KR20140004298A - Forward osmosis membrane and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a forward osmosis membrane and a manufacturing method thereof, more specifically to: a forward osmosis membrane which offers high water permeability and flow rate toward the osmosis direction by smoothly flowing water from raw water to an induced solution by improving porosity and optimizing a pore structure, secures contamination resistance and chemical resistance by effectively coating a polyamide layer on the surface of a supporting layer and improving the combination degree between the polyamide layer and the supporting layer, and minimizes the reverse diffusion of a solute in the induced solution to the reverse osmosis direction; and a manufacturing method thereof.

Description

Technical Field The present invention relates to a positive osmosis membrane and a manufacturing method thereof,

More particularly, the present invention relates to a purified osmosis membrane and a method for producing the osmosis membrane, and more particularly, to an osmosis membrane having a high water permeability and excellent stain resistance, To a reverse osmosis membrane, and to a method of manufacturing the same.

The cleansing membrane is separated by moving osmotic pressure generated by the concentration difference between the two solutions to the high concentration solution through the membrane using the osmotic pressure as a driving force.

 Therefore, the osmosis membrane should allow water to flow from the raw water to the inducing solution through the membrane, while maintaining a constant concentration of the inducing solute while maintaining a high osmotic pressure. For this purpose, it is most important that the osmosis membrane has a high water permeability in the osmotic direction and that the solute of the inducing solution is not diffused in the reverse osmosis direction. In addition, the manufacture of the osmosis membrane having less membrane contamination should be preceded. Hereinafter, the characteristics of the osmosis membrane should be summarized as follows.

 First, in order to minimize the internal concentration polarization and increase the stain resistance, the porosity of the support layer in the quasi-osmosis membrane should be high and the pore bending degree should be low.

 Second, in order to increase the flow rate of permeated water, the thickness of the osmosis membrane should be minimized.

 Third, a hydrophilic material is used to minimize permeation resistance to water.

 Fourth, in order to maintain the induction solution at a high concentration, solutes should not diffuse from a high concentration solution to a low concentration solution.

Conventionally, there has been proposed a method for producing a positive osmosis membrane using cellulose triacetate which is a hydrophilic material. More specifically, a solution of cellulose acetate triacetate in a concentration of 8 to 18 탆 (FO) mode using an induction solution, and a high flow rate of the osmosis membrane at a flow rate of 11 gfd. However, it has been reported that the membrane prepared above has a disadvantage in that the induction solution of high concentration diffuses the solute in the direction of the low concentration of raw water. In the raw water condition containing a high concentration of salt such as seawater, Which is difficult to apply in practice.

The polyamide reverse osmosis membrane is prepared by interfacial polymerization of a polyfunctional amine and a polyfunctional acid halide compound on the surface of the membrane prepared by casting a polysulfone solution on a nonwoven fabric by previously casting a polysulfone solution at the level of an ultrafiltration membrane, The membrane was removed and applied to the FO system. As a result of evaluating the physical properties of the membrane in a forward osmosis (FO) mode, a forward osmosis membrane having a salt removal rate of 0.5 gfd and a salt removal rate of 99% or more was proposed. However, the above-mentioned osmosis membrane has a salt removal rate sufficient to separate high-concentration raw water such as seawater, but has a low flow rate and thus has a problem that the use of the membrane is limited in practice.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a honeycomb structure in which a polyamide layer is more efficiently coated on a quasi-osmosis membrane support layer, The goal is to minimize things.

In order to solve the above problems, the present invention,

(1) forming a polymer support layer by doping a polymer solution on a nonwoven fabric layer; (2) a step of plasma-treating the surface of the polymer support layer to introduce a hydrophilic radical; And (3) immersing the polymer support layer in an aqueous solution containing a polyfunctional amine, and then contacting the polymer support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer. And a manufacturing method thereof.

According to a preferred embodiment of the present invention, the polymer 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, a polybenzimidazole polymer, polyvinylidene fluoride, and poly Acrylonitrile, acrylonitrile, and acrylonitrile.

According to another preferred embodiment of the present invention, the polymer solution of step (1) may include 0.1 to 7 parts by weight of the sulfonated polysulfone-based polymer per 100 parts by weight of the solvent.

