KR20170060342A

KR20170060342A - Water-treatment membrane, method for manufacturing thereof and water-treatment module comprising membrane

Info

Publication number: KR20170060342A
Application number: KR1020150164684A
Authority: KR
Inventors: 이영주; 박성경; 신정규; 김재홍; 송근원; 최형삼; 김예지
Original assignee: 주식회사 엘지화학
Priority date: 2015-11-24
Filing date: 2015-11-24
Publication date: 2017-06-01

Abstract

The present invention relates to a water treatment module including a water treatment membrane, a method for producing the same, and a water treatment membrane.

Description

TECHNICAL FIELD [0001] The present invention relates to a water treatment module including a water treatment membrane, a method for producing the same, and a water treatment membrane. [0002]

Due to the serious pollution and water shortage in recent years, it is urgent to develop new water resources. Studies on the pollution of water quality are aiming at the treatment of high quality living and industrial water, various domestic sewage and industrial wastewater, and interest in the water treatment process using the separation membrane having the advantage of energy saving is increasing. In addition, the accelerated enforcement of environmental regulations is expected to accelerate the activation of membrane technology. Conventional water treatment process is difficult to meet the regulations that are strengthened, but membrane technology is expected to become a leading technology in the water treatment field because it guarantees excellent treatment efficiency and stable treatment.

Liquid separation is classified into micro filtration, ultrafiltration, nano filtration, reverse osmosis, sedimentation, active transport and electrodialysis depending on the pores of the membrane. Among them, the reverse osmosis method refers to a process of desalting using a semi-permeable membrane which is permeable to water but impermeable to salt. When high-pressure water containing salt is introduced into one side of the semipermeable membrane, Will come out on the other side with low pressure.

In recent years, approximately 1 billion gal / day of water has been subjected to dechlorination through the reverse osmosis process. Since the first reverse osmosis process using the reverse osmosis in the 1930s was announced, many of the semi- Research was conducted. Among them, cellulose-based asymmetric membranes and polyamide-based composite membranes have become mainstream in commercial success. The cellulosic membranes developed at the beginning of the reverse osmosis membrane have various drawbacks such as narrow operating pH range, high temperature deformation, high cost of operation due to high pressure, and vulnerability to microorganisms Is a rarely used trend.

On the other hand, the polyamide composite membrane is formed by forming a polysulfone layer on a nonwoven fabric to form a microporous support, and immersing the microporous support in an aqueous solution of m-phenylenediamine (hereinafter referred to as mPD) to form an mPD layer And then the resultant is immersed or coated in an organic solution of triMesoyl Chloride (hereinafter referred to as TMC) to form a polyamide active layer by interfacial polymerization with the mPD layer in contact with TMC. By contacting the nonpolar solution with the polar solution, the polymerization takes place at the interface only and forms a very thin polyamide layer. The polyamide-based composite membrane has higher stability against pH change, can operate at lower pressure, and has a higher salt removal rate than conventional cellulose-based asymmetric membranes, and is currently a mainstream of water treatment membranes.

Studies are continuing to improve the performance of such polyamide-based composite membranes.

Korean Patent Publication No. 10-1999-0019008

The present specification is intended to provide a water treatment module including a water treatment membrane, a method for producing the same, and a water treatment membrane.

An embodiment of the present disclosure includes a porous support; A polyamide active layer provided on the porous support; And an organic polymer hardening layer provided on the polyamide active layer, wherein the organic polymer hardening layer comprises a moisturizing agent containing at least three functional groups capable of hydrogen bonding with water.

An embodiment of the present invention provides a method of manufacturing the water treatment separation membrane.

One embodiment of the present disclosure relates to a method for fabricating a porous structure, comprising: preparing a structure including a polyamide active layer provided on a porous support; And a step of coating on the polyamide active layer an organic composition comprising an organic polymer and a humectant containing at least three functional groups capable of hydrogen bonding with water and then curing to form an organic polymer cured layer .

