KR102057993B1 - Ion-exchange membrane with improved monovalent ion selectivity and preparation method thereof - Google Patents

Abstract

The present invention relates to an ion exchange membrane with improved monovalent ion selectivity and a method for manufacturing the same. More specifically, the present invention relates to manufacture of a pore-filled ion exchange membrane which can improve monovalent ion selectivity and membrane performance related to contamination resistance by surface modifying the ion exchange membrane.

Description

Ion-exchange membrane with improved monovalent ion selectivity and preparation method

The present invention relates to an ion exchange membrane having improved monovalent ion selectivity and a method for producing the same. More specifically, the present invention relates to the preparation of pore-filled ion exchange membranes that improve membrane performance in terms of monovalent ion selectivity and contamination resistance through surface modification of the ion exchange membrane.

Interest in desalination and energy conversion and storage, which are environmentally friendly processes using ion exchange membranes, has increased. Among these processes, high performance ion exchange membranes are further emphasized as ion exchange membranes are used in various applications such as desalination, electrodialysis, diffusion dialysis, and energy generation processes such as fuel cells and reverse electrodialysis.

In recent years, various studies have been conducted to modify the surface in order to reform the performance of the ion exchange membrane.

Korean Patent Application Publication No. 10-1586769 (January 13, 2016) filed by the present applicant provides an ion exchange membrane coated with an ion exchange polymer solution having opposite polarities on an anion exchange membrane or a cation exchange membrane, and a method of manufacturing the same. It was.

However, it was necessary to study to obtain a high purity product by avoiding scaling on the membrane surface and selectively transmitting only monovalent ions.

Republic of Korea Patent Publication No. 10-1586769 (2016.01.13)

The present inventors have attempted to provide an ion exchange membrane capable of obtaining a product of high purity by avoiding scaling on the membrane surface and selectively transmitting only monovalent ions.

More specifically, an object of the present invention is to provide a pore-filled ion exchange membrane and a method for preparing the same, which improves the membrane performance in terms of monovalent ion selectivity and contamination resistance through surface modification of the ion exchange membrane.

In addition, compared to conventional commercially available ion exchange membranes, the thickness is very thin, so that the processing capacity can be further increased in the same volume, and even though the thickness is very thin, the ion exchange capacity can be further increased by more than 20%, the electrical resistance is low, and the water content It is low, to provide a pore-filled ion exchange membrane and a method for manufacturing the same, the primary ion selectivity is increased by more than 30%, the ratio of the membrane resistance to monovalent ion selectivity can be significantly increased.

In order to solve the above problems, as a result, by forming a modified layer containing a conductive resin having a compact structure for excluding divalent ions on the surface of the pore-filled ion exchange membrane and reduced graphene particles exhibiting hydrophobicity, 1 The present invention was completed by discovering that ion selectivity can be greatly improved.

 One aspect of the present invention provides an ion exchange membrane having an improved monovalent ion selectivity comprising a modified layer including a conductive resin and reduced graphene particles on a surface of a pore-filled ion exchange membrane.

In one aspect of the present invention, the pore-filling ion exchange membrane is immersed and cured in a mixed solution containing a monomer, a co-solvent, a crosslinking agent, and an initiator having a base capable of introducing or introducing a crosslinkable monomer, a cation exchanger or an anion exchanger into a porous substrate. It may be prepared by.

In one aspect of the invention, the porous substrate may be a porous film or nonwoven fabric of a polyolefin-based material.

In one embodiment of the present invention, the crosslinkable monomer is styrene when the anion exchange membrane, an acrylic monomer or an acrylic oligomer when the cation exchange membrane,

Monomers having the base include monomers containing a cation exchange group selected from sulfonic acid group, carboxyl group, phosphonic group, phosphonic group, asonic group, selinolic group and metal salts thereof; Or a monomer containing any one or more anion exchange groups selected from quaternary ammonium salts, primary to tertiary amines, quaternary phosphonium groups, and tertiary sulfonium groups.

