KR102494700B1 - Composite separation membrane for desalination and preparation method therof - Google Patents

Abstract

The present invention provides a method for manufacturing a composite separator for seawater desalination, including the steps of: (a) forming a single-layered polymer nano-thin film having a nano-wrinkle structure on the surface of a membrane; (b) forming a multi-layered thin film in which nanochannels are formed by stacking the polymer nano-thin film by repeating the polymer nano-thin film forming step; and (c) irradiating the multi-layered thin film with UV light.

Description

Composite separation membrane for desalination and preparation method therof}

The present invention relates to a composite separator for seawater desalination and a manufacturing method thereof.

Due to severe pollution and water shortage in the water quality environment, developing new water resource sources has emerged as an urgent task. Since 97% of the water on earth is seawater, seawater desalination technology that produces fresh water using abundant seawater is in the spotlight. In particular, seawater desalination technology using a thin film composite (TFC) separation membrane is the most widely used commercially because it has superior performance and stability to separation membranes of other structures.

In general, thin film composite separators are composed of a porous support layer that provides mechanical stability and a semi-permeable selective layer that determines the performance of the separator, and characteristics such as density, thickness, and surface roughness of the selective layer determine the final separation performance of the separator.

However, since the selective layer of the conventional thin film composite separator has a very high density and is thick, a very high pressure is required to desalinate seawater and a large amount of energy is consumed. In order to solve this problem, research is being conducted to improve water permeability even at low pressure by adjusting the density or thickness of the selective layer. However, water permeability and salt rejection are in a trade-off relationship with each other, and this attempt has a limit in that salt rejection is reduced even if the water permeability of the separation membrane is improved. In addition, conventional thin film composite separators have low durability due to increased contamination of the separator due to the very rough surface roughness of the thin film, but it is very difficult to perfectly control the roughness and form a thin film without defects.

That is, it is necessary to develop a composite separation membrane for seawater desalination that can simultaneously realize excellent water permeability and salt rejection and has excellent resistance to contamination.

Republic of Korea Patent No. 10-1804026

One aspect of the present invention is to provide a method for manufacturing a composite separator for seawater desalination having excellent water permeability and salt rejection.

One aspect of the present invention is to provide a composite separator for seawater desalination having excellent water permeability, salt rejection and resistance to contamination.

One aspect of the present invention is to provide a seawater desalination device having excellent energy efficiency as well as excellent performance.

For the purpose described above, the present invention provides a method comprising: (a) forming a Langmuir film having a nano-wrinkled structure by adjoining a plurality of Langmuir domains; (b) transferring the Langmuir film to a membrane to form a single-layer polymer nano-thin film on the surface of the membrane; (c) repeating the formation of the polymer nano-thin film to form a multi-layered thin film in which the polymer nano-thin film is stacked; and (d) irradiating the multilayer thin film with UV.

The single-layer polymer nano-thin film according to an aspect of the present invention may have a thickness of 1 to 20 nm.

In the step (c) according to an aspect of the present invention, the step of forming the polymer nano-thin film may be repeated 2 to 50 times to form a multi-layer thin film in which 2 to 50 layers of the polymer nano-thin film are stacked to form a nanochannel. .

The thickness of the multilayer thin film according to one aspect of the present invention may be 2 to 1,000 nm.

The Langmuir domain according to an aspect of the present invention may be formed by interfacial polymerization at a solvent-air interface.

The polymer nano-thin film according to one aspect of the present invention may be polyamide.

The polymer nanothin film according to one aspect of the present invention may include a structural unit derived from an aromatic diamine and a polyfunctional acyl halide.

In addition, the present invention is a membrane; And a multi-layered thin film formed by stacking a single layer of polymer nano-thin film on the surface of the membrane two or more times, wherein each layer of the multi-layered thin film has a nano-wrinkled structure, Provided is a composite separator for seawater desalination.

The polymer nano-thin film according to an aspect of the present invention may have a thickness of 1 to 20 nm.

The multilayer thin film according to one aspect of the present invention may be formed by stacking 2 to 50 polymer thin films.

The thickness of the multilayer thin film according to one aspect of the present invention may be 2 to 1,000 nm.

