Pyrones-based chelating resins, methods for their preparation and methods for impurity removal

Abstract

The application relates to a pyrone-based chelating resin, a preparation method thereof and a method for removing impurities. The main chain skeleton of the pyrone-based chelating resin is a styrene-based adsorption resin, and at least one pyrone functional group is branched on the side chain. The multi-oxygen structure of the pyrone functional group and the nitrogen atom on the main chain skeleton can produce strong coordination with aluminum ions, and a stable six-membered ring chelate is formed through a chelation reaction, thereby showing excellent selective aluminum removal performance. Meanwhile, the pyrone functional group has acid-base properties, can undergo ion exchange reaction or physical adsorption with organic matters, and thus can effectively remove TOC in a water environment. Therefore, by using the pyrone-based chelating resin provided in the application, the aluminum ions and TOC in a rare earth solution can be efficiently removed through the synergistic cooperation of the multi-oxygen coordination effect and the selective ion exchange capacity, and the loss rate of the rare earth ions is obviously reduced.

Description

Technical Field

[0001] This application relates to the field of rare earth product technology, and in particular to a pyranone-based chelating resin and its preparation and purification methods. Background Technology

[0002] Rare earth elements (REEs), often referred to as industrial gold, possess unique optical, magnetic, and catalytic properties, playing a crucial role in fields such as displays, hybrid vehicles, superconductors, and nuclear energy applications. The value of rare earth products is typically influenced by their purity, thus requiring impurity removal treatment of the rare earth feedstock during the preparation process.

[0003] Rare earth feed solutions refer to solutions or suspensions containing rare earth elements. These solutions typically contain impurities such as aluminum and total organic carbon (TOC), which affect the purity and performance of rare earth products. However, traditional methods for removing aluminum and TOC from rare earth feed solutions suffer from high rare earth loss rates and low impurity removal rates. Summary of the Invention

[0004] Therefore, it is necessary to provide a pyranone-based chelating resin and its preparation method and impurity removal method to solve the problems of high rare earth loss rate and low impurity removal rate when traditional methods remove aluminum and TOC from rare earth solutions.

[0005] The above-mentioned objective of this application is achieved through the following technical solution:

[0006] In a first aspect, this application provides a pyranone-based chelating resin. The pyranone-based chelating resin has a structure as shown in general formula (I):

[0007] (I); (Ⅱ-1); (Ⅱ-2);

[0008] Where n is selected from positive integers;

[0009] R1 and R2 are each independently selected from H, the structure shown in general formula (II-1), and the structure shown in general formula (II-2), and R1 and R2 are not simultaneously selected from H;

[0010] Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

[0011] In some embodiments, R3 and R4 each appear independently selected from one of H, hydroxyl, carboxyl, C1-C3 alkyl, hydroxyl-substituted C1-C3 alkyl, and C1-C3 alkoxy.

[0012] In some embodiments, R3 and R4 are each independently selected from one of H, hydroxyl, carboxyl, methyl, hydroxymethyl and methoxy groups each time they appear.

[0013] In some embodiments, the pyranone-based chelating resin has an adsorption capacity for TOC ≥1800 mg / g.

[0014] In some embodiments, the pyranone-based chelating resin has an adsorption capacity for aluminum ions ≥20 mg / g.

[0015] In some embodiments, the adsorption capacity of the pyranone-based chelating resin for rare earth ions is ≤0.02 mg / g.

[0016] A second aspect of this application provides a method for preparing a pyranone-based chelating resin, comprising the following steps:

[0017] The amino resin, pyranone compound, and aldehyde compound are subjected to a Mannich reaction to obtain the pyranone-based chelating resin.

[0018] The amino resin has a structure as shown in general formula (Ⅳ), the pyranone compound has a structure as shown in general formula (Ⅴ-1) or general formula (Ⅴ-2), and the aldehyde compound includes formaldehyde or paraformaldehyde;

[0019] (Ⅳ); (V-1); (V-1);

[0020] Where n is a positive integer;

[0021] Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or substituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

[0022] In some embodiments, the pyranone compound includes at least one of 5-hydroxy-2-hydroxymethyl-4-pyranone, 3-hydroxy-2-methyl-4-pyranone, 5-methoxy-2-hydroxymethyl-4-pyranone, 4-methoxy-6-methyl-2-pyranone, and 2-pyranone-5-carboxylic acid.

[0023] In some embodiments, an amino resin, a pyranone compound, and an aldehyde compound are subjected to a Mannich reaction, comprising the following steps: mixing the amino resin, the pyranone compound, the aldehyde compound, and a third solvent, heating to 60°C to 100°C, adding a catalyst, and refluxing for 6 to 12 hours to obtain the pyranone-based chelating resin.

[0024] In some embodiments, the mass ratio of the amino resin, the pyranone compound, and the aldehyde compound is 1:(1~3):(0.15~0.45).

[0025] In some embodiments, the mass ratio of the amino resin, the catalyst, and the third solvent is 1:(0.1~0.3):(4~6).

[0026] In some embodiments, the catalyst comprises at least one of an inorganic acid and an inorganic base.

[0027] In some embodiments, the third solvent includes a proton solvent.

[0028] In some embodiments, the preparation method of the amino resin includes the Gabriel synthesis method.

[0029] A third aspect of this application provides a method for removing impurities from a rare earth liquid, comprising the following steps:

[0030] The rare earth solution is adsorbed using the above-mentioned pyranone-based chelating resin, or the pyranone-based chelating resin prepared by the above-mentioned method, to remove aluminum ions and TOC from the rare earth solution.

[0031] In some embodiments, the method for removing impurities from the rare earth slurry includes the following steps:

[0032] The pyranone-based chelating resin was packed into a chromatography column and pretreated with water to obtain a blank column.

[0033] The rare earth material solution is passed through the blank column for adsorption treatment to obtain an adsorption solution and an adsorption column.

[0034] The adsorption column is desorbed using an acid solution to obtain an desorption solution and a desorption column;

[0035] The desorption column is regenerated using water to obtain the blank column.

[0036] In some embodiments, the aspect ratio of the chromatography column is 8 to 20.

[0037] In some embodiments, during the adsorption treatment, the amount of rare earth feed solution used is 1.5 BV to 9 BV, and the flow rate of the rare earth feed solution is 1 BV / h to 5 BV / h.

[0038] In some embodiments, during the desorption process, the amount of acid used is 2 BV to 6 BV, and the flow rate of the acid is 1 BV / h to 5 BV / h.

[0039] In some embodiments, the mass fraction of the acid in the acid solution is 5% to 15%.

[0040] In some embodiments, the acid in the acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0041] In some embodiments, in the pretreatment and / or the regeneration treatment, the amount of water used is 2 BV to 5 BV, and the water flow rate is 1 BV / h to 5 BV / h.

