JP2017023957A - Composite separation membrane and separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new composite separation membrane capable of suppressing deterioration of a rejection rate of dissolved matter other than humic acid such as salt contained in a liquid to be separated while improving a permeation flux.SOLUTION: A composite separation membrane according to the present invention comprises a porous support and a separation functional layer formed on the porous support. The separation functional layer is composed of a polyamide formed by a reaction of a compound group comprising an aliphatic polyfunctional amine, a linear hydrocarbon chain-containing polyfunctional amine, and a polyfunctional acid halide. The aliphatic polyfunctional amine has two or more secondary amino groups. The linear hydrocarbon chain-containing polyfunctional amine has a primary amino group bonded to one terminal of a linear hydrocarbon chain thereof and a primary amino group or a secondary amino group bonded to the other terminal of the linear hydrocarbon chain. The content of the linear hydrocarbon chain-containing polyfunctional amine in the polyfunctional amines in the compound group is less than 15 mol%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite separation membrane and a separation membrane element.

  A separation membrane that separates a liquid substrate (for example, water) from a dissolved material (for example, salts) is used for the production of pure water, desalination of brine such as seawater, and wastewater treatment. One type of separation membrane is a composite separation membrane comprising a porous support and a separation functional layer formed on the porous support. The separation functional layer is selected from organic compounds such as polyamide, polysulfone and cellulose acetate depending on the use of the composite separation membrane. As a composite separation membrane, a membrane composed of polyamide formed by a reaction between a polyfunctional amine and a polyfunctional acid halide is known.

  Currently, there is a demand for composite separation membranes with further improved separation characteristics. In particular, the size of the substrate flux (hereinafter simply referred to as “permeate flux”) is preferentially required over the rejection rate of dissolved substances, such as in wastewater treatment or pretreatment for seawater desalination. There is a strong demand to improve the separation characteristics to suit the application. In addition, there is always a demand for increasing the permeation flux of the composite separation membrane in order to reduce the operating energy of the apparatus (energy saving).

  Patent Documents 1 and 2 describe composite semipermeable membranes in which a separation functional layer of crosslinked polyamide is formed on a porous support membrane. In the composite semipermeable membrane described in Patent Document 1, the crosslinked polyamide is obtained by a reaction between a mixed amine component of an aliphatic polyfunctional amine and an aromatic polyfunctional amine, a polyfunctional acid halide, and a polyfunctional acid anhydride halide. can get. The molar ratio of polyfunctional acid halide to polyfunctional acid anhydride halide is in the range of 80/20 to 10/90.

  In the composite semipermeable membrane described in Patent Document 2, a separation functional layer of crosslinked polyamide is formed on a porous support membrane by polycondensation from a polyfunctional amine, a polyfunctional acid halide, and a polyfunctional acid anhydride halide. Yes. The polyfunctional amine is a mixed amine of an aliphatic polyfunctional amine and an aromatic polyfunctional amine.

JP 2000-33243 A JP 2000-202257 A

  The humic acid removal rate of the composite separation membrane described in Patent Documents 1 and 2 is high. However, when the composite separation membranes described in Patent Documents 1 and 2 are used without being used in combination with other separation membranes, they exhibit a high removal rate even for dissolved substances other than humic acids such as salts. I'm not sure if I can do it. Accordingly, one of the objects of the present invention is a composite separation membrane comprising a porous support and a separation functional layer formed on the porous support, and improves the permeation flux while being subject to separation. An object of the present invention is to provide a new composite separation membrane capable of suppressing a decrease in the blocking rate of dissolved substances other than humic acid such as a salt contained in a liquid.

