KR20120022414A - Fouling resistance polyamide reverse osmosis membrane and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A polyamide reverse osmosis membrane and a method for manufacturing the same are provided to improve antifouling property to hydrophobic and/or hydrophilic organic materials by forming a hydrophobic coating layer on a polyamide layer. CONSTITUTION: A polyamide reverse osmosis membrane includes a microporous supporting layer, a polyamide layer, and a hydrophobic coating layer. The polyamide layer is formed on the microporous supporting layer. The hydrophobic coating layer is formed on the surface of the polyamide layer based on the covalent bond of hydrophobic compounds. The hydrophobic compounds are at least one primary amine or binary amine and include aliphatic alcohol compound with a non-terminal hydroxyl group with alkoxy group which is substituted with at least three fluorine.

Description

Polyamide reverse osmosis membrane with improved fouling resistance and its manufacturing method {FOULING RESISTANCE POLYAMIDE REVERSE OSMOSIS MEMBRANE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a polyamide reverse osmosis membrane having improved stain resistance and a method for producing the same, and more particularly, to a microporous support layer; A polyamide layer on the microporous support; And a hydrophobic coating layer in which a hydrophobic compound is covalently bonded to the surface of the polyamide layer, thereby forming a poly-improved fouling resistance against contaminants caused by hydrophobic and / or hydrophilic organics in high concentration seawater conditions. Amide reverse osmosis membrane and its manufacturing method.

In general, dissociated material can be separated from its solvent using various types of selective membranes. When the selective separation membranes are described in increasing order of pore size, they are classified into reverse osmosis membranes, ultrafiltration membranes, and microfiltration membranes.

The conventional use of reverse osmosis membrane is a desalination process of semi-saline or seawater, and this desalting process provides a large amount of fresh water or pure water, which is relatively suitable for industrial, agricultural, or household use. Demineralization of semi-saline or seawater using a reverse osmosis membrane is a process that literally filters salts and other dissolved ions or molecules from the brine, by purifying the brine through the reverse osmosis membrane, where purified water passes through the membrane while Dissolved ions or molecules do not pass through the membrane. Osmotic pressure is inevitably generated in the reverse osmosis process, and the higher the concentration of the raw water, the greater the osmotic pressure, and thus, a higher pressure is required to treat it.

Thus, in order for the reverse osmosis membrane to be used for commercially desalting large quantities of brine and seawater, there are several conditions to be provided, one of which has a high salt rejection rate. At least 97% or more of salt rejection of reverse osmosis membranes for semi-saline for commercial applications is currently required.

Another important property of reverse osmosis membranes is the ability to pass relatively large amounts of water through the membrane even at relatively low pressures, ie high flow rate characteristics. In general, the permeate flux of membranes is required at least 10 gallon / ft ² -day (gfd) at 800 psi for seawater and at least 15 gfd at 220 psi for brine. Depending on the application, permeate flow rates higher than the salt rejection rate are important, or vice versa.

One common type of reverse osmosis membrane is a composite membrane consisting of a microporous support and a polyamide thin film formed on the microporous support. The polyamide thin film is formed by interfacial polymerization of a polyfunctional amine and a polyfunctional acyl halide.

Representatively, US Pat. No. 4,277,344 to Cadette discloses aromatic polyamide complexes obtained by interfacial polymerization between an aromatic polyamine containing at least two primary amine substituents and an aromatic acyl halide having at least three acyl halide substituents. A film is disclosed. In a preferred embodiment, after coating the microporous polysulfone support with metaphenylenediamine dissolved in water, excess metaphenylenediamine solution is removed from the coated microporous support, and the coated support is Freon (FREON). ) Contact with a solution of trimesoylchloride dissolved in a TF solvent (trichlorotrifluoroethane). At this time, the contact time for the interfacial polymerization reaction is 10 seconds, the substantial reaction is completed in 1 second. The resulting polysulfone / polyamide composite membrane is dried in air.

