KR20140003246A - Forward osmosis membrane containing aramid based hollow fiber as a support and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a forward osmosis membrane containing an aramid hollow fiber as a support and a manufacturing method thereof. The forward osmosis membrane of the present invention has a composite membrane structure in which a polyamide layer is laminated on an aramid hollow fiber support, and improves the strength and the heat resistance of the membrane as an aramid hollow fiber is equipped as a support in the conventional membrane structure made of a polymer support, and , therefore, high strength and a heat resistance performance, which are the intrinsic physical properties of aramid, are provided to the membrane. The aramid hollow fiber support is formed in a finger-type pore structure so that water is smoothly flowed in from a source water part to an induction solution through the membrane, and the water permeability toward the osmosis direction and flux are improved. The polyamide layer is coated on the aramid hollow fiber support, which secures anti-fouling and anti-chemical properties and minimizes reverse diffusion of the solute in the induction solution toward the reverse osmosis direction. Further, the forward osmosis membrane has high strength and a heat-resistance performance, which are intrinsic physical properties of aramid, on the membrane, which is applicable to a forward osmosis membrane separation process including a heat process, a forward osmosis membrane separation process in which source water at a high temperature is flowed in, or a membrane process requiring high strength.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive osmosis membrane having an aramid hollow fiber as a support and a method for manufacturing the same. [0002]

More particularly, the present invention relates to a composite membrane structure in which a polyamide layer is laminated on an aramid hollow fiber support, and is characterized by having high strength and heat resistance, which are inherent properties of aramid The performance is imparted to the membrane and the strength and heat resistance of the membrane are improved and the aramid hollow support type is formed into the pore structure of the finger shape so that water flows smoothly from the raw water portion to the induction solution through the membrane, Wherein the polyamide layer is coated on the aramid hollow support so that the stain resistance and chemical resistance are secured and the back diffusion of the inducing solution solute is minimized in the reverse osmosis direction, .

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, solutes should not diffuse from a high concentration solution to a low 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.

The osmosis membrane, which is the opposite of reverse osmosis, is distinguished from the reverse osmosis membrane in membrane structure and physical properties.

In general, the reverse osmosis membrane has a composite membrane structure in which a support is laminated on a nonwoven fabric and a selective layer of polyamide is formed on the support. However, since the reverse osmosis membrane uses pressure in the separation step, And a solid pore structure should be secured. Therefore, when a reverse osmosis membrane that is practically used is applied to a process of a normal osmosis membrane process, that is, a process in which no pressure is generated, water is not leaked at all and an extremely low membrane flow rate of 1 gfd or less is exhibited.

On the other hand, since the osmosis membrane is realized by the osmotic pressure due to the concentration difference in the process in which no pressure acts, water is also transferred by diffusion.

In addition, the reverse osmosis membrane is a process of injecting pressure to exclude salts of raw water and passing only water, which optimizes the physical properties of water flow rate and salt removal rate permeated through the membrane, but the osmosis membrane is an osmotic membrane The research has focused on the flow rate and low despreading property of the low concentration solution flowing toward the high concentration solution.

The present inventors have made efforts to satisfy the physical properties required for the conventional osmosis membrane. As a result, in order to minimize the concentration polarization phenomenon, the inventors have minimized the thickness and increased the porosity to meet the requirements of the osmosis membrane, The present invention has been accomplished by providing a positive osmosis membrane having heat resistance performance.

It is an object of the present invention to provide a novel osmosis membrane comprising aramid hollow fibers as a support.

Another object of the present invention is to provide a method for producing a rigid osmosis membrane in which an aramid hollow support having a high degree of porosity is formed and a polyamide layer is laminated.

The present invention provides a positive osmosis membrane having a composite membrane structure in which a polyamide layer is laminated on an aramid hollow support.

