KR20200021727A - Reverse osmosis membrane for osmotic backwashing process and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a reverse osmosis membrane suitable for an osmosis backwashing process and a manufacturing method thereof. More specifically, the present invention relates to a reverse osmosis membrane suitable for an osmosis backwashing process and a manufacturing method thereof. The reverse osmosis membrane prevents exfoliation of a polymer support layer when performing high pressure osmosis backwashing owing to excellent bonding between a porous support and the polymer support layer, has excellent membrane durability and lifespan, and is capable of minimizing the reduction in the salt rejection rate and the permeable flow rate of the reverse osmosis membrane after the osmosis backwashing.

Description

Reverse osmosis membrane for osmotic backwashing process and method of manufacturing the same

The present invention relates to a reverse osmosis membrane suitable for an osmotic backwashing process and a method of manufacturing the same, and more particularly, to excellent membrane durability by preventing the separation of the polymer support layer during high-pressure osmotic backwashing by excellent bonding between the porous support and the polymer support layer. The present invention relates to a reverse osmosis membrane suitable for an osmotic reverse washing process capable of minimizing a decrease in permeation flow rate and salt excretion rate of the reverse osmosis membrane after osmotic reverse washing, and a method of manufacturing the same.

With the rapid growth of the membrane filtration market worldwide, the development of membrane filtration technology has led to the emergence of numerous membrane manufacturers and membrane construction companies. The membrane filtration process is a low pressure membrane filtration process operated at low pressure, such as MF (microfiltration), UF (ultrafiltration, ultrafiltration), NF (nanofiltration, nanofiltration), RO (reverse osmosis, reverse). It can be classified into a high pressure membrane filtration process operated at high pressure, such as osmosis, and in recent years, interest in high pressure membrane filtration processes is rapidly increasing.

On the other hand, the membrane used in the membrane filtration process, such as organic fouling (organic fouling), inorganic fouling (inorganic fouling), particle fouling (particular fouling), bio-fouling (bio-fouling), etc. Occur and its performance continues to decrease. Therefore, in order to restore the permeation performance of the membrane reduced with the operating time of the membrane filtration process to the initial state, the cleaning in place (CIP) through physical cleaning and chemicals such as high-pressure osmotic backwashing is performed. Membrane contamination is classified into reversible membrane irreversible and irreversible membrane fouling. Reversible membrane fouling involves physical washing such as high-pressure osmotic backwashing and chemical washing for irreversible membrane fouling.

The conventional reverse osmosis membrane may cause a phenomenon in which the polymer support layer and the hydrophilic selective layer are peeled off during osmotic backwashing, and thus, the salt excretion rate and permeate flow rate of the reverse osmosis membrane after osmotic backwashing are lowered, thereby degrading the life of the membrane.

Republic of Korea Patent No. 10-0973831

The present invention has been made in view of the above, it is excellent in bonding between the porous support and the polymer support layer prevents the phenomenon that the polymer support layer is peeled off even under high pressure osmotic backwashing has excellent membrane durability and lifespan after osmotic backwashing It is an object of the present invention to provide a reverse osmosis membrane suitable for an osmotic reverse cleaning process and a method for manufacturing the same, which can minimize the decrease in the permeation rate and the salt rejection rate of the reverse osmosis membrane.

Another object of the present invention is to provide a reverse osmosis module having excellent salt rejection rate, permeate flow rate and durability even after osmotic backwashing, including the reverse osmosis membrane according to the present invention.

In order to solve the above problems, the present invention provides a sulfonated polysulfone polymer compound, a first polymer solution including a first polymer compound, and a second polymer solution including a second polymer compound on a porous support. It provides a method for producing a reverse osmosis membrane comprising the step of forming a polymer support layer on which the second polymer support layer is formed on the first polymer support layer and (2) forming a hydrophilic selective layer on the polymer support layer.

According to an embodiment of the present invention, the solvent is at least one selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc) It may include.

In addition, according to an embodiment of the present invention, step (1) may be performed at 20 ~ 90 ℃.

In addition, according to an embodiment of the present invention, the first polymer solution and the second polymer solution may be treated at a weight ratio of 1: 1 to 1: 3.

In addition, according to a preferred embodiment of the present invention, the first polymer solution and the second polymer solution may be treated at a weight ratio of 1: 1.5 to 1: 2.5.

In addition, according to an embodiment of the present invention, step (1) may be performed by using a dual layer-slot coating method.

In addition, according to one embodiment of the present invention, the sulfonated polysulfone polymer may be included in 0.1 to 10% by weight based on the weight of the first polymer support layer.

The present invention also provides a porous support, a first polymer support layer formed on the porous support and including a sulfonated polysulfone polymer compound and a first polymer compound, and formed on the first polymer support layer and including a second polymer compound. It provides a reverse osmosis membrane comprising a polymer support layer comprising a second polymer support layer and a hydrophilic selective layer formed on the polymer support layer.