[0042] This application has at least the following beneficial effects:

[0043] The pyranone-based chelating resin provided in this application has a styrene-based adsorption resin backbone with at least one pyranone functional group branched onto its side links. The multi-oxygen structure of the pyranone functional group and the nitrogen atom on the backbone can strongly coordinate with aluminum ions, forming a stable six-membered ring chelate through a chelation reaction. This coordination is stronger than the coordination between the pyranone functional group and rare earth elements, thus exhibiting excellent selective aluminum removal performance. Simultaneously, the pyranone functional group possesses acid-base properties, enabling it to undergo ion exchange reactions or physical adsorption with organic matter, thereby effectively removing TOC from the aquatic environment. Therefore, using the pyranone-based chelating resin provided in this application, the synergistic effect of multi-oxygen coordination and selective ion exchange capacity can efficiently remove aluminum ions and TOC from rare earth feed solutions, significantly reducing the loss rate of rare earth ions. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic flowchart of a method for preparing a pyranone-based chelating resin in one embodiment;

[0046] Figure 2 This is a schematic flowchart of a method for removing impurities from rare earth slurry in one embodiment;

[0047] Figure 3 This is a synthetic route diagram of the amino resin in Example 1;

[0048] Figure 4 This is a synthetic route diagram of the pyranone-based chelating resin of Example 1;

[0049] Figure 5 The infrared spectrum of the pyranone-based chelating resin in Example 1 is shown below.

[0050] Figure 6 The image shows the adsorption results of the pyranone-based chelating resin in Example 1 after 5 cycles. Detailed Implementation

[0051] To facilitate understanding of this application, the following detailed description is provided in conjunction with specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0053] In this application, "and / or" means any and all combinations of one or more of the related listed items. "At least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two, three, etc., unless otherwise expressly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0054] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0055] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0056] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0057] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0058] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, room temperature can be any of the following temperature ranges: 23℃±2℃, 25℃±5℃, or 20℃±5℃.

[0059] the term

[0060] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0061] In this application, when a substituent of the same symbol appears multiple times, the substituents may be the same or different from each other. If the general formula contains multiple R, then the R may be the same or different from each other.

[0062] "Substituted or unsubstituted" indicates that the defined group may or may not be substituted. When the defined group is substituted, it should be understood that the defined group can be substituted by one or more substituents acceptable in the art, suitable substituents including but not limited to: C1~C1. 30 Alkyl groups, cycloalkyl groups containing 3 to 20 ring atoms, heterocyclic groups containing 3 to 20 ring atoms, aryl groups containing 6 to 20 ring atoms, heteroaryl groups containing 5 to 20 ring atoms, silyl groups, carbonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, carbamoyl groups, haloformyl groups, formyl groups, amino groups, cyano groups, isocyano groups, isocyanate groups, thiocyanate groups, isothiocyanate groups, hydroxyl groups, trifluoromethyl groups, nitro groups, or halogen groups, and the above groups may be further replaced by substituents acceptable in the art.

[0063] "Number of ring atoms" refers to the number of atoms in the ring itself of a compound formed by atomic bonds (e.g., monocyclic compounds, fused-ring compounds, cross-linked compounds, carbocyclic compounds, heterocyclic compounds). When the ring is substituted by a substituent, the atoms contained in the substituent are not included in the ring-forming atoms. The same applies to the "number of ring atoms" as described below unless otherwise specified. For example, the number of ring atoms in a benzene ring is 6, in a naphthalene ring it is 10, and in a thiophene group it is 5.

[0064] "Alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term, such as "C1-C9 alkyl," refer to alkyl groups containing 1 to 9 carbon atoms, and each time it appears, it can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, or C9 alkyl. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(C H3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (- CH2CH2CH(CH3)2), 2-methyl-1-butyl(-CH2CH(CH3)CH2CH3), 1-hexyl(-CH2CH2CH2CH2CH2CH3), 2-hexyl(-CH(CH3)CH2CH2CH2CH3), 3-hexyl(-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl(-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl(-CH(CH3)CH( CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3 and octyl (-(CH2)7CH3).

[0065] "Alkoxy" refers to a group having an -O-alkyl group, i.e., an alkyl group as defined above connected to the parent nucleus via an oxygen atom. Phrases containing this term, such as "C1-C9 alkoxy," refer to alkyl moieties containing 1-9 carbon atoms, and each occurrence can be independently C1 alkoxy, C4 alkoxy, C5 alkoxy, C6 alkoxy, C7 alkoxy, C8 alkoxy, or C9 alkoxy. Suitable examples include, but are not limited to: methoxy (-O-CH3 or -OMe), ethoxy (-O-CH2CH3 or -OEt), and tert-butoxy (-OC(CH3)3 or -OtBu).

[0066] "Alkenyl" refers to a group containing at least one unsaturated site, i.e., carbon-carbon sp. 2 Hydrocarbons with a double bond consisting of a positive, secondary, tertiary, or cyclic carbon atom. Phrases containing this term, such as "C2-C9 alkenyl," refer to alkenyl groups containing 2 to 9 carbon atoms, which, each time appearing, can independently be C2-alkenyl, C3-alkenyl, C4-alkenyl, C5-alkenyl, C6-alkenyl, C7-alkenyl, C8-alkenyl, or C9-alkenyl. Suitable examples include, but are not limited to: vinyl (-CH=CH2), allyl (-CH2CH=CH2), cyclopentenyl (-C5H7), and 5-hexenyl (-CH2CH2CH2CH2CH=CH2).

[0067] "Alynyl" refers to a hydrocarbon containing at least one unsaturated carbon atom, namely a carbon-carbon sp triple bond, or a carbon atom of the same type (positive, secondary, tertiary, or cyclic). Phrases containing this term, such as "C2-C9 alynyl," refer to alkynyl groups containing 2 to 9 carbon atoms, and each occurrence can be independently C2-alkynyl, C3-alkynyl, C4-alkynyl, C5-alkynyl, C6-alkynyl, C7-alkynyl, C8-alkynyl, or C9-alkynyl. Suitable examples include, but are not limited to, ethynyl (-C≡CH) and propynyl (-CH2C≡CH).

[0068] "Aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. It can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic compounds, at least one ring must be an aromatic ring system. For example, "C5~C..." 20 "Aryl" refers to an aryl group containing 5 to 20 carbon atoms. Each time it appears, it can independently be C5 aryl, C6 aryl, C7 aryl, C8 aryl, C9 ... 10 Aryl, C 14 Aryl, C 18 Aryl or C 20 Aryl groups. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene and their derivatives.

[0069] "Halogen" refers to F, Cl, Br or I.

[0070] "Hydroxy group" refers to -OH.

[0071] "Thiol group" refers to -SH.

[0072] The "carboxyl group" refers to -COOH.

[0073] "Ester group" refers to a monovalent residue with the general formula -COOR, wherein R is selected from substituted or unsubstituted alkyl groups, substituted or unsubstituted cycloalkyl groups, substituted or unsubstituted heterocyclic groups, etc. Suitable examples include, but are not limited to: methyl ester group (methyl ester group, -COOCH3), ethyl ester group (ethyl ester group, -COOCH2CH3).

[0074] "Amino" refers to a derivative of ammonia, which has the structural feature of the formula -N(X)2, wherein each "X" is independently H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, etc.

