KR20180107612A - Reverse-osmosis membrane having excellent salt rejection and method for manufacturing thereof - Google Patents

Abstract

Provided is a manufacturing method of a reverse osmosis membrane with a high salt rejection rate. According to an embodiment of the present invention, the manufacturing method of a reverse osmosis membrane with a high salt rejection rate comprises the following steps of: (1) forming a porous polymer support layer by treating a polymer solution on at least one surface of a support; and (2) forming a polyamide layer including a formylated amine compound by adding a first solution including a multifunctional amine compound and a compound represented by Chemical Formula 1 to the polymer support layer and then allowing the same to be in contact with a second solution including a multifunctional acid halogen compound. In Chemical Formula 1, R_1, R_2 and R_3 are an alkyl group satisfying a weight average molecular weight of 100 to 5000 and carbon atoms of 1 to 18 or isomers thereof. According to the present invention, a reverse osmosis membrane having a dense pore size can be realized, thereby significantly improving salt rejection efficiency and organic material removal efficiency. At the same time, since there is almost no loss in a permeation flow rate, utilization in various fields in which a reverse osmosis membrane is used can be greatly improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane having excellent salt rejection and method for manufacturing thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane having a high salt rejection rate, a method for producing the reverse osmosis membrane, and a membrane module including the reverse osmosis membrane. More particularly, the present invention relates to a reverse osmosis membrane having a high water rejection rate, Reverse osmosis membrane and a method for producing the same.

In general, the reverse osmosis membrane is used to separate the dissociated material from the solution. Conventional reverse osmosis membranes are used for desalination of brine or seawater, and this desalination process provides fresh or pure water at a level suitable for domestic, agricultural and industrial use. The desalting process using a reverse osmosis membrane filters the ions or molecules dissolved from the solution through the pressurization of the brine, and only the water passes through the reverse osmosis membrane by pressurization. There are several conditions for the desalting process using this reverse osmosis membrane to be commercially used, one of which is a high salt rejection rate. The salt rejection rate for commercial use of conventional reverse osmosis membranes is required to be 97% or more.

A general type of reverse osmosis membrane is a composite membrane composed of a porous support formed by applying a hydrophobic polymeric substance on a polyester nonwoven fabric and a polyamide layer formed on the porous support, wherein the polyamide layer is formed of a polyfunctional amine aqueous solution and a polyfunctional acid It is generally formed by interfacial polymerization of a halogen organic solution. The porous support has a high flow rate as well as a support for the reverse osmosis membrane, and the separation function for the salt is determined in the polyamide layer.

At this time, in order for the reverse osmosis membrane to be used for a large-scale commercial use, the salt rejection rate of the polyamide layer must be high and a large amount of water must be permeable even at a relatively low pressure. As a result, studies on reverse osmosis membranes have been focused on, with high salt removal rates, and further studies for improving the flow rate and chemical resistance have been continued.

However, reverse osmosis membranes having an excellent salt removal rate and excellent water permeation flow rate are not disclosed, and it is required to develop a reverse osmosis membrane production technique having high salt rejection rate and high water permeability.

Patent application No. 2012-0141506

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a reverse osmosis membrane module that maintains a high water permeability and an excellent salt rejection rate, and a reverse osmosis membrane module including the reverse osmosis membrane module.

Another object of the present invention is to provide a process for preparing a reverse osmosis membrane having a high water permeability and an excellent salt rejection rate.

(1) a step of treating a polymer solution on at least one surface of a support to form a porous polymer support layer (2) a step of forming a polymeric support layer by mixing a polyfunctional amine compound and a compound represented by the following formula And then contacting the first solution with a second solution comprising a polyfunctional acid halide compound to form a polyamide layer comprising a formylated amine compound; The present invention also provides a method for preparing a high salt rejection reverse osmosis membrane.

