KR101477848B1 - Reverse osmosis membrane having ultra hydrophilic layer and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a porous support; A polyamide active layer formed on the porous support; And a super hydrophilic layer formed on the polyamide active layer, wherein the super hydrophilic layer comprises a material represented by the following formula (1) and a method for producing the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane including an ultra-hydrophilic layer and a method of manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane, and more particularly, to a reverse osmosis membrane including a super hydrophilic layer and having excellent resistance to contamination.

The phenomenon that the solvent moves between the two solutions separated by the semi-permeable membrane through the membrane from the solution with a low solute concentration to the solution with a high solute concentration is called osmotic phenomenon. The pressure acting on the solution side Is called osmotic pressure. However, when an external pressure higher than osmotic pressure is applied, the solvent moves toward the solution having a low solute concentration. This phenomenon is called reverse osmosis. By using the reverse osmosis principle, it is possible to separate various salts or organic substances through the semipermeable membrane using the pressure gradient as a driving force. Reverse osmosis membranes using this reverse osmosis membrane are used for separating molecular-level substances and removing salts from brine or sea water to supply domestic, architectural and industrial water.

A typical example of such a reverse osmosis separator is a polyamide reverse osmosis separator. The polyamide reverse osmosis separator is manufactured by forming a polyamide active layer on a microporous layer support. More specifically, A polysulfone layer is formed on the nonwoven fabric to form a microporous support. The microporous support is immersed in an aqueous solution of m-Phenylene Diamine (mPD) to form an mPD layer, which is then reacted with trimethoyl chloride TriMesoyl Chloride (TMC)) in an organic solvent to form a polyamide layer by interfacial polymerization of the mPD layer in contact with TMC.

On the other hand, with recent TiO ₂ to a polyamide active layer a vinyl monomer graft-copolymerized, or (U.S. Patent 20,090,308,804), a polyamide active layer on the surface to enhance the durability and stain resistance to the polyamide layers to improve the performance of the reverse osmosis membrane, And a method of introducing the same inorganic particles (USP 6551536). However, in the case of the above techniques, the effect is insignificant or the coating layer of several layers must be formed, so that the thickness of the reverse osmosis membrane becomes thick, thereby deteriorating the water purification function, and the manufacturing process is complicated.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a reverse osmosis membrane having excellent stain resistance without reducing detergency such as salt removal rate and permeation flow rate.

In one aspect, the present invention provides a porous support comprising: a porous support; A polyamide active layer formed on the porous support; And a super hydrophilic layer formed on the polyamide active layer, wherein the super hydrophilic layer comprises a material represented by the following formula (1).

[Chemical Formula 1]

Wherein x is an integer of 70 to 95 and y is an integer of 5 to 30.

At this time, the thickness of the super hydrophilic layer is preferably about 1 to 10 nm.

In another aspect, the present invention provides a process for preparing a reverse osmosis membrane, which comprises treating a porous support having a polyamide active layer formed thereon with an aqueous solution containing the superhydrophilic substance of Formula 1.

At this time, it is preferable that the aqueous solution contains 0.0001 wt% to 10 wt% of the superhydrophilic substance represented by the formula (1), and the treatment may be performed by a dipping method.

Meanwhile, the superhydrophilic substance of Formula 1 may be prepared by mixing 2-hydroxyethyl acrylate and acrylamine in an equivalent ratio of 70:30 to 95: 5, and then reacting, For 1 to 6 hours.

The reverse osmosis membrane containing the super hydrophilic layer of the present invention has excellent stain resistance compared to the conventional reverse osmosis membrane without deteriorating water purification performance.

Hereinafter, the present invention will be described more specifically.

As a result of repeated studies to develop a reverse osmosis membrane having excellent stain resistance without deteriorating water purification performance, the present inventors have found that by forming an super hydrophilic layer containing a super hydrophilic substance represented by the following Chemical Formula 1 on a polyamide active layer, The present invention has been accomplished on the basis of these findings.

The reverse osmosis membrane of the present invention comprises (1) a porous support, (2) a polyamide active layer, and (3) an super hydrophilic layer.

