KR20160039918A - Manufacturing method for reverse osmosis membrane and reverse osmosis membrane manufactured thereby - Google Patents

Abstract

The present invention relates to a manufacturing method of a reverse osmosis membrane, and a reverse osmosis membrane manufactured thereby. The manufacturing method of a reverse osmosis membrane comprises the steps of: forming a polyamide layer on one side of a porous support; and touching a solvent comprising a hydroxy group on one side of the porous support under pressure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane, a reverse osmosis membrane, and a reverse osmosis membrane,

The present invention relates to a method for producing a reverse osmosis membrane and a reverse osmosis membrane produced thereby.

The phenomenon that the solvent moves between the two solutions isolated 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 principle of reverse osmosis, it is possible to separate various salts and organic substances through a semipermeable membrane using a pressure gradient as a driving force. Reverse osmosis membranes using this reverse osmosis membrane are used for separating molecular-level materials and removing salts from brine or sea water to supply domestic, architectural and industrial water.

The most important function of the reverse osmosis membrane is to maintain a high permeation rate of the solvent even at a relatively low pressure and a high salt rejection rate at the boundary of the membrane. For this purpose, a reverse osmosis membrane having a high salt removal rate and a high permeation flow rate has been proposed by forming a thin active layer on the porous support to maintain the mechanical strength of the membrane. (U.S. Patent No. 4,277,344)

A typical example of the reverse osmosis membrane disclosed in U.S. Patent No. 4,277,344 is a polyamide-based reverse osmosis membrane. The polyamide-based reverse osmosis membrane is manufactured by forming a polyamide active layer on a microporous support . More specifically, a polysulfone layer is formed on a nonwoven fabric to form a microporous support, and the microporous support is immersed in an aqueous solution of m-phenylenediamine (MPD) to form meta- phenylenediamine (MPD) layer, which is then immersed or coated in an organic solvent of 1,3,5-benzenetricarbonyl trichloride (TMC) to form meta-phenylenediamine , MPD) layer is contacted with 1,3,5-benzenetricarbonyl trichloride to form a polyamide layer by interfacial polymerization. By contacting the nonpolar organic solution with the polar organic solution, the polymerization takes place at the interface only and forms a very thin polyamide active layer. The unreacted aromatic amine on the active layer causes an oxidation reaction with chlorine, thereby stabilizing the active layer from further oxidation reaction.

However, the above-described reverse osmosis membrane has a problem of shortening the replacement time of membranes due to the rapid decrease of chlorine resistance over time. Therefore, a method for increasing the specific surface area of the active layer has been proposed in order to slow down the degree of chlorine resistance of the reverse osmosis membrane. Japanese Patent Laid-Open Publication No. 10-337454 discloses that after the active layer is formed, the surface of the skin layer of the reverse osmosis separator is soaked in an acidic solution so as to make the surface of the skin layer rugged or wrinkled, and Korean Patent Publication No. 1998-0068304 A method of increasing the surface roughness by post-treating with a strong acid after manufacturing a reverse osmosis composite membrane has been disclosed.

However, as disclosed in Japanese Patent Application Laid-Open No. 10-337454, when the separation membrane having the active layer formed therein is immersed in the acid solution, the surface of the separation membrane is negatively charged, and positively charged contaminants adhere to the separation membrane, thereby lowering the permeability of the separation membrane Therefore, there is a disadvantage that a separate post-treatment step of coating the surface of the separation membrane with an electrically neutral polymer is required.

In addition, the method disclosed in Korean Patent Laid-Open Publication No. 1998-0068304, in order to overcome the problem of negative charge on the surface of the reverse osmosis membrane, the polyamide composite membrane is treated with an acid to increase the surface roughness, And there is a disadvantage in that a separate post-treatment step is required in the same manner.

U.S. Patent 4,277,344 Japanese Patent Application Laid-Open No. 10-337454 Korean Patent Publication No. 1998-0068304

The present invention provides a method for producing a reverse osmosis membrane and a reverse osmosis membrane produced thereby.

