KR101391651B1 - Forward osmosis membrane and manufacturing method thereof - Google Patents

Abstract

TECHNICAL FIELD [0001] The present invention relates to a osmosis membrane having an aramid layer as a support and a method of manufacturing the same.
The present invention provides a positive osmosis membrane comprising a nonwoven fabric layer and an aramid layer or a support composed of an aramid layer alone, wherein the aramid layer is easily controlled in thickness through a solution process, And the pores of the pores of the fingers are formed. Therefore, the forward osmosis membrane provided with the aramid layer of the present invention can smoothly flow water into the induction solution from the raw water portion through the membrane, thereby improving the high water permeability and flow rate in the osmotic direction And the polyamide layer secures stain resistance and chemical resistance and at the same time minimizes the despreading property of the solute of the inducing solution in the reverse osmosis direction and can be usefully used for high concentration seawater separation. Furthermore, since the high strength and heat resistance of the film are imparted to the membrane, it is possible to obtain a high strength and high strength of the osmosis membrane of the present invention. And can be applied to the separation membrane process field.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive osmosis membrane,

More particularly, the present invention relates to a composite membrane structure comprising a nonwoven fabric layer and an aramid layer, or a support composed of an aramid layer alone and a polyamide layer sequentially formed on the support, The thickness of the aramid layer can be easily controlled by a solution process to form a film thickness required for the positive osmosis membrane. Water can be smoothly introduced into the induction solution from the raw water portion by the pores of the finger shape, And a specific amount is achieved and the polyamide layer secures stain resistance and chemical resistance and at the same time satisfies the property of preventing reverse diffusion of the inducing solution solute in the reverse osmosis direction, And a manufacturing method thereof.

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.

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 an aramid layer as a support.

Another object of the present invention is to provide a method for producing a positive osmosis membrane in which the formation of an aramid layer is optimized.

The present invention provides a non-woven fabric layer, an aramid layer, and a polyamide layer; and a forward osmosis membrane composed of the sequentially laminated composite membrane structure.

The present invention also provides a positive osmosis membrane comprising a composite membrane structure in which an aramid layer and a polyamide layer are laminated.

In the forward osmosis membrane of the present invention, the composite film membrane area (24cm ²⁾ it has a conductivity value or 0.375 (μS / cm) / min and the conductivity value of less than ² cm or less per minute 9.0μS / cm from, raw water and 2M 0.0 > gfd < / RTI > under an inductive solution of NaCl or an equivalent level of osmotic pressure.

Preferably, the nonwoven fabric layer has an air permeation rate of 2 cc / cm 2 sec or more, an average pore size of 1 to 600 μm, and a thickness of the nonwoven fabric layer is 20 to 150 μm, A contact angle of at least 0.1 and a maximum of less than 74 degrees.

In the positive osmosis membrane of the present invention, the aramid layer has finger-like pores, and the thickness of the aramid layer is 30 to 250 mu m.

The present invention also relates to a method for producing an aramid composition, comprising the steps of: 1) casting a solution of an aramid-containing polymer in an amount of 8 to 20% by weight on a nonwoven fabric layer to form an aramid layer having a thickness of 30 to 250 μm; 2) Contacting a polyfunctional acid halide compound-containing organic solution with an aqueous solution containing an alkylated aliphatic amine to form a polyamide layer by an interfacial polymerization reaction between the compounds.

The aramid layer is obtained by diluting the aramid-containing polymer solution of 8 to 20% by weight with any polar organic solvent selected from dimethylacetamide, N-methyl-2-pyrrolidone or dimethylformamide, And is formed in a film thickness and pore shape that can satisfy physical properties of the film.

In the method of the present invention, after the polyamide layer is formed, the nonwoven fabric layer may be further stripped to produce a two-layered structure of a normal osmosis membrane.

The present invention can provide a novel osmosis membrane having an aramid layer as a support and a novel osmosis membrane in which a conventional polymer scaffold is replaced by an aramid layer.

The present invention relates to a method for producing an osmosis membrane, which satisfies the requirements of a regular osmosis membrane and particularly imparts a high strength and a heat resistance performance, which are intrinsic properties of aramid, to a osmosis membrane by a manufacturing method that optimizes the thickness and porosity of the structure 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.

1 is a scanning electron microscope photograph of a cross section of a composite membrane according to Example 1 of the present invention,
2 is a scanning electron micrograph of a cross section of a composite membrane of Comparative Example 2 of the present invention.

In order to accomplish the above object, the present invention provides a nonwoven fabric comprising: a nonwoven fabric layer; An aramid layer; And a polyamide layer; and a sequential laminated composite membrane.

