Composite semipermeable membrane

Abstract

The present invention provides a composite semipermeable membrane having a high desalination performance and a more excellent water permeability. The composite semipermeable membrane (1) comprises a porous supporting layer (10) and a separation functional layer (20) containing aromatic polyamide formed on the porous supporting layer (10), wherein the separation functional layer (20) has a plurality of hollow cells (21), and in cross-sectional observation at a magnification of 8000 times using a transmission electron microscope, the cross-sectional area is 1000 nm. 2 ~8000nm 2 The total value of each area of ​​the unit (21) in two different regions of 2.8 μm × 2.8 μm is 1.8 × 10 5 nm 2 ~1.0×10 7 nm 2 .

Description

Technical Field

[0001] The present disclosure relates to composite semipermeable membranes. Background Art

[0002] In the past, composite semipermeable membranes have been used for purification of tap water, desalination of seawater or salt water, production of industrial ultrapure water, etc. As a document recording such technology, there is, for example, Patent Document 1. Patent Document 1 records a composite separation membrane having a separation function layer, wherein the separation function layer is a polyamide layer having a first layer portion and a second layer portion, wherein the first layer portion has a plurality of protrusions, and the second layer portion covers at least a portion of the plurality of protrusions.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-189340 Summary of the invention

[0006] However, in a purification system for purifying tap water, a composite semipermeable membrane having high desalination and high water permeability is required. The water permeability of existing composite semipermeable membranes is low, so a pressure pump is sometimes provided in the purification system. Although the composite separation membrane of Patent Document 1 has excellent desalination and water permeability, there is still room for further improvement in terms of improving the water permeability under low pressure conditions.

[0007] The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a composite semipermeable membrane having a more excellent water permeability while maintaining a high desalination performance.

[0008] The present disclosure relates to a composite semipermeable membrane, comprising a porous supporting layer and a separation functional layer containing aromatic polyamide formed on the porous supporting layer, wherein the separation functional layer has a plurality of hollow cells and, in cross-sectional observation at a magnification of 8000 times using a transmission electron microscope, the cross-sectional area is 1000 nm. 2 ~8000nm 2 The total value of each area of ​​the above-mentioned unit in two different regions of 2.8 μm×2.8 μm is 1.8×10 5 nm 2 ~1.0×10 7 nm 2 .

[0009] In addition, the present disclosure relates to a composite semipermeable membrane comprising a porous supporting layer and a separation functional layer containing aromatic polyamide formed on the porous supporting layer, wherein the separation functional layer has a plurality of hollow cells and, in cross-sectional observation at a magnification of 8000 times using a transmission electron microscope, the cross-sectional area is 1000 nm. 2~8000nm 2 The above-mentioned units include 60 to 3500 in total in two different regions of 2.8 μm×2.8 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a diagram showing a membrane element including a composite semipermeable membrane according to one embodiment of the present disclosure.

[0011] Figure 2 It is a figure which shows the composite semipermeable membrane which concerns on one Embodiment of this disclosure.

[0012] Figure 3 It is a diagram showing a method for producing a composite semipermeable membrane according to one embodiment of the present disclosure.

[0013] Figure 4 It is a diagram showing the cross-sectional area of ​​the accumulated cells of Example 1, Example 2, and Comparative Example 1 of the present disclosure.

[0014] Figure 5 It is a graph showing the distribution of the cross-sectional area of ​​the cells in Example 1, Example 2, and Comparative Example 1 of the present disclosure.

[0015] Figure 6 It is a graph showing the distribution of the cross-sectional area of ​​the cells in Example 1, Example 2, and Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments.

[0017] The composite semipermeable membrane 1 according to this embodiment is a membrane for removing impurities such as salts from water to be treated. The composite semipermeable membrane 1 is used in a membrane element 2 of a purification device for purifying water to be treated such as tap water. The membrane element 2 is filled in a pressure vessel of the purification device.

[0018] [Membrane element]

[0019] like Figure 1 As shown, the membrane element 2 includes a water collecting tube 3, a composite semipermeable membrane 1, and a mesh-like spacer 4. The membrane element 2 is formed by spirally winding the composite semipermeable membrane 1 sandwiched between two spacers 4 around the water collecting tube 3.