The present invention
A porous support, and a separation functional layer formed on the porous support,
The separation functional layer includes an aliphatic polyfunctional amine having two or more secondary amino groups, a primary amino group bonded to an end of the linear hydrocarbon chain, and the other end of the linear hydrocarbon chain. A linear hydrocarbon chain-containing polyfunctional amine having a primary amino group or a secondary amino group, and a polyamide formed by the reaction of a compound group comprising a polyfunctional acid halide,
Provided is a composite separation membrane, wherein the ratio of the linear hydrocarbon chain-containing polyfunctional amine to the polyfunctional amine in the compound group is less than 15 mol%.

  Moreover, this invention provides the separation membrane element provided with said composite separation membrane.

  According to the present invention, a composite separation membrane comprising a porous support and a separation functional layer formed on the porous support, the salt contained in the separation target liquid while improving the permeation flux An object of the present invention is to provide a new composite separation membrane that can suppress a decrease in the blocking rate of dissolved substances other than humic acid.

It is a perspective view which shows typically an example of the separation membrane element of this invention.

  The composite separation membrane of the present invention comprises a porous support and a separation functional layer formed on the porous support. The separation functional layer is composed of a polyamide formed by the reaction of a compound group including an aliphatic polyfunctional amine (A), a linear hydrocarbon chain-containing polyfunctional amine (B), and a polyfunctional acid halide. The aliphatic polyfunctional amine (A) has two or more secondary amino groups. The polyfunctional amine (B) containing a linear hydrocarbon chain is composed of a primary amino group bonded to the end of the linear hydrocarbon chain and a primary amino group bonded to the other end of the linear hydrocarbon chain. Group or secondary amino group. The number of carbon atoms of the linear hydrocarbon chain of the linear hydrocarbon chain-containing polyfunctional amine (B) is, for example, 2 to 6. Here, the proportion of the linear hydrocarbon chain-containing polyfunctional amine (B) in the polyfunctional amine in the above compound group (hereinafter sometimes referred to as “ratio R”) is less than 15 mol%. “Primary amino group” means a monovalent functional group obtained by removing one hydrogen atom from a primary amine, and “secondary amino group” means that one hydrogen atom is removed from a secondary amine. Means a monovalent functional group.

  In this polyamide, each of the aliphatic polyfunctional amine (A) and the linear hydrocarbon chain-containing polyfunctional amine (B) reacts with the polyfunctional acid halide. Specifically, the polyamide has a structural unit formed by polymerization (polycondensation) of an aliphatic polyfunctional amine (A) and a linear hydrocarbon chain-containing polyfunctional amine (B). Therefore, the polyamide is composed of a structural unit (AU) formed by a reaction between an aliphatic polyfunctional amine (A) and a polyfunctional acid halide, a linear hydrocarbon chain-containing polyfunctional amine (B), and a polyfunctional acid halide. And a structural unit (BU) formed by the reaction with. Polyamide is a composite in which the permeation flux is improved while maintaining the rejection rate of the lysate contained in the liquid to be separated by including the structural unit (BU) in an appropriate molar ratio in addition to the structural unit (AU). A separation membrane is obtained. From this viewpoint, the ratio R is less than 15 mol%. Even when the ratio R is relatively small, it is possible to improve the permeation flux while maintaining the rejection rate of the dissolved matter contained in the separation target liquid. For this reason, the lower limit of the ratio R is not particularly limited, but is, for example, 0.1 mol% or more.

  The proportion of the aliphatic polyfunctional amine (A) in the polyfunctional amine in the compound group is greater than 85 mol%.

  The polyfunctional amine is an amine having two or more reactive amino groups, for example, a diamine having two reactive amino groups. The compound group may contain 2 or more types of aliphatic polyfunctional amines (A), and may contain 2 or more types of linear hydrocarbon chain-containing polyfunctional amines (B).

  Although an aliphatic polyfunctional amine (A) is not specifically limited, For example, it is an alicyclic polyfunctional amine. In this case, the combined flux with the linear hydrocarbon chain-containing polyfunctional amine (B) can improve the permeation flux of the composite separation membrane at a higher level.