The membranes disclosed by the catheter described above show good permeate flux and salt rejection. Various attempts have been made to increase the permeate flow rate of polyamide reverse osmosis composite membranes and to further improve salt rejection. On the other hand, research has been conducted in an attempt to improve the chemical resistance of the membrane in addition to the permeability of the membrane, most of the research has been the main method of using various types of additives in the solution used in the interfacial polycondensation reaction.

Specifically, examples of forming an additive by adding an additive to a solution used in an interfacial polycondensation reaction include U.S. Patent Nos. 4,983,291 to Chau et al. And U.S. Patent Nos. 5,576,057 to U.S. Pat. And U. S. Patent No. 5,614, 099, U. S. Patent No. 6,245, 234, U. S. Patent No. 6,063, 278, and U. S. Patent No. 6,015, 495, all of which are disclosed by Tran et al. It describes as.

As another example, according to US Patent No. 5,178,766 by Ikeda, in order to improve the separation performance of the reverse osmosis membrane, to covalently bond the quaternary amine to the surface of the polyamide thin film formed by interfacial polymerization The quaternary amines used were shown to have an epoxy group, an aziridine group, an episulfide group, a halogenated alkyl group, an amino group, a carboxyl group, a halogenated carbonyl group, and a hydroxy group as a reactor with the surface.

As described above, a variety of attempts have been made to improve the performance of polyamide composite membranes. However, reverse osmosis membranes having excellent chemical resistance and excellent separation performance and permeability have been proposed, but the problem of membrane contamination in membrane properties still has not been solved. As pointed out.

That is, fouling of the membrane means that suspended solids or dissolved substances adsorb or adhere to the membrane surface, resulting in a decrease in permeate flow rate.

At this time, the fouling of the membrane is primarily generated by combining the surface of the membrane with a suspended or dissolved material in the solution filtered by hydrophobic bonds and electrostatic attraction.

In addition, in addition to the primary membrane fouling, microorganisms caused by organic or inorganic substances are adsorbed on the surface of the separator and then grown to form a bio-film on the surface of the separator. Such fouling of the membrane is not preferable because it impedes the permeation performance of the membrane and thus requires frequent correction of pressure or cleaning in case of serious fouling of the membrane to obtain a constant flow rate of permeate.

In an attempt to reduce conventional membrane contamination, Hachisuka (US Pat. No. 6,177,011) discloses contamination resistance to organics by recoating electrostatically neutral and hydrophilic polymers such as polyvinyl alcohol on the surface of polyamide composite membranes. It is reported that it can be increased.

As another attempt to solve the contamination problem of the membrane, US Pat. No. 6,280,853 to Mickols proposes a composite membrane consisting of a crosslinked polyamide surface containing polyalkylene oxide grafted on a porous support. In addition, it has reported an improvement in pollution resistance.

In addition, U.S. Patent No. 6,913,694, reported by Koo, discloses a selective separator having excellent fouling resistance by applying a hydrophilic coating to a polyamide layer. At this time, the hydrophilic coating is to apply a quantitative determination of the polyfunctional epoxy compound consisting of at least two epoxy groups to the separator, and then to cross-link the polyfunctional epoxy compound, to obtain a polymer insoluble in water.

However, various methods attempted to improve the stain resistance of the related art require improvement of the stain resistance to be applied to high concentrations of raw water conditions such as seawater as well as brine. Therefore, in order to improve fouling resistance in reverse osmosis membrane systems, chemical pretreatment processes such as physical pretreatment for removing particulates or bacteria through filtration or pH control, or a combination thereof are introduced. However, there is still a problem of contamination of the membrane by organic matter.

In general, the contaminants caused by organic matter in the membrane are the final decomposition products of general organisms, and there are sodium alginate present as components of brown algae such as humic acid, seaweed and kelp in nature. Humic acid is a representative hydrophobic membrane contaminant, and sodium alginate is a representative hydrophilic membrane contaminant, and resistance to the two substances is required to improve the fouling resistance to contaminants of organic matter.