One embodiment of the present disclosure provides a water treatment module comprising at least one water treatment separation membrane.

The water treatment separator according to one embodiment of the present invention minimizes the decrease of the permeation flow rate and can enhance the durability of the polyamide active layer. Specifically, the water treatment separation membrane according to one embodiment of the present invention can minimize the decrease in the permeation flow rate by the moisturizing agent even when the organic polymer hardening layer is provided.

The water treatment separation membrane according to one embodiment of the present invention can prevent pore shrinkage or water content lowering of the polyamide active layer due to the organic polymer hardened layer.

The water treatment separator according to one embodiment of the present invention has excellent scratch resistance by the organic polymer hardened layer.

The water treatment separation membrane according to one embodiment of the present invention has an advantage of excellent stain resistance due to a uniform surface.

1 shows a water treatment separator according to an embodiment of the present invention.

When a member is referred to herein as being "on " another member, it includes not only a member in contact with another member but also another member between the two members.

Whenever a component is referred to as "comprising ", it is to be understood that the component may include other components as well, without departing from the scope of the present invention.

In the case of a water treatment separation membrane containing a polyamide active layer, the pores of the polyamide active layer may shrink or sink due to drying of the polyamide active layer, thereby deteriorating the performance of the water treatment separation membrane. Further, the surface of the polyamide active layer can be easily damaged by physical damage such as scratches. When a protective layer is formed on the polyamide active layer to prevent this, there is a problem that the permeation flow rate of the water treatment separation membrane is lowered due to the presence of the protective layer.

The inventors of the present invention have developed a water treatment separation membrane as described below in order to solve the above problems. Specifically, the present inventors have developed a water treatment separation membrane having an organic polymer hardened layer containing a moisturizing agent on a polyamide active layer to improve the durability of the polyamide active layer and minimize the decrease in the permeation flow rate.

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

The humectant contains three or more functional groups capable of hydrogen bonding with water, and can appropriately contain moisture, thereby enhancing the water-containing ability of the organic polymer hardened layer.

According to one embodiment of the present invention, the functional group capable of hydrogen bonding may include at least one of a hydroxyl group, a carboxyl group, and an amino group.

According to one embodiment of the present invention, the humectant may be contained in the pores of the polymer matrix of the organic polymer cured layer.

The organic polymer cured layer has a polymer matrix structure, and the flow rate can be transmitted through pores according to the polymer matrix structure or by diffusion due to hydrophilicity and hydrogen bonding. However, the organic polymer cured layer is additionally provided on the polyamide active layer and may be an inhibiting factor of the permeation flow rate of the water treatment separation membrane. However, the organic polymer hardening layer includes a moisturizing agent in the pores of the polymer matrix, and through the moisture absorption effect of the moisturizing agent, it is possible to minimize a decrease in the permeation flux according to the hardened organic polymer layer.

Furthermore, the organic polymer hardened layer can prevent pore shrinkage or pore collapse due to drying of the polyamide active layer, and can improve the water content of the polyamide active layer, thereby preventing deterioration of the performance of the water treatment separator.

In addition, the organic polymer hardened layer can protect the polyamide active layer from external impact such as scratches.

Since the surface of the organic polymer hardened layer can be formed more uniform than the surface of the polyamide active layer, the organic material can be prevented from being adsorbed and contaminated.

According to one embodiment of the present invention, the humectant may include at least one of a glycerin-based compound, a glycol-based compound, and a hydrogel.

According to one embodiment of the present disclosure, the glycerin-based compound may be glycerin, polyglycerin, polyglycerin fatty acid ester, or a mixture thereof. Examples of the polyglycerin include glycerin, diglycerin, triglycerin, tetraglycerine, hexaglycerin, heptaglycerin, octaglycerin, nonaglycerin, decaglycerin and the like. The polyglycerin fatty acid ester may mean that part or all of the hydroxyl groups of the polyglycerin obtained by dehydration-polymerizing glycerin is esterified with one or more fatty acids. The polyglycerol fatty acid ester is not limited as long as it is soluble in water. For example, the polyglycerol fatty acid ester is esterified by using stearic acid, oleic acid, caprylic acid, lauric acid, myristic acid, behenic acid, erucic acid, It is possible to do. However, the present invention is not limited thereto.

