Composite semipermeable membrane, composite semipermeable membrane element, water treatment system, and method for manufacturing a composite semipermeable membrane

Abstract

The present invention relates to a composite semipermeable membrane comprising a porous support layer and a separation function layer provided on the porous support layer, wherein the separation function layer contains an aromatic polyamide having a structure represented by general formula (I) described in the specification, the aromatic polyamide having nitro groups, and surface analysis of the separation function layer by X-ray photoelectron spectroscopy, in which the ratio A / B of the number of nitrogen atoms A derived from the nitro groups to the total number of nitrogen atoms B is 0.002 or more and 0.100 or less.

Description

[Technical Field]

[0001] The present invention relates to a composite semipermeable membrane, a composite semipermeable membrane element, a water treatment system, and a method for producing a composite semipermeable membrane, all of which are useful for the selective separation of liquid mixtures. [Background technology]

[0002] Regarding the separation of liquid mixtures, various techniques exist for removing substances (e.g., salts) dissolved in a solvent (e.g., water). In particular, the use of membrane separation methods has been expanding in recent years as a process for saving energy and resources. Membranes used in membrane separation methods include microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes. These membranes are used, for example, to obtain drinking water from water containing salts or harmful substances, to produce industrial ultrapure water, to treat wastewater, and to recover valuable materials.

[0003] Most reverse osmosis and nanofiltration membranes currently on the market are composite semipermeable membranes in which a separation functional layer having the ability to separate salts and other substances is coated on a support membrane. There are two types of such composite semipermeable membranes: those having an active layer formed by crosslinking a gel layer and a polymer on the support membrane, and those having an active layer formed by polycondensation of monomers on the support membrane. Among the latter composite semipermeable membranes having an active layer formed by polycondensation of monomers, composite semipermeable membranes having a separation functional layer containing a crosslinked polyamide obtained by the polycondensation reaction of a polyfunctional amine and a polyfunctional acid halide are widely used as separation membranes with high water permeability and selective separation (see Patent Document 1). These composite semipermeable membranes require higher salt removal capabilities so that treated water of higher quality can be obtained from water containing salt.

[0004] As a means of improving the salt removal properties of composite semipermeable membranes, post-treatment methods are known that convert the amine ends of crosslinked aromatic polyamides by, for example, a diazo coupling reaction, contact with a bromine-containing free chlorine aqueous solution, or contact with a low-temperature aqueous solution containing aldehydes or epoxides (see Patent Documents 2, 3, and 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2010 / 096563 [Patent Document 2] Japanese Unexamined Patent Publication No. 2007-090192 [Patent Document 3] Japanese Unexamined Patent Publication No. 2001-259388 [Patent Document 4] International Publication No. 2006 / 051888 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] The salt removal performance and water permeability of composite semipermeable membranes generally have a trade-off relationship. Particularly in reverse osmosis membranes and nanofiltration membranes, increasing salt removal performance greatly impairs water permeability. When water permeability decreases, it is necessary to increase the operating pressure, which leads to an increase in operating cost. Although Patent Document 2 describes a method for obtaining permeated water with a low salt concentration, it cannot exhibit sufficient salt removal performance in the treatment of raw water with a high salt concentration such as seawater. The composite semipermeable membranes described in Patent Documents 3 and 4 have low water permeability and need to be operated at high pressure to obtain a sufficient amount of produced water.

[0007] Accordingly, an object of the present invention is to provide a composite semipermeable membrane that achieves both salt removal performance and water permeability. [Means for Solving the Problems]

[0008] In order to solve the above problems, the present invention includes the following configurations [1] to

[13] . [1] A composite semipermeable membrane comprising a porous support layer and a separation functional layer provided on the porous support layer, wherein the separation functional layer contains an aromatic polyamide having a structure represented by the following general formula (I), the aromatic polyamide has a nitro group, and in surface analysis on the separation functional layer side by X-ray photoelectron spectroscopy, a ratio A / B of the number of nitrogen atoms A derived from the nitro group to the total number of nitrogen atoms B is 0.002 or more and 0.100 or less.

[0009] [ka]

[0010] [In general formula (I), Ar1 to Ar3 are each independently substituted aromatic rings having 5 to 14 carbon atoms, R1 is the structure represented by the following general formula (II) and / or general formula (III), and R2 to R4 are each independently a hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms that may be substituted.]

[0011] [ka]

[0012] [ka]

[0013] [In general formulas (II) and (III), W1 and W2 are independently an oxygen atom, a sulfur atom, or NV (where N is a nitrogen atom), and V is a hydrogen atom or an aliphatic chain with 1 to 10 carbon atoms, which may be substituted. In general formula (II), Z1 is a single bond or an atomic group with 1 to 12 carbon atoms, which may be substituted, and Z2 is an atomic group with 1 to 12 carbon atoms, with the sum of the carbon atoms in Z1 and Z2 being 12 or less. In general formula (III), Z3 is a single bond or an atomic group with 1 to 12 carbon atoms, which may be substituted. Furthermore, all functional groups included in Z1 to Z3 are neutral or positively charged groups.] [2] The composite semipermeable membrane described in [1] above, wherein R1 in the above general formula (I) is the above general formula (III), W2 in the above general formula (III) is an oxygen atom, and Z3 is a structure represented by the following general formula (IV).

[0014] [ka]

[0015] [In general formula (IV), n is an integer from 1 to 6, X1 and X2 in each repeating unit are independently a carbon atom or a nitrogen atom, and the cis-trans isomers of the double bond between X1 and X2 are not limited. L1 and L2 in each repeating unit are independently a hydrogen atom, a halogen atom, an optionally substituted C1-C6 hydrocarbon, or a lone pair of electrons, and L1 and L2 may be directly or indirectly bonded to form a cyclic structure, and the sum of the carbon numbers of all L1 and L2 is 12n or less.] [3] The composite semipermeable membrane according to [1] or [2] above, wherein the aromatic polyamide includes a structure represented by the following general formula (VIII).

[0016] [ka]

[0017] [In general formula (VIII), Ar4 to Ar6 are each an aromatic ring having 5 to 14 carbon atoms, which may be independently substituted, and R5 to R9 are each an independently hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms, which may be independently substituted.] [4] The composite semipermeable membrane according to [2] or [3] above, wherein n in the general formula (IV) above is 1 or more and 2 or less. [5] A composite semipermeable membrane according to any of [2] to [4] above, wherein the structure represented by the above general formula (III) is the structure represented by the following general formula (V).

[0018] [ka]

[0019] [In general formula (V), Y1 to Y4 are each independently a hydrogen atom, an optionally substituted hydrocarbon having 1 to 4 carbon atoms, an ester group, or a halogen, and the total number of carbon atoms of Y1 to Y4 is 6 or less. Y1 to Y4 may be directly or indirectly bonded to form a cyclic structure.] [6] The composite semipermeable membrane described in [5] above, wherein Y1 to Y4 in the general formula (V) above are hydrogen atoms. [7] A composite semipermeable membrane according to any of [1] to [6] above, wherein, in surface analysis of the separation functional layer by TOF-SIMS in negative secondary ion mode, the ratio D / C of the signal intensity D at m / z = 45.99 to the signal intensity C at m / z = 107.06 is 1.0 or more and 10 or less. [8] b when measured from the surface on the separation functional layer side. * A composite semipermeable membrane as described in [1] to [7] above, wherein the ratio is 1.5 or more and 20 or less. [9] In the surface analysis of the separation functional layer side by TOF-SIMS in positive second-order ion mode, the ratio G / F of the signal intensity G of the fragment with the maximum signal intensity among the fragments derived from the structure of R1 in the general formula (I) above, with respect to the signal intensity F at m / z = 75.02, is 7.5 × 10⁻⁶. -3 The above 1.2 × 10 -1 The composite semipermeable membrane described in any of the above [1] to [8] is as follows:

[10] A composite semipermeable membrane according to any of [1] to [9] above, wherein the zeta potential of the surface on the separation functional layer side at pH 3.0 is between -15.0 mV and 10.0 mV.

[11] A composite semipermeable membrane element comprising a composite semipermeable membrane as described in any of [1] to

[10] above.

[12] A water treatment system that separates the supply water into concentrated water and fresh water using the composite semipermeable membrane element described in

[11] above.

[13] A method for producing a composite semipermeable membrane comprising a porous support layer and a separation functional layer containing an aromatic polyamide on the porous support layer, the method comprising the following steps (b1) and (b2). Step (b1): A step of bringing the separation functional layer into contact with a processing solution containing a compound represented by the following general formula (XII). Step (b2): A step of bringing the separation functional layer into contact with a processing solution containing nitrate ions and having a pH of 2 or lower.

[0020] [ka]

[0021] [In general formula (XII), Z4 and Z5 are each independently a formyl group, an acetal group, a hemiaminal group, or an aminal group, n is an integer from 1 to 6, X1 and X2 in each repeating unit are each independently a carbon atom or a nitrogen atom, and the cis-trans isomers of the double bond between X1 and X2 are not limited. L1 and L2 in each repeating unit are each independently a hydrogen atom, a halogen atom, an optionally substituted C1-C6 hydrocarbon, or a lone pair of electrons, and L1 and L2 may be directly or indirectly bonded to form a cyclic structure, and the sum of the carbon numbers of all L1 and L2 is 12n or less.] [Effects of the Invention]

[0022] According to the present invention, a composite semipermeable membrane that achieves both salt removal properties and water permeability can be obtained. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described in detail below, but the present invention is not limited thereto.