The ortho-osmotic membrane of the present invention has a conductivity value of not more than 1.00 μS / cm or a conductivity value of not more than 0.15 (μS / cm) / min · cm ² at a constant membrane area and has a strength of 4.5 to 7.0 MPa from the aramid hollow- I have.

In the forward osmosis membrane of the present invention, the outer diameter / inner diameter ratio of the aramid hollow fiber is 1.1 to 2.0, and the pore structure is finger-like.

In addition, the thickness of the aramid hollow fiber in the aramid hollow support is preferably 30 to 250 mu m.

The present invention relates to a method for producing an aramid hollow support, comprising the steps of: 1) simultaneously spinning an aramid-containing dope solution and an internal coagulating solution for forming a core, impregnating the coagulation bath after exposure to air,

2) The aramid hollow support is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, followed by washing the excess aqueous solution. 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 purified osmosis membrane of the present invention, the aramid-containing dope solution of step 1) comprises 5 to 20 parts by weight of meta-aramid and 0 to 20 parts by weight of a pore regulating agent with respect to 100 parts by weight of the polar solvent.

In addition, it is preferable that the internal coagulating solution for forming the core in the step 1) has a mixing ratio of an organic polar solvent (solvent A): water (solvent B) of 4: 6 to 9: 1. At this time, the organic polar solvent is any one selected from dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide.

In the method for producing a purified osmosis membrane of the present invention, the air gap is 1 to 15 cm in the step 1) and the temperature of the coagulation bath is maintained at 30 to 70 ° C to form a finger-like pore structure .

Accordingly, in the method for producing a quasi-osmosis membrane of the present invention, the outer diameter / inner diameter ratio of the aramid hollow fiber obtained in the step 1) is in the range of 1.1 to 2.0, and the aramid hollow fiber has the sectional thickness of 30 to 250 탆.

In the method for producing a purified osmosis membrane of the present invention, after the formation of the polyamide layer in the step 2), the step of immersing in a 3 to 40% glycerol-containing solution and drying may be further performed.

The present invention relates to a novel ortho-osmosis membrane comprising a hollow fiber of aramid as a support, wherein a membrane structure composed of a conventional polymer scaffold is replaced with a scaffold for supporting a high strength and heat resistance, And a positive osmosis membrane having improved heat resistance.

The present invention has been made to solve the above-mentioned problems by providing a film having high strength and heat resistance, which is an inherent property of aramid, to the membrane, by optimizing the thickness and porosity of the osmosis membrane to increase the flow rate of the membrane, The present invention can be applied also to the field of a solid osmosis membrane separation process including a thermal process, a process for separating a pure osmosis membrane into which raw water is introduced at a high temperature, or a separation process process requiring a high strength.

FIG. 1 is a scanning electron microscope (SEM) image of a composite membrane obtained by enlarging the cross section of a composite membrane prepared according to Example 1 of the present invention according to the mixing ratio of organic polar solvent: water of 7: 3 for an internal coagulating solution for core formation,
FIG. 2 is a scanning electron microscope (SEM) image of a composite membrane obtained by enlarging the cross section of a composite membrane prepared according to Example 4 of the present invention by a mixing ratio of organic polar solvent: water of 6: 4 for an internal coagulating solution for core formation,
FIG. 3 is a scanning electron microscope (SEM) image of a composite membrane prepared according to Example 5 of the present invention, in which the cross-section of a composite membrane prepared according to a mixing ratio of an organic coagulating solvent: water of 5:
4 is a scanning electron microscope (SEM) image of a composite membrane prepared according to Example 6 of the present invention, in which the cross-section of the composite membrane prepared according to the mixing ratio of the organic coagulating solvent: water of 4:
5 is a scanning electron microscope (SEM) image of a composite membrane obtained by enlarging the cross section of a composite membrane prepared according to Comparative Example 1 of the present invention by 3: 7 in terms of mixing ratio of an internal coagulating solution for forming a core of organic polar solvent: water 500 times.