According to one embodiment of the present disclosure, the glycol compound may be propylene glycol or butylene glycol. However, the present invention is not limited thereto.

According to one embodiment of the present disclosure, the hydrogel may be poly (2-hydroxyethyl-methacrylate), or poly (vinyl alcohol). However, the present invention is not limited thereto.

According to one embodiment of the present invention, the thickness of the organic polymer cured layer may be 10 nm or more and 150 nm or less.

When the thickness of the organic polymer hardened layer is within the above range, the deterioration of the performance of the water treatment separator is minimized, and the surface roughness is lowered to improve the stain resistance.

According to one embodiment of the present disclosure, the organic polymer cured layer may be a polymer matrix layer of cured polyvinyl alcohol.

In the method of manufacturing a water treatment separation membrane according to one embodiment of the present invention, the humectant, the organic polymer hardened layer, and the like may be the same as those described above.

According to one embodiment of the present disclosure, the organic polymer may be a vinyl-based polymer. Specifically, according to one embodiment of the present disclosure, the organic polymer may be polyvinyl alcohol. The polyvinyl alcohol may be polyvinyl alcohol having various molecular weights and degree of saponification.

According to one embodiment of the present invention, the weight average molecular weight of the polyvinyl alcohol may be 10,000 or more and 150,000 or less. Specifically, according to one embodiment of the present invention, the weight average molecular weight of the polyvinyl alcohol may be 120,000 or more and 140,000 or less.

According to one embodiment of the present invention, the saponification degree of the polyvinyl alcohol may be 85% or more and 99% or less. Specifically, according to one embodiment of the present invention, the degree of saponification of the polyvinyl alcohol may be 85% or more and 90% or less.

According to one embodiment of the present disclosure, the organic composition may further comprise a curing agent comprising a polyfunctional aldehyde. Specifically, the polyfunctional aldehyde may mean having at least two functional groups in one molecule. The curing agent may be at least one or more of glyoxal and glutaraldehyde.

The curing agent may serve to crosslink the organic polymer. Specifically, the organic polymer may be crosslinked by thermal curing or photo-curing in the presence of the curing agent to form an organic polymer cured layer.

According to one embodiment of the present invention, the content of the curing agent may be 1/50 or more to 1/5 or less of the content of the organic polymer.

When the content of the curing agent is within the above range, heating for curing of the organic polymer can be minimized, and deterioration of the performance of the water treatment separation membrane can be prevented. When the content of the above-mentioned scouring agent is within the above-mentioned range, the residual amount of the curing agent in the organic polymer cured layer after curing of the organic polymer is minimized, and deterioration of the performance of the water treatment separation membrane can be prevented.

According to one embodiment of the present disclosure, the organic composition may further comprise an acid catalyst.

The acid catalyst may serve to accelerate crosslinking of the organic polymer of the curing agent. Specifically, in the presence of the acid catalyst, the curing agent can crosslink the organic polymer at a higher rate. The acid catalyst may be an organic acid, an inorganic acid, or the like. Specifically, maleic acid, camphorsulfonic acid, hydrochloric acid, or the like may be used.

According to one embodiment of the present invention, the content of the acid catalyst may be 1/50 or more to 1 or less than the content of the curing agent.

When the content of the acid catalyst is within the above range, the activity of the curing agent can be maximized.

According to one embodiment of the present disclosure, the organic composition may comprise a water-soluble solvent as a solvent. Specifically, the organic composition may further comprise water or an alcohol solvent. More specifically, the organic composition may comprise water as the main solvent. In addition, the organic composition may contain water as a main solvent and may further contain 0.1 wt% or more and 5 wt% or less of alcohol.

