A potassium-extracting resin, its preparation method and application

Abstract

The application discloses a potassium-extracting resin, which comprises a chloromethyl polystyrene ball carrier and a polymer layer grafted on the surface of the carrier, wherein the polymer layer has imprinted cavities, the imprinted cavities are formed after template potassium ions are eluted, and the inner wall of the imprinted cavities is distributed with sulfonic acid groups. The potassium-extracting resin has high selectivity to potassium ions.

Description

Technical Field

[0001] This application relates to the field of resin material preparation technology, and in particular to a potassium-extracting resin, its preparation method and application. Background Technology

[0002] Potassium is one of the three essential nutrients for plant growth and is also a mineral resource. my country's potassium salt resources are mainly derived from salt lake brines, which commonly contain complex systems of various alkali metal ions such as potassium, sodium, and lithium. Effective separation of potassium from other alkali metals is a key step in achieving comprehensive utilization of salt lake resources. Ion exchange has become an important method for separating and purifying potassium-containing solutions due to its simplicity and high selectivity. Related studies have shown that strong acid-based sulfonic acid cation exchange resins have a certain adsorption capacity for potassium ions. However, conventional sulfonic acid resins have poor selectivity for alkali metal ions of the same valence, and in aqueous solutions, relying solely on electrostatic interactions is insufficient to achieve efficient separation of potassium from coexisting ions such as sodium and lithium.

[0003] To improve the selectivity of ion exchange materials, ion imprinting technology has emerged. This technology uses target ions as templates, and polymerizes functional monomers with crosslinking agents to form polymers with specific recognition holes. After eluting the template, an adsorbent material with a "memory" effect on the template ion can be obtained. However, in traditional bulk imprinted materials, the recognition sites are deeply embedded inside the polymer, resulting in high mass transfer resistance, long adsorption equilibrium time, and insufficient rigidity. In aqueous phases, they are prone to swelling and loss of selectivity. Summary of the Invention

[0004] The potassium-extraction resin, its preparation method, and its application provided according to one or more embodiments of this application solve one of the technical problems of poor selectivity of traditional sulfonic acid resins for alkali metal ions.

[0005] A first aspect of this application provides a potassium extraction resin, comprising: a chloromethyl polystyrene spherical carrier and a polymer layer grafted onto the surface of the carrier, wherein the polymer layer has imprinted cavities formed after eluting template potassium ions, and the inner walls of the imprinted cavities are distributed with sulfonic acid groups.

[0006] Optionally, the polymer layer is covalently bonded to the carrier surface via thioether bonds; and / or, The polymer layer contains dithiocarbamate groups at the chain ends.

[0007] A second aspect of this application provides a method for preparing potassium-extracting resin, comprising the following steps: Chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface are provided as a carrier; Under an inert atmosphere, the carrier was dispersed in a first solvent, and potassium styrene sulfonate, a crosslinking agent, and a potassium salt were added to the resulting dispersion. Following a photo-initiated free radical polymerization reaction, polymer microspheres encapsulated with potassium ions were obtained; and The polymer microspheres containing potassium ions were acid-eluted and washed with water until neutral, followed by solid-liquid separation to obtain the potassium-extracting resin.

[0008] Optionally, the mass ratio of potassium styrene sulfonate to the carrier is (1~10):10.

[0009] Optionally, the crosslinking agent includes one or more of divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, and / or, The mass ratio of the crosslinking agent to the potassium styrene sulfonate is (1~3):(1~5).

[0010] Optionally, the potassium salt includes one or more of potassium chloride, potassium sulfate, and potassium nitrate; and / or, The mass ratio of the potassium salt to the potassium styrene sulfonate is (1~4):1.

[0011] Optionally, the wavelength of light in the photoinitiated free radical polymerization reaction is 250 nm to 380 nm, and the light intensity in the photoinitiated free radical polymerization reaction is 2 W / cm². 2 ~20W / cm 2 The photo-initiated free radical polymerization reaction is initiated at a temperature of 20°C to 40°C, and the reaction time is 2 hours to 12 hours.

[0012] Optionally, the acid elution uses a 0.5 mol / L to 1 mol / L hydrochloric acid solution; and / or, The acid elution and the water washing are performed alternately at least once until the washing solution is neutral.