[0024] In this specification, for example, "mass%" and "weight%" are synonymous, and "parts by mass" and "parts by weight" are synonymous.

[0025] (1) Composite semipermeable membrane The composite semipermeable membrane according to this embodiment comprises a porous support layer and a separation function layer provided on the porous support layer. Hereinafter, "vertical direction" refers to the thickness direction of the composite semipermeable membrane. The separation function layer is positioned "on top" of the support layer. The porous support layer of the composite semipermeable membrane according to this embodiment may be formed on a substrate. In this case, the configuration including the substrate and the porous support layer formed on the substrate is referred to as the "support membrane".

[0026] The separation functional layer substantially possesses separation capabilities, while the porous support layer substantially does not possess separation capabilities for ions, etc., and can provide strength to the separation functional layer.

[0027] (1-1) Support membrane The support film includes a substrate and a porous support layer.

[0028] Examples of materials for the base material include fabrics made from polyester polymers, polyamide polymers, polyolefin polymers, mixtures thereof, or copolymers. Among these, fabrics made from polyester polymers, which have high mechanical and thermal stability, are preferred. The fabric can preferably be in the form of a long-fiber nonwoven fabric, a short-fiber nonwoven fabric, or a woven or knitted fabric.

[0029] The porous support layer has numerous interconnected pores. The pore diameter and pore diameter distribution of the porous support layer are not particularly limited. For example, a porous support layer with a symmetrical structure consisting of uniform pore diameters, or an asymmetrical structure in which the pore diameter gradually increases from one surface to the other, and in which the pore diameter on the surface with smaller pore diameters is 0.1 to 100 nm, is preferred.

[0030] As the material for the porous support layer, homopolymers or copolymers such as polysulfone (hereinafter referred to as "PSf"), polyethersulfone, polyamide, polyester, cellulose polymers, vinyl polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide can be used alone or in blends. Here, examples of cellulose polymers include cellulose acetate and cellulose nitrate, and examples of vinyl polymers include polyethylene, polypropylene, polyvinyl chloride, and polyacrylonitrile. Among these, homopolymers or copolymers such as PSf, polyamide, polyester, cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polyphenylene sulfide, and polyphenylene sulfide sulfone are preferred, and PSf, cellulose acetate, polyphenylene sulfide sulfone, or polyphenylene sulfone are more preferred. Among these, PSf is particularly preferred because it has high chemical, mechanical, and thermal stability and is easy to mold.

[0031] The weight-average molecular weight (hereinafter referred to as "Mw") of PSf is preferably between 10,000 and 200,000, and more preferably between 15,000 and 100,000. When the Mw of PSf is 10,000 or more, desirable mechanical strength and heat resistance can be obtained as a porous support layer. On the other hand, when the Mw of PSf is 200,000 or less, the viscosity of the porous support layer stock solution is within an appropriate range, and good moldability can be achieved.

[0032] The sum of the thicknesses of the substrate and the porous support layer, i.e., the thickness of the support film, affects the strength of the composite semipermeable membrane and the packing density when it is used as an element. To obtain good mechanical strength and packing density, the thickness of the support film is preferably 30 μm to 300 μm, and more preferably 100 μm to 220 μm. The thickness of the porous support layer is preferably 20 μm to 100 μm. The thickness of the support film and the porous support layer are determined by calculating the average value of 20 thicknesses measured at 20 μm intervals in a direction perpendicular to the thickness direction (the surface direction of the film) during cross-sectional observation.

[0033] (1-2) Separation functional layer The separation layer is responsible for the separation of solutes and contains aromatic polyamide. Preferably, the separation layer is primarily composed of aromatic polyamide.

[0034] "Mainly composed of aromatic polyamide" means that aromatic polyamide accounts for 50% by mass or more in the separation functional layer. Preferably, the proportion of aromatic polyamide in the separation functional layer is 80% by mass or more, more preferably 90% by mass or more, and even more preferably the separation functional layer is substantially composed solely of aromatic polyamide. "The separation functional layer is substantially composed solely of aromatic polyamide" means that aromatic polyamide accounts for 99% by mass or more in the separation functional layer. Note that the above proportions are values ​​measured using the separation functional layer in a dry state.

[0035] The aromatic polyamide contained in the separation functional layer of the composite semipermeable membrane according to this embodiment may be an aramid compound, but it may also contain non-aromatic moieties in its molecular structure. From the viewpoint of rigidity, chemical stability, and durability against operating pressure, the aromatic polyamide is more preferably a crosslinked aromatic polyamide, and even more preferably a crosslinked total aromatic polyamide consisting only of aromatic polyamides.

[0036] "Cross-linked aromatic polyamide" means that the aromatic polyamide, which is a polymer of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide, forms a cross-linked structure. For example, the aromatic polyamide may form a cross-linked structure via a cross-linking agent, and at least one of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide may be trifunctional or more, and the aromatic polyamide may form a network-like cross-linked structure. In particular, it is more preferable that at least one of the polyfunctional aromatic amine and the polyfunctional aromatic acid halide is trifunctional or more, and the aromatic polyamide forms a network-like cross-linked structure.

[0037] A "polyfunctional aromatic amine" refers to an aromatic amine that has two or more amino groups, at least one of either a primary amino group or a secondary amino group, in a single molecule, and at least one of these amino groups is a primary amino group. The aromatic rings derived from polyfunctional aromatic amines correspond to Ar1 and Ar3 in general formula (I) and Ar4 and Ar6 in general formula (VIII), which will be described later.

[0038] Examples of polyfunctional aromatic amines include o-phenylenediamine, m-phenylenediamine (hereinafter referred to as "m-PDA"), p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, o-diaminopyridine, m-diaminopyridine, p-diaminopyridine, and other polyfunctional aromatic amines in which two amino groups are bonded to the aromatic ring in an ortho, meta, or para position; 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 3-aminobenzylamine, and 4-aminobenzylamine. In particular, considering the selective separation properties, water permeability, and heat resistance of the membrane, m-PDA, p-phenylenediamine, and 1,3,5-triaminobenzene are preferred. The polyfunctional aromatic amine constituting the aromatic polyamide may be one type or two or more types.

[0039] A "polyfunctional aromatic acid halide" refers to an aromatic acid halide that has at least two halogenated carbonyl groups in one molecule. The aromatic rings derived from polyfunctional aromatic acid halides correspond to Ar2 in general formula (I) and Ar5 in general formula (VIII), which will be described later.

[0040] Examples of trifunctional acid halides include trimesic acid chloride, and examples of bifunctional acid halides include biphenyldicarboxylic acid dichloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, and naphthalenedicarboxylic acid chloride. Among acid halides, acid chlorides are preferred, and in particular, trimesic acid chloride (hereinafter referred to as "TMC"), an acid halogen of 1,3,5-benzenetricarboxylic acid, isophthalic acid chloride, an acid halogen of 1,3-benzenedicarboxylic acid, and terephthalic acid chloride, an acid halogen of 1,4-benzenedicarboxylic acid, are preferred in terms of economy, availability, ease of handling, and reactivity.

[0041] To prevent the substance to be separated from penetrating into the interior of the composite semipermeable membrane, the separation functional layer is preferably located on the surface side of the composite semipermeable membrane, and more preferably on the primary side of filtration.

[0042] The separation functional layer in the composite semipermeable membrane according to this embodiment contains an aromatic polyamide having a structure represented by the following general formula (I).

[0043] [ka]

[0044] In the above general formula (I), Ar1 to Ar3 are each independently substituted aromatic rings having 5 to 14 carbon atoms, R1 is a structure represented by the following general formula (II) and / or general formula (III), and R2 to R4 are each independently a hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms that may be substituted.

[0045] [ka]

[0046] [ka]

[0047] In general formulas (II) and (III), W1 and W2 are independently an oxygen atom, a sulfur atom, or NV (where N is a nitrogen atom), and V is a hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms, which may be substituted. In general formula (II), Z1 is a single bond or an atomic group having 1 to 12 carbon atoms, which may be substituted, and Z2 is an atomic group having 1 to 12 carbon atoms, with the sum of the carbon atoms in Z1 and Z2 being 12 or less. In general formula (III), Z3 is a single bond or an atomic group having 1 to 12 carbon atoms, which may be substituted. Furthermore, all functional groups included in Z1 to Z3 are neutral or positively charged groups.

[0048] Examples of the Z1 atomic group include alkylene groups such as methylene, ethylene, and propylene groups; oxyalkylene groups such as oxymethylene and oxyethylene groups; alkyleneamino groups such as aminomethylene and aminoethylene groups; aromatic groups such as phenylene and naphthylene groups; and groups having heteroatoms such as halogens and nitrogen atoms as substituents.

[0049] Examples of Z2 atomic groups include alkyl groups such as methyl, ethyl, and propyl groups, alkoxy groups such as methoxy and ethoxy groups, aromatic groups such as phenyl and naphthyl groups, and those having heteroatoms such as halogens and nitrogen atoms as substituents.

[0050] In the above general formula (II), W1 is preferably an oxygen atom. Z1 is preferably a single bond, an alkylene group, or an alkylene amino group, and more preferably a single bond or an alkylene amino group. Z2 is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom. Furthermore, the total number of carbon atoms of Z1 and Z2 is preferably 3 or less. When the total number of carbon atoms is 3 or less, the size of the atomic group contributes to the formation of a pore size that is favorable for improving removalability, and salt removal performance is improved. It is even more preferable that at least one of Z1 and Z2 has a heteroatom. This is because the selective permeability of water molecules is increased due to the effect of electronic interaction with water molecules.