The multilayer thin film according to an aspect of the present invention may have nanochannels formed thereon.

The single-layer polymer nanothin film according to an aspect of the present invention may be formed by contacting a surface of the membrane with a Langmuir film formed by interfacial polymerization at a solvent-air interface.

The polymer nano-thin film according to one aspect of the present invention may be polyamide.

The polymer nanothin film according to one aspect of the present invention may include a structural unit derived from an aromatic diamine and a polyfunctional acyl halide.

The composite separator for seawater desalination according to an aspect of the present invention has a water permeability of 0.5 L/m ² hbar or more to pure distilled water at 25° C. and 15.5 bar, and a salt removal rate of 80 to 2000 ppm Na ₂ SO ₄ aqueous solution. % or more.

The composite separation membrane for seawater desalination according to an aspect of the present invention may have a salt removal rate of 80% or more in a 2000 ppm NaCl aqueous solution at 25° C. and 15.5 bar.

The composite separator for seawater desalination according to an aspect of the present invention may have a salt removal rate of 80% or more for a 2000 ppm MgSO ₄ aqueous solution at 25° C. and 15.5 bar.

The composite separation membrane for seawater desalination according to an aspect of the present invention may have a salt removal rate of 80% or more for a 2000 ppm MgCl ₂ aqueous solution at 25° C. and 15.5 bar.

The composite separation membrane for seawater desalination according to an aspect of the present invention may have a salt removal rate of 80% or more for a 2000 ppm CaCl ₂ aqueous solution at 25° C. and 15.5 bar.

In addition, the present invention provides a seawater desalination device including the composite separator for seawater desalination.

The composite separator for seawater desalination manufactured by the manufacturing method according to one aspect of the present invention can realize excellent performance and energy efficiency at the same time. Specifically, the composite separation membrane for seawater desalination according to one aspect of the present invention can secure an excellent salt removal rate and at the same time realize significantly improved water permeability.

In addition, the composite separator for seawater desalination according to an aspect of the present invention can implement excellent water permeability while maintaining salt removal rate, so energy efficiency can be improved, and durability can be improved due to excellent resistance to contamination.

In addition, the manufacturing method of the composite separation membrane for seawater desalination according to one aspect of the present invention has a very simple process and thus has high industrial applicability.

1 is a photograph of a Langmuir-Scheffer rough.
Figure 2 is a schematic diagram of the formation process of the polyamide thin film of Example 1.
3 is a SEM measurement result of the surface of the separator according to (a) a PES membrane, (b) Comparative Example 2, and (c) Example 1.
Figure 4 is (a) Comparative Example 1 (b) AFM measurement results of the surface of the membrane according to Example 1.
5 is a schematic diagram of a cross-flow reverse osmosis membrane evaluation device.
6 is an SEM measurement result of the surface of the separator according to Example 2.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, this invention may be implemented in many different forms, and is not limited to the embodiments described herein. Also, it is not intended to limit the scope of protection defined by the claims.

In addition, technical terms and scientific terms used in the description of the present invention, unless otherwise defined, have meanings commonly understood by those of ordinary skill in the art to which this invention belongs, and in the following description of the present invention Descriptions of well-known functions and configurations that may unnecessarily obscure the gist are omitted.

Unless there is a specific definition of the present invention, the fact that a certain part "includes" a certain component means that it may further include other components without excluding other components unless otherwise stated. Also, the singular forms used in the specification and appended claims may be intended to include the plural forms as well, unless the context dictates otherwise.

Unless otherwise specified in the present invention, "derived" means that at least one of the functional groups of a compound is modified, and specifically includes a form in which a reactive group and/or a leaving group of a compound are modified or left according to a reaction. can In addition, if the structures derived from different compounds are identical to each other, the structure derived from any one compound may also include cases where the structure derived from any other compound has the same structure.

Unless otherwise defined in the present invention, when a part such as a layer, film, thin film, region, plate, etc. is said to be "on" or "on" another part, this means not only when it is "directly on" the other part, but also in the middle thereof. It may also include the case where there is another part in .

