WO2015114727A1

WO2015114727A1 - Composite separation membrane and separation membrane element using same

Info

Publication number: WO2015114727A1
Application number: PCT/JP2014/006510
Authority: WO
Inventors: 釜田　卓; 小原　知海
Original assignee: 日東電工株式会社
Priority date: 2014-01-28
Filing date: 2014-12-26
Publication date: 2015-08-06
Also published as: JP5961643B2; JP2015139742A

Abstract

This composite separation membrane is provided with a porous support and a separation function layer formed thereon. The separation function layer is made of a polyamide prepared by reaction of a group of compounds which comprise a polyfunctional amine having an aromatic ring, an aliphatic polyfunctional amine except the polyfunctional amine having an aromatic ring, and a polyfunctional acid halide. The units derived from the polyfunctional amine having an aromatic ring account for 30mol% or less of the polyfunctional amine units of the polyamide. The composite separation membrane is a composite separation membrane which is provided with both a porous support and a separation function layer formed thereon and which can achieve improvement in the permeation flux of the solvent of a liquid to be separated while inhibiting the rejection of solutes contained in the liquid from lowering.

Description

Composite separation membrane and separation membrane element using the same

The present invention relates to a composite separation membrane comprising a porous support and a separation functional layer formed thereon, and a separation membrane element comprising the composite separation membrane.

Separation membranes for separating a liquid substrate (for example, water) and a dissolved material (for example, salts) are used for 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, in recent years, the use of wastewater treatment or pretreatment for seawater desalination, in which the size of the substrate flux (hereinafter simply referred to as “permeate flux”) is preferentially required over the rejection rate of dissolved substances There is a strong demand to improve the separation characteristics to meet the requirements. 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 Document 1 describes a composite semipermeable membrane, which is a kind of composite separation membrane, having a separation functional layer mainly composed of a crosslinked polyamide.

JP 2008-246419 JP

In the composite separation membrane obtained by the method described in Patent Document 1, the permeation flow rate is still insufficiently improved, or the blocking rate of the dissolved product is excessively lowered. One of the objects of the present disclosure is a composite separation membrane including a porous support and a separation functional layer formed on the porous support, and a reduction in the blocking rate of the dissolved matter contained in the liquid to be separated The present invention provides a composite separation membrane with improved permeation flux while suppressing the above.

The composite separation membrane of the present disclosure includes a porous support and a separation functional layer formed on the porous support, and the separation functional layer includes a polyfunctional amine having an aromatic ring, and the polyfunctional Consists of a polyamide formed by the reaction of a compound group including an aliphatic polyfunctional amine excluding an amine and a polyfunctional acid halide, and is derived from the polyfunctional amine having the aromatic ring in the polyfunctional amine unit of the polyamide The proportion of units to be used is 30 mol% or less.

The separation membrane element of the present disclosure includes the composite separation membrane of the present disclosure.

According to the present disclosure, there is provided a composite separation membrane comprising a porous support and a separation functional layer formed on the porous support, which suppresses a decrease in the rejection rate of dissolved substances contained in the liquid to be separated. A composite separation membrane with improved permeation flux can be obtained.

It is a perspective view showing typically an example of a separation membrane element of this indication.

1st aspect of this indication is equipped with the porous support body and the separation functional layer formed on the said porous support body, The said separation functional layer is a polyfunctional amine which has an aromatic ring, The said polyfunctional amine It is composed of a polyamide formed by the reaction of a compound group including an aliphatic polyfunctional amine excluding and a polyfunctional acid halide, and is derived from the polyfunctional amine having the aromatic ring in the polyfunctional amine unit of the polyamide. A composite separation membrane having a unit ratio of 30 mol% or less is provided.

The second aspect of the present disclosure provides, in addition to the first aspect, a composite separation membrane in which the aliphatic polyfunctional amine is an alicyclic polyfunctional amine.

The third aspect of the present disclosure provides, in addition to the first aspect, a composite separation membrane in which the aliphatic polyfunctional amine is piperazine or a piperazine derivative.

In the fourth aspect of the present disclosure, in addition to any one of the first to third aspects, the polyfunctional amine having an aromatic ring is m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1, 3, 5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N-phenylethylenediamine, N, N′-dimethyl- Provided is a composite separation membrane that is at least one selected from m-phenylenediamine, 2,4-diaminoanisole, amidole, and xylylenediamine.

In the fifth aspect of the present disclosure, in addition to any one of the first to fourth aspects, the proportion of units derived from the polyfunctional amine having an aromatic ring in the polyfunctional amine units of the polyamide is 15 mol% or less. A composite separation membrane is provided.

