JP2020138160A - Composite hollow fiber membrane module - Google Patents

Abstract

To provide a composite hollow fiber membrane module with excellent water-permeability.SOLUTION: A composite hollow fiber membrane module 1 includes a housing 2, and a plurality of composite hollow fiber membranes 11 housed in the housing 2. The composite hollow fiber membrane 11 includes a semipermeable membrane layer containing cross-linked polyamide comprising a polyfunctional amine compound and a polyfunctional acid halide compound, and a hollow-fiber porous support layer. The semipermeable membrane layer is in contact with an outer circumferential surface of the support layer. An inner diameter of the housing 2 is 10-200 cm. An effective length of the composite hollow fiber membrane 11 is 0.3-3 m.SELECTED DRAWING: Figure 1

Description

The present invention relates to a composite hollow fiber membrane module.

Membrane separation technology using a semipermeable membrane is attracting attention from the viewpoints of energy saving, resource saving, environmental protection, and the like. Membrane separation techniques using this semipermeable membrane include, for example, semi-permeable membranes such as Nano Filtration (NF) membranes, reverse osmosis (RO) membranes, and forward osmosis (FO) membranes. A membrane having a semipermeable membrane layer having a permeable membrane function is used. Examples of the membrane used in the membrane separation technique using such a semipermeable membrane include a composite membrane provided with not only a semipermeable membrane layer but also a support layer for supporting the semipermeable membrane layer.

Examples of the composite film provided with the semipermeable membrane layer and the support layer include not only a flat membrane-like composite membrane but also a hollow fiber membrane-like composite membrane and the like. Further, when a separation membrane such as a composite membrane is used for water treatment or the like, the separation membrane may be used as a module housed in a housing. As described above, when a separation membrane such as a composite membrane is used for water treatment as a module housed in a housing, a hollow fiber membrane rather than a flat membrane can increase the surface area of the membrane per installation area. Therefore, the hollow fiber membrane is preferably used because it can provide a water treatment system that saves more space.

Examples of the module provided with such a hollow fiber membrane include the modules described in Patent Document 1 and Patent Document 2.

Patent Document 1 describes a core tube connected to a supply port or a discharge port, a hollow fiber membrane group composed of a plurality of hollow fiber membranes, and a resin wall for fixing the core tube and the hollow fiber membrane group at both ends thereof. A hollow fiber membrane element comprising the above, wherein the core tube has a hole only in the vicinity of the first end, which is one end of the hollow fiber membrane group, and the plurality of hollow fiber membranes intersect with each other. It has a cross point group that is spirally wound around the core tube and includes a plurality of cross points that are intersections of the hollow fiber membranes, and is at least in the vicinity of the first end of the hollow fiber membrane group. A hollow fiber membrane module including a hollow fiber membrane element in which the cross point group is present and a container filled with at least one of the hollow fiber membrane elements is described.

Patent Document 2 describes a normal permeation composite hollow fiber membrane module having a hollow fiber bundle composed of a plurality of hollow fiber membranes, wherein the hollow fibers are polymer on the inner surface of the microporous hollow fiber support membrane. A hollow fiber provided with a separation active layer of a polymer thin film, the film area of the hollow fiber membrane bundle is 1 m ² or more, and a scanning electron microscope image obtained by photographing a cross section of the separation active layer in the thickness direction. Described is a module in which the variation coefficient of the average thickness of the separation active layer in the radial direction and the length direction of the hollow fiber membrane bundle calculated by the method of measuring the mass of the separation active layer portion is 0 to 60%. ..

International Publication No. 2015/125755 International Publication No. 2016/027869

As described above, when the composite membrane is used as a module housed in a housing for water treatment or the like, not only the composite membrane is required to have high water permeability, but also the water permeation rate of the module as a whole is required to be high. However, in the case of the conventional hollow fiber membrane module, a sufficiently high water permeation rate may not be obtained as the whole module.

For example, according to Patent Document 1, it is disclosed that it is possible to provide a hollow fiber membrane module in which the flow velocity of the liquid passing outside the hollow fiber membrane is high and the liquid is less likely to stagnate in the element. .. However, even if the hollow fiber membrane module described in Patent Document 1 employs a composite hollow fiber membrane provided with a semipermeable membrane layer containing a crosslinked polyamide, which can be expected to have high performance as the hollow fiber membrane, the entire module. Therefore, it is considered that a sufficiently high water permeation rate cannot be obtained. In the hollow fiber membrane module described in Patent Document 1, as described above, a plurality of hollow fiber membranes are spirally wound around a core tube so as to intersect each other, and the hollow fiber membranes intersect with each other. Includes multiple intersections. It is considered that the semipermeable membrane layer is peeled from the composite hollow fiber membrane at an intersection or the like where the hollow fiber membranes intersect with each other. From this, it is considered that even if the composite hollow fiber membrane is adopted in the hollow fiber membrane module described in Patent Document 1, a sufficiently high water permeation rate cannot be obtained as a whole module.

According to Patent Document 2, it is disclosed that a composite hollow fiber membrane module having a separation active layer having little variation in average thickness in the radial direction and the length direction and exhibiting stable and high performance can be provided. There is. In the composite hollow fiber membrane module described in Patent Document 2, the hollow fiber has a separation active layer of a polymer polymer thin film provided on the inner surface of a microporous hollow fiber support membrane. Since the separation active layer is formed on the inner surface of the support layer in this way, it is considered that the area of the separation active layer becomes insufficient, and a sufficiently high water permeation rate cannot be obtained for the entire module. Be done. Further, Patent Document 2 describes that polysulfone and polyethersulfone are preferable as the material of the microporous hollow fiber support membrane. Since polysulfone and polyethersulfone are not sufficiently hydrophilic, the composite hollow fiber membrane module described in Patent Document 2 in which they are preferably used is not intended to enhance water permeability, but is water permeable. It is thought that the purpose is to reduce sexual variation.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a composite hollow fiber membrane module having excellent water permeability.

As a result of various studies, the present inventors have found that the above object can be achieved by the following invention.

The composite hollow fiber membrane module according to one aspect of the present invention includes a housing and a plurality of composite hollow fiber membranes housed in the housing, and the composite hollow fiber membrane is a polyfunctional amine compound and a polyfunctional acid. A semipermeable membrane layer containing a crosslinked polyamide made of a halide compound and a hollow fiber-like porous support layer are provided, and the semipermeable membrane layer is in contact with the outer peripheral surface of the support layer. The inner diameter is 10 to 200 cm, and the effective length of the composite hollow fiber membrane is 0.3 to 3 m.

According to such a configuration, it is possible to provide a composite hollow fiber membrane module having excellent water permeability. This is considered to be due to the following.

First, since the composite hollow fiber membrane provided in the composite hollow fiber membrane module includes a semipermeable membrane layer containing a crosslinked polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound on the support layer, the semipermeable membrane layer is provided. It is considered that the separation using the above can be preferably performed. Further, by using a hollow thread-like support layer as the support layer, the film area can be made wider than that in the case of making a flat film. Further, since the semipermeable membrane layer is in contact with the outer peripheral surface of the support layer, the semipermeable membrane layer is more than the case where the semipermeable membrane layer is in contact with the inner peripheral surface of the support layer. The area of can be increased. From these facts, the area of the composite hollow fiber membrane provided in the composite hollow fiber membrane module, particularly the area of the semipermeable membrane layer can be increased. Therefore, it is considered that the composite hollow fiber membrane provided in the composite hollow fiber membrane module can preferably perform separation using the semipermeable membrane layer, and thus can realize excellent water permeability.

Further, the composite hollow fiber membrane module obtained by accommodating the composite hollow fiber membrane having an effective length of 0.3 to 3 m in a housing having an inner diameter of 10 to 200 cm is provided in the composite hollow fiber membrane. It is considered that the separation using the obtained semipermeable membrane layer can be preferably performed.

From the above, the composite hollow fiber membrane module can preferably perform separation using the semipermeable membrane layer provided in the composite hollow fiber membrane, and thus has excellent water permeability of the composite hollow fiber membrane. Can be suitably exhibited. Therefore, it is considered that a composite hollow fiber membrane module having a high water permeation rate as a whole module and excellent water permeation performance can be obtained. Further, when the composite hollow fiber membrane module is used, for example, in the forward osmosis method, two solutions having different solute concentrations are brought into contact with each other via the composite hollow fiber membrane to obtain a difference in osmotic pressure caused by the difference in solute concentration. As a driving force, water can be suitably permeated from a dilute solution having a low solute concentration to a concentrated solution having a high solute concentration. When the composite hollow fiber membrane module is used in the forward osmosis method, for example, excellent desalting performance can be exhibited.

Further, in the composite hollow fiber membrane module, the composite hollow fiber membrane preferably has an outer diameter of 0.1 to 2 mm and an inner diameter of 0.05 to 1.5 mm.

According to such a configuration, a composite hollow fiber membrane module having excellent water permeability can be obtained. It is considered that this is because the composite hollow fiber membrane provided in the composite hollow fiber membrane module can exhibit more excellent water permeability.

Further, in the composite hollow fiber membrane module, the ratio of the total cross-sectional area of the plurality of composite hollow fiber membranes to the area of the cross section perpendicular to the longitudinal direction of the composite hollow fiber membrane inside the housing is 10 to 10. It is preferably 65%.