[Chemical Formula 1]

R ₁ , R ₂ and R ₃ are an alkyl group or an isomer thereof having a weight average molecular weight of 100 to 5000 and a carbon number of 1 to 18.

According to an embodiment of the present invention, the first solution of step (2) may include any one of compounds represented by the following formulas (2) and (3).

(2)

(3)

In addition, the first solution may include 0.04 to 50 parts by weight of the multifunctional amine compound represented by Formula 1, based on 100 parts by weight of the multifunctional amine compound.

In the step (2), the polymer support layer is immersed in a first solution containing a polyfunctional amine compound and a compound represented by the following formula (1) for 5 to 600 seconds, and a second solution containing a polyfunctional acid halide compound To form a polyamide layer comprising an amine compound that has been contacted and formylated.

The polymer solution of the step (1) may be at least one selected from the group consisting of a polysulfone polymer, a polyamide polymer, a polyimide polymer, a polyester polymer, an olefin polymer, polyvinylidene fluoride, a polybenzimidazole polymer, Rhenium and rhenitrile, and the like.

The polymer solution of step (1) may be selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), or dimethylacetamide And may include any one or more of the solvents.

In addition, the polyfunctional amine compound in the step (2) may include at least one selected from the group consisting of metaphenylenediamine, paraphenylenediamine, orthophenyldiamine, and dimethylenepiperazine.

In addition, the polyfunctional acid halide compound of the step (2) may be at least one compound selected from the group consisting of trimesoyl chloride, isophthaloyl chloride, tepaloyl chloride, 1,3,5-cyclohexanetricarbonyl chloride and 1,2,3,4- Cyclohexanetetracarboxylic acid, and cyclohexanetetracarbonyl chloride.

The present invention also relates to a support comprising a porous polymeric support layer formed on at least one side of the support and a polyamide layer formed on the polymeric support layer, wherein the polyamide layer comprises a polyfunctional amine compound and a formylated a reverse osmosis membrane having a high salt rejection ratio including an amine group formylated.

[Chemical Formula 1]

R ₁ , R ₂ and R ₃ are an alkyl group or an isomer thereof having a weight average molecular weight of 100 to 5000 and a carbon number of 1 to 18.

The present invention also provides a reverse osmosis module including the reverse osmosis membrane.

According to the present invention, a reverse osmosis membrane having a dense pore size can be realized, and the salt removal efficiency and organic material removal efficiency can be greatly improved. At the same time, there is little loss in permeate flow, which can greatly enhance the utilization of reverse osmosis membranes in various fields.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Conventional reverse osmosis membrane research has focused on improvement of resistance to contamination, chemical resistance and water permeation, and it is a reverse osmosis membrane capable of simultaneously improving the salt rejection rate and water permeability, The research on this is insufficient.

(1) a step of treating a polymer solution on at least one surface of a support to form a porous polymer support layer; (2) a first solution containing a polyfunctional amine compound and a compound represented by the following formula And then forming a polyamide layer containing an amine compound formylated by contacting with a second solution containing a polyfunctional acid halide compound, thereby preparing a high salt rejection reverse osmosis membrane having the above- I tried to solve the problem.

[Chemical Formula 1]

R ₁ , R ₂ and R ₃ are an alkyl group or an isomer thereof having a weight average molecular weight of 100 to 5000 and a carbon number of 1 to 18.

In step (1) of the present invention, a step of treating a polymer solution on at least one surface of a support to form a porous polymer support layer is performed.

The support is not particularly limited as long as it is a support for a reverse osmosis membrane, but may be a fabric. Specifically, the fabric means a fabric, a knitted fabric, or a nonwoven fabric. The fabric has a vertical and horizontal orientation as it is woven with warp and weft. The knitted fabric may have a specific directionality depending on the knitting method, Direction. ≪ / RTI > Further, the nonwoven fabric has no longitudinal and transverse directions unlike the above-mentioned fabric or knitted fabric.