The sixth aspect of the present disclosure provides a composite separation membrane in which the compound group further includes a hydrophilic polymer in addition to any one of the first to fifth aspects.

The seventh aspect of the present disclosure provides, in addition to the sixth aspect, a composite separation membrane in which the hydrophilic polymer is polyvinyl alcohol.

The eighth aspect of the present disclosure provides a composite separation membrane obtained by further subjecting the composite separation membrane of any of the first to seventh aspects to chlorination.

The ninth aspect of the present disclosure provides a separation membrane element using the composite separation membrane according to any one of the first to eighth aspects.

The composite separation membrane of the present disclosure includes a porous support and a separation functional layer formed on the porous support. The separation functional layer was formed by the reaction of a compound group including a polyfunctional amine (A) having an aromatic ring, an aliphatic polyfunctional amine (B) excluding the polyfunctional amine (A), and a polyfunctional acid halide. Consists of polyamide. This polyamide has, as a structural unit, a polyfunctional amine unit formed by reacting polyfunctional amines (A) and (B) with a polyfunctional acid halide, more specifically, polymerization (polycondensation). And the ratio (unit A) of the unit (unit A) derived from the polyfunctional amine (A) which has the said aromatic ring to all the polyfunctional amine units of this polyamide is 30 mol% or less.

A polyfunctional amine having an aromatic ring and an aliphatic polyfunctional amine (excluding amines having an aromatic ring; this “excluded” refers to amines that have an aromatic ring but are classified as aliphatic amines depending on the classification method. In other words, a polyfunctional amine having an aromatic ring is more reactive with a polyfunctional acid halide. That is, both amines have a difference in reactivity with polyfunctional acid halides. The difference in reactivity affects the structure of the formed polyamide membrane and the characteristics of the separation functional layer composed of the polyamide reflecting this structure. When the proportion of the unit A in the polyfunctional amine unit of the formed polyamide is 30 mol% or less, in the separation functional layer composed of the polyamide, there is a decrease in the blocking rate of the dissolved matter contained in the separation target liquid. The permeation flux is further improved while being suppressed. That is, a composite separation membrane in which the permeation flux is improved while the decrease in the rejection rate of the dissolved matter is suppressed is achieved.

When the proportion of the unit A in the polyfunctional amine unit of the polyamide exceeds 30 mol%, the polyfunctional amine unit does not contain the unit A in terms of the blocking rate of the lysate and / or the permeation flux in the composite separation membrane. Reduced compared to the case.

The proportion of unit A in the polyfunctional amine unit of the polyamide is preferably 20 mol% or less, and more preferably 15 mol% or less. Within these ranges, the effects of the present invention become more prominent. The lower limit of the ratio of the unit A is not particularly limited and is, for example, 0.1 mol% or more.

Among the polyfunctional amine units of the polyamide, the structural unit other than the unit A is a unit derived from a polyfunctional amine having no aromatic ring (unit B). The unit B is a unit derived from an aliphatic polyfunctional amine (B) other than the polyfunctional amine (A), for example. The proportion of unit B in the polyfunctional amine unit of the polyamide is 70 mol% or more, preferably 80 mol% or more, and more preferably 85 mol% or more.

Since the reactivity of the polyfunctional amine (A) having an aromatic ring with the polyfunctional acid halide is high, the monomer ratio of the polyfunctional amines (A) and (B) contained in the compound group before the reaction (charge ratio) ) Does not match the composition ratio of the polyfunctional amine units A and B in the polyamide formed by the reaction. In the formed polyamide, the proportion of units derived from the highly functional polyfunctional amine (A) is considerably larger than the value corresponding to the charging ratio. In other words, in the composite separation membrane of the present disclosure, by including a small amount of the polyfunctional amine (A) in the compound group, the permeation flux is improved at a higher level while suppressing a decrease in the blocking rate of the dissolved matter. The effect is gained.

The proportion of units A and B in the polyfunctional amine unit of the polyamide can be determined by a known composition analysis method for the polymer, for example, infrared spectroscopy (IR), ¹ H-nuclear magnetic resonance method ( ¹ H-NMR). it can.

A polyfunctional amine is an amine having two or more reactive amino groups. The compound group may contain 2 or more types of polyfunctional amines (A), and may contain 2 or more types of polyfunctional amines (B).

The polyfunctional amine (A) having an aromatic ring is not particularly limited, and examples thereof include m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-trimethyl. Aminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N-phenylethylenediamine, N, N'-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidol , And xylylenediamine. The polyfunctional amine (A) having an aromatic ring is more preferably at least one selected from m-phenylenediamine and N-phenylethylenediamine.