[0075] "White spheres" refer to styrene-divinylbenzene copolymers in styrene-based adsorption resins. By subjecting the white spheres to a chloromethylation reaction, -CH2Cl active groups are introduced into the adsorption resin. This type of styrene-based adsorption resin with -CH2Cl active groups is called a "chlorine sphere".

[0076] "Swelling" refers to the phenomenon that polymers, such as white spheres, chlorinated spheres, and amino resins, expand in volume after being soaked in a solvent, which can make the molecular structure of the polymer looser.

[0077] Aluminum is the most common impurity element in rare earth solutions. The coexistence of aluminum and rare earth elements presents the following problems: (1) it increases the amount of precipitant used in subsequent separation and purification processes; (2) it reduces the extraction capacity of the solvent and forms stable complexes with the extract, leading to emulsification; (3) it affects the performance of rare earth products, for example, the presence of aluminum reduces the saturation magnetization and magnetic anisotropy of neodymium iron boron (NdFeB) magnets. Therefore, separating aluminum ions from rare earth resources is particularly important in industrial production processes.

[0078] Currently, the main methods for removing aluminum from rare earth solutions are selective precipitation and solvent extraction. Selective precipitation is a mature and simple process with a large throughput, but it requires large amounts of precipitating agents (such as oxalic acid, ammonium bicarbonate, and ammonia), resulting in high rare earth element loss and low aluminum removal rates. Solvent extraction offers advantages such as high separation efficiency, good continuous production rate, and large production capacity. However, the extraction process also involves the use of large amounts of organic solvents. This leads to an increase in the total organic carbon (TOC) content of the rare earth solution, affecting subsequent rare earth element extraction. Furthermore, the volatility and corrosiveness of organic solvents have significant negative impacts on equipment, the environment, and personnel.

[0079] Total Organic Carbon (TOC) refers to the total carbon content of all organic matter in water and is one of the important parameters for evaluating water quality. TOC can originate from natural processes (such as plant decay) or human activities (such as industrial wastewater discharge). Excessive TOC levels can pollute water bodies, affecting the taste and odor of the water, and may even produce harmful disinfection byproducts. Therefore, removing TOC from aquatic environments such as rare earth solutions is essential.

[0080] Currently, methods for removing TOC mainly include advanced oxidation technologies, membrane separation technologies, and biological treatment technologies. Advanced oxidation technologies, including ozone oxidation, ultraviolet oxidation, and the Fenton reaction, all remove TOC by oxidizing organic matter into carbon dioxide and water. While widely applicable, they require expensive equipment and operating costs, are energy-intensive, and operate under demanding conditions. Membrane separation technologies suffer from membrane fouling, requiring frequent replacements and resulting in high costs. External pressure on the membrane also increases energy consumption and costs. Biological treatment technologies have relatively low operating costs, relying primarily on the natural degradation by microorganisms. However, biological treatment processes are time-consuming, making them unsuitable for applications requiring rapid processing, and the microorganisms are highly susceptible to environmental factors.

[0081] Therefore, traditional methods for removing aluminum and TOC from rare earth solutions often suffer from problems such as high rare earth element loss rates, low aluminum removal rates, and low TOC removal rates.

[0082] Based on this, in a first aspect, this application provides a pyranone-based chelating resin.

[0083] In some embodiments, the pyranone-based chelating resin has a structure as shown in general formula (I):

[0084] (I); (Ⅱ-1); (Ⅱ-2);

[0085] Where n is selected from positive integers;

[0086] R1 and R2 are each independently selected from H, the structure shown in general formula (II-1), and the structure shown in general formula (II-2), and R1 and R2 are not simultaneously selected from H;

[0087] Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

[0088] In this application, pyrone, with the chemical formula C5H4O2, is a class of six-membered oxygen-containing heterocyclic compounds. Based on the positions of the double bonds and carbonyl groups in the ring, it can be divided into two isomers: α-pyrone and γ-pyrone, with structures shown in general formula (III-1) or general formula (III-2), respectively.

[0089] (Ⅲ-1); (Ⅲ-2);

[0090] The ring of pyranone groups has two double bonds and two oxygen atoms (one carbonyl and one ether bond), which can participate in a variety of chemical reactions such as nucleophilic addition reactions, acid-base reactions and redox reactions. It has antibacterial, antiviral, anti-inflammatory, antitumor and antioxidant effects, and has wide applications in pharmaceuticals, fragrances, dyes, pesticides and materials science.

[0091] The pyranone-based chelating resin provided in this application has a styrene-based adsorption resin backbone with at least one pyranone functional group branched onto its side links. The multi-oxygen structure of the pyranone functional group and the nitrogen atom on the backbone can strongly coordinate with aluminum ions, forming a stable six-membered ring chelate through a chelation reaction. This coordination is stronger than the coordination between the pyranone functional group and rare earth elements, thus exhibiting excellent selective aluminum removal performance. Simultaneously, the pyranone functional group possesses acid-base properties, enabling it to undergo ion exchange reactions or physical adsorption with organic matter, thereby effectively removing TOC from the aquatic environment. Therefore, using the pyranone-based chelating resin provided in this application, the synergistic effect of multi-oxygen coordination and selective ion exchange capacity can efficiently remove aluminum ions and TOC from rare earth feed solutions, significantly reducing the loss rate of rare earth ions.

[0092] In this application, in the structure shown in general formula (I), n is selected from positive integers. In some embodiments, n is selected from positive integers between 1 and 1000, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, 200, 300, 400, 500 or 1000.

[0093] In this application, the structure represented by general formula (Ⅱ-1) represents an α-pyranone functional group, and the structure represented by general formula (Ⅱ-2) represents a γ-pyranone functional group. That is, R1 and R2 are each independently selected from H, an α-pyranone functional group, and a γ-pyranone functional group, and R1 and R2 are not both selected from H. Suitable combinations can be: H and an α-pyranone functional group; H and a γ-pyranone functional group; an α-pyranone functional group and an α-pyranone functional group; an α-pyranone functional group and a γ-pyranone functional group; or a γ-pyranone functional group and a γ-pyranone functional group.

[0094] In some embodiments, R1 and / or R2 are selected from structures shown in general formula (II-2). The γ-pyranone functional group can abstract a proton in water, exhibiting strong basicity. Simultaneously, the oxygen atom on its ring contains a lone pair of electrons, enabling conjugation with the double bond, resulting in high structural stability. Furthermore, during salt formation, the proton combines with the carbonyl oxygen atom to form a closed aromatic conjugated system, enhancing the stability of the salt products. Therefore, the side-linked branches of the pyranone-based chelating resin have at least one γ-pyranone functional group, exhibiting stronger coordination ability for aluminum ions and ion exchange capacity for TOC, further improving the removal rates of aluminum ions and TOC.

[0095] In this application, each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl. Further, each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 alkenyl, substituted or unsubstituted C1-C6 alkynyl, and substituted or unsubstituted C6-C6 alkynyl. 12 One of the aryl groups. Furthermore, each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, C1-C6 alkyl, hydroxyl-substituted C1-C6 alkyl, and C1-C6 alkoxy groups.