According to such a configuration, a composite hollow fiber membrane module having excellent water permeability can be obtained. It is considered that this is because the excellent water permeability of the composite hollow fiber membrane provided in the composite hollow fiber membrane module can be more preferably exhibited.

Further, the composite hollow fiber membrane module is preferably used in the forward osmosis method.

Since the composite hollow fiber membrane module can be preferably separated by using the semipermeable membrane layer provided in the composite hollow fiber membrane, the composite hollow fiber membrane module is preferably used in the forward osmosis method. Can be done. When the composite hollow fiber membrane module is used in the forward osmosis method, for example, excellent desalting performance can be exhibited.

Further, in the composite hollow fiber membrane module, in the forward osmosis method, the ratio of the water permeation rate in the dry state to the water permeation rate in the wet state is 40 to 100%. Is preferable.

According to such a configuration, the composite hollow fiber membrane module can be used in the forward osmosis method even when the composite hollow fiber membrane provided in the composite hollow fiber membrane module is in a dry state. When the composite hollow fiber membrane module is used by the forward osmosis method, the composite hollow fiber membrane is often used in a wet state. However, when the composite hollow fiber membrane module is transported to the composite hollow fiber membrane module without being filled with liquid, when the composite hollow fiber membrane module is started to be used in the forward osmosis method, the composite hollow fiber membrane is in a dry state. There may be. Even in such a case, the composite hollow fiber membrane module can be used in the forward osmosis method. From this, it is also possible to transport the liquid into the composite hollow fiber membrane module without filling it.

Further, in the composite hollow fiber membrane module, the composite hollow fiber membrane preferably has a water permeation rate of 2 to 100 LMH in a wet state in a forward osmosis method.

According to such a configuration, a composite hollow fiber membrane module having excellent water permeability can be obtained. It is considered that this is because the composite hollow fiber membrane provided in the composite hollow fiber membrane module can exhibit more excellent water permeability.

Further, in the composite hollow fiber membrane module, the contact angle of water with respect to the outer peripheral surface of the support layer is preferably 90 ° or less.

According to such a configuration, a composite hollow fiber membrane module having excellent water permeability can be obtained. This is considered to be due to the following.

First, since the semipermeable membrane layer is in contact with the outer peripheral surface of the hydrophilic support layer, it is considered that the semipermeable membrane layer can be preferably present. Further, it is considered that the support layer is preferably hydrophilized. From these facts, it is considered that the composite hollow fiber membrane provided in the composite hollow fiber membrane module can be more preferably separated by using the semipermeable membrane layer, and can realize more excellent water permeability. From this, it is considered that a composite hollow fiber membrane module having excellent water permeability can be obtained.

Further, when the composite hollow fiber membrane is manufactured using a support layer in which the contact angle of water with respect to the outer peripheral surface is 90 ° or less, in the forward osmosis method, the permeation rate of water in the wet state is relative to the permeation rate of water in the dry state. It is considered that a composite hollow fiber membrane having a water permeation rate ratio of 40 to 100% can be produced. From this point as well, it is considered that a composite hollow fiber membrane module having excellent water permeability can be obtained.

Further, in the composite hollow fiber membrane module, the pressure resistance strength is preferably 0.1 to 3 MPa.

According to such a configuration, a highly durable composite hollow fiber membrane module can be obtained. Therefore, a composite hollow fiber membrane module having not only excellent water permeability but also excellent durability can be obtained.

According to the present invention, it is possible to provide a composite hollow fiber membrane module having excellent water permeability.

FIG. 1 is a schematic view showing an example of a composite hollow fiber membrane module according to an embodiment of the present invention. FIG. 2 is a partial perspective view of the composite hollow fiber membrane provided in the composite hollow fiber membrane module according to the embodiment of the present invention. FIG. 3 is a schematic view showing an example of the layer structure of the composite hollow fiber membrane shown in FIG. FIG. 4 is a schematic cross-sectional view of the composite hollow fiber membrane module shown in FIG.

Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited thereto.

[Hollow fiber membrane module]
The composite hollow fiber membrane module according to the embodiment of the present invention is a composite hollow fiber membrane module in which a plurality of composite hollow fiber membranes are housed in a housing. That is, the composite hollow fiber membrane module is a composite hollow fiber membrane module including the plurality of composite hollow fiber membranes and a housing for accommodating the plurality of composite hollow fiber membranes. The composite hollow fiber membrane includes a semipermeable membrane layer containing a crosslinked polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound, and a hollow fiber-like porous support layer, and the semipermeable membrane layer is the same. It is in contact with the outer peripheral surface of the support layer. Such a composite hollow fiber membrane includes a semipermeable membrane layer containing the crosslinked polyamide, which can be preferably separated using a semipermeable membrane layer, and the area of the semipermeable membrane layer can be increased. .. Then, in the composite hollow fiber membrane module, the composite hollow fiber membrane having an effective length of 0.3 to 3 m is used, and the housing having an inner diameter of 10 to 200 cm is used. Separation using the semipermeable membrane layer provided in the composite hollow fiber membrane can be preferably performed. That is, the composite hollow fiber membrane module is excellent in water permeability.

Specifically, the composite hollow fiber membrane module is a composite hollow fiber membrane in which each composite hollow fiber membrane is sealed in the housing with a sealing agent or the like while the hollow inside of each composite hollow fiber membrane is open. Examples include a filament membrane module. In such a composite hollow fiber membrane module, since the composite hollow fiber membrane is sealed in the housing, the composite hollow fiber membrane is liquid-tightly fixed to the housing. Further, in the composite hollow fiber membrane module, the composite hollow fiber membrane and the housing may be directly adhered and sealed by a sealing agent, or each composite hollow fiber membrane may be sealed by the sealing agent. The composite hollow fiber membrane and the housing may be sealed by being adhered to the tubular case and fixed to the housing. Further, in the composite hollow fiber membrane module, for example, a predetermined number of the plurality of hollow fiber membranes are bundled, the composite hollow fiber membrane bundle is cut to a predetermined length, and the composite hollow fiber membrane bundle is housed (filled) in a housing having a predetermined shape. It is obtained by fixing the end portion to the housing with a sealing agent containing a thermosetting resin such as a polyurethane resin or an epoxy resin. Further, as the composite hollow fiber membrane module, for example, the composite hollow fiber membrane module 1 shown in FIG. 1 and the like can be mentioned. Note that FIG. 1 is a schematic view showing an example of the composite hollow fiber membrane module according to the present embodiment.

As shown in FIG. 1, the composite hollow fiber membrane module 1 includes a housing 2, a plurality of composite hollow fiber membranes 11, a lower end sealing agent 4, and an upper end sealing agent 5. The housing 2 is not particularly limited as long as it can be used as a housing for the hollow fiber membrane module. Specific examples of the housing 2 include a cylindrical body such as a cylinder. The plurality of composite hollow fiber membranes 11 are fixed to the housing 2 by the lower end sealant 4 and the upper end sealant 5 in a state where the lower end and the upper end are open. The lower end sealing agent 4 fixes the lower ends of the plurality of composite hollow fiber membranes 11 to the housing 2, and the upper end sealing agent 5 fixes the upper ends of the plurality of composite hollow fiber membranes 11 to the housing 2. Fixed to body 2. The lower end sealant 4 and the upper end sealant 5 are not particularly limited as long as they are the sealants used for the hollow fiber membrane module. Specific examples of the lower end sealing agent 4 and the upper end sealing agent 5 include a sealing agent containing a thermosetting resin such as a polyurethane resin or an epoxy resin. The housing 2 includes a shell-side introduction port 6, a shell-side outlet 7, a bore-side introduction port 8, and a bore-side outlet 9. The shell-side introduction port 6 and the shell-side outlet 7 are provided on the peripheral surface of the housing 2. A liquid is supplied into the housing 2 from the shell-side introduction port 6, passes through the housing 2, and then discharged from the shell-side outlet 7, so that the liquid is discharged from the housing 2. It is supplied between and the plurality of composite hollow fiber membranes 11, that is, on the shell side. Further, the bore-side introduction port 8 and the bore-side outlet 9 are provided on the lower end surface and the upper end surface of the housing 2, respectively. By supplying a liquid into the housing 2 from the bore-side introduction port 8, passing the liquid through the housing 2, and then discharging the liquid from the bore-side outlet 9, the liquid is made into the plurality of composites. It is supplied to the inside of the hollow fiber membrane 11, that is, to the bore side.

The case where the composite hollow fiber membrane module is used, for example, in the FO method, that is, the case where the composite hollow fiber membrane is used as the FO film will be described. First, when the feed solution (Feed Solution: FS) is supplied to the shell side and the driving solution (Draw Solution: DS) is supplied to the bore side, the water of the supply solution supplied to the shell side is supplied to the bore side. By the supplied driving solution, the osmotic pressure difference is used as a driving force to pull out to the bore side. That is, by bringing the feed solution and the driving solution having different solute concentrations into contact with each other via the composite hollow yarn film, the osmotic pressure difference generated from the solute concentration difference is used as the driving force to change the solute concentration from the supply solution having a low solute concentration. Permeate water into a high driving solution. The supply solution is a liquid to be treated (raw water), and specific examples thereof include seawater. The driving solution will be described later, and specific examples thereof include a relatively high-concentration polymer aqueous solution. Further, the composite hollow fiber membrane module may supply the driving solution to the shell side and the supply solution to the bore side. Further, the membrane separation (membrane filtration) by the composite hollow fiber membrane module is preferably a cross-flow filtration method. Therefore, it is preferable to supply the supply solution and the driving solution so as to use a cross-flow filtration method.