The aliphatic polyfunctional amine (B) is, for example, an alicyclic polyfunctional amine. An alicyclic polyfunctional amine is preferable from the viewpoint of improving the permeation flux at a higher level while suppressing a decrease in the blocking rate of the dissolved matter by combination with the polyfunctional amine (A).

The alicyclic polyfunctional amine is not particularly limited. For example, at least one selected from 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, and piperazine and derivatives thereof. It is. The alicyclic polyfunctional amine is preferably piperazine or a piperazine derivative. 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. Examples of the substituent include an alkyl group having 1 to 4 carbon atoms, an amino group, and a hydroxyl group. In addition, since it is a polyfunctional amine, when the hydrogen atom couple | bonded with the nitrogen atom is substituted, the said substituent is an amino group. The piperazine derivative is, for example, at least one selected from 2,5-dimethylpiperazine and 4-aminomethylpiperazine.

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, and examples thereof include 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 chloro. It is at least one selected from sulfonylbenzene dicarboxylic 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 alicyclic polyfunctional acid halide 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 tetrahydrofurantetracarboxylic acid tetrachloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride.

The configuration of the porous support is not limited as long as a 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 size 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 preferred 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 the porous support is not particularly limited and is, for example, 10 to 200 μm, preferably 20 to 75 μm.

The method for forming the separation functional layer on the porous support is not particularly limited, and a known method can be adopted. 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). The formation of the separation functional layer by the interfacial condensation can be performed on the porous support. 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 publicly-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 preferably formed by contacting with the coating layer and advancing interfacial polymerization.

In this method, the concentration of the polyfunctional amine in the amine aqueous solution is not particularly limited, and is, for example, 0.1 to 10% by weight, preferably 1 to 4% by weight. If the concentration of the polyfunctional amine in the aqueous amine solution is excessively low, defects such as pinholes are likely to occur in the formed separation functional layer, and the blocking rate of the dissolved product tends to decrease. On the other hand, when the concentration of the polyfunctional amine is excessively high, the thickness of the formed separation functional layer becomes too large, the permeation resistance increases, and the permeation flux tends to decrease.

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, preferably 0.05 to 3% by weight. If the concentration of the polyfunctional acid halide in the organic solution is excessively low, unreacted polyfunctional amines are likely to remain in the formed separation functional layer, and defects such as pinholes are likely to occur, and the blocking rate of dissolved substances. Tend to decrease. On the other hand, if the concentration of the polyfunctional acid halide is excessively high, unreacted polyfunctional acid halide tends to remain in the formed separation functional layer, or the thickness of the separation functional layer becomes too large and the permeation resistance increases. However, the permeation flux tends to decrease.

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, 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 is 1 to 180 seconds, depending 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 properties of the separated functional layer tend to 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 preferable to form a separation functional layer by heating and drying a film formed on the body. By mechanical drying, the mechanical strength and heat resistance of the separation functional layer can be increased. The temperature for heat drying is, for example, 70 to 200 ° C., 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 polyfunctional amines (A), (B) and polyfunctional acid halides, the compound group has various additions for the purpose of facilitating the formation of a separation functional membrane and improving the properties of the resulting composite separation membrane. An agent can be included. The additive may be contained in, for example, an aqueous amine solution and / or an acid halide organic solution in the interfacial condensation method. Depending on the type, the additive remains in the formed separation functional layer and contributes to, for example, improving the characteristics of the composite separation membrane.

The additive is, for example, a hydrophilic polymer. That is, the compound group may further contain a hydrophilic polymer. The hydrophilic polymer is, for example, at least one selected from polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid, and polyvinyl alcohol is preferable. 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 of the surface and inside of the formed separation functional layer. Thereby, the permeation flux of the composite separation membrane can be further improved. At the same time, in the composite separation membrane of the present disclosure characterized by the composition of the polyamide, the improvement in permeation flux by the hydrophilic polymer is larger than that of the conventional separation functional layer. The addition amount of the additive is preferably about 0.01 to 20% by weight, more preferably 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 catalysts for the reaction; solubility parameters 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 the following effects: makes it easier to form a separation functional layer; improves the absorbability of the aqueous amine solution to the porous support; promotes 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, preferably 0.1 to 1 μm. The thickness of the separation functional layer is preferably uniform.

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

The separation functional layer is composed of polyamide, that 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, and in the order of 60% by weight, 70% by weight, 80% by weight, 90% by weight or more. preferable. The separation functional layer may be 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.

The composite separation membrane of the present disclosure 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. At the same time, in the composite separation membrane of the present disclosure characterized by the composition of the polyamide, a decrease in the rejection rate of dissolved substances due to chlorination is suppressed as compared with the conventional separation functional layer.