In the present invention, unless otherwise specified, "polymer" includes oligomers, and includes homopolymers and copolymers, which copolymers include alternating polymers, block copolymers, random copolymers, branched copolymers, crosslinked copolymers, Or it may be one that includes all of them.

Hereinafter, the present invention will be specifically described.

In order to use a seawater desalination technology using a separation membrane for a long period of time, it is a very important task to improve not only the salt removal rate but also the water permeability of the separation membrane for seawater desalination. However, since the water permeability and salt rejection of the separation membrane are in a trade-off relationship with each other, there is a limit to simultaneously improving both.

The present inventors paid attention to a polyamide-based composite separator for seawater desalination, which includes, as a selective layer, a polyamide thin film formed through interfacial polymerization on the surface of a porous support layer. That is, the present inventors have found that the polyamide thin film has excellent salt removal rate but still lacks water permeability and durability, and the characteristics such as density, thickness and surface roughness of the polyamide thin film determine the final separation performance of the separator. recognized that it would. In order to solve this problem, improvement means for minimizing the thickness of the thin film and controlling the surface roughness of the thin film have been developed.

As a result of a lot of research to solve the above problems, the inventors of the present invention developed a means for stacking thin films having a nano-wrinkled structure, and by forming a multi-layered thin film formed by stacking thin films having a nano-wrinkled structure and a nanochannel structure, excellent results were obtained. It was found that the water permeability can be significantly improved while securing the salt removal rate. In addition, it was found that the water permeability can be more effectively improved by minimizing the thin film of each layer to a molecular level thickness and improving the surface area.

Specifically, when using a multi-layered thin film in which thin films are stacked, the salt removal rate can be significantly improved compared to using a single-layer film having the same thickness as the multi-layered thin film. It was found that the surface area can be widened and the water permeability can be improved very effectively. In addition, the present invention was completed by discovering a manufacturing method capable of easily manufacturing a composite separator having the above characteristics.

Hereinafter, each configuration of the present invention will be described in more detail. However, this is merely an example and the present invention is not limited to the specific embodiments described as examples.

One aspect of the present invention comprises (a) forming a Langmuir film having a nano-wrinkled structure by adjoining a plurality of Langmuir domains; (b) transferring the Langmuir film to a membrane to form a single-layer polymer nano-thin film on the surface of the membrane; (c) repeating the formation of the polymer nano-thin film to form a multi-layered thin film in which the polymer nano-thin film is stacked; and (d) irradiating the multilayer thin film with UV.

The seawater desalination composite membrane manufactured by the method for manufacturing a seawater desalination composite membrane according to one aspect of the present invention can realize excellent performance and energy efficiency at the same time. Specifically, by forming a multi-layered thin film in which polymer nano-thin films are laminated, remarkably excellent water permeability can be realized compared to the case of forming a single-layered film having the same thickness as the multi-layered thin film. In addition, nanochannels may be formed by stacking thin films having a nano-wrinkled structure, and excellent water permeability may be implemented while maintaining a salt removal rate.

The composite separator for seawater desalination according to one aspect of the present invention can be manufactured by the Langmuir method, for example, the Langmuir-Schaefer (LS) or Langmuir-Blodgett (LB) method. It may be possible, and it may be more preferable to prepare it by the Langmuir-Schaefer method.

Specifically, the Langmuir-Schaefer method is a method in which a monomolecular film (hereinafter referred to as a Langmuir film) formed by interfacial polymerization at the water-air interface and having a thickness of one molecule is moved and accumulated on a solid substrate one by one. More specifically, by horizontally contacting a monomolecular film (Langmuir film) maintained at a constant surface pressure in a Langmuir trough and a solid substrate, the Langmuir film formed on the water surface is transferred to a solid substrate and repeated to It is a method capable of forming a multilayer thin film. That is, the Langmuir-Shaffer method is a useful technique for forming a very thin monolayer film, and it is possible to easily manufacture a large-area film with almost no defects by appropriately adjusting the surface pressure, and a multi-layered monolayer film is uniformly deposited. There is an advantage in that it is easy to manufacture a thin film.

