KR102309927B1 - Hollow fiber type Forward Osmosis filtration membrane and the manufacturing method thereby - Google Patents

Abstract

The present invention relates to a hollow fiber type forward osmosis membrane and a method for manufacturing the same, and more particularly, an inner skin in which a polyamide layer is formed on the inner circumferential surface of a support layer of the hollow fiber type forward osmosis membrane, and the support layer has a fine finger-like structure. By manufacturing the separator to include a layer, an inner support layer having a multi-layered finger-like structure, and an outer skin layer having a fine finger-like structure, the possibility of cracks occurring in the separator is reduced and salt removal performance And it relates to a hollow fiber type forward osmosis membrane having an excellent flow rate and a method for manufacturing the same.

Description

Hollow fiber type Forward Osmosis filtration membrane and the manufacturing method thereby}

The present invention relates to a hollow fiber type forward osmosis membrane and a method for manufacturing the same, and more particularly, an inner skin in which a polyamide layer is formed on the inner circumferential surface of a support layer of the hollow fiber type forward osmosis membrane, and the support layer has a fine finger structure (Finger like structure). By manufacturing the separator to include a layer, an inner support layer having a multi-layered finger-like structure, and an outer skin layer having a fine finger-like structure, the possibility of cracks occurring in the separator is reduced and salt removal performance And it relates to a hollow fiber type forward osmosis membrane having an excellent flow rate and a method for manufacturing the same.

Forward osmosis membrane separation is a membrane separation by moving a low concentration solution toward a high concentration solution through the membrane using the osmotic pressure generated by the concentration difference between the two solutions as a driving force.

Therefore, the forward osmosis membrane should facilitate the inflow of water from the raw water to the draw solution through the membrane, and, conversely, maintain a constant concentration of the draw solute while maintaining a high osmotic pressure. For this purpose, the forward osmosis membrane must have high water permeability in the osmosis direction, and it is most important to design so that the solute of the draw solution does not diffuse in the reverse osmosis direction. In addition, the production of a forward osmosis membrane with less membrane contamination should be preceded. Hereinafter, the characteristics that the forward osmosis membrane should have are summarized as follows.

First, in order to improve stain resistance by minimizing internal concentration polarization, the porosity of the support layer in the forward osmosis membrane should be high and the degree of pore curvature should be low.

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

Third, in order to minimize the permeation resistance with water, a hydrophilic material is used.

Fourth, in order to maintain the draw solution at a high concentration, the solute should not be diffused from the high concentration solution to the low concentration solution.

Conventionally, a method for manufacturing a forward osmosis membrane using cellulose triacetate, which is a hydrophilic material, has been proposed. Specifically, on a support layer having a thickness of 25 to 75 μm, a solution having a different concentration in the same material as the support layer is used in 8 to 18 μm. A membrane is prepared by coating a selective layer, and when the membrane is evaluated in forward osmosis (FO) mode using a draw solution, a high flow rate forward osmosis membrane with a flow rate of 11 gfd is presented. However, it is reported that the above-prepared membrane has a disadvantage in that the high concentration of the draw solution diffuses the solute in the direction of the low concentration of raw water. Since it must be maintained above the ideal, there was a problem that it was difficult to apply in reality.

In addition, conventionally, a polysulfone solution is cast on a nonwoven fabric to prepare a membrane at the level of an ultrafiltration membrane, and a polyamide reverse osmosis membrane is manufactured by interfacial polymerization of a polyfunctional amine and a polyfunctional acid halogen compound on the surface of the prepared membrane, and in the above, the nonwoven fabric Only the removed membrane was applied to a forward osmosis (FO) system. As a result of evaluating the physical properties of the membrane in the forward osmosis (FO) mode, a forward osmosis membrane having a salt removal rate that satisfies a flow rate of 0.5 gfd and a salt removal rate of 99% or more was presented. However, although the forward osmosis membrane has a salt removal rate sufficient to separate high-concentration raw water like seawater, it has a low flow rate, so it is difficult to use the separation membrane in reality.

The conventional separation membrane made of the polysulfone-based polymer has excellent mechanical strength, thermal and chemical stability and thus can be used as a material for a membrane. There was a problem with this shortening. Accordingly, in order to improve the basic physical properties of the membrane by further adding a hydrophilic polymer to the polysulfone-based polymer to provide hydrophilicity, a polyamide hr composite membrane in which a polyamide layer is formed on a support layer has been developed.

However, when the conventional hollow fiber type forward osmosis membrane having the above structure is manufactured by including a plurality of hollow fiber type separation membranes, the contact between the membrane and the membrane continues to be located on the surface of the hollow fiber type membrane during the module manufacturing process. If the polyamide layer is damaged or severe, it may be peeled off from the support layer, so there is a problem in that the quality of the hollow fiber membrane module is remarkably deteriorated.

In addition, during module manufacturing and operation, the adhesion between the hollow fiber membranes increases significantly, and as the contact between the membranes and consequent damage and/or the peeling of the polyamide layer is accelerated, the durability is significantly reduced and the use cycle of the separator is shortened. there was. Furthermore, there is a problem that the time and effort put into the process to minimize the problems occurring in the separation membrane manufacturing process significantly lowers workability.