In one aspect of the invention, the conductive resin may be polypyrrole.

In one aspect of the present invention, the modified layer may be a weight ratio of the conductive resin: reduced graphene particles 1: 0.1 to 1 by weight ratio.

In one aspect of the present invention, the ion exchange membrane may be a water contact angle of 60 to 90 degrees.

In one aspect of the present invention, the ion exchange membrane may have an ion exchange capacity of 1.5 meq. / G or more.

In one aspect of the present invention, when the ion exchange membrane is a monovalent ion selectivity of the ion exchange membrane that does not include the modifying layer is M1, the monovalent ion selectivity of the ion exchange membrane including the modifying layer is M2, It may be to satisfy the relation 1.

[Relationship 1]

30% ≤ (M2-M1) / M1 × 100 ≤ 300%

Another embodiment of the present invention is a) coating a mixture containing a conductive resin and graphene oxide on a pore-filled ion exchange membrane;

b) reducing the graphene oxide;

It provides a method for producing an ion exchange membrane with improved monovalent ion selectivity comprising a.

In one aspect of the invention, the pore filling ion exchange membrane

a-1) immersing or coating a porous substrate in a mixed solution comprising a crosslinkable monomer, a cation exchanger or an anion exchanger, or a monomer, a cosolvent, a crosslinking agent and an initiator having a base capable of introducing;

a-2) hardening by irradiating ultraviolet rays to the porous substrate immersed in the mixed solution;

It may be prepared to include.

Compared to conventional commercial ion exchange membranes, the ion exchange membrane according to the present invention has a low electric resistance, high ion conductivity, high monovalent ion selectivity, and easy mass production by a roll-to-roll process. There is this.

In addition, the method for preparing an ion exchange membrane according to the present invention is to prepare a monomer by using a monomer having a base containing an ion exchange group as an ionomer, and impregnated the porous film in the prepared monomer and reacted through light irradiation to form a pore filling anion When the exchange membrane is prepared and the ion exchange membrane is prepared using a monomer having a base, the post-treatment step for introducing the ion exchange group is not included, and thus, the process is simplified. In particular, this is a great advantage because it enables mass production.

1 and 2 illustrate a method for measuring monovalent ion selectivity according to an embodiment.

DETAILED DESCRIPTION Hereinafter, the present invention will be described in more detail with reference to the accompanying examples or embodiments. However, the following specific examples or examples are only one reference for describing the present invention in detail, but the present invention is not limited thereto and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used in the description in the present invention are only for effectively describing specific embodiments and are not intended to limit the present invention.

Also, the singular forms used in the specification and the appended claims may be intended to include the plural forms as well, unless the context clearly indicates otherwise.

In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In one embodiment of the present invention, the pore-filled ion exchange membrane is a ion-exchange polymer having a polyolefin-based (eg, polyethylene, polypropylene, etc.) porous film or non-woven substrate (polymer support) having a thin thickness of 50 μm or less It means the base membrane (monopolar membrane) filled with. The term 'base membrane' refers to a membrane structure forming a skeleton of an ion exchange membrane. A feature of the base film used in the present invention is that a polymer support (eg, a polyolefin-based substrate) having a thin thickness of 50 μm or less is used. The polymer support is inexpensive and has the advantage of having excellent mechanical properties in spite of its thin thickness. The preparing of the base membrane may use a known general method and may be commercially available.

More specifically, the pore-filled ion exchange membrane is prepared by immersing and curing a porous substrate in a mixed solution comprising a crosslinkable monomer, a cation exchange group or an anion exchanger-containing monomer or co-solvent, a crosslinking agent, and an initiator. It may be.

The crosslinkable monomer may be styrene in the case of the anion exchange membrane, and an acrylic monomer or an acrylic oligomer in the case of the cation exchange membrane.