Further, since the present invention has a high strength as an intrinsic property of aramid, it can serve as a support layer without a nonwoven fabric layer used for physical strength enhancement. Therefore, the present invention provides a polyamides layer consisting of an aramid layer and a polyamide layer .

At this time, in order to satisfy the requirements of the quasi-osmosis membrane according to the thickness and porosity of each layer, the quasi-osmosis membrane of the present invention has a high porosity on the nonwoven fabric layer having high porosity to achieve high water permeability. Accordingly, the nonwoven fabric layer of the present invention has a thickness of 20 to 150 μm and the aramid layer has a thickness of 30 to 250 μm.

According to this structural feature, the osmosis membrane of the present invention is designed so that water can flow smoothly into the induction solution at the raw water portion, and has high water permeability in the osmotic direction.

Further, by forming the polyamide layer on the support layer which realizes high water permeability of the present invention, it is possible to ensure the stain resistance and chemical resistance, and at the same time to improve the physical properties .

More specifically, because of the conductivity value or 0.375 (μS / cm) / min and conductivity of cm ² or less per minute 9.0μS / cm or less in the forward osmosis membrane membrane area (24cm ²⁾ of the present invention, the salt is reverse To-back direction.

In addition, the ortho-osmotic 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 the same level of osmotic pressure as above.

Hereinafter, the positive osmosis membrane of the present invention will be described in detail according to the constitution.

1) Nonwoven fabric layer

The nonwoven fabric layer of the present invention acts as a support for the membrane.

Preferred materials that may be used in the nonwoven fabric layer of the present invention include synthetic fibers selected from the group consisting of polyester, polypropylene, nylon, and polyethylene; Or a natural fiber including a cellulose-based material. The non-woven 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 any as long as it satisfies an air permeation rate of 2 cc / cm 2 sec sec or more, more preferably 2 to 20 cc / cm 2 sec sec If the material satisfies the air permeation amount, it can be used without any particular limitation. 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 higher the porosity of the nonwoven fabric layer is, the more smoothly the inflow of water into the induction solution in the raw water portion and the high water permeability in the osmotic direction can be ensured.

In general, the nonwoven fabric used for the reverse osmosis membrane exhibits a contact angle of 74 to 90 degrees. However, the nonwoven fabric used in the embodiment of the present invention has high hydrophilicity such that it can be absorbed within 5 seconds within 5 seconds Respectively. Preferably, the hydrophilic property of the material usable as the nonwoven fabric layer in the present invention is 0.1 to 74 degrees , More preferably from 0.1 to 60 degrees. Therefore, by satisfying the high hydrophilicity of the nonwoven fabric layer of the present invention, it is possible to reduce resistance to water and reduce film contamination due to ICP (Internal Concentration Polarization). The internal concentration polarization (ICP) lowers the permeability of the membrane due to the contamination generated inside the membrane. Particularly, when the membrane is contaminated with the ICP in the osmotic membrane operated only by the osmotic pressure due to the naturally occurring concentration difference, Will decrease.

The thickness of the nonwoven fabric layer of the present invention is preferably 20 to 150 占 퐉, and if it is less than 20 占 퐉, the strength and supportability of the entire membrane is insufficient.

2) Aramid layer

The aramid layer 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 aramid layer is formed by a casting method in which a commercially available high concentration solution is diluted with a polar organic solvent and doped on the nonwoven fabric layer. At this time, the preferable dilution concentration that can be performed by the casting method is 8 to 20% by weight of the aramid-containing polymer solution. If it is less than 8% by weight , the separation function is decreased by the low polymer content, It is difficult to form a film due to a high viscosity.

Further, according to the selected preferred organic solvents of the present invention, as set out in the pores of the aramid layer 1, and has a porosity of finger shape (finger-like).

Due to the finger-like pores, the degree of porosity is high and the degree of bending of the pores is low, thereby securing high-flow property.

On the other hand, Fig. 2 shows a cross section of a conventional reverse osmosis membrane, in which the pore of the membrane has a dense structure having a bead shape, so that the flow rate is lowered compared to the membrane of the present invention.

The thickness of the aramid layer of the present invention is preferably 30 to 250 mu m since the thickness of the aramid layer should be minimized in order to meet the increase in flow rate as a requirement for utilizing as a positive osmosis membrane.

3) Polyamide layer

In the 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-containing or alkylated aliphatic amine on the aramid layer, .

Specifically, it is possible to add to the surface of the aramid layer formed on the nonwoven layer 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 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.