[0013] Optionally, the step of providing chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface as a carrier includes: The support was obtained by nucleophilic substitution reaction of chloromethyl polystyrene spheres and diethyl dithiocarbamate in a second solvent.

[0014] Optionally, the mass ratio of the diethyldithiocarbamate to the chloromethyl polystyrene spheres is 1:(2~20); and / or, The mass ratio of the second solvent to the chloromethyl polystyrene spheres is (3~20):1.

[0015] Optionally, the temperature of the nucleophilic substitution reaction is 30℃~90℃, and the time of the nucleophilic substitution reaction is 5h~48h.

[0016] A third aspect of this application provides the application of the potassium-extracting resin as described in the first aspect or the potassium-extracting resin prepared by the preparation method described in the second aspect in potassium ion extraction.

[0017] Compared with the prior art, the technical solution provided in this application has the following beneficial effects: The potassium extraction resin of this application comprises a chloromethyl polystyrene spherical carrier and a polymer layer grafted onto the surface of the carrier. The polymer layer contains imprinted cavities, the inner walls of which are distributed with sulfonic acid groups. These sulfonic acid groups capture cations through Coulomb attraction. Since the imprinted cavities are formed after eluting template potassium ions, their spatial dimensions match the hydrated ionic radius of the potassium ions. When ions in the solution enter the imprinted cavities, only potassium ions with precisely matched hydrated ionic radii can simultaneously contact multiple sulfonic acid groups on the inner wall of the imprinted cavity, forming the most stable "multi-point ionic bond" combination. Smaller sodium ions cannot contact the sulfonic acid groups on either side of the cavity, resulting in extremely weak binding; larger calcium ions cannot even squeeze in, thus creating an ion sieving effect. Therefore, these imprinted cavities can specifically recognize potassium ions, and compared to conventional sulfonic acid resins, the potassium extraction resin of this application exhibits better selectivity for potassium ions. Moreover, unlike traditional bulk imprinted materials where the recognition sites are deeply embedded inside the polymer, the potassium ion recognition sites (imprinted cavities) in the potassium-extracting resin of this application are located in the polymer layer on the surface of the carrier, resulting in a shorter mass transfer path and a faster adsorption rate. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and disclosure, and together with the description serve to explain the principles of this application and disclosure.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the related prior art, the accompanying drawings used in the description of the embodiments or the related prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating a method for preparing potassium-extracting resin according to some embodiments of this application; Figure 2 Electron micrograph of the potassium-extracting resin prepared according to Example 1 of this application; Figure 3 The image shows a scanning electron microscope (SEM) image of the potassium extraction resin prepared according to Example 1 of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0023] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any implementation described in this application can be freely combined with one or more other implementations described in this application, and the resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated in this application, unless those skilled in the art consider the combination to be clearly unreasonable.

[0024] Any method steps, processes, and operations described in this application should not be construed as necessarily requiring them to be performed in a particular order as discussed or shown, unless explicitly specified. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0025] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0026] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0027] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0028] The crosslinking agent is an alkene monomer having at least two polymerizable carbon-carbon double bonds.

[0029] First aspect Some embodiments of this application provide a potassium extraction resin, comprising: a chloromethyl polystyrene spherical carrier and a polymer layer grafted onto the surface of the carrier. The polymer layer has imprinted cavities formed after eluting template potassium ions, and the inner walls of the imprinted cavities are distributed with sulfonic acid groups.

