KR101391653B1 - Hollow fiber type forward osmosis membrane and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a hollow osmosis membrane having a polyamide layer coated on the surface of a hollow support, and a process for producing the same.
The hollow fiber type positive osmosis membrane of the present invention is a structure in which a polyamide layer is coated on the surface of a hollow support having a pore structure of a finger type having a porosity of 30 to 80%. The hollow fiber pore structure smoothly Water is introduced into the porous support to realize a high water permeability in the osmotic direction and the polyamide layer is coated on the surface of the hollow support so that the stain resistance and chemical resistance are secured and the solute of the induction solution in the reverse osmosis direction is despread Is minimized and can be usefully used for seawater separation at a high concentration.

Description

[0001] HOLLOW FIBER TYPE FORWARD OSMOSIS MEMBRANE AND MANUFACTURING METHOD THEREOF [0002]

More particularly, the present invention relates to a structure in which a polyamide layer is coated on a surface of a hollow support having a porosity of 30 to 80% Water can be smoothly introduced into the induction solution in the raw water portion to realize a high water permeability in the osmotic direction and the polyamide layer can be coated on the surface of the hollow support so as to ensure stain resistance and chemical resistance, Which is suitable for seawater separation at a high concentration by minimizing the despreading property of a solute of a hollow fiber type and a method for producing 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 plays an important role in maintaining the high osmotic pressure while maintaining the constant concentration of the inducing solute, while allowing water to flow into the inducing solution from the raw water through the membrane well. For this purpose, it is most important that the osmosis membrane has 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, the solute should not diffuse into the low concentration solution in the high concentration solution.

Conventionally, U.S. Patent Application Publication No. 2006-0226067 discloses a method for producing a purified osmosis membrane. A cellulose acetate triacetate, which is a hydrophilic material, is used to produce a purified osmosis membrane. More specifically, on a support layer having a thickness of 25 to 75 μm, (FO) mode by using an induction solution in the film, the flow rate of which was 11 gfd level. When the flow rate was 11 gfd A high flow rate osmosis membrane is proposed. 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.

Also, according to International Patent Publication No. 2008-137082, a polysulfone solution is cast on a nonwoven fabric to prepare a membrane having an ultrafiltration membrane level, and a polyfunctional amine and a polyfunctional acyl halide are interfacially polymerized on the membrane surface, Amide reverse osmosis membrane was prepared, and a membrane from which only the nonwoven fabric was removed was applied to a 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 the flow rate is low, so that the use of the membrane is practically limited.

As a result, the present inventors have made a new structure of a hollow-core type osmosis membrane as a result of trying to obtain a membrane suitable for a normal osmosis process, which is realized by osmotic pressure due to a difference in concentration between two solutions, Accordingly, it is possible to optimize the structure thickness and the pore structure required in the field of the forward osmosis membrane to smoothly flow water into the induction solution from the raw water section, realize high water permeability and flow rate in the osmotic direction, ensure stain resistance and chemical resistance, Confirming the despreading property of the salt, thereby completing the present invention.

It is an object of the present invention to provide a hollow positive osmosis membrane.

It is another object of the present invention to provide a method of manufacturing a hollow fiber type positive osmosis membrane.

The present invention provides a positive osmosis membrane coated with a polyamide layer on a hollow support surface having a porosity of 30 to 80%.

In the hollow fiber positive osmosis membrane of the present invention, the hollow fiber is formed from a dope solution containing 0.5 to 5% by weight of a sulfonated polysulfone-based polymer in a polymer, and the preferred polymer is a poly Sulfone type polymers; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And polyacrylonitrile, or a mixed form thereof.

In the hollow fiber positive osmosis membrane of the present invention, the hollow fiber has an outer diameter / inner diameter ratio of 1.1 to 0.3, and a hollow fiber has a cross-sectional thickness of 30 to 250 탆.

According to the above feature, the hollow fiber type positive osmosis membrane of the present invention has a conductivity value of 9.0 μS / cm or less per minute at a constant membrane area (17 cm ² ) and a conductivity value of 0.54 (μS / cm) / min · cm ² or less per unit area , And satisfies a flow rate of 3 to 20 gfd in an induction solution of raw water and 2M NaCl or an osmotic pressure condition equivalent to the above.

