Cationic exchange resin, method for preparing same, ion exchange membrane for seperating alkali metal species, and electrodialysis device for lithium extraction

Abstract

A cation exchange resin according to the present invention comprises: a first repeating unit represented by chemical formula 1; and a second repeating unit represented by chemical formula 2. In chemical formula 1, X and X' are each independently hydrogen or an alkali metal species (E), and A1 is represented by chemical formula 3 or chemical formula 4. In chemical formula 2, A2 is represented by chemical formula 3 or chemical formula 4. In chemical formula 3, Z1 is –S-, -O-, -C(O)-, or -C(R1R2)-, and R1 and R2 are each independently a hydrogen atom, an alkyl group of C1 to C2, a halogen, or a halogen-substituted alkyl group of C1 to C2.

Description

Cation exchange resin, method for producing same, ion exchange membrane for separation of alkali metal species and electrodialysis device for lithium extraction

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0127404, filed September 22, 2023, and Korean Patent Application No. 10-2023-0188239, filed December 21, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a cation exchange resin and a method for producing the same, and to an ion exchange membrane for separating alkali metal species and an electrodialysis device for extracting lithium, including the cation exchange resin.

[0003] Electrodialysis is a device that uses direct current as a driving force to separate and concentrate ionic substances in a solution using cation-exchange membranes and anion-exchange membranes. Traditionally, electrodialysis has been used for seawater desalination, desalination, removal of heavy metals from soil, and treatment of various industrial wastes. However, it has recently gained attention as an environmentally friendly method for extracting lithium, a key mineral material for secondary batteries.

[0004] Ion-exchange membranes, a key material used in electrodialysis for lithium extraction, are particularly cation-exchange membranes, which selectively pass lithium ions through and concentrate them in the form of lithium hydroxide. Currently commercially available cation-exchange membranes are either perfluorosulfonic acid (PFSA) ion-exchange resins or cross-linked polystyrene resins containing sulfonated functional groups, either alone or impregnated onto a polymer support.

[0005] However, in the case of fluorine-based ion exchange resins, despite their high ion conductivity and excellent chemical stability, they are very expensive, have somewhat poor stability at high temperatures, and are subject to stricter regulations regarding their use due to environmental pollution.

[0006] In addition, since sulfonated polystyrene resins are prone to breaking during membrane drying, they must be used in the form of composite membranes, but processing is not easy, and their mechanical and chemical stability is significantly lower than that of fluorinated cation exchange resins.

[0007] Therefore, there is a need to develop a cation exchange resin for lithium extraction that is more economical than fluorine-based cation exchange resins and has improved mechanical and chemical stability.

[0008] The present invention is intended to solve the above problems, and to provide a cation exchange resin and a method for producing the same, which have high ionic conductivity and excellent chemical stability and can be produced at a lower cost than conventional fluorine-based cation exchange resins.

[0009] In addition, the present invention aims to provide an ion exchange membrane for separating alkali metal species and an electrodialysis device for extracting lithium, manufactured using the cation exchange resin as described above.

[0010] In one aspect, the present invention provides a cation exchange resin comprising a first repeating unit represented by the following chemical formula 1; and a second repeating unit represented by the following chemical formula 2.

[0011] [Chemical Formula 1]

[0012]

[0013] (In the above chemical formula 1,

[0014] X and X' are each independently hydrogen or an alkali metal species (E), and A 1 is represented by the following chemical formula 3 or the following chemical formula 4.)

[0015] [Chemical Formula 2]

[0016]

[0017] (In the above chemical formula 2,

[0018] A 2is represented by the following chemical formula 3 or the following chemical formula 4.)

[0019] [Chemical Formula 3]

[0020]

[0021] (In the above chemical formula 3,

[0022] Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and,

[0023] R 1 and R 2 are each independently hydrogen, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group.)

[0024] [Chemical Formula 4]

[0025]

[0026]

[0027] In another aspect, the present invention provides a cation exchange resin composition comprising the cation exchange resin and an ion exchange membrane for separating alkali metal species (M) obtained by forming a molded film of the resin composition.

[0028]

[0029] In another aspect, the present invention provides an ion exchange membrane for separating alkali metal species (M) comprising the cation exchange resin.

[0030]

[0031] In another aspect, the present invention provides an electrodialysis device for lithium extraction comprising an exchange membrane for separating the alkali metal species (M).

[0032]

[0033] In another aspect, the present invention provides a method for producing a cation exchange resin, comprising a step of polymerizing a reaction mixture comprising a first monomer represented by the following chemical formula 7, a second monomer represented by the following chemical formula 8, a third monomer represented by the following chemical formula 9 or the following chemical formula 10, and a polymerization solvent.

[0034] [Chemical Formula 7]

[0035]

[0036] (In the above chemical formula 7,

[0037] L 1 and L 2 are leaving groups removed during the above polymerization reaction, and each is independently a halogen element.)

[0038] [Chemical Formula 8]

[0039]

[0040] (In the above chemical formula 8,

[0041] X and X' are each independently hydrogen or an alkali metal species (E) other than the alkali metal species (M),

[0042] L 3 and L 4 are leaving groups removed during the above polymerization reaction, and each is independently a halogen element.)

[0043] [Chemical Formula 9]

[0044]

[0045] (In the above chemical formula 9,

[0046] Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and,

[0047] R 1 and R 2 are each independently hydrogen, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group,

[0048] L 5 and L 6 are leaving groups removed during the polymerization reaction, and each independently represents a cation or hydrogen atom of an alkali metal species (E).

[0049] [Chemical Formula 10]

[0050]

[0051] (In the above chemical formula 10,

[0052] L 7 and L 8 are leaving groups removed during the polymerization reaction, and each independently represents a cation or hydrogen atom of an alkali metal species (E).

[0053]

[0054] The cation exchange resin according to the present invention comprises repeating units having a structure in which benzene groups and / or sulfonated benzene groups are bonded via thioether bonds to a phenylsulfone structure substituted with a sulfonic acid group having excellent ion exchange performance. As in the cation exchange resin of the present invention, when benzene groups are bonded via thioether groups, the bonding force is stronger than when benzene groups are bonded via ether groups, and thus higher chemical stability can be achieved compared to existing commercially available sulfonated polystyrene.