The monomer having a base includes a sulfonic acid group (-SO ₃ H), a carboxyl group (-COOH), a phosphonic group (-PO ₃ H ₂ ), a phosphonic group (-HPO ₂ H), an asonic group (-AsO ₃ H ₂ ), monomers containing a cation exchange group selected from selinolic groups (-SeO ₃ H) and metal salts thereof; Or quaternary ammonium salts (-NH ₃ ), primary to tertiary amines (-NH ₂ , -NHR, -NR ₂ ), quaternary phosphonium groups (-PR ₄ ) and tertiary sulfonium groups (-SR ₃ ) It may be selected from a monomer containing any one or more anion exchange group selected. Such monomers may be mixed with water or an organic solvent to form a solution, or may be liquid, and any one or two or more mixtures may be used, and any monomer having a cation exchange group or an anion exchange group or introduced after polymer polymerization is not limited thereto. Do not.

The cosolvent may be used without limitation so long as it can dissolve all of the crosslinkable monomer and the monomer having a base, a crosslinking agent and an initiator.

Specifically, for example, the base membrane may be an anion exchange membrane. As the monomer for producing the anion exchange membrane, for example, styrene may be used, and as the monomer having a base, vinylbenzyl trimethyl ammonium chloride may be used. Divinylbenzene may be used as the crosslinking agent, and benzophenone may be used as the photoinitiator, but is not limited thereto.

In addition, the base membrane may be a cation exchange membrane. As a monomer for producing a cation exchange membrane, for example, an acrylic monomer or an acrylic oligomer may be used, and the use of an acrylic oligomer may be better with a photopolymer. Specifically, poly (ethylene glycol) diacrylate, Aromatric urethane acrylate and the like can be used. Commercialized examples may include, but are not limited to, A-1000 (Mn = 2500). As the monomer having a base, 2-acrylamido-3 methylpropanesulfonic acid (AMSA) may be used. Divinylbenzene may be used as the crosslinking agent, and benzophenone may be used as the photoinitiator, but is not limited thereto.

 In one embodiment of the present invention, preparing the pore-filled ion exchange membrane (base membrane),

a-1) immersing or coating a porous substrate in a mixed solution comprising a crosslinkable monomer, a cation exchanger or an anion exchanger, or a monomer, a cosolvent, a crosslinking agent and an initiator having a base capable of introducing;

a-2) hardening by irradiating ultraviolet rays to the porous substrate immersed in the mixed solution;

It may include.

In the present invention, the pore-filling ion exchange membrane was prepared as a monomer by using a monomer having a base containing an ion exchange group as an ionomer, and the pore-filling anion exchange membrane was reacted through light irradiation after impregnating the prepared monomer with a porous film. Prepared. When preparing an ion exchange membrane using a monomer having a base, the post-treatment step for introducing the ion exchange group is not included, so the process is simplified. This is a big advantage when considering mass production. Monomers with bases have high solubility in water, so water is mainly used as a solvent. However, since the crosslinking agent and the initiator added together are hydrophobic, co-solvents capable of dissolving both of the monomer having a base, the crosslinking agent, and the initiator are required.

In an aspect of the present invention, the ion exchange membrane having improved monovalent ion selectivity is characterized in that it comprises a modified layer including a conductive resin and reduced graphene particles on the surface of the pore-filled ion exchange membrane.

The conductive resin is used to exclude divalent ions by giving a charge to the surface of the ion exchange membrane, but is not limited to a polypyrrole may be used, in the case of using a polypyrrole by a compact structure of polypyrrole Can be better excluded, and the monovalent ion selectivity can be further improved.

The reduced graphene particles are used to impart hydrophobicity, and by using them, the surface of the ion exchange membrane may be hydrophobized, specifically, the physical properties of the water contact angle of 60 to 90 degrees may be satisfied, and the hydration radius may be in this range. It is better because large divalent ions can be selectively excluded. In addition, by using a graphene oxide (GO) having a large polarity, that is, a high hydrophilicity, as a raw material, it is possible to secure excellent coating property by increasing dispersibility in a solvent. The hydrophobicity of the surface is then increased by making it into a reduced graphene oxide (rGO) state. Increased hydrophobicity can reduce the migration of hydrated polyvalent ions. In addition, rGO, although hydrophobic, contains charged groups on its surface, which plays a role in controlling charge density on the surface, and has the advantage of reducing crack generation as a two-dimensional material. In addition, as in the present invention, it has a characteristic of forming a stable coating layer through interaction with the polypyrrole constituting the composite material (hydrogen bond, π-π stacking, electrostatic attraction, etc.). In addition, by forming a thin layer, it does not significantly increase the resistance and has the advantage of enabling the separation of ions effectively.