 When the fabric is a fabric, physical properties such as porosity, pore size, strength, permeability, etc. of the target support can be controlled by controlling the type of fiber forming the fiber, the fineness, the density of the fiber, and the texture of the fabric.

In addition, when the fabric is a knitted fabric, properties such as porosity, pore size, strength, and permeability of the desired support can be controlled by controlling the type of fibers, fineness, texture of the knitted fabric, gauges, cuts and the like contained in the knitted fabric.

In addition, when the fabric is a nonwoven fabric, properties such as porosity, pore size, strength, permeability, etc. of the desired support can be controlled by controlling the type, fineness, fiber length, basis weight, density and the like of the fibers included in the nonwoven fabric.

The material of the support may serve as a support for the membrane, and may be used without limitation as long as it is used for a support of a conventional separation membrane. By way of non-limiting example, synthetic fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene; Or natural fibers including cellulosic fibers; Can be used.

The support preferably has an average pore size of 1 to 100 mu m, more preferably 1 to 50 mu m. When the average pore size is less than 1 탆, there is a problem of lowering the flow rate, and there may be a problem such as generating differential pressure of the filter. When the average pore size exceeds 100 탆, the mechanical strength of the support is lowered, There is a problem that can not be done.

The support of the present invention preferably has a thickness of 20 to 150 mu m, and if it is less than 20 mu m, the strength and supporting ability of the entire film are insufficient, and if it exceeds 150 mu m, the flow rate may be decreased.

Next, the polymer solution to be treated on at least one side of the support will be described.

The solvent contained in the polymer solution is not particularly limited as long as it can dissolve the polymer material contained in the polymer solution uniformly without forming precipitates, but more preferably N-methyl-2-pyrrolidone (NMP) , Dimethylformamide (DMF), dimethylsulfoxide (DMSO), or dimethylacetamide (DMAc), or the like.

The polymeric material may be a polymeric substance contained in a conventional reverse osmosis membrane polymeric support layer. In consideration of mechanical strength, it is preferable to use a polymeric material having a weight average molecular weight in the range of 65,000 to 150,000, A polyimide-based polymer, a polyester-based polymer, an olefin-based polymer, polyvinylidene fluoride, a polybenzimidazole polymer, and polyacrylonitrile.

The polymer solution may preferably contain 7 to 35% by weight of the polymer material. If the content of the polymeric substance is less than 7% by weight, the strength is lowered and the solution viscosity is low. Thus, the film is difficult to manufacture and has a problem. When it exceeds 35% by weight, the concentration of the polymer solution is too high.

The polymer support layer used in the reverse osmosis membrane of the present invention is a general microporous support layer and is not particularly limited in its kind but is generally large enough to permit permeation of permeated water and large enough to interfere with the ultra- Should not. At this time, the pore size of the porous support layer is preferably from 1 to 500 nm, and when the thickness exceeds 500 nm, the ultra thin film may sink into the pore size after the formation of the thin film, so that it may be difficult to achieve the required flat sheet structure.

Next, in step (2) of the present invention, (2) a first solution containing a polyfunctional amine compound and a compound represented by the following formula (1) is added to the polymer support layer and then a second solution containing a polyfunctional acid halide compound To form a polyamide layer comprising an amine compound formylated by contact with a solution.

[Chemical Formula 1]

In step (2), a part of the polyfunctional amine compound contained in the first solution reacts with the compound represented by the formula (1) to form an amine compound formylated. The formylated functional group is then no longer reacted with the acid halide compound contained in the second solution, so that the crosslinking reaction does not proceed, and a part of the polyfunctional amine compound that has not reacted with the compound represented by formula (1) React with the acid halide compound contained in the solution to form a polyamide layer.

In this case, the amine compound modified by formylation influences the surface free volume and pore size of the polyamide layer to control the flow rate and salt rejection rate. In other words, the formylated functional group does not react with the acid halide compound contained in the second solution, thereby interfering with the crosslinking reaction, thereby increasing the number of pores of the polyamide layer itself, thereby increasing the flow rate. In addition, since the formyl group is located in the generated pores, the effect of reducing the free volume of the pores is improved and the salt rejection ratio is improved.