In order to achieve the above object, the present invention provides a composite membrane-structured positive osmosis membrane in which a polyamide layer is laminated on an aramid hollow support.

The aramid hollow support of the present invention has a high strength due to the inherent property of aramid, so that it can improve the physical strength of the osmosis membrane. More specifically, the positive osmosis membrane has a strength of 4.5 to 7.0 MPa.

The positive osmosis membrane of the present invention achieves a strength of 1.2 to 1.5 times higher than the strength of a conventional osmosis membrane made of cellulose triacetate alone or a conventional reverse osmosis membrane.

In addition, the aramid hollow support has a function of supporting the membrane of the aramid hollow fiber. According to a structural feature that the aramid hollow support of the present invention has a finger-like high pore structure, It is possible to have a smooth water flow and a high water permeability in an osmotic direction.

In addition, the forward osmosis membrane of the present invention improves the physical properties of the membrane, which ensures anti-fouling and chemical resistance while preventing back diffusion of the inducing solution solute in the reverse osmosis direction by forming a polyamide layer on the aramid hollow support.

More specifically, since the quasi-osmotic membrane of the present invention has a conductivity value of 1.00 μS / cm or less per minute or a conductivity value of 0.15 (μS / cm) / min · cm ² or less in membrane area, To prevent diffusion.

Hereinafter, the structure of the osmosis membrane of the present invention will be described in detail.

1) Aramid hollow fiber type support

The aramid hollow-fiber type support in the ortho-osmotic membrane of the present invention can provide a membrane imparted with strength and heat resistance from the high strength and heat resistance inherent to the aramid material.

The outer diameter / inner diameter ratio of the aramid hollow fiber is 1.1 to 2.0, more preferably 1.1 to 1.8. If the ratio is less than 1.1, the film is too thin to have a low strength, and if it exceeds 2.0, the flow rate is undesirably decreased.

Also, the cross-sectional thickness of the aramid hollow fiber is designed for the purpose of increasing the flow rate of the osmosis membrane, preferably 30 to 250 mu m. If it is less than 30 탆, the strength is excessively weak. If it exceeds 250 탆, the effect of improving the flow rate will be insignificant.

From the results of FIGS . 1 to 4 , it can be seen from the results of FIGS . 1 to 4 that the pore structure of the aramid hollow fiber of the present invention is in the form of finger-like pores and is observed at low pore bending. %to be.

2) Polyamide layer

In the ortho-osmotic 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 the polyfunctional amine-containing or alkylated aliphatic amine on the aramid hollow support, As shown in Fig.

More specifically, to an aqueous solution containing a polyfunctional amine selected from metaphenyldiamine, paraphenyldiamine, orthophenyldiamine, piperazine or alkylated piperidine and an alkylated aliphatic amine, a polyfunctional acyl halide, a polyfunctional alcohol A polyfunctional acid halide compound-containing organic solution selected from a polyfunctional isocyanate, a polyfunctional isocyanate, a phosphoryl halide or a polyfunctional isocyanate is contacted to form a polyamide layer by interfacial polymerization among the above 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 an aqueous solution of 0.001 to 8% by weight, more preferably present in 0.01 to 4% by weight.

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.

As described above, according to the structure of the polyamide layer, a high salt rejection rate, chemical resistance, and pH stability can be ensured, and reverse solubility of the solute in the induction solution in the reverse osmosis direction can be prevented.

Hereinafter, a method for producing a purified osmosis membrane of the present invention will be described in detail.

Specifically, the present invention relates to a method for producing an aramid hollow support, comprising the steps of: 1) simultaneously spinning an aramid-containing dope solution and an internal coagulating solution for forming a core, impregnating the coagulation bath after exposure to air,

2) The aramid hollow support is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, followed by washing the excess aqueous solution. 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 purified osmosis membrane of the present invention, the aramid-containing dope solution of step 1) comprises 5 to 20 parts by weight of meta-aramid and 0 to 20 parts by weight of a pore regulating agent with respect to 100 parts by weight of the polar solvent.

