molar mass of the polyethylene glycol monoglycidyl ether is 550 g / mol.
[0023] The polyethylene glycol ether chain generated by the reaction of 550 g / mol polyethylene glycol monoglycidyl ether with a primary amino group can form a sufficiently thick and stable hydration layer on the surface of the lithium ion adsorbent, providing effective steric hindrance and efficiently repelling magnesium ions.
[0024] Furthermore, vacuum drying was carried out at 10.1 kPa and 60°C for 10 hours.
[0025] Drying under reduced pressure at 60°C is a suitable temperature to prevent the polyethylene glycol ether chains from breaking and to protect the integrity and hydrophilicity of the polyethylene glycol ether chains.
[0026] Furthermore, the lithium-ion adsorbent comprises the following raw materials in parts by weight: 160.2-243.6 parts of oil phase mixture, 418-510 parts of aqueous phase mixture, 8-15 parts of diethyl phosphite, 9-16 parts of DBU, 10-16 parts of ammonia, and 6-12 parts of polyethylene glycol monoglycidyl ether. The oil phase mixture comprises the following raw materials in parts by weight: 45-65 parts of methyl p-styrene sulfonate, 30-45 parts of p-chloromethylstyrene, 5-8 parts of tetradecylstyrene, 15-25 parts of divinylbenzene, 30-50 parts of toluene, 35-50 parts of n-heptane, and 0.2-0.6 parts of initiator. The initiator is azobisisobutyronitrile. The aqueous phase mixture is prepared by dissolving 8-10 parts of polyvinyl alcohol in 410-500 parts of deionized water.
[0027] The beneficial effects of this invention are:
[0028] By grafting polyethylene glycol ether chains onto a lithium-ion adsorbent, a hydration layer barrier is formed on the adsorbent surface. This barrier utilizes its steric hindrance effect to repel magnesium ions while allowing lithium ions to pass through, achieving initial selection of lithium ions and reducing the influence of magnesium ions on the adsorption capacity of the lithium-ion adsorbent. The lithium-ion adsorbent also contains sulfonic acid and phosphonic acid groups. The sulfonic acid groups have a strong electrostatic attraction effect, which improves the mass transfer rate of lithium ions. When lithium ions diffuse into the hydrophobic microenvironment constructed by the organic cross-linked network, they are dehydrated. The dehydrated lithium ions are more likely to form stable coordination with the phosphonic acid groups than magnesium ions, thus achieving adsorption and improving the selectivity of lithium ions. The polyethylene glycol ether chains, sulfonic acid groups, and phosphonic acid groups work synergistically to improve the adsorption capacity, adsorption rate, and selectivity of the lithium-ion adsorbent.
[0029] When an oil-phase mixture containing methyl styrene sulfonate is emulsified and dispersed in an aqueous phase mixture, the methyl sulfonate groups, being weakly hydrophilic, will not aggregate at the oil-water interface, which is beneficial for obtaining a uniform lithium-ion adsorbent with high mechanical strength and strong cycle stability. At the same time, the sulfonic acid groups generated by the hydrolysis of the methyl sulfonate groups are widely distributed in the lithium-ion adsorbent, preventing a large amount of magnesium ions from being adsorbed on the surface of the lithium-ion adsorbent and thus blocking the mass transfer channels. Detailed Implementation
[0030] Example 1
[0031] Dissolve 8g of polyvinyl alcohol-1799 in 410g of deionized water to obtain an aqueous phase mixture. Mix 45g of methyl p-styrene sulfonate, 30g of p-chloromethylstyrene, 5g of tetradecylstyrene, 15g of divinylbenzene, 30g of toluene, 35g of n-heptane, and 0.2g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture, stir at 500rpm for 1h, heat to 75℃ at a rate of 10℃ / h, stir at 300rpm for 6h, filter, wash 3 times with anhydrous ethanol, wash 3 times with cyclohexane, wash once with anhydrous ethanol, add 400g of 7wt% sodium hydroxide solution, stir at 300rpm for 1h, filter, wash 4 times with deionized water, and wash twice with anhydrous ethanol to obtain copolymer microspheres.