Republic of Korea Patent Application No. 10-2012-0071495 (published on: April 19, 2014) Republic of Korea Patent Application No. 10-2012-0134039 (published on: June, 2014)

The present invention has been devised to solve the above problems, in which a polyamide layer is formed on the inner circumferential surface of a support layer of a hollow fiber type forward osmosis membrane, and the support layer has a fine finger-like structure, an inner skin layer, and a multi-layered finger structure. By manufacturing the separator to include an inner support layer having a finger-like structure and an outer skin layer having a fine finger-like structure, the possibility of cracks occurring in the separator is reduced, and excellent salt removal performance and flow rate are realized. purpose is to

The present invention comprises the steps of (1) preparing a spinning dope containing a solvent and a polysulfone-based polymer; (2) manufacturing a hollow fiber support by simultaneously spinning the spinning stock solution and the internal coagulant through a spinning nozzle having a humidification chamber, and then immersing it in an external coagulating solution; (3) introducing an aqueous amine solution into the hollow fiber support; (4) removing an excess of the aqueous amine solution by injecting air into the hollow fiber support to which the aqueous amine solution has been injected; and (5) adding an interfacial polymerization former to the inside of the hollow fiber support and drying it to form a polyamide layer on the inner circumferential surface of the hollow fiber support. It provides a method for manufacturing a hollow fiber type forward osmosis membrane, characterized in that the object passes through a humidification chamber having a humidity of 80 to 95% and a temperature of 40 to 70° C. before being immersed in an external coagulant.

According to a preferred embodiment of the present invention, in step (1), the solvent is N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc). ) may be at least one selected from the group consisting of.

According to a preferred embodiment of the present invention, the polysulfone-based polymer in step (1) may include polysulfone and sulfonated polysulfone.

According to a preferred embodiment of the present invention, in step (1), the polysulfone-based polymer may include polysulfone and sulfonated polysulfone in a weight ratio of 8 to 10: 1.

According to a preferred embodiment of the present invention, in step (1), the solvent and the polysulfone-based polymer may be included in a weight ratio of 70 to 85: 15 to 30.

According to a preferred embodiment of the present invention, the internal coagulant in step (2) may be mixed with an organic polar solvent and water in a volume ratio of 5:5 to 9:1.

According to a preferred embodiment of the present invention, the organic polar solvent may be at least one selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, glycerol and glycerin. have.

According to a preferred embodiment of the present invention, the spinning nozzle having a humidification chamber in step (2) is a multi-tubular spinning nozzle, discharging the spinning stock solution to the outer tube of the multi-tubular spinning nozzle, and discharging the internal coagulant into a multi-tubular type It can be discharged through the inner tube of the spinning nozzle.

According to a preferred embodiment of the present invention, the temperature of the external coagulation liquid in step (2) may be 30 ℃ ~ 90 ℃.

According to a preferred embodiment of the present invention, the external coagulant in step (2) is from the group consisting of N-methylpyrrolidone, N,N-dimethylacetamide, dimethylsulfoxide, dimethylformamide, glycerol and glycol. One or more selected solvents may be included.

According to a preferred embodiment of the present invention, the distance (air gap) between the spinning nozzle and the external coagulating liquid in step (2) may be 1 cm to 15 cm.

According to a preferred embodiment of the present invention, in step (3), the aqueous amine solution may be introduced into the hollow fiber support at a rate of 100 to 300 ml/min.

According to a preferred embodiment of the present invention, the interfacial polymerization forming agent in step (5) may include a polyfunctional acid halogen compound and an aliphatic hydrocarbon solvent.

According to a preferred embodiment of the present invention, in step (5), the interfacial polymerization forming agent may be introduced into the hollow fiber support at a rate of 100 to 300 ml/min.

According to a preferred embodiment of the present invention, in step (5), the polyamide layer may be formed through interfacial polymerization.

Another aspect of the present invention is a hollow; a polyamide layer formed along the periphery of the hollow; and a support layer formed along the outer periphery of the polyamide layer, wherein the support layer includes an inner skin layer having a fine finger-like structure, an inner support layer having a multi-layered finger-like structure, and a fine finger structure It provides a hollow fiber type forward osmosis membrane comprising an outer skin layer having a (finger-like structure), and the cross-sectional thickness of the inner support layer is 75 to 99% of the total cross-sectional thickness of the support layer.`

According to a preferred embodiment of the present invention, the diameter of the hollow is 600 µm to 900 µm, the cross-sectional thickness of the support layer is 50 µm to 300 µm, and the cross-sectional thickness of the polyamide layer is 0.01 µm to 1 µm. have.

According to a preferred embodiment of the present invention, the fine finger structure of the inner skin layer may have an average horizontal length of 0.1 μm to 2 μm, and an average vertical length of 1 μm to 10 μm.

According to a preferred embodiment of the present invention, the finger structure of the inner layer among the multi-layered finger structures included in the inner support layer has an average horizontal length of 10 μm to 30 μm, and an average vertical length of 20 μm to 60 μm, and Among the multi-layered finger structures included in the inner support layer, the finger structures of the outer layer may have an average horizontal length of 10 μm to 30 μm, and an average vertical length of 30 μm to 60 μm.

According to a preferred embodiment of the present invention, the fine finger structure of the outer skin layer may have a horizontal length of 0.1 μm to 2 μm, and an average vertical length of 1 μm to 10 μm.

According to a preferred embodiment of the present invention, the hollow fiber type forward osmosis membrane may have an average flow rate of 8 gfd or more, and an average specific reverse salt flux (SRSF) of 1 g/L or less.

Another aspect of the present invention provides a forward osmosis membrane module including the hollow fiber type forward osmosis membrane.