Although the mixing ratio of the conductive resin and the reduced graphene particles is not limited, the weight ratio of the conductive resin: the reduced graphene particles may be 1: 0.1 to 1 by weight. It is possible to provide an ion exchange membrane having a low water content, a high ion exchange capacity, and a low electrical resistance, as well as further improving the monovalent ion selectivity desired in the above range.

The method for producing an ion exchange membrane having improved monovalent ion selectivity comprises the steps of: a) coating a mixed solution containing a conductive resin and graphene oxide on a pore-filled ion exchange membrane;

b) reducing the graphene oxide;

It includes.

The coating in step a) includes both dipping or application.

In the preparation of the mixed solution, any solvent may be used as long as it can dissolve the conductive resin, and specifically, for example, acetonitrile may be used. In addition, the content of the conductive resin may be used in the preparation of the mixed solution, 1 to 10% by weight, more preferably 3 to 8% by weight, and more preferably 4 to 6% by weight. In the above range, the membrane resistance is low and the ion exchange capacity is high and the number of ion mobility is high, thereby providing an optimal coating condition, and can provide a higher ion exchange capacity than a commercially available product. In addition, the content of the graphene oxide may be included in a weight ratio of 1: 0.1 to 1 compared to the conductive resin, the monovalent ion selectivity of the target in the above range is further improved, the moisture content is low, the ion exchange capacity is It is possible to provide an ion exchange membrane having a high and low electrical resistance.

In the step b), the reducing may be specifically, for example, impregnation in an aqueous solution containing a reducing catalyst such as FeCl ₃ , and then may be an acid treatment by impregnation with an aqueous solution of HCl. In addition, after washing with distilled water may be impregnated with NaCl and neutralized.

The ion exchange membrane according to an aspect of the present invention may have a water contact angle of 60 to 90 degrees. In addition, the ion exchange capacity may be 1.5 meq. / G or more, more specifically 1.5 to 3 meq. / G.

The ion exchange membrane according to an aspect of the present invention may be 5 ~ 50 ㎛ thickness.

In addition, the ion exchange membrane satisfies the following relation 1 when the monovalent ion selectivity of the ion exchange membrane not including the modified layer is M1, and the monovalent ion selectivity of the ion exchange membrane including the modified layer is M2. It may be.

[Relationship 1]

30% ≤ (M2-M1) / M1 × 100 ≤ 300%

Specifically, the monovalent ion selectivity may be improved by 30% or more, more specifically 30 to 300% by including the modified layer, compared to the ion exchange membrane that does not include the modified layer.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following Examples and Comparative Examples are only examples for explaining the present invention in more detail, the present invention is not limited by the following Examples and Comparative Examples.

The physical properties were evaluated as follows.

1. Water uptake (WU): This was calculated by measuring the difference between the wet and dry weights of the membrane.

2. Ion-exchange capacity (IEC): The ion-exchange capacity of Cl-- was quantitatively analyzed using a silver titration method.

3. Evaluation of electrical resistance (ER): After measuring in 0.5 M NaCl aqueous solution and 0.5 M HCl using a self-made 2-point probe clip cell, the electrical resistance was evaluated by the following equation. .

는 LCZ 미터에서 관측된 임피던스 값이며 θ 는 위상각을 의미한다.In this expression

Is the impedance value observed from the LCZ meter and θ is the phase angle.

): 2-compartment diffusion cell을 이용한 emf 방법으로 측정되었으며 계산식은 다음과 같다. 4. Ion transport number

): It was measured by emf method using 2-compartment diffusion cell.

