Compound, rare-earth element separating agent, and rare-earth element recovering method

Abstract

The present invention addresses the problem of developing a rare-earth element separating agent having higher durability. The present invention provides: a compound in which diglycol amide acid is introduced into a supporting polymer via an alkyl-substituted benzene compound; and a rare-earth element separating agent and a rare-earth element recovering method which use said compound.

Description

Compounds, separation agents for rare earth elements, and methods for recovering rare earth elements.

[0001] The present invention relates to a compound in which diglycolamidic acid is introduced into a supporting polymer via an alkyl-substituted benzene compound, a rare earth element separator utilizing the same, and a method for recovering rare earth elements.

[0002] While there is a need for diversification of rare earth element sources, promising underutilized resources have low rare earth element content and high concentrations of impurities such as iron, making rare earth element recovery difficult. In contrast, it has been found that rare earth elements can be selectively recovered by using an adsorption separation agent that incorporates diglycolamidic acid into the base material (Patent Documents 1 and 2), but the low durability of this adsorption separation agent is a problem. Therefore, there has been a need for the development of a rare earth element separation agent with higher durability.

[0003] Patent No. 6103611 Patent No. 7416059

[0004] As described above, adsorption separation agents incorporating diglycolamidic acid as a base material are promising due to their high selectivity for rare earth elements. However, previously reported adsorption separation agents suffer from low durability. If a highly durable separation agent can be produced, the cost of rare earth element recovery can be reduced, and it will be possible to recover rare earth elements from currently unused resources. In light of this situation, the present invention aims to develop a rare earth element separation agent with higher durability.

[0005] The inventors of the present invention considered that the low durability of previously reported adsorption separation agents was due to factors such as the dissolution of silica gel as the base material (Patent Document 1) and the use of ester monomers as reactive monomers to introduce diglycolamidic acid groups (Patent Document 2). As described later, adsorption separation tests of rare earth elements are often conducted under acidic conditions, raising concerns about the dissolution of the silica gel base material and hydrolysis of the ester moiety. As a result of diligent research, the inventors developed a highly durable adsorption separation agent for rare earth elements by producing porous reactive polymer particles made of reactive monomers such as styrene, divinylbenzene, and vinyl benzyl chloride (also known as chloromethylstyrene) using suspension polymerization, and immobilizing diglycolamidic acid groups on these particles as a support. Furthermore, in another form, polymerizable monomers having diglycolamidic acid groups were prepared, and polymers were produced by reversible addition-fragmentation-chain transfer (RAFT) polymerization, resulting in the development of a highly durable rare earth element separator. Based on these findings, the present invention was completed. In other words, the gist of the present invention is as follows.

[0006] [1] A compound comprising a support polymer and diglycolamide acid, wherein the diglycolamide acid is introduced into the support polymer via an alkyl-substituted benzene compound. [2] The above compound represented by the following formula (1).

[0007]

[0008] In the formula, P is a supporting polymer; R is a hydrogen atom, a C1-C3 alkyl group, or a C1-C3 alkoxy group, and m is an integer from 0 to 4; R １ R is an alkylene group having 1 to 3 carbon atoms; ２ R is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an acyl group having 1 to 2 carbon atoms; or a group represented by the following formula (i), ３ and R ４ Each of these is an independent alkylene group having 1 to 6 carbon atoms, and n is an integer from 0 to 5.

[0009]

[0010] [3] The above compound, wherein the supporting polymer is a polymer containing monomer units derived from a styrene monomer. [4] The above compound, wherein the styrene monomer is styrene and divinylbenzene. [5] The above compound, wherein the styrene monomer is divinylbenzene. [6] The above compound, wherein the supporting polymer is a polymer containing a structure derived from a RAFT polymerization chain transfer agent. [7] The above compound, wherein the RAFT polymerization chain transfer agent is 2-(dodecylthiocarbonothio)-2-methylpropanoic acid. [8] The above compound, wherein the supporting polymer is a polymer containing monomer units derived from a styrene monomer and a structure derived from a RAFT polymerization chain transfer agent. [9] The above compound, wherein the styrene monomer is styrene and divinylbenzene, and the RAFT polymerization chain transfer agent is 2-(dodecylthiocarbonothio)-2-methylpropanoic acid.

[10] A method for producing the above compound, comprising: (A) polymerizing an alkyl halogenated benzene compound and a monomer constituting a supporting polymer; (B) reacting the product of step (A) with an amino group introduction compound to convert it into an amination alkyl substituted benzene compound; and (C) reacting the product of step (B) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via an alkyl substituted benzene compound.

[11] A method for producing the above compound, comprising: (a) reacting an alkyl halogenated benzene compound with an amino group introduction compound to produce an amination alkyl substituted benzene compound; (b) reacting the product of step (a) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via an alkyl substituted benzene compound; and (c) reacting the product of step (b) with a RAFT polymerization chain transfer agent to polymerize it.

[12] A method for producing the above compound, comprising: (α) polymerizing an alkyl-substituted halogenated benzene compound and a monomer constituting a supporting polymer; (β) reacting the product of step (α) with an amino group introduction compound to convert it into an amination alkyl-substituted benzene compound; (γ) reacting the product of step (β) with a RAFT polymerization chain transfer agent to produce a compound in which a structure derived from the RAFT polymerization chain transfer agent is introduced via the alkyl-substituted benzene compound; (δ) reacting an alkyl-substituted halogenated benzene compound with an amino group introduction compound to produce an amination alkyl-substituted benzene compound; (ε) reacting the product of step (δ) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via the alkyl-substituted benzene compound; and (ζ) reacting the product of step (γ) with the product of step (ε) to polymerize.

[13] A separation agent for rare earth elements comprising the above compound.

[14] A method for recovering rare earth elements, comprising the step of contacting a solution containing rare earth elements with the separating agent to concentrate the rare earth elements with the separating agent.

[15] The above method, further comprising the step of desorbing the rare earth elements concentrated by the separating agent with an acid.

[16] The above method, wherein the solution containing rare earth elements is a mixed solution containing rare earth elements and a base metal, and rare earth elements are selectively separated from the mixed solution.

[0011] The present invention provides a compound having the ability to separate rare earth elements, a highly durable rare earth element separator utilizing the same compound, and a method for recovering rare earth elements.

[0012] Figure 1 shows the results of the acid resistance test of the adsorption separation agent in Test Example 1. A represents the amount of dysprosium (Dy) adsorbed by each adsorption separation agent, and B represents the retention rate of the adsorbed amount of dysprosium (Dy) after the acid resistance test. Figure 2 shows the results of the rare earth element adsorption test (pH dependent) of the adsorption separation agent in Test Example 2. Figure 3 shows the results of the rare earth element adsorption test (in the presence of a high concentration (excess amount) of base metal) of the adsorption separation agent in Test Example 3. Figure 4 shows the results of the precipitation separation test of rare earth elements of the separation agent in Test Example 4. Figure 5 shows the results of the rare earth element adsorption test (pH dependent) of the adsorption separation agent in Test Example 5. Figure 6 shows the results of the rare earth element adsorption test (in the presence of a high concentration of base metal) of the adsorption separation agent in Test Example 6. Figure 7 shows the results of the rare earth element adsorption test (pH dependent) of the adsorption separation agent in Test Example 7. Figure 8 shows the results of the adsorption test (pH-dependent) of rare earth elements using the adsorption separation agent in Test Example 8.

[0013] The present invention will be described below. However, the present invention is not limited to the following embodiments and can be freely modified within the scope of the present invention.