It is an object of the present invention to provide a polyamide reverse osmosis membrane with improved fouling resistance.

Another object of the present invention is a microporous support layer; A polyamide layer on the microporous support; And forming a hydrophobic coating layer in which a hydrophobic compound is covalently bonded to the surface of the polyamide layer, thereby providing a method for preparing a polyamide reverse osmosis membrane having improved fouling resistance under high concentration of seawater as well as brine.

In order to achieve the above object, the present invention is a microporous support layer; A polyamide layer formed on the microporous support; And a hydrophobic coating layer in which a hydrophobic compound formed on the surface of the polyamide layer is covalently bonded to provide a polyamide reverse osmosis membrane having excellent fouling resistance.

In the hydrophobic coating layer characterized by the present invention, the hydrophobic compound is (i) at least one primary amine or secondary amine, and (ii) an aliphatic having a non-terminal hydroxy group including an alkoxy group substituted with at least three or more fluorine. It is a compound containing an alcohol compound.

As a preferable hydrophobic compound of this invention, it is a compound of linear structure, According to the structure of an alkoxy group, the compound represented by following General formula (1) is used.

(Wherein R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with three or more fluorine, and R 'is hydrogen or a fluorine atom.)

As another preferable hydrophobic compound of this invention, the compound represented by following formula (2) is used.

(Wherein R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with 3 or more fluorine, R 'is hydrogen or a fluorine atom, n is 1-8.)

Specific examples of preferred hydrophobic compounds of the present invention include 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol and 1-amino-3- (2,2,3,3 , 4,4-hexafluorobutoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol, 1- Amino-3- (2,2,3,3,4,4,5,5,6,6-decafluorohexyloxy) -2-propanol, 1-amino-3- (2,2,3,3 , 4,4,5,5,6,6,7,7-dodecafluoroheptoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5 , 6,6,7,7,8,8-tetradecafluorooctyloxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6,6 , 7,7,8,8,9,9-hexategafluorononyloxy) -2-propanol and 1-amino-3- (2,2,3,3,4,4,5,5,6, 6,7,7,8,8,9,9,10,10-octadecafluorodecyloxy) -2-propanol is to use any one selected from the group consisting of.

The present invention casts a polysulfone-containing solution on a nonwoven fabric to prepare a nonwoven fabric-reinforced microporous support layer, forms a polyamide layer by interfacial polymerization on the support layer, and coats a hydrophobic compound-containing solution on the polyamide layer surface. It provides a method for producing a polyamide reverse osmosis membrane to be covalently bonded to form a hydrophobic coating layer.

In the production method of the present invention, the hydrophobic compound-containing solution is an aqueous solution containing 0.0001 to 2% by weight of the hydrophobic compound, wherein the preferred hydrophobic compound includes a compound represented by the following formula (1) or (2).

Formula 1

(In the above, R and R 'are as defined above.)

Formula 2

(In the above, R, R 'and n are as defined above.)

In the preparation method of the present invention, the hydrophobic coating layer is formed by contacting the hydrophobic compound-containing solution on the surface of the polyamide layer at room temperature to 95 ° C. for 5 seconds to 10 minutes.

As described above, the present invention forms a polyamide layer on the microporous support layer, and includes a residual alkoxide group and an alkoxy group substituted with a hydrophobic fluorine when the polyamide layer is formed on the surface of the polyamide layer. It is possible to provide a polyamide reverse osmosis membrane having a hydrophobic coating layer formed by covalent bonding between aliphatic alcohol compounds including a primary amine group and a method of manufacturing the same.

In the polyamide reverse osmosis membrane of the present invention, hydrophobic compounds are covalently bonded to the polyamide layer to form a hydrophobic coating layer, thereby improving fouling resistance to contaminants caused by hydrophobic and / or hydrophilic organic substances, and particularly high concentrations such as seawater. Membrane fouling under raw water conditions can be prevented. Accordingly, the polyamide reverse osmosis membrane of the present invention is suitable for seawater desalination.