[0096] In some embodiments, R3 and R4 each appear independently selected from one of H, hydroxyl, carboxyl, C1-C3 alkyl, hydroxyl-substituted C1-C3 alkyl, and C1-C3 alkoxy.

[0097] Understandably, "C1~C3 alkyl" can be C1 alkyl, C2 alkyl, or C3 alkyl. "Hydroxy-substituted C1~C3 alkyl" means that at least one hydrogen atom on the C1~C3 alkyl group is substituted by a hydroxyl group. "C1~C3 alkoxy" can be C1 alkoxy, C2 alkoxy, or C3 alkoxy.

[0098] In some embodiments, R3 and R4 are each independently selected from one of H, hydroxyl (-OH), carboxyl (-COOH), methyl (-CH3), hydroxymethyl (-CH2OH), and methoxy (-OCH3).

[0099] In some embodiments, R1 and / or R2 are selected from at least one of the structures shown in general formula (II-3) and general formula (II-4):

[0100] (Ⅱ-3); (Ⅱ-4).

[0101] In some embodiments, the adsorption capacity of the pyranone-based chelating resin for TOC is ≥1800 mg / g, including but not limited to 1800 mg / g, 1900 mg / g, 2000 mg / g, 2100 mg / g, 2200 mg / g, 2300 mg / g, 2400 mg / g, 2500 mg / g, 2600 mg / g, 2700 mg / g, 2800 mg / g, 2900 mg / g, or 3000 mg / g. Further, the adsorption capacity of the pyranone-based chelating resin for TOC is 1800 mg / g to 3000 mg / g.

[0102] In some embodiments, under conditions where the TOC content is 100±5ppm, the pyranone-based chelating resin achieves a TOC removal rate of ≥48%, including but not limited to 48%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%. Further, under conditions where the TOC content is 100±5ppm, the pyranone-based chelating resin achieves a TOC removal rate of ≥90%.

[0103] In some embodiments, the adsorption capacity of the pyranone-based chelating resin for aluminum ions is ≥20 mg / g, including but not limited to 20 mg / g, 21 mg / g, 22 mg / g, 23 mg / g, 24 mg / g, 25 mg / g, 26 mg / g, 27 mg / g, 28 mg / g, 29 mg / g, or 30 mg / g. Further, the adsorption capacity of the pyranone-based chelating resin for aluminum ions is 20 mg / g to 30 mg / g.

[0104] In some embodiments, under conditions where the aluminum ion content is 110±10 ppm, the pyranone-based chelating resin achieves an aluminum ion removal rate of ≥50%, including but not limited to 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%. Further, under conditions where the aluminum ion content is 110±10 ppm, the pyranone-based chelating resin achieves an aluminum ion removal rate of ≥85%.

[0105] In some embodiments, the adsorption capacity of the pyranone-based chelating resin for rare earth ions is ≤0.02 mg / g, including but not limited to 0.001 mg / g, 0.005 mg / g, 0.01 mg / g, 0.015 mg / g, or 0.02 mg / g.

[0106] In some embodiments, under the condition of a rare earth ion content of 1080±100ppm, the removal rate of rare earth ions by the pyranone-based chelating resin is ≤49%, including but not limited to 1%, 2%, 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 49%. Further, under the condition of a rare earth ion content of 1080±100ppm, the removal rate of rare earth ions by the pyranone-based chelating resin is ≤8%.

[0107] In a second aspect, this application provides a method for preparing a pyranone-based chelating resin, used to synthesize the pyranone-based chelating resin as described above.

[0108] In some embodiments, the preparation method of the pyranone-based chelating resin includes the following steps:

[0109] Amino resins, pyranone compounds, and aldehyde compounds are subjected to the Mannich reaction to obtain pyranone-based chelating resins;

[0110] Amino resins have the structure shown in general formula (Ⅳ), pyranone compounds have the structure shown in general formula (Ⅴ-1) or general formula (Ⅴ-2), and aldehyde compounds include formaldehyde or paraformaldehyde;

[0111] (Ⅳ); (V-1); (V-1);

[0112] Where n is a positive integer;

[0113] Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or substituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

[0114] In this application, the Mannich reaction, also known as the Mannich reaction or Mannich reaction, refers to an organic synthesis reaction in which a compound containing active hydrogen (usually a carbonyl compound) undergoes a condensation reaction with an amine or formaldehyde to produce a β-amino compound. The β-amino compound produced by the reaction can be called a Mannich base (or Mannich base, Mannich base).

[0115] In the preparation method provided in this application, the α-hydrogen near the carbonyl group of the pyranone compound provides a Mannich reaction site, which can directly undergo a condensation reaction with amino resins, formaldehyde, or paraformaldehyde to generate a pyranone-based chelating resin with high aluminum ion and TOC removal rates and low rare earth ion loss rates in one step. Simultaneously, this preparation method avoids functionalization treatments such as chloromethylation of the pyranone compound, reducing the impact on R3 and R4, which is beneficial for improving its ion exchange capacity. Furthermore, it can increase the grafting rate of pyranone functional groups onto the resin framework, which is beneficial for improving its adsorption performance for aluminum ions and TOC. In addition, this preparation method uses a one-step synthesis of pyranone-based chelating resin, which can improve the yield of pyranone-based chelating resin, reduce cumbersome steps such as separation and purification, greatly shorten the synthesis cycle, conform to the principles of green chemistry, reduce the risk of environmental pollution, and uses inexpensive and readily available raw materials under relatively mild reaction conditions. It has the advantages of being environmentally friendly, easy to implement, and suitable for industrial application.

[0116] Please see Figure 1 This is a schematic flowchart illustrating the preparation method of the pyranone-based chelating resin in one embodiment. Figure 1 As shown, the preparation method of pyranone-based chelating resin includes the following steps:

[0117] S11: Preparation of amino resins;

[0118] S12: Perform the Mannich reaction on amino resins, pyranone compounds, and aldehyde compounds to obtain pyranone-based chelating resins.

[0119] The preparation method of pyranone-based chelating resin is described in detail below using a step-by-step approach.

[0120] S11: Preparation of amino resin.

[0121] Understandably, amino resins have a structure as shown in general formula (Ⅳ), where n in general formula (Ⅳ) is selected from positive integers. In some embodiments, n is selected from positive integers between 1 and 1000, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, 200, 300, 400, 500, or 1000.

[0122] In some embodiments, optionally, the nitrogen content of the amino resin is 15 at.% to 25 at.%, including but not limited to 15 at.%, 16 at.%, 17 at.%, 18 at.%, 19 at.%, 20 at.%, 21 at.%, 22 at.%, 23 at.%, 24 at.%, or 25 at.%. This increases the amino content on the amino resin, thereby increasing the grafting rate of pyranone functional groups onto the resin backbone, and thus improving the removal efficiency of aluminum ions and TOC.

[0123] In some embodiments, the preparation method of the amino resin includes the Gabriel synthesis method.