[0014] In this specification, when numerical ranges are expressed as "lower limit to upper limit," the upper limit may be "less than or equal to" or "less than," and the lower limit may be "greater than or equal to" or "greater than." In this specification, "rare earth elements" refers to the 17 elements that make up scandium (Sc) and yttrium (Y) of Group 3 (IIIA) of the Periodic Table, plus the 15 lanthanide elements. Furthermore, "heavy rare earth elements" refers to the lanthanide elements with atomic numbers 64 to 71 among the rare earth elements: gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0015] <Compound> One embodiment of the present invention relates to a compound (hereinafter sometimes referred to as "the compound of this embodiment") comprising a support polymer and diglycolamidic acid, wherein the diglycolamidic acid is introduced into the support polymer via an alkyl-substituted benzene compound. The compound has the ability to separate rare earth elements. The number of diglycolamidic acids introduced into the support polymer may be one or more. Alternatively, it may be about 0.1 to 1000 mmol per gram of support polymer.

[0016] In the compound of this embodiment, a supporting polymer is used instead of a silica gel substrate compared to previously reported adsorption separation agents, thereby suppressing the dissolution of the substrate. Furthermore, in one embodiment, an alkyl-substituted halogenated benzene is used as the reactive monomer for introducing the diglycolamidic acid group, instead of glycidyl methacrylate having an epoxy group, and it does not have a hydrolyzable ester group, thus suppressing degradation due to acid treatment.

[0017] While not particularly limited, a preferred embodiment of the compound of this embodiment is the compound represented by the following formula (1). Hereinafter, the compound of this embodiment may be described using the compound represented by formula (1) as an example, but the present invention is not limited to this embodiment.

[0018]

[0019] In the formula, P is a supporting polymer; R is a hydrogen atom, a C1-C3 alkyl group, or a C1-C3 alkoxy group, and m is an integer from 0 to 4; R １ R is an alkylene group having 1 to 3 carbon atoms; ２ R is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an acyl group having 1 to 2 carbon atoms; or a group represented by the following formula (i), ３ and R ４ Each of these is an independent alkylene group having 1 to 6 carbon atoms, and n is an integer from 0 to 5.

[0020]

[0021] The supporting polymer is not particularly limited as long as it can maintain the structure of the compound of this embodiment, and may be, for example, a polymer containing monomer units derived from a styrene monomer. The styrene monomer may be one or more combinations selected from styrene or styrene derivatives. The styrene derivative may be a crosslinkable monomer, a monofunctional monomer, or one or more combinations thereof, as described later. Examples of crosslinkable monomers include divinyl compounds such as divinylbenzene, divinylbiphenyl, divinylnaphthalene, and divinylphenanthrene. Monofunctional monomers include styrene monomers such as o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-t-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. In a preferred embodiment, the styrene monomers are styrene and divinylbenzene.

[0022] Furthermore, the supporting polymer may be a polymer containing a structure derived from a reversible addition-cleavage chain transfer (RAFT) polymerization chain transfer agent. The RAFT polymerization chain transfer agent may be one or a combination of two or more. As the RAFT polymerization chain transfer agent, polymerization initiators well known to those skilled in the art can be used. Examples of RAFT polymerization chain transfer agents include 2-cyanopropan-2-yl benzodithioate, 4-cyano-4-[(thiobenzoyl)sulfanyl]pentanoic acid, 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid (DDMAT), 4-cyano-4-[(thiobenzoyl)sulfanyl]pentanoic acid, 4-[(2-carboxyethylsulfanylthiocarbonyl)sulfanyl]-4-cyanopentanoic acid, 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid, and 4-cyano-4 Examples include -[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 2-cyano-2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propane, S,S-dibenzylic trithiocarbonate, 2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]methyl pentanoate, trithiocarbonate=bis[4-(allyloxycarbonyl)benzyl], 3,5-dimethylpyrazole-1-carbodichithioate cyanomethyl, etc. In a preferred embodiment, the RAFT polymerization chain transfer agent is 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid. The supporting polymer may also be a polymer containing monomer units derived from the styrene monomers described above and structures derived from the RAFT polymerization chain transfer agent described above.

[0023] In the compound of this embodiment, diglycolamic acid is introduced into the supporting polymer via an alkyl-substituted benzene compound. The benzene ring constituting the alkyl-substituted benzene compound may have a substituent R. The substituent is bonded to an arbitrary position on the benzene ring. The substituent of the alkyl-substituted benzene compound is not particularly limited, and examples thereof include linear or branched alkyl groups having 1 to 3 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, linear or branched alkoxy groups having 1 to 3 carbon atoms such as a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group, or a combination of one or more of these. Note that these substituents may further have another substituent. When the alkyl-substituted benzene compound has a substituent, the number m of the substituents is not particularly limited and is an integer of 0 to 4 (0, 1, 2, or 3, or 4). That is, m means the number of the above substituents (one or more may be present) excluding the hydrogen atom bonded to the benzene ring, the supporting polymer site, and the diglycolamic acid group. Also, the substitution position of the substituent on the benzene ring is not limited.

[0024] The alkylene group R constituting the alkyl-substituted benzene compound １ is a linear or branched alkylene group having 1 to 3 carbon atoms such as a methylene group, an ethylene group, an n-propylene group, and an isopropyl group. R １ is preferably a methylene group. The substitution position of the substituent R on the benzene ring １ is not limited, but the para position is preferable with respect to the bond to the supporting polymer.

[0025] In the above general formula (1), in one aspect, R ２ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an acyl group having 1 to 2 carbon atoms. The number of carbon atoms of the alkyl group is preferably 1 to 2, and more preferably 1. The number of carbon atoms of the acyl group is preferably 2.

[0026] R ２ Examples of the alkyl group in R include linear or branched alkyl groups having 1 to 3 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. R ２Examples of the acyl group in [it] include, for example, a formyl group, an acetyl group, and the like.

[0027] Alternatively, R ２ is a group represented by formula (i), and R ３ and R ４ are each independently an alkylene group having 1 to 6 carbon atoms. When a plurality of R ３ are present, they may be the same or different.

[0028] R ３ and R ４ Examples of the alkylene group in [it] include linear or branched alkylene groups having 1 to 6 carbon atoms such as a methylene group, an ethylene group, an n-propylene group, and an isopropylene group.

[0029] n is an integer from 0 to 5, and 0 or 1 is preferred.

[0030] As a preferred form of the compound of this embodiment, although not limited, a compound represented by formula (2) can be mentioned. The compound represented by formula (2) is, in formula (1), a support polymer in which P contains a monomer unit derived from styrene and divinylbenzene, or a support polymer containing a monomer unit derived from divinylbenzene; m is 0; R １ is a methylene group; R ２ is a group represented by formula (i), n is 0, and R ４ is an ethylene group.

[0031]

[0032] As another preferred form of the compound of this embodiment, although not limited, a compound represented by formula (3) can be mentioned. The compound represented by formula (3) is, in formula (1), a support polymer in which P contains a structure derived from a RAFT polymerization chain transfer agent, or a support polymer in which P contains a monomer unit derived from styrene and divinylbenzene and a structure derived from a RAFT polymerization chain transfer agent; m is 0; R １ is a methylene group; R ２ is a hydrogen atom.

[0033]

[0034] <Method for producing the compound> The compound of this embodiment can be produced by introducing diglycolamidic acid into the supporting polymer via an alkyl-substituted benzene compound, and can be produced using conventionally known organic synthesis methods.