[0055] In addition, the cation exchange resin according to the present invention can be synthesized using relatively inexpensive monomers and has an easy polymerization process, so it can be manufactured more economically than existing commercially available fluorine-based ion exchange resins.

[0056] In addition, the ion exchange membrane for separation of alkali metal species (M) manufactured using the cation exchange resin according to the present invention has excellent swelling characteristics when immersed in water, and has excellent alkali resistance, so that it can be stably operated in a wide pH range.

[0057] In addition, when manufacturing an ion exchange membrane for separating alkali metal species (M) using the cation exchange resin according to the present invention, a porous polyolefin or inorganic fiber having excellent dimensional stability and low price can be used as a support, so that an ion exchange membrane having excellent mechanical durability while being inexpensive can be manufactured.

[0058] Figure 1 is a flow chart showing a method for manufacturing a cation exchange resin according to the present invention.

[0059] Figure 2 is a drawing illustrating an electrodialysis device for lithium extraction according to the present invention.

[0060] Hereinafter, the present invention will be described in more detail.

[0061]

[0062] cation exchange resin

[0063] First, the cation exchange resin according to the present invention will be described.

[0064] The cation exchange resin according to the present invention comprises a first repeating unit represented by the following chemical formula 1, and a second repeating unit represented by the following chemical formula 2.

[0065] [Chemical Formula 1]

[0066]

[0067] In the above chemical formula 1,

[0068] The above X and X' may each independently be hydrogen or an alkali metal species (E). At this time, the alkali metal species (E) may be, for example, Li, Na, or K, and preferably, Na or K.

[0069] [Chemical Formula 2]

[0070]

[0071] In the above chemical formula 2, A 2 It may be represented by the following chemical formula 3 or the following chemical formula 4.

[0072] [Chemical Formula 3]

[0073]

[0074] In the above chemical formula 3, Z 1 -S-, -O-, -C(=O)- or -C(R 1 R 2 )-and R 1 and R 2 are each independently hydrogen, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group. Preferably, the Z 1 can be -S- or -O-.

[0075] [Chemical Formula 4]

[0076]

[0077] Meanwhile, the A in the chemical formula 1 1 And the above A in the above chemical formula 2 2 They may be identical or different, but it is preferable that they be identical in terms of ease of synthesis and manufacturing cost.

[0078] Specifically, the A in the above chemical formula 1 1 And the above A in the above chemical formula 2 2 It may be represented by the following chemical formula 3 or may be represented by the following chemical formula 4.

[0079]

[0080] The first repeating unit includes a sulfonic acid group substituted on a phenyl group, and the sulfonic acid group acts as a cation exchanger to realize high ion exchange performance. In addition, the first and second repeating units have a structure in which benzenes are bonded via a thioether group with a higher bonding strength than an ether group, and therefore have excellent chemical stability, such as pH stability. Therefore, the cation exchange resin according to the present invention including the first and second repeating units has high ion exchange performance and excellent chemical stability.

[0081]

[0082] Specifically, the first repeating unit may be represented by the following chemical formula 1A.

[0083] [Chemical Formula 1A]

[0084]

[0085] In the above chemical formula 1A, X, X', and A 1 are each the same as described in the above chemical formula 1. When the sulfonic acid group is substituted at the same position as the above chemical formula 1A, synthesis is easy and the ion exchange performance is better.

[0086]

[0087] Meanwhile, the cation exchange resin according to the present invention may include the first repeating unit: the second repeating unit in a molar ratio of 30:70 to 70:30, preferably 30:70 to 60:40, more preferably 30:70 to 50:50. When the first repeating unit and the second repeating unit satisfy the molar ratio, the ion exchange performance, chemical stability, and swelling characteristics are all excellent. When the molar ratio of the first repeating unit is smaller than the above range, the content of sulfonic acid groups acting as cation exchangers may decrease, resulting in a decrease in ion exchange capacity, and when it exceeds the above range, water absorbency may increase, resulting in a decrease in swelling characteristics.

[0088]

[0089] More specifically, the cation exchange resin according to the present invention may include a repeating unit represented by the following chemical formula 5 or a repeating unit represented by the following chemical formula 6.

[0090] [Chemical Formula 5]

[0091]

[0092] In the above chemical formula 5, X and X' are the same as defined in the above chemical formula 1, and Z 1 , R 1and R 2 is the same as defined in the above chemical formula 3.

[0093] Meanwhile, the above m1 is a positive number greater than 0 and less than or equal to 1, and preferably may be a positive number of 0.3 to 0.7, a positive number of 0.3 to 0.6, or a positive number of 0.3 to 0.5. When m1 satisfies the above range, ion exchange performance, chemical stability, and swelling characteristics are all excellent. If m1 is too small, the content of sulfonic acid groups acting as cation exchangers may decrease, which may lower the ion exchange capacity, and if m1 is too large, water absorbency may increase, which may lower the swelling characteristics.

[0094] The above n1 may be an integer from 30 to 1,000, preferably an integer from 30 to 800. When n1 satisfies the above range, the weight average molecular weight of the cation exchange resin can be appropriately controlled. If n1 is too small, the ion exchange capacity and mechanical properties may be reduced, and if n1 is too large, the viscosity of the resin composition may increase, making it difficult to manufacture the ion exchange membrane.

[0095] [Chemical Formula 6]

[0096]

[0097] In the above chemical formula 6, X and X' are the same as defined in the above chemical formula 1, and Z 1 , R 1 and R 2 is the same as defined in the above chemical formula 3.

[0098] Meanwhile, the above m2 is a positive number greater than 0 and less than or equal to 1, and preferably may be a positive number of 0.3 to 0.7, a positive number of 0.3 to 0.6, or a positive number of 0.3 to 0.5. When m2 satisfies the above range, the ion exchange performance, chemical stability, and swelling characteristics are all excellent. If m2 is too small, the content of sulfonic acid groups acting as cation exchangers may decrease, which may lower the ion exchange capacity, and if it is too large, water absorbency may increase, which may lower the swelling characteristics.