[0124] Understandably, the Gabriel synthesis is a method for synthesizing primary amines. It involves reacting potassium phthalimide with a haloalkane to generate an N-alkylated phthalimide (i.e., an intermediate), which is then decomposed (e.g., by hydrolysis or hydrazolysis) to yield the primary amine and phthalic acid. The hydrolysis can be performed under acidic or basic conditions.

[0125] In some embodiments, the method for preparing amino resin includes the following steps:

[0126] A mixture of chlorine beads, a first solvent, and potassium phthalimide was heated to react and yield an intermediate.

[0127] A mixture of intermediates and decomposition reagents is carried out to decompose the resin and prepare an amino resin.

[0128] In some embodiments, mixing chlorine beads, a first solvent, and potassium phthalimide includes the following steps: mixing the chlorine beads and the first solvent, performing a first swelling reaction, and adding potassium phthalimide. Thus, through the first swelling reaction, the molecular structure of the chlorine beads becomes looser, allowing potassium phthalimide to easily enter the interior of the chlorine beads for reaction, thereby accelerating the reaction rate and improving reaction uniformity.

[0129] In some embodiments, the conditions for the first swelling reaction include swelling at 20°C to 40°C for 2 hours to 6 hours. The temperature of the first swelling reaction can be 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, or 40°C, and the duration of the first swelling reaction can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0130] In some embodiments, the first solvent is a highly polar organic solvent, including but not limited to at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), ethanol (EtOH), acetonitrile (MeCN), and acetone, and further optionally DMF.

[0131] In some embodiments, the mass ratio of chlorine beads to the first solvent is 1:(1~5), including but not limited to 1:1, 1:2, 1:3, 1:4 or 1:5.

[0132] In some embodiments, the mass ratio of chlorine bulbs to potassium phthalimide is 1:(0.8~1.2), including but not limited to 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2.

[0133] In some embodiments, the conditions for the heating reaction include: reflux reaction at 80°C to 120°C for 6 to 12 hours. The heating temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C, and the heating time can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0134] In some embodiments, the decomposing agent includes at least one selected from ethanolamine, a methylamine halide, and hydrazine hydrate. The ethanolamine includes at least one selected from monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA). The methylamine halide includes at least one selected from methylamine hydrochloride, methylamine hydrobromide, and methylamine hydroiodide. Further, the decomposing agent is monoethanolamine (MEA).

[0135] In some embodiments, the mass ratio of chlorine balls to decomposition reagent is 1:(1~2.4), including but not limited to: 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2 or 1:2.4.

[0136] In some embodiments, the decomposition reaction conditions include reflux reaction at 60°C to 120°C for 6 to 12 hours. The decomposition reaction temperature can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, and the decomposition reaction time can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0137] In some embodiments, the decomposition reaction is carried out in a second solvent, which is a highly polar organic solvent, including but not limited to at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), ethanol (EtOH), acetonitrile (MeCN), and acetone, and further optionally ethanol (EtOH).

[0138] In some embodiments, the mass ratio of the chlorine ball to the second solvent is 1:(1~5), including but not limited to 1:1, 1:2, 1:3, 1:4 or 1:5.

[0139] In some embodiments, after the heating reaction and / or after the decomposition reaction, a first purification step is further included. The first purification step includes at least one of filtration, washing, distillation, and drying; filtration may be ordinary filtration, vacuum filtration, or pressure filtration; washing may be ordinary washing, ultrasonic washing, or Soxhlet extraction, and the washing solution may be pure water, deionized water, methanol, ethanol, or acetone; the drying method includes forced-air drying or vacuum drying.

[0140] In some embodiments, after the heating reaction, the method further includes the following steps: filtering the mixed solution containing the intermediate, washing the resulting filter residue several times with ethanol and pure water to obtain the intermediate.

[0141] In some embodiments, after the decomposition reaction, the method further includes the following steps: filtering the mixed solution containing amino resin, performing Soxhlet extraction on the resulting filter residue with ethanol for 10-16 hours, and drying at 40-60°C for 3-6 hours. The Soxhlet extraction time can be 10, 11, 12, 13, 14, 15, or 16 hours, the drying temperature can be 40, 45, 50, 55, or 60°C, and the drying time can be 3, 4, 5, or 6 hours.

[0142] S12: Perform the Mannich reaction on amino resins, pyranone compounds, and aldehyde compounds to obtain pyranone-based chelating resins.

[0143] Understandably, pyranone compounds have structures as shown in general formula (V-1) or general formula (V-2). Each time R3 and R4 appear, they are each independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl. Further, each time R3 and R4 appear, they are each independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 alkenyl, substituted or unsubstituted C1-C6 alkynyl, and substituted or unsubstituted C6-C6 alkyl. 12 One of the aryl groups. Furthermore, each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, C1-C6 alkyl, hydroxyl-substituted C1-C6 alkyl, and C1-C6 alkoxy groups.

[0144] In some embodiments, R3 and R4 each appear independently selected from one of H, hydroxyl, carboxyl, C1-C3 alkyl, hydroxyl-substituted C1-C3 alkyl, and C1-C3 alkoxy.

[0145] Understandably, "C1~C3 alkyl" can be C1 alkyl, C2 alkyl, or C3 alkyl. "Hydroxy-substituted C1~C3 alkyl" means that at least one hydrogen atom on the C1~C3 alkyl group is substituted by a hydroxyl group. "C1~C3 alkoxy" can be C1 alkoxy, C2 alkoxy, or C3 alkoxy.

[0146] In some embodiments, R3 and R4 are each independently selected from one of H, hydroxyl (-OH), carboxyl (-COOH), methyl (-CH3), hydroxymethyl (-CH2OH), and methoxy (-OCH3).

[0147] In some embodiments, the pyranone compound includes at least one selected from 5-hydroxy-2-hydroxymethyl-4-pyranone, 3-hydroxy-2-methyl-4-pyranone, 5-methoxy-2-hydroxymethyl-4-pyranone, 4-methoxy-6-methyl-2-pyranone, and 2-pyranone-5-carboxylic acid. The 5-hydroxy-2-hydroxymethyl-4-pyranone has the structure shown in general formula (V-3), and the 5-methoxy-2-hydroxymethyl-4-pyranone has the structure shown in general formula (V-4).

[0148] (V-3); (V-4).

[0149] In some embodiments, an amino resin, a pyranone compound, and an aldehyde compound are subjected to a Mannich reaction, comprising the following steps: mixing the pyranone compound, the amino resin, the aldehyde compound, and a third solvent; heating to 60°C–100°C; adding a catalyst; and refluxing for 6–12 hours to obtain a pyranone-based chelating resin. The Mannich reaction temperature can be 60°C, 70°C, 80°C, 90°C, or 100°C, and the Mannich reaction time can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0150] In some embodiments, the third solvent includes a protic solvent. The protic solvent includes at least one selected from water, methanol, ethanol, isopropanol, ethylene glycol, and glycerol.