The porous support may be a porous support having a coating layer of a polymeric material formed on a nonwoven fabric. Examples of the polymeric material include polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, poly An ether imide, a polyether ether ketone, a polypropylene, a polymethylpentene, a polymethyl chloride, and a polyvinylidene fluoride, but is not limited thereto. Of these, polysulfone is particularly preferable.

On the other hand, (2) the polyamide active layer may be formed by an interface polymer of an amine compound and an acyl halide compound, wherein the amine compound includes, but is not limited to, m-phenylenediamine, p-phenyl 1,3-phenylenediamine, 3-chloro-1, 4-phenylenediamine, 3-chloro-1,3-phenylenediamine, . ≪ / RTI > In addition, the acyl halide compound is not limited thereto, but is preferably, for example, trimethoyl chloride, isophthaloyl chloride, terephthaloyl chloride, or a mixture thereof.

Next, the (3) super hydrophilic layer comprises a material represented by the following formula (1).

[Chemical Formula 1]

X is an integer of 70 to 95, y is an integer of 5 to 30, preferably x is an integer of 85 to 95, y is an integer of 5 to 15, and most preferably x Is an integer of 85 to 90, and y is an integer of 10 to 15.

On the other hand, the substance represented by the above formula (1) is a super hydrophilic substance having a large amount of hydroxyl and amine groups, and when the above substance is coated on the polyamide active layer, contaminants such as dust, Therefore, it has a role of improving the stain resistance of the reverse osmosis membrane

The material represented by Formula 1 may be prepared by mixing 2-hydroxyethyl acrylate and acrylamide in an equivalent ratio of 70:30 to 95: 5 and then reacting. At this time, the reaction is preferably carried out at 45 to 80 ° C for 1 to 6 hours.

On the other hand, it is preferable that the thickness of the super-hydrophilic layer including the substance represented by Formula 1 is about 1 to 10 nm. When the thickness of the super-hydrophilic layer is within the above-mentioned range, both the contamination resistance and the water purifying performance are good.

Next, a method for producing a reverse osmosis membrane of the present invention will be described.

The reverse osmosis membrane of the present invention can be produced by treating a porous support having a polyamide active layer formed thereon with an aqueous solution containing the superhydrophilic substance of Formula 1.

At this time, the method of forming the polyamide active layer on the porous support is not particularly limited and may be performed by a reverse osmosis membrane manufacturing method well known in the art. For example, the porous support is immersed in an aqueous solution of m-Phenylene Diamine (mPD) to form an mPD layer, which is then immersed in an organic solvent of TriMesoyl Chloride (TMC) The polyamide active layer can be formed by interfacial polymerization by contacting with TMC. Alternatively, the polyamide active layer may be formed by a method such as spraying or coating instead of the dipping method.

On the other hand, the step of treating the porous support on which the polyamide active layer is formed with an aqueous solution containing the superhydrophilic substance of the above formula (1) can be carried out, for example, by mixing the porous support on which the polyamide active layer is formed with the superhydrophilic Or by immersing it in an aqueous solution containing the substance. At this time, the aqueous solution preferably contains the superhydrophilic substance in an amount of 0.0001 to 10% by weight, preferably 0.0001 to 5% by weight, and most preferably 0.0001 to 1% by weight. If the concentration of the superhydrophilic substance is less than 0.0001 wt%, the coating may not be entirely coated on the polyamide active layer. If the concentration of the superhydrophilic substance is greater than 10 wt%, the coated thickness of the superhydrophilic substance may be increased, which may affect the performance of the reverse osmosis membrane.

The immersion time is preferably about 2 to 3 hours. When the immersion time is short, the super hydrophilic material does not adhere well to the polyamide active layer. If the immersion time is prolonged, it reacts between the super hydrophilic materials and aggregates them to affect the performance of the reverse osmosis membrane.

When the super hydrophilic layer is coated on the polyamide active layer through the immersion treatment, it is preferable to perform the step of drying at about 50 to 60 ° C for about 30 to 40 minutes in order to improve the adhesion between the super hydrophilic layer and the polyamide active layer Do.