According to one embodiment of the present disclosure, there is provided a method of forming a porous support, comprising: forming a polyamide layer on one side of a porous support; And

And contacting the porous support and the polyamide layer with a solvent containing a hydroxyl group under pressure.

According to another embodiment of the present disclosure, there is provided a reverse osmosis membrane produced by the above production method, wherein the content of unreacted organic matter is less than 700 mg / m ² .

According to another embodiment of the present disclosure, a porous support; And a polyamide layer provided on one side of the porous support, wherein the content of the unreacted organic material is less than 700 mg / m ² .

According to some embodiments of the present invention, the reverse osmosis membrane having a small residual organic content and excellent salt rejection rate and water permeability can be provided by the above-described method of producing a reverse osmosis membrane.

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

In this specification, when a part is referred to as "including " an element, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

In this specification, when a member is located on another member, it includes not only the case where the member is in contact with the other member but also the case where another member exists between the two members.

According to one embodiment of the present disclosure, there is provided a method of forming a porous support, comprising: forming a polyamide layer on one side of a porous support; And

And contacting the porous support and the polyamide layer with a solvent containing a hydroxyl group under pressure.

According to the above-described embodiment, the polyamide layer is formed on one surface of the porous support in the production of the reverse osmosis membrane, and then the hydroxyl-containing solvent is contacted with the porous support and the polyamide layer, have. Particularly, by sufficiently carrying out the contact under the pressure condition, the hydroxy group-containing solution is sufficiently diffused into the interior of the porous support, whereby not only the polyamide layer but also the unreacted organic matter remaining in the interior of the porous support can be sufficiently dissolved.

According to an embodiment of the present invention, the step of forming the polyamide layer on one surface of the porous support may use interfacial polymerization. For example, the step of forming the polyamide layer may include forming an amine aqueous solution layer on the porous support; And dropping the organic solution onto the amine aqueous solution layer. The organic solution dropped on the amine aqueous solution layer is not particularly limited as long as it is capable of interfacial polymerization with the amine aqueous solution to form polyamide, and includes, for example, an acyl halide compound.

According to one example, after an amine aqueous solution layer is formed on the porous support, a droplet of the organic solution containing the acyl halide compound is dispersed in the amine aqueous solution layer at a predetermined time interval while the porous support having the amine aqueous solution layer is moved, Followed by interfacial polymerization to form a polyamide layer.

For example, the porous support includes a nonwoven fabric and a polymer layer provided on at least one side of the nonwoven fabric.

The material of the porous support may be a polymer, and examples of the polymer include polysulfone, polyethersulfone, polycarbonate, polyphenylene oxide, polyimide, poly But are not limited to, polyetheretherketone, polyetheretherketone, polypropylene, polymethylpentene, polymethyl chloride, polyvinylidene fluoride, and the like. It is not. As the material of the porous support, a polymer may be used. Specifically, the polymer may be polysulfone.

The thickness of the polymer layer provided on at least one side of the nonwoven fabric and the nonwoven fabric may be adjusted as necessary. The thickness of the nonwoven fabric may be 60 to 100 탆. The thickness of the polymer layer May be 20 [mu] m to 50 [mu] m.

The pore size of the porous support is preferably 1 nm to 500 nm. When the pore size is more than 500 nm, the coating layer is difficult to form a uniform structure due to permeation through the pores. When the pore size is less than 1 nm, the amine aqueous solution is hardly permeated.

Such a porous support may be formed by casting the above-mentioned polymer on a nonwoven fabric such as polyester to improve the mechanical strength of the membrane.

The thickness of the porous support can be adjusted as needed, for example, from 80 탆 to 150 탆.

The amine aqueous solution layer may include an amine compound, camphorsulfonic acid (CSA), and a solvent. The amine compound may include at least one member selected from the group consisting of meta-phenylenediamine (MPD) and triethylamine (TEA).

The amine aqueous solution layer may include at least one amine compound selected from meta-phenylenediamine (MPD) and triethylamine (TEA), camphorsulfonic acid (CSA) and a solvent

The amine compound is preferably a meta-phenylenediamine (MPD: m-phenylendiamine).

The solvent may comprise at least one selected from water and isopropyl alcohol (IPA).