[0035] In one embodiment, a method for producing the compound of this embodiment includes: (A) a step of polymerizing a halogenated alkyl-substituted benzene compound and a monomer constituting a supporting polymer; (B) a step of reacting the product of step (A) with an amino group introduction compound to convert the halogenated alkyl-substituted benzene compound into an amination alkyl-substituted benzene compound; and (C) a step of reacting the product of step (B) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via the alkyl-substituted benzene compound; and a method for producing the compound (hereinafter sometimes referred to as "the first method of production of this embodiment").

[0036] In this method, porous reactive polymer particles are produced by polymerizing alkyl halide-substituted benzene compounds and monomers constituting the supporting polymer. By immobilizing diglycolamidic acid groups on these particles, a compound can be produced that exhibits high selectivity for rare earth elements and excellent durability, making it suitable as a material for adsorption and separation agents for rare earth elements.

[0037] The following describes, more specifically, a method for producing the compound represented by formula (2) (where P is a supporting polymer containing monomer units derived from styrene and divinylbenzene) as an example, with reference to the scheme below.

[0038]

[0039] The upper steps in Scheme 1 are an example of step (A) of the first manufacturing method of this embodiment. A halogenated alkyl-substituted benzene compound (reactive monomer) such as vinyl benzyl chloride (VBC) (also known as chloromethylstyrene (CMS)) and monomers constituting a supporting polymer such as styrene and divinylbenzene are polymerized by suspension polymerization or the like. This produces a carrier having a halogenated alkyl-substituted benzene compound on the carrier.

[0040] The alkyl halide-substituted benzene compound is not particularly limited as long as it can copolymerize with the monomer constituting the supporting polymer and react with the amino group introduction compound to introduce an amino group; for example, it may be an alkyl halide-substituted styrene monomer. The styrene monomer may be one or more selected from styrene or styrene derivatives. The styrene derivative may be a crosslinkable monomer, a monofunctional monomer, or one or more of these. Examples of crosslinkable monomers include divinyl compounds such as divinylbenzene. Examples of monofunctional monomers include styrene monomers such as o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. In a preferred embodiment, the styrene monomer is styrene. The substituent alkyl halide may be a halogen atom in which some or all of the hydrogen atoms of a linear or branched C1-C3 alkyl group such as a methyl group, ethyl group, n-propyl group, or isopropyl group are substituted with halogen atoms such as chlorine, bromine, or iodine. Examples include chloromethyl, bromomethyl, iodomethyl, chloroethyl, bromoethyl, iodoethyl, chloro-n-propyl, bromo-n-propyl, iodo-n-propyl, chloroisopropyl, bromoisopropyl, iodoisopropyl, etc. Preferably, it is chloromethyl, chloroethyl, chloro-n-propyl, chloroisopropyl, etc., and more preferably chloromethyl. In one preferred embodiment, the alkyl halide-substituted benzene compound is vinyl benzyl chloride. The substitution position of the alkyl halide on the benzene ring is not limited, but the para position relative to the polymerizable functional group is preferred.

[0041] The content of alkyl-substituted benzene compounds (reactive monomers) in the total monomers constituting the supporting polymer is not particularly limited, but may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less. The above upper and lower limits can be combined arbitrarily.

[0042] The middle step of Scheme 1 is an example of step (B) of the first manufacturing method of this embodiment. The carrier, which is the product of step (A), is reacted with an amino group introduction compound such as ethylenediamine to produce an amination alkyl-substituted benzene compound. This produces a carrier in which an amino group has been introduced into the alkyl-substituted benzene compound.

[0043] The amino group introduction compound is not particularly limited as long as it can react with an alkyl-substituted benzene compound to introduce an amino group, and may be, for example, ammonia, an amine compound, or an amination reaction reagent. The amine compound is preferably a primary amine. The amino group introduction compound may be ammonia and one or more primary amines. The amine compound may be a monoamine or a polyamine such as a diamine. Furthermore, alkyl(poly)amines are preferred as amine compounds. The amino group introduction compound may be one or more combinations of two or more compounds. Examples of compounds for introducing amino groups include amines such as ammonia, methylamine, ethylamine, 1-propylamine, 2-propylamine, 1-butylamine, 2-butylamine, tert-butylamine, ethylenediamine, hexamethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methyl-1,2-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, bis(3-propylamino)amine, polyethyleneimine, etc., or azidating agents such as sodium azide and reducing agents such as lithium aluminum hydride, protective agents such as potassium phthalimide and deprotecting agents such as hydrazine, preferably ethylenediamine, sodium azide and lithium aluminum hydride, and more preferably ethylenediamine.

[0044] The lower steps of Scheme 1 are an example of step (C) of the first manufacturing method of this embodiment. The alkyl-substituted benzene compound, which is the product of step (B), is reacted with a carrier to which a primary or secondary amino group has been introduced, and diglycolic acid or diglycolic anhydride to introduce a diglycolamidic acid group. This produces the compound of this embodiment, in which diglycolamidic acid has been introduced to the carrier via the alkyl-substituted benzene compound.

[0045] When introducing diglycolamidic acid, which is the reaction site with rare earth elements, either diglycolic anhydride or diglycolic acid can be used. The reaction using diglycolic anhydride is simpler and less expensive, and therefore preferable.

[0046] In another embodiment, a method for producing the compound of this embodiment includes: (a) a step of reacting an alkyl-substituted halogenated benzene compound with an amino group introducing compound to produce an alkyl-substituted amino group benzene compound; (b) a step of reacting the product of step (a) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via an alkyl-substituted benzene compound; and (c) a step of reacting the product of step (b) with a RAFT polymerization chain transfer agent to polymerize the compound (hereinafter sometimes referred to as "the second method of production of this embodiment").

[0047] This method involves producing polymerizable monomers having diglycolamidic acid groups from alkyl-substituted benzene compounds, and then polymerizing these monomers using RAFT polymerization. This process yields compounds that exhibit high selectivity for rare earth elements and excellent durability, making them suitable as materials for rare earth element separators. In particular, these compounds can be used as precipitation separators to separate rare earth elements by precipitation.

[0048] The following describes, more specifically, a method for producing the compound represented by formula (3) (where P is a supporting polymer containing a structure derived from a RAFT polymerization chain transfer agent) as an example, with reference to the scheme below.

[0049]

[0050] The first step in the upper part of Scheme 2 is an example of step (a) of the second manufacturing method of this embodiment. A halogenated alkyl-substituted benzene compound (reactive monomer) such as VBC is reacted with sodium azide or the like to convert the halogenated alkyl-substituted benzene compound into an azidated alkyl-substituted benzene compound. Subsequently, the azidated alkyl-substituted benzene compound is reacted with a reducing agent such as lithium aluminum hydride to produce an amino-alkyl-substituted benzene compound such as vinylbenzylamine (VBA).

[0051] The alkyl-substituted benzene halide compound used in the second manufacturing method of this embodiment is the same as the alkyl-substituted benzene halide compound used in the first manufacturing method of this embodiment, and its preferred form is also the same.

[0052] The amino group introduction compound used in the second manufacturing method of this embodiment is the same as the amino group introduction compound used in the first manufacturing method of this embodiment. Preferred forms include sodium azide and lithium aluminum hydride.

[0053] The second step in the upper part of Scheme 2 is an example of step (b) of the second manufacturing method of this embodiment. The amination alkyl-substituted benzene compound, which is the product of step (a), is reacted with diglycolic acid or diglycolic anhydride to produce a polymerizable monomer in which a diglycolamidic acid such as vinylbenzyldiglycolamidic acid (VBDA) is introduced into the alkyl-substituted benzene compound.