[0030] The potassium extraction resin of this application includes a chloromethyl polystyrene spherical carrier and a polymer layer grafted onto the surface of the carrier. The polymer layer contains imprinted cavities, the inner walls of which are distributed with sulfonic acid groups. These sulfonic acid groups capture cations through Coulomb attraction. Since the imprinted cavities are formed after eluting template potassium ions, their spatial dimensions match the hydrated ionic radius of the potassium ions. When ions in the solution enter the imprinted cavities, only potassium ions with precisely matched hydrated ionic radii can simultaneously contact multiple sulfonic acid groups on the inner wall of the imprinted cavity, forming the most stable "multi-point ionic bond" combination. Sodium ions, with smaller radii, cannot contact the sulfonic acid groups on either side of the cavity, resulting in extremely weak binding; calcium ions, with larger radii, cannot even squeeze in, thus forming an ion sieving effect. Therefore, the imprinted cavities can specifically recognize potassium ions, and compared to conventional sulfonic acid resins, the potassium extraction resin of this application exhibits better selectivity for potassium ions. Moreover, unlike traditional bulk imprinted materials where the recognition sites are deeply embedded inside the polymer, the potassium ion recognition sites (imprinted cavities) in the potassium-extracting resin of this application are located in the polymer layer on the surface of the carrier, resulting in a shorter mass transfer path and a faster adsorption rate.

[0031] Imprinted cavities, as is known in the art, refer to three-dimensional pores left in a polymer network after template ions (or molecules) have been eluted and removed, which are completely complementary to the size, shape, and chemical functional group arrangement of the template ions.

[0032] Imprinted cavities are used for selective adsorption of potassium ions. In some embodiments, the potassium extraction resin has an adsorption capacity of ≥1.5 mmol / g for potassium ions, ≤0.5 mmol / g for sodium ions, ≤0.05 mmol / g for lithium ions, ≤0.3 mmol / g for magnesium ions, and ≤0.1 mmol / g for calcium ions.

[0033] In some implementations, the spatial size of the imprinted cavity is 0.330 nm to 0.335 nm. The spatial size of the imprinted cavity refers to the shortest distance between two sulfonic acid groups on the inner wall of the imprinted cavity.

[0034] It should be noted that the polymer layer grafted onto the carrier surface refers to a polymer layer covalently bonded to the surface of the chloromethyl polystyrene sphere carrier. In some embodiments, the polymer layer is covalently connected to the carrier surface via thioether bonds (-CH2-S-).

[0035] In some embodiments, the polymer layer contains dithiocarbamate groups at the chain ends.

[0036] Second aspect Please see Figure 1 This application provides a method for preparing potassium-extracting resin, comprising the following steps: S1 provides chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface as a carrier; S2, under an inert atmosphere, the support is dispersed in a first solvent, and potassium styrene sulfonate, a crosslinking agent, and a potassium salt are added to the resulting dispersion. Following a photo-initiated free radical polymerization reaction, polymer microspheres encapsulated with potassium ions are obtained; and S3, the polymer microspheres containing potassium ions are acid-eluted and washed with water until neutral, and then separated into solid and liquid components to obtain potassium-extracting resin.

[0037] In some embodiments, the chloromethyl polystyrene spheres have a chlorine content of 15% to 20% and a crosslinking degree of 6% to 8%. These chloromethyl polystyrene spheres can improve the structural stability of potassium-containing resins.

[0038] In some embodiments, the first solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, acetonitrile, and water.

[0039] In some embodiments, the mass ratio of the first solvent to the carrier is (3~20):1. Exemplarily, the mass ratio of the first solvent to the carrier is 20:1, 10:1, 12.5:1, 15:1, 8:1 or 3:1.

[0040] In some embodiments, the mass ratio of potassium styrene sulfonate to the support is (1~10):10. Exemplarily, the mass ratio of potassium styrene sulfonate to the support is 2:10, 4:10, 5:10, 7:10, 8:10, or 1:1. Within this range, the mass ratio of potassium styrene sulfonate to the support can further increase the saturated adsorption capacity of the potassium extraction resin for potassium ions. The higher the proportion of potassium styrene sulfonate, the higher the saturated adsorption capacity of the potassium extraction resin for potassium ions.

[0041] In some embodiments, the crosslinking agent includes one or more of divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate. Preferably, the crosslinking agent includes divinylbenzene, which can enhance the structural stability of the potassium-extracting resin.

[0042] In some embodiments, the mass ratio of the crosslinking agent to potassium styrene sulfonate is (1-3):(1-5). Exemplarily, the mass ratio of the crosslinking agent to potassium styrene sulfonate is 1:1, 3:4, 1:5, 2:2.5, 9:8, or 3:5. Within this range, the mass ratio of the crosslinking agent to potassium styrene sulfonate can further enhance the structural stability of the potassium-extracting resin.