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

The present invention is a microporous support layer; A polyamide layer on the microporous support layer; And a hydrophobic coating layer in which a hydrophobic compound is covalently bonded to the surface of the polyamide layer.

The microporous support layer of the present invention serves as a support for the polyamide layer. In order to accomplish this object, the material of the microporous support of the present invention includes polysulfone, polyethersulfone, polyimide, polypropylen, and polyvinylidene fluoride. It is any one selected from the group consisting of halogenated polymers, wherein the pore size of the microporous support is preferably 1 to 500nm. More preferably, a nonwoven fabric-reinforced microporous support layer used by coating and drying the polymer-containing solution on a nonwoven fabric may be used.

The polyamide layer of the present invention is formed by interfacial polymerization using a material that reacts with a polyfunctional amine and a polyfunctional amine.

A feature of the present invention is to provide a polyamide reverse osmosis membrane having improved fouling resistance even in fresh water or high concentration of raw water conditions against hydrophobic and / or hydrophilic contaminants by forming a hydrophobic coating layer by covalently bonding a hydrophobic compound to the polyamide layer. will be.

The hydrophobic coating layer of the present invention is formed by a covalent bond between the reaction residue acid chloride and an aliphatic alcohol compound including a primary or secondary amine group containing alkoxy group substituted with hydrophobic fluorine when forming a polyamide layer.

In this case, the hydrophobic compound should include at least one reactive group directly covalently bonded to the polyamide layer, wherein the at least one reactive group is (i) at least one primary amine or secondary amine, (ii A compound comprising an aliphatic alcohol compound having a non-terminal hydroxy group containing an alkoxy group substituted with at least three fluorine.

Therefore, preferably, the hydrophobic compound of the present invention has a linear structure, and according to the structure of the alkoxy group, a compound represented by the following formula (1) is used.

Formula 1

Wherein R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with 3 or more fluorine, more preferably a methyl, ethyl, propyl, butyl or trifluoroethyl group, and R 'is hydrogen Or a fluorine atom.

In addition, it is to use a hydrophobic compound represented by the formula (2) of the present invention.

Formula 2

Wherein R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with 3 or more fluorine, more preferably a methyl, ethyl, propyl, butyl or trifluoroethyl group, and R 'is hydrogen Or a fluorine atom, n is 1-8.

As the hydrophobic compound used in the present invention, most preferably 1-amino-3- (1,1,2,2-tetrafluoroethoxy) -2-propanol, 1-amino-3- (2,2,3 , 3-tetrafluoropropoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4-hexafluorobutoxy) -2-propanol, 1-amino-3- (2 , 2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6, 6-decafluorohexyloxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptoxy) 2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6,6,7,7,8,8-tetradecafluorooctyloxy) -2-propanol , 1-amino-3- (2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexategafluorononyloxy) -2- Propanol and 1-amino-3- (2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-octadecafluorodecyl C) -2-propanol can be used any one selected from the group consisting of.

In the polyamide reverse osmosis membrane of the present invention, hydrophobic compounds are covalently bonded to the polyamide layer to form a hydrophobic coating layer, thereby improving fouling resistance to hydrophobic and / or hydrophilic contaminants, in particular, at 25 ° C., 800 psi, and pH 8.0. Under high concentration of raw water with an overconcentration of 32,000 ppm, the fouling resistance is significantly improved compared to a conventional polyamide reverse osmosis membrane without a hydrophobic coating layer. Therefore, the polyamide reverse osmosis membrane of the present invention can prevent the membrane fouling phenomenon occurring under high concentration of raw water conditions such as seawater, and thus can be applied as a seawater desalination membrane.