  The aliphatic polyfunctional amine (A) is not particularly limited. For example, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, and a group consisting of piperazine and derivatives thereof It is at least 1 sort chosen from more. The aliphatic polyfunctional amine (A) is preferably piperazine or a piperazine derivative. In this case, the permeation flux can be improved more reliably while maintaining the rejection rate of the dissolved matter contained in the separation target liquid. Here, the piperazine derivative means a compound in which at least one hydrogen atom bonded to a carbon atom or a nitrogen atom of piperazine is substituted with a substituent. A substituent is a C1-C4 alkyl group, an amino group, and a hydroxyl group, for example. In addition, when the aliphatic polyfunctional amine (A) is a polyfunctional amine in which a hydrogen atom bonded to a nitrogen atom of piperazine is substituted, the substituent is an amino group. The piperazine derivative is, for example, at least one selected from 2,5-dimethylpiperazine and 4-aminomethylpiperazine.

  The linear hydrocarbon chain-containing polyfunctional amine (B) is desirably ethylenediamine or an ethylenediamine derivative. In other words, the linear hydrocarbon chain of the polyfunctional amine (B) containing the linear hydrocarbon chain has 2 carbon atoms. In this case, the permeation flux can be improved more reliably while maintaining the rejection rate of the dissolved matter contained in the separation target liquid. Here, the ethylenediamine derivative refers to a compound in which at least one hydrogen atom bonded to the nitrogen atom of ethylenediamine is substituted with a substituent. The substituent is, for example, an alkyl group having 1 to 4 carbon atoms or a phenyl group.

  The linear hydrocarbon chain-containing polyfunctional amine (B) is desirably at least one selected from the group consisting of N-phenylethylenediamine, N-methylethylenediamine, and ethylenediamine. In this case, the permeation flux can be improved more reliably while maintaining the rejection rate of the dissolved matter contained in the separation target liquid.

  The polyfunctional acid halide is an acid halide having two or more reactive carbonyl groups. The polyfunctional acid halide may be an aromatic polyfunctional acid halide or an aliphatic polyfunctional acid halide. The aliphatic polyfunctional acid halide may be an alicyclic polyfunctional acid halide. The compound group may contain two or more polyfunctional acid halides. When the compound group includes a polyfunctional acid halide having a valence of 3 or more, a separation functional layer composed of a polyamide having a crosslinked structure can be formed.

  The aromatic polyfunctional acid halide is not particularly limited, for example, trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyl dicarboxylic acid dichloride, naphthalene dicarboxylic acid dichloride, benzene trisulfonic acid trichloride, benzene disulfonic acid dichloride and It is at least one selected from the group consisting of chlorosulfonylbenzenedicarboxylic acid dichloride.

  The aliphatic polyfunctional acid halide is not particularly limited. For example, propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, butanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide. , Adipoyl halide, and at least one selected from the group consisting of alicyclic polyfunctional acid halides described below.

  The alicyclic polyfunctional acid halide is not particularly limited. For example, cyclopropanetricarboxylic acid trichloride, cyclobutanetetracarboxylic acid tetrachloride, cyclopentanetricarboxylic acid trichloride, cyclopentanetetracarboxylic acid tetrachloride, cyclohexanetricarboxylic acid trichloride, It is at least one selected from the group consisting of tetrahydrofurantetracarboxylic acid tetrachloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

  The structure of the porous support is not limited as long as the separation functional layer can be formed thereon. The porous support is, for example, an ultrafiltration membrane in which a microporous layer is formed on a nonwoven fabric. The average pore diameter of the microporous layer is, for example, about 0.01 to 0.4 μm. The material of the microporous layer is, for example, polyarylethersulfone such as polysulfone or polyethersulfone; polyimide; polyvinylidene fluoride. Of these, polysulfone and polyarylethersulfone are desirable because of their high chemical, mechanical and thermal stability. The porous support may be a self-supporting support composed of a thermosetting resin such as an epoxy resin. In this case, the porous support has an average pore diameter of, for example, 0.01 to 0.4 μm. Have The thickness of a porous support body is not specifically limited, For example, it is 10-200 micrometers, It is 20-75 micrometers desirably.