The present invention relates to a method for producing a hollow fiber membrane, comprising the steps of: 1) simultaneously sputtering a dope solution containing 0.5 to 5% by weight of a sulfonated polysulfone-based polymer in a polymer and a hollow core solution, Impregnated into a coagulation bath and dried to form a hollow fiber having a porosity of 30 to 80%

2) The hollow fiber is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine and then the excess aqueous solution is removed. There is provided a method for producing a positive osmosis membrane, which comprises contacting an organic solution containing a polyfunctional acid halide compound to form a polyamide layer by interfacial polymerization between the compounds.

In the method for producing a positive osmosis membrane of the present invention, the dope solution may be prepared by dissolving a polysulfone-based polymer containing polysulfone and polyethersulfone in a dope solution; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And 10 to 25% by weight of a polymer selected from the group consisting of polyacrylonitrile and a mixture thereof is contained in the organic solvent.

Further, it is preferable that the core solution comprises a mixture ratio of an organic polar solvent (solvent A): water (solvent B) of 4: 6 to 9: 1, and the organic polar solvent is dimethylacetamide, N-methyl- Or dimethylformamide.

In the method for preparing a purified osmosis membrane of the present invention, the air gap is 1 to 15 cm, and the temperature of the coagulation bath is maintained at 30 to 70 ° C to control the pore structure of the hollow fiber membrane. Accordingly, the method for producing a quasi-osmosis membrane of the present invention can produce hollow osmosis membranes having an outer diameter / inner diameter ratio of 1.1 to 0.3 and a hollow fiber cross-sectional thickness of 30 to 250 μm.

In the production process of the present invention, the polyamide layer is further subjected to a post-treatment step in which it is immersed in a solution containing 3 to 40% glycerol and dried after the forming step.

The present invention can provide a hollow positive osmosis membrane having a structure in which a polyamide layer is coated on the surface of a hollow support.

Accordingly, according to the structure of the hollow fiber having the porosity of 30 to 80%, the hollow fiber type fixed osmosis membrane of the present invention smoothly flows water into the induction solution in the raw water portion, realizes high water permeability in the osmotic direction, The polyamide layer formed on the surface ensures the stain resistance and chemical resistance and also satisfies the property of preventing the back diffusion of the inducing solution solute in the reverse osmosis direction. In addition, the present invention can provide a method of manufacturing a positive osmosis membrane in which the thickness and porosity of the structure of a quasi-osmosis membrane are optimized in order to obtain a physical property and structure suitable for a quasi-osmosis membrane.

1 is a cross-sectional photograph of a hollow fiber type osmosis membrane according to Example 1 of the present invention, which is enlarged by 70 times.
FIG. 2 is a photograph showing a 500-fold magnification of the cross section of the hollow fiber type osmosis membrane of FIG. 1,
FIG. 3 is a cross-sectional photograph of the hollow fiber type osmosis membrane according to the second embodiment of the present invention, which is magnified 70 times.
FIG. 4 is a photograph showing a 500-fold magnification of the cross section of the hollow fiber-type osmosis membrane of FIG. 3,
FIG. 5 is a cross-sectional photograph of the hollow fiber type osmosis membrane according to the third embodiment of the present invention, which is magnified 70 times.
FIG. 6 is a photograph of the cross section of the hollow fiber-type osmosis membrane of FIG. 5 enlarged 500 times,
FIG. 7 is a cross-sectional photograph of a hollow-type positive osmosis membrane according to Comparative Example 1 of the present invention, magnified 100 times . FIG .
FIG. 8 is a photograph showing a 500-fold magnification of the cross section of the hollow fiber type osmosis membrane of FIG.

In order to achieve the above object, the present invention provides a hollow positive osmosis membrane having a polyamide layer coated on the surface of a hollow support having a porosity of 30 to 80%.

1) a hollow support

In the hollow fiber positive osmosis membrane of the present invention, it is preferable that the hollow fiber has an outer diameter / inner diameter ratio of 1.1 to 0.3 and a hollow fiber cross-sectional thickness of 30 to 250 μm.

In this case, more preferably, the hollow fiber has an outer diameter / inner diameter ratio of 1.1 to 2.0, and most preferably 1.1 to 1.5. When the ratio is less than 1.1, the strength of the film is excessively thin and the strength is low. I do not.

In addition, the hollow fiber cross-sectional thickness is designed for the purpose of increasing the flow rate of the quasi-osmosis membrane. Outside of the above range, the strength is too weak, and the effect of improving the flow rate will be insignificant.