More specifically, the step (a) according to one aspect of the present invention includes (a-1) forming a polymer domain (hereinafter referred to as a Langmuir domain) having a thickness of one molecule in the Langmuir trough; (a-2) forming a monomolecular film (Langmuir film) having a nano-wrinkled structure by compressing the area by adjusting the spacing of the barriers installed in the trough and adjoining the plurality of Langmuir domains formed above to each other; can do.

The Langmuir domain according to an aspect of the present invention may be formed by interfacial polymerization at a water-air interface. Specifically, the interfacial polymerization may be performed by filling the Langmuir trough with an aqueous solution in which the first monomer is dissolved, and then evenly dispersing the second monomer solution on the surface of the aqueous solution. A method of dispersing the second monomer solution is not particularly limited as long as it can be used in the related art, but, for example, a precision syringe & needle, air-spray, or electric-spray (electro-spray) and the like can be used.

The polymer nanothin film according to one aspect of the present invention is not particularly limited as long as it is a polymer that can be used in the related art, but may be, for example, polyamide. Specifically, the polymer nano-thin film may be formed by interfacial polymerization of an aromatic diamine (first monomer) and a polyfunctional acyl halide (second monomer).

The aromatic diamine is not limited as long as it is a compound used in the art, but examples include m-phenylenediamine, p-phenylenediamine, 1,2,4-benzenetriamine, 4-chloro-1,3 -It may be selected from phenylenediamine, 2-chloro-1,4-phenylenediamine, or a combination thereof. It may preferably be m-phenylenediamine, but is not limited thereto.

In addition, the polyfunctional acyl halide is not limited as long as it is a compound commonly used in the art, but may be, for example, selected from trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, or a combination thereof. there is. It may be preferably trimesoyl chloride, but is not limited thereto.

In the step (a-2) according to an aspect of the present invention, the surface pressure of the water surface on which the Langmuir domains are formed can be adjusted by adjusting the barrier interval. In addition, when the Langmuir film is formed by adjusting the barrier spacing, a nano-wrinkled structure may be formed. The nano-wrinkle structure formed here is formed by surface pressure, and the nano-wrinkle structure and the nano-channel structure formed above can be effectively maintained by UV irradiation later. The surface pressure may be preferably 30 to 50 mN/m, or 30 to 40 mN/m, and more preferably 35 to 45 mN/m. By maintaining the surface pressure within the above-mentioned range, a large-area Langmuir film having almost no defects can be formed, and the thickness of the nano-wrinkle structure and the Langmuir film thickness can be appropriately adjusted. However, the surface tension is not greatly limited as long as the nano-wrinkle structure can be appropriately controlled.

That is, by using the manufacturing method according to one aspect of the present invention, the thickness of the polymer nano-thin film formed on the membrane can be adjusted in nanometer units, and the surface roughness of the polymer nano-thin film can be easily controlled. .

The membrane according to one aspect of the present invention may be used without limitation as long as it is commonly used in the corresponding field, but, for example, polysulfone, polyethersulfone, polyimide, polyamide, polyetherimide, polyacrylonite It may include one or two or more selected from reel, polymethyl methacrylate, polyethylene, polypropylene, and polyvinylidene fluoride. Preferably, polyethersulfone may be used, but is not limited thereto. In addition, the membrane may have a thickness of 1 μm to 1 cm, 1 μm to 1000 μm, or 5 μm to 500 μm, but is not limited thereto.

The average size of the pores of the membrane according to one aspect of the present invention may be 1,000 to 500,000 Molecular Weight Cut-Off (MWCO), preferably 10,000 to 20,000 Molecular Weight Cut-Off. As the membrane having the above-described pore size is used, desalinated water can easily permeate the membrane.

In one aspect of the present invention, the thickness of the single-layer polymer nano-thin film formed in step (b) is not particularly limited as long as it is nano-sized, but can be determined by the surface pressure described above, for example, 1 to 100 nm , preferably 1 to 50 nm, 1 to 20 nm, or 1 to 10 nm, and more preferably 1 to 5 nm. By forming a polymer nano-thin film that satisfies the thickness range, the water permeability of the seawater desalination composite membrane can be further improved.