According to one embodiment of the present invention, the content of the organic polymer may be 0.5 wt% or more and 5 wt% or less with respect to the organic composition.

According to one embodiment of the present invention, the content of the humectant may be 1 wt% or more and 30 wt% or less with respect to the organic composition.

When the content of the humectant is within the above range, the water content of the organic polymer hardened layer can be sufficiently increased, and deterioration of the performance of the water treatment separation membrane due to swelling and free volume can be prevented.

1 shows a water treatment separator according to an embodiment of the present invention. 1 illustrates a water treatment separation membrane sequentially provided with a nonwoven fabric 100, a porous support 200, a polyimide active layer 300 and an organic polymer cured layer 350. The organic polymer cured layer 350 The purified water 500 is discharged through the nonwoven fabric 100 and the concentrated water 600 is discharged to the outside without passing through the polyamide active layer 300. However, the water treatment separation membrane according to one embodiment of the present invention is not limited to the structure of FIG. 1, and further constitution may be further included.

According to one embodiment of the present invention, the porous support may be formed with a coating layer of a polymer material on a nonwoven fabric. Examples of the polymeric material include polymeric materials such as polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetheretherketone, polypropylene, polymethylpentene, polymethyl chloride and polyvinylidene fluoride Rides, and the like may be used, but the present invention is not limited thereto. Specifically, polysulfone may be used as the polymer material.

According to one embodiment of the present invention, the polyamide active layer can be formed through an interfacial polymerization of an aqueous solution containing an amine compound and an organic solution containing an acyl halide compound. Specifically, the polyamide active layer is formed by forming an aqueous solution layer containing an amine compound on a porous support; And contacting the organic solvent containing an organic solvent with an acyl halide compound on an aqueous solution layer containing the amine compound to form a polyamide active layer.

When the aqueous solution containing the amine compound is brought into contact with the organic solution, the amine compound coated on the surface of the porous support reacts with the acyl halide compound to form polyamide by interfacial polymerization, and adsorbed on the microporous support, . In the contact method, a polyamide active layer may be formed by a method such as dipping, spraying, or coating.

According to one embodiment of the present invention, a method of forming an aqueous solution layer containing an amine compound on the porous support is not particularly limited, and any method can be used as long as it is capable of forming an aqueous solution layer on a support. Specifically, a method of forming an aqueous solution layer containing an amine compound on the porous support includes spraying, coating, dipping, dropping, and the like.

At this time, the aqueous solution layer may be further subjected to a step of removing an aqueous solution containing an excess of the amine compound, if necessary. The aqueous solution layer formed on the porous support may be unevenly distributed when the aqueous solution present on the support is excessively large. If the aqueous solution is unevenly distributed, a non-uniform polyamide active layer may be formed by subsequent interfacial polymerization have. Therefore, it is preferable to remove the excess aqueous solution after forming the aqueous solution layer on the support. The removal of the excess aqueous solution is not particularly limited, but can be performed using, for example, a sponge, an air knife, nitrogen gas blowing, natural drying, or a compression roll.

According to one embodiment of the present invention, in the aqueous solution containing the amine compound, the amine compound is not limited as long as it is an amine compound used in the preparation of a water treatment separation membrane, but specific examples include m-phenylenediamine, p - phenylenediamine, 1,3,6-benzenetriamine, 4-chloro-1,3-phenylenediamine, 6-chloro-1,3-phenylenediamine, 3- Or a mixture thereof.

According to one embodiment of the present disclosure, the acyl halide compounds include, but are not limited to, for example, aromatic compounds having 2 to 3 carboxylic acid halides, such as trimethoyl chloride, isophthaloyl chlorides, Terephthaloyl chloride, and mixtures of at least one compound selected from the group consisting of terephthaloyl chloride.