According to one embodiment of the present invention, the sulfonated polysulfone polymer compound may be at least one selected from sulfonated polysulfone, sulfonated polyethersulfone and sulfonated polyallylethersulfone.

In addition, according to one embodiment of the present invention, the sulfonated polysulfone polymer compound may be represented by the following formula (1).

In Formula 1, m / (n + m) is 0.2 to 0.7, and x is 50 to 2300.

In addition, according to an embodiment of the present invention, the weight average molecular weight of the sulfonated polysulfone polymer compound may be 65,000 ~ 150,000.

In addition, according to an embodiment of the present invention, the first polymer support layer and the second polymer support layer may be included in a weight ratio of 1: 1 to 1: 3.

According to a preferred embodiment of the present invention, the first polymer support layer and the second polymer support layer may be included in a weight ratio of 1: 1.5 to 1: 2.5.

In addition, according to an embodiment of the present invention, the thickness of the first polymer support layer may be 10 to 75 μm, and the thickness of the second polymer support layer may be 10 to 75 μm.

In addition, according to an embodiment of the present invention, the first polymer compound and the second polymer compound may be a polysulfone polymer compound, a polyamide polymer compound, a polyimide polymer compound, a polyester polymer compound, an olefin polymer It may include at least one selected from a compound, polyvinylidene fluoride and polyacrylonitrile.

In addition, according to an embodiment of the present invention, the hydrophilic selective layer is a polyamide-based polymer compound, polypiperazine-based polymer compound, polyphenylene diamine-based polymer compound, polychlorophenylene diamine-based polymer compound and polybenzidine-based polymer compound It may include at least one selected from among.

In addition, according to one embodiment of the present invention, the reverse osmosis membrane is backwashed at a pressure of 3bar, and can satisfy the following conditions (a) and (b) for 2,000 ppm sodium chloride aqueous solution at a temperature of 25 ℃ and a pressure of 225 psi have.

(a) 5% or less salt removal rate change rate

(b) Permeation rate change rate of 15% or less

The present invention also provides a reverse osmosis module comprising a reverse osmosis membrane according to the present invention.

According to the present invention is excellent in the bonding between the layers in the membrane to prevent the separation of the polymer support layer during high-pressure osmotic backwashing has excellent membrane durability and lifespan and can minimize the decrease in permeation flow rate and salt rejection rate of the reverse osmosis membrane after osmotic backwashing The reverse osmosis membrane can be implemented, and the reverse osmosis module including the reverse osmosis membrane according to the present invention can maximize the cumulative treatment quantity and minimize the maintenance cost.

1 is a schematic cross-sectional view of a reverse osmosis membrane according to an embodiment of the present invention.
2 is a cross-sectional SEM photograph of the reverse osmosis membrane according to Example 3.
3 is an exploded perspective view of the reverse osmosis module according to an embodiment of the present invention.

In the conventional reverse osmosis membrane, a polymer support layer is formed by directly applying a polymer solution onto a porous support, and since the surface smoothness of the porous support is low, the polymer support layer formed on the porous support has a problem of being peeled off during osmotic backwashing. Accordingly, the hydrophilic selective layer formed on the polymer support layer is also peeled off, which causes a problem that the performance of the reverse osmosis membrane is significantly lowered.

In the method for preparing a reverse osmosis membrane according to the present invention, in order to solve the above-mentioned problems, a first polymer solution including a sulfonated polysulfone polymer compound is firstly treated on a porous support first, and then the first polymer solution is The second polymer solution is treated on the treated porous support to form a polymer support layer having a structure in which the first polymer support layer and the second polymer support layer are stacked. By including a hydrophilic sulfonated polysulfone polymer compound in the first polymer support layer, the first polymer support layer is formed on the porous support with high smoothness, so that the bonding force with the porous support can be excellent, and as the second polymer support layer. Due to this, the reverse osmosis membrane may have excellent durability and at the same time minimize the decrease in permeation flow rate.

However, when the polymer support layer is composed of only the first polymer support layer containing the sulfonated polysulfone polymer compound, the permeation flow rate of the reverse osmosis membrane can be significantly reduced. When the polymer support layer is composed only of the second polymer support layer, the polymer support layer may be peeled off during osmotic backwashing. Since the reverse osmosis membrane of the present invention is composed of a first polymer support layer and a second polymer support layer containing a sulfonated polysulfone polymer compound, the reverse osmosis membrane of the present invention has excellent binding force with the porous support and at the same time the permeate flow rate and salt rejection rate of the reverse osmosis membrane There is an advantage that can be expressed at an excellent level.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

The manufacturing method of the reverse osmosis membrane which concerns on this invention is demonstrated.

First, in step (1), a sulfonated polysulfone polymer compound, a first polymer solution including a first polymer compound and a solvent, and a second polymer solution including a second polymer compound and a solvent are formed on the porous support 110. To form a second polymer support layer 122 on the first polymer support layer 121 and the first polymer support layer 121.