According to one example, the composition of the amine aqueous solution layer is 0.5 to 8% by weight of an amine compound, 40 to 90% by weight of water, 2 to 5% by weight of camphorsulfonic acid (CSA) %, And isopropyl alcohol (IPA) is 0 to 40% by weight, but not limited thereto.

As the method of forming the amine aqueous solution layer on the porous support, bar coating, slot die coating, dipping, coating or coating methods are usually used, but the present invention is not limited thereto.

The organic solution means a solution containing a material capable of interfacial polymerization with the amine aqueous solution to form polyamide. For example, the organic solution may comprise an acyl halide compound and a solvent.

As the acyl halide solution, 1,3,5-benzenetricarbonyl trichloride (TMC) may be used.

The organic solution may comprise 1,3,5-benzenetricarbonyl trichloride (TMC: 1,3,5-benzenetricarbonyl trichloride) and a solvent.

The solvent may be hexane.

The organic solution has a composition of 0.03 wt% to 0.2 wt% of 1,3,5-benzenetricarbonyl trichloride (TMC), 99.99 wt% to 99.97 wt% of hexane %. ≪ / RTI >

When dropping the organic solution, a droplet, a syringe, a spray nozzle, or the like may be used, but the present invention is not limited thereto.

According to another embodiment of the present invention, the solvent containing the hydroxy group may be used alone or in a mixture of two or more, and may be contained in an aqueous solution as required.

According to another embodiment of the present invention, the solvent containing the hydroxy group is contained in an amount of 20 to 100% by weight based on the aqueous solution.

According to another embodiment of the present invention, the solvent containing the hydroxy group includes one or more selected from the group consisting of methanol, ethanol, isopropyl alcohol, ethylene glycol, and glycerin, no.

According to another embodiment of the present invention, the contacting of the solvent containing the hydroxy group is performed by coating, coating, spraying or spraying, but is not limited thereto.

The contacting of the solvent containing the hydroxy group is carried out under the condition of pressurization. According to one example, the contact under the condition of pressurization can be carried out by a pressurized application method.

The solvent containing the hydroxy group is pressure-coated to sufficiently dissolve the unreacted organic material remaining in the porous support and the polyamide layer, and sufficiently diffuse into the porous support.

The pressure-sensitive coating may be applied to a substrate such as an inkjet coating, a capillary coating, a bar coating, a slot die coating, a plasma polymerization coating, a sputtering coating, Evaporation coating, chemical vapor deposition coating or iCVD coating (initiated chemical vapor deposition coating) may be used alone or in combination. However, the present invention is not limited thereto.

According to another embodiment of the present invention, a solvent containing a hydroxy group is coated on one side of the polyamide layer at a pressure of 30 mL / min to 70 mL / min.

It is preferable to pressurize the solvent containing the hydroxy group at a rate of 40 mL / min to 60 mL / min. It is more preferable to pressurize the solvent containing the hydroxy group at a rate of 50 mL / min.

When the solvent containing the hydroxy group is pressurized to a pressure of less than 30 mL / min, the solvent is not sufficiently applied to the polyamide layer and the porous support, and the residue can not be removed. When the pressure exceeds 70 mL / min, There is a drawback that it is applied and flows down.

According to one embodiment of the present invention, the content of unreacted organic material in the reverse osmosis membrane produced by the above production method is less than 700 mg / m ² .

The content of the unreacted organic material can be analyzed using a device known in the art. For example, a UV spectrometer, a gas chromatography / mass spectrometry (GC / MS), or the like may be used, but the present invention is not limited thereto.

After making the standard solution from 100 ppm to 600 ppm of the unreacted organic matter, the absorbance is measured with a UV spectrophotometer. The area of the extinction curve for each concentration was integrated to obtain a first calibration curve showing absorbance versus concentration, and then the prepared reverse osmosis membrane was cut into 5 cm × 24 cm to elute the unreacted organic matter in the solution to be contained in the reverse osmosis membrane Calculate the amount of unreacted organics.

The unreacted organic material means an organic material that is not polymerized with polyamide but remained unreacted in the material added during the production of the polyamide layer. The unreacted organic material may be represented by an organic material other than polyamide.