According to one embodiment of the present invention, the organic solvent may be an aliphatic hydrocarbon solvent, for example, a hydrophobic liquid such as Freons and a water-immiscible hydrophobic liquid such as hexane, cyclohexane, heptane or alkane having 5 to 12 carbon atoms, An alkane having 5 to 12 carbon atoms and mixtures thereof such as IsoPar (Exxon), ISOL-C (SK Chem), and ISOL-G (Exxon) may be used.

According to one embodiment of the present invention, the water treatment separation membrane can be used as a microfiltration membrane, an ultrafiltration membrane, a nano filtration membrane or a reverse osmosis membrane, Can be used.

In addition, one embodiment of the present disclosure provides a water treatment module comprising at least one water treatment separation membrane. According to one embodiment of the present disclosure, the water treatment module may include at least one water treatment separation membrane.

The specific type of the water treatment module is not particularly limited, and examples thereof include a plate & frame module, a tubular module, a hollow & fiber module, or a spiral wound module. In addition, as long as the water treatment module includes the water treatment separation membrane according to one embodiment of the present invention, other structures and manufacturing methods are not particularly limited and general means known in the art can be employed without limitation have.

On the other hand, the water treatment module according to one embodiment of the present invention has excellent salt removal rate and permeation flow rate, and is excellent in chemical stability, and thus can be used for water treatment devices such as household / industrial water purification devices, sewage treatment devices, have.

Hereinafter, the present invention will be described in detail by way of examples with reference to the drawings. However, the embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the embodiments described below. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

[ Comparative Example One]

A structure having a polyamide active layer having a thickness of 100 nm to 200 nm formed on a porous polysulfone support was washed with deionized water and used as a water treatment separator.

[ Comparative Example 2]

A structure having a polyamide active layer with a thickness of 100 nm to 200 nm formed on a porous polysulfone support was washed with deionized water. Then, the organic polymer cured layer was immersed in the polyamide active layer in an aqueous solution containing about 1 wt% of polyvinyl alcohol, 0.01 wt% of glutaraldehyde as a curing agent and 0.01 wt% of maleic acid as an acid catalyst, To form a water treatment separation membrane.

[ Example One]

A structure having a polyamide active layer with a thickness of 100 nm to 200 nm formed on a porous polysulfone support was washed with deionized water. Then, an organic composition which is an aqueous solution containing 1 wt% of polyvinyl alcohol, 0.01 wt% of glutaraldehyde as a curing agent, 0.01 wt% of maleic acid as an acid catalyst and 2 wt% of glycerin as a wetting agent was applied onto the polyamide active layer, A polymer cured layer was formed to a thickness of about 100 nm to prepare a water treatment separation membrane.

In order to measure the salt rejection and permeate flow rate (gfd; gallon / ft ² · day) of the water treatment membranes prepared according to the above Examples and Comparative Examples, a plate type permeation cell, a high pressure pump, a reservoir and a cooling device were included And a water treatment module composed of The planar transmissive cell had a cross-flow structure with an effective permeable area of 28 cm 2. After the reverse osmosis membrane was installed in the permeable cell, the preliminary operation was performed for about 1 hour using the third distilled water to stabilize the evaluation equipment. Thereafter, the equipment was operated at a flow rate of 225 psi and 4.5 L / min in an aqueous solution of 2000 ppm sodium chloride for 1 hour to confirm that it stabilized, and then the amount of water permeated at 25 ° C for 10 minutes was measured to calculate the flux , And the salt rejection rate was calculated by analyzing the salt concentration before and after the permeation using a conductivity meter. The results are shown in Table 1 below.

Further, in order to measure the durability of the water treatment membrane, the surface of the water treatment membrane was scratched once with a Mayer bar (# 50 wired bar) at a rate of 30 mm / s, and then the salt removal rate and permeate flow rate were measured . This can be a measure for measuring the physical durability of the water treatment membrane, which is a method for determining the resistance to scratches and damage that may occur during the manufacturing process of the water treatment membrane. The results are shown in Table 1 below.