[0020] The treated water supplied from one end of the membrane element 2 is supplied to the composite semipermeable membrane 1 through the flow path formed by the spacer 4. Figure 1 As shown, part of the treated water passes through the composite semipermeable membrane 1, collects in the water collecting pipe 3, and is recovered as permeated water from the other end of the membrane element 2. The treated water that does not pass through the composite semipermeable membrane 1 is discharged from the other end of the membrane element 2 as waste water.

[0021] [Composite semipermeable membrane]

[0022] Next, refer to Figure 2 The composite semipermeable membrane 1 according to the present embodiment will be described. The composite semipermeable membrane 1 includes a porous supporting layer 10 and a separation functional layer 20 .

[0023] The porous supporting layer 10 includes a substrate 11 and a porous support body 12 formed on the substrate 11 .

[0024] The substrate 11 is a sheet-like member such as a nonwoven fabric. For example, the material of the nonwoven fabric includes polyethylene, polyester, etc. The thickness of the substrate 11 is preferably 30 μm to 120 μm. In the present embodiment, the thickness of the substrate 11 is about 90 μm.

[0025] The porous support 12 is a film having a pore structure. The size of the pores of the porous support 12 is not particularly limited, but is, for example, preferably 300 nm or less, and more preferably 30 nm or less.

[0026] The thickness of the porous support 12 is preferably 20 μm to 100 μm. In the present embodiment, the thickness of the porous support 12 is approximately 50 μm.

[0027] Examples of the material of the porous support 12 include polysulfone, polyethersulfone, cellulose acetate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, polyphenylene sulfide sulfone, polyimide, and polyvinylidene fluoride. Among them, polysulfone is particularly preferred because of its high chemical stability, mechanical stability, and thermal stability.

[0028] The separation functional layer 20 is a layer having a plurality of hollow cells 21 formed on the porous support layer 10. The separation functional layer 20 is mainly composed of aromatic polyamide. Aromatic polyamide can be synthesized, for example, by an interfacial polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional halogen oxide.

[0029] As the polyfunctional aromatic amine, at least one polyfunctional aromatic amine selected from meta-phenylenediamine (MPD), para-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,4-diaminoanisole, amphenol, xylylenediamine, N-methyl-meta-phenylenediamine and N-methyl-para-phenylenediamine is preferred, and these may be used alone or in combination of two or more.

[0030] Examples of the polyfunctional acid halide include trimesoyl chloride (TMC), 1,3,5-cyclohexanetricarboxylic acid chloride, and 1,2,4-cyclobutanetricarboxylic acid chloride. Examples of the difunctional acid halide include biphenyl dicarboxylic acid chloride, terephthaloyl chloride, naphthalene dicarboxylic acid chloride, and cyclohexane dicarboxylic acid chloride.

[0031] In addition to aromatic polyamide, the separation functional layer 20 may also contain cellulose nanofibers (CNF). The CNF content of the separation functional layer 20 is preferably 0.001% to 1% by mass relative to the aromatic polyamide, more preferably 0.03% to 0.5% by mass, and further preferably 0.05% to 0.35% by mass. By using the separation functional layer 20 containing 0.05% to 0.35% by mass of CNF relative to the aromatic polyamide, the chlorine resistance and fouling resistance of the composite semipermeable membrane 1 are further improved. The CNF content (C) is obtained by using the FTIR data of the membrane surface, from 1237 cm -1 Nearby (P1) and 1486cm -1 It was determined from the ratio of the peak intensities near (P2) (R = P1 / P2) and the formula C = 5.3-5.34R.

[0032] The separation function layer 20 has a plurality of hollow cells 21. Figure 1 As shown, a corrugated structure with continuous and repeated concavities and convexities can be formed by overlapping a plurality of units 21 in the thickness direction of the separation functional layer 20. The thickness of the separation functional layer 20 is preferably 100 nm to 2000 nm, more preferably 500 nm to 1000 nm.

[0033] The cell 21 of this embodiment has a cross-sectional area of ​​1000 nm in cross-sectional observation using a transmission electron microscope (TEM). 2 ~8000nm 2 The unit 21 includes 60 to 3500 units in two different regions of 2.8 μm×2.8 μm. In addition, the cross-sectional area is 1000 nm. 2 ~8000nm 2 The total value of each area of ​​the unit 21 in two different regions of 2.8 μm×2.8 μm is 1.8×10 5 nm 2 ~1.0×10 7 nm 2 It should be noted that the “cross-sectional area of ​​the unit 21 ” mentioned in this specification refers to the cross-sectional area of ​​each hollow portion formed in the separation functional layer 20 .