The porous support is not particularly limited as long as it serves as a support of the reverse osmosis membrane, but may preferably be a fabric. Specifically, the fabric refers to a woven fabric, a knitted fabric or a nonwoven fabric, and the fabric has a lateral direction as weaved with warp and weft yarns, and the specific direction of the knitted fabric may vary depending on the knitting method. It may have a directionality of. In addition, the nonwoven fabric has no longitudinal or transverse direction unlike the woven or knitted fabric.

When the fabric is a fabric, it is possible to control the physical properties such as porosity, porosity, strength, and permeability of the desired porous support by adjusting the type of fiber, the fineness, the density of the weft yarn, and the fabric of the fiber forming the weft yarn.

In addition, when the fabric is knitted, the physical properties such as porosity, porosity, strength, and permeability of a desired porous support may be controlled by adjusting the kind, fineness, texture, gauge, and cut of the fibers included in the knitted fabric. .

In addition, when the fabric is a nonwoven fabric, physical properties such as porosity, porosity, strength, and permeability of a desired porous support may be controlled by adjusting the type, fineness, fiber length, basis weight, density, etc. of the fibers included in the nonwoven fabric. .

The material of the porous support may typically serve as a porous support of the reverse osmosis membrane, and can be used without limitation as long as it is used for the porous support of the conventional reverse osmosis membrane. As a non-limiting example, synthetic fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene, or natural fibers including cellulose-based can be used.

The porous support may adjust the physical properties of the membrane according to porosity and hydrophilicity. In addition, the porous support may have an air permeability of 2 cc / cm ² · sec or more, preferably have a air permeation of 2 ~ 20 cc / cm ² · sec and the pore size of the average pore of the porous support is 1 To 600 μm, and preferably 5 to 300 μm. When the air permeability and the pore size of the average pore are satisfied, water can be smoothly introduced and water permeability can be increased.

In addition, the porous support satisfies the high hydrophilicity, thereby reducing the resistance to water, and can secure a high bonding strength with the first polymer support layer containing the sulfonated polysulfone polymer compound, which is a hydrophilic polymer, and the first polymer. The support layer may be formed on the porous support with high smoothness, thereby effectively preventing the polymer support layer from peeling off during osmotic backwashing. To this end, the contact angle of the porous support may be 0.1 to 74 °, preferably 0.1 to 60 °.

In addition, the porous support may have a thickness of 20 to 150 μm, and if the thickness is less than 20 μm, the strength of the entire membrane may decrease, and if the thickness exceeds 150 μm, the flow rate may be reduced.

Next, the first polymer support layer and the second polymer support layer included in the reverse osmosis membrane of the present invention will be described.

The first polymer support layer may include a hydrophilic sulfonated polysulfone polymer compound so that the first polymer support layer may be formed on the porous support with high smoothness, and may have excellent bonding strength with the porous support.

On the other hand, when the polymer support layer is composed of only the first polymer support layer containing a sulfonated polysulfone polymer compound, the permeation flow rate of the reverse osmosis membrane may be reduced, and if the polymer support layer is composed of only the second polymer support layer, the polymer support layer may be In order to prevent this, the polymer support layer of the present invention may be composed of a first polymer support layer and a second polymer support layer to improve durability of the reverse osmosis membrane, and to minimize a decrease in permeation flux and salt rejection rate.

As described above, the first polymer solution and the second polymer solution are 1: 1 to 1: 3, more preferably 1 to realize excellent durability of the polymer support layer without lowering the permeation rate and the salt rejection rate of the reverse osmosis membrane. It can be treated at a weight ratio of 1: 1.5 to 1: 2.5.

If the weight ratio is less than 1: 1, the permeate flow rate and salt rejection rate of the reverse osmosis membrane prepared by consolidation may decrease.If the weight ratio exceeds 1: 3, the polymer support layer of the reverse osmosis membrane may be peeled off after reverse washing. It may be difficult to achieve the object of the present invention.

In addition, when the first polymer solution and the second polymer solution satisfy the weight ratio condition of 1: 1.5 to 1: 2.5, the reverse osmosis membrane may have excellent durability, and thus the permeate flow rate and salt rejection ratio may be more excellent after reverse washing.

When the polymer support layer is formed by adjusting the weight ratio of the first polymer solution and the second polymer solution as described above, the first polymer support layer and the second polymer support layer are 1: 1 to 1: 3, more preferably 1: It may be included in the polymer support layer in a weight ratio of 1.5 ~ 1: 2.5.

If the weight ratio is less than 1: 1, the permeate flow rate and salt rejection rate of the reverse osmosis membrane prepared by consolidation may decrease.If the weight ratio exceeds 1: 3, the polymer support layer of the reverse osmosis membrane may be peeled off after reverse washing. It may be difficult to achieve the object of the present invention.