[0051] In the above general formula (I), R1 is preferably a structure represented by the above general formula (III), where W2 is an oxygen atom and Z3 is a structure represented by the following general formula (IV).

[0052] [ka]

[0053] In the above general formula (IV), n is an integer from 1 to 6, X1 and X2 in each repeating unit are independently a carbon atom or a nitrogen atom, and the cis-trans isomers of the double bond between X1 and X2 are not limited. L1 and L2 in each repeating unit are independently a hydrogen atom, a halogen atom, a substituted C1-C6 hydrocarbon, or a lone pair of electrons, and L1 and L2 may be directly or indirectly bonded to form a cyclic structure, and the sum of the carbon numbers of all L1 and L2 is 12n or less.

[0054] The salt removal performance is improved when the separation functional layer in the composite semipermeable membrane has the structure represented by the above general formula (IV). In the above general formula (I), Ar1 to Ar3 are preferably C6 aromatic rings, i.e., benzene rings, from the viewpoint of ensuring an appropriate free volume for water permeation in the separation functional layer. The benzene ring may be unsubstituted or may have substituents. Examples of substituents on the benzene ring include amino groups, carboxyl groups, methyl groups, chloro groups, and bromo groups, and other substituents may be present as long as they do not hinder the effects of the present invention.

[0055] In the above general formula (I), R2 to R4 are preferably hydrogen atoms, from the viewpoint of forming hydrogen bonds between aromatic polyamides constituting the separation functional layer and contributing to improved salt removal performance.

[0056] In the above general formula (IV), n is preferably 1 or more and 2 or less, and more preferably 1, from the viewpoint of easily forming a pore structure in the separation functional layer that prevents salt from permeating and allows water to permeate selectively.

[0057] In the structure of general formula (IV) above, the cyclic structure formed by the direct or indirect bonding of L1 and L2 may be an aromatic ring such as a benzene ring or a naphthalene ring. Furthermore, if multiple L1 and L2 rings are present, any of the L1 and L2 rings may be directly or indirectly bonded to each other.

[0058] Furthermore, the structure represented by the above general formula (III) is preferably the structure represented by the following general formula (V).

[0059] [ka]

[0060] In the above general formula (V), Y1 to Y4 are each independently a hydrogen atom, a hydrocarbon having 1 to 4 carbon atoms which may be substituted, an ester group, or a halogen, and the total number of carbon atoms of Y1 to Y4 is 6 or less. Y1 to Y4 may be directly or indirectly bonded together to form a cyclic structure.

[0061] The structure of general formula (V) above corresponds to the structure in general formula (IV) above where n is 1, X1 and X2 are carbon atoms, and L1 and L2 are directly bonded to form a benzene ring, and the structure in general formula (III) above where W2 is an oxygen atom. In this way, the inclusion of a benzene ring in R1 ensures the chemical stability of the structure, and at the same time, the rigid ring structure contributes to the formation of a pore structure that allows water to selectively permeate.

[0062] In the above general formula (V), it is preferable that Y1 to Y4 are all hydrogen atoms. When Y1 to Y4 are all hydrogen atoms, the polyamide constituting the separation functional layer fills the space more densely, resulting in higher salt removal performance.

[0063] The structure represented by the above general formula (II) and / or general formula (III), that is, the presence or absence of R1 in general formula (I) and its amount, can be evaluated by surface analysis of the separation functional layer side by TOF-SIMS. In TOF-SIMS, Bi3 is used as the primary ion beam on the separation functional layer side of the film sample under vacuum. ++ When irradiated, secondary ions are emitted from a few nanometers of the sample surface. By introducing these secondary ions into a time-of-flight (TOF) mass spectrometer, information about the chemical structure of the sample surface can be obtained. Mass spectrometry for the analysis of the presence and abundance of the structure represented by general formula (II) and / or general formula (III) is performed in positive secondary ion mode.

[0064] Specifically, Bi3 is placed on the surface of the separation functional layer of the composite semipermeable membrane. ++ When irradiated, some of the covalent bonds of the aromatic polyamide constituting the separation functional layer are cleaved, yielding fragments. Here, from the structure derived from R1 of general formula (I), i.e., the structure of general formula (II), a fragment represented by the following general formula (VI) is obtained, and from the structure of general formula (III), a fragment represented by the following general formula (VII) is obtained.

[0065] [ka]

[0066] [ka]

[0067] In general formulas (VI) and (VII), W1 and W2 are independently an oxygen atom, a sulfur atom, or NV (where N is a nitrogen atom), and V is a hydrogen atom or an aliphatic chain with 1 to 10 carbon atoms, which may be substituted. In general formula (VI), Z1 is a single bond or an atomic group with 1 to 12 carbon atoms, which may be substituted, and Z2 is an atomic group with 1 to 12 carbon atoms, with the sum of the carbon atoms in Z1 and Z2 being 12 or less. In general formula (VII), Z3 is a single bond or an atomic group with 1 to 12 carbon atoms, which may be substituted. Furthermore, all functional groups in Z1 to Z3 are neutral or positively charged groups. Note that the "·" in the upper right corner of the chemical structural formula represents a radical; for example, "··" indicates the presence of two radicals in the general formula. The explanation for the Z1 and Z2 atomic groups is the same as in the general formula (II) described above.

[0068] Let's look at an example where the structure of R1 is general formula (II). If the structure of R1 is derived from sarcosine, the signal is obtained at m / z=72.05; if it is derived from N-ethylglycine, it is obtained at m / z=86.06; if it is derived from N-propylglycine, it is obtained at m / z=100.08; if it is derived from acetic acid, it is obtained at m / z=58.03; if it is derived from propionic acid, it is obtained at m / z=72.05; and if it is derived from butyric acid, it is obtained at m / z=86.06.

[0069] An example is given below for the case where the structure of R1 is represented by general formula (III). When the structure of R1 is derived from o-phthalaldehyde, a signal is obtained at m / z=132.04; when derived from malealdehyde, at m / z=82.03; when derived from 3-methylphthalaldehyde, at m / z=146.06; when derived from 4-bromophthalaldehyde, at m / z=209.96; when derived from methyl 3,4-diformylbenzoate, at m / z=190.05; when derived from benzene-1,2,4,5-tetracarbaldehyde, at m / z=186.04; when derived from benzo[d][1,3]dioxole-4,5-dicarbaldehyde, at m / z=176.03; when derived from naphthalene-2,3-dicarbaldehyde, at m / z=182.06; and when derived from [1,1'-biphenyl]-2,2'-dicarbaldehyde, at m / z=208.08, respectively.

[0070] In the surface analysis on the separation functional layer side of the composite semipermeable membrane according to the present embodiment by TOF-SIMS in positive secondary ion mode, among the fragments derived from the structure of R1 in the above general formula (I) with respect to the signal intensity F at m / z=75.02, the ratio G / F of the signal intensity G of the fragment with the maximum signal intensity is 7.5×10 -3 or more and 1.2×10 -1 or less is preferable, 1.1×10 -2 or more and 1.1×10 -1 or less is more preferable, 1.5×10 -2 or more and 7.5×10 -2 or less is even more preferable, and 2.0×10 -2 or more and 7.5×10 -2 or less is particularly preferable. In a composite semipermeable membrane having a separation functional layer containing an aromatic polyamide, when surface analysis is performed on the separation functional layer side by TOF-SIMS in positive secondary ion mode, a fragment derived from Ar2 in general formula (I) is obtained. When Ar2 is a trisubstituted benzene ring, the main fragment obtained is C6H3 +This is obtained as a signal with m / z = 75.02. At this time, the ratio G / F reflects the ratio of the structure represented by general formula (II) or general formula (III) to the polyfunctional aromatic carboxylic acid skeleton constituting the aromatic polyamide in the separation functional layer. The ratio G / F is 7.5 × 10 -3 As a result, the composite semipermeable membrane exhibits better salt removal properties because it sufficiently contains the structure represented by general formula (II) or general formula (III). Furthermore, the ratio G / F is 1.2 × 10⁻⁶. -1 The following conditions can suppress the reduction in permeability caused by the excessive introduction of structures represented by general formula (II) or general formula (III). The ratio G / F value can be controlled, for example, by the conditions of step (b1) described in "(2-3) Modification process of the separation functional layer" described later.

[0071] The aromatic polyamide constituting the separation functional layer of the composite semipermeable membrane according to this embodiment further has nitro groups. The presence of nitro groups in the aromatic polyamide in the separation functional layer prevents the hyperformation of ion pairs formed by the terminal amino groups and terminal carboxyl groups of the aromatic polyamide, thereby suppressing the disruption of water channels, which are pathways for water molecules, and thus improving water permeability.

[0072] In particular, from the viewpoint of preventing hyperformation of ion pairs between terminal amino groups and terminal carboxyl groups of aromatic polyamides, it is preferable that a nitro group be present on the same aromatic ring as the aromatic ring containing the amino group, as shown in the general formula (VIII) below.

[0073] [ka]

[0074] In general formula (VIII), Ar4 to Ar6 are each an aromatic ring having 5 to 14 carbon atoms which may be substituted independently, and R5 to R9 are each an independent hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms which may be substituted independently.