FIGS. 1 to 6 are enlargement of cross sections of the hollow fiber type positive osmosis membrane produced in the embodiment of the present invention. In each of the hollow fiber type positive osmosis membranes produced in Examples 1 to 3, 92 μm, 107 μm and 129 Mu m.

1 to 6, the pore structure of the hollow fiber is observed as a finger-like pore shape, the porosity is 30 to 80%, and the pore structure of the pore is low.

On the other hand, FIG. 7 and FIG. 8 are photographs of a cross-section of a hollow-type positive osmosis membrane of Comparative Example 1 produced without addition of a sulfonated polysulfone-based polymer by a magnification of 100 times and 500 times, have.

The design of the pore structure of such a membrane is also influenced by the coating solution forming the hollow fiber. The dope solution used in the hollow fiber type positive osmosis membrane of the present invention is a solution in which 0.5 to 5% by weight of a sulfonated polysulfone polymer is contained in the polymer will be.

At this time, by containing a sulfonated polysulfone-based polymer in the polymer, the hydrophilicity of the formed film is imparted and the phase separation rate is controlled.

Accordingly, the sulfonated polysulfone-based polymer preferably contains 0.5 to 5 wt% of the total dope solution. When the content of the sulfonated polysulfone polymer is less than 0.5 wt%, the effect of improving the hydrophilicity of the expected membrane is insufficient, %, The viscosity of the polymer solution is lowered, and film formation is difficult, which is not preferable.

Examples of the polymer forming the hollow fiber type positive osmosis membrane of the present invention include a polysulfone-based polymer including polysulfone and polyethersulfone; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And polyacrylonitrile, or a mixed form thereof.

In the embodiments of the present invention, a dope solution containing a sulfonated polysulfone-based polymer in a polysulfone is described, but the present invention is not limited thereto.

According to the structural characteristics of the hollow fiber described above, water is smoothly introduced into the induction solution in the raw water portion and designed to have a high water permeability in the osmotic direction.

2) Polyamide layer

The polyamide layer coated on the surface of the above hollow support will be described in detail.

In the hollow fiber type positive osmosis membrane of the present invention, the polyamide layer is formed by contacting an organic solution containing a polyfunctional acid halide compound with an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, .

When the low-concentration raw water flows into the hollow fiber by the difference in concentration between the two solutions, the hollow fiber type positive osmosis membrane of the present invention is permeated through the polyamide layer which is the outermost side of the positive osmosis membrane into the hollow fiber support which is the inner layer of the positive osmosis membrane The separation process is carried out by flowing into the induction solution. At this time, if the raw water filtered by the polyamide layer having an excellent salt rejection rate penetrates into the hollow support having the pore structure of the finger type having a porosity of 30 to 80%, water flows smoothly into the induction solution, The high water permeability and the flow rate of the water are achieved.

In addition, the osmotic pressure due to the difference in concentration between the two solutions is used as a driving force, and the osmosis membrane undergoes reverse diffusion of the salt in the reverse osmosis direction. In the reverse osmosis membrane structure of the present invention, The solute of the derivatizing solution can be prevented from being despread.

Therefore, the hollow fiber type osmosis membrane manufactured in the embodiment of the present invention has a conductivity value of 9.0 μS / cm or less per minute at a constant membrane area (17 cm ² ) and a conductivity of 0.54 (μS / cm) / min · cm ² As a result of the conductivity value, it can be confirmed that the salt is prevented from reverse diffusion in the reverse osmosis direction.

From the above, according to the structure of the polyamide layer, it is possible not only to secure a high salt rejection rate, chemical resistance and pH stability, but also to prevent reverse solubility of the solute in the induction solution in the reverse osmosis direction.

In addition, the hollow fiber positive osmosis membrane of the present invention satisfies a flow rate of 3 to 20 gfd in an induction solution of raw water and 2M NaCl or an equivalent level of osmotic pressure.

Hereinafter, a method for producing the hollow fiber type positive osmosis membrane of the present invention will be described in detail.

Specifically, the present invention relates to a method for producing a hollow fiber membrane, comprising the steps of: 1) simultaneously sputtering a dope solution containing 0.5 to 5% by weight of a sulfonated polysulfone-based polymer in a polymer and a core solution for hollow formation, impregnating the membrane with a coagulation bath after exposure to air, ≪ / RTI > to < RTI ID = 0.0 > 80%

2) The hollow fiber is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine and then the excess aqueous solution is removed. There is provided a method for producing a positive osmosis membrane, which comprises contacting an organic solution containing a polyfunctional acid halide compound to form a polyamide layer by interfacial polymerization between the compounds.