In addition, the present invention is to prepare a nonwoven fabric reinforced polysulfone microporous support layer by casting a polysulfone-containing solution on the nonwoven fabric,

Forming a polyamide layer by interfacial polymerization on the support layer,

It provides a polyamide reverse osmosis membrane to form a hydrophobic coating layer by coating a hydrophobic compound-containing solution on the surface of the polyamide layer to be covalently bonded.

The polyamide layer of the present invention is formed by a method of forming a film by interfacial polymerization using a polyfunctional amine and a material reacting with the polyfunctional amine. That is, a polyfunctional amine is applied onto the microporous support layer, and the excess solution is removed, followed by contact reaction with an organic solution containing a polyfunctional halogen compound to form a polyamide layer.

The polyfunctional amine is a polyamine comprising a primary amine or a secondary amine as a substance having 2-3 amine functional groups per monomer. In this case, as polyamines, aromatic primary diamines are used as metaphenylenediamine, paraphenylenediamine, and substituents, and as another example, cycloaliphatic primary diamines such as aliphatic primary diamines and cyclohexene diamines, such as piperazine Cycloaliphatic secondary amines, aromatic secondary amines and the like can be used.

More preferably, metaphenylenediamine is used in the polyfunctional amine, and in this case, the concentration is preferably in the form of an aqueous solution containing 0.5 to 10% by weight of metaphenylenediamine, and more preferably 1 to 4 metaphenylenediamine. % By weight.

When forming the polyamide layer of this invention, the said polyfunctional amine containing aqueous solution is apply | coated for 0.1 to 10 minutes on a microporous support body, More preferably, it is immersed for 0.5 to 1 minute.

In addition, a polyfunctional acid halogen compound, i.e., a polyfunctional acyl halide, is used as a material to react with the polyfunctional amine used in forming the polyamide layer of the present invention. Examples thereof include trimezoyl chloride, isophthaloyl chloride, terephthaloyl chloride and the like can be used alone or in a mixed form. In this case, the use of the mixed form is most preferable in terms of salt removal rate.

The polyfunctional acyl halide should be dissolved in an aliphatic hydrocarbon solvent at 0.01 to 2% by weight, and 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. Preference is given to using cyclic hydrocarbons having 5 to 7 carbon atoms.

It is preferable that 0.01-2 weight% of polyfunctional acyl halides melt | dissolve in an aliphatic hydrocarbon solvent, and, as for the said polyfunctional acyl halide containing solution, 0.05-0.3 weight% is more preferable. In this case, the polyfunctional acid halogen compound may include a single form or a mixture of two or more kinds.

The hydrophobic coating layer of the present invention is formed by covalently bonding a hydrophobic compound on the surface of the polyamide layer, and after immersing in the prepared polyfunctional acid halide compound-containing solution for 1 to 3 minutes, the prepared membrane is characterized by the present invention. The aqueous solution containing the phosphoric hydrophobic compound is contacted by impregnation or spray for 5 seconds to 10 minutes, more preferably 20 seconds to 4 minutes at room temperature to 95 ° C., to form a hydrophobic coating layer on the polyamide separator. In this case, the hydrophobic compound is covalently bonded to the polyamide separator through the reaction between the primary and secondary amino groups and the residual acid chloride of the polyamide separator.

The resulting separator is washed with a basic aqueous solution such as 0.2% by weight sodium carbonate at room temperature to 95 ° C. for 1 to 30 minutes and then washed with distilled water to remove impurities and unreacted residues on the surface.

As described above, the hydrophobic coating layer of the present invention is formed by covalently bonding a hydrophobic compound to the remaining acid chloride of the polyamide separation membrane.

Accordingly, the hydrophobic compound of the present invention should include at least one reactive group directly covalently bonded to the polyamide layer, wherein the at least one reactive group is (i) at least one primary amine or secondary amine, (ii) an aliphatic alcohol compound having a non-terminal hydroxy group containing an alkoxy group substituted with at least three or more fluorine.

More preferably, the hydrophobic compound of the present invention uses a compound having a linear structure represented by the following formula (1) or (2), depending on the structure of the alkoxy group.