[Composite hollow fiber membrane]
As shown in FIG. 2, the composite hollow fiber membrane 11 is a hollow fiber-like membrane. Further, as shown in FIG. 3, the composite hollow fiber membrane 11 includes a hollow fiber-like porous support layer 12 and a semipermeable membrane layer 13, and the semipermeable membrane layer 13 is the support layer 12. It is in contact with the outer peripheral surface. FIG. 2 is a partial perspective view of the composite hollow fiber membrane provided in the composite hollow fiber membrane module according to the embodiment of the present invention. Further, FIG. 3 is an enlargement of a part A of the composite hollow fiber membrane 11 shown in FIG. 2 to show the layer structure of the composite hollow fiber membrane 11. Note that FIG. 3 is a schematic view showing the positional relationship of the layers and does not particularly represent the relationship of the thickness of the layers.

(Semipermeable membrane layer)
The semipermeable membrane layer 13 contains a cross-permeable polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound, that is, a cross-permeable polyamide formed by polymerizing a polyfunctional amine compound and a polyfunctional acid halide compound. The layer is not particularly limited as long as it functions as a membrane. The content of the crosslinked polyamide in the semipermeable membrane layer 13 is preferably 90 to 100% by mass, and more preferably 100%. That is, the semipermeable membrane layer 13 is preferably made of only the crosslinked polyamide.

The polyfunctional amine compound is not particularly limited as long as it is a compound having two or more amino groups in the molecule. Examples of the polyfunctional amine compound include aromatic polyfunctional amine compounds, aliphatic polyfunctional amine compounds, and alicyclic polyfunctional amine compounds. Examples of the aromatic polyfunctional amine compound include phenylenediamines such as m-phenylenediamine, p-phenylenediamine, and o-phenylenediamine, 1,3,5-triaminobenzene and 1,3,4-. Triaminobenzene such as triaminobenzene, diaminotoluene such as 2,4-diaminotoluene and 2,6-diaminotoluene, 3,5-diaminobenzoic acid, xylylenediamine, and 2,4-diaminophenol dihydrochloride ( Amidol) and the like. In addition, examples of the aliphatic polyfunctional amine compound include ethylenediamine, proprenicamine, and tris (2-aminoethyl) amine. Examples of the alicyclic polyfunctional amine compound include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, and 4-aminomethylpiperazine. Can be mentioned. Among these, aromatic polyfunctional amine compounds are preferable, and phenylenediamine is more preferable. Further, as the polyfunctional amine compound, the above-exemplified compounds may be used alone, or two or more kinds may be used in combination.

The polyfunctional acid halide compound (polyfunctional acid halide) removes two or more hydroxyl groups from the acid contained in the polyfunctional organic acid compound having two or more acids such as carboxylic acid in the molecule, and the hydroxyl group is formed. The compound is not particularly limited as long as it is a compound in which a halogen is bound to the removed acid. The polyfunctional acid halide compound may be divalent or higher, and preferably trivalent or higher. In addition, examples of the polyfunctional acid halide compound include polyfunctional acid fluoride, polyfunctional acid chloride, polyfunctional acid bromide, and polyfunctional acid iodide. Among these, a polyfunctional acid chloride (polyfunctional acid chloride compound) is preferably used because it is most easily obtained and has high reactivity, but is not limited to this. In addition, the polyfunctional acid chloride will be exemplified below, and examples of the polyfunctional acid halide other than the polyfunctional acid chloride include those in which the following-exemplified chloride is changed to another halide.

Examples of the polyfunctional acid chloride compound include aromatic polyfunctional acid chloride compounds, aliphatic polyfunctional acid chloride compounds, and alicyclic polyfunctional chloride compounds. Examples of the aromatic polyfunctional acid chloride compound include trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonic acid trichloride, and benzenedisulfonic acid dichloride. Can be mentioned. Examples of the aliphatic polyfunctional acid chloride compound include propandicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propantricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, and glutalyl. Examples thereof include chloride and adipoil chloride. Examples of the alicyclic polyfunctional chloride compound include cyclopropantricarboxylic acid trichloride, cyclobutanetetracarboxylic acid tetrachloride, cyclopentanetricarboxylic acid trichloride, cyclopentanetetracarboxylic acid tetrachloride, cyclohexanetricarboxylic acid trichloride, and tetra. Examples thereof include hydrofurantetracarboxylic acid tetrachloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, tetrahydrofurandicarboxylic acid dichloride and the like. Among these, aromatic polyfunctional acid chloride compounds are preferable, and trimesic acid trichloride is more preferable. Further, as the polyfunctional acid halide compound, the above-exemplified compounds may be used alone or in combination of two or more.

(Support layer)
As described above, the support layer 12 is not particularly limited as long as it is hollow filamentous and porous. Further, the support layer 12 may be made hydrophilic by containing a hydrophilic resin. The hydrophilic resin contained in the support layer 12 is preferably crosslinked. That is, it is preferable that the support layer 12 contains a crosslinked hydrophilic resin in a hollow filament-like porous base material. The crosslinked hydrophilic resin may be contained in the entire support layer 12 or a part of the support layer 12, but in that case, it is contained in the outer peripheral surface of the support layer 12. It is more preferable that the support layer 12 is contained in the outer peripheral surface of the support layer 12 and is further contained in a portion other than the outer peripheral surface of the support layer 12.

The hollow fiber-like porous base material is not particularly limited as long as it is a base material made of a material capable of forming a hollow fiber membrane. Examples of the components contained in the support layer 12 (components constituting the hollow filament-like porous base material) include acrylic resin, polyacrylonitrile, polystyrene, polyamide, polyacetal, polycarbonate, polyphenylene ether, polyphenylene sulfide, polyethylene terephthalate, and the like. Polytetrafluoroethylene, polyvinylidene fluoride, polyetherimide, polyamideimide, polychloroethylene, polyethylene, polypropylene, polyketone, crystalline cellulose, polysulfone, polyphenylsulphon, polyethersulfon, acryliconitrile butadiene styrene (ABS) resin, And acryliconitrile styrene (AS) resin and the like. Of these, polyvinylidene fluoride, polysulfone, and polyethersulfone are preferable from the viewpoint of excellent pressure resistance. Further, as the component contained in the holding layer 12 (the component constituting the hollow filament-like porous base material), the above-exemplified resin may be used alone, or two or more kinds may be used in combination. ..

The hydrophilic resin is not particularly limited as long as it is a resin capable of making the support layer 12 hydrophilic by being contained in the hollow filament-like porous base material. Examples of the hydrophilic resin include cellulose acetate-based polymers such as cellulose, cellulose acetate and cellulose triacetate, vinyl alcohol-based polymers such as polyvinyl alcohol and polyethylene vinyl alcohol, polyethylene glycol-based polymers such as polyethylene glycol and polyethylene oxide, and polyacrylics. Examples thereof include acrylic acid-based polymers such as sodium acid acid, and polyvinylpyrrolidone-based polymers such as polyvinylpyrrolidone. Among these, vinyl alcohol-based polymers and polyvinylpyrrolidone-based polymers are preferable, and polyvinyl alcohol and polyvinylpyrrolidone are more preferable. Further, as the hydrophilic resin, the above-exemplified resin may be used alone, or two or more kinds may be used in combination. Further, the hydrophilic resin may contain hydrophilic single molecules such as glycerin and ethylene glycol, or may be polymers of these, and may contain these as a copolymerization component with the resin. There may be.

The cross-linking of the hydrophilic resin may be carried out as long as the hydrophilic resin is cross-linked to reduce the solubility of the hydrophilic resin in water, and examples thereof include cross-linking in which the hydrophilic resin is insolubilized so as not to be dissolved in water. Examples of the cross-linking of the hydrophilic resin include an acetalization reaction using formaldehyde and an acetalization reaction using glutaraldehyde when polyvinyl alcohol is used as the hydrophilic resin. When polyvinylpyrrolidone is used as the hydrophilic resin, for example, a reaction with a hydrogen peroxide solution can be mentioned. When the degree of cross-linking of the hydrophilic resin is high, it is considered that elution of the hydrophilic resin from the composite hollow fiber membrane can be suppressed even if the composite hollow fiber membrane is used for a long period of time. Therefore, it is considered that the peeling of the semipermeable membrane layer and the support layer can be suppressed for a long period of time.

The support layer 12 has an inclined structure in which the pores of the support layer 12 gradually increase from the outer surface toward the inner peripheral surface, that is, an inclined structure in which the pores of the support layer 12 gradually decrease from the inner surface toward the outer surface. Is preferable. The inclined structure in which the pores of the support layer 12 gradually increase from the outer surface toward the inner peripheral surface means that the pores existing on the outer surface are smaller than the pores existing on the inner peripheral surface of the support layer 12. The internal pores have a structure equal to or greater than the pores existing on the outer peripheral surface and equal to or less than the pores existing on the inner peripheral surface.

In the composite hollow fiber membrane 11, the semipermeable membrane layer 13 is provided in contact with the outer peripheral surface of the support layer 12 as described above. This outer peripheral surface is a so-called dense surface.