1) Hollow fiber formation step

Step 1 is designed to optimize the pore structure to be suitable for the positive osmosis membrane.

First, the dope solution incorporates a sulfonated polysulfone polymer in the polymer, thereby realizing a hydrophilic improvement. In this case, the sulfonated polysulfone polymer preferably contains 0.5 to 5% by weight of the total dope solution. If the content of the sulfonated polysulfone polymer is less than 0.5% by weight, the effect of improving the hydrophilicity of the expected membrane is insufficient, The viscosity of the polymer solution is lowered, and film formation is difficult, which is not preferable.

The polymer has a weight average molecular weight in the range of 65,000 to 150,000 in consideration of mechanical strength, and preferred examples thereof include a polysulfone-based polymer including polysulfone and polyethersulfone; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And polyacrylonitrile, or a mixture thereof may be used. At this time, the polymer contains 10 to 25% by weight based on the total dope solution.

In addition, the dope solution for forming the hollow fiber of the present invention may further contain a porosity regulator made of a hydrophilic material having an affinity with moisture in the humidified air. Preferred pore regulators include glycols such as ethylene glycol and glycerol; Alcohols such as ethanol and methanol; Ketones such as acetone; Polyvinyl pyrrolidone, polyethylene glycol, and the like, or a mixture of two or more of them may be used.

At this time, the preferable content of the pore-controlling agent is 0.1 to 5% by weight based on the total dope solution.

The solvent used in the dope solution for forming the hollow fiber of the present invention is N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO) and dimethylacetamide And one or more selected from the group consisting of

At this time. The core solution is a mixed solvent consisting of an organic polar solvent (solvent A): water (solvent B), and preferred examples of the organic polar solvent include dimethylacetamide, N-methyl-2-pyrrolidone or dimethylformamide Can be used.

The condition of the mixed solvent constituting the core solution is such that when the organic polar solvent (solvent A): water (solvent B) is formed at a mixing ratio of 4: 6 to 9: 1, the pore structure of the hollow fiber is observed in the form of a finger, Respectively. At this time, if the ratio of the organic polar solvent is less than 4, pores of a structure of a bead structure are formed to a large extent or pores of an undesirable structure are formed on the surface of an inner membrane, If it exceeds 9, phase transition of the dope solution is not smoothly performed.

The hollow fiber of the present invention can adjust the thickness and outer / inner diameter ratio of the cross section of the hollow fiber according to the feed rate (rpm) of the dope solution and the inflow amount (cc / min) of the core solution, 6/6 to 6/42, and more preferably 6/30 to 6/42.

The hollow shaped article emitted from the double nozzle is exposed to air before it is immersed in the coagulation bath, and the pore structure of the hollow fiber can be optimized according to the length of the air gap.

Therefore, the air gap is preferably 1 to 15 cm, more preferably 3 to 7 cm. As the length of the air gap is longer, the thickness of the hollow fiber to be formed can be made thinner, and the pore structure of the skin layer and the core layer of the hollow fiber can be made asymmetric as the air exposure time becomes longer. At this time, if the air gap length is less than 1 cm, the pores are dense only in the hollow skin layer, which is not suitable for the use of the osmosis membrane, If it is more than 15 cm, the film may be broken due to the decrease in strength, which is not preferable.

Further, when the temperature of the coagulation bath is as low as 0 to 20 占 폚 when the coagulation bath is impregnated after passing through the air gap, the surface of the hollow fiber will become dense. Thus, in the present invention, the temperature of the coagulation bath is maintained at a higher temperature than room temperature, preferably 30 to 70 캜, and more preferably 40 to 60 캜 to prepare a hollow fiber membrane.

When the coagulation bath temperature is 30 to 70 캜, the pore structure of the hollow fiber can be optimized by promoting the phase transition rate.

Due to the above process characteristics, it is possible to form a hollow fiber having a pore-type pore structure having a porosity of 30 to 80% from the production method of the present invention. More specifically, the hollow fiber has an outer diameter / inner diameter ratio of 1.1 to 0.3 , And the hollow fiber has a cross-sectional thickness of 30 to 250 mu m.