The present invention relates to a hollow fiber type forward osmosis membrane and a method for manufacturing the same, and more particularly, an inner skin layer in which a polyamide layer is formed on the inner circumferential surface of a support layer of the hollow fiber type forward osmosis membrane, and the support layer has a fine finger structure. , by manufacturing the separator to include an inner support layer having a multi-layered finger-like structure and an outer skin layer having a fine finger-like structure, thereby reducing the possibility of cracks in the separator and reducing salt removal performance and The flow rate can be improved.

In addition, as the polyamide layer is formed on the inner surface layer of the hollow fiber, a leak of the polyamide layer can be reduced, and even if a plurality of the separators are included in the module, the polyamide layer can Since there is no fear of being damaged, damage to the polyamide layer is prevented due to friction caused by compression between the hollow fiber type forward osmosis membranes, so that the durability of the module can be significantly improved, and thus the use cycle of the module can be increased.

1 is a cross-sectional view of a spinning nozzle having a humidification chamber for manufacturing a hollow fiber type forward osmosis membrane according to the present invention.
2 is a cross-sectional view of a hollow fiber type forward osmosis membrane according to a preferred embodiment of the present invention.
3 is a scanning electron microscope image of observing the inner cross section of the hollow fiber type forward osmosis membrane according to a preferred embodiment of the present invention.
4 is a scanning electron microscope image of observing the outer surface of the support of the hollow fiber type forward osmosis membrane according to a preferred embodiment of the present invention.
5 is a scanning electron microscope image of observing the inner surface of the support of the hollow fiber type forward osmosis membrane according to a preferred embodiment of the present invention.

As described above, in the conventional hollow fiber type forward osmosis membrane, a membrane made of a polyamide layer on the surface of a polysulfone-based polymer may have a leak in the coating layer, which may reduce durability and shorten the use cycle of the membrane. There was a problem in that workability was lowered due to the time and effort put into the process to minimize the above problems.

Accordingly, the present invention comprises the steps of (1) preparing a spinning dope containing a solvent and a polysulfone-based polymer; (2) manufacturing a hollow fiber support by simultaneously spinning the spinning stock solution and the internal coagulant through a spinning nozzle having a humidification chamber, and then immersing it in an external coagulating solution; (3) introducing an aqueous amine solution into the hollow fiber support; (4) removing an excess of the aqueous amine solution by injecting air into the hollow fiber support to which the aqueous amine solution has been injected; and (5) adding an interfacial polymerization former to the inside of the hollow fiber support and drying it to form a polyamide layer on the inner circumferential surface of the hollow fiber support. By providing a method for manufacturing a hollow fiber type forward osmosis membrane, characterized in that the object passes through a humidification chamber having a humidity of 80 to 95% and a temperature of 40 to 70° C. before being immersed in an external coagulant, the solution of the above problem was sought.

Through this, it is possible to reduce the possibility of cracks occurring on the surface of the hollow fiber type forward osmosis membrane and to implement excellent salt removal performance and flow rate. Hereinafter, the present invention will be described in more detail step by step.

In the method for manufacturing a hollow fiber type forward osmosis membrane according to the present invention, the step (1) is a step of preparing a spinning dope, which is a raw material used for manufacturing the hollow fiber support, wherein the spinning dope is a solvent and a polysulfone-based solution. contains polymers. In this case, the solvent is preferably at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc). , more preferably N-methyl-2-pyrrolidone (NMP). In addition, the polysulfone-based polymer may include polysulfone and sulfonated polysulfone, preferably polysulfone and sulfonated polysulfone in a weight ratio of 8 to 10: 1, more preferably is preferably included in a weight ratio of 9 to 10: 1.

In this case, the solvent and the polysulfone-based polymer are preferably included in a weight ratio of 70 to 85: 15 to 30 to prepare a spinning dope, and more preferably, the solvent and the polysulfone-based polymer are 80 to 85: 15 to 20. It is good to be included in the weight ratio.

In the method for manufacturing a hollow fiber type forward osmosis membrane according to the present invention, in the step (2), the spinning stock solution and the internal coagulant are simultaneously spun through a spinning nozzle equipped with a humidification chamber, and then immersed in the external coagulating solution to the hollow fiber. This is a step for preparing a support.

In this case, the internal coagulant may be a mixed solvent containing an organic polar solvent and water, and the organic polar solvent is dimethylacetamide, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, glycerol and glycerin. At least one selected from the group consisting of may be used. The internal coagulant is preferably prepared by mixing an organic polar solvent and water in a volume ratio of 5:5 to 9:1, and when the polar solvent is less than 5, there is a problem in that eccentricity occurs in the hollow of the prepared membrane during spinning. , when it exceeds 9, there is a problem in that it is difficult to form a support while the coagulation of the membrane occurs slowly.

In step (2), the spinning nozzle having a humidification chamber is a multi-tubular spinning nozzle, and the spinning dope is discharged to the outer tube of the multi-tubular spinning nozzle, and the internal coagulant is discharged to the inner tube of the multi-tubular spinning nozzle. .

The radiation spun through the spinning nozzle passes through a humidification chamber of 80 to 95% humidity and 40 to 70° C., preferably 90 to 95% humidity and 50 to 60° C., before being immersed in the external coagulation solution. There is a problem in that it is difficult to form a hollow fiber support from radiation when the humidity and temperature are out of the above ranges.