[0043] In some embodiments, the potassium salt includes one or more of potassium chloride, potassium sulfate, and potassium nitrate.

[0044] In some embodiments, the mass ratio of potassium salt to potassium styrene sulfonate is (1-4):1. Exemplarily, the mass ratio of potassium salt to potassium styrene sulfonate is 1:1, 2:1, 9:4, 5:2, 15:7, 3:1, or 4:1. The potassium salt provides potassium ions, which act as a "charge shielding agent," compressing the "ionic atmosphere" thickness around the sulfonate group and reducing chain-to-chain repulsion. This makes it easier and more orderly to graft potassium styrene sulfonate monomers onto the surface of chloromethyl polystyrene spheres, significantly increasing the surface grafting density.

[0045] In some embodiments, the wavelength of light in the photoinitiated free radical polymerization reaction is 250 nm to 380 nm, and the light intensity in the photoinitiated free radical polymerization reaction is 2 W / cm². 2 ~20W / cm 2 The initiation temperature for photo-initiated free radical polymerization is 20℃~40℃, and the reaction time is 2h~12h.

[0046] For example, the wavelength is 250 nm, 254 nm, 365 nm or 380 nm.

[0047] For example, the light intensity is 2 W / cm². 2 5W / cm 2 10W / cm 2 15W / cm 2 17W / cm 2 Or 20W / cm 2 .

[0048] For example, the reaction time in the photoinitiated free radical polymerization reaction is 2h, 5h, 8h, 10h or 12h.

[0049] In some embodiments, the acid elution solution used is a 0.5 mol / L to 1 mol / L hydrochloric acid solution.

[0050] In some embodiments, acid elution and water washing are performed alternately at least once in step S3 until the washing solution is neutral. It should be noted that neutrality refers to a pH value of 6.5 to 7.5. Optionally, acid elution involves mixing and stirring the acid solution with polymer microspheres encapsulated with potassium ions to remove the potassium ions.

[0051] In some embodiments, step S3, which involves acid eluting and washing the potassium-encapsulated polymer microspheres until neutral, includes sequentially performing one acid wash, one water wash, a second acid wash, a second water wash, a third water wash, and a fourth water wash. The final washing solution has a pH of 6.5 to 7.5.

[0052] Optionally, the pickling solution used for a single pickling is a hydrochloric acid solution of 0.5 mol / L to 1.0 mol / L.

[0053] Optionally, the pickling solution used for the secondary pickling is a hydrochloric acid solution of 0.1 mol / L to 0.2 mol / L.

[0054] Optionally, deionized water may be used for the first, second, third, and fourth rinses.

[0055] Optionally, the pickling temperature is 20℃~35℃ and the pickling time is 2h~4h.

[0056] Optionally, the temperature of the secondary pickling is 40℃-50℃, and the time of the secondary pickling is 8h~24h.

[0057] Optionally, the temperature of each wash is 20℃~35℃, and the washing time is 0.5h~2h.

[0058] In some embodiments, the mass ratio of the pickling solution to the polymer microspheres embedded with potassium ions is (3~10):1 during each pickling. For example, the mass ratio of the pickling solution to the polymer microspheres embedded with potassium ions is 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1 during each pickling.

[0059] In some embodiments, step S1 includes: nucleophilic substitution reaction of chloromethyl polystyrene spheres and diethyl dithiocarbamate in a second solvent to obtain a support.

[0060] For example, diethyldithiocarbamate includes sodium diethyldithiocarbamate and / or potassium diethyldithiocarbamate, optionally sodium diethyldithiocarbamate.

[0061] In some alternative embodiments, the mass ratio of diethyldithiocarbamate to chloromethyl polystyrene spheres is 1:(2~20). Exemplarily, the mass ratio of diethyldithiocarbamate to chloromethyl polystyrene spheres is 1:2, 3:10, 1:5, 1:10, 1:12, 1:15, or 1:20. Better grafting densities can be obtained within this range of mass ratios.

[0062] In some alternative embodiments, the second solvent includes one or more of methanol, ethanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, and acetone.