In the step (c) according to an aspect of the present invention, the number of stacking polymer nano-thin films is not particularly limited, but may be, for example, 2 to 50 times, preferably 2 to 20 times. As the number of stacking is satisfied, the effect of simultaneously improving water permeability and salt rejection of the seawater desalination composite separation membrane can be more effectively improved. Specifically, nanochannels can be formed as the polymer nanofilms having nanowrinkled structures are laminated in step (c), and the nanochannel structure can further improve water permeability of the seawater desalination composite membrane.

The thickness of the multi-layered thin film according to one aspect of the present invention is not particularly limited, but may be determined according to the number of stackings, and may be, for example, 2 to 400 nm when stacked 2 to 20 times, preferably 2 to 1000 nm, 2 to 400 nm, or 2 to 250 nm, more preferably 2 to 100 nm.

In one aspect of the present invention, the step (d) may be to irradiate UV after precipitating the membrane on which the multilayer thin film is formed in water. The UV wavelength range may be 200 to 400 nm, or 250 to 400 nm, or 300 to 400 nm, and the UV irradiation time is 1 minute to 30 minutes, or 5 minutes to 20 minutes, or 10 minutes to 20 minutes. may be performed.

The composite separator for seawater desalination according to an aspect of the present invention can prevent deformation of the nano-wrinkle structure and the nano-channel structure formed above as a result of subsequent UV irradiation, and can further improve the surface area. For example, the composite separator for seawater desalination according to one aspect of the present invention may have a surface area increased by 20% or more after UV irradiation, 20 to 100%, preferably 20 to 50%, and more preferably 30 to 50% may be increasing. As the surface area is improved as described above, the water permeability of the composite separator for seawater desalination according to one embodiment of the present invention can be improved more effectively. On the other hand, in the case of post-processing through heat treatment instead of UV irradiation, the thickness and spacing of the nano-wrinkle structure increase and the surface area can be greatly reduced (FIG. 4-(a)).

The nano-wrinkle structure formed after step (d) may have a wrinkle thickness of 1 nm to 60 nm, preferably 1 nm to 40 nm, and more preferably 1 nm to 30 nm. In addition, the spacing of the wrinkles may be 1 nm to 100 nm, preferably 10 nm to 100 nm, more preferably 20 nm to 80 nm. As the wrinkle thickness and spacing of the above-mentioned values are satisfied, the surface area of the polymer nano-thin film can be significantly increased and excellent water permeability can be realized.

In addition, one aspect of the present invention is a membrane; And a multi-layered thin film formed by stacking a single layer of polymer nano-thin film on the surface of the membrane two or more times, wherein each layer of the multi-layered thin film has a nano-wrinkled structure, Provided is a composite separator for seawater desalination.

The composite separator for seawater desalination according to an aspect of the present invention has a water permeability to ultrapure water of 0.5 L/m ² hbar or more at 25° C. and 15.5 bar, and a salt removal rate of 80% for an aqueous solution of 2000 ppm Na ₂ SO ₄ may be ideal Specifically, the water permeability to ultrapure water may be 1.0 L/m ² hbar or more, and the salt removal rate for a 2000 ppm Na ₂ SO ₄ aqueous solution may be 85% or more, 90% or more, or 95% or more.

In addition, the composite separation membrane for seawater desalination according to an aspect of the present invention may have a salt removal rate of 80% or more, or 85% or more with respect to a 2000 ppm NaCl aqueous solution at 25 ° C. and 15.5 bar. The composite separator for seawater desalination may have a salt removal rate of 80% or more, 85% or more, or 90% or more for a 2000 ppm MgSO ₄ aqueous solution at 25° C. and 15.5 bar. The composite separator for seawater desalination may have a salt removal rate of 80% or more, or 85% or more for a 2000 ppm MgCl ₂ aqueous solution at 25° C. and 15.5 bar. The composite separator for seawater desalination may have a salt removal rate of 80% or more, or 85% or more, for a 2000 ppm CaCl ₂ aqueous solution at 25° C. and 15.5 bar.