The polyfunctional amine compound contained in the first solution may be a polyamine having a primary amine or a secondary amine as a material having 2 to 3 amine functional groups per monomer. As the polyamines, aromatic primary diamine is used as the metaphenylenediamine, paraphenylenediamine, orthophenyldiamine and the substituent. As another example, aliphatic primary diamine and cycloaliphatic primary diamine such as cyclohexenediamine , Cycloaliphatic secondary amines such as piperazine, and aromatic secondary amines. More preferably, the polyfunctional amine compound is selected from the group consisting of metaphenylenediamine, and the concentration thereof is preferably in the form of an aqueous solution containing 0.5 to 10 wt% of metaphenylenediamine, more preferably 1 to 3 % By weight may be contained.

At this time, the desired salt rejection rate and water permeability can be controlled by adjusting the concentrations of the polyfunctional amine compound and the compound represented by the formula (1). For example, the compound represented by Formula 1 may be contained in an amount of 0.04 to 50 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the polyfunctional amine compound. If the compound represented by Formula 1 is contained in an amount of less than 0.04 part by weight based on 100 parts by weight of the polyfunctional amine compound, the polyfunctional amine compound may not sufficiently react with the compound represented by Formula 1, If the amount of the compound represented by the formula (1) is more than 50 parts by weight based on 100 parts by weight of the polyfunctional amine compound, the polyfunctional amine compound and the compound represented by the formula (1) Or the desired water permeability can not be obtained.

According to an embodiment of the present invention, in order to improve the rejection rate of the organic compound, the compound that reacts with the polyfunctional amine compound may be any one of the compounds represented by the following formulas (2) and (3) Lt; / RTI >

(2)

(3)

Next, by reacting a part of the polyfunctional amine compound which has not reacted with the compound represented by the formula (1) with a second solution containing an acid halide compound, a polyamide by crosslinking at the contact interface of the first solution and the second solution To form a layer.

The material that reacts with the polyfunctional amine compound used in forming the polyamide layer of the present invention is a polyfunctional acid halide compound, that is, a polyfunctional acyl halide. Preferably at least one group selected from the group consisting of trimethoyl chloride, isophthaloyl chloride, tephtaloyl chloride, 1,3,5-cyclohexanetricarbonyl chloride and 1,2,3,4-cyclohexanetetracarbonyl chloride. It may be used alone or in combination to include any one or more of them.

The polyfunctional acyl halide may be dissolved in an aliphatic hydrocarbon solvent in an amount of 0.01 to 2% by weight, wherein the aliphatic hydrocarbon solvent is a mixture of n-alkanes having 5 to 12 carbon atoms and structural isomers of saturated or unsaturated hydrocarbons having 8 carbon atoms It is preferable to use a cyclic hydrocarbon having 5 to 7 carbon atoms. The polyfunctional acyl halide-containing solution preferably dissolves 0.01 to 2% by weight, more preferably 0.05 to 0.3% by weight, of the polyfunctional acyl halide in the aliphatic hydrocarbon solvent. In forming the polyamide layer of the present invention, the polyfunctional acid halide compound may be applied to the membrane treated with the aqueous solution containing the polyfunctional amine for 0.1 to 10 minutes, more preferably for 0.5 to 1 minute.

The reverse osmosis membrane according to the present invention produced by the above-described production method comprises a support, a porous polymeric support layer formed on at least one side of the support, and a polyamide layer formed on the polymeric support layer, . In order to avoid duplication, description of the same parts as those described in the above-described manufacturing method will be omitted.

The reverse osmosis membrane may have a permeate flow rate of 17 GFD or more and a salt removal rate of 99.4% or more at 25 ° C and 225 psi for an aqueous sodium chloride solution having a concentration of 2,000 ppm.