[0099] The above n2 may be an integer from 50 to 1,000, preferably an integer from 30 to 800. When n2 satisfies the above range, the weight average molecular weight of the cation exchange resin can be appropriately controlled. If n2 is too small, the ion exchange capacity and mechanical properties may be reduced, and if n2 is too large, the viscosity of the resin composition may increase, making it difficult to manufacture the ion exchange membrane.

[0100]

[0101] In addition, the cation exchange resin according to the present invention may have a weight average molecular weight of 50,000 g / mol to 500,000 g / mol, preferably 50,000 g / mol to 400,000 g / mol, and more preferably 100,000 g / mol to 400,000 g / mol. When the weight average molecular weight of the cation exchange resin satisfies the above range, the ion exchange membrane is easily manufactured, and the ion exchange membrane exhibits excellent mechanical strength.

[0102]

[0103] Method for manufacturing cation exchange resin

[0104] Next, a method for manufacturing a cation exchange resin according to the present invention will be described.

[0105] A cation exchange resin according to the present invention can be manufactured by including a step of polymerizing a reaction mixture comprising a first monomer represented by the following chemical formula 7, a second monomer represented by the following chemical formula 8, a third monomer represented by the following chemical formula 9 or the following chemical formula 10, and a polymerization solvent.

[0106]

[0107] Figure 1 illustrates a method for manufacturing a cation exchange resin according to the present invention.

[0108] As illustrated in FIG. 1, the method for manufacturing a cation exchange resin according to the present invention includes a step (S1) of forming a reaction mixture by adding a polymerization solvent to a mixture of a first monomer, a second monomer, and a third monomer, and a step (S2) of polymerizing the reaction mixture to synthesize a cation exchange resin.

[0109] In addition, the method for manufacturing a cation exchange resin according to the present invention may further include, if necessary, a step (S3) of separating the synthesized cation exchange resin, washing it with water, and drying it to manufacture a solid cation exchange resin, and a step (S4) of redissolving the solid cation exchange resin to form a liquid cation exchange resin composition.

[0110]

[0111] Hereinafter, a method for manufacturing a cation exchange resin according to the present invention will be described in more detail.

[0112] First, a polymerization solvent is added to a mixture of a first monomer, a second monomer, and a third monomer to form a reaction mixture (step S1).

[0113] At this time, the first monomer constitutes the second repeating unit in the cation exchange resin according to the present invention and is a compound represented by the following chemical formula 7 for imparting mechanical and chemical stability to the cation exchange resin.

[0114] [Chemical Formula 7]

[0115]

[0116] In the above chemical formula 7, L 1 and L 2 is a leaving group removed during the polymerization reaction, and each may independently be a halogen element such as F, Cl, Br, I, etc. or a hydrogen atom, and preferably a halogen element.

[0117] Specifically, the first monomer may be diphenyl sulfone, 4,4'-dihalogendiphenyl sulfone, or a combination thereof, and among these, 4,4'-dichlorodiphenyl sulfone (DCDPS) is particularly preferred.

[0118] As the first monomer, a compound having a purity of 99% or higher may preferably be used. This is because, if a compound having a purity of less than 99% is used as the first monomer, side reactions may occur due to impurities.

[0119] Meanwhile, the first monomer may be included in an amount of 10 to 40 parts by weight, preferably 20 to 35 parts by weight, and more preferably 22 to 35 parts by weight, based on 100 parts by weight of the total weight of the first to third monomers.

[0120] When the content of the first monomer among the total monomers satisfies the above range, the ratio of the second repeating unit in the cation exchange resin is appropriately formed, thereby ensuring excellent mechanical properties and chemical stability.

[0121] Next, the second monomer is a compound represented by the following chemical formula 8, which constitutes the first repeating unit in the cation exchange resin according to the present invention and imparts cation exchange performance to the cation exchange resin.

[0122] [Chemical Formula 8]

[0123]

[0124] In the above chemical formula 8, X and X' are each independently hydrogen or an alkali metal species (E), and at this time, the alkali metal species (E) may be Li, Na, or K, and preferably may be Na or K.

[0125] Above L 3 and L 4 is a leaving group removed during the polymerization reaction, and may independently be a halogen element such as F, Cl, Br, I, etc., and preferably may be an F or Cl element.

[0126] The second monomer can be prepared, for example, by sulfonating the first monomer as described in the following reaction scheme 1, and it is preferable to use a compound having a purity of 97% or higher. This is because, if a compound having a purity of less than 97% is used as the second monomer, side reactions may occur due to impurities.

[0127] [Reaction Formula 1]

[0128]

[0129]

[0130] Specific examples of the second monomer include disodium 3,3'-disulfonated-4,4'-dichlorodiphenylsulfone (SDCDPS), disodium 3,3'-disulfonated-4,4'-difluorodiphenylsulfone (SDFDPS), or a combination thereof, and among these, disodium 3,3'-disulfonated-4,4'-dichlorodiphenylsulfone (SDCDPS) is particularly preferred.

[0131] The second monomer may be included in an amount of 20 to 55 parts by weight, preferably 25 to 40 parts by weight, and more preferably 30 to 40 parts by weight, based on 100 parts by weight of the total weight of the first to third monomers combined. When the content of the second monomer among the total monomers satisfies the above range, the content of sulfonic acid groups in the cation exchange resin is appropriately formed, thereby realizing excellent ion exchange capacity.

[0132]

[0133] Next, the third monomer is a compound represented by the following chemical formula 9 or 10, which is intended to improve the chemical stability and mechanical properties of the cation exchange resin by reacting with the first monomer and the second monomer to form a thioether bond in the first repeating unit and the second repeating unit.

[0134] [Chemical Formula 9]

[0135]

[0136] In the above chemical formula 9, the Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )- and preferably, -S- or -O-. Meanwhile, the R 1 and R 2 Each may independently be a hydrogen atom, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group.

