KR101114668B1 - Manufacturing method for polyamide-based reverse osmosis membrane and polyamide-based reverse osmosis membrane manufactured thereby - Google Patents

Abstract

The present invention relates to a method for preparing a polyamide reverse osmosis membrane and a polyamide reverse osmosis membrane prepared by the method, using a post-treatment process and a washing step using an aqueous organic salt solution in a conventional process for preparing a polyamide reverse osmosis membrane. Further introduction can provide a polyamide reverse osmosis membrane with high salt rejection and high flow rate characteristics.

Polyamide reverse osmosis membrane, post-treatment process, organic acid solution, salt rejection rate, flow rate

Description

MANUFACTURING METHOD FOR POLYAMIDE-BASED REVERSE OSMOSIS MEMBRANE AND POLYAMIDE-BASED REVERSE OSMOSIS MEMBRANE MANUFACTURED THEREBY}

The present invention relates to a post-treatment process of a polyamide reverse osmosis membrane and a polyamide reverse osmosis membrane prepared by the method, and more particularly, a polyamide reverse osmosis membrane having a high salt rejection rate and increased flux. It relates to a manufacturing method of.

Osmotic phenomenon is a phenomenon in which a solvent moves between two solutions separated by a semi-permeable membrane from a solution having a low solute concentration to a high solution, and the pressure applied to the solution having a high solute concentration by moving the solvent. It is called osmotic pressure. On the contrary, if the external pressure is applied higher than the osmotic pressure, the solvent moves toward the solution of low solute concentration. This phenomenon is called reverse osmosis, and the reverse osmosis principle is used to drive the semipermeable membrane using the pressure gradient as the driving force. Through this, various salts and organic substances can be separated. That is, reverse osmosis membranes can be used to separate the water from the brine by pressurizing it to prevent passage of the salt and other dissolved ions or molecules.

The purpose of the reverse osmosis process is largely divided into the production of purified water and the concentration of solutes dissolved in raw water. The former includes the desalination of seawater and brine, the manufacture of ultrapure water for the semiconductor industry, and the treatment of various industrial wastewater. Concentration of juices, low alcohol beer and wine production.

The possibility of desalination of water using this reverse osmosis process was first presented by Reid in 1953, and in 1964 by Lobe and Sourirajan as a cellulose acetate, A monolithic asymmetric membrane having a commercial potential composed of a porous support was prepared, and research has been actively conducted on polyamides, polyurethanes, aromatic polysulfones, aromatic polyamides, and the like to compensate for the shortcomings of cellulose membranes.

The reverse osmosis membrane is divided into an integral asymmetric membrane and a thin film composite membrane according to the internal structure. The asymmetric membrane has a salt rejection layer and a porous support under the same material and is easy to manufacture and inexpensive, while having a low salt rejection rate or a low permeation rate. There is this. Recently, a composite film made of a material having different epidermal and support layers has been developed. Such a composite film can select an optimal active layer material, thereby improving the overall performance of the film and crosslinking the active layer. Since it can be given, it has the advantage of obtaining higher chemical resistance.

In order to desalize a large amount of such reverse osmosis membranes commercially, the salt removal rate must be high, and the permeation rate characteristic that can pass the excess water through the membrane even at a relatively low pressure must be excellent. Therefore, there is a demand for the development of a more economical method for producing a reverse osmosis membrane having a high salt rejection rate while having a high salt rejection rate.

One problem to be solved by the present invention is to provide a method for producing a polyamide reverse osmosis membrane further comprising a post-treatment process for imparting high salt rejection rate and high flow rate characteristics.

Another object of the present invention is to provide a polyamide reverse osmosis membrane prepared by the above method.

One aspect of the present invention for achieving the above object, in the method for producing a polyamide reverse osmosis membrane by interfacial polymerization, after the polyamide reverse osmosis membrane is prepared further comprising the following steps in a post-treatment process It relates to a method for producing a polyamide reverse osmosis membrane.