[0075] The presence and abundance of nitro groups can be evaluated by X-ray photoelectron spectroscopy (hereinafter referred to as "XPS"). The XPS methods exemplified in "Journal of Polymer Science", Vol. 26, 559-572 (1988) and "Journal of the Adhesion Society of Japan", Vol. 27, No. 4 (1991) can be used.

[0076] In the composite semipermeable membrane according to this embodiment, the ratio A / B of the number of nitrogen atoms A derived from nitro groups to the total number of nitrogen atoms B, as observed in surface analysis of the separation functional layer side by XPS, is 0.002 or more and 0.100 or less. When the ratio A / B is 0.002 or more, high water-removal properties are obtained. Furthermore, when the ratio A / B is 0.100 or less, high salt removal properties are maintained. From the above viewpoint, a ratio A / B value of 0.006 or more and 0.020 or less is preferred.

[0077] The ratio A / B can be controlled, for example, by the conditions of step (b2) described in "(2-3) Modification process of the separation function layer" below.

[0078] In the composite semipermeable membrane according to this embodiment, in surface analysis of the separation functional layer by TOF-SIMS in negative secondary ion mode, the ratio D / C of the signal intensity D at m / z = 45.99 to the signal intensity C at m / z = 107.06 is preferably 1.0 or more and 10 or less, and more preferably 1.5 or more and 6.0 or less.

[0079] In a composite semipermeable membrane having a separation functional layer containing aromatic polyamide, surface analysis of the separation functional layer side by TOF-SIMS in negative secondary ion mode yields fragments derived from nitro groups and fragments derived from general formula (VIII), which is a structure containing nitro groups. In addition, peaks derived from Ar1 of the substructure of general formula (IX) below, which is present in the separation functional layer, are also obtained.

[0080] [ka]

[0081] In the above general formula (IX), Ar1 to Ar3 are each an aromatic ring having 5 to 14 carbon atoms which may be substituted independently, and R2 to R4 are each an independent hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms which may be substituted independently.

[0082] In the above general formula (IX), when R2 is a hydrogen atom, the ionic formula of the main fragment obtained from the structure containing Ar1 in the above general formula (IX) is C6H7N2. - This is obtained as a signal with m / z = 107.06. Furthermore, the ionic formula of the fragment derived from the nitro group is NO2 - This is obtained as a signal with m / z = 45.99. In other words, the ratio D / C reflects the ratio of nitro groups to the polyfunctional amine-terminal structures constituting the aromatic polyamide in the separation functional layer. When the ratio D / C is 1.0 or higher, the presence of nitro groups introduced into the aromatic ring containing the terminal amino group of the aromatic polyamide sufficiently inhibits the formation of ion pairs between the amino and carboxyl terminals, suppressing the disruption of water channels and thus exhibiting higher water permeability. Furthermore, when the ratio D / C is 10 or lower, the hydrogen bonding network between polyamides is not disrupted due to excessive introduction of nitro groups into the aromatic ring containing the terminal amino group of the aromatic polyamide, resulting in higher salt removal efficiency.

[0083] The D / C ratio also increases when the terminal amino group in the structure represented by general formula (IX) is chemically converted to the structure represented by general formula (II) and / or general formula (III). In this case as well, the same effect occurs as the ion pair between the amino terminus and the carboxy terminus is no longer formed due to the disappearance of the terminal amino group during the conversion. The D / C ratio can be controlled, for example, by the conditions of step (b2) described in "(2-3) Modification step of the separation functional layer" described later.

[0084] When the aromatic polyamide contained in the separation functional layer has a structure represented by general formula (VIII), Ar4 is substituted with both an electron-donating amino group and an electron-withdrawing nitro group. The presence of such a structure extends the π-conjugated system of the aromatic ring, promoting electron delocalization. This alters the energy levels of the frontier orbitals, shifting the wavelength of absorbed electromagnetic waves to the visible light region, which has lower energy than ultraviolet light. As a result, it absorbs visible light and emits color. In particular, light with wavelengths from blue to violet is absorbed, resulting in the emission of its complementary colors, yellow to orange. The surface color of the separation functional layer is determined according to JIS Z 8722:2009 (Method of measuring color) and JIS Z 8781-4:2013 (CIE 1976 L * a * b * As described in the color space, L * a * b * It is possible to express this using a color space, L * The value of a represents brightness, * and b * The value represents the hue. * A value greater than 0 indicates a high degree of redness, and a value less than 0 indicates a high degree of greenness. Also, b * A value greater than 0 indicates a high degree of yellowness, while a value less than 0 indicates a high degree of blueness. When the aromatic polyamide of the separation functional layer contains a structure represented by general formula (VIII), the surface on the separation functional layer side develops a yellowish-brown color, in which case b * When this value becomes positive, the amount of the structure represented by general formula (VIII) can be estimated based on its magnitude.

[0085] The composite semipermeable membrane according to this embodiment has a b value measured from the surface on the separation functional layer side. * It is preferable that the ratio is 1.5 or more and 20 or less, more preferably 2.0 or more and 15 or less, and even more preferably 3.0 or more and 10 or less. The separation functional layer contains a nitro group, and b * If it falls within the above range, it contains an appropriate amount of the structure represented by general formula (VIII), making it easier to obtain a composite semipermeable membrane that achieves both high water permeability and high salt removal performance. Note that the L on the surface of the separation functional layer *is 90 or more and 100 or less, a * It is preferable that the value is in the range of -3 or more and 3 or less. The chromaticity of the surface on the separation functional layer side is measured by the method described in "Chromaticity Measurement" of the Examples described later. b * This can be controlled, for example, by the conditions of step (b2) described in "(2-3) Modification of the Separation Functional Layer" later.

[0086] In this embodiment, the composite semipermeable membrane preferably has a zeta potential of -15.0 mV or more and 10.0 mV or less on the surface of the separation functional layer at pH 3.0, and more preferably 0 mV or more and 6.0 mV or less.

[0087] Zeta potential is a measure of the net fixed charge on the surface of a flat sample. The aromatic polyamide contained in the separation functional layer mainly has amino and carboxyl groups as terminal functional groups, and the degree of dissociation of these depends on pH. Under conditions of pH 3.0, the amino groups are mainly positively charged and the carboxyl groups are mainly neutral, so the zeta potential of the separation functional layer at pH 3.0 is thought to depend mainly on the amount of amino groups. Since R1 in general formula (I) is introduced in a way that modifies the amino groups, the amount of amino groups decreases as the amount of R1 introduced increases. Since the amount of amino groups is reflected in the zeta potential at pH 3.0, the zeta potential of the separation functional layer at pH 3.0 can be controlled by the amount of R1 introduced in the above general formula (I). That is, if the zeta potential of the separation functional layer at pH 3.0 is 10.0 mV or less, R1 has been sufficiently introduced into the separation functional layer, and the salt removal rate will be further improved. On the other hand, if the zeta potential at pH 3.0 is -15.0 mV or higher, the decrease in water production due to the excessive introduction of R1 can be suppressed. The zeta potential can be controlled, for example, by the conditions of step (b1) described in "(2-3) Modification of the separation functional layer" below.

[0088] (2) Method for producing a composite semipermeable membrane The method for manufacturing the composite semipermeable membrane according to this embodiment is not particularly limited as long as a composite semipermeable membrane satisfying the desired characteristics described above can be obtained, but for example, it can be manufactured by the following method.

[0089] (2-1) Formation of the support film For the method of forming the support film, known methods can be suitably used. The following description will take the case where PSf is used as the material for the porous support layer as an example.

[0090] First, PSf is dissolved in a suitable solvent to prepare a porous support layer stock solution. For example, N,N-dimethylformamide (hereinafter referred to as "DMF") is preferred as a suitable solvent for PSf.

[0091] The PSf concentration in the porous support layer stock solution is preferably 12% to 25% by mass, and more preferably 14% to 23% by mass. The higher the polymer concentration (i.e., solid content concentration) in the porous support layer stock solution, the higher the number density of particles on the surface of the porous support layer that can be obtained. As a result, the number density of protrusions in the separation function layer also increases, enabling the realization of a protrusion structure that can withstand pressure fluctuations. Furthermore, by lowering the polymer concentration, the surface pore diameter of the porous support layer is adjusted to such an extent that the monomer supply rate during separation function layer formation does not become too low, and protrusions with appropriate height are formed during separation function layer formation. When the PSf concentration in the porous support layer stock solution is within the above range, both the strength and water permeability of the resulting porous support layer can be achieved. The preferred range of polymer concentration in the porous support layer stock solution can be appropriately adjusted depending on the materials used, good solvents, etc.

[0092] Next, the obtained porous support layer stock solution is applied to the substrate surface and immersed in a coagulation bath containing a non-solvent of PSf. Water is preferred as the non-solvent of PSf in the coagulation bath. By bringing the porous support layer stock solution applied to the substrate surface into contact with the coagulation bath containing a non-solvent of PSf, the porous support layer stock solution coagulates through non-solvent-induced phase separation, and a support film with a porous support layer formed on the substrate surface can be obtained. The coagulation bath may consist only of a non-solvent of PSf, or it may contain a good solvent for PSf to the extent that the porous support layer stock solution can coagulate. The obtained support film may be washed before the formation of the separation functional layer to remove any remaining solvent in the film.

[0093] (2-2) Fabrication of the separation function layer (2-2-1) Process for forming the separation functional layer Regarding the process of forming a separation functional layer containing aromatic polyamide, we will describe, as an example, a method in which a polyfunctional aromatic amine and a polyfunctional aromatic acid halide are polymerized on the support film obtained in "(2-1) Formation of support film" to form a separation functional layer containing aromatic polyamide. From the viewpoint of productivity and performance, interfacial polymerization is the most preferred polymerization method. The interfacial polymerization process will be described below.