  The method for forming the separation functional layer on the porous support is not particularly limited, and a known method can be employed. Examples of the method for forming the separation functional layer include an interfacial condensation method, a phase separation method, and a thin film coating method. In the interfacial condensation method, an amine aqueous solution containing a polyfunctional amine is brought into contact with an acid halide organic solution containing a polyfunctional acid halide, so that the reaction between the polyfunctional amine and the polyfunctional acid halide at the contact surface (interface) ( This is a method for forming a separation functional layer composed of polyamide by advancing polycondensation). Formation of the separation functional layer by this interfacial condensation can be performed on the porous support, and in this case, the separation functional layer is directly formed on the porous support. Of course, a separation functional layer formed at a place other than on the porous support, for example, on the transfer substrate, may be placed on the porous support. Details of the interfacial condensation method are described, for example, in JP-A-58-24303 and JP-A-1-180208, and the conditions described in these known documents can be appropriately employed. Also in the phase separation method and the thin film coating method, methods described in known literatures can be employed.

  The separation functional layer is formed by applying an aqueous amine solution containing a polyfunctional amine component on a porous support to form an aqueous solution coating layer, and then applying an acid halide organic solution containing a polyfunctional acid halide to the porous support. It is desirable to make it contact with a coating layer and advance interfacial polymerization.

  In this method, the concentration of the polyfunctional amine in the aqueous amine solution is not particularly limited, and is, for example, 0.1 to 10% by weight, preferably 1 to 4% by weight. From the viewpoint of maintaining a high rejection rate of dissolved substances while preventing the occurrence of defects such as pinholes in the separation functional layer, the concentration of the polyfunctional amine in the aqueous amine solution is, for example, 0.1% by weight or more, preferably 1% by weight. Further, from the viewpoint of preventing the permeation resistance from being increased by preventing the permeation resistance from increasing due to the thickness of the separation functional layer being too large, the concentration of the polyfunctional amine in the aqueous amine solution is, for example, 10% by weight or less It is desirably 4% by weight or less.

  In this method, the concentration of the polyfunctional acid halide in the acid halide organic solution is not particularly limited, and is, for example, 0.01 to 5% by weight, desirably 0.05 to 3% by weight. Residual unreacted polyfunctional amines in the separation functional layer are suppressed, and defects such as pinholes are prevented from occurring in the separation functional layer, and from the viewpoint of maintaining a high rejection of dissolved substances, in the acid halide organic solution The concentration of the polyfunctional acid halide is, for example, 0.01% by weight or more, and desirably 0.05% by weight or more. Moreover, from the viewpoint of suppressing the decrease in the permeation flux by preventing the unreacted polyfunctional acid halide from remaining in the separation functional layer, avoiding an increase in the permeation resistance due to an excessive increase in the thickness of the separation functional layer, The concentration of the polyfunctional acid halide in the acid halide organic solution is, for example, 5% by weight or less, and desirably 3% by weight or less.

  The organic solvent used in the acid halide organic solution is not particularly limited as long as the solubility in water is low, the porous support is not deteriorated, and the polyfunctional acid halide is dissolved. For example, saturation such as cyclohexane, heptane, octane, nonane, etc. Hydrocarbon: Halogen-substituted hydrocarbon such as 1,1,2-trichlorotrifluoroethane. The organic solvent is preferably a saturated hydrocarbon having a boiling point of 300 ° C. or lower, and more preferably a saturated hydrocarbon having a boiling point of 200 ° C. or lower.