Where Em is the measured cell potential, R is the gas constant, T is the absolute temperature, F is the Faraday constant, and CL and CH are the NaCl solution concentrations of 1 mM and 5 mM, respectively. The cell potential was measured by connecting a pair of Ag / AgCl electrodes to a digital voltmeter.

Comparative Example 1

Commercial membranes of anion exchange membranes (AMX, Astom, Japan) were used.

Comparative Example 2 Preparation of Anion Exchange Membrane

The porous substrate (9 μm, W-SCOPE Korea, prototype) was washed in acetone solvent for 3 hours and dried in an oven.

Subsequently, the washed porous substrate was impregnated with the monomer solution to fill the pores with monomers, and after lamination with two release films, a pore-filled anion exchange membrane was prepared by light irradiation for 5 minutes using a 1 KW UV lamp.

The monomer solution was a mixture of styrene (crosslinkable monomer) and vinylbenzyl trimethyl ammonium chloride (monomer) having a base in a 1: 1 molar ratio, and 80 wt% of the total polymer weight was used. Used. At this time, ethanol was used as a co-solvent to dissolve the monomer having a base and styrene, and ethanol was added to 1/3 of the weight ratio of the monomer having a base. Trimethylolpropane triacrylate (TMPT) was used as a crosslinking agent, and 20 wt% of the total polymer weight was used. (Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide) was used as an initiator and 5 parts by weight based on the total monomer weight was used.

Examples 1 to 5 Preparation of Anion Exchange Membrane

The mixed solution containing the conductive resin and graphene oxide was coated on the pore-filled anion exchange membrane prepared in Comparative Example 2 by using a spin coating method. Spin coating was performed for 30 seconds at 500 rpm.

The mixed solution was added to 5% by weight of polypyrrole as a solid content in acetonitrile solvent, and the graphene oxide (Graphene oxide, GO) was added to the content as shown in Table 1 to the experiment to optimize the coating solution conditions. In order to reduce GO, pyrrole was used as a reducing agent at 5% by weight, and a coating solution was prepared through 30 minutes sonication after 10 hours of reaction in a 90 ° C. dry oven.

Thereafter, it was impregnated with 0.5 M FeCl ₃ aqueous solution for 30 minutes. Then, it was impregnated with 0.5 M HCl aqueous solution for 3 hours by acid treatment. Thereafter, the membrane was washed with distilled water and then impregnated in 0.5 M NaCl and stored.

Table 1 below compares the properties of the commercial membrane (AMX, Astom, Japan) and the anion exchange membrane of Comparative Example 2 and Examples 1 to 5.

Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Membrane AMX
(AstomCorp.) PFAEMW9 (VTAC1
/ STY1) PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 1 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 2 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 3 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 4 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 5 wt% rGO WU
(%) 22.1 11.89 10.20 10.31 10.52 10.23 10.22 IEC
(meq./g) 1.48 2.12 2.04 2.06 2.06 2.04 2.08 Thickness
(μm) 140 9 9 9 9 9 9 Electrical
resistance
(Cm, cm ² ) 2.47 0.181 0.291 0.317 0.344 0.355 0.425 Transport
no. 0.980 0.989 0.989 0.987 0.988 0.989 0.988

1) Water uptake (WU)

2) Ion-exchange capacity (IEC)

3) Membrane conductivity obtained by 2-point probe impedance measurement (in 0.5 M NaCl)

The anion exchange membranes of Examples 1 to 5 showed higher ion exchange capacity and lower electrical resistance than commercial membranes of Comparative Example 1, and also showed that ion transport water was equivalent to that of commercial membranes. The low electrical resistance of 1/10 of that of commercial membranes is mainly due to the thin thickness, which means that the power consumption can be greatly reduced by reducing the stack resistance in reverse electrodialysis applications.