(i) immersing the polyamide reverse osmosis membrane prepared in an organic salt solution comprising an organic acid and an amine, and

(ii) washing the polyamide reverse osmosis membrane with distilled water.

The organic salt solution may include 2 to 10% by weight of organic salt, but is not limited thereto.

Immersion step (i) can be carried out for 10 minutes to 1 hour.

Another aspect of the present invention for achieving the above object relates to a polyamide reverse osmosis membrane prepared by the manufacturing method, the polyamide reverse osmosis membrane comprises a porous support and a polyamide active layer formed on at least one side of the porous support Include.

According to the embodiments of the present invention, it is possible to provide a polyamide reverse osmosis membrane having a high salt rejection rate but having a high salt rejection rate, desalination of seawater and brine, ultrapure water production for the semiconductor industry, and treatment of various industrial wastewater. This can be useful for.

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

In the present invention, in the preparation of the polyamide reverse osmosis membrane, in order to give more improved salt rejection rate and high flow rate characteristics, the present invention provides a post-treatment process in the manufacturing method of polyamide reverse osmosis membrane.

One aspect according to an embodiment of the present invention, in the method for producing a polyamide reverse osmosis membrane by interfacial polymerization, after preparing a polyamide reverse osmosis membrane, a poly-process comprising the following steps further It relates to a method for preparing an amide reverse osmosis membrane.

(i) immersing the polyamide reverse osmosis membrane prepared in an organic salt solution comprising an organic acid and an amine, and

(ii) washing the polyamide reverse osmosis membrane with distilled water.

In general, a polyamide reverse osmosis membrane is coated with a microporous support with an aqueous polyfunctional amine solution, and then contacted with an organic solution including a polyfunctional acyl halide or the like to interfacially polymerize the polyamide, and then dried, and the basic aqueous solution and / or Or it can be prepared by washing with distilled water, but the reverse osmosis membrane thus prepared has been pointed out as a problem of low salt rejection rate and low flow rate.

Accordingly, the present inventors have further introduced the post-treatment process to the manufacturing process of a general polyamide reverse osmosis membrane in order to solve the above problems and provide a polyamide reverse osmosis membrane having a high flow rate and high salt rejection. It was.

Specifically, the aftertreatment process according to the embodiments of the present invention is as follows.

The post-treatment process according to the present invention may be carried out by immersing the polyamide reverse osmosis membrane prepared by interfacial polymerization in an organic salt solution containing an organic acid and an amine, followed by post-treatment and washing with distilled water.

Organic acids usable in embodiments of the present invention include, but are not limited to, camphorsulfonic acid (CSA), hydrochloric acid, acetic acid, methanesulfonic acid or trifluoroacetic acid.

In addition, amines usable in embodiments of the present invention include triethylamine, trimethylamine, tripropylamine, dipropylamine, 1-methylpiperidine, N, N-diethylmethylamine, N, N-dimethyl Ethylamine, N, N-dimethylethanolamine, N, N-dimethyl-4-amino-pyridine, and the like, but are not limited thereto.

The organic salt solution may include 2 to 10% by weight of organic salt, but is not limited thereto.

At this time, the immersion step in the organic salt solution may be carried out by immersing the polyamide reverse osmosis membrane in which the polyamide active layer is formed in an aqueous organic salt solution containing an organic acid and an amine for 10 minutes to 1 hour.

The washing step following the dipping step may be performed by washing for about 30 minutes with distilled water according to a general process.

The post-treatment process of the polyamide reverse osmosis membrane according to the embodiments of the present invention is applicable to all methods of preparing a polyamide reverse osmosis membrane by conventional interfacial polymerization.

For example, a method of manufacturing a polyamide reverse osmosis membrane comprising a post-treatment process according to embodiments of the present invention is as follows.