2) Polyamide layer formation step

The hollow fiber formed in the step 1) is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, followed by washing the excess aqueous solution. The polyamide layer is formed by interfacial polymerization between the compounds by contacting an organic solution containing a polyfunctional acid halide compound.

Specifically, an aqueous solution containing a polyfunctional amine selected from metaphenyldiamine, paraphenyldiamine, orthophenyldiamine, piperazine, or alkylated piperidine and an alkylated aliphatic amine on the surface of the hollow support, Contacting an organic solution containing a polyfunctional acid halide compound selected from an acyl halide, a polyfunctional sulfonyl halide or a polyfunctional isocyanate to form a polyamide layer by interfacial polymerization between the compounds.

Further, after a hydrophilic compound is further contained in an aqueous solution containing the polyfunctional amine-containing or alkylated aliphatic amine, the resultant is contacted on the surface of the hydrophilic polymer layer with an organic solution containing a polyfunctional acid halide compound, It is possible to form a polyamide layer having improved stain resistance. At this time, the compound containing the hydrophilic group is present in the aqueous solution in an amount of 0.001 to 8 wt%, more preferably 0.01 to 4 wt%.

The hydrophilic compound added to the aqueous solution containing the polyfunctional amine-containing or alkylated aliphatic amine is at least one selected from the group consisting of hydroxyl group, sulfonated group, carbonyl group, trialkoxysilane group, anion group and tertiary amino group Is a hydrophilic compound having a hydrophilic functional group. More preferably a hydrophilic amino compound.

More specifically, Preferred examples of the hydrophilic compound having a hydroxy group include 1,3-diamino-2-propanol, ethanolamine, diethanolamine, 3-amino-1-propanol, -Butanol. ≪ / RTI >

The hydrophilic compound having a carbonyl group is selected from the group consisting of aminoacetaldehyde dimethylacetal,? -Aminobutylolactone, 3-aminobenzamide, 4-aminobenzamide and N- (3-aminopropyl) -2-pyrrolidinone do.

Further, the hydrophilic compound containing a trialkoxysilane group is selected from the group consisting of (3-aminopropyl) triethoxysilane and (3-aminopropyl) trimethoxysilane.

Examples of the hydrophilic compound having an anionic group include glycine, taurine, 3-amino-1-propenesulfonic acid, 4-amino-1-butenesulfonic acid, 2-aminoethylhydrogensulfate, 3-aminobenzenesulfonic acid, Amino-3-hydroxybenzoic acid, 3-amino-4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid, 3-aminopropylphosphonic acid, Aminobutane oxidase, 4-amino-2-hydroxybutyric acid, 4-aminobutric acid and glutamic acid.

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 polyamide layer of the present invention ensures the stain resistance and chemical resistance from the inherent properties of the material, and the polyamide layer is formed on the skin layer of the hollow fiber membrane, thereby securing a high salt removal rate by the relatively dense pores.

Particularly, according to the polyamide layer formed on the surface of the hollow support of the present invention, the ortho-osmotic membrane of the present invention has a conductivity value of 9.0 μS / cm or less per minute at a constant membrane area, particularly 0.54 (μS / cm) / min. cm < ² > so that the dissolution of the solute in the inducing solution in the reverse osmosis direction is minimized.

3) Post-treatment process

After the step 2), the formed hollow osmosis membrane is immersed in a 3 to 40% glycerol-containing solution and immediately dried to complete the membrane preparation step.

By performing the surface treatment with the glycerol-containing solution, drying of the surface of the formed film is prevented, and the pore structure formed is not collapsed, so that service life of the film can be improved.

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

The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

≪ Example 1 >

Polysulfone And a coating solution containing 18% by weight of a sulfonated polysulfone-based polymer and 1% by weight of a sulfonated polysulfone-based polymer in a solvent of methylpyrrolidone (NMP) were prepared to remove air bubbles. The dope solution was introduced into one direction of the double nozzle, and the hollow core solution was introduced into the distal end of the double nozzle to be radiated into a hollow shape. At this time, a solution having a mixing ratio of dimethylformamide to water of 9: 1 was used as the hollow core solution, and the feed rate (rpm) of the dope solution and the inflow amount (cc / min) of the core solution were adjusted to 6:42 .

Thereafter, it was exposed to air at an air gap of 3 cm, solidified by immersing it in a coagulation tank maintained at 40 占 폚, solidified for a predetermined time, and then the remaining solvent component contained in the hollow fiber was extracted in a water bath, And dried under atmospheric conditions to produce a hollow fiber.