[0137] Above L 5 and L 6 is a leaving group removed during the polymerization reaction, and each can independently be a cation of an alkali metal species (E) or a hydrogen atom, and preferably, a hydrogen element.

[0138] [Chemical Formula 10]

[0139]

[0140] In the above chemical formula 10, L7 and L 8 is a leaving group removed during the polymerization reaction, and each can independently be a cation or a hydrogen atom of an alkali metal species (E), and preferably, a hydrogen element.

[0141] The third monomer may be, for example, 4,4'-thiobisbenzenethiol (TBBT), biphenyl-4,4'-dithiol, 4,4'-oxydibenzenethiol, bis(4-mercaptophenyl)sulfone, benzene-1,4-dithiol, and among these, 4,4'-thiobisbenzenethiol (TBBT) is particularly preferred.

[0142] It is preferable to use a third monomer having a purity of 98% or higher. This is because if a compound having a purity of less than 98% is used as the third monomer, side reactions may occur due to impurities.

[0143] The third monomer may be included in an amount of 30 to 60 parts by weight, preferably 30 to 50 parts by weight, and more preferably 35 to 50 parts by weight, based on 100 parts by weight of the total weight of the first to third monomers combined. When the content of the third monomer among the total monomers satisfies the above range, a cation exchange resin having excellent mechanical properties and chemical stability can be produced as the first and second monomers are bonded by a thioether group having a high bonding force.

[0144] Meanwhile, the reaction mixture may contain the first monomer: the second monomer in a molar ratio of 30:70 to 70:30, preferably 40:60 to 70:30, more preferably 50:50 to 70:30. When the first monomer and the second monomer in the reaction mixture are contained in the molar ratio, the molar ratio of the first repeating unit and the second repeating unit in the cation exchange resin is appropriately formed, so that ion exchange performance, chemical stability, and swelling characteristics can all be excellent.

[0145]

[0146] Next, the polymerization solvent is used to dissolve the first to third monomers to proceed with the polymerization reaction, and any solvent capable of dissolving the monomers is not particularly limited in type. For example, the polymerization solvent may be N-methyl-2-pyrrolidone (NMP), toluene, dimethyl acetamide (DMAc), N,N-dimethylformamide, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, or the like, which may be used alone or in combination. Preferably, the polymerization solvent may be N-methyl-2-pyrrolidone, toluene, dimethylacetamide, or a mixture thereof.

[0147] Meanwhile, the polymerization solvent preferably has high purity and low moisture content. If the polymerization solvent has low purity, impurities may adversely affect the polymerization reaction, and if the polymerization solvent has high moisture content, there may be a problem of low resin polymerization degree. Specifically, the polymerization solvent may have a purity of 99% or higher and a moisture content of less than 500 ppm.

[0148] The above polymerization solvent may be included in an amount that allows the polymerization reaction to have a solid concentration and viscosity that can occur smoothly.

[0149] For example, the polymerization solvent may be included in an amount such that the solids concentration in the reaction mixture is 10 wt% to 50 wt%, preferably 15 wt% to 40 wt%, and more preferably 15 wt% to 35 wt%.

[0150] Meanwhile, if necessary, the reaction mixture may further include a catalyst. The catalyst functions to activate the polymerization reaction, and examples thereof include K2CO3, CaCO3, CeCO3, and the like, which may be used alone or in combination. It is preferable to use a catalyst with a purity of 99% or higher. This is because, if the catalyst purity is low, side reactions may occur due to impurities.

[0151] Meanwhile, the catalyst may be included in an amount of 15 to 35 parts by weight, preferably 20 to 35 parts by weight, and more preferably 20 to 30 parts by weight, based on 100 parts by weight of the total weight of the first to third monomers. When the catalyst content satisfies the above range, the polymerization reaction promotion effect is excellent.

[0152]

[0153] Next, the above reaction mixture is polymerized to synthesize a cation exchange resin (step S2).

[0154] The above polymerization reaction can be carried out in the presence or absence of a catalyst, and the polymerization temperature can be 150°C to 200°C, preferably 160°C to 195°C, and more preferably 170°C to 195°C. When the polymerization reaction is carried out within the above temperature range, there is an effect of proceeding with polymerization while minimizing the occurrence of side reactions.

[0155]

[0156] Meanwhile, when a cation exchange resin is synthesized through a polymerization reaction as described above, a process of separating the synthesized resin, washing it with water, and drying it to obtain a solid cation exchange resin can be performed, if necessary (step S3).

[0157] Specifically, the synthesized resin is precipitated in a deionized water or isopropyl alcohol solvent, the precipitated resin is separated from the solution, and the separated resin is washed and dried to obtain a solid cation exchange resin.

[0158] Then, the above-mentioned solid cation exchange resin is redissolved in a solvent to form a liquid cation exchange resin composition (step S4).

[0159] As a solvent for the above re-dissolution, for example, N-methyl-2-pyrrolidone (NMP), dimethyl acetamide (DMAc), N,N-dimethylformamide (N,N-dimethylformamide), dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, etc. can be used, and preferably, N-methyl pyrrolidone (NMP), dimethyl acetamide (DMAc), or a mixture thereof can be used.

[0160] Meanwhile, the liquid cation exchange resin composition may have a solid content concentration of 10 wt% to 30 wt%, preferably 20 wt% to 30 wt%.

[0161] In addition, the liquid cation exchange resin composition may have a viscosity of 1,500 to 50,000 cP, preferably 2,000 to 30,000 cP. In this case, the viscosity is a value measured at 25°C using a Brookfield viscometer.

[0162] When the solid concentration and viscosity of the liquid cation exchange resin composition satisfy the above range, the formability and / or coatability are excellent when manufacturing an ion exchange membrane.

[0163] If the above process is additionally performed, KCl salt, moisture and / or gas generated during the polymerization process in the above process are removed, thereby further improving the ion exchange performance, chemical stability and mechanical properties of the cation exchange resin. In addition, the viscosity of the cation exchange resin can be adjusted through the re-dissolution process, thereby improving the formability of the ion exchange membrane.