[0063] In some alternative embodiments, the mass ratio of the second solvent to the chloromethyl polystyrene spheres is (3~20):1. Exemplarily, the mass ratio of the second solvent to the chloromethyl polystyrene spheres is 3:1, 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, or 20:1.

[0064] In some alternative embodiments, the nucleophilic substitution reaction is carried out at a temperature of 30°C to 90°C for a duration of 5 h to 48 h.

[0065] For example, the temperature of the nucleophilic substitution reaction is 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or 90°C.

[0066] For example, the nucleophilic substitution reaction can be carried out at times of 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, or 48 h.

[0067] Third aspect Some embodiments of this application provide the application of the potassium-extracting resin described in any embodiment of the first aspect or the potassium-extracting resin prepared by the preparation method described in any embodiment of the second aspect in potassium ion extraction.

[0068] Example To better understand this application, the following description, in conjunction with embodiments, further illustrates this application. However, the scope of protection claimed in this application is not limited to the scope of the embodiments.

[0069] In the following examples, unless otherwise specified, all experimental instruments, raw materials, and quantities involved are commercially available products or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0070] Unless otherwise specified, the specific parameters used in each step of the material preparation process in each embodiment and comparative example are the same.

[0071] Example 1 10 g of chloromethyl polystyrene spheres were dispersed in 100 g of methanol. 0.5 g of sodium diethyldithiocarbamate was added to the resulting dispersion, and the reaction was carried out at 50 °C for 10 h under an argon atmosphere. After the reaction was complete, the reaction solution was filtered, and the solid phase was washed three times alternately with methanol and water to obtain chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface, which were then used as a carrier.

[0072] 10g of the carrier was dispersed in 100g of acetonitrile. 2g of potassium styrenesulfonate, 6g of potassium chloride, and 2g of divinylbenzene were added to the resulting dispersion and mixed. Free radical polymerization was then initiated using a 365nm UV lamp with a light intensity of 5W / cm². 2 The reaction was carried out at 25°C for 6 hours. After the reaction was completed, the reaction solution was subjected to solid-liquid separation to obtain polymer microspheres embedded with potassium ions.

[0073] The polymer microspheres encapsulated with potassium ions were mixed with 15 g of 0.5 mol / L hydrochloric acid solution and stirred and washed for 3 h. The resin after solid-liquid separation was washed with 30 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 30 g of 0.1 mol / L hydrochloric acid solution for 9 h at a washing temperature of 45 °C. The resin after solid-liquid separation was washed with 30 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 30 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 30 g of deionized water for 1 h. After solid-liquid separation, potassium-extracting resin was obtained.

[0074] The electron microscope image of the potassium-extracting resin is as follows: Figure 2 As shown, the scanning electron microscope image is as follows: Figure 3 As shown, its morphology and structure are uniform microspheres.

[0075] Example 2 10g of chloromethyl polystyrene spheres were dispersed in 100g of acetonitrile. 1g of sodium diethyldithiocarbamate was added to the resulting dispersion, and the reaction was carried out at 60℃ for 6 hours under an argon atmosphere. After the reaction was completed, the reaction solution was filtered, and the solid phase was washed three times alternately with methanol and water to obtain chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface, which were then used as a carrier.

[0076] 10g of the carrier was dispersed in 80g of dimethyl sulfoxide. 4g of potassium styrene sulfonate, 9g of potassium chloride, and 3g of divinylbenzene were added to the resulting dispersion and mixed. Free radical polymerization was then initiated using a 254nm UV lamp with a light intensity of 15W / cm². 2 The reaction was carried out at 35°C for 10 hours. After the reaction was completed, the reaction solution was separated into solid and liquid phases to obtain polymer microspheres encapsulated with potassium ions.

[0077] The polymer microspheres encapsulated with potassium ions were mixed with 30 g of 0.8 mol / L hydrochloric acid solution and stirred and washed for 3 h. The resin after solid-liquid separation was washed with 30 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 30 g of 0.2 mol / L hydrochloric acid solution for 9 h at a washing temperature of 42 °C. The resin after solid-liquid separation was washed with 40 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 1 h. After solid-liquid separation, potassium-extracting resin was obtained.