Formula 1

(In the above, R and R 'are as defined above.)

Formula 2

(In the above, R, R 'and n are as defined above.)

More preferably, examples of the hydrophobic compound of the present invention include 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol and 1-amino-3- (2,2,3 , 3,4,4-hexafluorobutoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6,6-decafluorohexyloxy) -2-propanol, 1-amino-3- (2,2,3 , 3,4,4,5,5,6,6,7,7-dodecafluoroheptoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5 , 5,6,6,7,7,8,8-tetradecafluorooctyloxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6 , 6,7,7,8,8,9,9-hexategafluorononyloxy) -2-propanol and 1-amino-3- (2,2,3,3,4,4,5,5, Any one selected from the group consisting of 6,6,7,7,8,8,9,9,10,10-octadecafluorodecyloxy) -2-propanol can be used.

The hydrophobic compound of the present invention is in contact with the polyamide layer with an aqueous solution containing the same. In this case, an aqueous phase containing 0.0001 to 2% by weight, more preferably 0.001 to 1% by weight is preferable. When the concentration of the hydrophobic compound exceeds 2% by weight, the permeation flow rate is drastically reduced, so that the commercially required physical properties of the polyamide composite membrane cannot be satisfied.

In addition, the aqueous solution containing a hydrophobic compound is brought into contact with the surface of the polyamide layer by impregnation or spray for 5 seconds to 10 minutes, more preferably 20 seconds to 4 minutes, at room temperature to 95 ° C. To form a hydrophobic coating layer.

The polyamide reverse osmosis membrane prepared by the preparation method of the present invention was operated at 25 ° C., 800 psi, pH 8.0, and in an aqueous solution of sodium chloride (NaCl) at a concentration of 32,000 ppm for 2 hours, and the performance was measured. ppm Flow Rate Reduction (%) was below 7.0% in a mixed aqueous solution composed of 10 ppm humic acid / 2 ppm calcium chloride or a mixed aqueous solution composed of 32,000 ppm sodium chloride / 10 ppm sodium alginate / 2 ppm calcium chloride Can be.

The result is a significantly reduced flow rate reduction rate compared to conventional polyamide reverse osmosis membranes without a hydrophobic coating layer, in particular, it can be confirmed that the fouling resistance to contaminants caused by hydrophilic organic matter. Accordingly, the polyamide reverse osmosis membrane of the present invention can prevent the membrane fouling phenomenon occurring in high concentration raw water conditions such as seawater as well as salt water.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

≪ Example 1 >

On a polyester nonwoven fabric, a 18 wt% polysulfone containing dimethylformamide solution was cast to a thickness of about 125 ± 10 μm, immediately immersed in distilled water at 25 ° C. for phase change, and then the nonwoven reinforced polysulfone microporous substrate. Was washed with water sufficiently to replace the solvent and water in the substrate, and then stored in pure water at room temperature. After immersion for 1 minute in an aqueous solution containing metaphenylenediamine at a concentration of 3.0% by weight, the water layer on the surface was removed by a compression method. The substrate was immersed in an organic solution containing 0.07% by weight of trimezoyl chloride and 0.1% by weight of isophthaloyl chloride for 1 minute, followed by interfacial polymerization, followed by natural drying at room temperature (25 ° C.) for 1 minute and 30 seconds to form a polyamide layer. Formed.

Immediately after the polyamide layer was formed, it was immersed in an aqueous solution of 0.01% by weight of 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol for 2 minutes, followed by 0.2% by weight of sodium carbonate solution. It was immersed for 2 hours to prepare a polyamide film in which unreacted residues were removed and a hydrophobic coating layer was formed.

<Example 2>

Immediately after formation of the polyamide layer as in Example 1, except that it was immersed in 0.05% by weight of 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol aqueous solution for 2 minutes. Was performed in the same manner as in Example 1 to prepare a polyamide film having a hydrophobic coating layer.