The prepared hollow fiber was immersed in an aqueous solution containing 2% by weight of meta-phenylenediamine (MPD) for 1 minute, and then the surface water layer was removed by a pressing method. Thereafter, the mixture was immersed in an ISOPAR solvent (Exxon Corp.) in an organic solution containing 0.1% by weight of trimethoyl chloride (TMC) for 1 minute and subjected to interfacial polymerization, followed by natural drying at room temperature (25 ° C) for 1 minute and 30 seconds, . Thereafter, it was immersed in a 0.2 wt% sodium carbonate solution for 2 hours to remove unreacted residues and then washed with distilled water.

The prepared composite membrane was immersed in a 3% glycerol-containing solution and immediately dried.

≪ Example 2 >

The procedure of Example 1 was repeated except that the feed rate (rpm) of the dope solution and the inflow amount (cc / min) of the core solution were adjusted to 6:38.

≪ Example 3 >

The procedure of Example 1 was repeated except that the feed rate (rpm) of the dope solution and the inflow amount (cc / min) of the core solution were adjusted to 6:30.

<Example 4>

The procedure of Example 1 was repeated except that a coating solution containing 17% by weight of polysulfone and 2% by weight of a sulfonated polysulfone-based polymer in dimethylformamide solvent was used.

&Lt; Example 5 >

The procedure of Example 2 was repeated except that a coating solution containing 17% by weight of polysulfone and 2% by weight of a sulfonated polysulfone-based polymer in dimethylformamide solvent was used.

&Lt; Example 6 >

The procedure of Example 3 was repeated except that a coating solution containing 17% by weight of polysulfone and 2% by weight of a sulfonated polysulfone-based polymer in dimethylformamide solvent was used.

&Lt; Comparative Example 1 &

The procedure of Example 1 was repeated except that a coating solution containing 19% by weight of polysulfone was used without adding a sulfonated polysulfone-based polymer.

&Lt; Comparative Example 2 &

The properties were compared using a flat osmosis membrane made of a single material (Hydration Technology Innovation).

&Lt; Comparative Example 3 &

Physical properties were compared using a flat membrane reverse osmosis membrane on which a polyamide layer was formed on a polymer support layer composed of 18% by weight of polysulfone.

Experimental Example 1 Measurement of Membrane Flow Rate

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.

The methods of measuring the water permeability of the membranes prepared in Examples 1 to 6 and Comparative Examples 1 to 3 are as follows.

1) The membrane is cut and cut to a length of 100 mm and placed in a tube having a diameter of 10 mm and a length of 100 mm.

2) Port both sides of tube containing hollow fiber membrane with epoxy adhesive and harden.

3) Hollow core Membrane ends of the epoxy adhesive are solidified to allow water to flow through the inside of the membrane.

A module having a diameter of 10 mm and a length of 100 mm was prepared by the above method, and the permeation amount per unit area and minute was measured at a constant pressure (1 bar) through a sample holder. The results are shown in Table 1 below.

&Lt; Experimental Example 2 >

(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 conductivity values per minute (μS / cm) / min obtained above are shown in Table 1 below. The degree of despersion of the salt was evaluated from the result.

As shown in Table 1, in Comparative Example 1 in which the sulfonated polysulfone-based polymer was not contained in the dope solution of the present invention, the results showed that the properties such as flow rate, salt back diffusion and water permeability were deteriorated.

In addition, the osmosis membrane of Comparative Example 2, which is a flat membrane structure composed of a single material of cellulose triacetate as a hydrophilic material, exhibited a significantly higher flow rate in terms of flow rate. However, in terms of the reverse diffusion of the salt, It can not be utilized as an osmosis membrane.

When the membrane of Comparative Example 3, which is a reverse osmosis membrane of the conventional membrane structure, was applied to the forward osmosis membrane, the reverse diffusion of the salt due to the dense pore structure of the reverse osmosis membrane was extremely low. However, I do not.

Therefore, the membranes prepared in Examples 1 to 6 showed better flow rates than those of Comparative Example 3 in which the reverse osmosis membrane was evaluated by the positive osmosis module.