According to another preferred embodiment of the present invention, the plasma surface treatment of the step (2) is ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), oxygen (O ₂ ), nitrogen (N ₂ ), sulfuric acid (H Any one or more gases or liquids selected from the group consisting of ₂ SO ₄ ) and water (H ₂ O) can be used.

According to another preferred embodiment of the present invention, the plasma surface treatment of step (2) may be a discharge treatment for 10 to 600 seconds to 100 to 1000W.

The present invention relates to a polymeric support layer; And a polyamide layer formed on one surface of the polymer support layer, wherein the surface of the polymer support layer facing the polyamide layer is subjected to plasma treatment to be hydrophilic surface-modified.

The present invention also relates to a polymeric support layer; And a polyamide layer formed on one surface of the polymer support layer, wherein the polymer support layer has a contact angle of 45 ° or less and an initial wettability of 70% or more.

According to a preferred embodiment of the present invention, the polymeric support layer may be formed on the nonwoven fabric layer.

According to another preferred embodiment of the present invention, the polymer support layer may be formed of a polymer such as polysulfone polymer, polyamide polymer, polyimide polymer, polyester polymer, olefin polymer, polybenzimidazole polymer, polyvinylidene fluoride And polyacrylonitrile. ≪ IMAGE >

According to another preferred embodiment of the present invention, the polymer support layer may contain 0.5 to 15% by weight of a sulfonated polysulfone-based polymer.

According to another preferred embodiment of the present invention, the polymer support layer has a porosity of 30 to 80%, and may include finger-like macropores having a long axis of 1 to 100um and a short axis of 0.1 to 6um.

According to another preferred embodiment of the present invention, the plasma-treated support layer may have a contact angle of 45 ° or less and an initial wettability of 70% or more.

According to another preferred embodiment of the present invention, the thickness of the polymer support layer is 30 to 250um, the thickness of the polyamide layer may be 0.01 to 1um.

The present invention can optimize the pore structure and improve porosity so that water can flow smoothly from the raw water to the induction solution, thereby realizing high water permeability and flow rate in the osmotic direction.

Further, by more efficiently coating the polyamide layer on the surface of the support layer and increasing the degree of bonding between the support layer and the polyamide layer, the stain resistance and chemical resistance are ensured and the solute in the induction solution is despread in the reverse osmosis direction Can be minimized.

 FIG. 1 is a cross-sectional view of a positive osmosis membrane according to a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings.

 As described above, the conventional osmosis membrane has the problem of despreading the solute of the inducing solution and securing the salt removal rate, but the water permeability and the flow rate are low.

 (1) forming a polymer support layer by doping a polymer solution on a nonwoven fabric layer; (2) a step of plasma-treating the surface of the polymer support layer to introduce a hydrophilic radical; And (3) immersing the polymer support layer in an aqueous solution containing a polyfunctional amine, and then contacting the polymer support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer. The present invention has been made to solve the above-mentioned problems by providing a manufacturing method.

By this, it is possible to optimize the pore structure and improve the porosity, thereby realizing high water permeability and flow rate, ensuring stain resistance and chemical resistance, and preventing reverse solubility of the solute in the induction solution in the reverse osmosis direction.

In the step (1), a polymer solution is doped on the nonwoven fabric layer to form a polymer support layer.

The nonwoven fabric layer is not particularly limited as long as it serves as a support of a membrane, but more preferably synthetic fibers selected from the group consisting of polyester, polypropylene, nylon and polyethylene; Or natural fibers including cellulosic fibers; And the nonwoven fabric layer can control the physical properties of the membrane according to porosity and hydrophilicity of the material.

The porosity of the nonwoven fabric layer may be used as long as it satisfies the air permeation amount of 2 cc / cm 2 sec or more, and more preferably as long as the material satisfies the air permeation amount of 2 to 20 cc / cm 2 sec. At this time, when the average pore size of the nonwoven fabric layer of the present invention is preferably 1 to 600 μm, and more preferably 5 to 300 μm, smooth permeation of water and water permeability required for the positive osmosis membrane can be improved. The thickness of the nonwoven fabric layer of the present invention is preferably 20 to 150 占 퐉. If the thickness is less than 20 占 퐉, the strength and supporting function of the entire membrane are insufficient.