In addition, the material spun from the spinning nozzle is exposed to air before being immersed in the external coagulating solution. At this time, the hollow fiber pore structure according to the distance between the spinning nozzle and the external coagulating solution, that is, the length of the air gap. can be optimized. Accordingly, the air gap may be 15 cm or less, preferably 1 cm to 15 cm, and more preferably 5 to 10 cm. When the distance between the water surface of the external coagulating liquid and the spinning nozzle is shortened, the physical properties are deteriorated as a result of reacting first by the gases generated at the surface of the coagulating liquid before coagulation occurs, and as a result of being immersed in the external coagulating liquid, the hollow fiber support is rapidly separated due to phase separation. It is not preferable if the distance between the coagulating liquid water surface and the spinning nozzle is too short because the surface is formed to be solid and dense to lower the physical properties, especially the flow rate. If the length of the air gap exceeds 15 cm, the surface of the hollow fiber support is humidified by exposure to air for a long time, and the pores existing in the outer skin layer are formed bulky, which lowers the strength of the separation membrane, so it is not suitable. .

The temperature of the coagulation tank containing the external coagulation liquid is preferably 30 ~ 90 ℃, if the temperature is less than 30 ℃, the size of the pore size on the outer surface of the spun hollow fiber is significantly reduced to obtain the desired water permeability There is a problem, and if it exceeds 90 ℃, there may be a problem in the reproducibility of the membrane as the water in the coagulation tank is evaporated.

In the method for manufacturing a hollow fiber type forward osmosis membrane according to the present invention, the step (3) is a step of injecting an aqueous amine solution into the hollow fiber support, and the aqueous amine solution is processed in a subsequent step to the hollow fiber support A polyamide layer may be formed therein.

The aqueous amine solution is preferably introduced into the hollow fiber support at a rate of 100 to 300 ml/min for 0.5 to 2 minutes, and more preferably at a rate of 150 to 250 ml/min for 1 to 2 minutes. can be put inside. When the aqueous amine solution is introduced into the hollow fiber support at a rate of less than 100 ml/min, the coating solution does not smoothly permeate into the membrane, so there is a problem in that the salt removal performance is lowered, and when the speed exceeds 300 ml/min, When injected into the support, there is a problem in that the coating layer is thickly formed as an excess of the coating solution permeates and the flow rate performance is lowered.

In this case, the aqueous amine solution includes a polyfunctional amine, and the polyfunctional amine may include any one or more of metaphenyldiamine, paraphenyldiamine, orthophenyldiamine, piperazine, or alkylated piperidine.

Specifically, the polyfunctional amine is a material having 2 to 3 amine functional groups per monomer, and may be a polyamine including a primary amine or a secondary amine. In this case, metaphenylenediamine, paraphenylenediamine, orthophenyldiamine, and aromatic primary diamine as a substituent are used as polyamines, and as another example, cycloaliphatic primary diamines such as aliphatic primary diamine and cyclohexenediamine , cycloaliphatic secondary amines such as piperazine, aromatic secondary amines, and the like may be used. More preferably, metaphenylenediamine is used among the polyfunctional amines, and the concentration is preferably in the form of an aqueous solution containing 0.5 to 10 wt% of metaphenylenediamine, more preferably 1 to 4 wt% of metaphenylenediamine It is preferable to use an aqueous solution containing %.

In this case, the polyfunctional amine may further include a compound containing a hydrophilic group in order to improve the basic physical properties of the film, and contact it with an interfacial polymerization former including a polyfunctional acid halugen compound to form polyfunctional amines by interfacial polymerization between the compounds. An amide layer can be formed. The compound containing the hydrophilic group may be present in an aqueous solution in an amount of 0.001 to 8% by weight, more preferably 0.01 to 4% by weight.

The hydrophilic compound that can be added to the aqueous solution containing the polyfunctional amine has at least one hydrophilic functional group selected from the group consisting of a hydroxyl group, a sulfonation group, a carbonyl group, a trialkoxysilane group, an anionic group, and a tertiary amino group. It may be a hydrophilic compound, more preferably a hydrophilic amino compound.

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

The hydrophilic compound having a carbonyl group is from the group consisting of aminoacetaldehyde dimethylacetal, α-aminobutyrolactone, 3-aminobenzamide, 4-aminobenzamide and N-(3-aminopropyl)-2-pyrrolidinone. It may be any one or more selected.

In addition, the hydrophilic compound containing a trialkoxysilane group may be at least one 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-aminoethyl hydrogen sulfate, 3-aminobenzenesulfonic acid, 3-amino-4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid, 3-aminopropylphosphonic acid, 3-amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzo It may be any one or more selected from the group consisting of acid acid, 6-aminohexenoic acid, 3-aminobutanoic acid, 4-amino-2-hydroxybutyric acid, 4-aminobutyric acid, and glutamic acid. have.

In addition, as a hydrophilic compound having one or more tertiary amino groups, 3-(diethylamino)propylamine, 4-(2-aminoethyl)morpholine, 1-(2-aminoethyl)piperazine, 3,3 It may be at least one selected from the group consisting of '-diamino-N-methyldipropylamine and 1-(3-aminopropyl)imidazole.

In the method for manufacturing a hollow fiber type forward osmosis membrane according to the present invention, the step (4) is a step of injecting air into the hollow fiber support to which the aqueous amine solution has been injected to remove the excess aqueous amine solution, the step (3) After removing the amine aqueous solution input from the inside of the hollow fiber support, the polyamide layer may be formed on the outer peripheral surface of the hollow by interfacial polymerization in a subsequent step.