In addition, when the first polymer support layer and the second polymer support layer satisfy the weight ratio condition of 1: 1.5 to 1: 2.5, the durability of the reverse osmosis membrane may be excellent, so that the permeate flow rate and the salt rejection ratio may be more excellent after the reverse washing.

In addition, the first polymer support layer and the second polymer support layer may include the same polymer compound, thereby minimizing or preventing the occurrence of defects in the polymer support layer.

The treatment method of the first polymer solution and the second polymer solution may be used without limitation as long as it is a conventional method of treating a polymer solution used in forming a polymer support layer in the art, and sequentially treating the first polymer solution and the second polymer solution. Alternatively, the treatment may be performed at the same time, but preferably, a dual layer-slot coating method may be used, which may prevent degradation of properties and shorten processing time. After treating the polymer solution to remove the solvent contained in the polymer solution to form a polymer support layer, the solvent removal method may use a phase inversion method of replacing the solvent and the non-solvent, specifically The non-solvent may be at least one selected from water, ethanol and methanol, but may vary depending on the components of the solvent.

The solvent contained in the first polymer solution and the second polymer solution was removed to form a first polymer support layer and a second polymer support layer on the porous support, and the polymer support layer of the reverse osmosis membrane was not deteriorated without lowering the permeation flow rate and the salt excretion rate. The thicknesses of the first polymer support layer and the second polymer support layer formed to realize excellent durability may be preferably 10 to 75 μm and 10 to 75 μm, respectively.

If the thickness of the first polymer support layer is less than 10 μm, the binding force between the first polymer support layer and the porous support may not be expressed at a desired level, so that the polymer support layer may be peeled from the porous support after backwashing, and may exceed 75 μm. In this case, the permeate flow rate of the reverse osmosis membrane may be lowered.

In addition, if the thickness of the second polymer support layer is less than 10㎛, the pressure resistance of the reverse osmosis membrane may be lowered, so that the polymer support layer may be peeled from the porous support after reverse washing, and if the thickness exceeds 75㎛, the permeate flow rate of the reverse osmosis membrane may be lowered. have.

The sulfonated polysulfone polymer compound may be included in the first polymer solution to improve the binding force with the porous support.

The sulfonated polysulfone polymer compound may be included in an amount of 0.1 to 10% by weight, more preferably 5 to 9% by weight, based on the weight of the first polymer solution to impart hydrophilicity to the first polymer support layer. have.

If the sulfonated polysulfone polymer compound is included in less than 0.1% by weight based on the weight of the first polymer solution, the water permeability and hydrophilicity of the first polymer support layer may not be expressed to the desired level, 10 weight When it exceeds%, the strength of the first polymer support layer may be lowered or the film formation may be substantially difficult.

In addition, when the sulfonated polysulfone polymer compound is included in 5 to 9% by weight based on the weight of the first polymer solution, the water permeability and hydrophilicity of the first polymer support layer may be more excellent.

The sulfonated polysulfone polymer compound may be at least one selected from sulfonated polysulfone, sulfonated polyether sulfone, and sulfonated polyallyl ether sulfone, and preferably represented by the following Chemical Formula 1.

[Formula 1]

Since the polysulfone polymer represented by Chemical Formula 1 has a very stable characteristic by electrostatic attraction due to resonance electrons between aromatic groups around -SO ₂ group, stability, chemical resistance, and various pore sizes in a wide temperature range It can have and its mechanical strength is excellent.

In Formula 1, m / (n + m) is defined as a sulfonation degree of the sulfonated polysulfone polymer compound represented by Formula 1, and a preferable value of m / (n + m) is 0.2 to 0.7. . When m / (n + m) is less than 0.2, the hydrophilic property of the first polymer support layer is weak, and thus the bonding force with the porous support may be lowered. When m / (n + m) exceeds 0.7, the first polymer support layer The strength of can be lowered. When the sulfonation degree (m / (n + m)) is 0.2 to 0.7, the hydrophilicity is imparted to the first polymer support layer, thereby improving the bonding strength with the porous support and decreasing the salt excretion rate and permeation flux of the reverse osmosis membrane after the reverse washing process. Can be minimized.

In addition, in the sulfonated polysulfone polymer compound represented by Chemical Formula 1, x may be 50 to 2300, and a weight average molecular weight may be 65,000 to 150,000.

The first polymer compound is at least one selected from polysulfone polymer compound, polyamide polymer compound, polyimide polymer compound, polyester polymer compound, olefin polymer compound, polyvinylidene fluoride and polyacrylonitrile Preferably, it may include a polysulfone polymer compound.

The solvent included in the first polymer solution may be used without limitation as long as it is a solvent capable of dissolving the sulfonated polysulfone polymer compound and the first polymer compound, preferably N-methyl-2-pyrrolidone (NMP). , Dimethylformamide (DMF), dimethylsulfoxide (DMSO) and dimethylacetamide (DMAc).