[0078] Example 3 10g of chloromethyl polystyrene spheres were dispersed in 150g of acetone. 5g of sodium diethyldithiocarbamate was added to the resulting dispersion, and the reaction was carried out at 80℃ for 12h under a nitrogen atmosphere. After the reaction was completed, the reaction solution was filtered, and the solid phase was washed three times alternately with methanol and water to obtain chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface, which were then used as a carrier.

[0079] 10g of the carrier was dispersed in 100g of N,N-dimethylformamide. 10g of potassium styrene sulfonate, 20g of potassium chloride, and 8g of divinylbenzene were added to the resulting dispersion and mixed. Free radical polymerization was then initiated using a 365nm UV lamp with a light intensity of 17W / cm². 2 The reaction was carried out at 35°C for 6 hours. After the reaction was completed, the reaction solution was separated into solid and liquid phases to obtain polymer microspheres encapsulated with potassium ions.

[0080] The polymer microspheres encapsulated with potassium ions were mixed with 50 g of 0.7 mol / L hydrochloric acid solution and stirred and washed for 2 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of 0.15 mol / L hydrochloric acid solution for 10 h at a washing temperature of 47 °C. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. After solid-liquid separation, potassium-extracting resin was obtained.

[0081] Example 4 10g of chloromethyl polystyrene spheres were dispersed in 150g of ethanol. 3g of sodium diethyldithiocarbamate was added to the resulting dispersion, and the reaction was carried out at 75°C for 24h under a nitrogen atmosphere. After the reaction was complete, the reaction solution was filtered, and the solid phase was washed three times alternately with methanol and water to obtain chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface, which were then used as a carrier.

[0082] 10g of the carrier was dispersed in 50g of N,N-dimethylformamide and 50g of acetonitrile. 7g of potassium styrenesulfonate, 15g of potassium chloride, and 7g of divinylbenzene were added to the resulting dispersion and mixed. Free radical polymerization was then initiated using a 365nm UV lamp with a light intensity of 17W / cm². 2 The reaction was carried out at 35°C for 6 hours. After the reaction was completed, the reaction solution was subjected to solid-liquid separation to obtain polymer microspheres embedded with potassium ions.

[0083] The polymer microspheres encapsulated with potassium ions were mixed with 50 g of 0.7 mol / L hydrochloric acid solution and stirred and washed for 2 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of 0.15 mol / L hydrochloric acid solution for 10 h at a washing temperature of 47 °C. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. The resin after solid-liquid separation was washed with 40 g of deionized water for 0.5 h. After solid-liquid separation, potassium-extracting resin was obtained.

[0084] Example 5 10 g of chloromethyl polystyrene spheres were dispersed in 60 g of dimethyl sulfoxide. 5 g of sodium diethyldithiocarbamate was added to the resulting dispersion, and the reaction was carried out at 65 °C for 36 h under an argon atmosphere. After the reaction was complete, the reaction solution was filtered, and the solid phase was washed three times alternately with methanol and water to obtain chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface, which were then used as a carrier.

[0085] 10g of the carrier was dispersed in 75g of dimethyl sulfoxide and 50g of water. 8g of potassium styrene sulfonate, 20g of potassium chloride, and 9g of divinylbenzene were added to the resulting dispersion and mixed. Free radical polymerization was then initiated using a 254nm UV lamp with a light intensity of 5W / cm². 2 The reaction was carried out at 27°C for 12 hours. After the reaction was completed, the reaction solution was subjected to solid-liquid separation to obtain polymer microspheres embedded with potassium ions. The polymer microspheres encapsulated with potassium ions were mixed with 70 g of 0.6 mol / L hydrochloric acid solution and stirred and washed for 3 h. The resin after solid-liquid separation was washed with 70 g of deionized water for 1 h. The resin after solid-liquid separation was washed with 70 g of 0.12 mol / L hydrochloric acid solution for 20 h at a washing temperature of 43 °C. The resin after solid-liquid separation was washed with 50 g of deionized water for 2 h. The resin after solid-liquid separation was washed with 50 g of deionized water for 2 h. The resin after solid-liquid separation was washed with 50 g of deionized water for 2 h. After solid-liquid separation, potassium-extracting resin was obtained.