The contact angle of water with respect to the outer peripheral surface (dense surface) of the support layer 12 is preferably 90 ° or less, more preferably 65 ° or less, and further preferably 10 to 65 °. By adjusting the contact angle of water with respect to the outer peripheral surface of the support layer 12, the water permeability of the composite hollow fiber membrane 11, particularly the water permeability in a dry state can be adjusted. When the composite hollow fiber membrane is manufactured using a support layer in which the contact angle of water with respect to the outer peripheral surface is 90 ° or less, in the forward osmosis method, water in a dry state is compared with the permeation rate of water in a wet state. It is considered that a composite hollow fiber membrane having a permeation rate ratio of 40 to 100% can be produced. From this point as well, it is considered that a composite hollow fiber membrane module having excellent water permeability can be obtained. Further, if the contact angle is too large, the hydrophilicity of the support layer is insufficient, and the semipermeable membrane layer tends not to be suitably formed on the support layer. This is thought to be due to the following. When forming the semipermeable membrane layer, first, an aqueous solution of a polyfunctional amine compound which is a raw material of a crosslinked polyamide polymer constituting the semipermeable membrane layer is brought into contact with the dense surface side of the support layer. At this time, if the contact angle of water with respect to the outer peripheral surface (dense surface) is 90 ° or less, the aqueous solution of the polyfunctional amine compound sufficiently soaks into the dense surface side of the support layer. In this state, when the organic solvent of the polyfunctional acid halide compound which is the raw material of the crosslinked polyamide polymer is brought into contact with the dense surface side of the support layer and then dried, the polyfunctional amine compound and the polyfunctional amine compound are dried. A semipermeable membrane layer containing the crosslinked polyamide polymer is formed so that the acid halide compound is interfacially polymerized and comes into contact with the dense surface of the support layer. On the other hand, if the contact angle of water with respect to the outer peripheral surface (dense surface) is too large, the aqueous solution of the polyfunctional amine compound does not sufficiently soak into the dense surface side of the support layer, and the interfacial polymerization is preferable. Tends to be unable to do. Therefore, there is a tendency that the semipermeable membrane layer cannot be suitably formed on the support layer. Further, when the contact angle of water with respect to the outer peripheral surface (dense surface) is too large, even if the semipermeable membrane layer is formed, the semipermeable membrane layer is peeled off from the support layer. It also tends to be easy.

The support layer 12 is preferably hydrophilic so that the contact angle of water with respect to the outer peripheral surface is 90 ° or less as described above, but the support layer 12 is totally hydrophilic. It is more preferable to be there.

Whether or not the support layer is hydrophilized can be determined by performing IR (Infrared Spectroscopy) analysis, XPS (X-ray Photoelectron Spectroscopy) analysis, or the like on the support layer. For example, by performing the above analysis on each of the inner surface and the outer surface of the support layer and the inner surface from which the support layer is cut out, it can be determined whether or not the hydrophilic resin is present at each position. .. Then, if the hydrophilic resin is present over the entire support layer, it can be seen that the entire support layer is hydrophilic. That is, if the presence of the hydrophilic resin can be confirmed on all of the inner surface, the outer surface, and the inside of the support layer, it can be seen that the entire support layer is hydrophilic.

The fractionated particle size of the support layer 12 is preferably 0.001 to 0.3 μm, more preferably 0.001 to 0.2 μm, and 0.001 to 0.1 μm. Is even more preferable. That is, the pores existing on the outer peripheral surface (dense surface) are preferably pores in which the fractionated particle diameter of the support layer is within the above range. If the fractionated particle diameter is too large, the pores existing on the dense surface tend to be large, and the semipermeable membrane layer tends not to be suitably formed on the dense surface. That is, the entire dense surface cannot be covered with the semipermeable membrane layer, and there is a tendency that separation by the semipermeable membrane layer cannot be preferably performed. When the composite hollow fiber membrane is used as, for example, a forward osmosis (FO) membrane, it tends to be difficult to obtain sufficient desalting performance. On the other hand, if the fractionated particle size is too small, separation by the semipermeable membrane layer can be preferably performed, and for example, although desalination performance can be sufficiently exhibited, the permeation flux tends to decrease. Therefore, when the fractionated particle diameter is within the above range, both separation by the semipermeable membrane layer and permeability can be achieved. The fractionated particle size refers to the particle size of the smallest particles that can block the passage of the support layer. Specifically, for example, the ratio of blocking permeation by the support layer (blocking rate by the support layer) is 90%. The diameter of the particles and the like at the time of

The average diameter of the pores formed on the inner peripheral surface of the support layer 12 is preferably 1 to 50 μm, more preferably 1 to 30 μm, and even more preferably 1 to 20 μm. If this average diameter is too small, the degree to which the pores of the support layer in the inclined structure of the support layer increase from the outer peripheral surface to the inner peripheral surface is too low, and the permeability tends to be insufficient. .. On the other hand, if the average diameter is too large, the strength of the support layer tends to be insufficient.

The pressure resistance of the support layer 12 is preferably 0.3 MPa or more and less than 5 MPa, more preferably 0.3 MPa or more and less than 4 MPa, and further preferably 0.3 MPa or more and less than 3 MPa. This pressure resistance is the maximum pressure that can maintain the shape of the support layer when pressure is applied from the outside of the support layer and the maximum pressure that can maintain the shape of the support layer when pressure is applied from the inside of the support layer. The lower pressure. The maximum pressure that can maintain the shape of the support layer when pressure is applied from the outside of the support layer is, for example, the pressure when pressure is applied from the outside of the support layer and the support layer is crushed. The maximum pressure that can maintain the shape of the support layer when pressure is applied from the inside of the support layer is, for example, the pressure when pressure is applied from the inside of the support layer and the support layer bursts. If the pressure resistance is too low, the durability of the composite hollow fiber membrane tends to be insufficient in practical operation using the composite hollow fiber membrane. The higher the pressure resistance, the more preferable, but the pressure resistance that is too high may not be necessary in practice.

The method for producing the support layer 12 is not particularly limited as long as the hollow fiber membrane having the above configuration can be produced. Examples of the method for producing the hollow fiber membrane include a method for producing a porous hollow fiber membrane. As a method for producing such a porous hollow fiber membrane, a method using phase separation is known. Examples of the method for producing a hollow fiber membrane utilizing this phase separation include a nonsolvent integrated phase separation method (NIPS method) and a heat-induced phase separation method (Thermally Induced Phase Separation: TIPS method). Can be mentioned.

The NIPS method is a solvent of a polymer stock solution in which a uniform polymer stock solution in which a polymer is dissolved in a solvent is brought into contact with a non-solvent in which the polymer is not dissolved, and the concentration difference between the polymer stock solution and the non-solvent is used as a driving force. This is a method of causing a phase separation phenomenon by substituting with a non-solvent. In the NIPS method, the pore size of the formed pores generally changes depending on the solvent exchange rate. Specifically, the slower the solvent exchange rate, the coarser the pores tend to be. Further, in the production of the hollow fiber membrane, the solvent exchange rate is the fastest on the contact surface with the non-solvent and becomes slower toward the inside of the membrane. Therefore, the hollow fiber membrane produced by the NIPS method has an asymmetric structure in which the vicinity of the contact surface with the non-solvent is dense and the pores are gradually coarsened toward the inside of the membrane.

Further, in the TIPS method, a phase separation phenomenon occurs by dissolving a polymer in a poor solvent which can be dissolved at a high temperature but cannot be dissolved when the temperature is lowered at a high temperature and cooling the solution. It is a way to make it. Since the heat exchange rate is generally faster than the solvent exchange rate in the NIPS method and it is difficult to control the rate, the TIPS method tends to form uniform pores in the film thickness direction.

The method for producing the hollow fiber membrane (support layer) is not particularly limited as long as the hollow fiber membrane can be produced. Specifically, as this manufacturing method, the following manufacturing methods can be mentioned. The manufacturing method includes a step of preparing a film-forming stock solution containing a resin and a solvent constituting a hollow fiber membrane (preparation step), a step of extruding the film-forming stock solution into a hollow fiber shape (extrusion step), and extruding. Examples thereof include a method including a step (formation step) of forming a hollow fiber membrane by coagulating a hollow fiber-shaped membrane-forming stock solution.

(Composite hollow fiber membrane)
If the composite hollow fiber membrane is a support layer provided in the composite hollow fiber membrane, the support layer supports the semipermeable membrane layer and further prevents separation by the semipermeable membrane layer. There is no particular limitation. That is, the composite hollow fiber membrane includes a semipermeable membrane layer and a support layer containing a crosslinked polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound, and the support layer preferably functions as a semipermeable membrane layer. Any support layer that can be used for Further, the support layer does not have to be the semipermeable membrane layer containing the crosslinked polyamide described in the following examples, but may be a support layer that preferably exhibits the functions of the respective semipermeable membrane layers.

The outer diameter R1 of the composite hollow fiber membrane is preferably 0.1 to 2 mm, more preferably 0.2 to 1.5 mm, and even more preferably 0.3 to 1.5 mm. If the outer diameter is too small, the inner diameter of the composite hollow fiber membrane may also be too small, and in this case, the liquid passage resistance of the hollow portion becomes large, and a sufficient flow rate tends not to be secured. When the composite hollow fiber membrane is used as a forward osmosis membrane or the like, the driving solution tends to be unable to flow at a sufficient flow rate. Further, if the outer diameter is too small, the withstand voltage with respect to the pressure applied to the outside tends to decrease. Further, if the outer diameter is too small, the film thickness of the composite hollow fiber membrane may be too thin, and in this case, the strength of the composite hollow fiber membrane tends to be insufficient. That is, there is a tendency that a suitable pressure resistance cannot be realized. Further, if the outer diameter is too large, when a hollow fiber membrane module in which a plurality of composite hollow fiber membranes are housed is configured, the number of hollow fiber membranes housed in the case is reduced. The membrane area is reduced, and as a hollow fiber membrane module, there is a tendency that a sufficient flow rate cannot be secured in practical use. If the outer diameter is too large, the withstand voltage against pressure applied from the inside tends to decrease. Therefore, when the outer diameter of the composite hollow fiber membrane is within the above range, the composite hollow fiber membrane can be preferably separated by a semipermeable membrane having sufficient strength and excellent permeability.