Compared with Comparative Example 2, it was confirmed that the water content and ion exchange capacity, which are basic membrane properties, were slightly decreased, and the membrane resistance was increased, but the ion mobility was maintained the same. In addition, Examples 1 to 5 introduced PPY having a compact structure on the surface of the membrane to selectively move monovalent ions having relatively small ions. In addition, by introducing a reduced graphene oxide having a hydrophobic characteristic to the surface of the membrane to control the hydrophobicity of the surface through which it is possible to obtain the effect of excluding divalent ions having a larger hydration radius than monovalent ions. On the other hand, the selective permeability to monovalent ions can be further increased by causing greater electrostatic repulsion to divalent ions due to the -COO- functionality present in the reduced graphene oxide. In conclusion, when compared with Comparative Example 2, the performance of the process may be improved by increasing the selectivity for monovalent ions.

Comparative Example 3

Commercial membranes (CMX, Astom, Japan) of cation exchange membranes were used.

Comparative Example 4 Preparation of Cation Exchange Membrane

The porous substrate (9 μm, W-SCOPE Korea, prototype) was washed in acetone solvent for 3 hours and dried in an oven.

Subsequently, the washed porous substrate was impregnated into the monomer solution to fill the pores with monomers, and after lamination with two release films, a pore-filled cation exchange membrane was prepared by irradiating with a 1 KW UV lamp for 5 minutes.

The monomer solution is a cross-linkable monomer, an acrylic oligomer (Shin Nakamura Chemical Co., Japan, A-1000, Poly (ethylene glycol) diacrylate Mn = 2500) and a monomer having a base 2-acrylamido-2-methylpropane- Sulphonic acid (2-Acrylamido-3methylpropanesulfonic acid (AMSA)) was used in a 1: 2 molar ratio, and 80 wt% of the total polymer weight was used. At this time, the monomer having a base was dissolved and distilled water and dimethylformamide (DMF) were mixed in a ratio of 1: 4.5 by weight as a co-solvent to dissolve the A-1000 oligomer. 3 was added. Trimethylolpropane triacrylate (TMPT) was used as a crosslinking agent, and 20 wt% of the total polymer weight was used. (Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide) was used as an initiator and 5 parts by weight based on the total monomer weight was used.

Examples 6 to 10 Preparation of Cation Exchange Membrane

The mixed solution containing the conductive resin and graphene oxide was coated on the pore-filled cation exchange membrane prepared in Comparative Example 4 by using a spin coating method. Spin coating was performed for 30 seconds at 500 rpm.

The mixed solution was added 7% by weight of polypyrrole as a solid content in acetonitrile solvent, and the graphene oxide (Graphene oxide, GO) was added to the content as shown in Table 1 to the experiment to optimize the coating solution conditions. In order to reduce GO, pyrrole was used as a reducing agent at 7% by weight, and a coating solution was prepared through 30 minutes sonication after 10 hours of reaction in a 90 ° C. dry oven.

Thereafter, it was impregnated with 0.5 M FeCl ₃ aqueous solution for 30 minutes. Then, it was impregnated with 0.5 M HCl aqueous solution for 3 hours by acid treatment. Thereafter, the membrane was washed with distilled water and then impregnated in 0.5 M NaCl and stored.

Table 2 below compares the properties of the commercial membranes (CMX, Astom, Japan) and the anion exchange membrane of Comparative Example 4 and Examples 6 to 10.

Comparative Example 3 Comparative Example 4 Example 6 Example 7 Example 8 Example 9 Example 10 Membrane CMX
Astom
Corp.) PFCEMW9 (AMSA1
A-1000 0.5) PFCEMW9 (AMSA1
A-1000 0.5)
+ Modification with 7 wt% Ppy / GO 1 wt% PFCEMW9 (AMSA1
A-1000 0.5)
+ Modification with 7 wt% Ppy / GO 2 wt% PFCEMW9 (AMSA1
A-1000 0.5)
+ Modification with 7 wt% Ppy / GO 3 wt% PFCEMW9 (AMSA1
A-1000 0.5)
+ Modification with 7 wt% Ppy / GO 4 wt% PFCEMW9 (AMSA1
A-1000 0.5)
+ Modification with 7 wt% Ppy / GO 5 wt% WU
(%) 24.04 12.89 12.12 11.22 11.13 12.01 11.98 IEC
(meq./g) 1.42 1.78 1.77 1.75 1.73 1.73 1.70 Thickness
(μm) 140 9 9 9 9 9 9 Electrical
resistance
(Cm, cm ² ) 2.89 0.211 0.308 0.312 0.316 0.322 0.332 Transport no. 0.980 0.978 0.982 0.985 0.985 0.986 0.987