The solvent for forming the polymer solution is not particularly limited as long as it can dissolve the polymer uniformly without forming precipitates, but is more preferably selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) Dimethylsulfoxide (DMSO) or dimethylacetamide (DMAc), or the like.

If the temperature is lower than 20 ° C, the polymer may not be dissolved and the membrane may not be produced. If the temperature is higher than 90 ° C, the viscosity of the polymer solution may become too thin, and thus the membrane may be difficult to produce .

The polymer forming the polymer solution is not particularly limited as long as it can form a regular osmosis membrane. It is more preferable that the polymer forming the polymer solution is a polysulfone polymer, a polyamide polymer, a polyimide polymer, a polyester polymer, an olefin polymer , A polybenzimidazole polymer, polyvinylidene fluoride or polyacrylonitrile, and the like, alone or in combination.

The polymer solution may preferably contain 10 to 40 parts by weight of polymer based on 100 parts by weight of the solvent. When the amount of the polymeric substance is less than 10 parts by weight, the strength is lowered and the solution viscosity is low, which makes the membrane difficult to produce. When the amount exceeds 40 parts by weight, the desired phase transfer rate is affected, The concentration of the polymer solution is excessively high, which may make it difficult to produce the membrane.

The polymer solution may further comprise 0.1 to 7 parts by weight of a sulfonated polysulfone-based polymer per 100 parts by weight of the solvent. By further including the sulfonated polysulfone-based polymer, hydrophilicity can be imparted to the film to be formed and the phase separation rate can be controlled. When the sulfonated polysulfone polymer is less than 0.1 part by weight, the effect of improving hydrophilicity is insufficient. When the sulfonated polysulfone polymer is more than 7 parts by weight, the viscosity of the polymer solution may be lowered, thus making it difficult to form a film.

 In the step (2), the surface of the polymer support layer is subjected to a plasma surface treatment to introduce a hydrophilic radical.

 Conventionally, since the hydrophobic polymer, which is a main constituent of the polymer support layer, has low initial wettability, it is not easy to penetrate the amine aqueous solution during the production of the selective layer by the polyamide interfacial polymerization, so that the polyamide layer is effectively formed on the surface of the polymer support layer In the present invention, hydrophilicity radicals are introduced to the surface of the polymer support layer by plasma surface treatment to improve the degree of bonding of the polyamide layer.

As the hydrophilic tendency of the polymer support layer is increased, the initial wettability of the polyfunctional amine aqueous solution is improved and the penetration amount of the amine aqueous solution is increased, thereby increasing the degree of bonding between the support layer and the polyamide layer.

The plasma surface treatment may be a gas or a liquid including sulfur oxides and nitrogen oxides capable of binding a hydrophilic radical such as an amine radical, a hydroxyl radical or a sulfonated radical to the surface of the polymer support layer. More preferably, a gas or liquid such as ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), oxygen (O ₂ ), nitrogen (N ₂ ), sulfuric acid (H ₂ SO ₄ ) or water (H ₂ O) may be used. And most preferably, hydrogen sulfide (H ₂ S) gas capable of binding sulfonated radicals which most effectively acts to improve the penetration of the aqueous amine solution.

The gases may be injected at a flow rate of 0.2 to 30 L / min, and inert gases such as hydrogen (H ₂ ) gas or helium (He) and argon (Ar) may be injected together as a carrier gas.

Such a plasma surface treatment is preferably carried out at a temperature of 0 to 80 DEG C at a rate of 1 to 200 mm / s and a discharge treatment of 100 to 1000 W, and may be plasma-treated for 10 to 600 seconds.

As described above, the surface of the plasma-treated support layer may have a contact angle of 45 ° or less and an initial wettability of 70% or more.

 In the step (3), the polymer support layer is immersed in an aqueous solution containing a polyfunctional amine and then contacted with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer.