The meta-aramid used in the present invention is an aromatic aramid in which a benzene ring is bonded to an amide group at a meta position, and has excellent heat stability and excellent mechanical strength. In addition, the aramid polymer used in the present invention improves the hydrophilicity of the formed film.

In the dope solution of the present invention, the meta-aramid is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the polar solvent. When the meta-aramid content is less than 5 parts by weight, the viscosity of the polymer solution becomes weak, And the physical properties tend to decrease. On the other hand, if it exceeds 20 parts by weight, the viscosity becomes strong, which makes it difficult to form a film and there is a problem of reduction in flow rate.

The porosity regulator contained in the dope solution of the present invention may be any porosity regulator made of a hydrophilic substance having 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 to 20 parts by weight with respect to 100 parts by weight of the polar solvent.

The polar solvent constituting the dope solution may be any one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylsulfoxide (DMSO) and dimethylacetamide Or two or more of them may be used.

In the method for producing a quasi-osmosis membrane of the present invention, the internal coagulating solution for forming the core of the step 1) is preferably a mixture of organic polar solvent (solvent A): water (solvent B) in a mixing ratio of 4: 6 to 9: 1 . 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 organic polar solvent of the coating solution of the present invention is any one selected from dimethylacetamide, N-methyl-2-pyrrolidone or dimethylformamide.

1 to 4 are scanning electron micrographs obtained by observing a cross section of a composite membrane prepared according to an embodiment of the present invention by 500 times magnification, wherein the aramid hollow fiber support is formed into a pore structure in the form of a finger, And exhibits a pore bending degree that is low enough to provide smooth water inflow and high water permeability in the osmotic direction.

5 is a scanning electron microscope (SEM) image of a cross-section of a composite membrane prepared according to Comparative Example 1 of the present invention prepared according to a mixing ratio of organic polar solvent: water of an inlet solvent for forming a core of 3: 7, As a photograph, if the mixing ratio of the organic polar solvent (solvent A): water (solvent B) in the internal coagulating solution for forming the core is out of the range, the desired pore structure of the aramid hollow support can not be obtained.

In the step 1) of the method of manufacturing a quasi-osmosis membrane of the present invention, the thickness and outer / inner diameter ratio of the hollow fiber cross section are adjusted according to the feed rate (rpm) of the dope solution and the inflow amount (cc / min) Preferably, 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 a hollow fiber having a cross-sectional thickness of 30 to 250 mu m.

In the method for producing a purified osmosis membrane of the present invention, the step (2) is a step of forming a polyamide layer, wherein the aramid hollow support formed in step (1) is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine The excess aqueous solution is washed, and the polyamide layer is formed by interfacial polymerization between the compounds by contacting the organic solution containing the polyfunctional acid halide compound.

More specifically, the present invention relates to an aqueous solution containing on the aramid hollow support a multifunctional amine selected from metaphenyldiamine, paraphenyldiamine, orthophenyldiamine, piperazine or alkylated piperidine and an alkylated aliphatic amine, Is contacted with an organic solution containing a polyfunctional acid halide compound selected from a functional acyl halide, a polyfunctional sulfonyl halide or a polyfunctional isocyanate to form a polyamide layer by interfacial polymerization among the above 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 an aqueous solution of 0.001 to 8% by weight, more preferably present in 0.01 to 4% by weight.

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.

In particular, with the polyamide layer formed on the aramid hollow support of the present invention, the positive osmosis membrane of the present invention has a conductivity value of not more than 1.00 μS / cm or 0.15 (μS / cm) / min · cm ² , So that the dissolution of the solute in the inducing solution in the reverse osmosis direction is minimized.

Further, in the method for preparing a purified osmosis membrane of the present invention, after the step 2), a post-treatment step of immersing the formed osmosis membrane in a 3 to 40% glycerol-containing solution and drying it immediately is completed.