[0034] As the treated water passes through the separation functional layer 20, impurities such as salts contained in the treated water are removed. When there are a large number of cells 21 with a small unit cross-sectional area in the separation functional layer 20, the treated water passes through a large number of cells 21, so that although the desalination performance is improved, the water permeability is reduced. On the other hand, when there are a large number of cells 21 with a large unit cross-sectional area, since the treated water does not pass through a sufficient number of cells 21, although the water permeability is improved, the desalination performance is reduced.

[0035] In this embodiment, high desalination performance and water permeability are achieved by adjusting the cross-sectional area and number of the units 21 included in the separation functional layer 20. Specifically, in cross-sectional observation using TEM, the following structure is obtained: the cross-sectional area is 1000 nm 2 ~8000nm 2 The units 21 of the separation function layer 20 include 60 to 3500 in total in two different regions of 2.8 μm×2.8 μm. In addition, the following configuration is adopted: the cross-sectional area is 1000 nm 2 ~8000nm 2 The total value of each area of ​​the unit 21 in two different regions of 2.8 μm×2.8 μm is 1.8×10 5 nm 2 ~1.0×10 7 nm 2 With this structure, the composite semipermeable membrane 1 has high desalination and high water permeability under low pressure conditions. In order to achieve higher desalination and water permeability, it is preferred to have the following structure: the cross-sectional area is 1000nm 2 ~8000nm 2 The number of the units 21 is 70 to 1750 in total in two different regions of 2.8 μm×2.8 μm in the separation function layer 20. In addition, it is preferable to have the following configuration: the cross-sectional area is 1000 nm 2 ~8000nm 2 The total area of ​​each unit 21 in the two different regions of 2.8 μm×2.8 μm in the separation functional layer 20 is 2.0×10 5 nm 2 ~5.0×10 6 nm 2 .

[0036] [Measurement method of separation functional layer using TEM]

[0037] Next, a method for measuring the separation functional layer 20 using TEM will be described in detail.

[0038] First, the composite semipermeable membrane 1 was cut in the thickness direction by cryo-ultra-thin sectioning to obtain a thin slice. It should be noted that the thin slice was cut with an ultra-thin slicer (manufactured by Leica Microsystems) at a thickness of 40 nm to 45 nm. Then, the obtained thin slice of the composite semipermeable membrane 1 was subjected to carbon deposition to prepare a sample for TEM observation.

[0039] Next, the sample of the prepared separation function layer 20 is measured by TEM and an image is taken. As TEM, for example, a transmission electron microscope (HT-7700, manufactured by Hitachi High-Tech Corporation) can be used. The measurement conditions of TEM are appropriately determined according to the measurement object. For example, the following conditions can be selected.

[0040] Resolution: 0.204nm

[0041] Accelerating voltage: 100 kV

[0042] Magnification: 8000 times

[0043] It should be noted that the magnification mentioned here refers to the magnification set on the transmission electron microscope device (the same applies hereinafter).

[0044] Next, WinROOF (manufactured by Mitani Shoji Co., Ltd.) was used to analyze the image obtained by the measurement using TEM. Then, the analysis range of the image was set to an area of ​​2.8 μm×2.8 μm, and the specified parameters were measured. At this time, the specified parameters were measured in a state where the extension direction of the separation function layer 20 in the image was roughly parallel to at least one of the four sides that determined the analysis range, and at least from the interface between the porous support layer 10 and the separation function layer 20 to the outermost surface of the separation function layer 20 was included in the analysis range. Then, the specified parameters of two different areas were measured, and their total value was evaluated.

[0045] As parameters, the cross-sectional area of ​​each unit 21 included in the separation functional layer 20, the total number of units 21, the sum of the cross-sectional areas of the units 21, etc. are listed. When measuring the cross-sectional area of ​​each unit 21, the total number of units 21, and the sum of the cross-sectional areas of the units 21, the cross-sectional area less than 100 nm is used. 2 Unit 21 and greater than 10000nm 2 The unit 21 is deleted from the measurement data.