Meanwhile, the substance represented by the formula 1 used in the present invention can be prepared by mixing 2-hydroxyethyl acrylate and acrylamide in an equivalent ratio of 70:30 to 95: 5 and then reacting. At this time, the reaction is preferably carried out at 45 to 80 ° C for 1 to 6 hours.

Since the reverse osmosis membrane of the present invention produced by the above-described method has a superfine hydrophilic layer formed on its surface, the antifouling property against organic substances is very strong, and even in the purification function such as initial salt wager ratio and initial permeation flow rate, Or more.

Hereinafter, the present invention will be described in detail with reference to specific examples.

Manufacturing example  Preparation of Porous Support with 1-Polyamide Active Layer

18% by weight of polysulfone solid was added to DMF (N, N-dimethylformamide) solution and dissolved at 80 DEG C for 12 hours or more to obtain a uniform liquid phase. This solution was cast on a nonwoven fabric having a thickness of 95 to 100 mu m made of polyester to a thickness of 45 to 50 mu m to form a porous polysulfone support.

The porous polysulfone support prepared in the above manner was immersed in an aqueous solution containing 2% by weight of m-phenylenediamine for 2 minutes, and then the excess aqueous solution on the support was removed using a 25 psi roller and dried at room temperature for 1 minute .

Then, the support was immersed in 0.1 wt% organic solution of trimesoyl chloride using ISOL-C (SK Chem) solvent for 1 minute, and then taken out and dried in an oven at 60 ° C for 10 minutes. Thereafter, the membrane was rinsed with 0.2 wt% sodium carbonate aqueous solution at room temperature for 2 hours or more, and then washed with distilled water to prepare a porous support having a polyamide active layer with a thickness of 200 nm.

Manufacturing example  2 - Super hydrophilic  Manufacture of materials

2-hydroxyethyl acrylate and acrylamide were placed in an aqueous solution at an equivalent ratio of 9: 1 and reacted at 60 占 폚 for 3 hours to obtain the compound of formula (1).

Example  One

The porous support having the polyamide active layer prepared in Preparation Example 1 was washed with distilled water and then immersed in an aqueous solution containing 0.0001-10% by weight of the substance of the formula (1) prepared in Preparation Example 2 for 2 to 3 hours And then dried in an oven at 60 DEG C for 30 to 40 minutes to form an super hydrophilic layer.

Example  2

A super hydrophilic layer was formed in the same manner as in Example 1, except that the content of the substance of Chemical Formula 1 in the aqueous solution was changed to 0.001% by weight.

Example  3

The superfine hydrophilic layer was formed in the same manner as in Example 1, except that the content of the substance of Chemical Formula 1 in the aqueous solution was changed to 0.01 wt%.

Example  4

A super-hydrophilic layer was formed in the same manner as in Example 1, except that the content of the compound of Formula 1 in the aqueous solution was 0.1 wt%.

Example  5

A super-hydrophilic layer was formed in the same manner as in Example 1, except that the content of the substance of Chemical Formula 1 in the aqueous solution was 1 wt%.

Example  6

A super hydrophilic layer was formed in the same manner as in Example 1, except that the content of the substance of Chemical Formula 1 in the aqueous solution was changed to 10 wt%.

Comparative Example

For comparison, the porous support having the polyamide active layer prepared in Production Example 1 was washed with distilled water and used without any surface treatment.