The inner diameter R2 of the composite hollow fiber membrane is preferably 0.05 to 1.5 mm, preferably 0.1 to 1 mm, and even more preferably 0.2 to 1 mm. If the inner diameter is too small, the liquid passage resistance of the hollow portion becomes large, and there is a tendency that a sufficient flow rate cannot be secured. When the composite hollow fiber membrane is used as a forward osmosis membrane or the like, the driving solution tends to be unable to flow at a sufficient flow rate. Further, if the inner diameter is too small, the outer diameter of the composite hollow fiber membrane may also be too small, and in this case, the pressure resistance strength against the pressure applied to the outside tends to decrease. Further, if the inner diameter is too large, the outer diameter of the composite hollow fiber membrane may also be too large. In this case, when a hollow fiber membrane module in which a plurality of composite hollow fiber membranes are housed in a housing is configured, the housing Since the number of hollow fiber membranes to be accommodated in the body is not small, the membrane area of the hollow fiber membrane is reduced, and there is a tendency that a sufficient flow rate cannot be secured practically as a hollow fiber membrane module. If the inner diameter is too large, the outer diameter of the composite hollow fiber membrane may also be too large. In this case, the pressure resistance strength against the pressure applied from the inside tends to decrease. Further, if the inner diameter is too large, the film thickness of the composite hollow fiber membrane may become too thin, and in this case, the strength of the composite hollow fiber membrane tends to be insufficient. That is, there is a tendency that a suitable pressure resistance cannot be realized. Therefore, when the inner diameter of the composite hollow fiber membrane is within the above range, the composite hollow fiber membrane can be preferably separated by a semipermeable membrane having sufficient strength and excellent permeability.

The film thickness T of the composite hollow fiber membrane is preferably 0.02 to 0.3 mm, more preferably 0.05 to 0.3 mm, and preferably 0.05 to 0.25 mm. Is even more preferable. If the film thickness is too thin, the strength of the composite hollow fiber membrane tends to be insufficient. That is, there is a tendency that a suitable pressure resistance cannot be realized. Further, if the film thickness is too thick, the permeability tends to decrease. Further, if the film thickness is too thick, internal concentration polarization in the support layer is likely to occur, and there is a tendency to hinder separation by the semipermeable membrane. That is, when the composite hollow fiber membrane is used as a forward osmosis membrane or the like, the contact resistance between the driving solution and the supply solution increases, so that the permeability tends to decrease. Therefore, when the film thickness of the composite hollow fiber membrane is within the above range, the composite hollow fiber membrane has sufficient strength, is excellent in permeability, and can be preferably separated by a semipermeable membrane.

The film thickness of the semipermeable membrane layer 13 is the thickness formed by the following interfacial polymerization. Specifically, the film thickness of the semipermeable membrane layer is 1 to 10000 nm, more preferably 1 to 5000 nm, and even more preferably 1 to 3000 nm. If the film thickness is too thin, separation by the semipermeable membrane layer tends to be difficult. When the composite hollow fiber membrane is used as a forward osmosis membrane or the like, sufficient desalting performance cannot be exhibited, and separation by a semipermeable membrane layer cannot be preferably performed such that the salt backflow rate increases. Tend. It is considered that this is because the semipermeable membrane layer is too thin to sufficiently perform the function of the semipermeable membrane layer, or the semipermeable membrane layer cannot sufficiently cover the support layer. .. Further, if the film thickness is too thick, the permeability tends to decrease. It is considered that this is because the semipermeable membrane layer is too thick and the water permeation resistance becomes large, so that it becomes difficult for water to permeate.

The thickness of the support layer 12 is the difference between the thickness of the composite hollow fiber membrane and the thickness of the semipermeable membrane layer 13, and is specifically 0.02 to 0.3 mm, which is 0. It is more preferably 05 to 0.3 mm, and even more preferably 0.05 to 0.25 mm. The film thickness of the support layer is almost the same as the film thickness of the composite hollow fiber membrane because the semipermeable membrane layer is very thin as compared with the support layer. If the film thickness is too thin, the strength of the composite hollow fiber membrane tends to be insufficient. That is, there is a tendency that a suitable pressure resistance cannot be realized. Further, if the film thickness is too thick, the permeability tends to decrease. Further, if the film thickness is too thick, internal concentration polarization in the support layer is likely to occur, and there is a tendency to hinder separation by the semipermeable membrane. That is, when the composite hollow fiber membrane is used as a forward osmosis membrane or the like, the contact resistance between the driving solution and the supply solution increases, so that the permeability tends to decrease. Therefore, when the film thickness of the composite hollow fiber membrane is within the above range, the composite hollow fiber membrane has sufficient strength, is excellent in permeability, and can be preferably separated by a semipermeable membrane.

The composite hollow fiber membrane can be applied to a membrane separation technique using a semipermeable membrane. That is, the composite hollow fiber membrane can be used as, for example, an NF membrane, an RO membrane, an FO membrane, or the like. Among these, the composite hollow fiber membrane is preferably an FO membrane used in the FO method.

In the forward osmosis method, the composite hollow fiber membrane preferably has a high ratio of the water permeation rate in the dry state to the water permeation rate in the wet state. Specifically, this ratio is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. The higher this ratio is, the better, but basically, 100% is the upper limit excluding errors. That is, the ratio is preferably 40 to 100%, more preferably 50 to 100%, and even more preferably 60 to 100%. If the ratio is too low, the hydrophobicity of the composite hollow fiber membrane is relatively high, and the water permeability tends to be low in the forward osmosis method. It is considered that this is because at least one of the supply solution (FS) and the driving solution (DS) has a low affinity with the support layer and is difficult to penetrate into the semipermeable membrane layer. Further, from this, it is better not to dry the composite hollow fiber membrane when manufacturing or transporting the composite hollow fiber membrane module, that is, it is better to keep the composite hollow fiber membrane in a wet state, for example, the composite hollow fiber membrane. It is required to fill the hollow fiber membrane module with a liquid. Therefore, the transportation cost increases. As long as the ratio of the composite hollow fiber membrane provided in the composite hollow fiber membrane module is within the above range, the composite hollow fiber membrane module can be used in the forward osmosis method even in a dry state. When the composite hollow fiber membrane module is used by the forward osmosis method, the composite hollow fiber membrane is often used in a wet state. However, when the composite hollow fiber membrane module is transported to the composite hollow fiber membrane module without being filled with liquid, when the composite hollow fiber membrane module is started to be used in the forward osmosis method, the composite hollow fiber membrane is in a dry state. There may be. Even in such a case, the composite hollow fiber membrane module can be used in the forward osmosis method. From this, it is also possible to transport the liquid into the composite hollow fiber membrane module without filling it.

The ratio can be adjusted by various methods. For example, the support layer is hydrophilized so that the contact angle of water with respect to the outer peripheral surface of the support layer provided in the composite hollow fiber membrane module is 90 ° or less. There is a method of making it.

Examples of the water permeation rate in the wet state and the water permeation rate in the dry state in the forward osmosis method include the water permeation rate at 25 ° C.

Examples of the permeation rate of water in a dry state include a permeation rate measured by the following method. First, the composite hollow fiber membrane, which is the object to be measured, is dried. This drying is not particularly limited as long as the composite hollow fiber membrane can be dried, and examples thereof include drying in a blower constant temperature dryer at 60 ° C. for 24 hours or more. Using this dry composite hollow fiber membrane, the amount of water permeated through the composite hollow fiber membrane in 1 minute is measured by using a forward osmosis method. For example, an ion-exchanged water as a feed solution (FS) and a 0.6 M NaCl aqueous solution as a driving solution (DS) are placed on one side through a composite hollow fiber membrane, filtered, and composited. The amount of water permeated through the hollow fiber membrane in 1 minute is measured. The water permeation rate (L / m ² / hour: LMH) is obtained by converting the measured water permeation amount into a unit membrane area, a unit time, and a water permeation amount per unit pressure.

Examples of the permeation rate of water in a wet state include a permeation rate measured by the following method. First, the composite hollow fiber membrane, which is the object to be measured, is brought into a wet state. This wet state treatment (wet treatment) is not particularly limited as long as the composite hollow fiber membrane can be suitably wetted. Specifically, the composite hollow fiber membrane is immersed in a 50% by mass aqueous solution of ethanol for 20 minutes, and then washed with pure water for 20 minutes to perform a wetting treatment. The water permeation rate in the wet state is determined by the same method as the method for measuring the water permeation rate in the dry state, except that the hollow fiber membrane in the wet state is used instead of the hollow fiber membrane in the dry state. L / m ² / hour: LMH) is obtained.