The solvent included in the first polymer solution may be included in an amount of 65 to 93 wt% based on the weight of the first polymer solution. If the solvent is included in less than 65% by weight, the viscosity of the first polymer solution is excessively increased may be difficult to form a film, when included in excess of 93% by weight, the strength of the prepared reverse osmosis membrane is reduced or the first polymer solution The viscosity of the very low may be difficult to form a film.

The sulfonated polysulfone polymer compound, the first polymer compound and a solvent may be mixed to prepare a first polymer solution, the temperature of the solvent when the first polymer solution may be 20 ~ 90 ℃, if the solvent When the temperature of less than 20 ℃, the sulfonated polysulfone-based polymer compound or the first polymer compound may not dissolve, when the temperature exceeds 90 ℃ the viscosity of the first polymer solution is lowered, the first polymer support layer of the desired thickness It can be difficult to form.

The second polymer compound is at least one selected from polysulfone polymer compound, polyamide polymer compound, polyimide polymer compound, polyester polymer compound, olefin polymer compound, polyvinylidene fluoride and polyacrylonitrile Preferably, it may include a polysulfone polymer compound.

The solvent contained in the second polymer solution may be used without limitation as long as it is a solvent capable of dissolving the second polymer compound. Preferably, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), At least one selected from dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc).

The solvent included in the second polymer solution may be included in an amount of 65 to 93% by weight based on the weight of the second polymer solution. If the solvent is included in less than 65% by weight, the viscosity of the second polymer solution is excessively increased may be difficult to form a film, when contained in excess of 93% by weight, the strength of the prepared reverse osmosis membrane is reduced or the second polymer solution The viscosity of the very low may be difficult to form a film.

The second polymer compound and the solvent may be mixed to prepare a second polymer solution. When preparing the second polymer solution, the temperature of the solvent may be 20 to 90 ° C., and if the temperature of the solvent is less than 20 ° C., The second polymer compound may not be dissolved, and when it exceeds 90 ° C., the viscosity of the first polymer solution may be lowered, thereby making it difficult to form a second polymer support layer having a desired thickness.

The first polymer solution and the second polymer solution are treated on a porous support and then the solvent contained in the first polymer solution and the second polymer solution is removed so that the first polymer support layer and the second polymer support layer are formed on the porous support. It can be solidified in a laminated structure.

Next, as step (2), the hydrophilic selective layer 130 is formed on the second polymer support layer 122.

The hydrophilic selective layer can be used without limitation as long as it can be used as a hydrophilic selective layer of the reverse osmosis membrane in the art, preferably a polyamide-based polymer compound, polypiperazine-based polymer compound, polyphenylene diamine-based polymer compound It may include at least one selected from a polychloro phenylene diamine-based high molecular compound and a polybenzidine-based high molecular compound, more preferably may include a polyamide-based high molecular compound.

The method of forming the hydrophilic selective layer may be different depending on the type of material included in the hydrophilic selective layer to be selected, but the method may be based on a conventional method of forming a hydrophilic selective layer according to the type of material. As an example, a method of forming a hydrophilic selective layer made of a polyamide-based high molecular compound among materials that can be included in the hydrophilic selective layer will be described.

In order to form a hydrophilic selective layer made of a polyamide-based high molecular compound on the second polymer support layer, the membrane prepared by the above step (1) is immersed in an aqueous solution containing a polyfunctional amine, and then comprises a polyfunctional acid halogenated compound. The hydrophilic selective layer may be formed by contacting the organic solution.

Specifically, the multifunctional amine may be a polyamine including a primary amine or a secondary amine as a material having 2-3 amine functional groups per monomer. In this case, as the polyamine, an aromatic primary diamine is used as metaphenylenediamine, paraphenylenediamine, orthophenyldiamine, and a substituent, and another example is cycloaliphatic primary diamine such as aliphatic primary diamine and cyclohexene diamine. Cycloaliphatic secondary amines such as piperazine, aromatic secondary amines and the like can be used. More preferably, metaphenylenediamine is used in the polyfunctional amine, and the concentration is preferably in the form of an aqueous solution containing 0.5 to 10% by weight of metaphenylenediamine, more preferably metaphenylenediamine is 1 To 4% by weight, even more preferably 1.5 to 2.5% by weight may be included, through which there is an advantage that can express a more improved flux.

When forming the hydrophilic selective layer, the aqueous solution containing the polyfunctional amine may be immersed for 0.1 to 10 minutes, more preferably 0.5 to 1 minute on the polymer support layer.