[0094] The separation function layer formation step (a) includes step (a1) contacting a support film with an aqueous solution containing a polyfunctional aromatic amine (hereinafter referred to as "polyfunctional aromatic amine aqueous solution"), step (a2) contacting the support film that has been contacted with the polyfunctional aromatic amine aqueous solution with an organic solvent solution containing a polyfunctional aromatic acid halide (hereinafter referred to as "polyfunctional aromatic acid halide solution"), step (a3) ​​draining the polyfunctional aromatic acid halide solution after contact, and step (a4) washing the composite semipermeable membrane. Note that even before carrying out step (b1) or step (b2) described later, the layer containing aromatic polyamide may be referred to as the separation function layer. Furthermore, a composite membrane having a substrate, a porous support layer, and a layer containing aromatic polyamide may be referred to as a composite semipermeable membrane.

[0095] Examples of porous support layers, polyfunctional aromatic amines, and polyfunctional aromatic acid halides include those mentioned above, and the same applies to preferred materials. In particular, from the viewpoint of easily forming crosslinked aromatic polyamides, it is preferable to use m-PDA as the polyfunctional aromatic amine and TMC as the polyfunctional aromatic acid halide.

[0096] In step (a1), the concentration of the polyfunctional aromatic amine in the aqueous solution of the polyfunctional aromatic amine is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.5% by mass or more and 15% by mass or less. When the concentration of the polyfunctional aromatic amine is within the above range, sufficient solute removal performance and water permeability can be obtained. Two or more types of polyfunctional aromatic amines may be used.

[0097] In step (a1), it is preferable that the aqueous solution be brought into uniform and continuous contact with the support film. Specifically, examples include coating the support film with a polyfunctional aromatic amine aqueous solution, or immersing the support film in the aqueous solution. The contact time between the support film and the aqueous solution is preferably 1 second to 10 minutes, and more preferably 3 seconds to 3 minutes.

[0098] After the aqueous solution has come into contact with the support film, it is preferable to remove any remaining droplets from the film. Removing the liquid helps to suppress the occurrence of defects in the separation layer. Methods for removing the liquid include, for example, holding the support film vertically after contact with the aqueous solution to allow excess solution to flow naturally, or forcibly removing the liquid by blowing a stream of air such as nitrogen from an air nozzle. After removing the liquid, the film surface can also be dried to remove some of the water from the aqueous solution.

[0099] In step (a2), examples of polyfunctional aromatic acid halides include polyfunctional aromatic acid chlorides such as TMC, biphenyldicarboxylic acid dichloride, azobenzenedicarboxylic acid dichloride, terephthalic acid chloride, isophthalic acid chloride, naphthalenedicarboxylic acid chloride, and 2,5-franzicarboxylic acid chloride. These polyfunctional aromatic acid chlorides may be used individually or in combination of two or more.

[0100] The organic solvent is preferably immiscible with water, dissolves polyfunctional aromatic acid halides, does not damage the support film, and is inert to polyfunctional aromatic amines and polyfunctional aromatic acid halides. Examples of organic solvents include hydrocarbon compounds such as n-nonane, n-decane, n-undecane, n-dodecane, isooctane, isodecane, and isododecane, as well as mixed solvents thereof.

[0101] The concentration of the polyfunctional aromatic acid halide in the polyfunctional aromatic acid halide solution is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.02% by mass or more and 4% by mass or less, and even more preferably 0.03% by mass or more and 2% by mass or less. When the concentration of the polyfunctional aromatic acid halide is 0.01% by mass or more, polymerization can proceed at a sufficient reaction rate. On the other hand, when the concentration of the polyfunctional aromatic acid halide is 10% by mass or less, the occurrence of side reactions during polymerization can be suppressed.

[0102] The aqueous solutions of polyfunctional aromatic amines and polyfunctional aromatic acid halides may contain, if necessary, compounds such as surfactants, antioxidants, and metal salts, as long as they do not inhibit polymerization.

[0103] The method for contacting a polyfunctional aromatic acid halide solution with a support film that has been contacted with a polyfunctional aromatic amine aqueous solution can be carried out in the same manner as the method for contacting the polyfunctional aromatic amine aqueous solution with the support film.

[0104] In step (a2), it is preferable to further contact the support film, which has been contacted with an aqueous solution of polyfunctional aromatic amine, with a solution of polyfunctional aromatic acid halide, and then heat-treat the film. By promoting the reaction through heat treatment and increasing the molecular weight, it is possible to reduce low molecular weight components and suppress changes in performance during acid contact. In addition, the halogenated carbonyl group of the aromatic acid halide may hydrolyze due to the influence of additives and moisture, which may reduce the reactivity with the aromatic amine, but this decrease in reactivity can be compensated for by promoting the reaction through heat treatment. The heat treatment temperature of the film is preferably 50°C to 180°C, more preferably 60°C to 160°C, and even more preferably 80°C to 150°C. If the heating temperature is 180°C or lower, it is possible to suppress the decrease in water permeability due to the thickening of the separation functional layer.

[0105] In step (a3), the organic solvent is removed by draining the polyfunctional aromatic acid halide solution after the reaction. For example, the organic solvent can be removed by grasping the film vertically and allowing excess organic solvent to flow naturally, by blowing air with a fan to dry out the organic solvent, or by using a mixed fluid of water and air to remove excess organic solvent.

[0106] In step (a4), the composite semipermeable membrane is washed with hot water. Washing with hot water removes unreacted monomers and oligomers. The temperature of the hot water used for washing is preferably 40°C to 100°C, and more preferably 60°C to 100°C. By going through these steps (a1) to (a4), a separation functional layer containing an aromatic polyamide having the substructure of the general formula (IX) is formed.

[0107] (2-3) Modification process of the separation functional layer The method for producing a composite semipermeable membrane according to this embodiment is a method for producing a composite semipermeable membrane comprising a separation functional layer containing an aromatic polyamide on a porous support layer, and comprises steps (b1) and (b2).

[0108] Step (b1): A step of bringing the separation functional layer into contact with a processing solution containing at least one compound selected from the group consisting of compounds represented by the following general formulas (X), (XI), and (XII).

[0109] [ka]

[0110] In general formula (X), W1 is an oxygen atom, a sulfur atom, or NV (where N is a nitrogen atom), V is a hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms, which may be substituted, and Z1 is a single bond or an atomic group having 1 to 12 carbon atoms, which may be substituted. Furthermore, all functional groups contained in Z1 are neutral or positively charged groups. The explanation for the Z1 atomic group is the same as that given in general formula (II) above.

[0111] [ka]

[0112] In general formula (XI), W1 is an oxygen atom, a sulfur atom, or NV (where N is a nitrogen atom), V is a hydrogen atom or an aliphatic chain having 1 to 10 carbon atoms, which may be substituted, and Z1 is a single bond or an atomic group having 1 to 12 carbon atoms, which may be substituted. Furthermore, all functional groups in Z1 are neutral or positively charged groups. 10 This is a hydroxyl group, a chlorine atom, a bromine atom, or an iodine atom. The explanation for the Z1 atomic group is the same as that given in general formula (II) above.

[0113] [ka]

[0114] In general formula (XII), Z4 and Z5 are each independently a formyl group, an acetal group, a hemiaminal group, or an aminal group, n is an integer from 1 to 6, X1 and X2 in each repeating unit are each independently a carbon atom or a nitrogen atom, and the cis-trans isomers of the double bond between X1 and X2 are not limited. L1 and L2 in each repeating unit are each independently a hydrogen atom, a halogen atom, an optionally substituted C1-C6 hydrocarbon, or a lone pair of electrons, and L1 and L2 may be directly or indirectly bonded to form a cyclic structure, and the sum of the carbon numbers of all L1 and L2 is 12n or less.

[0115] Step (b2): A step of bringing the separation functional layer into contact with a processing solution containing nitrate ions and having a pH of 2 or lower.

[0116] The order of steps (b1) and (b2) is not important, and they may be performed simultaneously. In other words, the separation functional layer may be brought into contact with a treatment solution containing at least one compound selected from the group consisting of compounds represented by the general formulas (X), (XI), and (XII) above, and nitrate ions, with a pH of 2 or lower.

[0117] By performing step (b1), the terminal amino group of the aromatic polyamide represented by the above general formula (IX) is modified with the compound represented by the above general formula (X), general formula (XI), or general formula (XII), and the structure represented by the above general formula (I) is formed.

[0118] Examples of compounds represented by the above general formula (X) include aliphatic carboxylic acid anhydrides such as acetic anhydride, butyric anhydride, pentanoic anhydride, heptanoic anhydride, octanoic anhydride, nonanoic anhydride, decanoic anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, and stearic anhydride.

[0119] Examples of compounds represented by the above general formula (XI) include aliphatic carboxylic acids such as acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid; N-alkyl α-amino acids such as sarcosine, N-ethylglycine, N-propylglycine, N-methylalanine, N-methylserine, and N-methylphenylalanine; salts of these compounds; and acid halides.