In the method for manufacturing a hollow fiber type forward osmosis membrane according to the present invention, the step (5) is a step of adding an interfacial polymerization former to the inside of the hollow fiber support and drying it to form a polyamide layer on the inner peripheral surface of the hollow fiber support. as,

The interfacial polymerization forming agent is an interfacial polymerization forming agent including a polyfunctional acid halogen compound, and a polyamide layer may be formed on the inner peripheral surface of the hollow fiber support through interfacial bonding with the aqueous amine solution introduced in step (3).

In addition, the material reacting with the polyfunctional amine used in forming the polyamide layer of the present invention may be a polyfunctional acid halogen compound, that is, a polyfunctional acyl halide. Preferably, trimesoyl chloride, isophthaloyl chloride, 5-methoxy-1,3-isophthaloyl chloride, terephthaloyl chloride, etc. may be used alone or in a mixed form. At this time, it is most preferable to use a mixed form in terms of salt removal rate. The polyfunctional acyl halide may be dissolved in an aliphatic hydrocarbon solvent in an amount of 0.01 to 2% by weight, wherein the aliphatic hydrocarbon solvent is a structural isomer of an n-alkane having 5 to 12 carbon atoms and a saturated or unsaturated hydrocarbon having 8 carbon atoms. It is preferable to use a mixture or to use a ring hydrocarbon having 5 to 7 carbon atoms. In the polyfunctional acyl halide-containing solution, 0.01 to 2 wt% of the polyfunctional acyl halide is preferably dissolved in an aliphatic hydrocarbon solvent, and more preferably, 0.05 to 0.3 wt% may be dissolved.

In a preferred embodiment of the present invention, in step (5), the interfacial polymerization forming agent may be introduced into the hollow fiber support at a rate of 100 to 300 ml/min. The interfacial polymerization forming agent is preferably introduced into the hollow fiber support for 0.5 to 2 minutes at a rate of 100 to 300 ml/min, more preferably, the interfacial polymerization forming agent is introduced into the hollow fiber support at a rate of 150 to 250 ml/min for 1 to 2 minutes. It may be injected into the yarn support. When the interfacial polymerization forming agent is introduced into the hollow fiber support at a rate of less than 100 ml/min, the coating solution does not smoothly permeate into the membrane, so there is a problem in that the salt removal performance is lowered, and the rate exceeds 300 ml/min Therefore, when it is introduced into the support, there is a problem in that the coating layer is thickly formed as an excess of the coating solution permeates and the flow rate performance is lowered.

The hollow fiber type forward osmosis membrane according to the present invention, which can be manufactured by the above-described manufacturing method as described above, is a hollow fiber; a polyamide layer formed along the periphery of the hollow; and a support layer formed along the outer periphery of the polyamide layer, wherein the support layer includes an inner skin layer having a fine finger-like structure, an inner support layer having a multi-layered finger-like structure, and a fine finger structure An outer skin layer having a (finger-like structure) is included, and the cross-sectional thickness of the inner support layer is 75 to 99% of the total cross-sectional thickness of the support layer. Hereinafter, the present invention will be described in more detail for each component.

In the hollow fiber type forward osmosis membrane according to the present invention, the diameter of the hollow is 600 µm to 900 µm, the cross-sectional thickness of the support layer is 50 µm to 300 µm, and the cross-sectional thickness of the polyamide layer is 0.01 µm to 1 µm can be

The cross-sectional thickness of the support layer is preferably 50 µm to 300 µm, and when the cross-sectional thickness of the support layer is less than 50 µm, there is a problem in that the thickness of the hollow fiber support layer is thin and mechanical strength cannot be secured, and if the cross-sectional thickness of the support layer is If it exceeds 300 μm, mechanical strength can be secured, but the flow rate decreases due to the thickening of the cross-sectional thickness of the hollow fiber or as the diameter of the hollow fiber itself increases. There may be a problem in that the number of ejaculation osmosis membranes is reduced, and thus the effective filtration area is reduced, thereby lowering the efficiency of the module.

The thickness of the polyamide layer formed along the hollow outer periphery is preferably 0.01 μm to 1 μm. If the thickness of the polyamide layer is less than 0.01 ㎛, there is a problem that it is difficult to serve as a selective layer because the salt removal ability is lowered. This can be.

In the hollow fiber type forward osmosis membrane according to the present invention, the support layer includes an inner skin layer having a fine finger-like structure, an inner support layer having a multi-layered finger-like structure, and a fine finger structure. ), and the cross-sectional thickness of the inner support layer is preferably 75 to 99% of the total cross-sectional thickness of the support layer, and more preferably 80 to 95%. The finger structure of the inner support layer can improve the flow rate of the forward osmosis membrane according to the present invention by including the finger-shaped pores of the elongated shape. When the cross-sectional thickness of the inner support layer is less than 75% of the total cross-sectional thickness of the support layer, there is a problem in that flow rate and SRSF are lowered.

At this time, the fine finger structure of the inner skin layer has an average horizontal length of 0.1 μm to 2 μm, preferably an average vertical length of 1 μm to 10 μm, and more preferably an average horizontal length of 0.5 μm to 1.5 μm. , it is preferable that the average vertical length is 3㎛ ~ 8㎛. When the size of the fine finger structure of the inner skin layer is out of the above range, there is a problem in that the flow rate and SRSF performance of the support and the FO film are rapidly reduced.