Compared with Comparative Example 4, Examples 6 to 10 introduced monovalent ion selectivity through surface modification to increase the membrane resistance, but the membrane resistance was lower than that of the commercial membrane and the ion migration number was increased. As described above, in Examples 6 to 10, the performance of the process may be improved by increasing the selectivity to monovalent ions as compared with Comparative Example 4.

[Water contact angle measurement]

In order to confirm the hydrophilicity of the surface of the surface-modified monovalent ion-selective pore-filled ion exchange membrane, water droplets were dropped to confirm the water contact angle.

Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Membrane AMX
(AstomCorp.) PFAEMW9 (VTAC1
/ STY1) PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 1 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 2 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 3 wt% rGO PFAEMW9 (VTAC1 / STY1)
+ Modification with 5 wt% Ppy
/ 4 wt% rGO Water contact angle (°) 54.14 60.88 71.98 73.34 77.11 79.35

Monovalent Ion Selectivity Experiment

Monovalent ion selectivity was experimented with a 4-compartment stack using two titanium electrodes coated with platinum. 0.1 M Na ₂ SO ₄ was used as the electrode solution. In the experiment of monovalent ion selectivity of the anion exchange membrane, 0.01 M NaCl / Na ₂ SO ₄ was used as the mixed solution in the dilution chamber, and distilled water was used to supply the current with constant current. The monovalent ion selectivity coefficient was calculated by ion analysis. In the monovalent ion selectivity experiment of the cation exchange membrane, the electrode solution was used in the same manner as the anion exchange membrane experiment. The mixed solution of the dilution chamber was 0.01 M Na ₂ SO ₄ / MgSO ₄ , and distilled water was used in the concentration chamber. Likewise, the monovalent ion selectivity coefficient was calculated by ion analysis by applying current with constant current and sampling the solution in the concentration chamber.

In connection with the monovalent ion selectivity experiment, the measurement method is illustrated in FIGS. 1 and 2. Table 4 was measured from FIG. 1, and Table 5 was measured from FIG.

In addition, the monovalent selectivity / membrane resistance ratio for monovalent ion selectivity, electrical resistance, and membrane resistance of the anion exchange membrane are shown in Table 4 below. Monovalent selectivity / membrane resistance ratios for electrical resistance and membrane resistance are shown in Table 5 below.

Membrane Monovalent selectivity Electrical resistance
(Cm, cm ² ) Monovalent selectivity / membrane resistance ratio Comparative Example 1 AMX 1.40 2.47 0.566802 Comparative Example 2 None 1.34 0.181 7.403315 Example 1 Ppy5.0 / rGO1.0 2.87 0.291 9.862543 Example 2 Ppy5.0 / rGO2.0 3.12 0.317 9.842271 Example 3 Ppy5.0 / rGO3.0 3.79 0.344 11.01744 Example 4 Ppy5.0 / rGO4.0 4.86 0.355 13.69014 Example 5  Ppy5.0 / rGO5.0 4.92 0.425 11.57647