[0054] The lower steps of Scheme 2 are an example of step (c) of the second manufacturing method of this embodiment. The diglycolamidic acid, which is the product of step (b), reacts with the polymerizable monomer introduced into the alkyl-substituted benzene compound and the RAFT polymerization chain transfer agent to polymerize. This results in PVBDA ｎ The compounds of this embodiment are produced by introducing diglycolamidic acid into a supporting polymer such as the above via an alkyl-substituted benzene compound.

[0055] RAFT polymerization can be carried out, for example, by heating the system in the presence of a polymerization initiator. Polymerization initiators well known to those skilled in the art can be used. The polymerization initiator may be one or a combination of two or more. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 2-(carbamoylazo)isobutyronitrile, and 2-phenylazo-4-methoxy- Examples of azo compounds include 2,4-dimethylvaleronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis(N,N'-dimethylisobutylamidine), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide)dihydrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), and peroxides such as benzoyl peroxide. In a preferred embodiment, the polymerization initiator is 2,2'-azobisisobutyronitrile.

[0056] The degree of polymerization of the polymerizable monomer is not particularly limited, but for example, it may be 3 or more, 5 or more, 10 or more, 15 or more, or less, 100 or less, 50 or less, 30 or less, or 20 or less. The above upper and lower limits can be arbitrarily controlled.

[0057] In another embodiment, a method for producing the compound of this embodiment includes: (α) a step of polymerizing an alkyl-substituted halogenated benzene compound and a monomer constituting a supporting polymer; (β) a step of reacting the product of step (α) with an amino group introduction compound to convert it into an amination alkyl-substituted benzene compound; (γ) a step of reacting the product of step (β) with a RAFT polymerization chain transfer agent to produce a compound in which a structure derived from the RAFT polymerization chain transfer agent is introduced via the alkyl-substituted benzene compound; (δ) a step of reacting an alkyl-substituted halogenated benzene compound with an amino group introduction compound to produce an amination alkyl-substituted benzene compound; (ε) a step of reacting the product of step (δ) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via the alkyl-substituted benzene compound; and (ζ) a step of reacting the product of step (γ) with the product of step (ε) to polymerize the compound (hereinafter sometimes referred to as "the third method of production of this embodiment").

[0058] In this method, porous reactive polymer particles are produced by polymerizing an alkyl-substituted benzene compound and a monomer constituting a supporting polymer. A RAFT polymerization chain transfer agent is reacted with these particles to introduce a structure derived from the RAFT polymerization chain transfer agent. Furthermore, the compound into which diglycolamide acid has been introduced via the alkyl-substituted benzene compound is subjected to RAFT polymerization to immobilize the diglycolamide acid group. This process produces a compound that can serve as a material for adsorption and separation agents of rare earth elements, exhibiting high selectivity for rare earth elements and excellent durability.

[0059] The following describes, more specifically, a method for producing the compound represented by formula (3) (where P is a supporting polymer containing monomer units derived from styrene and divinylbenzene, as well as a structure derived from a RAFT polymerization chain transfer agent) as an example, with reference to the scheme below.

[0060]

[0061] The upper step of Scheme 3 is the chlorination step of 2-(dodecylthiocarbonothio)-2-methylpropionic acid (DDMAT), which is a conventional technology.

[0062] P (St-DVB-VBC-EDA) in the middle of Scheme 3 is an example of an amination alkyl-substituted benzene compound obtained by steps (α) and (β) of the third manufacturing method of this embodiment. Step (α) in the third manufacturing method of this embodiment can be carried out in the same manner as step (A) in the first manufacturing method of this embodiment, and step (β) in the third manufacturing method of this embodiment can be carried out in the same manner as step (B) in the first manufacturing method of this embodiment, and the preferred form is also the same.

[0063] The middle step of Scheme 3 is an example of step (γ) of the third manufacturing method of this embodiment. The amination alkyl-substituted benzene compound, which is the product of step (β), is reacted with a RAFT polymerization chain transfer agent such as 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid to produce a polymerizable monomer in which a structure derived from the RAFT polymerization chain transfer agent, such as a thiocarbonylthio group, is introduced via the alkyl-substituted benzene compound.

[0064] VBDA in the lower step of Scheme 3 is an example of a compound in which diglycolamidic acid obtained by steps (δ) and (ε) of the third manufacturing method of this embodiment is introduced via an alkyl-substituted benzene compound. Step (δ) in the third manufacturing method of this embodiment can be carried out in the same manner as step (a) in the second manufacturing method of this embodiment, and step (ε) in the third manufacturing method of this embodiment can be carried out in the same manner as step (b) in the second manufacturing method of this embodiment, and the preferred form is also the same.

[0065] The lower steps of Scheme 3 are an example of step (ζ) of the third manufacturing method of this embodiment. A compound in which a structure derived from the RAFT polymerization chain transfer agent, which is the product of step (γ), is introduced via an alkyl-substituted benzene compound, is reacted with a compound in which diglycolamidic acid, which is the product of step (ε), is introduced via an alkyl-substituted benzene compound, and polymerized. This results in styrene, divinylbenzene, and PVBDA. ｎThe compound of this embodiment is produced by introducing diglycolamidic acid via an alkyl-substituted benzene compound into a supporting polymer containing the above.

[0066] The RAFT polymerization chain transfer agent used in the third manufacturing method of this embodiment is the same as the RAFT polymerization chain transfer agent used in the second manufacturing method of this embodiment, and its preferred form is also the same.

[0067] The RAFT polymerization method can also be carried out in the same manner as the RAFT polymerization method in the second manufacturing method of this embodiment, and the preferred form is also the same.

[0068] Furthermore, all matters described in the section on "<Compounds>" above apply to the description of the method for producing the compounds of this embodiment.

[0069] <Separating agent for rare earth elements> The compound of this embodiment has the ability to separate rare earth elements and can be used as a separating agent for rare earth elements. Utilizing this, another embodiment of the present invention relates to a separating agent for rare earth elements (hereinafter sometimes referred to as "the separating agent of this embodiment"), which includes the compound of this embodiment.

[0070] The content of the compound of this embodiment in the separation agent according to this embodiment is not particularly limited, but may be, for example, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, or 100% by mass. Other components in the rare earth element separation agent besides the compound of this embodiment are not particularly limited as long as they do not inhibit the extraction of rare earth metals, and examples include impurities and excipients, such as reagents used in the manufacturing process of the compound of this embodiment.

[0071] The separating agent in this embodiment can be made of any material or have any shape, as long as it has mechanical strength and acid resistance. Examples of the separating agent's shape include particulate matter, plates, rods, tubes, fibers, films, aqueous solutions, etc., and there are no particular restrictions on its shape.

[0072] Furthermore, the method for producing the rare earth element separation agent in this embodiment can be manufactured by using conventionally known methods for producing rare earth element adsorbents, such as molding, except when using the compound of this embodiment.

[0073] Furthermore, all matters described in the sections on <Compounds> and <Method for Producing Compounds> apply to the description of the separating agent in this embodiment.

[0074] <Method for recovering rare earth elements> Another embodiment of the present invention relates to a method for separating and recovering rare earth elements (hereinafter sometimes referred to as "the recovery method of this embodiment"), which includes the step of contacting a solution containing rare earth elements with the separating agent of the above embodiment to concentrate the rare earth elements with the rare earth element separating agent.