  The time from application of the aqueous amine solution to the application of the acid halide organic solution on the porous support depends on the composition and viscosity of the aqueous amine solution and the pore size of the surface of the porous support. About 2 to 120 seconds, more preferably 2 to 40 seconds, and particularly preferably 2 to 10 seconds. If the coating interval between the two is excessively long, the aqueous amine solution penetrates and diffuses deeply into the porous support before the acid halide organic solution is applied, so that the unreacted polyfunctional amine is porous supported. May remain in large quantities in the body. Moreover, the unreacted polyfunctional amine that has penetrated deep inside the porous support tends to be difficult to remove by subsequent washing treatment. On the other hand, if the coating interval between the two becomes excessively short, the aqueous amine solution hardly penetrates into the porous support until the application of the acid halide organic solution, and there is an excess aqueous amine solution on the porous support. The characteristics of the separated functional layer may be deteriorated.

  In this method, after contacting the coating layer of the aqueous amine solution formed on the porous support and the acid halide organic solution, the excess organic solution present on the porous support is removed and the porous support is removed. It is desirable to form the separation functional layer by heating and drying the film formed on the body. By mechanical drying, the mechanical strength and heat resistance of the separation functional layer can be increased. The temperature of heat drying is, for example, 70 to 200 ° C, and preferably 80 to 130 ° C. The heating time is, for example, about 30 seconds to 10 minutes, and preferably about 40 seconds to 7 minutes.

  In addition to the aliphatic polyfunctional amine (A), the linear hydrocarbon chain-containing polyfunctional amine (B), and the polyfunctional acid halide, the compound group facilitates the formation of a separation functional layer, Various additives can be included for the purpose of improving the properties. The additive may be included in, for example, an aqueous amine solution and / or an acid halide organic solution in the interfacial condensation method. Depending on the type of the additive, it remains in the formed separation functional layer, and contributes to, for example, improving the characteristics of the composite separation membrane.

  For example, the compound group further includes a hydrophilic polymer as an additive. The hydrophilic polymer is at least one selected from, for example, polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid, and polyvinyl alcohol is desirable. When the separation functional layer is formed by the interfacial condensation method, the polyfunctional amine aqueous solution may contain a hydrophilic polymer such as polyvinyl alcohol. The hydrophilic polymer is copolymerized with a polyfunctional amine and a polyfunctional acid halide to improve the hydrophilicity on the surface and inside of the formed separation functional layer. Thereby, the permeation flux of the composite separation membrane can be further improved. The addition amount of the additive is desirably about 0.01 to 20% by weight, and more desirably 0.05 to 5% by weight.

Other additives include, for example, surfactants such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and sodium lauryl sulfate that improve the wettability of the solution to the porous support; polyfunctional amines and polyfunctional acid halides Basic compounds such as sodium hydroxide, trisodium phosphate and triethylamine for removing hydrogen halide produced by the reaction; acylation catalyst as catalyst for the reaction; solubility parameter described in JP-A-8-224452 Is a compound of 8 to 14 (cal / cm ³ ) ^1/2 . These compounds may be added to the aqueous amine solution as necessary.

  For example, the additive is a salt of a tetraalkylammonium halide or trialkylammonium and an organic acid. This salt has effects such as making the separation functional layer easier to form, improving the absorbability of the aqueous amine solution to the porous support, and promoting the reaction between the polyfunctional amine and the polyfunctional acid halide. What is necessary is just to add this salt to amine aqueous solution as needed.

  The thickness of the separation functional layer is not particularly limited, and is usually about 0.05 to 2 μm, and preferably 0.1 to 1 μm. It is desirable that the separation functional layer has a uniform thickness.

  The shape of the separation functional layer is not particularly limited. One separation functional layer formed on the porous support may be used, or a separation functional layer having a “double pleated structure” described in JP-A-2011-189340 may be used.