[0120] Examples of compounds represented by the above general formula (XII) include malealdehyde, (2Z,4Z)-hexa-2,4-dienedial, o-phthalaldehyde, 3-methylphthalaldehyde, 4-bromophthalaldehyde, 3,4-diformylmethyl benzoate, benzene-1,2,4,5-tetracarbaldehyde, benzo[d][1,3]dioxol-4,5-dicarbaldehyde, naphthalene-2,3-dicarbaldehyde, [1,1'-biphenyl]-2,2'-dicarbaldehyde, and (Z)-1,1,4,4-tetracarbaldehyde. Tramethoxy-2-butene, (3Z,5Z)-2,7-dimethylocta-3,5-diene, 1,2-bis(dimethoxymethyl)benzene, 1,2-bis(dimethoxymethyl)-3-methylbenzene, 4-bromo-1,2-bis(dimethoxymethyl)benzene, 3,4-bis(dimethoxymethyl)methyl benzoate, 1,2,4,5-tetrakis(dimethoxymethyl)benzene, 4,5-bis(dimethoxymethyl)benzo[d][1,3]dioxol, 2,3-bis(dimethoxymethyl)naphthalene, 2,2'-bis Su(dimethoxymethyl)-1,1'-biphenyl, (Z)-1,2-di(1,3-dioxolan-2-yl)ethene, (1Z,3Z)-1,4-di(1,3-dioxolan-2-yl)-1,3-butadiene, 1,2-di(1,3-dioxolan-2-yl)benzene, 1,2-di(1,3-dioxolan-2-yl)-3-methylbenzene, 4-bromo-1,2-di(1,3-dioxolan-2-yl)benzene, 3,4-di(1,3-dioxolan-2-yl)methyl benzoate, 1,2,4,5-tetra(1 Examples include ,3-dioxolan-2-yl)benzene, 4,5-di(1,3-dioxolan-2-yl)benzo[d][1,3]dioxol, 2,3-di(1,3-dioxolan-2-yl)naphthalene, 2,2'-di(1,3-dioxolan-2-yl)-1,1'-biphenyl, 1,1'-(1,2-phenylene)bis(1-methoxy-N,N-dimethylmethaneamine), 1,2-bis(1,3-dimethylimidazolidined-2-yl)benzene, and (Z)-N-(2-oxoethyridine)formamide.

[0121] In general formula (XII), X1 and X2 are preferably carbon atoms, and Z4 and Z5 are preferably formyl groups. When X1 and X2 are carbon atoms and Z4 and Z5 are formyl groups, a structure represented by general formula (I) having the structure represented by general formula (IV) as R1 can be obtained without side reactions. Furthermore, n is preferably 1. When n is 1, a rigid 5-membered ring structure is obtained by the reaction. In addition, L1 and L2 preferably form an aromatic ring containing X1 and X2 as the backbone, and more preferably form a benzene ring. By L1 and L2 forming an aromatic ring containing X1 and X2 as the backbone, a rigid and chemically stable ring structure can be introduced into the separation functional layer, and the decrease in water permeability associated with the reaction can be suppressed.

[0122] To obtain the structure represented by the above general formula (IV), the bond between X1 and X2 in general formula (XII) must be a double bond. That is, the compound of general formula (XII) must have a structure in which X1 and X2, located at both ends of the double bond or at both ends of the π-conjugated system, react with an amino group, forming Z4 and Z5, respectively.

[0123] The treatment solution, which contains at least one compound selected from the group consisting of compounds represented by general formulas (X), (XI), and (XII), may be brought into contact with the separation functional layer as a solution in which the compound is dissolved in a solvent, or as a liquid in which the compound is molten. When the treatment solution is brought into contact with the separation functional layer as a solution, water is preferably used as the solvent. Furthermore, when the treatment solution is a solution, the appropriate reaction time depends on the concentration of the compound in the solution and the temperature. When using a solution containing the compound represented by general formula (X), the contact time with the solution is preferably 10 seconds to 30 minutes, more preferably 10 seconds to 10 minutes, and even more preferably 10 seconds to 2 minutes. The concentration of the compound in the solution is preferably 0.1 mmol / L to 10 mmol / L, and more preferably 0.1 mmol / L to 1 mmol / L. The temperature at which the solution is brought into contact with the compound is preferably 60°C to 100°C, and more preferably 80°C to 100°C. When using a solution containing a compound represented by general formula (XI) or general formula (XII), the contact time with the solution is preferably 10 seconds to 60 minutes, more preferably 10 seconds to 10 minutes, and even more preferably 10 seconds to 2 minutes. The concentration of the compound in the solution is preferably 10 mmol / L to 500 mmol / L, and more preferably 50 mmol / L to 250 mmol / L. The temperature at which the solution is brought into contact with the compound is preferably 0°C to 35°C, and more preferably 15°C to 30°C. When using a solvent, water or isopropyl alcohol may be used. By performing process (b1) under the conditions within the preferred range described above, the ratio G / F can be controlled to a preferred range.

[0124] In step (b1), the processing solution may contain a reaction accelerator. Examples of reaction accelerators include 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholinium chloride (DMT-MM).

[0125] When water is used as the solvent, the pH of the solution may be arbitrarily set using any acid or base. If the pH of the solution is greater than 2 or the solution does not contain nitrate ions, a separate step (b2) of contacting the solution with a solution containing nitrate ions and with a pH of 2 or less must be performed either before or after step (b1).

[0126] In step (b2), the concentration of nitrate ions is preferably 0.01 mol / L or more and 1 mol / L or less, and the pH is preferably 0 or more and 2 or less. Furthermore, the temperature at which the solution is brought into contact is preferably 20°C or more and 100°C or less, more preferably 40°C or more and 100°C or less, even more preferably 60°C or more and 100°C or less, and even more preferably 80°C or more and 100°C or less.

[0127] When the treatment solution is a solution, the appropriate reaction time depends on the concentration and temperature of the compound in the solution, but the reaction time is preferably 10 seconds to 30 minutes, more preferably 10 seconds to 10 minutes, and even more preferably 10 seconds to 2 minutes.

[0128] When the concentration, pH, temperature, and processing time of the solution containing nitrate ions are within the above range, an appropriate amount of the structure represented by general formula (VIII) is easily formed, and the ratio A / B, ratio D / C, and b on the surface of the separation functional layer side * This can be considered a desirable range.

[0129] Furthermore, after steps (b1) and (b2), various processes may be performed between steps (a), (b1), and (b2).

[0130] (3) Use of composite semipermeable membranes The composite semipermeable membrane according to this embodiment is preferably used as a spiral-type composite semipermeable membrane element, wound around a cylindrical water collection pipe with numerous holes, together with a water supply channel material such as a plastic net, a permeable water channel material such as tricot, and a film to enhance pressure resistance as needed. Furthermore, a composite semipermeable membrane module can be formed by connecting these elements in series or parallel and housing them in a pressure vessel.

[0131] Furthermore, the composite semipermeable membrane, composite semipermeable membrane element, and composite semipermeable membrane module described above can be combined with a pump to supply water to them, a device to pre-treat the supply water, etc., to constitute a fluid separation device. By using this fluid separation device, the supply water can be separated into permeate water such as drinking water and concentrated water that did not permeate the membrane, thereby obtaining water suitable for the purpose. In other words, the above-mentioned composite semipermeable membrane can be used in a water treatment system that separates supply water into concentrated water and fresh water using a composite semipermeable membrane element incorporating it.

[0132] Examples of feedwater treated by the composite semipermeable membrane according to this embodiment include liquid mixtures containing a total dissolved solids content (hereinafter referred to as "TDS") of 500 mg / L to 100 g / L, such as seawater, brine, and wastewater. Generally, TDS refers to the total dissolved solids content and is expressed as "mass / volume" or "mass ratio". According to the definition, TDS is calculated from the mass of the residue after evaporating a solution filtered through a 0.45 micron filter at a temperature of 39.5 to 40.5°C, but in this specification, it is calculated more simply by converting it from the practical salinity (S).

[0133] A higher operating pressure for the fluid separation device improves the solute removal rate. Considering the increased energy required for operation and the durability of the composite semipermeable membrane, the operating pressure when supplying feedwater to the composite semipermeable membrane is preferably between 0.5 MPa and 10 MPa. A high feedwater temperature reduces the solute removal rate, and a low feedwater temperature reduces the amount of water produced, so a feedwater temperature of 5°C to 45°C is preferable. Furthermore, if the pH of the feedwater is high, in the case of feedwater with high solute concentrations such as seawater, scale such as magnesium is more likely to form, and deterioration of the composite semipermeable membrane is a concern, so a neutral pH range for the feedwater is preferable.

[0134] The salt removal rate of the composite semipermeable membrane is preferably 99.88% or higher, more preferably 99.90% or higher, and even more preferably 99.92% or higher. The water production volume is 0.80 m³. 3 / m 2 / day or more 1.80m 3 / m 2 Preferably less than / day, and 0.86m 3 / m 2 / day or more 1.80m 3 / m 2 Less than / day is more preferable, 0.90m 3 / m 2 / day or more 1.80m 3 / m 2 Less than / day is even preferable. [Examples]

[0135] The present invention will be described below with reference to specific examples, but the present invention is not limited in any way by these examples.

[0136] The physical properties of the composite semipermeable membrane according to this embodiment were measured by the following method.