More preferably, the polyamide layer of the present invention is prepared by adding, on an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine, an aqueous solution containing 0.01 to 2% by weight of a polyamine salt as a water-soluble additive on a support made of the non- , And an organic solution containing a polyfunctional acid halide compound in contact with each other.

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.

Also, the present invention relates to a method for producing an aramid composition, comprising the steps of: 1) casting an aramid-containing polymer solution of 8 to 20% by weight on a nonwoven fabric layer to form an aramid layer;

2) a step of bringing an organic solution containing a polyfunctional acid halide compound into contact with an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine on the surface of the aramid layer to form a polyamide layer by interfacial polymerization between the compounds The present invention also provides a method for producing a positive osmosis membrane.

The steps of forming the aramid layer in the manufacturing method of the present invention will be described by casting method in which a commercially available high concentration solution is diluted with a polar organic solvent and doped on the nonwoven fabric layer.

By performing the solution process of the casting method, it is easy to control the thickness of the formed aramid layer. At this time, the aramid-containing polymer solution is formed to a thickness of 30 to 250 μm.

In addition, a desirable dilution concentration for application in the casting method solution process is 8 to 20 wt% of an aramid-containing polymer solution. When the content is less than 8 wt%, the separation function is deteriorated due to a low polymer content, %, It is difficult to form a film due to a high viscosity.

At this time, in the embodiment of the present invention, as a solvent for diluting the high-concentration aramid solution, dimethylacetamide, N-methyl-2-pyrrolidone and dimethylformamide are used, And the despreading property of the salt can be ensured. However, the present invention is not limited thereto, and any conventional polar organic solvent may be used.

In particular, the aramid layer of the present invention is formed with finger-like pores, as shown in Fig.

Therefore, if the pores of the conventional polysulfone-based support layer are dense in the form of beads, water can be smoothly introduced into the induction solution from the raw water portion due to the finger-like pores of the aramid layer of the present invention, A high water permeability and a high flow rate are secured.

The above-mentioned osmosis membranes prepared from the above-described processes have a support composed of a nonwoven fabric layer and an aramid layer, thereby satisfying the required thickness and porosity of the osmosis membrane, allowing water to flow smoothly from the raw water section to the induction solution through the membrane, Permeability and flow rate of the polyamide layer can be achieved and the stain resistance and chemical resistance can be secured by the polyamide layer and the back diffusion of the inducing solution solute in the reverse osmosis direction can be minimized, . Further, the hydrogel membrane of the present invention has high strength and heat resistance, which are inherent properties of aramid, imparted to the membrane. Therefore, the membrane of the present invention is advantageous in that it can be applied to a hydrothermal treatment such as a cleansing osmosis membrane separation process, But also in the separation membrane process field.

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 >

A commercially available aramid solution of 18 wt% liquid phase was diluted in a dimethylacetamide (DMAc) solvent to prepare a 12 wt% aramid solution.

Prepared by papermaking The diluted 12 wt% aramid solution was coated on the nonwoven fabric having a porosity of 6.3 cc / cm 2 ㆍ sec air permeability to a thickness of 50 탆 to form an aramid layer. At this time, as a result of measuring the contact angle of the nonwoven fabric 1, the contact time was measured at 80 degrees to 1 degree in 4 seconds, and the average pore size of the nonwoven fabric 1 was 7.5 μm. Thus, an aqueous solution containing 2% by weight of meta-phenylenediamine (MPD) and an organic solution containing 0.1% by weight of trimesoyl chloride (TMC) in an ISOPAR solvent (Exxon Corp.) Interfacial polymerization was performed between the compounds to form a polyamide layer. Then, it was immersed in 10% basic solution (NaHCO ₃ ) for 3 hours and then washed with distilled water to prepare a composite membrane.

≪ Example 2 >

Except that a 12 wt% aramid solution diluted with N-methyl-2-pyrrolidone (NMP) was used instead of the dimethylacetamide solvent of Example 1 to form an aramid layer. 1 to prepare a composite membrane.

≪ Example 3 >

Except that the aramid layer was formed using a 12 wt% aramid solution diluted with dimethylformamide (DMF) in place of the dimethylacetamide solvent of Example 1 To prepare a composite membrane.

<Example 4>

A composite membrane was prepared in the same manner as in Example 1, except that the aramid layer was formed using the 10 wt% aramid solution diluted with the dimethylacetamide solvent of Example 1.

&Lt; Example 5 >

Except that an aramid layer was formed using a 10 wt% aramid solution diluted with a N-methyl-2-pyrrolidone (NMP) solvent in place of the dimethylacetamide solvent of Example 1, 1 to prepare a composite membrane.