In addition, the finger structure of the inner layer among the multi-layered finger structures included in the inner support layer preferably has an average horizontal length of 10 μm to 30 μm, and an average vertical length of 20 μm to 60 μm, more preferably, the average horizontal length. It is preferable that the length is 15 μm to 25 μm, and the average vertical length is 30 μm to 50 μm. Among the multi-layered finger structures included in the inner support layer, the finger structure of the outer layer preferably has an average horizontal length of 10 μm to 30 μm, and an average vertical length of 30 μm to 60 μm, more preferably an average length of 15 It is preferably ~25㎛, and the average vertical length is 40㎛ ~ 60㎛. When the size of the finger structure of the inner support layer is out of the above range, there is a problem in that the flow rate and SRSF performance of the support and the forward osmosis membrane are rapidly reduced.

In addition, the fine finger structure of the outer skin layer has an average horizontal length of 0.1 μm to 2 μm, preferably an average vertical length of 1 μm to 10 μm, and more preferably an average horizontal length of 0.5 μm to 1.5 μm. , it is preferable that the average vertical length is 3㎛ ~ 8㎛. When the size of the fine finger structure of the outer skin layer is out of the above range, there is a problem in that the flow rate and SRSF performance of the support and the FO membrane are rapidly reduced.

The hollow fiber type forward osmosis membrane according to the present invention preferably has an average flow rate of 8 gfd or more, an average SRSF of 1 g/L or less, more preferably an average flow rate of 8-20 gfd, and an average SRSF of 0.01-1 g /L is preferred.

On the other hand, the present invention provides a forward osmosis membrane module including the hollow fiber type forward osmosis membrane according to the present invention described above. The separation membrane module may include a plurality of hollow fiber type forward osmosis membranes, and in the hollow fiber type forward osmosis membrane according to the present invention, the polyamide layer, which is an optional layer, is formed on the inner surface layer of the hollow fiber, thereby cracking the polyamide layer ( leak) can be reduced, and even if a plurality of separation membranes are included in the module, there is no fear of damage to the polyamide layer due to the close contact between the hollow fibers. This can be prevented so that the durability of the module can be significantly improved, and thus the use period of the module can be increased.

The present invention will be described in more detail through the following examples, but the following examples are not intended to limit the scope of the present invention, which should be construed to aid understanding of the present invention.

[ Example ]

Example One. forward osmosis hollow fiber Preparation of Membrane 1

(1) 18 wt% of polysulfone (PSf, Polysulfone) and 2 wt% of sulfonated polysulfone (SPSf) were mixed with 80 wt% of methylpyrrolidone and uniformly mixed at 40°C to prepare a spinning dope.

(2) Using a gear pump, the prepared spinning stock solution was flowed through the outer tube of the nozzle as shown in FIG. 1, and the internal coagulant maintained at 25° C. was flowed through the inner tube of the nozzle to induce hollow formation. At this time, the internal coagulant was made to contain methylpyrrolidone (organic polar solvent) in an amount of 60% by weight and water in an amount of 40% by weight. The solutions discharged from the spinning nozzle passed through a 45 mm high humidification chamber provided in the spinning nozzle, and the humidification chamber formed an atmosphere with a humidity of 90% and a temperature of 60°C. The distance from the spinning nozzle to the surface of the external coagulating solution was 50 mm, and the distance from the humidifying chamber provided in the spinning nozzle to the external coagulating solution was 5 mm. The external coagulation solution contained 100 wt% of water at 60° C., and the spinning material spun from the spinning nozzle was continuously immersed in a coagulation tank containing the external coagulation solution to prepare a hollow fiber support.

(3) The prepared hollow fiber support was put into a module having a diameter of 10 mm and a length of 100 mm, and both ends were potted with an epoxy adhesive to prepare a module. An aqueous solution containing 2 wt% of metaphenylenediamine (MPD) and 98 wt% of water was flowed into the hollow fiber of the prepared module for 1 minute.

(4) Thereafter, air was injected into the hollow fiber to remove excess aqueous amine solution remaining on the inner surface.

(5) Then, an interfacial polymerization former prepared by mixing 0.1 wt% of trimesoyl chloride (TMC) with 99.9 wt% of n-heptane was flowed into the hollow fiber support at a rate of 200 ml/min for 1 minute. Then, it was dried in air for 1 minute to form a polyamide layer by interfacial polymerization. The membrane obtained above was immersed in a 0.2% by weight aqueous sodium carbonate solution at room temperature for 2 hours, and then washed with distilled water to prepare a hollow fiber type forward osmosis membrane.

Example 2. forward osmosis hollow fiber Preparation of separator 2

A hollow fiber type forward osmosis membrane was prepared in the same manner as in Example 1, except that in the step (2), an atmosphere having a humidity of 95% and a temperature of 60° C. was created in the humidification chamber. .

Example 3. forward osmosis hollow fiber Preparation of Separator 3

A hollow fiber type forward osmosis membrane was prepared in the same manner as in Example 1, except that in step (2), an atmosphere having a humidity of 80% and a temperature of 60° C. was created in the humidification chamber. .

comparative example One. forward osmosis hollow fiber Preparation of Membrane 1

A hollow fiber type forward osmosis membrane was prepared in the same manner as in Example 1, except that in the step (2), an atmosphere having a humidity of 75% and a temperature of 60° C. was created in the humidification chamber. .

comparative example 2. forward osmosis hollow fiber Preparation of separator 2

A hollow fiber type forward osmosis membrane was prepared in the same manner as in Example 1, except that in the step (2), an atmosphere having a humidity of 98% and a temperature of 60° C. was created in the humidification chamber. .

comparative example 3. forward osmosis hollow fiber Preparation of Separator 3

A hollow fiber type forward osmosis membrane was manufactured in the same manner as in Example 1, except that a double tube spinning nozzle without a humidification chamber was used in step (2).

comparative example 4. forward osmosis hollow fiber Preparation of Membrane 4

A hollow fiber type forward osmosis membrane was prepared in the same manner as in Example 1, except that the polyamide layer was formed on the outside of the hollow fiber support after step (3).