In particular, the membranes prepared in Examples 1 to 6 exhibited low salt despreading, having a flow rate of 4 to 6 gfd and a conductivity value of 0.45 μS / cm or less per minute (based on hollow fiber membrane area of 17 cm ² ). The inverse diffusion value of the salt converted to the area was observed to be less than 0.05 (μS / cm) /min.cm ² , so that the solute of the induction solution did not diffuse in the reverse osmosis direction and the requirement as the osmosis membrane was satisfied.

FIGS. 1 to 6 show cross sections of the hollow fiber type ortho-osmosis membrane prepared in Examples 1 to 3 of the present invention, in which the hollow fibers are observed with a finger-like pore structure and a porosity of 30 to 80% .

From the above results, the outer diameter / inner diameter ratio and the hollow fiber thickness of the hollow fiber type positive osmosis membrane produced in Examples 1 to 3 were observed to be 92 탆, 107 탆 and 129 탆, respectively.

As described above, the present invention provides a hollow structure type positive osmosis membrane having a novel structure coated with a polyamide layer on the surface of a hollow support.

According to the method of the present invention, a hollow fiber having a pore structure of a finger shape having a porosity of 30 to 80% is formed by designing a pore structure to obtain a physical property and structure suitable for a positive osmosis membrane, Water is smoothly introduced into the induction solution, thereby realizing high water permeability in the osmotic direction. Also, by coating the polyamide layer formed on the surface of the hollow support, it is possible to ensure stain resistance and chemical resistance, and to prevent reverse diffusion of the inducing solution solute in the reverse osmosis direction, can do.

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 (16)

A hollow-fiber positive osmosis membrane having a polyamide layer coated on a hollow support surface having a finger-like pore shape and porosity of 30 to 80%. The hollow-fiber positive osmosis membrane according to claim 1, wherein the hollow fiber is formed from a dope solution containing 0.5 to 5% by weight of a sulfonated polysulfone-based polymer in a polymer. The method of claim 2, wherein the polymer is selected from the group consisting of a polysulfone-based polymer including polysulfone and polyethersulfone; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And polyacrylonitrile, or a mixed form thereof. The hollow osmosis membrane according to claim 1, wherein the hollow fiber has an outer diameter / inner diameter ratio of 1.1 to 3.0. The hollow osmosis membrane according to claim 1, wherein the hollow fiber has a cross-sectional thickness of 30 to 250 탆. The hollow osmosis membrane according to claim 1, wherein the osmosis membrane has a conductivity value of 0.54 (μS / cm) / min · cm ² or less per unit area. The hollow osmosis membrane according to claim 1, wherein the osmosis membrane satisfies a flow rate of 3 to 20 gfd under the condition that ultrapure water is used as raw water and brine (2M NaCl) is used as an inducing solution. 1) A dope solution containing 0.5 to 5% by weight of a sulfonated polysulfone-based polymer and a core solution for hollow formation are simultaneously radiated to the polymer. After air exposure, the solution is impregnated in a coagulation bath and dried to obtain a hollow For example,
2) The hollow fiber is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, and then the excess aqueous solution is washed, and the polyfunctional acid halide compound-containing organic solution is contacted, Amide layer is formed on the surface of the hollow fiber membrane. The method of claim 8, wherein the dope solution comprises a polysulfone-based polymer including polysulfone and polyethersulfone; Polyamide-based polymers; Polyimide-based polymers; Polyester-based polymers; An olefin-based polymer including polypropylene and polyethylene; Halogenated polymers including polybenzimidazole polymers and polyvinylidene dipyrrides; Polyvinylidene fluoride; And 10 to 25% by weight of a polymer selected from the group consisting of polyacrylonitrile and polyacrylonitrile are contained in the organic solvent. The method of claim 8, wherein the core solution comprises a mixing ratio of an organic polar solvent (solvent A): water (solvent B) of 4: 6 to 9: 1 by weight. 11. The method of claim 10, wherein the organic polar solvent is any one selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide. 9. The method of claim 8, wherein the air exposure is performed through an air gap having a length of 1 to 15 cm. The method of claim 8, wherein the temperature of the coagulation bath is maintained at 30 to 70 캜. 9. The method according to claim 8, wherein the hollow fiber has an outer diameter / inner diameter ratio ranging from 1.1 to 3.0. The method according to claim 8, wherein the hollow fiber has a cross-sectional thickness of 30 to 250 탆. 9. The method of claim 8, further comprising the step of immersing the polyamide layer in a solution containing 3 to 40% glycerol and drying after forming the polyamide layer.

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