Specifically, an aqueous polyfunctional amine is coated on a microporous support coated with a polymer support such as polysulfone, and the excess solution is removed to form a first thin film. Next, the microporous support on which the first thin film is formed is contacted with an aliphatic hydrocarbon-based organic solution containing a polyfunctional acyl halide or the like. At this time, the polyamide is produced by the reaction of the polyfunctional amine and the polyfunctional acyl halide due to the interfacial polymerization, and is adsorbed onto the microporous support to form the polyamide active layer as the second thin film. Thereafter, the resulting thin film is dried and washed with a basic aqueous solution and distilled water to prepare a polyamide reverse osmosis membrane.

Subsequently, a post-treatment process is performed to improve the salt rejection rate and the flow rate of the polyamide reverse osmosis membrane thus prepared. That is, the polyamide reverse osmosis membrane prepared in the previous step was immersed for 10 minutes to 1 hour in an aqueous solution containing 2 to 10% by weight of organic salts of organic acids and amines, followed by washing for about 30 minutes by distilled water. The improved polyamide reverse osmosis membrane having high flow rate and high salt removal rate can be prepared.

The microporous support that can be used in the embodiments of the present invention can be used in which a polymer support is cast on a nonwoven fabric such as polyester, such a polymer is polysulfone, polyethersulfone, polycarbonate, polyphenylene oxide, polyimide, It may be selected from the group consisting of polyetherimide, polyether ether ketone, polypropylene, polymethylpentene and polyvinylidene fluoride, but is not necessarily limited thereto.

The pore size of the microporous support is preferably 1 to 500 nm, and when the pore size is 500 nm or more, it is difficult for the coating layer to penetrate between the pores to form a uniform structure.

In the method for producing a polyamide reverse osmosis membrane according to the present invention, a method for coating a polyfunctional amine aqueous solution on a microporous support, such as dip coating, spin coating, spray coating, etc., immersed in a polyfunctional amine aqueous solution by a wet coating method, Known methods are possible, and a continuous process or a handy coating may be used, and the coating process may be performed for 30 seconds to 10 minutes. The polyfunctional amine is an aromatic polyfunctional amine substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxyalkyl group, a hydroxy group or a halogen atom, or a benzidine, diaminobenzidine or an alkyl or halogen atom. It may be a polyfunctional amine such as benzidine derivative substituted with naphthalene diamine. More specific examples of the polyfunctional amine include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,3,5-benzenetriamine, 4-chloro-1,3-phenylenediamine, 5- Chloro-1,3-phenylenediamine, 3-chloro-1,4-phenylenediamine, and the like, but are not limited thereto.

In this case, the polyfunctional amine of the aqueous polyfunctional amine solution is preferably included 0.1 to 20% by weight, more preferably 1.0 to 10% by weight, most preferably 1.5 to 4% by weight may be used.

In addition, according to another embodiment of the present invention, the polyfunctional amine aqueous solution may further include sodium lauryl sulfate, sodium dodecylbenzenesulfonate, camphorsulfonic acid as an additive. In addition, the polyfunctional amine aqueous solution may further include sodium acetate, sodium bicarbonate, triethylamine, or the like as an acid acceptor.

After coating the polyfunctional amine aqueous solution on the microporous support, the excess solution existing on the surface is removed by using a press using a roll, an air knife, or a sponge to form a first thin film.

Subsequently, forming the polyamide active layer on at least one side of the microporous support coated with the aqueous polyfunctional amine solution includes the microporous support having the first thin film and the polyfunctional acyl halide, the polyfunctional sulfonyl halide, or the polyfunctional isocyanate. It is carried out by contacting an aliphatic hydrocarbon-based organic solution, which may be carried out by a dipping or spray method, but is not necessarily limited thereto. The interfacial polymerization step may be performed for 5 seconds to 10 minutes, more preferably 20 seconds to 4 minutes.

In this case, the aliphatic hydrocarbon-based organic solution may include 0.01 to 1% by weight of one or more polyfunctional acyl halides selected from the group consisting of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride.