Also, for organic materials, IPA removal rate of 86% or more can be obtained at 25 ° C and 225 psi for isopropyl alcohol aqueous solution having a concentration of 1,000 ppm.

Meanwhile, the present invention implements a reverse osmosis module including the reverse osmosis membrane according to the present invention. As a non-limiting example, the reverse osmosis membrane may be wound into a porous permeable effluent tube in a spiral wound with spacers for flow path formation, and the amount of wound membrane And an end cap for shape stability of the membrane wound on the end. The material, shape, and size of the spacer and end cap can be spacers and end caps used in conventional reverse osmosis modules. The reverse osmosis membrane thus wound may be housed in an outer case, and the material, size, and shape of the outer case may be the material, size, and shape of the outer case used in a conventional reverse osmosis module.

In addition, the reverse osmosis module according to a preferred embodiment of the present invention may include the reverse osmosis membrane according to the present invention wound around the porous permeate outlet tube in a spiral shape in the outer case.

Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples are provided to illustrate the present invention, but the scope of the present invention is not limited by the following examples.

[ Example ]

Example  1. Preparation of reverse osmosis membrane.

A 18 wt% solution of dimethylformamide and polysulfone was cast on a polyester nonwoven fabric to a thickness of about 125 +/- 10 mu m and immediately subjected to phase transformation by immersing it in distilled water at 25 DEG C and then washed thoroughly with a nonwoven fabric reinforced polysulfone microporous substrate Subsequently, the solvent and water in the substrate were replaced and stored in pure water at room temperature. Then, the resultant was immersed in a first solution containing metaphenylene diamine and metaphenylenediamine having a concentration of 2.5% by weight and a compound represented by the following formula 2 having a weight part as shown in the following Table 1 for 60 seconds, The water layer was removed. Thereafter, the mixture was immersed in a second solution containing 0.07% by weight of trimesoyl chloride for 60 seconds to perform interfacial polymerization and dried at 60 DEG C for 1 minute and 30 seconds to form a polyamide layer. Then, 0.2 wt. % Sodium carbonate solution for 2 hours to prepare a reverse osmosis membrane.

(2)

Example  2 to 8.

The reverse osmosis membrane was prepared in the same manner as in Example 1, except that the concentration of Chemical Formula 2 was changed as shown in Table 1 below.

Example  9.

A reverse osmosis membrane was prepared in the same manner as in Example 1, except that the compound represented by the following formula (3) was used instead of the compound of the formula (2) in the concentrations shown in Table 1 below.

(3)

Example  10 to 16.

The reverse osmosis membrane was prepared in the same manner as in Example 9, except that the concentration of Chemical Formula 3 was changed as shown in Table 1 below.

Comparative Example  One.

The reverse osmosis membrane was prepared in the same manner as in Example 1 except that the second solution containing the chemical formula 2 or 3 was not treated as shown in Table 1 below.

[Experimental Example]

The performance of the reverse osmosis membrane prepared according to Examples 1 to 20 and Comparative Example 1 was evaluated and is shown in Table 2 below. The performance of the reverse osmosis membrane was measured at 25 ° C and 225 psi at a concentration of 2,000 ppm. The isopropyl alcohol performance was measured at 25 ° C and 225 ° C, psi, and the concentration of isopropyl alcohol was measured using liquid chromatography (HPLC).

Referring to Table 1, in the case of the reverse osmosis membrane according to Examples 1 to 16 prepared by including the polyfunctional amine compound in the first solution and the compound represented by the formula 2 or 3, The salt removal rate, and the IPA removal rate are superior to those of Comparative Example 1, which was prepared without the above-mentioned catalyst.

In particular, in the case of Examples 2 to 7 including the compound represented by Formula 2 of the present invention, wherein Formula 2 is 0.04 to 50 parts by weight based on 100 parts by weight of the polyfunctional amine compound, It can be seen that the salt removal rate or IPA removal rate exhibits comparatively excellent characteristics while showing a flow rate higher than a certain level as compared with Examples 1 and 8 which are included or exceeded by the numerical range of the present invention.