[0032] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 10g of diethyl phosphite and 12g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 12g of 30wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and then washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0033] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 8g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0034] Example 2
[0035] Dissolve 10g of polyvinyl alcohol-1799 in 420g of deionized water to obtain an aqueous phase mixture. Mix 50g of methyl p-styrene sulfonate, 38g of p-chloromethylstyrene, 6g of tetradecylstyrene, 20g of divinylbenzene, 37g of toluene, 40g of n-heptane, and 0.3g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres.
[0036] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 9g of diethyl phosphite and 9g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 14g of 28wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0037] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 9g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0038] Example 3
[0039] Dissolve 8g of polyvinyl alcohol-1799 in 450g of deionized water to obtain an aqueous phase mixture. Mix 55g of methyl p-styrene sulfonate, 30g of p-chloromethylstyrene, 7g of tetradecylstyrene, 25g of divinylbenzene, 35g of toluene, 38g of n-heptane, and 0.5g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres.
[0040] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 8g of diethyl phosphite and 10g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 10g of 30wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0041] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 10g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0042] Example 4
[0043] Dissolve 9g of polyvinyl alcohol-1799 in 470g of deionized water to obtain an aqueous phase mixture. Mix 65g of methyl p-styrene sulfonate, 42g of p-chloromethylstyrene, 6g of tetradecylstyrene, 17g of divinylbenzene, 45g of toluene, 45g of n-heptane, and 0.2g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres.
[0044] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 12g of diethyl phosphite and 16g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 16g of 29wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0045] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 6g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0046] Example 5
[0047] Dissolve 10g of polyvinyl alcohol-1799 in 500g of deionized water to obtain an aqueous phase mixture. Mix 65g of methyl p-styrene sulfonate, 45g of p-chloromethylstyrene, 8g of tetradecylstyrene, 25g of divinylbenzene, 50g of toluene, 50g of n-heptane, and 0.6g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres.
[0048] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 15g of diethyl phosphite and 12g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 15g of 30wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and then washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0049] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 12g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0050] Example 6
[0051] Dissolve 10g of polyvinyl alcohol-1799 in 500g of deionized water to obtain an aqueous phase mixture. Mix 65g of methyl p-styrene sulfonate, 45g of p-chloromethylstyrene, 25g of divinylbenzene, 50g of toluene, 50g of n-heptane, and 0.6g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres.
[0052] The copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Then, 15g of diethyl phosphite and 12g of DBU were added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed twice with deionized water, and then added to 300g of 15wt% hydrochloric acid solution. The mixture was stirred at 800rpm for 10min, the temperature was raised to 80℃, and the mixture was stirred at 300rpm for 6h. The mixture was filtered, washed three times with deionized water, and then added to 500g of 75wt% ethanol solution. The mixture was stirred at 800rpm for 15min, transferred to a high-pressure reactor, and 15g of 30wt% ammonia solution was added. The temperature was raised to 60℃, and the mixture was stirred at 300rpm for 12h. The mixture was filtered, washed three times with deionized water, and then washed three times with anhydrous ethanol to obtain the modified copolymer microspheres.
[0053] The modified copolymer microspheres were added to 300g of anhydrous ethanol and stirred at 800rpm for 10min. Under nitrogen protection, 12g of 550g / mol polyethylene glycol monoglycidyl ether was added, the temperature was raised to 70℃, and the mixture was stirred at 300rpm for 8h. The mixture was filtered, washed three times with anhydrous ethanol, and three times with deionized water. It was then dried in an environment of 10.1kPa and 60℃ for 10h to obtain the lithium ion adsorbent.
[0054] The present invention also includes comparative examples and related experiments.
[0055] Comparative Example 1
[0056] The difference between this comparative example and Example 5 is that the modified copolymer microspheres were not treated with polyethylene glycol monoglycidyl ether, while the remaining operation steps and reaction conditions were the same as in Example 5, resulting in a lithium ion adsorbent.
[0057] Comparative Example 2
[0058] The difference between this comparative example and Example 5 is that methyl p-styrene sulfonate is replaced with p-styrene sulfonic acid, while the remaining operating steps and reaction conditions are the same as in Example 5, to obtain a lithium ion adsorbent.
[0059] Comparative Example 3
[0060] The difference between this comparative example and Example 5 is that the copolymerized microspheres were not treated with sodium hydroxide solution; the remaining operation steps and reaction conditions were the same as in Example 5, resulting in a lithium-ion adsorbent.