In addition, the material that reacts with the polyfunctional amine used in forming the hydrophilic selective layer is a polyfunctional acid halogen compound, preferably a polyfunctional acyl halide, more preferably trimezoyl chloride, isophthaloyl chloride, 5-methoxy At least one selected from -1,3-isophthaloyl chloride and terephthaloyl chloride can be used. The polyfunctional acyl halide may be dissolved in an aliphatic hydrocarbon solvent at 0.01 to 2% by weight, wherein the aliphatic hydrocarbon solvent may be a mixture of structural isomers of n-alkanes having 5 to 12 carbon atoms and saturated or unsaturated hydrocarbons having 8 carbon atoms. Cyclic hydrocarbons having 5 to 7 carbon atoms can be used. Preferably, the polyfunctional acyl halide-containing solution may be dissolved in an aliphatic hydrocarbon solvent at 0.01 to 2% by weight, more preferably 0.05 to 0.3% by weight. In this case, the polyfunctional acid halogen compound may be immersed in the membrane treated with the polyfunctional Ami-containing aqueous solution for 0.1 to 10 minutes, more preferably 0.5 to 1 minute.

The thickness of the hydrophilic selective layer may be 0.1 ~ 1㎛, if the thickness is less than 0.1㎛ salt removal ability may be lowered, if it exceeds 1㎛ may be the permeate flow rate of the reverse osmosis membrane.

Next, the reverse osmosis membrane according to the present invention will be described.

The reverse osmosis membrane according to the present invention includes a porous support, a first polymer support layer, a second polymer support layer, and a hydrophilic selective layer. Since the configuration of the porous support, the first polymer support layer, the second polymer support layer, and the hydrophilic selective layer is the same as the configuration described above in the method of manufacturing the reverse osmosis membrane, a detailed description thereof will be omitted.

Since the reverse osmosis membrane according to the present invention has excellent binding force between the porous support, the first polymer support layer and the second polymer support layer, it prevents the phenomenon that the polymer support layer is peeled from the porous support during backwashing, thereby improving the life of the reverse osmosis membrane and excellent flow rate even after reverse washing. And salt excretion rates.

Specifically, after the reverse osmosis membrane is backwashed at a pressure of 3bar, the following conditions (a) and (b) may be satisfied for 2,000 ppm aqueous sodium chloride solution at a temperature of 25 ° C. and a pressure of 225 psi, and thereby the reverse osmosis membrane of the present invention. It can be confirmed that it has this excellent durability.

(a) 5% or less salt removal rate change rate

(b) Permeation rate change rate of 15% or less

Meanwhile, the present invention provides a reverse osmosis module including the reverse osmosis membrane according to the present invention.

The reverse osmosis module may employ a configuration of a reverse osmosis module commonly used in the art. As a non-limiting example, the reverse osmosis membrane may be spiral wound in a porous permeate outlet pipe together with a spacer for forming a flow path. It may be wound to and may include an end cap for the shape stability of the membrane wound at both ends of the wound membrane.

Figure 3 is an exploded perspective view of the reverse osmosis membrane module according to an embodiment of the present invention.

The size and shape of the pressure case may be unlimited within the range in which the reverse osmosis membrane module can be accommodated. Preferably, since the plurality of filter assemblies are wound in a spiral wound shape, the shape may be a cylinder. However, the shape of the pressure case is not limited thereto. The material of the pressure case may be used without limitation in the case of a pressure case material commonly used in the reverse osmosis membrane module in the art.

Referring to FIG. 3, the reverse osmosis membrane module 1000 includes a plurality of filter assemblies wound around the outlet tube 1400 in a spiral winding type. The cross-sectional diameter of the reverse osmosis membrane module is the diameter of the outlet tube and the osmosis membrane assembly. May vary depending on the number, thickness, and the like.

The outlet pipe 1400 has a plurality of holes, and fluid flowing through the outlet pipe 1400 flows into the reverse osmosis membrane 1100 of the filter assembly through the hole. Specifically, the solution A of two solutions A and B having different concentrations flows inside the pressure case and outside the reverse osmosis membrane 1100 of the filter assembly, and the solution B is reverse osmosis membrane 1100 of the filter assembly through holes in the outlet pipe 1400. It will flow inside. Through this, two solutions (A, B) having different concentrations are positioned inside and outside the reverse osmosis membrane 1100 of the filter assembly, thereby generating and acting an osmotic pressure. However, the two solutions A and B may be injected in the same direction as in FIG. 3, but this is one example. Alternatively, the two solutions A and B may be injected in different directions according to the purpose.

The reverse osmosis membrane module may include an outer spacer 1300 between the plurality of filter assemblies and an inner spacer 1200 between the reverse osmosis membranes. The outer spacers 1300 and the inner spacers 1200 are influent flow paths, and may form flow paths through which fluids flowing between different filter assemblies, for example, A solution, can flow smoothly.

The material, shape, and size of the spacer and the end cap may adopt a configuration of the spacer and the end cap which are commonly used in the reverse osmosis module in the art, so a detailed description thereof will be omitted. The reverse osmosis membrane wound as described above may be housed in the outer case, and the material, size, and shape of the outer case may also be the material, size, and shape of the outer case commonly used in the reverse osmosis module in the art. In addition, the reverse osmosis membrane wound as described above may be wrapped using fiber reinforced plastics (FRP) instead of the outer case.