  The separation functional layer is a layer made of polyamide. As long as the effect of the present invention is obtained, the separation functional layer may contain a material other than polyamide. At this time, the separation functional layer is a layer mainly composed of polyamide. The main component is a component having the largest content, and the content is usually 50% by weight or more, for example, 60% by weight or more, 70% by weight or more, 80% by weight or more, and 90% by weight or more. The separation functional layer may be a layer made of polyamide.

  The composite separation membrane of the present invention may be a membrane further subjected to chlorination. The permeation flux of the composite separation membrane is further improved by removing the unstable part of the polyamide in the chlorination. Moreover, in the composite separation membrane of this invention, the fall of the rejection rate of the melt | dissolution by chlorination is suppressed. The composite separation membrane of the present invention may be a membrane that has not been subjected to chlorination.

  A well-known method is employable for chlorination. For example, chlorination can be carried out by bringing an aqueous solution containing free chlorine into contact with the separation functional layer. The aqueous solution containing free chlorine is not particularly limited, and is, for example, an aqueous solution of a chlorine compound having an action of generating free chlorine in water such as sodium hypochlorite and calcium chloride. As for the density | concentration of the chlorine compound in the said aqueous solution, about 100-1000 mg / L is desirable, and the free chlorine density | concentration in that case is about 10-1000 ppm. The conditions for the chlorination are not particularly limited and can be controlled according to the free chlorine concentration of the aqueous solution, the material of the separation functional layer, etc. For example, the treatment time is controlled in the range of 10 minutes to 100 hours. The specific method for bringing the aqueous solution into contact with the separation functional layer is not particularly limited. For example, the composite separation membrane is immersed in the aqueous solution, the aqueous solution is applied or sprayed on the separation functional layer, or the aqueous solution is applied to the composite separation membrane. There is a way to let water through. When passing water, it is desirable to apply a pressure of about 1 to 5 MPa to the aqueous solution and pressurize the water.

  A coating layer may be provided on the surface of the composite separation membrane of the present invention. The coating layer is, for example, a nonionic hydrophilic layer and is a layer composed of a polymer. When the coating layer which is a hydrophilic layer is provided, the permeation flux of the composite separation membrane is further improved by improving the hydrophilicity of the composite separation membrane surface. The coating layer is desirably provided on the surface of the composite separation membrane on the separation functional layer side.

  The polymer used for the coating layer is not particularly limited as long as it does not dissolve the separation functional layer and the porous support and does not dissolve when the composite separation membrane is used (for example, during water treatment). The polymer is at least one selected from, for example, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl cellulose, polyethylene glycol, and a saponified ethylene-vinyl acetate copolymer. The polymer is preferably polyvinyl alcohol, and particularly preferably polyvinyl alcohol having a saponification degree of 99% or more. The coating layer can be formed on the surface of the composite separation membrane by, for example, immersing the composite separation membrane in a solution in which the polymer is dissolved and drying it.

  The coating layer may have a crosslinked structure with the polyamide constituting the separation functional layer. In this case, the elution of the coating layer when using the composite separation membrane can be suppressed. The coating layer having a crosslinked structure with polyamide is, for example, a layer containing polyvinyl alcohol having a saponification degree of 90% or more. The method for crosslinking polyvinyl alcohol and polyamide is not particularly limited. For example, a composite separation membrane in which a polyvinyl alcohol layer is formed on the surface of the separation functional layer may be immersed in a hydrochloric acid-containing polyvalent aldehyde solution. The polyvalent aldehyde is, for example, a dialdehyde such as glutaraldehyde or terephthalaldehyde. An organic crosslinking agent such as an epoxy compound and a polyvalent carboxylic acid and / or an inorganic crosslinking agent such as a boron compound may be used as a crosslinking agent instead of or together with the polyvalent aldehyde.

  The rejection rate (salt rejection rate) exhibited by the composite separation membrane of the present invention is a value at an operating pressure of 1.0 MPa with respect to an aqueous magnesium sulfate solution (concentration 0.20 wt%, pH 6.5, temperature 25 ° C.), for example, It is 98.5% or more, and can be 99.0% or more, 99.5% or more, and further 99.7% or more depending on the composition of the polyamide and the kind and amount of the additive.