[0164]

[0165] The method for manufacturing a cation exchange resin of the present invention as described above uses relatively inexpensive monomers, so the manufacturing cost is low and it is more economical than existing commercially available fluorine-based ion exchange resins.

[0166]

[0167] ion exchange membrane

[0168] Next, the ion exchange membrane according to the present invention will be described.

[0169] The ion exchange membrane according to the present invention may be an ion exchange membrane for separating an alkali metal species (M), and includes the cation exchange resin and / or cation exchange resin composition of the present invention described above. In this case, the alkali metal species (M) may be Li, Na, or K, and among these, may be Li in particular.

[0170] For example, the ion exchange membrane may be a molded membrane of a cation exchange resin composition according to the present invention. In this case, the molded membrane may be manufactured using membrane molding methods well known in the art, such as, for example, an immersion method, a casting method, a coating method, etc.

[0171] Specifically, the ion exchange membrane according to the present invention may include a cation exchange resin of the present invention including a first repeating unit represented by the above-described [chemical formula 1] and a second repeating unit represented by the above-described [chemical formula 2], and may further include a support as needed.

[0172] The support may include, for example, inorganic fibers, and the inorganic fibers may be, but are not limited to, glass wool, glass mat, ceramic wool, etc.

[0173] Alternatively, the support may be, for example, a porous support made of a polymer material. For example, the porous support may be a woven or nonwoven fabric including at least one selected from polyethylene, polypropylene, polybenzimidazole, polyvinylidene fluoride, polytetrafluoride, polyphenylene sulfide, polyetheretherketone, polyethersulfone, polyaryleneethersulfone, polyetherketone, polyamideimide, and polyetherimide.

[0174] In this case, the ion exchange membrane may be a cation exchange resin according to the present invention coated on the porous support.

[0175] The thickness of the cation exchange resin layer coated on the porous support may be 20 µm to 300 µm, preferably 20 µm to 200 µm, and more preferably 30 µm to 150 µm. When the thickness of the cation exchange resin layer satisfies the above range, there is an effect of suppressing excessive increase in membrane resistance while maintaining membrane durability.

[0176]

[0177] The ion exchange membrane for separating alkali metal species (M) according to the present invention as described above has excellent economic efficiency as it can be manufactured at a low cost while having performance at the same level as existing commercialized fluorine-based ion exchange membranes.

[0178] Specifically, the ion exchange membrane according to the present invention may have an ion exchange capacity (IEC) of 1.0 mEq / g to 2.0 mEq / g, preferably 1.1 mEq / g to 1.8 mEq / g, and more preferably 1.1 mEq / g to 1.7 mEq / g.

[0179] In addition, the ion exchange membrane according to the present invention may have a hydrogen ion conductivity of 0.02 S / cm to 0.12 S / cm, preferably 0.02 S / cm to 0.10 S / cm, and more preferably 0.02 S / cm to 0.09 S / cm at 25°C. When the ion exchange capacity and hydrogen ion conductivity of the ion exchange membrane satisfy the above ranges, ions of alkali metal species (M) can be effectively separated, and membrane electrical resistance can be minimized.

[0180] In addition, the ion exchange membrane for separation of alkali metal species (M) according to the present invention has excellent chemical stability, particularly alkali resistance, so that even when the pH fluctuates, the membrane is less likely to break or lose, and the membrane shape can be stably maintained.

[0181] In addition, the ion exchange membrane for separating alkali metal species (M) according to the present invention exhibits excellent durability with little swelling even when exposed to moisture. Specifically, when the ion exchange membrane is precipitated in water, the degree of swelling, which is the rate of change in membrane thickness before and after precipitation, may be 40% or less, preferably 5% to 40%, more preferably 5% to 35%, and even more preferably 5% to 30%. When the swelling satisfies the above range, there is an effect of minimizing performance degradation due to membrane deformation.

[0182] The ion exchange membrane according to the present invention as described above can be usefully applied to an electrodialysis device for lithium extraction.

[0183]

[0184] Electrodialysis device for lithium extraction

[0185] Next, an electrodialysis device for lithium extraction according to the present invention will be described.

[0186] The electrodialysis device for lithium extraction according to the present invention may include an ion exchange membrane for separating alkali metal species (M) according to the present invention as a cation exchange membrane. When the ion exchange membrane according to the present invention is applied to the electrodialysis device for lithium extraction, good durability can be secured with a cheaper manufacturing process compared to when a fluorinated ion exchange membrane is applied. In addition, it can secure economic feasibility in separating and concentrating lithium hydroxide (LiOH) compared to expensive fluorinated ion exchange membranes.

[0187]

[0188] An electrodialysis device for lithium extraction is a device that selectively passes ions through an ion exchange membrane in an electric field to separate lithium ions in a solution. FIG. 2 illustrates an example of an electrodialysis device for lithium extraction according to the present invention. Hereinafter, an electrodialysis device for lithium extraction according to the present invention will be described with reference to FIG. 2.

[0189] Referring to FIG. 2, an electrodialysis device (100) for lithium extraction according to the present invention includes an oxidation electrode (10) and a reduction electrode (20) which are arranged to face each other, a cation exchange membrane (30) and an anion exchange membrane (40) which are arranged alternately between the oxidation electrode (10) and the reduction electrode (20), and a spacer (50) which is arranged between the cation exchange membrane and the anion exchange membrane, wherein the cation exchange membrane (30) is an ion exchange membrane for separating alkali metal species (M) according to the present invention. Meanwhile, a bipolar membrane (60, 70) may further be included between the electrode and the ion exchange membrane, if necessary.

[0190] The above oxidation electrode (10) and reduction electrode (20) are for providing electromotive force to the electrodialysis device. The oxidation electrode (10) serves as the anode and provides a force to pull anions from the electrodialyzed treatment water and pass through the anion exchange membrane (40), and the reduction electrode (20) serves as the cathode and provides a force to pull cations from the treatment water and pass through the cation exchange membrane (30).