Membrane Monovalent selectivity Monovalent selectivity / membrane resistance ratio Comparative Example 3 CMX (AstomCorp.) 1.12 0.388 Comparative Example 4 PFCEM W9
(AMSA1 / A-1000 0.5) 1.06 5.024 Example 6 PFCEM W9
(AMSA1 / A-1000 0.5)
+ Modification with 7 wt% Ppy /
GO 1 wt% 1.42 4.610 Example 7 PFCEM W9
(AMSA1 / A-1000 0.5)
+ Modification with 7 wt% Ppy /
GO 2 wt% 1.44 4.615 Example 8 PFCEM W9
(AMSA1 / A-1000 0.5)
+ Modification with 7 wt% Ppy /
GO 3 wt% 1.46 4.620 Example 9 PFCEM W9
(AMSA1 / A-1000 0.5)
+ Modification with 7 wt% Ppy /
GO 4 wt% 1.49 4.627 Example 10 PFCEM W9
(AMSA1 / A-1000 0.5)
+ Modification with 7 wt% Ppy /
GO 5 wt% 1.53 4.608

As shown in Tables 4 and 5, Examples 1 to 10 according to the present invention has a very high monovalent selectivity, in particular, Comparative Example 2 is not formed a modified layer comprising a conductive resin and reduced graphene particles When compared with 4, it was confirmed that monovalent ion selectivity is improved by 30% or more.

Therefore, the higher the ratio of monovalent ion selectivity to membrane resistance, the lower the resistance and the higher the monovalent ion selectivity, which means that the process performance is improved. That is, when using a membrane having high monovalent ion selectivity and low membrane resistance, power consumption may be reduced and monovalent ion selectivity may be increased, thereby increasing productivity.

In the present invention as described above has been described by specific embodiments and limited embodiments and drawings, but this is provided only to help a more general understanding of the present invention, the present invention is not limited to the above embodiments, the present invention Those skilled in the art can make various modifications and variations from this description.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later belong to the scope of the present invention. .

Claims (11)

It includes a modified layer containing a conductive resin and reduced graphene particles on the surface of the pore-filled ion exchange membrane,
The monovalent ion selectivity of the ion exchange membrane which does not include the modifying layer is M1, and the monovalent ion selectivity of the ion exchange membrane including the modifying layer is M2. This improved ion exchange membrane.
[Relationship 1]
30% ≤ (M2-M1) / M1 × 100 ≤ 300% The method of claim 1,
The pore filling ion exchange membrane is an ion exchange membrane is coated with an ion exchange resin on the surface and pores of the porous substrate. The method of claim 2,
The pore-filled ion exchange membrane is an ion exchange membrane prepared by immersing and curing a porous substrate in a mixed solution containing a crosslinkable monomer, a cation exchange group or a monomer having a base containing an anion exchange group, a co-solvent, a crosslinking agent and an initiator. The method of claim 2,
The porous substrate is an ion exchange membrane of a porous film or nonwoven fabric of a polyolefin-based material. The method of claim 1,
The conductive resin is polypyrrole ion exchange membrane. The method of claim 1,
The modified layer is an ion exchange membrane that comprises a weight ratio of conductive resin: reduced graphene particles 1: 0.1 to 1 by weight. The method of claim 1,
The ion exchange membrane is an ion exchange membrane having a water contact angle of 60 to 90 degrees. The method of claim 1,
The ion exchange membrane has an ion exchange capacity of 1.5 meq. / G or more ion exchange membrane. delete a) coating a mixed solution containing a conductive resin and graphene oxide on the pore-filling ion exchange membrane;
b) reducing the graphene oxide;
Including;
The monovalent ion selectivity of the ion exchange membrane which does not include the modifying layer is M1, and the monovalent ion selectivity of the ion exchange membrane including the modifying layer is M2. A method for producing this improved ion exchange membrane.
[Relationship 1]
30% ≤ (M2-M1) / M1 × 100 ≤ 300% The method of claim 10,
The pore filling ion exchange membrane
a-1) immersing or coating a porous substrate in a mixed solution comprising a crosslinkable monomer, a cation exchanger or an anion exchanger, or a monomer having a base capable of introducing, a cosolvent, a crosslinking agent and an initiator;
a-2) hardening by irradiating ultraviolet rays to the porous substrate immersed in the mixed solution;
Method for producing an ion exchange membrane to be prepared, including.

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