[0075] The method for bringing a solution containing rare earth elements into contact with a separation agent is not particularly limited as long as the solution containing rare earth element ions comes into contact with the separation agent. Examples include passing a solution containing rare earth element ions through a column equipped with a separation agent, adding a separation agent to a solution containing rare earth element ions, and mixing a solution containing rare earth element ions with a solution containing a separation agent.

[0076] In this embodiment, the solution containing rare earth elements is not particularly limited as long as the rare earth element ions are dissolved in an aqueous solution or a hydrophilic organic solvent such as a lower alcohol. However, it is preferable that the rare earth element ions contained in the solution are two or more ions selected from the group consisting of lanthanide ions with atomic numbers 57 to 71 and yttrium ions, and more preferably two or more ions selected from the group consisting of lanthanide (heavy rare earth) ions with atomic numbers 64 to 71. Furthermore, the rare earth element ions to be separated are not limited to a single element, and multiple rare earth element ions may be separated simultaneously. Note that the separation agent in this embodiment exhibits high selectivity for rare earth elements even in the presence of metal ions other than rare earth element ions (base metals), so the solution containing rare earth elements may also contain base metals.

[0077] (Concentration) The concentration of rare earth elements in a solution containing rare earth elements is not particularly limited, but for example, it may be 0.001 mmol / L or more, 0.01 mmol / L or more, 0.05 mmol / L or more, 0.1 mmol / L or more, 1 mmol / L or more, or 100 mmol / L or less, 50 mmol / L or less, 20 mmol / L or less, or 10 mmol / L or less. The above upper and lower limits can be combined arbitrarily.

[0078] The concentration of the separation agent of this embodiment in the solution during the rare earth element separation process is selected according to various conditions and the purpose of separation, but examples of specific concentration ranges are shown below. The lower limit of the concentration of the separation agent of this embodiment in the solution during the rare earth element separation process is a concentration where the compound of this embodiment is 0.01 mg / L or more, 0.1 mg / L or more, 0.5 mg / L or more, or 1 mg / L or more. The upper limit of the concentration of the separation agent of this embodiment in the solution during the rare earth element separation process is a concentration where the compound of this embodiment is 10,000 mg / L or less, 1,000 mg / L or less, 100 mg / L or less, or 10 mg / L or less. The above upper and lower limits can be combined arbitrarily.

[0079] (Temperature) The temperature at which this process is carried out is usually between 5°C and 80°C, and preferably between 10°C and 70°C.

[0080] (pH) The pH of the separation process is not particularly limited, but from the viewpoint of separation efficiency, it is preferable that the pH is between 0 and 5.5.

[0081] (Mutual Separation) Another embodiment of the present invention is a method for separating two or more rare earth elements from each other in a solution containing rare earth elements. According to this embodiment, since there are differences in the separation ability of each rare earth element, it can be applied to the mutual separation of rare earth elements.

[0082] (Desorption step) In this embodiment, the rare earth elements concentrated with the rare earth element separation agent obtained in the separation step can be desorbed with an acid. From the viewpoint of cost, hydrochloric acid, nitric acid, and sulfuric acid are preferred, and hydrochloric acid is more preferred. In this case, the acid concentration is preferably 0.001 mol / L or more and 4 mol / L or less, and more preferably 0.01 mol / L or more and 1 mol / L or less.

[0083] In addition, the method for recovering rare earth elements in this embodiment can be carried out using conventionally known methods for recovering rare earth elements, except for the use of the rare earth element separation agent in this embodiment.

[0084] Furthermore, the matters described in the sections on <Compounds>, ​​<Method for Producing Compounds>, ​​and <Separating Agents for Rare Earth Elements> all apply to the description of the recovery method in this embodiment.

[0085] The present invention will be specifically described below with reference to examples, but these are merely illustrative examples of the present invention, and the scope of the present invention is not limited thereto.

[0086] <Experiment 1> (Example of preparation 1) <Preparation of adsorbent separation agent>: P(St-DVB-VBC-EDA-DGA)

[0087]

[0088] [Synthesis of Adsorption Separation Agent Carrier Particles P (St-DVB-VBC)] 5.2 g (50 mmol) of styrene, 1.6 g (12 mmol) of divinylbenzene, 7.6 g (50 mmol) of vinylbenzyl chloride, and 0.25 g (1.5 mmol) of 2,2'-azobisisobutyronitrile were dissolved in a mixed solvent of 6 mL of heptane and 6 mL of toluene, and the mixture was stirred at room temperature to obtain an organic phase. As the aqueous phase, an aqueous solution of polyvinyl alcohol (0.25 wt%) prepared by dissolving 75 mg of polyvinyl alcohol in 30 mL of distilled water was used, and the mixture of the organic phase and aqueous phase was thoroughly stirred in a high-speed homogenizer to obtain a suspension. The suspension was reacted at 70°C for 6 hours, and then at 80°C for 2 hours, while stirring with a stirring blade. The stirring blade was rotated at a speed of 250 rpm. The obtained reaction product was filtered off, thoroughly washed sequentially with ethanol and water, and then dried under reduced pressure at 60°C. The dried reaction product was classified using a stainless steel sieve to obtain adsorbent separation agent carrier particles with a diameter of 425 to 710 μm.

[0089] [Synthesis of adsorbent P (St-DVB-VBC-EDA-DGA) by introducing diglycolamidic acid groups into adsorbent carrier particles] 18 g (0.30 mol) of ethylenediamine was mixed with 2 g of adsorbent carrier particles P (St-DVB-VBC) and reacted at 60°C for 24 hours. The resulting reaction product was filtered off, thoroughly washed sequentially with hydrochloric acid and water, and then dried under reduced pressure at 60°C to obtain P (St-DVB-VBC-EDA). 3.5 g (30 mmol) of diglycolic acid anhydride was added to 20 mL of dichloromethane and mixed, then 1.5 g of P (St-DVB-VBC-EDA) was added and reacted at 30°C for 72 hours. The resulting reaction product was thoroughly washed with water and then dried under reduced pressure at 60°C to obtain adsorbent P (St-DVB-VBC-EDA-DGA).

[0090] (Example 2) <Preparation of adsorbent separation agent>: P(St-DVB-VBC-EDA-DGA)acid

[0091]

[0092] [Acid Resistance Test] 0.5 g of the adsorbent separation agent P (St-DVB-VBC-EDA-DGA) obtained in Preparation Example 1 was placed in 20 mL of 1 mol / L hydrochloric acid and stirred at room temperature for 24 hours. After separating the adsorbent separation agent from the solution, the adsorbent separation agent was thoroughly washed with water and then dried under reduced pressure at 60°C to obtain adsorbent separation agent carrier particles P (St-DVB-VBC-EDA-DGA) acid.

[0093] (Example 5) <Preparation of adsorbent separation agent>: P(DVB-VBC-EDA-DGA)

[0094]

[0095] [Synthesis of Adsorption Separator Carrier Particles P (DVB-VBC)] 1.44 g (11 mmol) of divinylbenzene, 10.01 g (65 mmol) of vinylbenzyl chloride, and 0.11 g (1.5 mmol) of 2,2'-azobisisobutyronitrile were dissolved in a mixed solvent of 13.0 g of cyclohexanol and 7.00 g of heptane, and the mixture was stirred at room temperature to obtain an organic phase. As the aqueous phase, an aqueous solution of polyvinyl alcohol (0.30 wt%) prepared by dissolving 30 mg of polyvinyl alcohol in 100 mL of distilled water was used, and the mixture of the organic phase and aqueous phase was thoroughly stirred in a high-speed homogenizer to obtain a suspension. The suspension was reacted at 80°C for 6 hours while being stirred with a stirring blade. The stirring blade was rotated at a speed of 250 rpm. The obtained reaction product was filtered off, thoroughly washed sequentially with ethanol and water, and then dried under reduced pressure at 60°C. The dried reaction product was classified using a stainless steel sieve to obtain adsorbent separation agent carrier particles with a diameter of 425 to 710 μm.