Experimental example One.

The performance of the hollow fiber type forward osmosis membranes prepared in Examples and Comparative Examples were evaluated and shown in Table 1 below.

1. Membrane flow measurement

After securing the flow path of the hollow fiber membrane by cutting both ends of the solidified epoxy adhesive so that water can flow through the inner diameter of the hollow fiber separator prepared above, raw water flows through the inner diameter of the hollow fiber, and the draw solution flows out of the hollow fiber Then, the flow of water was induced in the direction of the draw solution from the raw water, and the weight of the draw solution was measured before and after time to measure the amount of water per hour. At this time, 2M NaCl was used as the draw solution, and ultrapure water (osmotic pressure about 100 atm) was used as raw water to flow at a constant flow rate (200 ml/min).

) 측정2. SRSF (Specific reverse salt flux,

) measurement

For the separation membrane prepared above, ultrapure water (osmotic pressure about 100 atm) was used as the raw water, brine (2M NaCl) was used as the draw solution, and the electrical conductivity of the salts introduced from the draw solution to the raw water side (ultrapure water) was changed. The degree of reverse diffusion was evaluated in terms of the change in conductivity per minute (μS/cm) by measuring the conductivity of the solution between the electrodes at a distance of 1 cm in a certain membrane area using a conductivity meter.

In addition, for the conductivity value per minute ((μS/cm)/min) obtained above, the SRSF value was obtained by substituting the result of converting the conductivity value with respect to the ^{implemented membrane area (10 cm 2 ) into Equations 1 and 2 below.} measured.

[Formula 1]

σ/2.14 = C _NaCl

In this case, σ is a conductivity value per minute ((μS/cm)/min), and 2.14 is a correlation coefficient between electrical conductivity and concentration. After confirming the concentration by substituting into Equation 1, it was substituted into Equation 2 below.

[Equation 2]

In this case, t is time, C is NaCl concentration, A is membrane area, and V is raw water volume.

Overall support thickness
(μm) inner skin layer thickness
(μm) Inner support layer thickness (㎛) Outer skin layer thickness (㎛) Thickness of inner support layer/Thickness of total support (%) in the humidification chamber
Humidity
(%) in the humidification chamber
Temperature
(℃) average
flux
(gfd) average
SRSF
(g/L) Example 1 110 8 96 6 87 90 60 10.6 0.84 Example 2 118 8 102 8 86 95 60 10.8 1.06 Example 3 103 6 88 5 83 80 60 9.1 0.55 Comparative Example 1 112 14 96 11 79 75 60 5.1 0.39 Comparative Example 2 122 5 109 8 89 99.5 60 14.1 11.9 Comparative Example 3 - - - - - - - eccentricity - Comparative Example 4 110 8 96 6 87 90 60 11.3 2.14

As shown in Table 1, in the case of the forward osmosis hollow fiber membranes prepared in Examples 1 to 3, it was confirmed that the average flow rate was 9 gfd or more and the average SRSF was about 1 g/L or less. However, in the case of the forward osmosis hollow fiber membranes prepared in Comparative Examples 1 to 4, Comparative Example 1 prepared in an atmosphere where the humidity is less than 80% has a problem that it is difficult to use it as a separator because the flow rate is significantly low, and in an atmosphere where the humidity exceeds 95% The prepared Comparative Example 2 has a problem in that it is difficult to perform the role of a separator because the average SRSF is significantly high, and in the case of Comparative Example 3 prepared without a humidification chamber, there is a problem in that eccentricity occurs. In addition, in Comparative Example 4 in which the polyamide layer was formed on the outside of the hollow fiber membrane, the average SRSF was 1 g/L or more, indicating that the performance as a separator was poor, and the polyamide layer could be peeled off during module manufacturing and operation. there is a problem with

Therefore, in the case of the forward osmosis membrane manufactured according to the present invention, when it is manufactured through a humidification chamber with a humidity of 80 to 95% and a temperature of 40 to 70° C., the average flow rate is 8 gfd or more and the average SRSF is 1 g/L or less. It can be seen that represents

Experimental example 2. prepared according to the present invention forward osmosis of separator SEM measurement

The cross section, inner surface and outer surface of the support of the forward osmosis membrane prepared according to the present invention were observed using a scanning electron microscope (SNE-3000, SEC), and the results are shown in FIGS. 3 to 5 below.

As shown in FIG. 3 below, the support layer is an inner skin layer having a fine finger structure, an inner support layer having a multi-layered finger structure, and an outer layer having a fine finger structure. It can be confirmed that the skin layer is included, and the fine finger structure of the inner skin layer has a horizontal length of about 1 μm and a vertical length of about 8 μm, and among the multi-layered finger structures included in the inner support layer, the finger of the inner layer The structure has a width of about 20 μm and a length of about 40 μm, and the finger structures of the outer layer have a width of about 20 μm and a length of 55 μm. It was found that the fine finger structure of the outer skin layer had a horizontal length of about 1 μm and a vertical length of about 6 μm. In addition, it was confirmed that the cross-sectional thickness of the inner support layer was about 75 to 99% of the total cross-sectional thickness of the support layer.