The permeation flux exhibited by the composite separation membrane of the present invention is, for example, 1.00 (m ³ / (m ² · day)) or more when the operating pressure is 1.0 MPa, and the polyamide composition and additives 1.20 (m ³ / (m ² · day)) or more, 1.40 (m ³ / (m ² · day)) or more, 1.60 (m ³ / (m ² · day)) day)) or more, and further 1.80 (m ³ / (m ² · day)) or more. Also, the rejection rate can be achieved at the same time.

  For example, a separation membrane element is manufactured using the composite separation membrane of the present invention. As shown in FIG. 1, the separation membrane element 1 includes a composite separation membrane 31 that is a composite separation membrane of the present invention. The separation membrane element 1 is a spiral membrane element, and spirals around a central tube (water collecting tube) 35 in a state in which a composite separation membrane 31, a supply-side flow path member 32, and a permeate-side flow path member 33 are laminated. The laminated body 30 wound in the shape is provided. The separation membrane element 1 is manufactured, for example, by fixing the laminate 30 with an end member and an exterior material (both not shown). The separation membrane element 1 is used in a state where it is loaded in a pressure vessel (vessel) as necessary.

  The composite separation membrane of this invention can be used for the same use as the conventional composite separation membrane. The application is, for example, use as a reverse osmosis (RO) membrane, ultrafiltration (NF) membrane, microfiltration (MF) membrane, forward osmosis (FO) membrane. More specific applications include, for example, production of pure water or ultrapure water, desalination of brine such as seawater, removal of harmful components or recovery of useful components, concentration or recovery of active ingredients in the food or pharmaceutical field. It can be used for advanced processing.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to the Example shown below.

  First, a method for evaluating the composite separation membrane produced in this example is shown.

[Blocking rate]
The rejection rate (salt rejection rate) of the produced composite separation membrane was determined as follows. A magnesium sulfate (MgSO ₄ ) aqueous solution (concentration 0.20 wt%, temperature 25 ° C., pH 6.5) was permeated through the composite separation membrane at an operating pressure of 1.0 MPa for 30 minutes. Conductivity measurement of the membrane permeation liquid and the supply liquid was performed using a conductivity measuring device (Kyoto Denshi, CM-117), and based on the results and calibration curve (concentration-conductivity), MgSO ₄ The rejection rate was calculated.
Rejection = (1-(MgSO ₄ concentration of MgSO ₄ concentration / feed in the membrane permeate)) × 100 (%)

[Transmission flux]
The permeation flux of the produced composite separation membrane was determined by the following equation from the amount of membrane permeate measured together with the rejection rate.
Permeation flux (m ³ / (m ² · day)) = permeate volume / (membrane area × sampling time)

<Example 1>
Piperazine hexahydrate 0.998 wt%, N-phenylethylenediamine (PED) 0.002 wt%, sodium lauryl sulfate 0.15 wt%, sodium hydroxide 0.45 wt%, and polyvinyl alcohol (PVA) 0. An aqueous amine solution containing 25% by weight is applied to a porous polysulfone support membrane (an asymmetric membrane having an average pore size of 20 nm on the side where the separation functional layer is formed and an average pore size different on the opposite side). After application, excess aqueous solution was removed. The ratio of piperazine in the polyfunctional amine contained in the aqueous amine solution was 99.7 mol%, and the ratio of PED was 0.3 mol%. Next, an isooctane solution containing 0.9% by weight of trimesic acid chloride is brought into contact with the application surface of the aqueous amine solution on the porous support to advance the interfacial condensation polymerization reaction, and the separation function of the polyamide on the porous support is achieved. A composite separation membrane according to Example 1 was obtained by forming a layer (thickness: 1 μm). Note that the composite separation membrane according to Example 1 was not subjected to chlorine treatment.