According to another embodiment of the present disclosure, the unreacted organics include monomers of amines.

The amine monomer may include at least one member selected from the group consisting of m-phenylendiamine (MPD), triethylamine (TEA), and camphorsulfonic acid (CSA) But is not limited thereto.

The amine monomer may be m-phenylendiamine (MPD).

According to one embodiment of the present disclosure, the flow rate at which a solution comprising a salt at a concentration of 32,000 ppm at a reverse osmosis pressure of 800 psi passes through a reverse osmosis membrane according to the embodiments of the present invention described above is from 25GFD to 35GFD.

According to another embodiment of the present disclosure, the salt rejection rate of the reverse osmosis membrane is 99.3% to 99.6% based on the concentration of the salt-containing solution.

According to one embodiment of the present disclosure, a porous support; And a polyamide layer provided on one side of the porous support, wherein the content of the unreacted organic material is less than 700 mg / m ² .

Wherein the unreacted organic material comprises the porous support; And a polyamide layer provided on one side of the porous support.

The porous support, the polyamide layer and the unreacted organic material may be those described in the above-described embodiments of the present invention.

According to another embodiment of the present invention, the reverse osmosis membrane has a flow rate when a solution containing a salt having a reverse osmosis pressure of 800 psi and a concentration of 32,000 ppm passes through is from 25GFD to 35GFD.

According to another embodiment of the present disclosure, the salt rejection rate when the solution containing the salt passes through the reverse osmosis membrane is 99.3% to 99.6% based on the concentration of the solution containing the salt.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

Manufacturing method of reverse osmosis membrane

<Production Example>

Polysulfone prepared on a nonwoven fabric of 100 mu m made of polyester was cast. To cast the polysulfone, an 18 wt% polysulfone solid is put into a solution of N, N-dimethylformamide (DMF), and the resultant is dissolved at 80 to 85 ° C for 12 hours or more. When a uniform liquid phase is obtained, 45 占 퐉 polysulfone was cast thereon. A reverse osmosis membrane was prepared using the prepared porous polysulfone support. The polysulfone support was an aqueous solution layer containing 2 wt% of MPD (m-phenylendiamine) and 1 wt% of triethylamine (TEA) and 2.3 wt% of camphorsulfonic acid (CSA) The excess aqueous solution on the support after coating was removed using a 25 psi roller. Next, an organic solution containing 0.2 wt% 1,3,5-benzenetricarbonyl trichloride in a hexane solvent (Sigma Aldrich) was added to the coated support surface And then the organic solution was continuously added dropwise thereto in succession to obtain a reverse osmosis membrane.

The initial salt rejection rate and the initial permeate flow rate were measured at 25 ° C at a flow rate of 4.5 L / min of 32,000 ppm sodium chloride solution. The reverse osmosis membrane cell apparatus used for the membrane evaluation was a flat membrane type permeation cell, a high pressure pump, . The structure of the planar type transmissive cell was a cross-flow type with an effective permeation area of 28 cm ² . After the washed membrane was installed in the permeation cell, preliminary operation was performed for about 1 hour by using the third distilled water for stabilization of the evaluation equipment. After that, 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. The amount of water permeated for 10 minutes was measured to calculate the flow rate, and a conductivity meter And the salt excretion rate was calculated by analyzing the salt concentration before and after the permeation.

A UV spectrometer was used to analyze the amount of residue in the prepared reverse osmosis membrane. The standard solution was prepared from 100 ppm to 600 ppm of meta-phenylenediamine (MPD), which is the most abundant residual organic material in the reverse osmosis membrane, and the absorbance was measured. The area of the absorption curve for each concentration was integrated to obtain a first calibration curve showing the absorbance versus concentration. Then, the prepared reverse osmosis membrane was cut into 5 cm × 24 cm, and the residue was eluted in the solution to calculate the amount of residual meta-phenylenediamine (MPD: m-phenylendiamine) contained in the reverse osmosis membrane.