[0061] Comparative Example 4
[0062] Dissolve 8g of polyvinyl alcohol-1799 in 410g of deionized water to obtain an aqueous phase mixture. Mix 60g of methyl p-styrene sulfonate, 45g of p-chloromethylstyrene, 5g of tetradecylstyrene, 23g of divinylbenzene, 45g of toluene, 50g of n-heptane, and 0.6g of azobisisobutyronitrile to obtain an oil phase mixture. Add the oil phase mixture to the aqueous phase mixture and stir at 500rpm for 1h. Increase the temperature to 75℃ at a rate of 10℃ / h and stir at 300rpm for 6h. Filter, wash 3 times with anhydrous ethanol, 3 times with cyclohexane, and 1 time with anhydrous ethanol. Add 400g of 7wt% sodium hydroxide solution and stir at 300rpm for 1h. Filter, wash 4 times with deionized water, and 2 times with anhydrous ethanol to obtain copolymer microspheres. Add the copolymer microspheres to 300g of anhydrous ethanol and stir at 800rpm for 10min. Under nitrogen protection, add 12g of... 550 g / mol polyethylene glycol monoglycidyl ether was heated to 70 °C, stirred at 300 rpm for 8 h, filtered, washed 3 times with anhydrous ethanol and 3 times with deionized water, and dried in an environment of 10.1 kPa and 60 °C for 10 h to obtain lithium ion adsorbent.
[0063] Comparative Example 5
[0064] A lithium-ion adsorbent was prepared according to the method described in Chinese patent document CN116920807B.
[0065] Lithium-ion adsorbent adsorption rate, adsorption capacity and cycle performance test
[0066] Lithium chloride and magnesium chloride were added to deionized water to obtain a salt solution for simulating lithium-containing wastewater. The lithium ion concentration in the salt solution was 229.2 mg / L, and the magnesium ion concentration was 15.3 g / L. 5 g of each lithium ion adsorbent prepared in each example and comparative example was added to 850 g of 2 wt% hydrochloric acid solution and soaked for 4 hours. The solution was then removed and washed with deionized water until the pH of the eluent was 6.5-7. The following adsorption-regeneration cycle was then performed: the solution was packed into an ion exchange column, and the salt solution was pumped into the ion exchange column at a rate of 70 g / min using a peristaltic pump. The lithium ion concentration in the effluent from the ion exchange column was monitored in real time. The breakthrough point was defined as a lithium ion concentration of 11.4-11.5 mg / L, and the corresponding time was recorded as the breakthrough time (min). The saturation point was defined as a lithium ion concentration of 217.7-217.8 mg / L, and the corresponding time was recorded as the saturation time (min). After adsorption, the lithium ion adsorbent was removed, and 850 g of... The adsorption-regeneration process was carried out by soaking in 2wt% hydrochloric acid solution for 4 hours. The solution was washed with deionized water until the pH of the wash solution was 6.5-7, completing one adsorption-regeneration cycle. The above cycle was repeated, and the breakthrough time (min) and saturation time (min) after the 1st, 5th, 10th and 30th cycles were recorded, as shown in Table 1.
[0067] Table 1
[0068]
[0069]
[0070] As can be seen from Table 1, the breakthrough time and saturation time of Examples 1 to 5 are longer than those of Example 6, indicating that the introduction of tetradecylstyrene into the lithium-ion adsorbent can accelerate the adsorption rate of lithium ions and increase the adsorption capacity of lithium ions. After 30 cycles, the breakthrough time and saturation time of Example 5 are both longer than those of the comparative examples, indicating that the lithium-ion adsorbent constructed by simultaneously introducing phosphonic acid groups, polyethylene glycol ether chains, and sulfonic acid groups widely distributed thereon onto the organic crosslinking framework has excellent performance in terms of good cycle stability, fast adsorption rate, and large adsorption capacity.