The polyamide layer of the present invention ensures stain resistance and chemical resistance due to inherent physical properties of the material. In addition, although the single-layer structure has a large pore size, it is difficult to remove a small salt such as monovalent ions, but the membrane of the composite membrane structure of the present invention having a polyamide layer can remove monovalent ions. That is, it is possible to achieve a high salt rejection rate and to prevent the dissolution of the solute in the induction solution in the reverse osmosis direction.

Specifically, a polymeric support layer is immersed in an aqueous solution containing a polyfunctional amine such as metaphenyldiamine, paraphenyldiamine, orthophenyldiamine, piperazine or alkylated piperidine, and then a polyfunctional acyl halide, a polyfunctional sulfonyl A polyamide layer can be formed by interfacial polymerization between the compounds by contacting an organic solution containing a polyfunctional acid halide compound such as a halide or a polyfunctional isocyanate.

Further, a hydrophilic compound may be further added to an aqueous solution containing the polyfunctional amine, and then an organic solution containing a polyfunctional acid halide compound may be contacted on the surface of the polymer layer to form a polyamide Layer can be formed. At this time, the compound containing the hydrophilic group may be present in an amount of 0.001 to 8% by weight, more preferably 0.01 to 4% by weight in the aqueous solution.

The hydrophilic compound added to the aqueous solution containing the polyfunctional amine is a hydrophilic compound having at least any one hydrophilic functional group selected from the group consisting of hydroxyl group, sulfonate group, carbonyl group, trialkoxysilane group, anion group and tertiary amino group And more preferably a hydrophilic amino compound.

More specifically, preferred examples of the hydrophilic compound having a hydroxyl group include 1,3-diamino-2-propanol, ethanolamine, diethanolamine, 3-amino-1-propanol, 4-amino-1-butanol, 2 It may be any one or more selected from the group consisting of -amino-1-butanol.

Hydrophilic compounds having a carbonyl group are selected from the group consisting of aminoacetaldehyde dimethyl acetal, α-aminobutyrolactone, 3-aminobenzamide, 4-aminobenzamide and N- (3-aminopropyl) -2-pyrrolidinone It may be any one or more.

Further, the hydrophilic compound containing a trialkoxysilane group may be any one or more selected from the group consisting of (3-aminopropyl) triethoxysilane and (3-aminopropyl) trimethoxysilane.

Examples of the hydrophilic compound having an anion group include glycine, taurine, 3-amino-1-propenesulphonic acid, 4-amino-1-butenesulphonic acid, 2-aminoethyl hydrogen sulfate, 3-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulphonic acid, 4-aminobenzenesulphonic acid, 3-aminopropylphosphonic acid, 3-amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid It may be any one or more selected from the group consisting of Ix acid, 6-aminohexenoxy acid, 3-aminobutanic acid, 4-amino-2-hydroxybutyric acid, 4-aminobutyric acid and glutamic acid have.

Examples of the hydrophilic compound having one or more tertiary amino groups include 3- (diethylamino) propylamine, 4- (2-aminoethyl) morpholine, 1- - diamino-N-methyldipropylamine and 1- (3-aminopropyl) imidazole.

The present invention also relates to a polymeric support layer; And a polyamide layer formed on one surface of the polymer support layer, wherein the surface of the polymer support layer facing the polyamide layer is subjected to plasma treatment to be hydrophilic surface-modified.

The surface of the polymer support layer facing the polyamide layer of the present invention can satisfy a contact angle of 45 DEG or less and an initial wettability of 70% or more.

 FIG. 1 is a cross-sectional view of a quasi-osmosis membrane according to a preferred embodiment of the present invention. Referring to FIG. 1, a quasi-osmosis membrane 200 according to an embodiment of the present invention includes a nonwoven fabric layer 210, And a polyamide layer 230 formed on the polymer support layer.

 The nonwoven fabric layer 210 is not particularly limited as long as the nonwoven fabric layer 210 serves as a support for the membrane, but is more preferably synthetic fiber selected from the group consisting of polyester, polypropylene, nylon, and polyethylene; Or natural fibers including cellulosic fibers; And the nonwoven fabric layer can control the physical properties of the membrane according to porosity and hydrophilicity of the material.