In addition, one aspect of the present invention provides a seawater desalination device including a composite separator for seawater desalination. By using the composite separation membrane for seawater desalination according to one aspect of the present invention, it is possible to secure excellent salt rejection and at the same time achieve excellent water permeability. Specifically, a multi-layered thin film in which polymer nano-thin films are stacked is formed, and a remarkably excellent salt removal rate can be realized, and a nano-wrinkled structure is formed on the thin film of each layer to secure an excellent salt removal rate and realize excellent water permeability. can In addition, the manufacturing method of the composite separation membrane for seawater desalination according to one aspect of the present invention may have very high industrial applicability because the manufacturing process is simple and does not require an additional configuration.

The present invention will be described in more detail based on the following Examples and Comparative Examples. However, the following Examples and Comparative Examples are only one example for explaining the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples.

The following physical properties were measured as follows.

1) Thickness

The thickness was measured by observing a cross-sectional image by a field emission scanning electron microscope (FE-TEM).

2) Area of nano-wrinkle structure

The area of the nanowrinkle structure was measured by observing the surface image by atomic force microscopy (AFM).

3) Water permeability

Ultrapure water was used to measure the water permeability. A cross-flow type reverse osmosis membrane evaluation device (FIG. 5) was used, and sufficient preliminary operation was performed for about 24 hours with ultrapure water at 15.5 bar pressure and 25 ° C temperature conditions to stabilize the evaluation equipment. Thereafter, water permeability was calculated by measuring the amount of ultrapure water permeated for 60 minutes. At this time, the unit of water permeability is L/m ² hbar.

4) Salt removal rate

The salt removal rate was measured using a 2,000 ppm aqueous salt solution (NaCl, MgSO ₄ , MgCl ₂ , CaCl ₂ , Na ₂ SO ₄ ). A cross-flow type reverse osmosis membrane evaluation device (FIG. 5) was used, and sufficient preliminary operation was performed for about 24 hours with ultrapure water at 15.5 bar pressure and 25 ° C temperature conditions to stabilize the evaluation equipment. Thereafter, the 2,000 ppm aqueous salt solution was permeated for 5 days, and the salt removal rate (%) was calculated by comparing the salt concentration before and after permeation.

[Example 1]

Formation of polyamide thin film

The formation process of the polyamide thin film is shown in FIG. 2 . Specifically, 350 ml of a 0.1 wt% meta-phenylene diamine (MPD) aqueous solution was filled in a Langmuir-Schaefer trough (LS trough), and then the barrier was widened to the end to obtain a surface pressure value. It was set to 0 mN/m. Thereafter, 60 μl of a 0.05 wt% trimesoyl chloride (TMC) solution dispersed in hexane was taken with a precision syringe & needle and evenly sprayed on the surface of the MPD aqueous solution. After 10 minutes, the interfacial polymerization reaction between MPD and TMC was sufficiently completed at the water-air interface, and a polyamide domain (Langmuir domain) was formed on the surface of the MPD aqueous solution.

Then, the barrier was moved at a speed of 12 mm/min to compress the space so that the surface pressure value was 40 mN/m, and the polyamide domain formed on the water surface was adjoined to form a film to form a polyamide film having a nano-wrinkled structure. (Langmuir film) was formed. At this time, the dipper unit to which the PES UF (Polyethersulfone ultrafiltration, synder) membrane was attached in the horizontal direction was lowered at a rate of 5 mm/min to bring the surface of the PES UF membrane into contact with the polyamide film. After contacting for 15 seconds, the dipper unit was raised at a speed of 5 mm/min, and it was confirmed that a single-layer polyamide nano-thin film was transferred to the surface of the PES UF membrane. At this time, the thickness of the single-layer polyamide thin film was 2.3 nm.

Manufacturing of composite membrane for seawater desalination

By repeating the process of forming the polyamide thin film 5 times, a multilayer thin film in which the polyamide thin film was laminated 5 times was formed on the surface of the PES UF membrane. Thereafter, the membrane on which the multilayer thin film was formed was precipitated in water, and 365 nm UV was irradiated for 15 minutes to prepare a seawater desalination composite separator (FIG. 4-(b)). The thickness of the multilayer thin film was 9.6 nm, and the area of the nanowrinkle structure formed on the surface of the thin film was about 48.5%.