[0096] [Synthesis of adsorbent P (DVB-VBC-EDA-DGA) by introducing diglycolamidic acid groups into adsorbent carrier particles] 22.2 g (0.37 mol) of ethylenediamine was added to 2.20 g of adsorbent carrier particles P (DVB-VBC) and reacted at 30°C for 9 days. The resulting reaction product was filtered off, thoroughly washed sequentially with hydrochloric acid and water, and then dried under reduced pressure at 60°C to obtain P (DVB-VBC-EDA). 5.59 g (48 mmol) of diglycolic acid anhydride was added to 35 mL of THF and mixed, then 2.12 g of P (DVB-VBC-EDA) was added and reacted at 50°C for 72 hours. The resulting reaction product was thoroughly washed with water, aqueous sodium hydroxide solution and hydrochloric acid, and then dried under reduced pressure at 60°C to obtain adsorbent P (DVB-VBC-EDA-DGA).

[0097] (Comparative Example 1) <Preparation of adsorption separation agent>: P(St-DVB-GMA-EDA-DGA)

[0098]

[0099] [Synthesis of Adsorption Separation Agent Carrier Particles P (St-DVB-GMA)] 5.2 g (50 mmol) of styrene, 1.6 g (12 mmol) of divinylbenzene, 7.1 g (50 mmol) of glycidyl methacrylate, and 0.25 g (1.5 mmol) of 2,2'-azobisisobutyronitrile were dissolved in a mixed solvent of 6 mL of heptane and 6 mL of toluene, and stirred at room temperature to obtain an organic phase. As the aqueous phase, an aqueous solution of polyvinyl alcohol (0.25 wt%) prepared by dissolving 75 mg of polyvinyl alcohol in 30 mL of distilled water was used, and the mixture of the organic phase and aqueous phase was thoroughly stirred in a high-speed homogenizer to obtain a suspension. The suspension was reacted at 70°C for 6 hours, and then at 80°C for 2 hours, while stirring with a stirring blade. The stirring blade was rotated at a speed of 250 rpm. The obtained reaction product was filtered off, thoroughly washed sequentially with ethanol and water, and then dried under reduced pressure at 60°C. The dried reaction product was classified using a stainless steel sieve to obtain adsorbent carrier particles P (St-DVB-GMA) with a diameter of 425 to 710 μm.

[0100] [Synthesis of adsorbent P (St-DVB-GMA-EDA-DGA) by introducing diglycolamidic acid groups into adsorbent carrier particles] 18 g (0.30 mol) of ethylenediamine was mixed with 2 g of adsorbent carrier particles P (St-DVB-GMA) and reacted at 60°C for 24 hours. The resulting reaction product was filtered off, thoroughly washed sequentially with hydrochloric acid and water, and then dried under reduced pressure at 60°C to obtain P (St-DVB-GMA-EDA). 3.5 g (30 mmol) of diglycolic acid anhydride was added to 20 mL of dichloromethane and mixed, then 1.5 g of P (St-DVB-GMA-EDA) was added and reacted at 30°C for 72 hours. The resulting reaction product was thoroughly washed with water and then dried under reduced pressure at 60°C to obtain adsorbent P (St-DVB-GMA-EDA-DGA).

[0101] (Comparative Example 2) <Preparation of adsorption separation agent>: P(St-DVB-GMA-EDA-DGA)acid

[0102]

[0103] [Acid Resistance Test] 0.5 g of the adsorption separation agent P (St-DVB-GMA-EDA-DGA) obtained in Comparative Example 1 was placed in 20 mL of 1 mol / L hydrochloric acid and stirred at room temperature for 24 hours. After separating the adsorption separation agent from the solution, the adsorption separation agent was thoroughly washed with water and then dried under reduced pressure at 60°C to obtain adsorption separation agent carrier particles P (St-DVB-GMA-EDA-DGA) acid.

[0104] (Test Example 1) <Acid Resistance of Each Adsorption Separator> A chloride salt of dysprosium (Dy) was dissolved in distilled water to a concentration of 5 mmol / L as a rare earth element, and the pH was adjusted to 2.5 with hydrochloric acid to prepare the adsorption test aqueous solution. 50 mg of the adsorption separator prepared in Preparation Examples 1 and 2 and Comparative Examples 1 and 2 was added to 5 mL of the adsorption test aqueous solution, and the adsorption test was performed at 25°C for 7 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"), and the amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 1. As shown in Figure 1, P(St-DVB-VBC-EDA-DGA) and P(St-DVB-VBC-EDA-DGA)acid, which use vinyl benzyl chloride as a monomer, showed no decrease in dysprosium (Dy) adsorption after the acid resistance test compared to P(St-DVB-GMA-EDA-DGA) and P(St-DVB-GMA-EDA-DGA)acid, which use glycidyl methacrylate as a monomer. Furthermore, the retention rate calculated by dividing the amount of dysprosium (Dy) adsorbed after the acid resistance test by the amount of dysprosium (Dy) adsorbed before the acid resistance test was higher, indicating superior durability under acid treatment.

[0105] (Test Example 2) <Adsorption Test of Rare Earth Elements>: As pH-dependent rare earth elements, dysprosium (Dy) chloride salt and neodymium (Nd) chloride salt, and as base metals, copper (Cu) and iron (Fe)(III) chloride salts were each dissolved in distilled water at a concentration of 1 mmol / L. The pH was then adjusted to 1-2 with hydrochloric acid to prepare the adsorption test aqueous solution. 50 mg of the adsorption separation agent prepared in Preparation Example 1 was added to 5 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 7 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"). The amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 2. From the results in Figure 2, it was shown that the adsorption separation agent of the present invention adsorbs dysprosium (Dy) at pH 1.5-1.7 and selectively adsorbs heavy rare earth elements.

[0106] (Test Example 3) <Adsorption Test of Rare Earth Elements>: Adsorption test in the presence of high concentration of base metal Chlorides of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb) were dissolved in distilled water at concentrations of 0.1 mmol / L or less, and chloride salts of copper (Cu) and iron (Fe)(III) were dissolved at concentrations of 10 mmol / L or less, respectively, as base metals. The pH was adjusted to 1 and 2 with hydrochloric acid to prepare the adsorption test aqueous solution. 50 mg of the adsorption separation agent prepared in Preparation Example 1 was added to 5 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 7 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"). The amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 3. From the results in Figure 3, it was revealed that the adsorption separation agent of the present invention adsorbs gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb) at pH 2, and selectively adsorbs dilute heavy rare earth elements even in the presence of high concentrations of base metal.

[0107] (Test Example 5) <Adsorption Test of Rare Earth Elements>: As pH-dependent rare earth elements, dysprosium (Dy) chloride salt and neodymium (Nd) chloride salt, and as base metals, copper (Cu) and iron (Fe)(III) chloride salts were each dissolved in distilled water at a concentration of 1 mmol / L. The pH was then adjusted to 0.5-2 with hydrochloric acid to prepare the adsorption test aqueous solution. 50 mg of the adsorption separation agent prepared in Preparation Example 5 was added to 5 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 7 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"). The amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 5. From the results in Figure 5, it was shown that the adsorption separation agent of the present invention selectively adsorbs dysprosium (Dy) at a pH of 0.5-1.