[0151] In some embodiments, the catalyst comprises at least one of an inorganic acid and an inorganic base. The inorganic acid includes at least one of hydrochloric acid, sulfuric acid, and nitric acid, and the inorganic base includes at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0152] In some embodiments, the mass ratio of amino resin, pyranone compound, and aldehyde compound is 1:(1~3):(0.15~0.45). The mass ratio of amino resin to pyranone compound can be 1:1, 1:1.5, 1:2, 1:2.5, or 1:3, and the mass ratio of amino resin to aldehyde compound can be 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, or 1:0.45.

[0153] In some embodiments, the mass ratio of amino resin, catalyst, and third solvent is 1:(0.1~0.3):(4~6). The mass ratio of amino resin to catalyst can be 1:0.1, 1:0.15, 1:0.2, 1:0.25, or 1:0.3, and the mass ratio of amino resin to third solvent can be 1:4, 1:4.5, 1:5, 1:5.5, or 1:6.

[0154] In some embodiments, after the Mannich reaction, a second purification step is further included. The second purification step includes at least one of filtration, washing, distillation, and drying; filtration may be ordinary filtration, vacuum filtration, or pressure filtration; washing may be ordinary washing, ultrasonic washing, or Soxhlet extraction, and the washing solution may be pure water, deionized water, methanol, ethanol, or acetone; the drying method includes forced-air drying or vacuum drying.

[0155] In some embodiments, after the Mannich reaction, the method further includes the following steps: filtering the mixed solution containing pyranone chelating resin, performing Soxhlet extraction on the resulting filter residue with ethanol for 10-16 hours, and drying at 40-60°C for 3-6 hours. The Soxhlet extraction time can be 10, 11, 12, 13, 14, 15, or 16 hours, the drying temperature can be 40, 45, 50, 55, or 60°C, and the drying time can be 3, 4, 5, or 6 hours.

[0156] In a third aspect, this application provides a method for removing impurities from rare earth liquid, which is the application of the above-mentioned pyranone-based chelating resin in the field of rare earth product technology.

[0157] In some embodiments, the method for removing impurities from rare earth solutions includes the following steps: using the above-mentioned pyranone-based chelating resin, or the pyranone-based chelating resin prepared by the above-mentioned method, to adsorb the rare earth solution to remove aluminum ions and TOC from the rare earth solution.

[0158] This application utilizes the synergistic effect of the multi-oxygen coordination effect and the selective ion exchange capacity of pyranone-based chelating resin to efficiently remove aluminum ions and TOC from rare earth feed solutions, significantly reducing the loss rate of rare earth ions. Furthermore, the pyranone-based chelating resin is easily regenerated and can be recycled for extended periods, reducing the cost of impurity removal from rare earth feed solutions.

[0159] Please see Figure 2 This is a schematic flowchart of a method for removing impurities from a rare earth liquid sample in one embodiment. Figure 2 As shown, the method for removing impurities from rare earth slurry includes the following steps:

[0160] S21: Pyranone chelating resin is packed into a chromatography column and pretreated with water to obtain a blank column;

[0161] S22: The rare earth solution is passed through a blank column for adsorption treatment to obtain an adsorption solution and an adsorption column.

[0162] S23: Desorb the adsorption column using acid solution to obtain desorption solution and desorption column;

[0163] S24: The desorption column is regenerated using water to obtain a blank column.

[0164] This application packs pyranone-based chelating resin into a chromatography column, utilizes the separation principle of the chromatographic column to remove impurities from rare earth feed solutions, and uses acid for desorption and water for regeneration, enabling the pyranone-based chelating resin to be recycled, thus having broad industrial application prospects.

[0165] In some embodiments, the height-to-diameter ratio of the chromatography column is 8 to 20, for example, 8, 10, 12, 14, 16, 18 or 20.

[0166] In some embodiments, the amount of rare earth feed solution used in the adsorption treatment is 1.5 BV to 9 BV, for example, 1.5 BV, 2 BV, 3 BV, 4 BV, 5 BV, 6 BV, 7 BV, 8 BV or 9 BV; the flow rate of the rare earth feed solution is 1 BV / h to 5 BV / h, for example, 1 BV / h, 2 BV / h, 3 BV / h, 4 BV / h or 5 BV / h.

[0167] In some embodiments, during the desorption process, the amount of acid used is 2BV to 6BV, for example, 2BV, 3BV, 4BV, 5BV or 6BV; the flow rate of the acid is 1BV / h to 5BV / h, for example, 1BV / h, 2BV / h, 3BV / h, 4BV / h or 5BV / h.

[0168] In some embodiments, the mass fraction of acid in the acid solution is 5% to 15%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0169] In some embodiments, the acid in the acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0170] In some embodiments, the water used in the pretreatment and / or regeneration processes can be pure water or deionized water; the water volume is 2 BV to 5 BV, for example, 2 BV, 3 BV, 4 BV or 5 BV; the water flow rate is 1 BV / h to 5 BV / h, for example, 1 BV / h, 2 BV / h, 3 BV / h, 4 BV / h or 5 BV / h.

[0171] In some embodiments, the mass ratio of rare earth elements to aluminum ions in the rare earth solution is (8~12):1, for example, it can be 8:1, 9:1, 10:1, 11:1 or 12:1. Further, the aluminum ion content in the rare earth solution is 110±10ppm and the rare earth ion content is 1080±100ppm.

[0172] In some embodiments, the TOC content in the rare earth solution is 100±5ppm.

[0173] In some embodiments, the rare earth feed solution is acidic. Further, the pH of the rare earth feed solution is 1 to 4, for example, it can be 1, 1.5, 2, 2.5, 3, 3.5 or 4.

[0174] The following detailed description is provided in conjunction with specific embodiments and comparative examples. Unless otherwise specified, all raw materials and instruments used in these embodiments and comparative examples are commercially available. Unless otherwise specified, all processes involved are conventionally chosen by those skilled in the art. Specifically, the chloroform was purchased from Wandong High-Tech (Tianchang) Co., Ltd. (LQ-117 chloroform). Other reagents, including potassium phthalimide, ethanolamine, pyranone compounds, paraformaldehyde, and solvents, were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and were used directly without further purification.

[0175] Example 1

[0176] Please see Figure 3 and Figure 4 ,in, Figure 3 This is a synthesis route diagram of the amino resin in this embodiment. Figure 4This is a synthetic route diagram of the pyranone-based chelating resin of this embodiment. Compound 11 is a chlorosphere, compound 12 is an N-alkyl phthalimide (i.e., an intermediate), compound 13 is an amino resin, compound 14 is a pyranone compound (5-hydroxy-2-hydroxymethyl-4-pyranone), compound 15 is paraformaldehyde (m is selected from positive integers), and compounds 16 and 17 are the pyranone-based chelating resin obtained in Example 1.

[0177] The preparation method of the pyranone-based chelating resin in this embodiment includes the following steps:

[0178] (1) Preparation of amino resin:

[0179] Chlorinated spheres were swollen in N,N-dimethylformamide (DMF) for 4 hours, potassium phthalimide was added, the mixture was heated to 100°C, and refluxed for 8 hours to obtain a mixed solution containing the intermediate. The solution was filtered, and the residue was washed several times with ethanol and pure water to obtain the intermediate. The mass ratio of chlorinated spheres, potassium phthalimide, and DMF was 1:1:4.