The water permeability of the composite membrane for seawater desalination of Example 1 was 1.23±0.09 L/m ² hbar, the salt removal rate for Na ₂ SO ₄ aqueous solution was 96.87±0.008 %, and the salt removal rate for MgSO ₄ aqueous solution was 94.36±0.28 , the salt removal rate for the MgCl ₂ aqueous solution was 88.71±0.24, the salt removal rate for the CaCl- ₂ aqueous solution was 87.62±0.007, and the salt removal rate for the NaCl aqueous solution was 85.04±1.97%.

[Example 2]

In Example 1, the same procedure was carried out except that the 0.05 wt% trimesoyl chloride (TMC) solution was dispersed on the water surface using an air-spray instead of a precision syringe, A composite separator for seawater desalination of 2 was prepared (FIG. 6). At this time, the thickness of the single-layer polyamide thin film was 2.3 nm, and the thickness of the multi-layer thin film laminated five times was 9.6 nm.

[Comparative Example 1]

The same procedure as in Example 1 was performed except that the step of heat treatment at 80 ° C. for 10 minutes in a vacuum oven was performed without performing the UV irradiation step after forming the multilayer thin film in which the polyamide thin film was stacked 5 times. Thus, a composite separator for seawater desalination of Comparative Example 1 was prepared (FIG. 4-(a)). The thickness of the multilayer thin film was 9.6 nm, and the area of the nanowrinkle structure formed on the surface of the thin film was about 37.4%.

The water permeability of the composite separator for seawater desalination of Comparative Example 1 was 0.41±0.04 L/m ² hbar, and the salt removal rate with respect to aqueous NaCl solution was 85.55±2.42%.

[Comparative Example 2]

The PES UF membrane was immersed in a 0.1 wt% meta-phenylene diamine (MPD) aqueous solution for 10 minutes, then taken out, and the excess MPD solution on the surface of the membrane was removed with a Teflon roller. Thereafter, 5 ml of a 0.05 wt% trimesoyl chloride (TMC) solution dispersed in hexane was poured onto the surface of the membrane, followed by interfacial polymerization for 1 minute to form a polyamide layer. Unreacted TMC was washed with hexane, and dried in a vacuum oven at 80 ° C. for 10 minutes to form a polyamide thin film having a thickness of 100 nm, thereby preparing a composite separator for seawater desalination of Comparative Example 2 (FIG. 3-b).

The water permeability of the composite separator for seawater desalination of Comparative Example 2 was 0.23±0.05 L/m ² hbar, and the salt removal rate with respect to an aqueous NaCl solution was 86.1%.

It was confirmed that the surface area of the composite separator for seawater desalination according to Example 1 of the present invention increased by about 30% compared to Comparative Example 1. That is, it can be seen that the composite separator for seawater desalination according to one aspect of the present invention can maintain the nano-wrinkle structure excellently and significantly improve the surface area by UV irradiation. Accordingly, it can be seen that the water permeability of the composite separator for seawater desalination according to Example 1 is significantly improved compared to Comparative Example 1 (Example 1: 1.23±0.09 L/m ² hbar, Comparative Example 1: 0.41±0.04 L /m ² hbar).

In addition, it can be seen that the composite separator for seawater desalination according to one aspect of the present invention can achieve very excellent water permeability while securing a salt removal rate similar to that of commercially available reverse osmosis polyamide thin film composites (DOW, SW30XLC). (Example 1: 1.23±0.09 L/m ² hbar, SW30XLC: 0.83±0.03 L/m ² hbar).

In addition, referring to FIG. 3, when compared with the thin film of Comparative Example 2 (FIG. 3-b) using the conventional interfacial polymerization method, Example 1 using the manufacturing method according to one aspect of the present invention (FIG. 3-c ) can be seen that the surface roughness is significantly improved. Accordingly, it can be seen that the composite separator for seawater desalination according to one aspect of the present invention can have improved resistance to contamination and improved durability.