The porosity of the nonwoven fabric layer 210 may be used as long as it satisfies the air permeation amount of 2 cc / cm 2 sec or more, and more preferably, if the material satisfies the air permeation amount of 2 to 20 cc / cm 2 sec. Can be. At this time, when the average pore size of the nonwoven fabric layer 210 of the present invention is preferably 1 to 600 탆, and more preferably 5 to 300 탆, smooth permeation of water and water permeability required for the positive osmosis membrane can be enhanced . The thickness of the nonwoven fabric layer 210 of the present invention is preferably 20 to 150 占 퐉. If the thickness is less than 20 占 퐉, the strength and support of the entire membrane are insufficient.

 The polymer supporting layer 220 formed on the nonwoven fabric layer 210 is not particularly limited as long as it can form a positive osmosis membrane. However, in order to take mechanical strength into account, it is preferred to use a polymer having a weight average molecular weight in the range of 65,000 to 150,000 And preferred examples thereof include a polysulfone-based polymer, a polyamide-based polymer, a polyimide-based polymer, a polyester-based polymer, an olefin-based polymer, a polybenzimidazole polymer, polyvinylidene fluoride or polyacrylonitrile Or mixed form.

The support layer 220 may further include 0.5 to 15% by weight of a sulfonated polysulfone-based polymer. By further including the sulfonated polysulfone-based polymer, hydrophilicity can be maximized and the phase separation rate can be controlled. If the sulfonated polysulfone polymer is less than 0.5% by weight, the hydrophilicity improvement effect due to the sulfonated polysulfone polymer is insufficient. If the sulfonated polysulfone polymer is more than 15% by weight, the viscosity of the polymer solution becomes low, making it difficult to form a film. Can be.

In addition, the polymer support layer 220 has a porosity of 30 to 80%, and may include finger-like macropores having a long axis of 1 to 300 um and a short axis of 0.1 to 6 um. The thickness of the polymer support layer 220 is preferably minimized for increasing the flow rate, and the present invention can satisfy the range of 30 to 300 mu m.

 The surface of the polymer supporting layer 220 facing the polyamide layer 230 may have a contact angle of 45 ° or less and an initial wettability of 70% or more.

 This is because as the support layer surface 220 is plasma treated, the surface is modified to be hydrophilic, thereby increasing the hydrophilization tendency, thereby reducing the contact angle and improving the initial wettability of the polyfunctional aqueous amine solution. Therefore, the penetration amount of the amine aqueous solution may be increased and the bonding degree between the support layer 220 and the polyamide layer 230 may be increased.

The hydrophilic surface modification of the support layer 220 uses a gas or liquid containing nitrogen oxides and sulfur oxides capable of binding hydrophilic radicals such as amine radicals, hydroxyl group radicals or sulfonated radicals to the surface of the support layer 220. Plasma treatment may be performed, more preferably ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), oxygen (O ₂ ), nitrogen (N ₂ ), sulfuric acid (H ₂ SO ₄ ), water (H ₂ O), or the like. Gas or liquid can be used. Most preferably, hydrogen sulfide (H ₂ S) gas capable of binding sulfonated radicals which most effectively acts to improve the penetration of the aqueous amine solution can be used.

 The polyamide layer 230 formed on the polymer support layer 220 may be formed by interfacial polymerization after being immersed in an aqueous solution containing a polyfunctional amine and then brought into contact with an organic solution containing a polyfunctional acid halide compound. The polyamide layer 230 can secure a high salt removal rate by the relatively dense pores ensuring the stain resistance and the chemical resistance from the inherent properties of the material.

The polyamide layer 230 may have a thickness of 0.01 to 1 μm. When the thickness of the polyamide layer 230 is less than 0.01 μm, the salt removal ability may be deteriorated so that the polyamide layer 230 may not serve as a selection layer. There may be a problem of deterioration.

≪ Example 1 >

Polymer solution containing 22 parts by weight of polysulfone (PSf) per 100 parts by weight of solvent methyl-2-pyrrolidone (NMP) was prepared. This was applied to a thickness of 100um on a nonwoven fabric having a thickness of 40um, and then phase-transformed in water at room temperature to form a polymer support layer. Then, the formed polymer support layer was stored in ultrapure water for one day to extract the solvent.