[0191] The above cation exchange membrane (30) and anion exchange membrane (40) are for selectively permeating and separating cations and anions, respectively, and a plurality of cation exchange membranes (30) and a plurality of anion exchange membranes (40) are alternately arranged between the oxidation electrode (10) and the reduction electrode (20). At this time, the cation exchange membrane (30) is made of an ion exchange membrane including a cation exchange resin according to the present invention.

[0192] The above spacer (50) is placed between the cation exchange membrane (30) and the anion exchange membrane (40) to separate the cation exchange membrane (30) and the anion exchange membrane (40) and to secure a space through which the treated water can pass, and is made of a non-insulating material that allows the movement of ions and electrolytes.

[0193] Meanwhile, the bipolar membrane (60, 70) is a membrane in which a cation exchange layer and an anion exchange layer are combined, and is arranged in a reverse bias state in which the cation exchange layer of the bipolar membrane is arranged toward the cathode and the anion exchange layer is arranged toward the anode. The bipolar membrane plays a role in decomposing water molecules into hydrogen ions and hydroxide ions. When the bipolar membrane is provided, the anions and cations separated from the ion exchange membrane are separated from the bipolar membrane. + Wow OH - It can react with ions and be converted into a compound form that is easy to recover and / or use.

[0194]

[0195] Next, a method for extracting lithium using an electrodialysis device (100) as described above will be described.

[0196] First, the treated water (F) containing lithium is introduced between the cation exchange membrane (30) and the anion exchange membrane (40), and water is introduced between the bipolar membrane (60) and the electrodes (10, 20). At this time, the treated water (F) containing lithium may be, for example, waste liquid generated from a waste lithium secondary battery or a lithium secondary battery manufacturing process, including lithium sulfate (LiSO4), but is not limited thereto.

[0197] After the treated water (F) and water are added, or at the same time as they are added, voltage is applied to the oxidation electrode (10) and reduction electrode (20). When voltage is applied to the electrodes, water is decomposed in the bipolar membrane, and H + and OH - Ions are generated and lithium ions (Li) in the treated water + ) passes through the cation exchange membrane (30) and moves toward the reduction electrode (20), and the anions (e.g., SO4) contained in the treated water 2- ) passes through the anion exchange membrane (40) and moves toward the oxidation electrode (10).

[0198] Lithium ions (Li) moved toward the oxidation electrode (10) + ) is OH generated in the bipolar membrane - LiOH(P) is generated by combining with ions, and lithium can be extracted from the treated water by recovering the LiOH. Meanwhile, the anion (SO4) moved toward the reduction electrode (20) 2- ) is H + It can be combined with ions, and the anion and H + The combined products of ions and residual treated water can be discharged outside the electrodialysis device through a separate path from LiOH.

[0199] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0200]

[0201] Examples and Comparative Examples

[0202] Example 1

[0203] <Manufacturing of cation exchange resin>

[0204] A 500 mL round flask was equipped with a gas inlet, Dean-Stark trap, condenser, thermometer, and stirrer, and left in a nitrogen atmosphere for 30 minutes.

[0205] 18.56 g of DCDPS, 13.61 g of SDCDPS, and 23.10 g of TBBT as monomers, 14.46 g of K2CO3 as a catalyst, and 207 g of NMP as a solvent were added to the round flask, stirred, and dissolved to prepare a reaction mixture.

[0206] Thereafter, the reaction mixture was heated to 150°C over 1 hour, then heated to 175°C over 2 hours, and the polymerization reaction was maintained while maintaining the temperature until the desired viscosity was reached.

[0207] Afterwards, salt by-products were removed through a filter, and the resultant was precipitated in water to obtain a cation exchange resin. After sequentially washing with water and isopropyl alcohol (IPA), residual impurities were removed, and the resultant was dried in a depressurized dryer at 80°C for 24 hours to obtain a solid cation exchange resin (sulfonated polythioethersulfone, SPTES). Then, the resultant was dissolved in an NMP solvent to a solid concentration of 20 wt% to obtain a transparent liquid cation exchange resin composition.

[0208] <Ion exchange membrane manufacturing>

[0209] The above liquid cation exchange resin composition was cast on a glass plate using a doctor blade and then dried in an oven at 80°C for 12 hours to produce an ion exchange membrane.

[0210] Example 2

[0211] A cation exchange resin composition and an ion exchange membrane including the same were manufactured in the same manner as in Example 1, except that 15.91 g of DCDPS and 18.15 g of SDCDPS were added when manufacturing the cation exchange resin.

[0212] Example 3

[0213] A cation exchange resin composition and an ion exchange membrane including the same were manufactured in the same manner as in Example 1, except that 13.26 g of DCDPS and 22.68 g of SDCDPS were added when manufacturing the cation exchange resin.

[0214] Comparative Example 1

[0215] When manufacturing the above cation exchange resin, a cation exchange resin composition and an ion exchange membrane including the same were manufactured in the same manner as in Example 1, except that 18.56 g of DCDPS, 13.61 g of SDCDPS, and 17.21 g of BP (biphenol) were added as monomers to manufacture a sulfonated polyethersulfone (SPES) resin.

[0216] Comparative Example 2

[0217] When manufacturing the above cation exchange resin, a cation exchange resin composition and an ion exchange membrane including the same were manufactured in the same manner as in Example 1, except that 15.91 g of DCDPS, 18.15 g of SDCDPS, and 17.21 g of BP (biphenol) were added as monomers to manufacture sulfonated polyethersulfone (SPES).

[0218] Comparative Example 3

[0219] An ion exchange membrane was manufactured using a commercially available sulfonated PPO ion exchange resin (InnoChemTech InnoSol-C100).

[0220]

[0221] The composition of the reaction solution used in the production of the cation exchange resin of Examples 1 to 3 and Comparative Examples 1 to 2 is shown in [Table 1] below.