[0046] [Method for producing composite semipermeable membrane]

[0047] Next, use Figure 3 The manufacturing method of the composite semipermeable membrane 1 of the present disclosure is described. In the following description, an example of a manufacturing method of the composite semipermeable membrane 1 using a polyethylene nonwoven fabric as the substrate 11, using polysulfone as the raw material of the porous support 12, and using an MPD solution containing a multifunctional aromatic amine MPD as the raw material of the aromatic polyamide is described. The manufacturing method involved in this embodiment includes a porous support layer preparation step, an impregnation step, a polymerization step, and a post-treatment step.

[0048] First, in the porous supporting layer preparation step, polysulfone is applied to the surface of a polyethylene nonwoven fabric to prepare a porous supporting layer 10 including a porous supporting body 12 having a thickness of about 50 μm.

[0049] Next, in the impregnation process, the MPD solution containing a specified amount of a polyfunctional aromatic amine and an additive is impregnated in the porous support 12 of polysulfone. The MPD solution is an aqueous solution containing distilled water as a solvent, 0.5% to 2.0% by mass of MPD, 0.15% by mass of sodium lauryl sulfate (SLS), 0.5% to 2.0% by mass of triethylamine (TEA), 1.0% to 4.0% by mass of camphorsulfonic acid (CSA), and 6.0% to 15% by mass of isopropyl alcohol (IPA) as an additive. As additives other than IPA, CNF can be cited. In the impregnation process, the MPD solution is impregnated in the skin layer of the porous support 12 and left for 1 second to 60 seconds. Then, the MPD solution excessively applied on the surface of the porous support 12 is removed, and the droplets of the MPD solution are removed from the surface using an air knife or a scraper, and left for 10 seconds to 60 seconds.

[0050] Next, in the polymerization step, the surface of the porous support 12 coated with the MPD solution is impregnated with a polyfunctional acid halide solution and left for 120 seconds to promote the interfacial polycondensation reaction. As the polyfunctional acid halide solution, for example, a TMC solution prepared by dissolving TMC and an appropriate amount of an amphiphilic solvent such as ethyl acetate in an isoparaffin hydrocarbon to a TMC concentration of 0.05 mass % to 0.1 mass % can be cited.

[0051] Finally, in the post-treatment step, the TMC solution was removed, the mixture was dried in a drying oven at 120° C. for 3 minutes, and then washed in water, thereby forming a composite semipermeable membrane 1 having a separation functional layer 20 .

[0052] Example

[0053] Next, embodiments of the present disclosure are described. The present disclosure is not limited to these embodiments.

[0054] [Method for producing composite semipermeable membrane]

[0055] <Example 1>

[0056] In Example 1, a layer of a porous support 12 having a thickness of about 50 nm formed on a polyethylene nonwoven fabric is used as the porous support layer 10. First, an MPD solution is injected into the surface of the porous support 12 surrounding the four sides of the polysulfone and left for 10 seconds. As the MPD solution, a solution containing 0.8% by mass of MPD, 0.15% by mass of SLS, 0.8% by mass of TEA, 1.6% by mass of CSA and 10% by mass of IPA in distilled water as a solvent is used. Thereafter, the MPD aqueous solution excessively coated on the surface of the porous support 12 is removed, and the MPD solution attached to the membrane is removed with a scraper, and left for 60 seconds. Then, a TMC solution is injected into the surface of the porous support 12 coated with the MPD solution and left for 120 seconds. As the TMC solution, a solution in which 0.1% by mass of TMC and 2% by mass of ethyl acetate are dissolved in IP Solvent 1016 as an isoparaffin hydrocarbon is used. Thereafter, the TMC solution was removed and the film was dried in a drying oven at 120° C. for 3 minutes. Thereafter, the film was taken out of the drying oven and washed in water.

[0057] <Example 2>

[0058] In Example 2, a composite semipermeable membrane was prepared in the same manner as in Example 1 except for the composition of the MPD solution. The MPD solution of Example 2 contained distilled water as a solvent, 0.75 mass % MPD, 0.15 mass % SLS, 1.5 mass % CSA, 0.75 mass % TEA, 6 mass % IPA, and 0.03 mass % CNF. The CNF content was 0.12 mass % relative to the aromatic polyamide. When the MPD solutions of Example 1 and Example 2 were compared, the main difference in Example 2 was that CNF was used as an additive together with IPA.