[0137] <Salt removal rate> Seawater (TDS concentration 3.5%) adjusted to a temperature of 25°C and pH 6.5 was supplied at an operating pressure of 5.5 MPa to obtain permeate. The salt removal rate was determined from the TDS of the obtained permeate using the following formula. Salt removal rate (%) = 100 × {1 - (TDS concentration in permeate water / TDS concentration in supply water)}

[0138] <Water production amount> The amount of permeate obtained under the conditions described in "Salt Removal Rate" above is converted to the permeability per square meter of membrane surface per day (cubic meters), and the amount of water produced (m³) is used as an indicator of permeability. 3 / m 2 This represents (day).

[0139] <xps> XPS was performed on the surface of the separation functional layer of a composite semipermeable membrane dried at room temperature under vacuum conditions. Measurements were taken at three different locations on the same membrane, and the number of nitrogen atoms derived from nitro groups and the total number of nitrogen atoms were calculated from each measurement result. The average value was used. Measurement device: SSX-100 (manufactured by SSI Corporation) Excitation X-rays: monochromatic Al Kα 1-line, 2-line (1486.6 eV) X-ray diameter: 0.2 mm X-ray output: 10kV 20mA Photoelectron escape angle: 90° Analysis method: Wide scan analysis The N1s peak obtained by XPS is attributed to the inner-shell electrons of nitrogen atoms. In the examples and comparative examples described later, the N1s peak is thought to consist of components derived from NC and components derived from NOx (x≧2), and the N1s peak was split into two components. The component derived from NC appears around 400 eV, and the component derived from NOx (x≧2) appears around 406 eV. The area ratio of these components was calculated, and the value was rounded to the second decimal place.

[0140] <tof-sims> The composite semipermeable membrane was immersed in ethanol for one day, the surface on the separation function layer side was washed with ultrapure water, and then the composite semipermeable membrane was washed again by immersion in ultrapure water for one day. The washed composite semipermeable membrane was dried in a vacuum dryer for 24 hours. The surface on the separation function layer side of the dried composite semipermeable membrane was analyzed under the following conditions. Measurement device: TOF.SIMS 5 (Manufactured by ION-TOF) Secondary ion polarity: positive or negative Mass range (m / z): 0~1500 Raster size: 300 μm Number of scans: 32 Pixel count (per side): 256 pixels Vacuum level measured (before sample introduction): 4 × 10 -7 Pa or less Primary ion species: Bi3 ++ Primary ion acceleration voltage: 30kV Pulse width: 10.9 ns Bunching: Yes Neutralization of static charge: Yes Rear acceleration: 9.5kV

[0141] <Chromaticity measurement> After washing the composite semipermeable film with 90°C hot water for 2 minutes, the surface moisture was air-dried to obtain a film sample for chromaticity measurement. The dried composite semipermeable film was then measured on a black laboratory bench using a colorimeter (Konica Minolta CM-25d) in SCI mode, from the surface of the separation functional layer under the conditions of a measurement diameter of 8 mm, a 2° field of view, and a light source of D65. * a * b * Color space L * a * , b * The following was measured: Measurements were taken at 10 different locations on the same membrane, and the average value was taken as b * That's what I decided.

[0142] <Zeta potential> The composite semipermeable membrane was cut into 10cm x 10cm squares and washed with distilled water. The washed composite semipermeable membrane was set in a plate sample cell, and the separation functional layer was used as the measurement surface. The zeta potential of the separation functional layer at pH 3 was measured using an electrophoretic light scattering spectrometer ELSZneo (manufactured by Otsuka Electronics Co., Ltd.) under the following conditions. Five measurement points were randomly selected, and the average of these values ​​was taken as the zeta potential. Monitor particles: Polystyrene latex (hydroxypropyl cellulose coated) Measurement solution: NaCl aqueous solution (10mmol / L) pH: 3.0 Particle concentration: 0.1% by mass Average particle size: 500nm Temperature: 25℃ Light source: Charge-Ne laser

[0143] [Example 1] Polyester nonwoven fabric (air permeability 2.0 cc / cm²) 2 A support film was prepared by casting an 18.0 mass% DMF solution of PSf to a thickness of 200 μm onto the surface and immediately immersing it in pure water for 5 minutes. This support film was immersed in a 3.0 mass% m-PDA aqueous solution for 2 minutes. The support film was slowly lifted vertically, and excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In a controlled environment of 40°C, a 40°C n-decane solution containing 0.16 mass% TMC was applied to completely wet the surface. Next, the film was heated in a 120°C oven, and then the film was drained vertically to remove excess solution from the film. The resulting film was washed with 85°C hot water for 2 minutes to obtain composite semipermeable film A. The obtained composite semipermeable membrane was then immersed in a pH 1 nitric acid treatment solution at 85°C for 1 minute in step (b2), and then immersed in a pH 7 0.01% by mass aqueous solution of o-phthalaldehyde at 85°C for 1 minute in step (b1), and the membrane was washed with pure water to obtain a composite semipermeable membrane.

[0144] [Example 2] A composite semipermeable film was obtained in the same manner as in Example 1, except that the composite semipermeable film A was treated in the order of step (b1) and step (b2).

[0145] [Example 3] A composite semipermeable membrane was obtained in the same manner as in Example 2, except that instead of the pH 1 nitric acid in step (b2), a pH 1 treatment solution was used, which was obtained by mixing equal amounts of 0.5 mol / L sulfuric acid and 1 mol / L nitric acid and diluting it about 10 times with pure water.

[0146] [Example 4] A composite semipermeable membrane was obtained by immersing the membrane in a treatment solution containing 0.01% by mass of o-phthalaldehyde, adjusted to pH 1 using dilute nitric acid, at 85°C for 1 minute, performing steps (b1) and (b2) simultaneously, and then washing the membrane with pure water.

[0147] [Example 5] A composite semipermeable membrane was obtained by the same method as in Example 4, except that instead of dilute nitric acid, equal amounts of 0.5 mol / L sulfuric acid and 1 mol / L nitric acid were mixed and diluted approximately 10 times with pure water to adjust the pH of the treatment solution to 1.

[0148] [Example 6] A composite semipermeable film was obtained by the same method as in Example 1, except that o-phthalaldehyde in step (b1) was replaced with malealdehyde.

[0149] [Example 7] A composite semipermeable membrane was obtained by the same method as in Example 1, except that o-phthalaldehyde in step (b1) was replaced with 3-methylphthalaldehyde, and 10% by mass of isopropanol (hereinafter, "IPA") was added to the solution containing 3-methylphthalaldehyde.

[0150] [Example 8] A composite semipermeable film was obtained by the same method as in Example 1, except that o-phthalaldehyde in step (b1) was replaced with methyl 3,4-diformylbenzoate.

[0151] [Example 9] A composite semipermeable membrane was obtained by the same method as in Example 1, except that o-phthalaldehyde in step (b1) was replaced with benzo[d][1,3]dioxol-4,5-dicarboxylase.

[0152] [Example 10] A composite semipermeable film was obtained in the same manner as in Example 7, except that o-phthalaldehyde in step (b1) was replaced with naphthalene-2,3-dicarboxylaldehyde.

[0153] [Example 11] A composite semipermeable film was obtained in the same manner as in Example 7, except that o-phthalaldehyde in step (b1) was replaced with [1,1'-biphenyl]-2,2'-dicarboxylase.

[0154] [Example 12] A composite semipermeable membrane was obtained in the same manner as in Example 1, except that the pH in step (b2) was changed to 2.

[0155] [Example 13] A composite semipermeable film was obtained by the same method as in Example 1, except that the temperature in step (b1) was changed to 70°C.

[0156] [Example 14] A composite semipermeable film was obtained by the same method as in Example 1, except that the temperature in step (b1) was changed to 50°C.

[0157] [Example 15] A composite semipermeable membrane was obtained by the same method as in Example 1, except that the contact time in step (b2) was changed to 0.5 minutes, the processing solution in step (b1) was changed to a 1.0% by mass aqueous solution of anhydrous acetic acid, the temperature was changed to 25°C, and the immersion time was changed to 2 minutes.

[0158] [Example 16] A composite semipermeable membrane was obtained by the same method as in Example 1, except that the contact time in step (b2) was changed to 0.5 minutes, the processing solution in step (b1) was changed to an aqueous solution with pH 8, containing 0.9% by mass of sarcosine and 2.5% by mass of DMT-MM, the temperature was changed to 25°C, and the immersion time was changed to 60 minutes.

[0159] [Comparative Example 1] The composite semipermeable membrane A described in Example 1 was used as is.

[0160] [Comparative Example 2] In Example 1, the composite semipermeable membrane A was immersed in a pH 7, 0.1% by mass aqueous solution of o-phthalaldehyde for 60 minutes at 25°C as step (b1), and then the membrane was washed with pure water to obtain a composite semipermeable membrane.

[0161] [Comparative Example 3] A composite semipermeable membrane was obtained by the same method as in Comparative Example 2, except that the concentration of the processing solution in step (b1) was 0.01% by mass, the temperature was 85°C, and the immersion time of the composite semipermeable membrane in the processing solution was 1 minute.

[0162] [Comparative Example 4] A composite semipermeable membrane was obtained by the same method as in Example 1, except that step (b2) was replaced with immersion in sulfuric acid at pH 1 and 85°C for 1 minute.

[0163] [Comparative Example 5] On the surface of the composite semipermeable membrane A obtained in Example 1, a treatment solution of a pH 3, 3% by mass aqueous solution of potassium peroxymonosulfate was applied at 90°C at a rate of 0.33 L / m². 2 The film was applied in the specified ratio, covered with a film, and left to stand in the same oven used for application for 5 minutes. After that, it was immersed in a 0.1% by mass sodium bisulfite aqueous solution at 25°C for 10 minutes, and then the film was washed with pure water to obtain a composite semipermeable film. A structure was obtained in which the terminal amino groups of the aromatic polyamide were oxidized to nitro groups.