[0222]

[0223] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2Wt(g)mol%Wt(g)mol%Wt(g)mol%Wt(g)mol%Wt(g)mol%MonomerDCDPS18.5635.015.9130.013.2625.018.5635.015.9130.0SDCDPS13.6115.018.1520.022.6825.013.6115.018.1520.0TBBT23.1050.023.1050.023.150.0----BP------17.2150.017.2150.0CatalystK2CO314.46-14.46-14.46-14.46-14.46-SolventNMP207-207-207-207-207-

[0224] In the above Table 1, the mol% is the mol% of each monomer with respect to the total mole number of all monomers in the reaction solution, DCDPS is 4,4'-Dichlorodiphenyl sulfone (CAS No. 80-07-9, molecular weight 287.15 g / mol), SDCDPS is Disodium 3,3'-disulfonated-4,4'-dichlorodiphenylsulfone (CAS No. 51698-33-0, molecular weight 491.25 g / mol), TBBT is 4,4'-Thiobisbenzenethiol (CAS No. 19362-77-7, molecular weight: 250.39 g / mol), BP is biphenol (biphenol, molecular weight: 186.21 g / mol), and NMP is It is N-methylpyrrolidone.

[0225] Experimental Example 1: Evaluation of Ion Exchange Capacity

[0226] The ion exchange membranes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 were immersed in a 1.5 M sulfuric acid aqueous solution at room temperature for 24 hours, washed with deionized water, and then dried in a vacuum oven at 80°C. The dried membranes were cut into 1 cm wide and 3 cm long sizes to prepare samples. The sample weights were measured and immersed in 100 mL of a 0.01 M NaCl aqueous solution for 24 hours. Thereafter, the pH was titrated to 7 with a 0.01 M NaOH aqueous solution using an acid-base automatic titrator (Metrohm 888 Titrando). The ion exchange capacity IEC was measured by substituting the sample weight and the volume of the NaOH aqueous solution used for titration into Equation (1) below. The measurement results are shown in [Table 2] below.

[0227] Equation (1):

[0228]

[0229] (v: volume of NaOH aqueous solution used for titration (mL), c: molar concentration of NaOH aqueous solution (M), w: sample weight (g))

[0230]

[0231] Experimental Example 2: Evaluation of Hydrogen Ion Conductivity

[0232] The ion exchange membranes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 were immersed in a 1.5 M sulfuric acid solution at room temperature for 24 hours, washed with deionized water, and then stored in deionized water. Then, the thickness of the immersed ion exchange membranes was measured, mounted on a conductivity measurement cell, placed in a 25°C oven, and connected to an AC impedance measurement device (Neoscience, VSP-300) to evaluate the hydrogen ion conductivity. The measurement results are shown in [Table 2] below.

[0233] Ion exchange capacity (IEC) [mEq / g] Hydrogen ion conductivity [S / cm] Example 11.10.021 Example 21.50.054 Example 31.70.082 Comparative example 11.30.025 Comparative example 21.70.061 Comparative example 31.60.035

[0234] Through the above [Table 2], it can be confirmed that the ion exchange capacity and hydrogen ion conductivity of Examples 1 to 3 are at the same level as those of Comparative Examples 1 to 3. In addition, in the case of Examples 1 to 3, it can be confirmed that the ion exchange capacity and hydrogen ion conductivity increase as the molar % of SDCDPS in the reaction solution increases.

[0235]

[0236] Experimental Example 3: pH Stability Evaluation

[0237] After preparing solutions with a pH range of 1 to 14 using HCl and KOH aqueous solutions, the ion exchange membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were precipitated in each pH solution. After 30 days, the shape of the membranes was maintained and the amount of compound residue was measured to evaluate the pH stability of each ion exchange membrane. The results are shown in [Table 3] below.

[0238] pH Stability Example 1 ○ Example 2 ○ Example 3 ○ Comparative Example 1Ⅹ Comparative Example 2Ⅹ Comparative Example 3Ⅹ

[0239] In the above [Table 3], the ○ mark means that the ion exchange membrane does not break at each pH and maintains its shape, and the amount of compound remaining is 80% or more, and the Ⅹ mark means that the membrane shape is not maintained at each pH and breaks or the amount of compound remaining is 60% or less. Through the above [Table 3], it can be confirmed that the pH stability of the ion exchange membranes of Examples 1 to 3 is superior to that of Comparative Examples 1 to 3.

[0240]

[0241] Experimental Example 4: Swelling Evaluation

[0242] Each of the ion exchange membranes manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 was immersed in water at 25°C for 48 hours, and the rate of change in the volume of the ion exchange membrane before and after immersion was measured to evaluate the degree of swelling (%) defined by the following equation (2).

[0243] Equation (2): Swelling (%) = {(volume of ion exchange membrane after immersion - volume of ion exchange membrane before immersion) / volume of ion exchange membrane before immersion} × 100

[0244] The measurement results are shown in [Table 4] below.

[0245] Swelling degree (%) Example 110 Example 216 Example 328 Comparative Example 125 Comparative Example 235 Comparative Example 342

[0246] Through the above [Table 4], it can be confirmed that the ion exchange membranes manufactured by Examples 1 to 3 have superior swelling characteristics compared to the ion exchange membranes manufactured by Comparative Examples 1 to 2. In addition, in the case of the ion exchange membrane of Comparative Example 1 manufactured using a cation exchange resin applying biphenol instead of a thiol-based monomer, it was found that the swelling characteristics were lower compared to the ion exchange membrane of Example 1 manufactured using a cation exchange resin having the same DCDPS and SDCDPS contents and applying a thiol-based monomer.

Claims

1. A first repeating unit represented by the following chemical formula 1; and A cation exchange resin comprising a second repeating unit represented by the following chemical formula 2. [Chemical Formula 1] (In the above chemical formula 1, X and X' are each independently hydrogen or an alkali metal species (E), and A 1 is represented by the following chemical formula 3 or the following chemical formula 4.) [Chemical Formula 2] (In the above chemical formula 2, A 2 is represented by the following chemical formula 3 or the following chemical formula 4.) [Chemical Formula 3] (In the above chemical formula 3, Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and, R 1 and R 2 are each independently hydrogen, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group.) [Chemical Formula 4] 2. In claim 1, A cation exchange resin, wherein the first repeating unit is represented by the following chemical formula 1A. [Chemical Formula 1A] (In the above chemical formula 1A, X and X' are each independently hydrogen or an alkali metal species (E), and A 1 is represented by the following chemical formula 3 or the following chemical formula 4.) [Chemical Formula 3] (In the above chemical formula 3, Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and, R 1 and R 2 are each independently a hydrogen atom, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group.) [Chemical Formula 4] 3. In claim 1, The above Z 1 Silver -S- or -O-, cation exchange resin.