In addition, as shown in FIGS. 4 to 5 below, it was confirmed that the outer surface of the hollow fiber had porosity, and the polyamide layer was formed on the inner surface.

10: inner tube
20: exterior
30: nozzle housing
40: humidification chamber
50: external coagulation tank
60: air gap (air gap)
70: distance between the coagulation bath and the humidification chamber
100: inner tube
200: exterior
300: nozzle housing
400: humidification chamber

Claims (22)

(1) preparing a spinning dope containing a solvent and a polysulfone-based polymer;
(2) simultaneously spinning the spinning stock solution and the internal coagulant through a multi-tubular spinning nozzle having a humidification chamber, and then immersing it in the external coagulating solution to prepare a hollow fiber support;
(3) introducing an aqueous amine solution into the hollow fiber support;
(4) removing an excess of the aqueous amine solution by injecting air into the hollow fiber support to which the aqueous amine solution has been injected; and
(5) forming an interfacially polymerized polyamide layer on the inner circumferential surface of the hollow fiber support by adding an interfacial polymerization former to the inside of the hollow fiber support and drying it;
The radiation emitted through the nozzle in step (2) passes through a humidification chamber with a humidity of 80 to 95% and a temperature of 40 to 70 ℃ before being immersed in the external coagulation solution,
The polysulfone-based polymer comprises polysulfone and sulfonated polysulfone in a weight ratio of 8 to 10: 1,
Discharging the spinning stock solution to the outer tube of the multi-tubular spinning nozzle, and discharging the internal coagulant to the inner tube of the multi-tubular spinning nozzle,
In the step (2), the internal coagulant contains an organic polar solvent and water in a volume ratio of 5:5 to 9:1,
The separation membrane prepared by performing the steps (1) to (5) is hollow; a polyamide layer formed along the periphery of the hollow; and a support layer formed along the outer periphery of the polyamide layer;
The support layer, the support layer, an inner skin layer having a fine finger structure (Finger like structure); an inner support layer having a multi-layered finger structure; and an outer skin layer having a fine finger structure.
According to claim 1,
In step (1), the solvent is at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc). Method for manufacturing a hollow fiber type forward osmosis membrane, characterized in that.
delete delete According to claim 1,
The method of manufacturing a hollow fiber type forward osmosis membrane, characterized in that the solvent and the polysulfone-based polymer in step (1) are included in a weight ratio of 70 to 85: 15 to 30.
delete According to claim 1,
The organic polar solvent is at least one selected from the group consisting of dimethylacetamide, N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, glycerol and glycerin. Way.
delete According to claim 1,
The method of manufacturing a hollow fiber type forward osmosis membrane, characterized in that the temperature of the external coagulation solution in step (2) is 30 ℃ ~ 90 ℃.
According to claim 1,
The external coagulation solution of step (2) includes at least one solvent selected from the group consisting of N-methylpyrrolidone, N,N-dimethylacetamide, dimethylsulfoxide, dimethylformamide, glycerol, and glycol-based solvents. A method for manufacturing a hollow fiber type forward osmosis membrane.
According to claim 1,
The method of manufacturing a hollow fiber type forward osmosis membrane, characterized in that the distance (air gap) between the spinning nozzle and the external coagulant in step (2) is 1 cm to 15 cm.
According to claim 1,
In step (3), the amine aqueous solution is introduced into the hollow fiber support at a rate of 100 to 300 ml/min.
According to claim 1,
In step (5), the interfacial polymerization forming agent comprises a polyfunctional acid halogen compound and an aliphatic hydrocarbon solvent.
According to claim 1,
In the step (5), the interfacial polymerization forming agent is introduced into the hollow fiber support at a rate of 100 to 300 ml/min.
delete hollow;
a polyamide layer having a cross-sectional thickness of 0.01 μm to 1 μm, formed along the periphery of the hollow; and
a support layer having a cross-sectional thickness of 50 μm to 300 μm, formed along the outer periphery of the polyamide layer; and
The support layer, an inner skin layer having an average horizontal length of 0.1 μm to 2 μm, and a fine finger structure having an average vertical length of 1 μm to 10 μm;
an inner support layer having a multi-layered finger structure; and
It includes an external skin layer having an average horizontal length of 0.1 μm to 2 μm, and a fine finger-like structure having an average vertical length of 1 μm to 10 μm,
The support layer comprises a polysulfone-based polymer comprising polysulfone and sulfonated polysulfone in a weight ratio of 8 to 10: 1,
The cross-sectional thickness of the inner support layer is 75 to 99% of the total cross-sectional thickness of the support layer,
The finger structure of the inner layer of the multi-layered finger structure has an average horizontal length of 10 µm to 30 µm, and an average vertical length of 20 µm to 60 µm, and the finger structure of the outer layer among the multi-layered finger structures included in the inner support layer is The average horizontal length is 10 μm to 30 μm, and the average vertical length is 30 μm to 60 μm,
The hollow fiber type forward osmosis membrane is a hollow fiber type forward osmosis membrane, characterized in that the average flow rate is 8 gfd or more, and the average SRSF (Specific reverse salt flux) is 1 g/L or less.
The hollow fiber type forward osmosis membrane according to claim 16, wherein the hollow has a diameter of 600 μm to 900 μm.
delete delete delete delete A forward osmosis membrane module comprising the hollow fiber type forward osmosis membrane according to claim 16 or 17.

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