Helium as a carrier gas and hydrogen sulfide as a source gas were injected at a flow rate of 20 L / min on the film surface from which the solvent was extracted, and discharge treatment was performed by low temperature induction plasma treatment in a plasma apparatus. The discharge treatment rate was 30 mm / min, and was carried out at 200 W for 50 seconds to introduce sulfonated radicals to the surface of the support layer.

The polymer surface-treated polymer support layer was immersed in an aqueous solution containing 2% by weight of meta-phenylenediamine (MPD) and an organic solution containing 0.1% by weight of trimethoyl chloride (TMC) in an ISOPAR solvent (Exxon Corp.) To form a polyamide layer by polymerization reaction between the above compounds to prepare a composite membrane.

≪ Example 2 >

And 1.2 parts by weight of a sulfonated polysulfone-based polymer was further contained in the polymer solution.

≪ Example 3 >

Except that the polymer solution further contained 1.2 parts by weight of a sulfonated polysulfone-based polymer, and that a hydrosilyl radical was introduced using oxygen instead of hydrogen sulfide as a source gas.

<Example 4>

Except that 1.2 parts by weight of a sulfonated polysulfone-based polymer was further added to the polymer solution and discharged at 30 W for 10 seconds.

<Comparative Example>

The procedure of Example 1 was repeated except that the polymer support layer was not subjected to the plasma surface treatment.

<Experimental Example>

1. Measurement of membrane flow

The flow of water in the direction of the inducing solution from the raw water was induced between the membranes prepared above, and the amount of water per hour was measured by measuring the weight of the inducing solution with respect to time. At this time, 2 M NaCl was used as the induction solution, and ultrapure water (osmotic pressure of about 100 atm) was used as raw water.

2. Measurement of reverse diffusion of membrane

(2M NaCl) was used as the induction solution and the electric conductivity change of the salts introduced into the raw water side (ultrapure water) in the induction solution was measured by using ultrapure water (osmotic pressure of about 100 atm) as the raw water, The conductivity of the solution between electrodes having a distance of 1 cm from a certain membrane area was measured using a conductivity meter to evaluate the degree of despreading in units of the change in conductivity per minute (μS / cm) [solid dissolved in water Was expressed as μS / cm × 0.5 to 0.6 = TDS (Total Dissolved Solids, mg / L).

The results obtained by converting the conductivity values of the membrane area (17 cm 2) to the conductance values per minute (μS / cm) / min obtained above are shown in Table 1 below.

3. Measurement of contact angle of support layer

The polymer support layer sample is immobilized on the measurement plate, the water drop is dropped thereon, and the time from when the water drop falls on the polymer support layer to when it is absorbed is captured with a camera having a frame rate of 250 fps per second. The numerical value indicates the angle of the water droplet on the polymer support layer. The higher the numerical value, the more hydrophobic nature, and the lower hydrophilic nature.

4. Initial wettability measurement

The water permeability of the dried osmosis membrane and the osmosis membrane were completely immersed in an aqueous 30% alcohol solution and then allowed to stand for 5 minutes. After washing the pure osmosis membrane with pure water, the water permeability of the osmosis membrane with the alcohol removed was measured, The initial wettability is obtained by substituting the water permeability values into the following equations.

Initial wettability (%) = (water permeability of dry osmosis membrane) / (water permeability of alcohol and pure osmosis membrane treated) x 100

5. Measurement of polyamide layer bonding degree

 After the membrane was immersed in 2000 ppm NaOCl for 7 days, the flow rate and the degree of back diffusion of the salt were measured.

 This is an experiment to determine the degree of bonding of the polyamide layer and the polymer support layer, and indirectly grasps the degree of bonding of the polyamide layer by observing the change in physical properties of the polyamide, which is weak to chlorine.