In the forward osmosis method, the composite hollow fiber membrane preferably has a water permeation rate of 2 to 100 LMH, more preferably 3 to 100 LMH, and further preferably 3 to 80 LMH in a wet state. .. If the permeation rate is too low, the water permeation performance of the module tends to be insufficient when the composite hollow fiber membrane module is formed by using the composite hollow fiber membrane. On the other hand, if the permeation rate is too high, the separation by the semipermeable membrane layer becomes insufficient, and for example, the desalting performance tends to be insufficient.

(Manufacturing method of composite hollow fiber membrane)
The method for producing the composite hollow fiber membrane is not particularly limited as long as the above-mentioned composite hollow fiber membrane can be manufactured. Examples of the manufacturing method include the following manufacturing methods. The production method includes a step of contacting an aqueous solution of the polyfunctional amine compound (first contact step) with the outer peripheral surface (dense surface) side of the support layer, and a step of contacting the aqueous solution of the polyfunctional amine compound. A step of further contacting the organic solvent solution of the polyfunctional acid halide compound on the outer peripheral surface (dense surface) side of the support layer (second contact step), and an aqueous solution of the polyfunctional amine compound and the polyfunctional acid halide compound. A step (drying step) of drying the support layer to which the organic solvent solution is brought into contact is provided.

In the first contact step, an aqueous solution of the polyfunctional amine compound is brought into contact with the outer peripheral surface (dense surface) side of the support layer. By doing so, the aqueous solution of the polyfunctional amine compound permeates the support layer from the outer peripheral surface (dense surface) side.

The aqueous solution of the polyfunctional amine compound preferably has a concentration of the polyfunctional amine compound of 0.1 to 5% by mass, more preferably 0.1% by mass or more and less than 3% by mass. If the concentration of the polyfunctional amine compound is too low, a suitable semipermeable membrane layer tends not to be formed, such as pinholes being formed in the formed semipermeable membrane layer. Therefore, the separation by the semipermeable membrane layer tends to be insufficient. Further, if the concentration of the polyfunctional amine compound is too high, the semipermeable membrane layer tends to be too thick. If the semipermeable membrane layer becomes too thick, the permeability of the obtained composite hollow fiber membrane tends to decrease.

The aqueous solution of the polyfunctional amine compound is a solution in which the polyfunctional amine compound is dissolved in water, and additives such as salts, surfactants, and polymers may be added as needed.

In the second contact step, the organic solvent solution of the polyfunctional acid halide compound is further contacted with the outer peripheral surface (dense surface) side of the support layer to which the aqueous solution of the polyfunctional amine compound is in contact. By doing so, an interface between the aqueous solution of the polyfunctional amine compound and the organic solvent solution of the polyfunctional acid halide compound soaked into the support layer on the outer peripheral surface (dense surface) side is formed. Then, at the interface, the reaction between the polyfunctional amine compound and the polyfunctional acid halide compound proceeds. That is, interfacial polymerization of the polyfunctional amine compound and the polyfunctional acid halide compound occurs. A crosslinked polyamide is formed by this interfacial polymerization.

The organic solvent solution of the polyfunctional acid halide compound preferably has a concentration of the polyfunctional acid halide compound of 0.01 to 5% by mass, more preferably 0.01 to 3% by mass. If the concentration of the polyfunctional acid halide compound is too low, a suitable semipermeable membrane layer tends not to be formed, such as pinholes being formed in the formed semipermeable membrane layer. Therefore, the separation by the semipermeable membrane layer, for example, the desalting performance tends to be insufficient. Further, if the concentration of the polyfunctional acid halide compound is too high, the semipermeable membrane layer tends to be too thick. If the semipermeable membrane layer becomes too thick, the permeability of the obtained composite hollow fiber membrane tends to decrease.

The organic solvent solution of the polyfunctional acid halide compound is a solution in which the polyfunctional acid halide compound is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it is a solvent that dissolves the polyfunctional acid halide compound and does not dissolve in water. Examples of the organic solvent include alkane-based saturated hydrocarbons such as n-hexane, cyclohexane, heptane, octane, nonane, decane, and dodecane. As the organic solvent, the above-exemplified solvent may be used alone, or two or more kinds may be used in combination. Examples of the organic solvent include n-hexane and the like when used alone, and a mixed solvent of nonane, decane, and dodecane when used in combination of two or more. Additives such as salts, surfactants, and polymers may be added to the organic solvent, if necessary.

In the drying step, the support layer to which the aqueous solution of the polyfunctional amine compound and the organic solvent solution of the polyfunctional acid halide compound are brought into contact with each other is dried. In the second contact step, the crosslinked polyamide polymer obtained by interfacial polymerization by contacting the aqueous solution of the polyfunctional amine compound with the organic solvent solution of the polyfunctional acid halide compound is applied onto the dense surface of the support layer. It is formed to cover. By drying this support layer, the formed crosslinked polyamide polymer is dried, and a semipermeable membrane layer containing the crosslinked polyamide polymer is formed.

The temperature and the like of the drying are not particularly limited as long as the formed crosslinked polyamide polymer is dried. The drying temperature is, for example, preferably 50 to 150 ° C, preferably 80 to 130 ° C. If the drying temperature is too low, not only the drying tends to be insufficient, but also the drying time tends to be too long, and the production efficiency tends to decrease. Further, if the drying temperature is too high, the formed semipermeable membrane layer is thermally deteriorated, and it tends to be difficult to preferably perform separation by the semipermeable membrane. For example, desalting performance tends to decrease and water permeability tends to decrease. The drying time is preferably, for example, 1 to 30 minutes, and more preferably 1 to 20 minutes. If the drying time is too short, the drying tends to be insufficient. Further, if the drying time is too long, the production efficiency tends to decrease. In addition, the formed semipermeable membrane layer is thermally deteriorated, and it tends to be difficult to preferably perform separation by the semipermeable membrane. For example, desalting performance tends to decrease and water permeability tends to decrease.

According to the above-mentioned production method, separation by the semipermeable membrane layer can be preferably performed, and further, a composite hollow fiber membrane having excellent durability can be preferably produced.

(Case)
The housing is not particularly limited as long as it can be used as a housing for the hollow fiber membrane module. The inner diameter of the housing is preferably 10 to 200 cm, more preferably 10 to 100 cm, and even more preferably 10 to 50 cm. The height of the housing is preferably 0.3 to 3 m, more preferably 0.3 to 2 m, and even more preferably 0.5 to 1.5 m. If this housing is too large, it tends to be difficult to handle and the cost for maintenance tends to be high. Further, if the housing is too large, the residence time of the driving solution (DS) becomes long, so that the driving solution (DS) is diluted by the water permeated from the supply solution (FS), and the water permeability tends to deteriorate. is there. Further, if the housing is too small, it is not possible to secure a sufficient flow rate for practical use, and as a result, a large number of hollow fiber membrane modules are prepared, which increases the cost in terms of equipment and operation. Tend. The effective length of the composite hollow fiber membrane housed in the housing is preferably 0.3 to 3 m, more preferably 0.3 to 2 m, and 0.5 to 1.5 m. Is even more preferable.

In the composite hollow fiber membrane module, the filling rate of the composite hollow fiber membrane is preferably 10 to 65%, more preferably 10 to 60%, and further preferably 20 to 55%. If the filling rate is too low, the water permeability of the composite hollow fiber membrane module tends to be insufficient. On the other hand, if the filling rate is too high, it tends to be difficult to maintain the excellent water permeability of the composite hollow fiber membrane module for a long period of time. It is considered that this is because the contact between the composite hollow fiber membranes increases during the operation, so that the semipermeable membrane layer provided on the outer peripheral surface side of the composite hollow fiber membrane is damaged. Therefore, when the filling rate is within the above range, the water permeability of the composite hollow fiber membrane module is excellent, and this excellent water permeability can be maintained for a long period of time.

The filling rate of the composite hollow fiber membrane is the ratio of the total cross-sectional area of the plurality of composite hollow fiber membranes to the area of the cross section inside the housing perpendicular to the longitudinal direction (fiber direction) of the composite hollow fiber membrane. Specifically, as shown in FIG. 4, the sum of the plurality of composite hollow fiber membranes 11 with respect to the cross-sectional area of the hollow portion of the housing 2 perpendicular to the longitudinal direction (fiber direction) of the composite hollow fiber membrane 11. The ratio of cross-sectional areas. The cross-sectional area of the composite hollow fiber membrane 11 is not only the cross-sectional area of the hollow portion but also the cross-sectional area including the film itself, and is a cross-sectional area calculated from the outer diameter of the composite hollow fiber membrane 11. Then, the calculation method of the filling rate is, for example, the number (lines) of the composite hollow fiber membranes housed in the housing 2 and the cross-sectional area (m ² / line) of one of the composite hollow fiber membranes 11. , That is, the area occupied by the hollow fiber membrane 11 in the housing 2, is divided by the area calculated from the inner diameter of the housing 2, that is, the inner area of the housing 2. The filling rate can be calculated. Note that FIG. 4 is a schematic cross-sectional view of the hollow fiber membrane module shown in FIG.