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.

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 >

A commercially available 18 wt% liquid meta-aramid solution was diluted with a dimethylacetamide (DMAc) solvent to prepare a 12 wt% aramid-containing dope solution. The bubbles were removed from the 12 wt% aramid-containing dope solution, the dope solution was introduced into one direction of the double nozzle, and the internal coagulating solution for forming the core was introduced into the end of the double nozzle to emit into a hollow fiber. At this time, the internal coagulating solution for forming the core was prepared by mixing 7: 3 by weight of methylpyrrolidone (NMP): water. The feed rate (rpm) of the dope solution and the internal coagulating liquid inflow (cc / min) were adjusted to 6:16 and radiated.

Thereafter, the spinning conditions were set at a temperature of 19.5 DEG C and a humidity of 32% with an air gap set at 3 cm, and then immersed in a solution containing 3% glycerol, a coagulation solution maintained at 40 DEG C, The residual solvent component contained in the hollow fiber was extracted. Then, it was immersed in a 19 wt% NaOCl solution for 10 minutes, washed with distilled water, and then dried under atmospheric conditions at room temperature to produce an aramid hollow fiber.

The prepared aramid hollow fiber was immersed in an aqueous solution containing 2% by weight of meta-phenylenediamine (MPD) for 1 minute, and then the remaining aqueous solution was removed. Then, 1% by weight of trimesoyl chloride (TMC) was immersed four times in an organic solution contained in an isopara solvent ((ISOPAR, Exxon Corp.) Dried to form a polyamide layer, then immersed in 10% basic solution (NaHCO ₃ ) for 3 hours to remove unreacted residues, washed with distilled water, immersed in a solution containing 3% glycerol, To prepare a composite membrane in which a polyamide layer was laminated on the aramid hollow support.

<Example 2>

The procedure of Example 1 was repeated to prepare a composite membrane in which a polyamide layer was laminated on an aramid hollow support, except that an 11 wt% aramid-containing dope solution was used in place of the aramid-containing dope solution of Example 1 Respectively.

<Example 3>

A composite membrane in which a polyamide layer was laminated on an aramid hollow support was produced in the same manner as in Example 1, except that a 10 wt% aramid-containing dope solution was used in place of the aramid-containing dope solution of Example 1 Respectively.

<Example 4>

Example 1 was repeated except that a mixed solvent prepared by mixing methylpyrrolidone (NMP): water in a weight ratio of 6: 4 was used as an internal coagulating solution for forming a core used in Example 1 above. A composite membrane in which a polyamide layer was laminated on an aramid hollow support was prepared.

<Example 5>

Example 1 was repeated except that a mixed solvent prepared by mixing methylpyrrolidone (NMP): water in a weight ratio of 5: 5 was used as an internal coagulating solution for forming a core used in Example 1 above. A composite membrane in which a polyamide layer was laminated on an aramid hollow support was prepared.

<Example 6>

Example 1 was repeated except that a mixed solvent prepared by mixing methylpyrrolidone (NMP): water in a weight ratio of 4: 6 was used as an internal coagulating solution for forming a core used in Example 1 above. A composite membrane in which a polyamide layer was laminated on an aramid hollow support was prepared.

&Lt; Example 7 >

Except that a 12 wt% aramid solution diluted with N-methyl-2-pyrrolidone (NMP) was used instead of the dimethylacetamide (DMAc) solvent used in Example 1, 1 to prepare a composite membrane in which a polyamide layer was laminated on an aramid hollow support.

&Lt; Example 8 >

Except that a 12 wt% aramid solution diluted with dimethylformamide (DMF) was used in place of the dimethylacetamide (DMAc) solvent used in Example 1 above To prepare a composite membrane in which a polyamide layer was laminated on an aramid hollow support.