Experimental Example  1 - integer performance evaluation

The initial salt rejection rate and the initial permeate flow rate of the reverse osmosis membrane prepared in Examples 1 to 6 and Comparative Examples were measured. The initial salt rejection rate and the initial permeate flow rate were measured while supplying 32,000 ppm aqueous sodium chloride solution at 25 ° C at a flow rate of 1400 mL / min. The reverse osmosis membrane cell device used for the evaluation of the membrane was equipped with a plate-type permeation cell, a high-pressure pump, a reservoir and a cooling device. The structure of the plate-type permeation cell was a cross-flow type with an effective permeate area of 140 cm ² . After the washed reverse osmosis membrane was installed in the permeation cell, the preliminary operation was performed for about 1 hour using third distilled water for stabilization of the evaluation equipment. Then, the apparatus was operated for about 1 hour until the pressure and permeate flow rate reached a steady state by replacing with 32,000 ppm sodium chloride aqueous solution. Then, the flow rate was calculated by measuring the amount of water permeated for 10 minutes, and the conductivity was measured with a Conductivity Meter ) Was used to calculate the salt rejection rate by analyzing the salt concentration before and after permeation. The measurement results are shown in Table 1 below.

Initial salt exclusion rate (%) Initial permeate flow (gallon / ft ² · day) Example 1 97.64 27.12 Example 2 97.98 26.63 Example 3 98.46 27.46 Example 4 98.97 27.85 Example 5 98.36 26.43 Example 6 98.07 27.28 Comparative Example 97.80 27.48

Experimental Example  2 - Evaluation of stain resistance

The stain resistance of the reverse osmosis membrane prepared in Example 4 and Comparative Example was evaluated. The stain resistance evaluation was carried out using a 32,000 ppm aqueous NaCl solution and a 100 ppm casein mixed aqueous solution. After the initial salt rejection rate and the flow rate were evaluated, a casein aqueous solution of 100 ppm was put into the evaluator tank, and the change in the salt rejection rate and the flow rate was immediately measured. Then, changes in salt excretion rate and flow rate were measured after 2 hours. Casein was dissolved in an aqueous solution having a pH of 11 or more. The measurement results are shown in Table 2.

Initial flow rate immediately after casein injection Initial flow after 2 hours of casein injection The rate of salt elimination immediately after the addition of casein 2 hours after the addition of casein, Example 4 27.56 26.98 98.69 98.71 Comparative Example 26.89 23.61 97.15 96.58

Claims (11)

A porous support;
A polyamide active layer formed on the porous support; And
And an ultra-hydrophilic layer formed on the polyamide active layer,
Wherein the super hydrophilic layer comprises a material represented by the following formula (1).

[Chemical Formula 1]

Wherein x is an integer of 70 to 95 and y is an integer of 5 to 30.
The method according to claim 1,
Wherein the super hydrophilic layer has a thickness of 1 to 10 nm.
The method according to claim 1,
The porous support may be formed on a nonwoven fabric by using a polymeric material selected from the group consisting of polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetheretherketone, polypropylene, polymethylpentene, polymethylchloride and polyvinylidene fluoride Wherein the coating layer is formed by coating at least one selected from the group consisting of the following.
The method according to claim 1,
Wherein the polyamide active layer is formed by an interface polymer of an amine compound and an acyl halide compound.
5. The method of claim 4,
The amine compound may be at least one selected from the group consisting of m-phenylenediamine, p-phenylenediamine, 1,3,6-benzenetriamine, 4-chloro-1,3-phenylenediamine, 6- 3-chloro-1,4-phenylenediamine, and mixtures thereof.
5. The method of claim 4,
Wherein the acyl halide compound is at least one selected from the group consisting of trimesoyl chloride, isotaryl chlorite, and terephthaloyl chloride.
Treating the porous support on which the polyamide active layer is formed with an aqueous solution containing the superhydrophilic substance of Formula 1 below.
[Chemical Formula 1]

Wherein x is an integer of 70 to 95 and y is an integer of 5 to 30.
8. The method of claim 7,
Wherein the aqueous solution comprises 0.0001 wt% to 10 wt% of the superhydrophilic substance represented by the formula (1).
8. The method of claim 7,
Wherein the treatment is performed by a dipping method.
8. The method of claim 7,
Wherein the superhydrophilic substance of Formula 1 is prepared by mixing 2-hydroxyethyl acrylate and acrylamide in an equivalent ratio of 70:30 to 95: 5 and then reacting.
11. The method of claim 10,
Wherein the reaction is carried out at 45 to 80 DEG C for 1 to 6 hours.