[0108] (Test Example 6) <Adsorption Test of Rare Earth Elements>: Adsorption test in the presence of high concentration of base metal. Chloride salts of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) were each dissolved in distilled water at a concentration of 0.1 mmol / L, and chloride salts of copper (Cu), iron (Fe)(III), aluminum (Al), manganese (Mn), cobalt (Co), nickel (Ni), and zinc (Zn) were each dissolved in distilled water at a concentration of 10 mmol / L, and the pH was adjusted to 1.5 with hydrochloric acid to prepare the adsorption test aqueous solution. 50 mg of the adsorption separation agent prepared in Preparation Example 5 was added to 5 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 7 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"), and the amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 6. From the results in Figure 6, it was revealed that the adsorption separation agent of the present invention adsorbs gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) at pH 1.5, and selectively adsorbs dilute heavy rare earth elements even in the presence of high concentrations of base metal.

[0109] <Experiment 2> (Preparation Example 3) <Synthesis of monomer having a diglycolamidic acid group (N-(4-vinylbenzyl)diglycolamidic acid (VBDA))>

[0110]

[0111] [Synthesis of Amine-Containing Monomer (4-Vinylbenzylamine (VBA))] 5.28 g (34.6 mmol) of 4-vinylbenzyl chloride (VBC), 2.81 g (43.2 mmol) of sodium azide, and 0.12 g (0.32 mmol) of tetrabutylammonium iodide were dissolved in 400 mL of dimethylformamide and stirred at room temperature for 4 hours. 200 mL of diethyl ether and 200 mL of distilled water were added to the resulting reaction solution, and the mixture was transferred to a separatory funnel for extraction. The aqueous phase was discarded, and 200 mL of distilled water was added to the remaining organic phase for further extraction. The aqueous phase was discarded again, and 200 mL of distilled water was added to the remaining organic phase for further extraction. The organic phase was separated, dried over magnesium sulfate, and the magnesium sulfate was filtered off. The resulting solution was concentrated. 50 mL of anhydrous diethyl ether was added to the concentrate, and while stirring in an ice bath, approximately 0.13 g of lithium aluminum hydride suspended in approximately 5 mL of anhydrous diethyl ether was slowly added dropwise. This procedure was repeated 10 times to add approximately 1.3 g (approximately 36 mmol) of lithium aluminum hydride, and the reaction was carried out in an ice bath for 2 hours. To deactivate the unreacted lithium aluminum hydride, 1.4 mL of water, 1.4 mL of 0.1 mol / L sodium hydroxide aqueous solution, and 4.2 mL of water were added dropwise in sequence, and the mixture was stirred at room temperature for 1 hour after each addition. The suspension after the reaction was filtered using Celite, and the Celite and reaction vessel were washed with dichloromethane and diethyl ether. The filtrate was concentrated, 50 mL of dichloromethane and 50 mL of saturated saline solution were added, and the mixture was transferred to a separatory funnel for extraction. The organic phase was separated, dried over magnesium sulfate, and the magnesium sulfate was filtered off. The resulting solution was concentrated to obtain 4-vinylbenzylamine.

[0112] [Synthesis of monomer having a diglycolamidic acid group (VBDA)] 3.61 g (31.1 mmol) of diglycolic anhydride was added to 50 mL of anhydrous tetrahydrofuran and completely dissolved. 2.05 g (15.4 mmol) of 4-vinylbenzylamine was dissolved in 50 mL of anhydrous tetrahydrofuran and slowly added dropwise to the above solution using a dropping funnel under an ice bath. After the addition was complete, the mixed solution was stirred at room temperature for 18 hours. The reaction solution was concentrated to obtain a crude product in the form of a white solid. The crude product was washed with 100 mL of dichloromethane and 100 mL of diethyl ether and filtered to obtain monomer VBDA having a diglycolamidic acid group.

[0113] (Example 4) <Linear polymer having diglycolamidic acid group in the side chain (PVBDA ｎ ) Synthesis >

[0114]

[0115] [PVBDA with a degree of polymerization n = 8 to 9] ｎ [Synthesis] 0.40 g (1.6 mmol) of VBDA, 0.034 g (0.094 mmol) of 2-(dodecylthiocarbonothio)-2-methylpropionic acid (DDMAT), and 0.0050 g (0.030 mmol) of 2,2'-azobisisobutyronitrile (AIBN) were completely dissolved in 3.6 mL of 1,4-dioxane. After three freeze-degassing cycles, the mixture was reacted at 80°C for 21 hours. The resulting solution was added dropwise to 100 mL of diethyl ether, and the precipitated material was separated by decantation. The mixture was dried under reduced pressure at 25°C to obtain a solid. Proton nuclear magnetic resonance (MRN) measurements revealed that the degree of polymerization n of the obtained solid was 8-9.

[0116] [PVBDA with a degree of polymerization n = 12 to 13] ｎ [Synthesis] The reaction and purification were carried out under the same conditions and procedures as above, except that the amount of 2-(dodecylthiocarbonothio)-2-methylpropionic acid was changed to 0.025 g (0.070 mmol), to obtain solid PVBDA. ｎ (n=12-13) was obtained.

[0117] [PVBDA with a degree of polymerization n = 15 to 17] ｎ[Synthesis] The reaction and purification were carried out under the same conditions and procedures as above, except that the amount of 2-(dodecylthiocarbonothio)-2-methylpropionic acid was changed to 0.017 g (0.047 mmol), to obtain solid PVBDA. ｎ (n = 15 to 17) was obtained.

[0118] (Test Example 4) <PVBDA ｎ Precipitation and separation test of rare earth elements using PVBDA > PVBDA ｎ (n=8-9) were dissolved in dimethyl sulfoxide to prepare a 1 g / L polymer solution. 0.5 mL of the polymer solution was mixed with 0.5 mL of an aqueous hydrochloric acid solution (pH 1.95) containing 0.1 mmol / L each of nine rare earth elements (lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), erbium (Er), ytterbium (Yb)) and two base metals (copper (Cu), iron (Fe) (III)). The mixture was shaken at 25°C and 350 rpm for 24 hours to perform a separation test. After shaking, centrifugation was performed at 25°C and 10000 rpm for 15 min. After centrifugation, 0.5 mL of the supernatant of the solution was taken and diluted 10-fold with distilled water. The diluted solution was filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"). The recovery rate of metal ions was calculated from the mass balance. Figure 4 shows PVBDA ｎ It was shown to selectively concentrate gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb), and is useful as a separator for heavy rare earth elements.

[0119] From these results, it was found that a rare earth element separator utilizing a compound in which diglycolamidic acid is introduced into the supporting polymer via an alkyl-substituted benzene compound is capable of selectively recovering rare earth elements, especially heavy rare earth elements, and is a rare earth element separator with excellent durability.

[0120] <Experiment 3> (Example 6) <Linear polymer having diglycolamidic acid group in the side chain (PVBDA) ｎ Synthesis of an adsorbent separation agent having ) in its graft chain >

[0121]

[0122] In the above formula, P represents a supporting polymer containing monomer units derived from styrene and divinylbenzene.