&Lt; Comparative Example 1 &

Example 1 was repeated except that a mixed solvent prepared by mixing methylpyrrolidone (NMP): water in a weight ratio of 3: 7 was used as an internal coagulating solution for forming a core used in Example 1 above. A composite membrane in which a polyamide layer was laminated on an aramid hollow support was prepared.

Comparative Example 2

The properties were compared using a pure osmosis membrane consisting of cellulose triacetate alone (Hydration Technology Innovation).

&Lt; Comparative Example 3 &

On the porous support of polysulfone, the properties were compared using a commercially available reverse osmosis membrane as a structure in which a polyamide layer was formed.

EXPERIMENTAL EXAMPLE 1 Measurement of Physical Properties of Fixed Osmosis Membrane

 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.

The membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured at a constant pressure (1 bar) through a sample holder having a diameter of 90 mm (manufactured by Woongjin Chemical Co., Ltd.) Were measured. The results are shown in Table 1 below.

2. Measurement of reverse diffusion of membrane

Ultrapure water (osmotic pressure: about 100 atm) was used as the raw water and brine (2M NaCl) was used as the induction solution for the membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 3, (Ultrapure water) was measured by using a conductivity meter to measure the conductivity of a solution between electrodes of a distance of 1 cm from a certain membrane area, and the conductivity was measured in units of the change in conductivity per minute (μS / cm) The degree of diffusion was evaluated. [The value of solid content dissolved in water is expressed in μS / cm × 0.5~0.6 = TDS (Total Dissolved Solids, mg / L).

The results of converting the conductivity values of the membrane area into 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 the composition of the composite membrane in which the polyamide layer was coated on the aramid hollow support of the present invention, the concentration of the aramid-containing dope solution was determined, The membrane had a conductivity value of less than 1.0 μS / cm per minute (membrane area 6.64 cm ² ). In addition, the desalted value of the salt converted to the area was observed to be less than 0.2 μS / cm / min.cm ² , so that the solute of the induction solution did not diffuse in the reverse osmosis direction.

On the other hand, the osmosis membrane of Comparative Example 2 having a single membrane structure composed of a single material of cellulose triacetate, which is a hydrophilic material, showed a much higher flow rate in terms of flow rate. However, It can not be utilized as an osmosis membrane.

Further, when the membrane of Comparative Example 3 in which a polyamide layer was formed on a polysulfone porous support, which is a constitution of a conventional reverse osmosis membrane, was applied to the forward osmosis mode, the reverse diffusion of the salt was extremely low due to the dense pore structure of the reverse osmosis membrane However, the flow rate is remarkably lowered, which is not preferable as a positive osmosis membrane.

<Experimental Example 2> Measurement of porosity of the osmosis membrane

6: 4 (Example 4), 5: 5 (Example 5) and 4: 6 (Example 6) were mixed at a mixture ratio of NMP: water of 7: 3 (Example 1) And 3: 7 (Comparative Example 1) were enlarged 500 times using a scanning electron microscope to observe the pore structure.

As a result, as shown in FIGS. 1 to 5, the pore structure of the aramid hollow support formed in Example 1 and Examples 4 to 6 of the present invention was finger-like and had high porosity The degree of bending of pores was found to be low. On the other hand, in the case of Comparative Example 1, the pore structure was observed to be a distorted shape with a higher degree of bending.

&Lt; Experimental Example 3 > Measurement of film strength

In order to measure the tensile strength of the composite membrane prepared in Example 1, the membrane was pulled and measured in terms of the applied load and the deformation of the test piece. The tensile strength was measured at a speed of 50 mm / min using a tensile strength tester (UTM, manufactured by LLOYD) after cutting the sample into specimens having a length of 15 cm. The results are shown in Table 2 below.

In order to compare the strength of the same shape with that of the hollow fiber of Example 1, the same material of Comparative Example 2 was made into a hollow fiber. The results are shown in Comparative Example 4, and the same polymeric support layer of Comparative Example 3 And the result is shown in Comparative Example 5. For reference, the strength of the flat membrane structure of Comparative Example 2 was 42 MPa, and the strength of the RO flat membrane of Comparative Example 3 was 19 MPa.