[0059] <Comparative Example 1>

[0060] In Comparative Example 1, a composite semipermeable membrane was produced without using IPA. The method for producing the composite semipermeable membrane of Comparative Example 1 was carried out under the same conditions as those of the method of Example 1 except that the MPD solution did not contain IPA.

[0061] [evaluate]

[0062] <Measurement of cross-sectional shape>

[0063] For the composite semipermeable membranes of Example 1, Example 2 and Comparative Example 1, the composite semipermeable membranes were sliced ​​by cryo-ultrathin sectioning, and the cross-sectional shapes were measured by TEM. The cross-sectional shapes of the composite semipermeable membranes were measured under the above-mentioned measurement conditions except for changing the magnification. The measurement magnifications were 2000 times, 8000 times, and 20000 times.

[0064] In all three composite semipermeable membranes, it can be confirmed that a separation functional layer having a pleated structure of multiple units is formed on the porous supporting layer. In addition, in Comparative Example 1, the portion where the units overlap in the thickness direction is formed only in a portion of the separation functional layer, whereas in Examples 1 and 2, a multi-layer pleated structure where multiple units overlap in the thickness direction is formed on the surface of the separation functional layer as a whole. In addition, the cross-sectional area of ​​the units in Examples 1 and 2 is larger than that in Comparative Example 1. These trends are the same in two different measurement areas. In summary, it can be confirmed that the separation functional layer prepared by adding 10% by mass of IPA and 0.03% by mass of CNF to the MPD solution has a larger cross-sectional area of ​​the units than the separation functional layer to which no additives are added, and a multi-layer pleated structure is formed on the surface as a whole.

[0065] <Distribution of unit cross-sectional area>

[0066] The images of the composite semipermeable membranes of Example 1, Example 2, and Comparative Example 1 measured using TEM under the measurement conditions of the above-mentioned embodiment were subjected to image analysis by the method of the above-mentioned embodiment. Figures 4 to 6 The distribution of the cross-sectional area of ​​the unit formed in the separation functional layer of the three composite semipermeable membranes is shown. Figures 4 to 6 The vertical axis represents the total number of cells in two different regions of 2.8 μm×2.8 μm and the total value of the total area. Figure 4 The horizontal axis represents the cross-sectional area of ​​each unit, and the vertical axis represents the cumulative cross-sectional area of ​​units that are smaller than the cross-sectional area shown on the horizontal axis. Figure 4 As shown, 8000nm is obtained 2 When the cumulative cross-sectional area of ​​the cells is calculated below, it can be confirmed that the cross-sectional area of ​​the cells of the separation functional layer of Examples 1 and 2 is about twice as large as the cross-sectional area of ​​the cells of the separation functional layer of Comparative Example 1.

[0067] Figure 5 The horizontal axis represents the range of the cross-sectional area per unit, and the vertical axis represents the sum of the cross-sectional areas of all units within the range represented by the horizontal axis. Figure 6 The horizontal axis represents the range of the cross-sectional area of ​​each unit, and the vertical axis represents the total number of all units whose cross-sectional areas are within the range shown on the horizontal axis. Figure 5 and Figure 6 As shown, it can be confirmed that the cross-sectional area is 1000nm 2 ~8000nm 2 In the range of 1000 nm, the total number of units of the separation functional layer of Examples 1 and 2 is greater than that of the separation functional layer of Comparative Example 1, and the total area is also greater. Specifically, in Example 1, the cross-sectional area is 1000 nm. 2 ~8000nm 2The total number of units is about 80, and the total area of ​​the unit is about 2.47×10 5 nm 2 In Example 2, the cross-sectional area is 1000 nm 2 ~8000nm 2 The total number of units is about 79, and the total area of ​​the unit is about 2.15×10 5 nm 2 In Comparative Example 1, the cross-sectional area is 1000 nm 2 ~8000nm 2 The total number of units is about 41, and the total area of ​​the unit is 1.02×10 5 nm 2 .

[0068] <Determination of desalination and water permeability>

[0069] The salt rejection and water permeability of the composite semipermeable membranes of Example 1, Example 2 and Comparative Example 1 were measured by the following methods.

[0070] <Desalination performance>

[0071] A 0.05% NaCl aqueous solution at 25°C was supplied to the composite semipermeable membrane using a cross-flow device at a flow rate of 300 ml / min and an operating pressure of 0.75 MPa. The desalination rate was calculated by measuring the salt concentrations of the supply solution and the permeate solution 2 hours after the start of the supply of the NaCl aqueous solution.