In order to measure the stain resistance of the water treatment separation membrane, salt removal rate and permeate flow rate were measured at a pressure of 225 psi after 6 hours from the addition of 2,000 ppm NaCl and 100 ppm albumin mixed solution. The results are shown in Table 1 below.

Initial Performance Performance after physical durability test Performance after pollution test Salt removal rate
(%) Permeate flow rate
(gfd) Salt removal rate
(%) Permeate flow rate
(gfd) Salt removal rate
(%) Permeate flow rate
(gfd) Comparative Example 1 99.52 24 99.23 27.4 99.68 18.9 Comparative Example 2 99.58 20.8 99.53 21.2 99.66 18.4 Example 1 99.55 23.9 99.56 23.2 99.64 21

According to Table 1, in Comparative Example 1 in which the organic polymer hardened layer was not formed, it was found that the salt removal rate greatly decreased after the physical durability test. It can be considered that the performance of the water treatment separator is deteriorated due to the damage of the polyamide active layer. On the contrary, in the case of Example 1 in which the organic polymer hardened layer was formed, the decrease in the salt removal rate after the physical durability test did not occur.

In the case of Comparative Example 1, contaminants are deposited on the surface of the active layer after the contamination test, and the permeation flow rate is rapidly lowered. On the other hand, in the case of Example 1, it can be seen that the decrease in the permeation flow rate is small even after the contamination test.

In addition, although the organic polymer hardened layer is formed, the initial permeation flow rate of Comparative Example 2, which does not include a humectant, is significantly lower than that of Example 1. It can be seen that in Example 1, the moisture-retaining agent in the organic polymer cured layer improves the moisture permeability of the organic polymer cured layer.

100: Nonwoven fabric
200: Porous support
300: polyamide active layer
350: organic polymer hardening layer
400: brine
500: Purified water
600: concentrated water

Claims

A porous support; A polyamide active layer provided on the porous support; And an organic polymer cured layer provided on the polyamide active layer,
Wherein the organic polymer hardened layer comprises a moisturizing agent containing at least three functional groups capable of hydrogen bonding with water.

The method according to claim 1,
Wherein the functional group capable of hydrogen bonding comprises at least one of a hydroxyl group, a carboxy group and an amino group.

The method according to claim 1,
Wherein the humectant is contained in the pores of the polymer matrix of the organic polymer cured layer.

The method according to claim 1,
Wherein the moisturizing agent comprises at least one or more of a glycerin-based compound, a glycol-based compound, and a hydrogel.

The method according to claim 1,
Wherein the thickness of the organic polymer hardened layer is 10 nm or more and 150 nm or less.

The method according to claim 1,
Wherein the organic polymer curing layer is a polymer matrix layer of cured polyvinyl alcohol.

Preparing a structure comprising a polyamide active layer provided on a porous support; And
Applying an organic composition comprising an organic polymer and a humectant containing at least three functional groups capable of hydrogen bonding with water on the polyamide active layer and then curing the organic composition to form an organic polymer cured layer.

The method of claim 7,
Wherein the organic composition further comprises a curing agent comprising a polyfunctional aldehyde.

The method of claim 7,
Wherein the organic composition further comprises an acid catalyst.

The method of claim 7,
Wherein the content of the organic polymer is 0.5 wt% or more and 5 wt% or less with respect to the organic composition.

The method of claim 7,
Wherein the organic polymer is polyvinyl alcohol.

The method of claim 7,
Wherein the content of the humectant is 1 wt% or more and 30 wt% or less with respect to the organic composition.

The method of claim 7,
Wherein the polyamide active layer is formed using an interfacial polymerization of an aqueous solution containing an amine compound and an organic solution containing an acyl halide compound.

A water treatment module comprising at least one water treatment membrane according to claim 1.