That is, the composite separator for seawater desalination according to one aspect of the present invention is characterized in that a multi-layered thin film having a nano-channel structure is formed by stacking polymer nano-thin films having a nano-wrinkle structure, thereby securing excellent salt rejection. At the same time, excellent water permeability can be realized. In addition, the surface roughness of the composite separator for seawater desalination according to one aspect of the present invention is significantly improved, so that resistance to contamination can be further improved. In addition, the manufacturing method of the composite separation membrane for seawater desalination according to one aspect of the present invention may have very high industrial applicability because the manufacturing process is simple and does not require an additional configuration.

Claims (21)

(a) forming a Langmuir film having a nano-wrinkled structure by adjoining a plurality of Langmuir domains;
(b) transferring the Langmuir film to a membrane to form a single-layer polymer nano-thin film on the surface of the membrane;
(c) repeating the formation of the polymer nano-thin film to form a multi-layered thin film in which the polymer nano-thin film is stacked; and
(d) irradiating UV to the multi-layer thin film; manufacturing method of a composite separator for seawater desalination, including. According to claim 1,
The thickness of the single-layer polymer nano-thin film is 1 to 20 nm, a method for producing a composite separator for seawater desalination. According to claim 1,
In the step (c), the step of forming the polymer nano-thin film is repeated 2 to 50 times to form a multi-layered thin film in which a nano-channel is formed by stacking 2 to 50 polymer nano-thin films. method. According to claim 3,
The thickness of the multilayer thin film is 2 to 1,000 nm, a method for producing a composite separator for seawater desalination. According to claim 1,
The Langmuir domain is formed by interfacial polymerization at the solvent-air interface, a method for producing a composite separator for seawater desalination. According to claim 1,
The polymer nano-thin film is polyamide, a method for producing a composite separator for seawater desalination. According to claim 6,
The method of manufacturing a composite separator for seawater desalination, wherein the polymer nano-thin film includes a structural unit derived from an aromatic diamine and a polyfunctional acyl halide. membrane; And a multi-layer thin film formed by stacking a single layer of polymer nano-thin film on the surface of the membrane two or more times. As a composite separator for seawater desalination comprising:
The polymer nano-thin film of each layer of the multi-layer thin film is a composite separator for seawater desalination in which a nano-wrinkled structure is formed. According to claim 8,
The polymer nano-thin film has a thickness of 1 to 20 nm, a composite separator for seawater desalination. According to claim 8,
The multilayer thin film is a composite separator for seawater desalination, which is formed by stacking 2 to 50 layers of polymer thin films. According to claim 10,
The multilayer thin film has a thickness of 2 to 1,000 nm, a composite separator for seawater desalination. According to claim 8,
The multilayer thin film is a composite separator for seawater desalination, in which nanochannels are formed. According to claim 8,
The single-layer polymer nano-thin film is formed by contacting the surface of the membrane with a Langmuir film formed by interfacial polymerization at a solvent-air interface. According to claim 8,
The polymer nano-thin film is a polyamide composite membrane for seawater desalination. According to claim 8,
The polymer nano-thin film includes a structural unit derived from an aromatic diamine and a polyfunctional acyl halide, a composite separator for seawater desalination. According to claim 8,
The composite membrane for seawater desalination has a water permeability of 0.5 L/m ² hbar or more to pure distilled water at 25° C. and 15.5 bar, and a salt removal rate of 80% or more for a 2000 ppm Na ₂ SO ₄ aqueous solution. separator. According to claim 16,
The composite separator for seawater desalination has a salt removal rate of 80% or more for a 2000 ppm NaCl aqueous solution at 25 ° C. and 15.5 bar. According to claim 16,
The composite separator for seawater desalination has a salt removal rate of 80% or more for a 2000 ppm MgSO ₄ aqueous solution at 25 ° C. and 15.5 bar. According to claim 16,
The composite separator for seawater desalination has a salt removal rate of 80% or more for a 2000 ppm MgCl ₂ aqueous solution at 25 ° C. and 15.5 bar. According to claim 16,
The composite separator for seawater desalination has a salt removal rate of 80% or more for a 2000 ppm CaCl ₂ aqueous solution at 25 ° C. and 15.5 bar. A seawater desalination device comprising the composite separator for seawater desalination according to any one of claims 8 to 20.

Images