Claims
1. A method for preparing a highly selective lithium-ion adsorbent, characterized in that, Includes the following steps: S1. Methyl p-styrene sulfonate, p-chloromethylstyrene, divinylbenzene, toluene, n-heptane, and initiator are mixed to obtain an oil phase mixture. The oil phase mixture is added to an aqueous phase mixture, stirred and emulsified, heated and reacted, washed, and then reacted with sodium hydroxide solution. After washing, copolymer microspheres are obtained. The aqueous mixture was prepared by dissolving polyvinyl alcohol in deionized water; S2. The copolymer microspheres were dispersed in anhydrous ethanol, diethyl phosphite and DBU were added, the mixture was heated and reacted, washed, reacted with hydrochloric acid solution, washed, dispersed in ethanol solution, ammonia was added in a closed environment, the mixture was heated and reacted, and washed to obtain modified copolymer microspheres. S3. The modified copolymer microspheres were dispersed in anhydrous ethanol, and under an inert atmosphere, 550 g / mol of polyethylene glycol monoglycidyl ether was added. The mixture was heated to react, washed, and dried to obtain a lithium ion adsorbent. The lithium-ion adsorbent comprises the following raw materials in parts by weight: 160.2-243.6 parts of oil phase mixture, 418-510 parts of aqueous phase mixture, 8-15 parts of diethyl phosphite, 9-16 parts of DBU, 10-16 parts of ammonia, and 6-12 parts of polyethylene glycol monoglycidyl ether; the oil phase mixture comprises the following raw materials in parts by weight: 45-65 parts of methyl p-styrene sulfonate, 30-45 parts of p-chloromethylstyrene, 5-8 parts of tetradecylstyrene, 15-25 parts of divinylbenzene, 30-50 parts of toluene, 35-50 parts of n-heptane, and 0.2-0.6 parts of initiator; the initiator is azobisisobutyronitrile; the aqueous phase mixture is prepared by dissolving 8-10 parts of polyvinyl alcohol in 410-500 parts of deionized water.
2. The method for preparing a highly selective lithium-ion adsorbent according to claim 1, wherein the oil phase mixture further contains tetradecylstyrene.
3. The method for preparing a highly selective lithium-ion adsorbent according to claim 2, characterized in that, In step S1, after adding the oil phase mixture to the aqueous phase mixture, the mixture is stirred and emulsified at 500 rpm for 1 hour, heated to 75°C, and stirred at 300 rpm for 6 hours. The mixture is then washed sequentially with anhydrous ethanol, cyclohexane, and anhydrous ethanol. The mixture is then added to a sodium hydroxide solution, stirred at 300 rpm for 1 hour, and washed with deionized water and anhydrous ethanol to obtain copolymer microspheres.
4. The method for preparing a highly selective lithium-ion adsorbent according to claim 3, characterized in that, The concentration of the sodium hydroxide solution is 7 wt%.
5. The method for preparing a highly selective lithium-ion adsorbent according to claim 4, characterized in that, In step S2, the copolymer microspheres are added to anhydrous ethanol and stirred at 800 rpm for 10 min. Diethyl phosphite and DBU are added, the temperature is raised to 70°C, and the mixture is stirred at 300 rpm for 6 h. After washing with deionized water, the mixture is added to hydrochloric acid solution and stirred at 800 rpm for 10 min. The temperature is raised to 80°C, and the mixture is stirred at 300 rpm for 6 h. After washing with deionized water, the mixture is added to ethanol solution and stirred at 800 rpm for 15 min. Ammonia water is added in a sealed environment, the temperature is raised to 60°C, and the mixture is stirred at 300 rpm for 12 h. After washing with deionized water and anhydrous ethanol, the modified copolymer microspheres are obtained.
6. The method for preparing a highly selective lithium-ion adsorbent according to claim 5, characterized in that, The concentration of the ammonia water is 28-30 wt%.
7. The method for preparing a highly selective lithium-ion adsorbent according to claim 6, characterized in that, In step S3, the modified copolymer microspheres are added to anhydrous ethanol and stirred at 800 rpm for 10 min. Under nitrogen protection, polyethylene glycol monoglycidyl ether is added, the temperature is raised to 70°C, and the mixture is stirred at 300 rpm for 8 h. After filtration, the mixture is washed with anhydrous ethanol and deionized water and dried under reduced pressure to obtain the lithium ion adsorbent.
8. The method for preparing a highly selective lithium-ion adsorbent according to claim 7, characterized in that, The material was dried under reduced pressure at 10.1 kPa and 60°C for 10 hours.