[0180] A mixture of intermediate, monoethanolamine (MEA), and ethanol was heated to 80°C and refluxed for 12 hours to allow the intermediate to undergo hydrolysis, yielding a mixed solution containing amino resin. The solution was then subjected to Soxhlet extraction with ethanol for 12 hours and dried at 60°C for 6 hours to obtain the amino resin. The mass ratio of chloroform, ethanolamine, and ethanol was 1:2.4:5.

[0181] (2) Preparation of pyranone chelating resin:

[0182] A mixture of amino resin, pyranone compound (5-hydroxy-2-hydroxymethyl-4-pyranone), paraformaldehyde, and ethanol was heated to 80°C, and a catalyst (concentrated sulfuric acid) was added. The mixture was refluxed for 12 hours to allow the amino resin, pyranone compound, and paraformaldehyde to undergo a Mannich reaction, yielding a mixed solution containing pyranone-based chelating resin. The solution was then subjected to Soxhlet extraction with ethanol for 12 hours, washed with pure water, and dried at 60°C for 6 hours to obtain the pyranone-based chelating resin. The mass ratio of amino resin, pyranone compound, and paraformaldehyde was 1:2:0.3, and the mass ratio of amino resin, catalyst, and ethanol was 1:0.1:5.

[0183] Example 2

[0184] This embodiment is basically the same as Example 1, except that the pyranone compound is replaced with an equal mass of 5-methoxy-2-hydroxymethyl-4-pyranone.

[0185] Example 3

[0186] This embodiment is basically the same as Embodiment 1, except that the reaction conditions in step (2) are different, as follows:

[0187] A mixture of amino resin, pyranone compound (5-hydroxy-2-hydroxymethyl-4-pyranone), paraformaldehyde, and methanol was heated to 60°C, and a catalyst (sodium hydroxide) was added. The mixture was refluxed for 12 hours to allow the amino resin, pyranone compound, and paraformaldehyde to undergo a Mannich reaction, yielding a mixed solution containing pyranone-based chelating resin. The solution was then subjected to Soxhlet extraction with methanol for 12 hours, washed with pure water, and dried at 60°C for 6 hours to obtain the pyranone-based chelating resin. The mass ratio of amino resin, pyranone compound, and paraformaldehyde was 1:2:0.3, and the mass ratio of amino resin, catalyst, and methanol was 1:0.1:5.

[0188] Example 4

[0189] This embodiment is basically the same as Embodiment 1, except that the reaction conditions in step (2) are different, as follows:

[0190] A mixture of amino resin, pyranone compound (5-hydroxy-2-hydroxymethyl-4-pyranone), paraformaldehyde, and methanol was heated to 60°C, and a catalyst (concentrated sulfuric acid) was added. The mixture was refluxed for 12 hours to allow the amino resin, pyranone compound, and paraformaldehyde to undergo a Mannich reaction, yielding a mixed solution containing pyranone-based chelating resin. The solution was then subjected to Soxhlet extraction with methanol for 12 hours, washed with pure water, and dried at 60°C for 6 hours to obtain the pyranone-based chelating resin. The mass ratio of amino resin, pyranone compound, and paraformaldehyde was 1:2:0.3, and the mass ratio of amino resin, catalyst, and methanol was 1:0.1:5.

[0191] Example 5

[0192] This embodiment is basically the same as Example 1, except that the mass ratio of amino resin, pyranone compound and paraformaldehyde is 1:1:0.15.

[0193] Example 6

[0194] This embodiment is basically the same as Example 1, except that the mass ratio of amino resin, pyranone compound and paraformaldehyde is 1:3:0.45.

[0195] Comparative Example 1

[0196] This comparative example uses a commercially available aminocarboxylic acid adsorption resin for aluminum removal, with the following structure:

[0197] .

[0198] Comparative Example 2

[0199] This comparative example uses a commercially available polyhydroxyglucose adsorption resin for TOC removal, with the following structure:

[0200] .

[0201] Comparative Example 3

[0202] This comparative example uses a pyranone-based chelating resin with the following structure:

[0203] .

[0204] Test case

[0205] 1. Infrared Spectrum: The pyranone-based chelating resin of Example 1 was characterized by infrared spectroscopy, and the results are as follows: Figure 5 As shown. In Figure 5 Middle, 3251cm -1 The infrared absorption peak at 1620 cm⁻¹ belongs to the stretching vibration peak of the hydroxyl group on the pyranone functional group. The conjugation effect of the two carbon-carbon double bonds causes the infrared absorption peak of the carbonyl group on the pyranone functional group to shift to a lower wavenumber. -1 The characteristic peaks at the location are attributed to the carbonyl stretching vibration peaks on the pyranone functional group, which indicates that the main chain skeleton of the pyranone chelating resin of Example 1 is grafted with pyranone functional groups having the structure shown in general formula (Ⅱ-3).

[0206] 2. Adsorption performance test:

[0207] (1) Packing and pretreatment: 10 mL of pyranone chelating resin was packed into a chromatography column with a height-to-diameter ratio of 10. The column was pretreated with pure water at a volume of 5 BV and a flow rate of 1 BV / h to obtain a blank column.

[0208] (2) Adsorption: The rare earth solution is injected from one end and flows through the blank column for adsorption treatment. The volume of the rare earth solution is 10 BV and the flow rate of the rare earth solution is 1 BV / h. The adsorption column and adsorption solution are obtained.

[0209] (3) Desorption: A 10% hydrochloric acid solution was flowed through the adsorption column for desorption treatment. The volume of the hydrochloric acid solution was 5 BV and the flow rate of the hydrochloric acid solution was 1 BV / h. Each 1 BV of desorbed solution was retained to obtain the desorption column and the desorbed solution.

[0210] (4) Regeneration: Pure water is used to regenerate the column by flowing through it. The volume of pure water is 5 BV and the flow rate is 1 BV / h to obtain a blank column.

[0211] (5) Repeat steps (2) to (4) for a total of 5 cycles.

[0212] The rare earth ion and aluminum ion contents in the rare earth feed solution (pH=3) and adsorption solution during the first cycle were tested using ICP-MS, and the TOC content was determined using a TOC analyzer. The results are listed in Table 1. The formula for calculating the loss rate or removal rate is: (content of rare earth feed solution - content of adsorption solution) ÷ content of rare earth feed solution × 100%.

[0213] Table 1. Adsorption effect of pyranone-based chelating resin on rare earth solution

[0214]

[0215] As can be clearly seen from Table 1 above, when the pyranone-based chelating resins prepared in Examples 1 to 6 of this application are used for the adsorption treatment of rare earth solutions, the removal rate of aluminum ions reaches more than 50%, the removal rate of TOC reaches more than 48%, and the loss rate of rare earth ions is reduced to less than 49%. This shows that the pyranone-based chelating resins provided in this application can selectively remove impurities such as aluminum ions and TOC, and effectively avoid the loss of rare earth resources.