[0123] 1.0 g (2.7 mmol) of 2-(dodecylthiocarbonothio)-2-methylpropionic acid (DDMAT) was dissolved in 50 mL of anhydrous dichloromethane. 1.0 g (8.1 mmol) of oxalyl chloride was added dropwise using a dropping funnel while stirring in an ice bath, and the mixture was stirred for 3 hours at room temperature. 200 mg of P(St-DVB-VBC-EDA) prepared in Preparation Example 1 was added to the resulting reaction solution, and the mixture was stirred at room temperature for 18 hours. The resulting reaction product was filtered, thoroughly washed sequentially with THF and water, and then dried under reduced pressure at 60°C to obtain P(St-DVB-VBC-EDA-DDMAT). In Preparation Example 3, 1.2 g (4.8 mmol) of VBDA (N-(4-vinylbenzyl)diglycolamidic acid) and 0.04 g (0.23 mmol) of 2,2'-azobisisobutyronitrile (AIBN) were completely dissolved in 108 mL of 1,4-dioxane. 200 mg of P (St-DVB-VBC-EDA-DDMAT) was added, and the mixture was stirred at 75°C for 72 hours. The resulting reaction product was filtered, thoroughly washed sequentially with DMSO and water, and then dried under reduced pressure at 60°C to obtain adsorbent carrier particles P (St-DVB-VBC-EDA-DDMAT-VBDA). The supernatant after the reaction was added dropwise to 200 mL of diethyl ether, and the precipitated material was separated by decantation. The solid was dried under reduced pressure at 25°C to obtain a solid. Proton nuclear magnetic resonance (MRN) measurements revealed that the degree of polymerization n of the obtained solid was 13. This corresponds to the degree of polymerization of the polymer chains on the surface of P(St-DVB-VBC-EDA-DDMAT-VBDA).

[0124] (Test Example 7) <Adsorption Test of Rare Earth Elements>: As pH-dependent rare earth elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb), and as base metals, the chloride salts of copper (Cu) and iron (Fe) (III) were dissolved in distilled water at a concentration of 0.1 mmol / L, and the pH was adjusted to 2 with hydrochloric acid to prepare the adsorption test aqueous solution. 30 mg of the adsorption separation agent prepared in Preparation Example 6 was added to 3 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 5 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"), and the amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 7. The results shown in Figure 7 demonstrate that the adsorption separation agent of the present invention adsorbs gadolinium (Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb) at pH 2, clearly demonstrating selective adsorption of heavy rare earth elements.

[0125] (Test Example 8) <Adsorption Test of Rare Earth Elements>: As pH-dependent rare earth elements, dysprosium (Dy) chloride salt and neodymium (Nd) chloride salt, and as base metals, copper (Cu) and iron (Fe)(III) chloride salts were dissolved in distilled water at a concentration of 0.10 mmol / L each. The pH was then adjusted to 1-2 with hydrochloric acid to prepare the adsorption test aqueous solution. 30 mg of the adsorption separation agent prepared in Preparation Example 6 was added to 3 mL of the adsorption test aqueous solution, and the adsorption test was carried out at 25°C for 5 days while shaking. After the adsorption test, the solution was collected, filtered through a 0.20 μm membrane filter, and the metal ion concentration in the aqueous solution was measured using an ICP emission spectrometer (Shimadzu Corporation "ICPE-9000"). The amount of adsorbed metal ions was calculated from the mass balance. The results are shown in Figure 8. The results shown in Figure 8 demonstrate that the adsorption separation agent of the present invention adsorbs dysprosium (Dy) at pH 1.5 to 2 and selectively adsorbs heavy rare earth elements.

[0126] According to the present invention, rare earth elements, especially heavy rare earth elements, can be selectively, simply, and inexpensively recovered from a solution consisting of rare earth elements and base metal elements. Furthermore, because it offers excellent durability and reduced running costs, it can further develop the smelting and recycling industry for rare earth elements, especially heavy rare earth elements.

Claims

1. A compound comprising a support polymer and diglycolamide acid, wherein the diglycolamide acid is introduced into the support polymer via an alkyl-substituted benzene compound.

2. The compound according to claim 1, represented by the following formula (1). In the formula, P is a supporting polymer; R is a hydrogen atom, a C1-C3 alkyl group, or a C1-C3 alkoxy group, and m is an integer from 0 to 4; R １ R is an alkylene group having 1 to 3 carbon atoms; ２ R is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an acyl group having 1 to 2 carbon atoms; or a group represented by the following formula (i), ３ and R ４ Each of these is an independent alkylene group having 1 to 6 carbon atoms, and n is an integer from 0 to 5.

3. The compound according to claim 1, wherein the supporting polymer is a polymer containing monomer units derived from styrene monomers.

4. The compound according to claim 3, wherein the styrene monomer is styrene and divinylbenzene.

5. The compound according to claim 3, wherein the styrene monomer is divinylbenzene.

6. The compound according to claim 1, wherein the supporting polymer is a polymer containing a structure derived from a RAFT polymerization chain transfer agent.

7. The compound according to claim 6, wherein the RAFT polymerization chain transfer agent is 2-(dodecylthiocarbonothiolthio)-2-methylpropanoic acid.

8. The compound according to claim 1, wherein the supporting polymer is a polymer comprising monomer units derived from styrene monomers and structures derived from a RAFT polymerization chain transfer agent.

9. The compound according to claim 8, wherein the styrene monomer is styrene and divinylbenzene, and the RAFT polymerization chain transfer agent is 2-(dodecylthiocarbonothio)-2-methylpropanoic acid.

10. A method for producing the compound according to claim 1, comprising: (A) polymerizing a halogenated alkyl-substituted benzene compound and a monomer constituting a supporting polymer; (B) reacting the product of step (A) with an amino group introduction compound to convert it into an amination alkyl-substituted benzene compound; and (C) reacting the product of step (B) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via an alkyl-substituted benzene compound.

11. A method for producing the compound according to claim 1, comprising: (a) reacting an alkyl-substituted halogenated benzene compound with an amino group introduction compound to produce an alkyl-substituted amino acid benzene compound; (b) reacting the product of step (a) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via an alkyl-substituted benzene compound; and (c) reacting the product of step (b) with a RAFT polymerization chain transfer agent to polymerize it.

12. A method for producing the compound according to claim 1, comprising: (α) polymerizing a halogenated alkyl-substituted benzene compound and a monomer constituting a supporting polymer; (β) reacting the product of step (α) with an amino group introduction compound to convert it into an amination alkyl-substituted benzene compound; (γ) reacting the product of step (β) with a RAFT polymerization chain transfer agent to produce a compound in which a structure derived from the RAFT polymerization chain transfer agent is introduced via the alkyl-substituted benzene compound; (δ) reacting a halogenated alkyl-substituted benzene compound with an amino group introduction compound to produce an amination alkyl-substituted benzene compound; (ε) reacting the product of step (δ) with diglycolic acid or diglycolic anhydride to produce a compound in which diglycolamidic acid is introduced via the alkyl-substituted benzene compound; and (ζ) reacting the product of step (γ) with the product of step (ε) to polymerize.

13. A separation agent for rare earth elements comprising the compound described in any one of claims 1 to 9.

14. A method for recovering rare earth elements, comprising the step of contacting a solution containing rare earth elements with the separating agent described in claim 13 to concentrate the rare earth elements with the separating agent.

15. The method according to claim 14, further comprising the step of desorbing the rare earth elements concentrated by the separating agent with an acid.

16. The method according to claim 14, wherein the solution containing the rare earth element is a mixed solution containing the rare earth element and a base metal, and the rare earth element is selectively separated from the mixed solution.

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