Performance evaluation of reverse osmosis membrane

&Lt; Example 1 >

The reverse osmosis membrane was prepared through the same process as the polyamide membrane. At this time, 100 wt% ethanol was applied at 50 mL / min to the reverse osmosis membrane, which was dried, and was applied to the entire reverse osmosis membrane. The prepared membrane was washed with distilled water and its performance was measured under a pressure of 800 psi in a NaCl aqueous solution of 32,000 ppm each, or under a pressure of 250 psi in an aqueous NaCl solution of 2,000 ppm. The measurement results are shown in Table 1. The amount of residual meta-phenylenediamine (MPD: m-phenylendiamine) in the reverse osmosis membrane was measured and the results are shown in Table 2.

&Lt; Example 2 >

The reverse osmosis membrane was prepared and evaluated in the same manner as in Example 1, except that 80 wt% ethanol was added to the dried reverse osmosis membrane at a flow rate of 50 mL / min to coat the entire reverse osmosis membrane. The performance measurement results are shown in Table 1.

&Lt; Example 3 >

The reverse osmosis membrane was prepared and evaluated in the same manner as in Example 1, except that 50 wt% ethanol was added to the dried reverse osmosis membrane at a flow rate of 50 mL / min to coat the entire reverse osmosis membrane. The performance measurement results are shown in Table 1.

<Example 4>

The reverse osmosis membrane was prepared and evaluated in the same manner as in Example 1, except that 20 wt% ethanol was added to the dried reverse osmosis membrane at a flow rate of 50 mL / min to coat the entire reverse osmosis membrane. The performance measurement results are shown in Table 1.

&Lt; Comparative Example 1 &

Reverse osmosis membrane was prepared in the same manner as in Example 1, except that ethanol was applied to the reverse osmosis membrane to apply it to the entire reverse osmosis membrane. The performance measurement results are shown in Table 1. The amount of residual meta-phenylenediamine (MPD: m-phenylendiamine) in the reverse osmosis membrane was measured and the results are shown in Table 2.

As shown in Table 1, the reverse osmosis membrane of the present invention has relatively high salt rejection and water permeability characteristics as compared with the reverse osmosis membrane produced by Comparative Example 1. Particularly, when 100 wt% ethanol was used as in Example 1, water permeability increased by 16% or more as compared with Comparative Example 1.

As shown in Table 2, the amount of residual meta-phenylenediamine (MPD: m-phenylendiamine) in the reverse osmosis membrane of Example 1 of the present invention was reduced by 10% or more .

Claims (11)

Forming a polyamide layer on one side of the porous support; And
And contacting the polyamide layer with a solvent containing a hydroxyl group under pressure. The method of claim 1, wherein forming the polyamide layer comprises: forming an amine aqueous solution layer on the porous support; And
And dropping the organic solution onto the amine aqueous solution layer. The method according to claim 2, wherein the amine aqueous solution layer comprises at least one amine compound selected from meta-phenylenediamine (MPD) and triethylamine (TEA), camphorsulfonic acid (CSA) Wherein the reverse osmosis membrane is formed by a method comprising the steps of: The method of claim 2, wherein the organic solution comprises 1,3,5-benzenetricarbonyl trichloride (TMC: 1,3,5-benzenetricarbonyl trichloride) and a solvent. The process for producing a reverse osmosis membrane according to claim 1, wherein a solvent containing one or more of the above hydroxy groups is mixed with water and used as an aqueous solution. [6] The method of claim 5, wherein the solvent containing the hydroxyl group is contained in an amount of 20% by weight to 100% by weight with respect to the aqueous solution. The method of claim 1, wherein the solvent containing the hydroxyl group comprises one or more selected from the group consisting of methanol, ethanol, isopropyl alcohol, ethylene glycol, and glycerin. The method according to claim 1, wherein the contacting of the solvent containing the hydroxy group is carried out by coating, coating, spraying or spraying. The method according to claim 1, wherein the solvent containing the hydroxy group is contacted by pressure coating at a rate of 30 mL / min to 70 mL / min. A reverse osmosis membrane produced by the method of any one of claims 1 to 9, wherein the content of unreacted organic matter is less than 700 mg / m ² . A porous support; And a polyamide layer on one side of the porous support, wherein the content of unreacted organic material is less than 700 mg / m ² .