[0164] [Comparative Example 6] In Example 1, the composite semipermeable membrane A was immersed in a pH 1 nitric acid treatment solution at 85°C for 1 minute as step (b2), and then the membrane was washed with pure water to obtain a composite semipermeable membrane.

[0165] [Comparative Example 7] In Example 1, the composite semipermeable membrane A was immersed in a nitric acid treatment solution with a pH of 1 at 85°C for 1 minute as step (b2), then immersed in a 0.01% by mass aqueous solution of succinaldehyde with a pH of 7 at 85°C for 1 minute, and the membrane was washed with pure water to obtain a composite semipermeable membrane.

[0166] [Comparative Example 8] A composite semipermeable membrane was obtained using the same method as in Comparative Example 7, except that succinaldehyde was replaced with glutaraldehyde.

[0167] [Comparative Example 9] A composite semipermeable membrane was obtained using the same method as in Comparative Example 7, except that succinaldehyde was replaced with cyclopentane-1,3-dicarboxylaldehyde.

[0168] [Comparative Example 10] A composite semipermeable film was obtained by the same method as in Example 15, except that step (b2) was omitted.

[0169] [Comparative Example 11] A composite semipermeable film was obtained by the same method as in Example 16, except that step (b2) was omitted.

[0170] [Comparative Example 12] Polyester nonwoven fabric (air permeability 2.0 cc / cm²) 2 A support film was prepared by casting a 15.3% by mass DMF solution of PSf to a thickness of 200 μm onto the film and immediately immersing it in pure water for 5 minutes. This support film was then immersed in a 3.4% by mass m-PDA aqueous solution for 2 minutes. The support film was slowly lifted vertically, and excess aqueous solution was removed from the surface of the support film by blowing nitrogen from an air nozzle. In a controlled environment of 25°C, a 25°C n-decane solution containing 0.15% by mass TMC and 0.014% by mass oxalyl chloride was applied to the surface until it was completely wet, and it was left to stand for 1 minute. After that, the film was drained vertically to remove excess solution from the film. Subsequently, it was washed with 90°C hot water for 2 minutes and immersed in a sodium hypochlorite aqueous solution adjusted to pH 7, 25°C, and chlorine concentration of 200 mg / L for 2 minutes. Then, it was immersed in a 1000 mg / L sodium bisulfite aqueous solution to reduce and remove excess sodium hypochlorite. Furthermore, the membrane was washed again with hot water at 95°C for 2 minutes, immersed in a 0.1% by mass aqueous solution of o-phthalaldehyde at pH 7 at 25°C for 60 minutes, and then washed with pure water to obtain a composite semipermeable membrane.

[0171] [Comparative Example 13] A composite semipermeable membrane was obtained in the same manner as in Example 1, except that the pH in step (b2) was changed to 3.

[0172] The processing conditions for the examples and comparative examples are shown in Tables 1 and 2, and the results are shown in Tables 3 and 4. In the tables, "-" indicates that the result was below the detection limit.

[0173] [Table 1]

[0174] [Table 2]

[0175] [Table 3]

[0176] [Table 4]

[0177] The composite semipermeable membranes of Examples 1 to 16 according to this embodiment have a water production capacity of 0.80 m³. 3 / m 2 With a salt removal rate of over 99.88% per day, it is clear that it achieves both high water permeability and high salt removal performance.

[0178] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2025-032559, filed on 3 March 2025, the contents of which are incorporated herein by reference. < / xps>

Claims

1. A porous support layer, The porous support layer comprises a separation function layer provided on the porous support layer, The separation functional layer contains an aromatic polyamide having a structure represented by the following general formula (I), The aforementioned aromatic polyamide has a nitro group, A composite semipermeable film in which, in surface analysis of the separation functional layer side by X-ray photoelectron spectroscopy, the ratio A / B of the number of nitrogen atoms A derived from nitro groups to the total number of nitrogen atoms B is 0.002 or more and 0.100 or less. 【Chemistry 1】 [In general formula (I), Ar １ ~Ar ３ Each of these is an aromatic ring having 5 to 14 carbon atoms, which may be independently substituted, R １ The structure is represented by the following general formula (II) and / or the following general formula (III), R ２ ~R ４ Each of these is an aliphatic chain with 1 to 10 hydrogen atoms or, if substituted, carbon atoms. 【Chemistry 2】 【Transformation 3】 [In general formula (II) and general formula (III), W １ and W ２ are each independently an oxygen atom, a sulfur atom or NV (N is a nitrogen atom), and V is a hydrogen atom or an optionally substituted aliphatic chain having 1 to 10 carbon atoms. In general formula (II), Z １ is a single bond or an optionally substituted atomic group having 1 to 12 carbon atoms, Z ２ is an optionally substituted atomic group having 1 to 12 carbon atoms, and the sum of the carbon numbers of Z １ and Z ２ is 12 or less. In general formula (III), Z ３ is a single bond or an optionally substituted atomic group having 1 to 12 carbon atoms. In addition, all functional groups contained in Z １ to Z ３ are neutral groups or positively charged groups.]]

2. In the above general formula (I), R １ The above general formula (III) is where W ２ This is an oxygen atom, Z ３ The composite semipermeable membrane according to claim 1, wherein the structure is represented by the following general formula (IV). 【Chemistry 4】 [In general formula (IV), n is an integer from 1 to 6, and X in each repeating unit] １ , X ２ Each is independently a carbon atom or a nitrogen atom, X １ and X ２ The cis-trans isomers in the double bond are not limited. １ , L ２ Each is independently a hydrogen atom, a halogen atom, a substituted C1-C6 hydrocarbon, or a lone pair of electrons, L １ and L ２ They may be directly or indirectly connected to form a ring structure, and all L １ and L ２ The total number of carbon atoms is 12n or less.

3. The composite semipermeable membrane according to claim 2, wherein the aromatic polyamide includes a structure represented by the following general formula (VIII). 【Transformation 5】 [In general formula (VIII), Ar ４ ~Ar ６ Each of these is an aromatic ring having 5 to 14 carbon atoms, which may be independently substituted, R ５ ~R ９ Each of these is an aliphatic chain with 1 to 10 hydrogen atoms or, if substituted, carbon atoms.

4. The composite semipermeable membrane according to claim 2 or 3, wherein n in the general formula (IV) is 1 or more and 2 or less.

5. The composite semipermeable membrane according to claim 4, wherein the structure represented by the above general formula (III) is the structure represented by the following general formula (V). 【Transformation 6】 [In general formula (V), Y １ ~Y ４ Each of these is independently a hydrogen atom, a hydrocarbon having 1 to 4 carbon atoms which may be substituted, an ester group, or a halogen, Y １ ~Y ４ The total number of carbon atoms is 6 or less. １ ~Y ４ These may be directly or indirectly bonded to form a ring structure.

6. In the above general formula (V), Y １ ~Y ４ The composite semipermeable membrane according to claim 5, wherein is a hydrogen atom.

7. A composite semipermeable membrane according to any one of claims 1 to 3, wherein, in surface analysis of the separation functional layer by TOF-SIMS in negative secondary ion mode, the ratio D / C of the signal intensity D at m / z = 45.99 to the signal intensity C at m / z = 107.06 is 1.0 or more and 10 or less.

8. b when measured from the surface on the separation functional layer side. ＊ The composite semipermeable membrane according to claim 3, wherein the ratio is 1.5 or more and 20 or less.

9. In the surface analysis of the separation functional layer side by TOF-SIMS in positive second-order ion mode, the R in the general formula (I) with respect to the signal intensity F at m / z = 75.02 １ Among the fragments derived from the structure, the ratio G / F of the signal intensity G of the fragment with the highest signal intensity is 7.5 × 10 －３ The above 1.2 x 10 －１ The composite semipermeable membrane according to any one of claims 1 to 3, which is as follows:

10. A composite semipermeable membrane according to any one of claims 1 to 3, wherein the zeta potential of the surface on the separation functional layer side at pH 3.0 is -15.0 mV or more and 10.0 mV or less.

11. A composite semipermeable membrane element comprising a composite semipermeable membrane according to any one of claims 1 to 3.

12. A water treatment system for separating supply water into concentrated water and fresh water using a composite semipermeable membrane element as described in claim 11.

13. A method for producing a composite semipermeable membrane comprising a porous support layer and a separation functional layer containing an aromatic polyamide on the porous support layer, the method comprising the following steps (b1) and (b2). Step (b1): A step of bringing the separation functional layer into contact with a processing solution containing a compound represented by the following general formula (XII). Step (b2): A step of bringing the separation functional layer into contact with a processing solution containing nitrate ions and having a pH of 2 or lower. 【Transformation 7】 [In general formula (XII), Z ４ Z ５ Each is independently a formyl group, an acetal group, a hemiaminal group, or an aminal group, n is an integer from 1 to 6, and X in each repeating unit １ , X ２ Each is independently a carbon atom or a nitrogen atom, X １ and X ２ The cis-trans isomers in the double bond are not limited. １ , L ２ Each is independently a hydrogen atom, a halogen atom, a substituted C1-C6 hydrocarbon, or a lone pair of electrons, L １ and L ２ They may be directly or indirectly connected to form a ring structure, and all L １ and L ２ The total number of carbon atoms is 12n or less.

Images