In addition, the aliphatic hydrocarbon solvent used must not participate in interfacial polymerization, must be free of chemical bonds with acyl halides and must not damage the porous support layer.

After drying the microporous support on which the second thin film of the polyamide active layer is formed, the polyamide reverse osmosis membrane before the post-treatment process may be obtained. The drying and washing steps are not particularly limited, but may be applied to those commonly used in the art, but, for example, if it can be dried at room temperature, and the solvent is considered to have evaporated to some extent, 30 to 120 ℃ After drying completely for 30 seconds to 10 minutes in the state of, and cooling the thin film to room temperature again, and then washed for 30 minutes to 1 hour in an aqueous solution of sodium carbonate at 20 to 80 ℃, then stored in pure water, poly Amide reverse osmosis membranes can be prepared.

Another aspect of the invention relates to a polyamide reverse osmosis membrane prepared according to the above production method. The polyamide reverse osmosis membrane according to embodiments of the present invention includes a porous support and a polyamide active layer formed on at least one side of the porous support. Since the polyamide reverse osmosis membrane has a high salt rejection rate and has a high flow rate characteristic, the polyamide reverse osmosis membrane may be usefully used for desalination of seawater and brine, preparation of ultrapure water for semiconductor industry, and treatment of various industrial wastewater.

Hereinafter, the present invention will be described in more detail with reference to the following examples in order to help understand the present invention, but embodiments according to the present invention may be variously modified, and the scope of the present invention is limited to the following examples. It should not be interpreted.

Preparation Example 1

Casting a solution containing 82% by weight of dimethylformamide and 18% by weight of polysulfone on a polyester nonwoven fabric to a thickness of 160 µm, and immediately immersing it in a distilled water coagulation solution at 25 ° C. to solidify the polysulfone. The microporous substrate was sufficiently washed with water to replace residual solvent in the substrate with water and then stored in pure water.

The polysulfone microporous support obtained as described above was treated with 2% by weight of m-phenylenediamine, 1.5% by weight of benzoic acid, 0.2% by weight of sodium lauryl sulfate, 2.2% by weight of camphorsulfonic acid, 4.4% by weight of triethylamine and residual water. It was immersed in an aqueous polyfunctional amine solution containing for 2 minutes, and the water on the surface was removed. A microporous support coated with an aqueous polyfunctional amine solution was impregnated with an organic solution in which 0.1% by weight of trimezoyl chloride was dissolved in an isopar (IsoPar, Exxon Mobile) solvent for 1 minute, dried in air, and then 0.2% of sodium carbonate. After washing for 30 minutes with an aqueous solution containing%, washed again with pure water at room temperature to prepare a polyamide reverse osmosis membrane first.

Example 1

The polyamide reverse osmosis membrane prepared primarily in Preparation Example 1 above was immersed for 1 hour in an organic salt solution containing 4.4% by weight of camphorsulfonic acid and 2.2% by weight of triethylamine, and then washed again with pure water at room temperature. The process was carried out to prepare a polyamide reverse osmosis membrane.

Example 2

A polyamide reverse osmosis membrane was prepared in the same manner as in Example 1, except that 2.2 wt% of camphorsulfonic acid and 1.1 wt% of triethylamine were used as the organic salt solution.

Example 3

A polyamide reverse osmosis membrane was prepared in the same manner as in Example 1, except that 6.6% by weight of camphorsulfonic acid and 3.3% by weight of triethylamine were used as the organic salt solution in Example 1 above.

Example 4

A polyamide reverse osmosis membrane was manufactured in the same manner as in Example 1, except that 6 wt% of camphorsulfonic acid and 4 wt% of N, N-dimethylethylamine were used as the organic salt solution in Example 1 above. .

Example 5

A polyamide reverse osmosis membrane was manufactured in the same manner as in Example 1, except that 1 wt% of 0.1N hydrochloric acid and 4 wt% of triethylamine were used as the organic salt solution in Example 1 above.