<Example 3>

Immediately after formation of the polyamide layer as in Example 1, except that it was immersed in 0.1% by weight of 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol aqueous solution for 2 minutes. Was performed in the same manner as in Example 1 to prepare a polyamide film having a hydrophobic coating layer.

<Example 4>

In the same manner as in Example 1, immediately after the polyamide layer was formed, 0.01% by weight of 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol aqueous solution Except immersing for 2 minutes in the same manner as in Example 1 to prepare a polyamide film having a hydrophobic coating layer.

Example 5

Immediately after formation of the polyamide layer as in Example 1, 0.05% by weight of 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol aqueous solution Except immersing for 2 minutes in the same manner as in Example 1 to prepare a polyamide film having a hydrophobic coating layer.

<Example 6>

Immediately after formation of the polyamide layer as in Example 1, 0.1% by weight of 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol aqueous solution Except immersing for 2 minutes in the same manner as in Example 1 to prepare a polyamide film having a hydrophobic coating layer.

Comparative Example 1

It was immersed in the aqueous solution of metaphenylenediamine in the same manner as in Example 1. This was immersed in an organic solution containing 0.07% by weight of trimezoyl chloride and 0.1% by weight of isophthaloyl chloride for 1 minute, followed by interfacial polymerization, and then unreacted residues were immediately removed without being immersed in an aqueous hydrophobic compound solution. The membrane was prepared.

Experimental Example 1

For the separation membranes obtained in Examples 1 to 6 and Comparative Example 1 described above, the contact angle measurement results are described in Table 1 below in order to measure the presence and degree of hydrophobicity of the secondary coated membrane.

As can be seen in Table 1, the polyamide membrane of Examples 1-6 coated on the polyamide layer obtained by interfacial polymerization was significantly hydrophobic compared to Comparative Example 1, 1-amino used in the second coating -3- (2,2,3,3-tetrafluoropropoxy) -2-propanol and 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) As the concentration of -2-propanol increased, the degree of hydrophobicity of the surface of the polyamide membrane increased.

Experimental Example 2

The performance of the polyamide membranes obtained in Examples 1 to 6 and Comparative Example 1 was evaluated in the presence of humic acid as a contaminant and the results are shown in Table 2 below.

Experimental Example 3

The performance of the polyamide membranes obtained in Examples 1 to 6 and Comparative Example 1 described above was evaluated in the presence of sodium alginate as a contaminant and the results are shown in Table 3 below.

From the results of Tables 2 and 3, it was confirmed that the polyamide membrane of Comparative Example 1, which was not coated with a hydrophobic material, had a similarly high flow rate reduction rate for the two substances of humic acid and sodium alginate as pollutants.

On the other hand, the polyamide membrane prepared in Examples 1 to 6 satisfies the level at which the flow rate and salt excretion rate measurements are commercially available, and in particular, with respect to the two materials of humic acid and sodium alginate compared to the polyamide membrane of Comparative Example 1, Both the flow rate reduction rate improved. In particular, it showed a significantly improved flow rate reduction rate for sodium alginate than humic acid. These results indicate that humic acid is hydrophobic, but changes hydrophilic with increasing pH, so it is expected to be less effective than hydrophilic sodium alginate because it exists in two types of hydrophilic and hydrophobic at about pH 8.0. Can be.

According to the results of Tables 2 and 3, it was confirmed that the polyamide layer obtained through the interfacial polymerization contributes to the improvement of fouling resistance according to the hydrophobic concentration of the second coating material.

Therefore, according to the present invention contributes to the improvement of fouling resistance according to the degree of hydrophobicity of the hydrophobic compound formed in the polyamide layer obtained through interfacial polymerization, that is, the greater the number of fluorine contained in the compound used in forming the hydrophobic coating layer, The higher the concentration of was confirmed that the fouling performance is improved.