[0086] Comparative Example 1 The method is basically the same as in Example 1, except that the chloromethyl polystyrene spheres are not grafted and modified, and the chloromethyl polystyrene spheres are used directly as the carrier.

[0087] Comparative Example 2 The conventional sulfonic acid resin used is the commercially available macroporous D001 resin, specifically the D001 type from Shandong Zibo Dongda Chemical Co., Ltd. This resin belongs to the macroporous strong acid styrene-based cation exchange resin, with styrene-divinylbenzene copolymer as the backbone and containing sulfonic acid groups (-SO3H). It is obtained by directly sulfonating styrene-divinylbenzene copolymer (white spheres) with concentrated sulfuric acid (introducing -SO3H).

[0088] The potassium-extracting resins prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to the following tests, and the test results are listed in Table 1: 1. Test method for potassium ion saturation adsorption capacity The potassium extraction resins prepared in each example and comparative example were packed into resin columns, with the mass of the potassium extraction resin in the resin column denoted as m. A cation-containing solution (pH 7, K...) was used. + 5000 mg / L, Na + 80000 mg / L, Li + 100 mg / L, Mg 2+ 25000 mg / L, Ca 2+ A potassium ion concentration of 500 mg / L was used as the mother liquor and passed through the resin column in a countercurrent manner at a certain rate. The feeding was stopped when the difference in potassium ion concentration between the effluent and the influent was less than 10 ppm, and the volume V1 of the liquid flowing out of the resin column was measured. The mass difference M1 between the influent and effluent potassium ions was calculated by multiplying V1 by 300 mg / L. The ratio of M1 to the resin column volume m is the saturated adsorption capacity M of the potassium-extracting resin for potassium ions. K + .

[0089] 2. Test method for sodium ion saturation adsorption capacity The potassium-extracting resins prepared in each embodiment and comparative example were packed into resin columns, with the mass of the potassium-extracting resin in the column denoted as m. Using the same cation-containing solution as described above as the adsorption mother liquor, the solution was passed through the resin column in a counter-current manner at a certain speed. The feeding was stopped when the difference in sodium ion concentration between the effluent and the influent was less than 10 ppm, and the volume V2 of the liquid flowing out of the resin column was measured. The mass difference M2 between the influent and effluent sodium ions was calculated by multiplying V2 by 4000 mg / L. The ratio of M2 to the resin column volume m is the saturated adsorption capacity M of the potassium-extracting resin for sodium ions. Na + .

[0090] 3. Test method for lithium-ion saturation adsorption capacity The potassium-extracting resins prepared in each embodiment and comparative example were packed into resin columns, with the mass of the potassium-extracting resin in the column denoted as m. Using the same cation-containing solution as described above as the adsorption mother liquor, the solution was passed through the resin column in a counter-current manner at a certain speed. The feeding was stopped when the difference in lithium ion concentration between the effluent and the influent was less than 10 ppm, and the volume V3 of the liquid flowing out of the resin column was measured. The mass difference M3 between the influent and effluent lithium ions was calculated by multiplying V3 by 25 mg / L. The ratio of M3 to the resin column volume m is the saturated adsorption capacity M of the potassium-extracting resin for sodium ions. Li + .

[0091] 4. Test method for saturated adsorption capacity of magnesium ions The potassium-extracting resins prepared in each embodiment and comparative example were packed into resin columns, with the mass of the potassium-extracting resin in the column denoted as m. Using the same cation-containing solution as described above as the adsorption mother liquor, the solution was passed through the resin column in a counter-current manner at a certain speed. The feeding was stopped when the difference in magnesium ion concentration between the effluent and the influent was less than 10 ppm, and the volume V3 of the liquid flowing out of the resin column was measured. The mass difference M3 between the lithium ions entering and leaving the resin column was calculated by multiplying V3 by 25 mg / L. The ratio of M3 to the resin column volume m is the saturated adsorption capacity M of the potassium-extracting resin for magnesium ions. Mg 2+ .