Comparative Example 1

A polyamide reverse osmosis membrane was prepared in the same manner as in Example 1, except that 8 wt% of camphorsulfonic acid and 4 wt% of triethylamine were used as the organic salt solution in Example 1 above.

Comparative Example 2

The polyamide reverse osmosis membrane prepared primarily in Preparation Example 1 was evaluated without performing the post-treatment process performed in Examples 1 to 5.

<Method for evaluating the properties of reverse osmosis membrane>

The physical properties of the polyamide reverse osmosis membranes prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were measured by the following method and the results are shown in Table 1 below.

Experimental Example 1 Evaluation of the Drift

The flow rate was passed through 35,000ppm NaCl aqueous solution through a polyamide reverse osmosis membrane for 40 minutes at 25 ℃, 800psi conditions, and then the permeation flow rate was measured.

Experimental Example 2-Salt Exclusion Rate Evaluation

Salt exclusion rate was calculated by the following formula.

Where
R is the salt exclusion rate,
C _f is the concentration of solute in the feed water,
C _p is the solute concentration in the permeate.

As can be seen in Table 1, in the case of post-treatment using an aqueous organic salt solution containing a specific content of organic acids and amines (Examples 1 to 5) while maintaining a high salt rejection rate of 99% or more Polyamide reverse osmosis membranes having flow characteristics can be obtained, but in the case of polyamide reverse osmosis membranes prepared without this post-treatment process (Comparative Example 2), performance is poor in terms of both salt rejection and flow rate. It can be confirmed that, when the solution of the organic salt content of 12% by weight is used (Comparative Example 1), the flow rate is improved, but it can be seen that the salt rejection rate is lower than before the post-treatment process.

That is, from the results of the experimental examples for the above examples and comparative examples, the polyamide reverse osmosis membrane prepared by performing the post-treatment process as the present invention can achieve a high flow rate characteristics while maintaining a high salt rejection rate can confirm.

Although the present invention has been described in detail with reference to preferred embodiments of the present invention, these are merely exemplary, and those skilled in the art to which the present invention pertains have various modifications and equivalents therefrom. It will be appreciated that embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (8)

A method for producing a polyamide reverse osmosis membrane by interfacial polymerization, the method of manufacturing a polyamide reverse osmosis membrane further comprising the following steps as a post-treatment process after preparing the polyamide reverse osmosis membrane: (i) immersing the polyamide reverse osmosis membrane prepared in an organic salt solution comprising an organic acid and an amine, and (ii) washing the polyamide reverse osmosis membrane with distilled water. The method of claim 1, wherein the organic acid is selected from the group consisting of camphorsulfonic acid, hydrochloric acid, acetic acid, methanesulfonic acid and trifluoroacetic acid. The compound of claim 1 wherein the amine is triethylamine, trimethylamine, tripropylamine, dipropylamine, 1-methylpiperidine, N, N-diethylmethylamine, N, N-dimethylethylamine, N, N -Dimethylethanolamine and N, N-dimethyl-4-amino-pyridine. The method for producing a polyamide reverse osmosis membrane. The method of claim 1, wherein the organic salt solution comprises 2 to 10% by weight of an organic salt. The method of claim 1, wherein the organic salt solution comprises an organic acid and an amine in a ratio of 2: 1. The method for preparing a polyamide reverse osmosis membrane according to claim 1, wherein (i) the dipping step is performed for 10 minutes to 1 hour. Prepared according to the method of any one of claims 1 to 6, A polyamide reverse osmosis membrane comprising a porous support and a polyamide active layer formed on at least one side of the porous support. The method of claim 7, wherein the porous support is a microporous support, wherein the nonwoven fabric is polysulfone, polyethersulfone, polycarbonate, polyphenylene oxide, polyimide, polyetherimide, polyether ether ketone, polypropylene, polymethylpentene and A polyamide reverse osmosis membrane, wherein at least one polymer material selected from the group consisting of polyvinylidene fluoride is cast.