From the results shown in the above Table 2, it was confirmed that the aramid hollow support prepared in the example of the present invention had a remarkably high strength of the composite membrane coated with the polyamide layer.

As described above, the ortho-osmotic membrane of the present invention provided a composite osmosis membrane having a polyamide layer laminated on an aramid hollow support.

By providing the aramid hollow fiber as a support, the rigid osmosis membrane of the present invention provides the membrane with high strength and heat resistance, which are intrinsic physical properties of aramid, to provide a membrane having improved strength and heat resistance.

Further, by designing the aramid hollow fiber support having a pore structure having a high porosity in the cleansing osmosis membrane of the present invention, smooth water is introduced into the inducing solution from the raw water portion through the membrane and high water permeability in the osmotic direction is provided. In addition, by coating the polyamide layer on the aramid hollow-fiber support, the forward osmosis membrane of the present invention secures stain resistance and chemical resistance while preventing back diffusion of the inducing solution solute in the reverse osmosis direction, And provided with suitable physical properties and structure.

Furthermore, since the film of the present invention has high strength and heat resistance, which are inherent properties of aramid, the membrane of the present invention is advantageous in that it can be applied to a hydrofluoric acid-free osmosis membrane separation process, a high- It can also be applied to the separation membrane process field.

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 (15)

On an aramid hollow fiber support,
A forward osmosis membrane of a composite membrane structure in which a polyamide layer is laminated. The method according to claim 1, wherein the forward osmosis membrane has a conductivity value of 1.00 μS / cm or less per minute or a conductivity value of 0.15 (μS / cm) / min · cm ² in the membrane area (6.64 cm ² ). Forward osmosis membrane. The forward osmosis membrane according to claim 1, wherein the forward osmosis membrane has a strength of 4.5 to 7.0 Mpa. The forward osmosis membrane according to claim 1, wherein an outer diameter / inner diameter ratio of the aramid hollow yarn is 1.1 to 2.0. The forward osmosis membrane according to claim 1, wherein the aramid hollow fiber support has a finger-like pore structure. The forward osmosis membrane according to claim 1, wherein a cross-sectional thickness of the aramid hollow yarn in the aramid hollow fiber support is 30 to 250㎛. 1) spinning the aramid-containing dope solution and the internal coagulation solution for core formation at the same time, air exposure, impregnating and drying in a coagulation bath to form an aramid hollow fiber support having a finger-shaped pore structure,
2) The aramid hollow fiber support is immersed in an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, and then the excess aqueous solution is washed. A method for producing a forward osmosis membrane, wherein a polyamide layer is formed by interfacial polymerization between the compounds by contacting an organic solution containing a polyfunctional acid halogen compound. The method according to claim 7, wherein the aramid-containing dope solution comprises 5 to 20 parts by weight of metaaramid and 0 to 20 parts by weight of the pore regulator with respect to 100 parts by weight of the polar solvent. The method of claim 7, wherein the internal coagulation solution comprises an organic polar solvent (solvent A): water (solvent B) in a mixing ratio of 4: 6 to 9: 1. The method of claim 9, wherein the organic polar solvent is any one selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide. 8. The method of claim 7, wherein the air gap during the spinning is 1-15 cm in length. The method of claim 7, wherein the temperature of the coagulation bath is maintained at 30 to 70 ℃. The method of claim 7, wherein the ratio of the outer diameter / inner diameter of the aramid hollow yarn is formed in the range of 1.1 to 2.0. The method according to claim 7, wherein the cross-sectional thickness of the aramid hollow yarn is formed to 30 to 250㎛. The method of claim 7, wherein after forming the polyamide layer, further performing a step of drying by immersion in a 3 to 40% glycerol-containing solution is performed.

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