[0216] As can be seen from Examples 1, 5 and 6, increasing the amount of pyranone compound during the Mannich reaction is beneficial to improving the grafting rate of pyranone functional groups on the resin skeleton, thereby improving the adsorption effect of pyranone-based chelating resin on aluminum ions and TOC.

[0217] Using concentrated sulfuric acid as a catalyst, the resulting pyranone-based chelating resin is an H-type resin. A comparison of Examples 1 and 4 shows that the Mannich reaction temperature in Example 4 was lower, resulting in a lower reaction rate and a decreased grafting rate of the pyranone functional groups, thus leading to poorer adsorption of aluminum ions and TOC. Compared to Example 4, Example 3 used NaOH as a catalyst, which accelerated the Mannich reaction rate. The resulting pyranone-based chelating resin is a Na-type resin, exhibiting better adsorption of rare earth ions, aluminum ions, and TOC than the H-type resin, but with reduced selectivity for aluminum ions.

[0218] Compared with Example 1, Comparative Example 1 used aminocarboxylic acid adsorption resin, which achieved a removal rate of 92.67% for aluminum ions, but had a poor removal rate for TOC and a high loss rate for rare earth ions; Comparative Example 2 used polyhydroxyglucose adsorption resin, which achieved a removal rate of 94.90% for TOC, but had a poor removal rate for aluminum ions; In the pyranone chelating resin of Comparative Example 3, the pyranone functional group was linked to the resin skeleton through two -NH- groups, which reduced its adsorption selectivity for aluminum ions and improved its adsorption effect on rare earth ions, thus increasing the loss rate of rare earth ions.

[0219] After each cycle, the TOC removal rate of the pyranone-based chelating resin in Example 1 was tested, and the results are shown in [Figure 1]. Figure 6 .like Figure 6 As shown, after 5 cycles, the TOC removal rate of the pyranone-based chelating resin in Example 1 remained above 92%, demonstrating excellent regeneration and recyclability.

[0220] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0221] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A pyranone-based chelating resin, characterized in that, It has a structure as shown in general formula (Ⅰ): （Ⅰ）； （Ⅱ-1）； （Ⅱ-2）； Where n is selected from positive integers; R1 and R2 are each independently selected from H, the structure shown in general formula (II-1), and the structure shown in general formula (II-2), and R1 and R2 are not simultaneously selected from H; Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

2. The pyranone-based chelating resin according to claim 1, characterized in that, Each time R3 and R4 appear, they are each independently selected from one of H, hydroxyl, carboxyl, C1~C3 alkyl, hydroxyl-substituted C1~C3 alkyl, and C1~C3 alkoxy.

3. The pyranone-based chelating resin according to claim 2, characterized in that, Each time R3 and R4 appear, they are each independently selected from one of H, hydroxyl, carboxyl, methyl, hydroxymethyl, and methoxy groups.

4. The pyranone-based chelating resin according to any one of claims 1 to 3, characterized in that, At least one of the following conditions must be met: (1) The adsorption capacity of the pyranone chelating resin for TOC is ≥1800mg / g; (2) The adsorption capacity of the pyranone chelating resin for aluminum ions is ≥20 mg / g; (3) The adsorption capacity of the pyranone chelating resin for rare earth ions is ≤0.02mg / g.

5. A method for preparing a pyranone-based chelating resin, characterized in that, Includes the following steps: The amino resin, pyranone compound, and aldehyde compound are subjected to a Mannich reaction to obtain the pyranone-based chelating resin. The amino resin has a structure as shown in general formula (Ⅳ), the pyranone compound has a structure as shown in general formula (Ⅴ-1) or general formula (Ⅴ-2), and the aldehyde compound includes formaldehyde or paraformaldehyde; （Ⅳ）； （Ⅴ-1）； （Ⅴ-1）； Where n is a positive integer; Each of R3 and R4 is independently selected from one of H, hydroxyl, carboxyl, ester, mercapto, amino, substituted or substituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, and substituted or unsubstituted aryl.

6. The method for preparing the pyranone-based chelating resin according to claim 5, characterized in that, The pyranone compound includes at least one of 5-hydroxy-2-hydroxymethyl-4-pyranone, 3-hydroxy-2-methyl-4-pyranone, 5-methoxy-2-hydroxymethyl-4-pyranone, 4-methoxy-6-methyl-2-pyranone, and 2-pyranone-5-carboxylic acid.

7. The method for preparing the pyranone-based chelating resin as described in claim 5 or 6, characterized in that, The Mannich reaction of amino resins, pyranone compounds, and aldehyde compounds includes the following steps: The amino resin, the pyranone compound, the aldehyde compound, and a third solvent are mixed, heated to 60°C to 100°C, a catalyst is added, and the mixture is refluxed for 6 to 12 hours to obtain the pyranone-based chelating resin.

8. The method for preparing the pyranone-based chelating resin according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The mass ratio of the amino resin, the pyranone compound, and the aldehyde compound is 1:(1~3):(0.15~0.45); (2) The mass ratio of the amino resin, the catalyst and the third solvent is 1:(0.1~0.3):(4~6); (3) The catalyst includes at least one of an inorganic acid and an inorganic base; (4) The third solvent includes a proton solvent.

9. The method for preparing the pyranone-based chelating resin according to claim 7, characterized in that, The preparation method of the amino resin includes the Gabriel synthesis method.

10. A method for removing impurities from a rare earth slurry, characterized in that, Includes the following steps: Using the pyranone-based chelating resin as described in any one of claims 1 to 4, or the pyranone-based chelating resin prepared by the method described in any one of claims 5 to 9, the rare earth solution is subjected to adsorption treatment to remove aluminum ions and TOC from the rare earth solution.

11. The method for removing impurities from rare earth slurry as described in claim 10, characterized in that, The method for removing impurities from the rare earth slurry includes the following steps: The pyranone-based chelating resin was packed into a chromatography column and pretreated with water to obtain a blank column. The rare earth material solution is passed through the blank column for adsorption treatment to obtain an adsorption solution and an adsorption column. The adsorption column is desorbed using an acid solution to obtain an desorption solution and a desorption column; The desorption column is regenerated using water to obtain the blank column.

12. The method for removing impurities from rare earth slurry as described in claim 11, characterized in that, The following conditions must be met: (1) The height-to-diameter ratio of the chromatography column is 8~20; (2) In the adsorption treatment, the amount of rare earth solution used is 1.5 BV to 9 BV, and the flow rate of rare earth solution is 1 BV / h to 5 BV / h; (3) In the desorption process, the amount of acid used is 2BV~6BV, and the flow rate of acid is 1BV / h~5BV / h; (4) The mass fraction of the acid in the acid solution is 5%~15%; (5) The acid in the acid solution includes at least one of hydrochloric acid, sulfuric acid and nitric acid; (6) In the pretreatment and / or the regeneration treatment, the amount of water used is 2BV to 5BV, and the flow rate of the water is 1BV / h to 5BV / h.

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