[0092] 5. Test method for calcium ion saturation adsorption capacity The potassium-extracting resins prepared in each embodiment and comparative example were packed into resin columns, with the mass of the potassium-extracting resin in the column denoted as m. Using the same cation-containing solution as described above as the adsorption mother liquor, the solution was passed through the resin column in a counter-current manner at a certain speed. The feeding was stopped when the difference in calcium ion concentration between the effluent and the influent was less than 10 ppm, and the volume V3 of the liquid flowing out of the resin column was measured. The mass difference M3 between the lithium ions entering and leaving the resin column was calculated by multiplying V3 by 25 mg / L. The ratio of M3 to the resin column volume m is the saturated adsorption capacity M of the potassium-extracting resin for calcium ions. Ca 2+ .

[0093] Table 1

[0094] As can be seen from the data in Table 1, compared with Comparative Examples 1 and 2, the potassium extraction resins prepared in Examples 1-5 have a much higher saturated adsorption capacity for potassium ions than for sodium and lithium ions. This indicates that the potassium extraction resin provided in this application has high selectivity for potassium ions and can specifically identify potassium ions.

[0095] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0096] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0097] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. A potassium-extracting resin, characterized in that, include: The chloromethyl polystyrene sphere carrier and the polymer layer grafted onto the surface of the carrier, wherein the polymer layer has imprinted cavities formed by eluting template potassium ions, and the imprinted cavities have sulfonic acid groups distributed on their inner walls.

2. The potassium-extracting resin according to claim 1, characterized in that, The polymer layer is covalently connected to the carrier surface via thioether bonds; and / or, The polymer layer contains dithiocarbamate groups at the chain ends.

3. A method for preparing the potassium-extracting resin as described in claim 1 or 2, characterized in that, Includes the following steps: Chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface are provided as a carrier; Under an inert atmosphere, the carrier was dispersed in a first solvent, and potassium styrene sulfonate, a crosslinking agent, and a potassium salt were added to the resulting dispersion. Following a photo-initiated free radical polymerization reaction, polymer microspheres encapsulated with potassium ions were obtained; and The polymer microspheres containing potassium ions were acid-eluted and washed with water until neutral, followed by solid-liquid separation to obtain the potassium-extracting resin.

4. The preparation method according to claim 3, characterized in that, The mass ratio of potassium styrene sulfonate to the carrier is (1~10):

10.

5. The preparation method according to claim 3, characterized in that, The crosslinking agent includes one or more of divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, and / or, The mass ratio of the crosslinking agent to the potassium styrene sulfonate is (1~3):(1~5).

6. The preparation method according to claim 3, characterized in that, The potassium salt includes one or more of potassium chloride, potassium sulfate, and potassium nitrate; and / or, The mass ratio of the potassium salt to the potassium styrene sulfonate is (1~4):

1.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The wavelength of light in the photoinitiated free radical polymerization reaction is 250 nm to 380 nm, and the light intensity in the photoinitiated free radical polymerization reaction is 2 W / cm². 2 ~20W / cm 2 The photo-initiated free radical polymerization reaction is initiated at a temperature of 20°C to 40°C, and the reaction time is 2 hours to 12 hours.

8. The preparation method according to claim 3, characterized in that, The acid elution uses a 0.5 mol / L to 1 mol / L hydrochloric acid solution; and / or, The acid elution and the water washing are performed alternately at least once until the washing solution is neutral.

9. The preparation method according to claim 1, characterized in that, The step of providing chloromethyl polystyrene spheres with dithiocarbamate groups grafted onto their surface as a carrier includes: The support was obtained by nucleophilic substitution reaction of chloromethyl polystyrene spheres and diethyl dithiocarbamate in a second solvent.

10. The preparation method according to claim 1, characterized in that, The mass ratio of the diethyldithiocarbamate to the chloromethyl polystyrene spheres is 1:(2~20); and / or, The mass ratio of the second solvent to the chloromethyl polystyrene spheres is (3~20):

1.

11. The preparation method according to claim 7 or 8, characterized in that, The nucleophilic substitution reaction is carried out at a temperature of 30℃ to 90℃ and for a duration of 5h to 48h.

12. The application of the potassium-extracting resin as described in claim 1 or 2, or the potassium-extracting resin prepared by the preparation method according to any one of claims 3 to 11, in potassium ion extraction.

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