When the polyamide separator was immersed in 2000 ppm NaOCl for 7 days, OCl-ion attacked the NH bond in the polyamide bond to decompose the amide structure. This decomposition affects the selectivity of the membrane, which results in an increase in the flow rate and an increase in the degree of despreading of the salt.

flux
(gfd) Despreading of salt
(μS / cm) / min) Support layer contact angle
(°) Early wetting
(%) Example 1 4.32 0.025 45 70 Example 2 15.65 0.489 42.5 82 Example 3 12.72 0.501 44.6 79 Example 4 9.12 0.0544 44.2 65 Comparative Example 1.12 0.021 93 10

2000 ppm NaOCl after 7 days contact
Flow rate (GFD) 2000 ppm NaOCl after 7 days contact
Salt back diffusion (μS / cm) / min) Example 1 5.12 0.12 Example 2 16.98 0.523 Example 3 14.20 0.724 Example 4 9.86 0.072 Comparative Example Not measurable Not measurable

As can be seen from Tables 1 and 2, the contact angles of the surfaces of the support layers of Examples 1 to 4 were remarkably reduced, and the initial wettability was significantly increased, and hydrophilicity was improved, as compared with Comparative Examples in which the surface of the polymer support layer was not subjected to plasma treatment. Due to this, the polyamide layer is firmly formed, and the bonding degree with the support layer is increased, so that the damage of the polyamide layer is small because the increase in flow rate and the increase in salt diffusion during the 2000 ppm NaOCl contact is small.

Claims (13)

(1) forming a polymer support layer by doping a polymer solution on a nonwoven fabric layer;
(2) a step of plasma-treating the surface of the polymer support layer to introduce a hydrophilic radical; And
(3) immersing the polymer support layer in an aqueous solution containing a polyfunctional amine, and then contacting the polymer support layer with an organic solution containing a polyfunctional acid halide compound to form a polyamide layer; and Way.
The method of claim 1,
Wherein the polymer is selected from the group consisting of a polysulfone polymer, a polyamide polymer, a polyimide polymer, a polyester polymer, an olefin polymer, a polybenzimidazole polymer, polyvinylidene fluoride and polyacrylonitrile Wherein the at least one osmosis membrane comprises at least one water-soluble polymer.
The method of claim 1,
The polymer solution of step (1) is a method for producing a hollow fiber type forward osmosis membrane, characterized in that it comprises 0.1 to 7 parts by weight of sulfonated polysulfone polymer based on 100 parts by weight of a solvent.
The method of claim 1,
The plasma surface treatment of step (2) is carried out with ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), oxygen (O ₂ ), nitrogen (N ₂ ), sulfuric acid (H ₂ SO ₄ ) and water (H ₂ O). Method for producing a forward osmosis membrane, characterized in that using any one or more gas or liquid selected from the group consisting of.
The method of claim 1,
Wherein the plasma surface treatment in the step (2) is carried out at a discharge power of 100 to 1000 W for 10 to 600 seconds.
Polymer backing layer; And
And a polyamide layer formed on one surface of the polymer support layer,
The surface of the polymer support layer facing the polyamide layer is a forward osmosis membrane, characterized in that the hydrophilic surface modified by plasma treatment.
Polymer backing layer; And
And a polyamide layer formed on one surface of the polymer support layer,
The polymer support layer has a contact angle of 45 ° or less, and the forward osmosis membrane, characterized in that the initial wettability is 70% or more.
The method according to any one of claims 6 to 7,
Wherein the polymeric support layer is formed on the nonwoven fabric layer.
The method according to claim 6,
Wherein the polymer support layer is selected from the group consisting of polysulfone-based polymers, polyamide-based polymers, polyimide-based polymers, polyester-based polymers, olefin-based polymers, polybenzimidazole polymers, polyvinylidene fluoride and polyacrylonitrile Wherein the one or more osmosis membranes comprise at least one or more of the following.
The method according to claim 6,
The polymer support layer is a forward osmosis membrane, characterized in that containing 0.5 to 15% by weight of sulfonated polysulfone polymer.
The method according to claim 6,
The polymer support layer has a porosity of 30 to 80%, forward osmosis membrane, characterized in that it comprises a finger-like macropores of 1 to 300um long axis and 0.1-6um short axis.
The method according to claim 6,
The plasma surface-treated support layer has a contact angle of 45 ° or less and an initial wetting property of 70% or more.
The method according to claim 6,
The thickness of the polymer support layer is 30 to 300um, the thickness of the polyamide layer is forward osmosis membrane, characterized in that 0.01 to 1um.

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