The composite hollow fiber membrane module preferably has a withstand voltage of 0.1 to 3 MPa, more preferably 0.1 to 2.5 MPa, and even more preferably 0.1 to 2.3 MPa. .. This pressure resistance is the maximum pressure at which operation can be maintained when pressure is applied from the outside or the inside of the composite hollow fiber membrane module. For example, the maximum pressure that can maintain the shape of the composite hollow fiber membrane when pressure is applied from the outside of the composite hollow fiber membrane and the maximum that can maintain the shape of the composite hollow fiber membrane when pressure is applied from the inside of the composite hollow fiber membrane. The lower of the pressures. The maximum pressure at which the shape of the composite hollow fiber membrane can be maintained when pressure is applied from the outside of the composite hollow fiber membrane is, for example, the pressure is applied from the outside of the composite hollow fiber membrane and the composite hollow fiber membrane is crushed. It is the pressure at the time. The maximum pressure that can maintain the shape of the composite hollow fiber membrane when pressure is applied from the inside of the composite hollow fiber membrane is, for example, the pressure is applied from the inside of the composite hollow fiber membrane and the composite hollow fiber membrane bursts. It is the pressure when it is done. If the pressure resistance is too low, the housing or the composite hollow fiber membrane provided in the composite hollow fiber membrane module tends to be easily damaged when the supply solution (FS) and the driving solution (DS) are circulated. A pressure resistance that is too high may not be necessary in practice. Further, if the pressure resistance is too high, not only the cost increases in order to satisfy the excessive pressure resistance, but also the pressure resistance tends to be given too much priority and the water permeability tends to decrease.

The composite hollow fiber membrane module can be applied to a membrane separation technique using a semipermeable membrane. That is, the composite hollow fiber membrane module can be used, for example, in the NF method, the RO method, the FO method, and the like. Among these, the composite hollow fiber membrane module is preferably used in the FO method. Examples of the supply solution (FS) and the driving solution (DS) when the composite hollow fiber membrane module is used in the FO method include the following solutions.

The feed solution (FS) is not particularly limited as long as it is a feed solution used in the forward osmosis method. Specific examples of the feed solution (FS) include a dilute solution having an osmotic pressure lower than that of the driving solution (DS). More specifically, a solution in which salts such as water, sodium chloride, ammonium carbonate, and calcium carbonate are dissolved, a solution in which sugars such as sucrose and dextrose are dissolved, and a polymer compound such as polypropylene glycol and polyethylene glycol. Examples thereof include a solution prepared by dissolving the above. From a more practical point of view, the feed solution (FS) includes, for example, seawater, industrial wastewater, sewer water, liquid as food, etc., and these can be used as the feed solution (FS) to draw out water. Conceivable.

The driving solution (DS) is not particularly limited as long as it is a driving solution used in the forward osmosis method. Specific examples of the driving solution (DS) include a concentrated solution having an osmotic pressure higher than that of the supply solution (FS). More specifically, the driving solution (DS) includes a solution in which salts such as sodium chloride, ammonium carbonate, and calcium carbonate are dissolved, a solution in which sugars such as sucrose and dextrose are dissolved, and polypropylene glycol and polyethylene glycol. Examples thereof include a solution in which a polymer compound such as the above is dissolved, a dispersed liquid having magnetism, and an ionic liquid. Among these, the driving solution (DS) used for the composite hollow fiber membrane module according to the present embodiment is highly hydrophilic (highly compatible with water) and is compatible with water by some external stimulus. It is preferable that the material has a property of reducing and separating. Specific examples of the external stimulus include temperature, pH, magnetic force, and light. Among these, a driving solution having a change in compatibility with water depending on the temperature is preferable.

As described above, the composite hollow fiber membrane module can be used in the forward osmosis method, and specifically, can be used in a water treatment method, an energy production method, and the like.

The water-making method includes, for example, a step of drawing water from the supply solution to the driving solution using the driving solution, and a step of separating / regenerating the driving solution and the drawn water. From these steps, water is obtained by separating the water drawn from the supply solution into the driving solution from the driving solution. Further, at that time, by using a driving solution whose compatibility with water is reduced by an external stimulus as described above, the water can be easily separated in the separation / regeneration step. Further, by using a driving solution whose compatibility with water decreases depending on the temperature as the driving solution, the separation of water in the separation / regeneration step becomes easier.

Examples of the energy production method include a step of drawing water from the supply solution to the driving solution in a space in which the driving solution is pressurized, and increasing the volume of the driving solution by the drawn water on the driving solution side. It includes a step of rotating a turbine according to a minute to extract energy.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited thereto.

[Example 1]
(Preparation of composite hollow fiber membrane)
As the support layer of the composite hollow fiber membrane, the hollow fiber membrane provided in the external pressure type hollow fiber membrane module (Pureia GS manufactured by Kuraray Co., Ltd.) was used.

The contact angle of water with respect to the outer peripheral surface of this support layer was measured as follows.

Water droplets were dropped on the outer peripheral surface of the support layer, and an image at that moment was taken. Then, the angle formed by the water droplet surface and the outer peripheral surface was measured at the place where the water droplet surface was in contact with the outer peripheral surface. This angle is the contact angle of water. As a measuring device, a Drop Master 700 manufactured by Kyowa Interface Science Co., Ltd. was used. The contact angle of water with respect to the outer peripheral surface obtained by the above measurement method was 45 °.

A semipermeable membrane layer was formed on the outer surface side of the support layer.

Specifically, the support layer was first immersed in a 50% by mass aqueous solution of ethanol for 20 minutes, and then immersed in pure water for 30 minutes to perform a wetting treatment. The wet support layer subjected to this wet treatment was fixed to the frame so as not to come into contact with other support layers. Then, this support layer is immersed in a 2% by mass aqueous solution of m-phenylenediamine so that the 2% by mass aqueous solution of m-phenylenediamine, which is an aromatic polyfunctional amine compound, comes into contact with the outer peripheral surface side of the support layer for 2 minutes. I let you. By doing so, a 2% by mass aqueous solution of m-phenylenediamine was impregnated from the outer peripheral surface side of the support layer. Then, the excess 2% by mass aqueous solution of m-phenylenediamine that did not soak into the support layer was removed.

Then, 0.2 mass% hexane of trimesic acid trichloride is applied to this support layer so that a 0.2 mass% hexane solution of trimesic acid trichloride, which is an aromatic acid halide compound, comes into contact with the outer peripheral surface side of the support layer. It was immersed in the solution for 1 minute. By doing so, an interface is formed between the m-phenylenediamine aqueous solution soaked into the outer peripheral surface side of the support layer and the hexane solution of trimesic acid trichloride. Then, at this interface, interfacial polymerization of m-phenylenediamine and trimesic acid trichloride proceeds to form a crosslinked polyamide.

Then, the support layer formed by the crosslinked polyamide was dried in a dryer at 90 ° C. for 10 minutes. By doing so, a semipermeable membrane layer was formed on the outer peripheral surface side of the support layer so as to come into contact with the outer peripheral surface. It was also found from the observation with a scanning electron microscope that this semipermeable membrane layer was formed. Specifically, the outer surface of the composite hollow fiber membrane in which the semipermeable membrane layer was formed on the support layer was observed using a scanning electron microscope (S-3000N manufactured by Hitachi, Ltd.). From this obtained image, it was found that the semipermeable membrane layer was preferably formed on the outer surface side of the composite hollow fiber membrane. The formed semipermeable membrane layer had a thickness of 300 nm. The thickness of the support layer was 0.2 mm.

(Composite hollow fiber membrane)
By the above manufacturing method, a composite hollow fiber membrane having a support layer and a semipermeable membrane layer was obtained. This composite hollow fiber membrane had an outer diameter of 1.0 mm, an inner diameter of 0.6 mm, and a film thickness of 0.2 mm. The film thickness of the composite hollow fiber membrane and the film thickness of the support layer are almost the same. This is because the semipermeable membrane layer is very thin as compared with the support layer, so that the thickness is within the error range.

[Evaluation]
The composite hollow fiber membrane obtained as described above was evaluated by the method shown below.

(Water permeability of the composite hollow fiber membrane in the dry state: Water permeation rate in the dry state)
The obtained composite hollow fiber membrane was dried in a warm air dryer at 60 ° C. for 24 hours to completely dry the moisture inside the composite hollow fiber membrane.

Then, this dry composite hollow fiber membrane was used in the forward osmosis (FO) method to measure the permeation rate of water. Specifically, a 0.6 M NaCl aqueous solution as a simulated driving solution (simulated DS) and ion-exchanged water as a simulated supply solution (simulated FS) are mixed through the obtained dry composite hollow fiber membrane. Placed and filtered. At that time, the simulated DS was flowed on the semipermeable membrane side of the composite hollow fiber membrane, and the simulated FS was flowed on the support layer side of the composite hollow fiber membrane. The amount of water permeated from the simulated FS to the simulated DS was calculated from the weight changes of the simulated FS and the simulated DS. Then, the water permeation rate (JwFOdry) (L / m ² / hour: LMH) was obtained by converting the calculated water permeation amount into the unit membrane area, the unit time, and the water permeation amount per unit pressure. This permeation rate was evaluated as the water permeability of the dry composite hollow fiber membrane.

(Water permeability of composite hollow fiber membrane in wet state: Permeation rate of pure water in wet state)
The obtained composite hollow fiber membrane was immersed in a 50% by mass aqueous solution of ethanol for 1 minute, and then immersed in pure water for 30 minutes. Using this swollen composite hollow fiber membrane in the forward osmosis (FO) method, the permeation rate of pure water in the wet state (JwFOet) (L / m) is the same as the permeation rate of water in the dry state. ² / hour: LMH) was measured. This permeation rate was evaluated as the water permeability of the wet composite hollow fiber membrane.