[0072] Salt rejection rate (%) = (1-salt concentration of permeate solution / salt concentration of feed solution) × 100

[0073] <Water Permeability>

[0074] The water permeability was measured from 1 hour and 30 minutes after the start of supply of the NaCl aqueous solution to 2 hours after the water permeation for 30 minutes, and the permeation flux was calculated using the following formula.

[0075] Permeation flux (m 3 / m 2 / d) = (30-minute water permeability (m 3 ) / 30)×60×24) / membrane effective area (m 2 )

[0076] [Table 1]

[0077]

[0078] As shown in Table 1, the salt rejection rate in Comparative Example 1 exceeded 98%. The permeate flux was less than about 1.2 m 3 / m 2 / d. In contrast, in Example 1, where the content of IPA relative to the MPD solution was 10% by mass, the desalination rate was maintained at more than 96%, and the permeation flux was about twice that of Comparative Example 1. In Example 2, where the content of CNF relative to the MPD solution was 0.03% by mass, the desalination rate exceeded 98%, and the permeation flux was also about twice that of Comparative Example 1, similarly to Example 1. Based on this result, it can be confirmed that the cross-sectional area is 1000nm 2 ~8000nm 2 The unit 21 contains about 80 cells (total area is about 2.47×10 5 nm 2 ) of Example 1 and comprising about 79 (with a total area of ​​about 2.15×10 5 nm 2 ) of the composite semipermeable membrane 1 of Example 2 with a cross-sectional area of ​​2000nm 2 ~8000nm 2 The unit 21 contains about 41 cells (total area is about 1.02×10 5 nm 2 ) compared to the comparative example, the water permeability is about 2 times higher.

[0079] Explanation of symbols

[0080] 1 Composite semipermeable membrane

[0081] 10. Porous support layer

[0082] 20 Separation functional layer

[0083] 21 units.

Claims

1. A composite semipermeable membrane comprising a porous supporting layer and a separation functional layer containing aromatic polyamide formed on the porous supporting layer, The separation function layer has a plurality of hollow cells, and in cross-sectional observation at a magnification of 8000 times using a transmission electron microscope, the cross-sectional area is 1000 nm. 2 ~8000nm 2 The total value of each area of ​​the unit in two different regions of 2.8 μm×2.8 μm is 1.8×10 5 nm 2 ~1.0×10 7 nm 2 The thickness of the separation functional layer is 100nm to 2000nm. The composite semipermeable membrane is manufactured by a manufacturing method including a porous support layer manufacturing step, an impregnation step, a polymerization step and a post-treatment step. In the impregnation step, the m-phenylenediamine solution is impregnated into the porous support. The m-phenylenediamine solution contains 10% to 15% by mass of isopropanol, Alternatively, the meta-phenylenediamine solution contains 6.0% to 15% by mass of isopropyl alcohol, and the separation functional layer contains 0.001% to 0.12% by mass of cellulose nanofibers based on the aromatic polyamide.

2. A composite semipermeable membrane comprising a porous supporting layer and a separation functional layer containing aromatic polyamide formed on the porous supporting layer, The separation function layer has a plurality of hollow cells, and in cross-sectional observation at a magnification of 8000 times using a transmission electron microscope, the cross-sectional area is 1000 nm. 2 ~8000nm 2 The units include 60 to 3500 in total in two different regions of 2.8 μm×2.8 μm, The thickness of the separation functional layer is 100nm to 2000nm. The composite semipermeable membrane is manufactured by a manufacturing method including a porous support layer manufacturing step, an impregnation step, a polymerization step and a post-treatment step. In the impregnation step, the m-phenylenediamine solution is impregnated into the porous support. The m-phenylenediamine solution contains 10% to 15% by mass of isopropanol, Alternatively, the meta-phenylenediamine solution contains 6.0% to 15% by mass of isopropyl alcohol, and the separation functional layer contains 0.001% to 0.12% by mass of cellulose nanofibers based on the aromatic polyamide.

3. The composite semipermeable membrane according to claim 1 or 2, wherein The separation functional layer contains 0.001% by mass to 1% by mass of cellulose nanofibers based on the aromatic polyamide.

Images