Example 1

Sulfonated polysulfone polymer compound represented by Formula 1 (m / (n + m) = 0.5, x = 1,000) 1.3% by weight, polysulphone 16.2% by weight and dimethylformamide 82.5% by weight of the first polymer solution Was prepared at a temperature of 60 ° C.

A second polymer solution consisting of 17.5 wt% polysulfone and 82.5 wt% dimethylformamide was prepared at a temperature of 60 ° C.

After discharging the first polymer solution and the second polymer solution at a weight ratio of 1: 1.43 on the porous support, which is a polyester nonwoven fabric, using a double layer slot coating method, the polymer support layer was formed on the porous support by phase transition in distilled water at 25 ° C. Formed.

The membrane was immersed in an aqueous solution containing 2.0% by weight of metaphenylenediamine for 1 minute, and then water on the surface was removed by a compression method. The substrate was immersed in an organic solution containing 0.1% by weight of trimezoyl chloride for 1 minute, followed by interfacial polymerization, followed by natural drying at room temperature for 1 minute and 30 seconds to form a hydrophilic selective layer made of polyamide.

Thereafter, a reverse osmosis membrane was prepared by immersing in 0.2 wt% sodium carbonate solution for 2 hours to remove unreacted residues.

(Examples 2 to 6)

In the same manner as in Example 1, during the preparation of the polymer support layer, the first polymer solution and the second polymer solution were discharged at a weight ratio shown in Table 1 below to prepare a reverse osmosis membrane.

(Comparative Example 1)

The same as in Example 1,

A reverse osmosis membrane was prepared by forming a polymer support layer using a polymer solution composed of 17.5 wt% polysulfone and 82.5 wt% dimethylformamide.

Experimental Example 1

After evaluating the initial performance of the reverse osmosis membranes prepared in Examples and Comparative Examples, in order to evaluate the peeling stability of the reverse osmosis membrane, the performance after reverse washing of the reverse osmosis membrane was evaluated.

Initial performance evaluation of the reverse osmosis membrane was performed by adding 2,000 ppm of sodium chloride solution (25 ° C., 225 psi) onto the hydrophilic selective layer of the reverse osmosis membrane, and measuring the flow rate of the water produced on the opposite side of the reverse osmosis membrane, and then converting it into unit area and flow rate per unit pressure. .

The salt excretion rate was calculated through the following formula 1 by measuring the ion conductivity (TDS: Total Dissolved Solids) of the produced water.

[Calculation 1]

% Salt removal rate = {1- (conductivity value of produced water / conductivity value of raw water)} Х 100

In addition, the performance evaluation after reverse washing of the reverse osmosis membrane was operated for 30 minutes at a pressure of 3 bar (43.5 psi), and then the flow rate and salt removal rate were measured again.

division Polymer support layer Reverse osmosis membrane Content of Sulfonated Polysulfone Polymer Compound in First Polymer Solution Weight ratio of the first polymer solution and the second polymer solution Initial performance Performance after backwash Salt excretion decrease
(%) Permeate flow rate increase rate
(%) Psf
(weight%) Salt rejection
(%) Permeate flow rate
(GFD) Salt rejection
(%) Permeate flow rate
(GFD) Comparative Example 1 - - 98.0 17.3 77.5 39.0 20.5 125.4 Example 1 1.3 1: 1.43 95.9 27.5 84.9 34.9 11.0 26.9 Example 2 1.3 1: 1.55 96.1 26.4 90.1 31.1 6.0 17.8 Example 3 1.3 1: 2.14 97.8 22.7 92.8 26.1 5.0 15.0 Example 4 1.3 1: 2.38 96 23.1 90.7 26.0 5.3 12.6 Example 5 1.3 1: 2.86 83.8 23.2 83.5 25.7 0.3 10.8 Example 6 1.3 1: 3.22 82.1 23.8 70.1 42.6 12.0 79.0

Referring to Table 1 above, Comparative Example 1, which does not include the first polymer support layer, and Example 6, in which the weight ratio of the first polymer solution and the second polymer solution is greater than 1: 3, shows a significant salt rejection ratio after backwashing. It is believed that the polymer support layer is peeled off during backwashing due to a decrease in permeate flow rate.

Examples 1 to 5 prepared with a weight ratio of the first polymer solution and the second polymer solution in a range of 1: 1 to 1: 3 show a relatively low salt excretion after backwashing, and thus have excellent peeling stability of the polymer support layer. In particular, in Examples 2 to 4, the decrease in salt excretion after backwashing was much lower, and thus, the peeling stability of the polymer support layer was remarkably excellent.