4. In claim 1, A in the above chemical formula 1 1 And the above A in the above chemical formula 2 2 A cation exchange resin represented by the above chemical formula 3.

5. In claim 1, A in the above chemical formula 1 1 And the above A in the above chemical formula 2 2 A cation exchange resin represented by the above chemical formula 4.

6. In claim 1, A cation exchange resin comprising the first repeating unit and the second repeating unit in a molar ratio of 30:70 to 70:

30.

7. In claim 1, The above cation exchange resin is a cation exchange resin comprising a repeating unit represented by the following chemical formula 5. [Chemical Formula 5] (In the above chemical formula 5, X and X' are each independently hydrogen or an alkali metal species (E), Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and, R 1 and R 2 are each independently a hydrogen atom, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group, m1 is a positive number greater than 0 and less than or equal to 1, n1 is an integer between 50 and 1,000.) 8. In claim 7, The above m1 is a positive cation exchange resin of 0.3 to 0.

7.

9. In claim 1, The above cation exchange resin is a cation exchange resin comprising a unit represented by the following chemical formula 6. [Chemical Formula 6] (In the above chemical formula 6, X and X' are each independently hydrogen or an alkali metal species (E), m2 is a positive number greater than 0 and less than or equal to 1, n2 is an integer between 50 and 1,000.) 10. In claim 9, The above m2 is a positive cation exchange resin of 0.3 to 0.

7.

11. In claim 1, A cation exchange resin, wherein the alkali metal species (E) is sodium (Na) or potassium (K).

12. In claim 1, The above cation exchange resin is a cation exchange resin having a weight average molecular weight of 50,000 g / mol to 500,000 g / mol.

13. A cation exchange resin composition comprising the cation exchange resin of any one of claims 1 to 12.

14. An ion exchange membrane for separating alkali metal species (M) obtained as a molded membrane of the cation exchange resin composition of claim 13.

15. An ion exchange membrane for separating alkali metal species (M), comprising the cation exchange resin of any one of claims 1 to 12.

16. In claim 15, An ion exchange membrane for separating an alkali metal species (M) further comprising a support.

17. In claim 16, The support comprises inorganic fibers, An ion exchange membrane for separating alkali metal species (M), wherein the cation exchange resin is impregnated on the support.

18. In claim 16, An ion exchange membrane for separating alkali metal species (M), wherein the above-mentioned inorganic fiber comprises at least one selected from the group consisting of glass mat, glass wool, and ceramic wool.

19. In claim 16, The above support is a porous polymer film, An ion exchange membrane for separating alkali metal species (M), wherein the cation exchange resin is coated on the porous support.

20. In claim 19, An ion exchange membrane for separating alkali metal species (M), wherein the thickness of the cation exchange resin coated on the porous support is 20 µm to 300 µm.

21. In claim 15, The above ion exchange membrane is an ion exchange membrane for separating alkali metal species (M) having an ion exchange capacity (IEC) of 1.0 mEq / g to 2.0 mEq / g.

22. In claim 15, The above ion exchange membrane is an ion exchange membrane for separating alkali metal species (M) having a hydrogen ion conductivity of 0.02 S / cm to 0.12 S / cm at 25°C.

23. In claim 15, An ion exchange membrane for separating alkali metal species (M), the swelling of which is expressed by the following equation (2) and measured by immersing the ion exchange membrane in water at 25°C for 48 hours, is 40% or less. Equation (2): Swelling (%) = {(volume of ion exchange membrane after immersion - volume of ion exchange membrane before immersion) / volume of ion exchange membrane before immersion} × 100 24. In claim 15, An ion exchange membrane for separating alkali metal species (M), wherein the alkali metal species (M) is lithium (Li).

25. An electrodialysis device for lithium extraction comprising an ion exchange membrane for separating alkali metal species (M) of claim 15.

26. A method for producing a cation exchange resin, comprising a step of polymerizing a reaction mixture comprising a first monomer represented by the following chemical formula 7; a second monomer represented by the following chemical formula 8; and a third monomer represented by the following chemical formula 9 or the following chemical formula 10; and a polymerization solvent. [Chemical Formula 7] (In the above chemical formula 7, L 1 and L 2 are leaving groups removed during the above polymerization reaction, and each is independently a halogen element.) [Chemical Formula 8] (In the above chemical formula 8, X and X' are each independently hydrogen (H) or an alkali metal species (E), L 3 and L 4 are leaving groups removed during the above polymerization reaction, and each is independently a halogen element.) [Chemical Formula 9] (In the above chemical formula 9, Z 1 -S-, -O-, -C(O)-, or -C(R 1 R 2 )-and, R 1 and R 2 are each independently hydrogen, a C1 to C2 alkyl group, a halogen, or a halogen-substituted C1 to C2 alkyl group, L 5 and L 6 are leaving groups removed during the polymerization reaction, and each independently represents a cation or hydrogen atom of an alkali metal species (E). [Chemical Formula 10] (In the above chemical formula 10, L 7 and L 8 are leaving groups removed during the polymerization reaction, and each independently represents a cation or hydrogen atom of an alkali metal species (E).

27. In claim 26, Above L 5 , the above L 6 , the above L 7 , and the above L 8 A method for manufacturing a cation exchange resin, which is a hydrogen atom.

28. In claim 26, A method for producing a cation exchange resin, wherein the above reaction mixture contains the first monomer: the second monomer in a molar ratio of 30:70 to 70:

30.

29. In claim 26, A method for producing a cation exchange resin, wherein the above polymerization reaction is performed at 150°C to 200°C.

30. In claim 26, A method for producing a cation exchange resin, wherein the above polymerization reaction is performed in the presence of a catalyst.

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