Similarly, in the case of Examples 10 to 15 including the compound represented by Formula 3 of the present invention, wherein Formula 3 is included in 0.04 to 50 parts by weight based on 100 parts by weight of the polyfunctional amine compound, It can be seen that the compound exhibits a flow rate higher than a certain level compared to Examples 9 and 16 in which the compound is contained in an amount of less than or greater than the value of the present invention, and exhibits relatively excellent salt removal rate or IPA removal rate.

In the case of Examples 4 to 6 and Examples 12 to 14 in which the formula (2) or (3) satisfies the preferred numerical range of 3 to 30 parts by weight of the present invention, It can be seen that the salt removal ratio and the IPA removal ratio are remarkably superior to those in the examples of the present invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. It will be obvious to the person. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

Claims (10)

(1) treating a polymer solution on at least one surface of a support to form a porous polymer support layer;
(2) a first solution containing a polyfunctional amine compound and a compound represented by the following formula (1) is added to the polymer support layer and then contacted with a second solution containing a polyfunctional acid halide compound to form an amine Forming a polyamide layer comprising a compound; Gt; A method for preparing a high salt rejection reverse osmosis membrane.
[Chemical Formula 1]

R ₁ , R ₂ and R ₃ are an alkyl group or an isomer thereof having a weight average molecular weight of 100 to 5000 and a carbon number of 1 to 18. The method according to claim 1,
Wherein the first solution of step (2) comprises any one of compounds represented by the following general formula (2) or (3).
(2)

(3)

The method according to claim 1,
Wherein the compound represented by Formula 1 is contained in the first solution in an amount of 0.04 to 50 parts by weight based on 100 parts by weight of the polyfunctional amine compound. The method of claim 1, wherein the step (2)
The polymer support layer is immersed in a first solution containing a polyfunctional amine compound and a compound represented by the following formula (1) for 5 to 600 seconds and brought into contact with a second solution containing a polyfunctional acid halide compound to form And forming a polyamide layer containing an amine compound on the surface of the reverse osmosis membrane. The method according to claim 1,
The polymer solution in step (1) may be at least one selected from the group consisting of polysulfone polymers, polyamide polymers, polyimide polymers, polyester polymers, olefin polymers, polyvinylidene fluoride, polybenzimidazole polymers, and polyacrylonitrile Wherein the at least one polymer material is selected from the group consisting of: The method according to claim 1,
The polymer solution in step (1) may be any one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO), or dimethylacetamide Or more of the solvent. The method according to claim 1,
The polyfunctional amine compound in the step (2) may be at least one selected from the group consisting of metaphenylenediamine, paraphenylenediamine, orthophenyldiamine, and dimethylenepiperazine, and a high salt rejection reverse osmosis membrane Way. The method according to claim 1,
The polyfunctional acid halide compound of step (2) may be at least one compound selected from the group consisting of trimesoyl chloride, isophthaloyl chloride, tepaloyl chloride, 1,3,5-cyclohexanetricarbonyl chloride and 1,2,3,4-cyclohexane Tetracarbonyl chloride. The method for producing a high salt rejection reverse osmosis membrane according to claim 1, A support;
A porous polymeric support layer formed on at least one side of the support; And
A polyamide layer formed on the polymer support layer; / RTI >
Wherein the polyamide layer comprises a polyfunctional amine compound and a formylated amine compound formed by reacting the polyfunctional amine compound represented by Formula 1 below.
[Chemical Formula 1]

R ₁ , R ₂ and R ₃ are an alkyl group or an isomer thereof having a weight average molecular weight of 100 to 5000 and a carbon number of 1 to 18. A reverse osmosis module comprising a reverse osmosis membrane according to claim 9.