&Lt; Example 6 >

Except that the aramid layer was formed using a 10 wt% aramid solution diluted with dimethylformamide (DMF) solvent instead of the dimethylacetamide solvent of Example 1 To prepare a composite membrane.

&Lt; Comparative Example 1 &

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

&Lt; Comparative Example 2 &

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 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 membranes prepared in Examples 1 to 6 and Comparative Examples 1 and 2 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.

&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 a solution between electrodes of a distance of 1 cm from a certain membrane area (24 cm ² ) was measured using a conductivity meter to evaluate the degree of despreading in terms of the change in conductivity per minute (μS / cm) The value of solids dissolved in the solution was expressed as μS / cm × 0.5-0.6 = TDS (Total Dissolved Solids, mg / L).

The results obtained by converting the conductivity values of the membrane area (24 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 above, the membrane compositions prepared in Examples 1 to 6 have a conductivity value of 2.0 μS / cm or less per minute (based on a membrane area of 24 cm ² ) while satisfying excellent flow rate levels, Respectively. Also, the inverse diffusion value of the salt converted to the area was observed as 0.04 to 0.08 (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.

On the other hand, the osmosis membrane of Comparative Example 1 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, in terms of the reverse diffusion of the salt, So that it can not be utilized as a positive osmosis membrane.

In addition, when the membrane of Comparative Example 2 in which a polyamide layer was formed on the polysulfone porous support, which is a constitution of the conventional reverse osmosis membrane, was applied to the forward osmosis mode, the reverse diffusion of the salt due to the dense pore structure of the reverse osmosis membrane was extremely low However, the flow rate is remarkably lowered, which is not preferable as a positive osmosis membrane.

1 is a scanning electron micrograph of a cross section of the composite membrane of Example 1 of the present invention observed at a magnification of 2,000 times, wherein the pores of the aramid layer as the support layer are formed in a finger-like manner, The results are as follows.

On the other hand, FIG. 2 shows a membrane section of Comparative Example 2, which is a constitution of a conventional reverse osmosis membrane, and shows a dense structure to the porosity of the membrane of Example 1. From these pores, it was possible to support the low flow and low salt back diffusion results in Table 1 above.

As described above, the present invention provides a novel osmosis membrane having an aramid layer as a support.

The quasi-osmotic membrane of the present invention comprises a nonwoven fabric layer and an aramid layer, or comprises a support composed of an aramid layer alone, thereby facilitating the inflow of water from the raw water portion into the induction solution through the membrane and providing high water permeability in the osmotic direction. Further, the positive osmosis membrane of the present invention can produce a positive osmosis membrane having less film contamination by the polyamide layer formed on the support layer.

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 (12)

A nonwoven fabric layer;
An aramid layer; And
And a polyamide layer, which are sequentially laminated,
Wherein the aramid layer is formed to a thickness of 30 to 250 탆 by an 8 to 20% by weight of an aramid-containing polymer solution. An aramid layer; And
A polyamide layer; Wherein the composite membrane structure is a laminated structure,
Wherein the aramid layer is formed to a thickness of 30 to 250 탆 by an 8 to 20% by weight of an aramid-containing polymer solution. The positive osmosis membrane according to claim 1 or 2, wherein the positive osmosis membrane has a conductivity variation of 0.375 (μS / cm) / min · cm ² or less per unit area. The positive osmosis membrane according to claim 1 or 2, wherein said 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 induction solution. The positive osmosis membrane according to claim 1, wherein the nonwoven fabric layer has an air permeation rate of 2 cc / cm 2 sec or more. The positive osmosis membrane according to claim 1, wherein the nonwoven fabric layer has an average pore size of 1 to 600 μm. The positive osmosis membrane according to claim 1, wherein the thickness of the nonwoven fabric layer is 20 to 150 μm. The positive osmosis membrane according to claim 1 or 2, wherein the aramid layer has finger-like pores. delete 1) casting an aramid-containing polymer solution prepared by diluting 8 to 20% by weight of aramid in a polar organic solvent on a nonwoven fabric layer to form an aramid layer having a thickness of 30 to 250 탆,
2) a step of bringing an organic solution containing a polyfunctional acid halide compound into contact with an aqueous solution containing a polyfunctional amine or an alkylated aliphatic amine on the surface of the aramid layer to form a polyamide layer by interfacial polymerization between the compounds &Lt; / RTI &gt; The method of claim 10, wherein the polar organic solvent is any one selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide. The method of manufacturing a positive osmosis membrane according to claim 10, wherein the step of peeling the nonwoven fabric layer is further performed after the formation of the polyamide layer.

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