(Ratio of water permeation rate in dry state to water permeation rate in wet state in composite hollow fiber membrane: water permeation rate in dry state / water permeation rate in wet state)
By dividing the water permeation rate in the dry state calculated as described above by the water permeation rate in the wet state, the permeation rate of water in the dry state is relative to the permeation rate of water in the wet state. The rate ratio (water permeation rate in the dry state / water permeation rate in the wet state: JwFOdry / JwFOwet) was calculated.

(Manufacturing of composite hollow fiber membrane module)
Using the composite hollow fiber membrane, the composite hollow fiber membrane module shown in FIG. 1 was produced. The composite hollow fiber membrane provided in the composite hollow fiber membrane module has hollow portions at the upper end and the lower end opened, and both the upper portion and the lower portion are sealed with an epoxy resin except for the hollow fiber opening portion. .. The hollow fiber membrane had an effective length of 1 m. The inner diameter of the hollow fiber membrane module housing was 20 cm. Then, this hollow fiber membrane was housed in the housing of the hollow fiber membrane module so that the filling rate was 40%.

[Evaluation]
(Pressure strength of composite hollow fiber membrane module)
Water was alternately added to the bore side and the shear side of the obtained composite hollow fiber membrane module so that the pressure inside the housing increased by 0.1 MPa, and the water was added to the housing of the composite hollow fiber membrane module. This continued until water leaked due to breakage or water leak between the shell and bore due to breakage of the composite hollow fiber membrane. The pressure immediately before the occurrence of these water leaks was defined as the pressure resistance strength of the composite hollow fiber membrane module.

(Water permeability of composite hollow fiber membrane module in dry state: Water permeation rate in dry state)
The obtained composite hollow fiber membrane module was dried in a warm air dryer at 60 ° C. for 24 hours to completely dry the moisture inside the composite hollow fiber membrane.

Then, this dry composite hollow fiber membrane module was used in the forward osmosis (FO) method to measure the permeation rate of water. Specifically, a 0.6 M NaCl aqueous solution as a simulated driving solution (simulated DS) and ion-exchanged water as a simulated supply solution (simulated FS) are mixed through the obtained dry composite hollow fiber membrane. Placed and filtered. At that time, the simulated DS was flowed on the share side of the composite hollow fiber membrane module, and the simulated FS was flowed on the bore side of the composite hollow fiber membrane module. The amount of water permeated from the simulated FS to the simulated DS was calculated from the weight changes of the simulated FS and the simulated DS. Then, the water permeation rate (JwmodFOdry) (L / m ² / hour: LMH) was obtained by converting the calculated water permeation amount into the unit membrane area, the unit time, and the water permeation amount per unit pressure. This permeation rate was evaluated as the water permeability of the dry composite hollow fiber membrane module.

(Water permeability of composite hollow fiber membrane module in wet state: Permeability rate of pure water in wet state)
The obtained composite hollow fiber membrane was immersed in a 50% by mass aqueous solution of ethanol for 1 minute, and then immersed in pure water for 30 minutes. Using this swollen composite hollow fiber membrane in the forward osmosis (FO) method, the permeation rate of pure water in the wet state (JwmodFOet) (L / m) by the same method as the permeation rate of water in the dry state. ² / hour: LMH) was measured. This permeation rate was evaluated as the water permeability of the wet composite hollow fiber membrane module.

(Ratio of water permeation rate in dry state to water permeation rate in wet state in composite hollow fiber membrane module: water permeation rate in dry state / water permeation rate in wet state)
By dividing the water permeation rate in the dry state calculated as described above by the water permeation rate in the wet state, the permeation rate of water in the dry state is relative to the permeation rate of water in the wet state. The ratio of the velocities (water permeation rate in the dry state / water permeation rate in the wet state: JwmodFOdry / JwmodFOwet) was calculated.

The evaluation results and the like are shown in Table 1.

[Example 2]
As a support layer for the composite hollow fiber membrane, instead of the hollow fiber membrane provided in the external pressure type hollow fiber membrane module (Pureia GS manufactured by Kuraray Co., Ltd.), the external pressure type hollow fiber membrane module (Pureia GL manufactured by Kuraray Co., Ltd.) A composite hollow fiber membrane module was obtained in the same manner as in Example 1 except that the hollow fiber membrane provided in) was used.

The contact angle of water with respect to the outer peripheral surface of this support layer was 45 °. Further, the formed semipermeable membrane layer had a thickness of 280 nm. The thickness of the support layer was 0.25 mm. The obtained composite hollow fiber membrane had an outer diameter of 1.25 mm, an inner diameter of 0.75 mm, and a film thickness of 0.25 mm. The film thickness of the composite hollow fiber membrane and the film thickness of the support layer are almost the same. This is because the semipermeable membrane layer is very thin as compared with the support layer, so that the thickness is within the error range.

The evaluation results and the like are shown in Table 1.

[Example 3]
A composite hollow fiber membrane module was obtained in the same manner as in Example 1 except that the inner diameter of the housing of the composite hollow fiber module was 28 cm, the effective length of the composite hollow fiber membrane was 0.6 m, and the filling rate was 25%. ..

The evaluation results and the like are shown in Table 1.

[Example 4]
A composite hollow fiber membrane module was obtained in the same manner as in Example 1 except that the inner diameter of the housing of the composite hollow fiber module was 18 cm, the effective length of the composite hollow fiber membrane was 1.8 m, and the filling rate was 49%. ..

The evaluation results and the like are shown in Table 1.

[Comparative Example 1]
A composite hollow fiber membrane module was obtained in the same manner as in Example 1 except that a composite hollow fiber membrane in which the surface on which the semipermeable membrane layer was formed was changed from the outer surface of the support layer to the inner surface of the support layer.

The evaluation results and the like are shown in Table 1.

[Comparative Example 2]
A composite hollow fiber membrane module was obtained in the same manner as in Example 1 except that the inner diameter of the composite hollow fiber module was 9 cm and the effective length of the composite hollow fiber membrane was 3.3 m.

The evaluation results and the like are shown in Table 1.

From Table 1, a composite hollow fiber membrane provided with a semipermeable membrane layer containing a crosslinked polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound so as to contact the outer peripheral surface of a hollow fiber-like porous support layer is provided. In the case of a composite hollow fiber membrane module housed in a housing having an inner diameter of 10 to 200 cm so that the effective length is 0.3 to 3 m (Examples 1 to 4), other than such a composite hollow fiber membrane module. In the case of (Comparative Examples 1 and 2), the permeation rate of water in the wet state as a module was high. Further, since the ratio of the permeation rate of water in the dry state to the permeation rate of water in the swollen state as a module was not particularly low as compared with Comparative Examples 1 and 2, water in the dry state as a module. It was found that the permeation speed of was also high. That is, it was found that the composite hollow fiber membrane modules according to Examples 1 to 4 can maintain a high water permeability (water permeability) even in a dry state.

From the above, it was found that the composite hollow fiber membrane module according to Examples 1 to 4 is a composite hollow fiber membrane module having excellent water permeability.

On the other hand, when a composite hollow fiber membrane provided with a semipermeable membrane layer in contact with the inner peripheral surface of the support layer is used (Comparative Example 1), the permeation rate of water in a wet state as a module is sufficiently high. I couldn't raise it.

Further, when a thin housing having an inner diameter of 10 cm or less is used, even if the effective length of the composite hollow fiber membrane is increased to 3.3 m and the filling rate is 40% (Comparative Example 2), the wet state as a module is obtained. The permeation rate of water in the water could not be sufficiently increased.

1 Composite hollow fiber membrane module 2 Housing 4 Lower end sealant 5 Upper end sealant 6 Shell side inlet 7 Shell side outlet 8 Bore side inlet 9 Bore side outlet 11 Composite hollow fiber membrane 12 Support layer 13 Semipermeable membrane layer

Claims (8)

A housing and a plurality of composite hollow fiber membranes housed in the housing are provided.
The composite hollow fiber membrane
A semipermeable membrane layer containing a crosslinked polyamide composed of a polyfunctional amine compound and a polyfunctional acid halide compound, and a hollow filament-like porous support layer are provided.
The semipermeable membrane layer is in contact with the outer peripheral surface of the support layer.
The inner diameter of the housing is 10 to 200 cm.
A composite hollow fiber membrane module characterized in that the effective length of the composite hollow fiber membrane is 0.3 to 3 m. The composite hollow fiber membrane module according to claim 1, wherein the composite hollow fiber membrane has an outer diameter of 0.1 to 2 mm and an inner diameter of 0.05 to 1.5 mm. Claim 1 or claim that the ratio of the total cross-sectional area of the plurality of composite hollow fiber membranes to the area of the cross section perpendicular to the longitudinal direction of the composite hollow fiber membrane inside the housing is 10 to 65%. 2. The composite hollow fiber membrane module according to 2. The composite hollow fiber membrane module according to any one of claims 1 to 3 used in the forward osmosis method. The composite hollow fiber membrane according to claim 4, wherein the ratio of the water permeation rate in the dry state to the water permeation rate in the wet state is 40 to 100% in the forward osmosis method. module. The composite hollow fiber membrane module according to claim 4 or 5, wherein the composite hollow fiber membrane has a water permeation rate of 2 to 100 LMH in a wet state in a forward osmosis method. The composite hollow fiber membrane module according to any one of claims 1 to 6, wherein the contact angle of water with respect to the outer peripheral surface of the support layer is 90 ° or less. The composite hollow fiber membrane module according to any one of claims 1 to 7, wherein the pressure resistance is 0.1 to 3 MPa.