As described above, the present invention forms a polyamide layer on the microporous support layer, and when the polyamide layer is formed on the surface of the polyamide layer, a hydrophobic coating layer is formed by the covalent bond between the reaction residual acid chloride and the hydrophobic compound. The contamination resistance is improved for contaminants caused by hydrophilic organic substances, and in particular, it is possible to fundamentally prevent membrane fouling occurring under conditions of pH 8.0 and high concentration of raw water such as seawater. Accordingly, the polyamide reverse osmosis membrane of the present invention is suitable for seawater desalination.

In addition, the present invention is to prepare a non-woven fabric reinforced fine porous support layer by casting a polysulfone-containing solution on a nonwoven fabric, to form a polyamide layer by interfacial polymerization on the support layer, a solution containing a hydrophobic compound on the surface of the polyamide layer The present invention provides a method for preparing a polyamide reverse osmosis membrane which is coated and covalently bonded to form a hydrophobic coating layer.

While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

Microporous support layer;
A polyamide layer formed on the microporous support; And
A polyamide reverse osmosis membrane having improved fouling resistance consisting of a hydrophobic coating layer in which a hydrophobic compound formed on the surface of the polyamide layer is covalently bonded. The method of claim 1 wherein the hydrophobic compound is
(i) at least one primary amine or secondary amine,
(ii) wherein said polyamide reverse osmosis membrane is a compound comprising an aliphatic alcohol compound having a non-terminal hydroxy group containing an alkoxy group substituted with at least three fluorine. The polyamide reverse osmosis membrane according to claim 1, wherein the hydrophobic compound is a compound represented by the following Chemical Formula 1:
Formula 1

Wherein R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with three or more fluorine, and R 'is hydrogen or a fluorine atom. The polyamide reverse osmosis membrane according to claim 1, wherein the hydrophobic compound is a compound represented by the following Chemical Formula 2:
Formula 2

In the above, R is a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkyl group substituted with three or more fluorine, R 'is hydrogen or a fluorine atom, n is 1-8. The method of claim 1, wherein the hydrophobic compound is 1-amino-3- (2,2,3,3-tetrafluoropropoxy) -2-propanol, 1-amino-3- (2,2,3,3, 4,4-hexafluorobutoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5-octafluoropentoxy) -2-propanol, 1-amino -3- (2,2,3,3,4,4,5,5,6,6-decafluorohexyloxy) -2-propanol, 1-amino-3- (2,2,3,3, 4,4,5,5,6,6,7,7-dodecafluoroheptoxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5, 6,6,7,7,8,8-tetradecafluorooctyloxy) -2-propanol, 1-amino-3- (2,2,3,3,4,4,5,5,6,6, 7,7,8,8,9,9-hexategafluorononyloxy) -2-propanol and 1-amino-3- (2,2,3,3,4,4,5,5,6,6 The polyamide reverse osmosis membrane, characterized in that any one selected from the group consisting of, 7,7,8,8,9,9,10,10-octadeca fluordecyloxy) -2-propanol. Casting a polysulfone-containing solution on the nonwoven fabric to prepare a nonwoven reinforced microporous support layer,
Forming a polyamide layer by interfacial polymerization on the support layer,
A method for producing the polyamide reverse osmosis membrane of claim 1, wherein the polyamide layer is coated with a hydrophobic compound-containing solution to covalently bond to form a hydrophobic coating layer. The method according to claim 6, wherein the hydrophobic compound-containing solution is an aqueous solution containing 0.0001 to 2% by weight of a hydrophobic compound. The method according to claim 7, wherein the hydrophobic compound is a compound represented by the following formula (1):
Formula 1

In the above, R, R 'are as defined in claim 3. The method according to claim 7, wherein the hydrophobic compound is a compound represented by the following formula (2):
Formula 2

In the above, R, R 'and n are as defined in claim 4. The method of claim 6, wherein the hydrophobic coating layer is formed on the surface of the polyamide layer by contact with a hydrophobic compound-containing solution at room temperature to 95 ° C. for 5 seconds to 10 minutes.