Experimental Example 2

A cross-sectional SEM image of the reverse osmosis membrane prepared in Example was performed.

Figure 2 is a cross-sectional SEM image of the reverse osmosis membrane prepared in Example 3, referring to Figure 2, it can be seen that the polymer support layer is formed over the upper surface and the inside of the porous support, which is a hydrophilic liquor in the first polymer support layer It is determined that the first polymer support layer is formed with high smoothness on the porous support by including the phonated polysulfone polymer compound, so that the bonding force with the porous support is excellent, and the second polymer support layer is flat on the first polymer support layer. It is formed to be able to implement the reverse osmosis membrane is improved to be excellent in the peeling stability of the polymer support layer durability.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments set forth herein, and those skilled in the art who understand the spirit of the present invention may add components within the scope of the same idea. Other embodiments may be easily proposed by changing, deleting, adding, etc., but this is also within the scope of the present invention.

100: reverse osmosis membrane
110: porous support
121: first polymer support layer
122: second polymer support layer
130: hydrophilic selective layer
1000: reverse osmosis membrane module
1100: reverse osmosis membrane
1200: internal spacer
1300: external spacer
1400: outlet pipe

Claims (18)

(1) treating a sulfonated polysulfone polymer compound, a first polymer solution containing a first polymer compound, and a second polymer solution containing a second polymer compound on a porous support to form a second polymer on a first polymer support layer. Forming a polymer support layer having a polymer support layer formed thereon; And
(2) forming a hydrophilic selective layer on the polymer support layer;
Method for producing a reverse osmosis membrane comprising a.
The method of claim 1,
The solvent is a method for producing a reverse osmosis membrane comprising at least one selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc).
The method of claim 1,
Step (1) is a method for producing a reverse osmosis membrane is carried out at 20 ~ 90 ℃.
The method of claim 1,
The first polymer solution and the second polymer solution is a method for producing a reverse osmosis membrane is treated in a weight ratio of 1: 1 to 1: 3.
The method of claim 4, wherein
The first polymer solution and the second polymer solution is a method of producing a reverse osmosis membrane is treated in a weight ratio of 1: 1.5 ~ 1: 2.5.
The method of claim 1,
Step (1) is a reverse osmosis membrane manufacturing method performed by using a dual layer-slot coating (dual layer-slot coating).
The method of claim 1,
The sulfonated polysulfone polymer compound is a method for producing a reverse osmosis membrane is contained in 0.1 to 10% by weight based on the weight of the first polymer solution.

Porous support;
A first polymer support layer formed on the porous support and including a sulfonated polysulfone polymer compound and a first polymer compound, and a second polymer support layer formed on the first polymer support layer and including a second polymer compound A polymeric support layer; And
A hydrophilic selective layer formed on the polymer support layer;
Reverse osmosis membrane comprising a.
The method of claim 8,
The sulfonated polysulfone polymer compound is at least one selected from sulfonated polysulfone, sulfonated polyether sulfone, and sulfonated polyallyl ether sulfone.
The method of claim 8,
The sulfonated polysulfone polymer compound is a reverse osmosis membrane represented by Formula 1:
[Formula 1]

In Formula 1, m / (n + m) is 0.2 to 0.7, and x is 50 to 2300.
The method of claim 8,
Reverse osmosis membrane of the weight average molecular weight of the sulfonated polysulfone polymer compound is 65,000 ~ 150,000.
The method of claim 8,
The first polymer support layer and the second polymer support layer are reverse osmosis membranes included in a weight ratio of 1: 1 to 1: 3.
The method of claim 12,
The first polymer support layer and the second polymer support layer are reverse osmosis membranes included in a weight ratio of 1: 1.5 to 1: 2.5.
The method of claim 8,
The first polymer support layer has a thickness of 10 to 75 μm, and the second polymer support layer has a thickness of 10 to 75 μm.
The method of claim 8,
The first polymer compound and the second polymer compound are polysulfone polymer compounds, polyamide polymer compounds, polyimide polymer compounds, polyester polymer compounds, olefin polymer compounds, polyvinylidene fluoride and polyacrylonitrile. Reverse osmosis membrane comprising at least one selected from among.
The method of claim 8,
The hydrophilic selective layer is a reverse osmosis membrane comprising at least one selected from a polyamide polymer compound, a poly piperazine polymer compound, a polyphenylene diamine polymer compound, a polychloro phenylene diamine polymer compound and a polybenzidine polymer compound.
The method of claim 8,
After the reverse osmosis membrane was backwashed at a pressure of 3 bar, the reverse osmosis membrane satisfies the following conditions (a) and (b) for 2,000 ppm aqueous sodium chloride solution at a temperature of 25 ° C. and a pressure of 225 psi:
(a) 5% or less salt removal rate change rate
(b) Permeation rate change rate of 15% or less
Reverse osmosis module comprising a reverse osmosis membrane according to any one of claims 8 to 17.

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