The composite separation membrane according to Example 1 obtained in this way had a rejection rate (reception rate of MgSO ₄ ) of 99.9% and a permeation flux of 1.44 (m ³ / (m ² · day)). It was.

<Examples 2-7, Comparative Examples 1-5>
Examples 2 to 7 and Comparative Examples 1 to 5 were the same as Example 1 except that the ratio of piperazine and PED in the polyfunctional amine contained in the aqueous amine solution (monomer charge ratio) was changed as shown in Table 1. A composite separation membrane according to each of the above was prepared. The rejection rate and permeation flux of the obtained composite separation membrane are shown in Table 1 below together with the results of Example 1. In Comparative Example 5, the permeate could not be recovered.

As shown in Table 1, in Examples 1 to 7, the permeation flux was improved while maintaining the rejection rate of MgSO ₄ as compared with the comparative example.

<Examples 8 to 13 and Comparative Examples 6 to 9>
Example 1 except that N-methylethylenediamine (MED) was used instead of PED, and the ratio (monomer charge ratio) of piperazine and MED in the polyfunctional amine contained in the aqueous amine solution was adjusted as shown in Table 2. A composite separation membrane was prepared in the same manner as described above. The rejection rate and permeation flux of MgSO ₄ of the obtained composite separation membrane are shown in Table 2 below. In Table 2, Comparative Example 1 is shown again for reference.

  As shown in Table 2, in Examples 8 to 13, the permeation flux was improved while maintaining the blocking rate as compared with the comparative example.

<Examples 14-18, Comparative Examples 10-13>
Except that ethylenediamine (EDA) was used instead of PED, and the ratio of piperazine and EDA (monomer charge ratio) in the polyfunctional amine contained in the aqueous amine solution was adjusted as shown in Table 3, the same as in Example 1. Thus, a composite separation membrane was produced. The rejection rate and permeation flux of MgSO ₄ of the obtained composite separation membrane are shown in Table 3 below. In Table 3, Comparative Example 1 is shown again for reference.

As shown in Table 3, in Examples 14 to 18, the permeation flux was improved while maintaining the rejection rate of MgSO ₄ as compared with the comparative example.

30 Laminate 31 Composite Separation Membrane 32 Supply Side Channel Material 33 Permeation Side Channel Material 35 Center Pipe (Water Collection Pipe)

Claims (8)

A porous support, and a separation functional layer formed on the porous support,
The separation functional layer includes an aliphatic polyfunctional amine having two or more secondary amino groups, a primary amino group bonded to an end of the linear hydrocarbon chain, and the other end of the linear hydrocarbon chain. A linear hydrocarbon chain-containing polyfunctional amine having a primary amino group or a secondary amino group, and a polyamide formed by the reaction of a compound group comprising a polyfunctional acid halide,
The composite separation membrane whose ratio of the said linear hydrocarbon chain containing polyfunctional amine to the polyfunctional amine in the said compound group is less than 15 mol%.   The composite separation membrane according to claim 1, wherein the aliphatic polyfunctional amine is an alicyclic polyfunctional amine.   The composite separation membrane according to claim 1, wherein the aliphatic polyfunctional amine is piperazine or a piperazine derivative.   The composite separation membrane according to any one of claims 1 to 3, wherein the linear hydrocarbon chain-containing polyfunctional amine is ethylenediamine or an ethylenediamine derivative.   The composite according to any one of claims 1 to 4, wherein the linear hydrocarbon chain-containing polyfunctional amine is at least one selected from the group consisting of N-phenylethylenediamine, N-methylethylenediamine, and ethylenediamine. Separation membrane.   The composite separation membrane according to claim 1, wherein the compound group further includes a hydrophilic polymer.   The composite separation membrane according to claim 6, wherein the hydrophilic polymer is polyvinyl alcohol.   A separation membrane element comprising the composite separation membrane according to claim 1.

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