Known methods can be employed 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. The concentration of the chlorine compound in the aqueous solution is preferably about 100 to 1000 mg / L, and the free chlorine concentration at that time is about 10 to 1000 ppm. The conditions for chlorination are not particularly limited and can be controlled according to the concentration of free chlorine in 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 of 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 preferable 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 disclosure. 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 preferably 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 elute when the composite separation membrane is used (for example, during water treatment). The polymer is, for example, at least one selected from polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl cellulose, polyethylene glycol, and a saponified ethylene-vinyl acetate copolymer. The polymer is preferably polyvinyl alcohol, 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 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 salt permeability exhibited by the composite separation membrane of the present disclosure is 95% or more as 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.). Depending on the composition of the polyamide, the presence or absence of chlorination, and the type and amount of the additive, it is 96% or more, 97% or more, 98% or more, and 99% or more.

The permeation flux shown by the composite separation membrane of the present disclosure is 1.5 (m ³ / (m ² · day)) or more when the operating pressure is 1.0 MPa. 1.8 (m ³ / (m ² · day)) or more, 1.9 (m ³ / (m ² · day)) or more, 2.0 (m ³ / (M ² · day)) or more, and further 3.0 (m ³ / (m ² · day)) or more. In addition, the salt permeability value can be achieved at the same time.

The composite separation membrane of the present disclosure is generally processed in the form of a separation membrane element and used in a state of being loaded in a pressure vessel (a vessel). For example, as shown in FIG. 1, the spiral membrane element is formed around a central pipe (water collecting pipe) 35 in a state where a composite separation membrane 31, a supply-side flow path member 32, and a permeate-side flow path member 33 are laminated. A laminate 30 wound in a spiral shape is provided. The membrane element is manufactured by fixing the laminate 30 with an end member and an exterior material.

The composite separation membrane of the present disclosure can be used for the same applications as conventional composite separation membranes. 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. The present invention is not limited to the examples shown below.

First, an evaluation method of the separation functional layer and the composite separation membrane produced in this example is shown.

[Polyamide composition]
The molar composition ratio of amine units in the polyamide constituting the separation functional layer (ratio of the proportion of each amine unit in the total amine units of the polyamide) is determined after mechanically separating the separation functional layer from the produced composite separation membrane. It was determined by performing ¹ H-NMR measurement on the separated functional layer.

[Salt rejection]
The salt rejection 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 permeate and the feed solution was performed using a conductivity measuring device (manufactured by Kyoto Electronics Co., Ltd., CM-117). From 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 from the amount of membrane permeate measured together with the salt rejection rate by the following formula.
Permeation flux (m ³ / (m ² · day)) = permeate volume / (membrane area × sampling time)

Example 1
An aqueous amine solution containing piperazine 3.582% by weight, m-phenylenediamine (MPD) 0.018% by weight, sodium lauryl sulfate 0.15% by weight, sodium hydroxide 0.45% by weight, and camphorsulfonic acid 6% by weight. After applying to a porous polysulfonic acid support, which is a porous support (an asymmetric membrane having an average pore diameter of 20 μm on the side where the separation functional layer is formed, and an average pore diameter on the opposite side is different), the excess aqueous solution is removed. did. Next, an isooctane solution containing 0.4% by weight of trimesic acid chloride is brought into contact with the application surface of the aqueous amine solution on the support to advance the interfacial condensation polymerization reaction. 1 μm) to form a composite separation membrane.

The composition ratio (molar ratio) of amine units in the separation functional layer of the composite separation membrane thus obtained was piperazine units: MPD units = 91: 9. The charging ratio was piperazine: MPD = 98: 2 in terms of molar ratio.

The resulting composite separation membrane had a salt (MgSO ₄ ) rejection of 99.7% and a permeation flux of 1.90 (m ³ / (m ² · day)).

(Examples 2 and 3, Comparative Examples 1 to 4)
A composite separation membrane was obtained in the same manner as in Example 1 except that the feed ratio of piperazine and MPD in the aqueous amine solution was controlled so as to have the values shown in Table 1 below.

Table 1 below shows the composition ratio of amine units, salt rejection, permeation flux, and the ratio of piperazine and MPD in the aqueous amine solution in the separation functional layers of Examples 1 to 3 and Comparative Examples 1 to 4. Since the composition ratio of amine units in the separation functional layer of Example 3 has not been measured at this stage, it is indicated by “−” in Table 1.

As shown in Table 1, in Examples 1 to 3, the permeation flux was significantly improved while suppressing the decrease in the salt rejection rate compared to Comparative Examples 2 and 3 with Comparative Examples 1 and 4 as a reference. .

(Example 4, Comparative Examples 5 and 6)
Except for using N-phenylethylenediamine (FED) instead of MPD and controlling the feed ratio of piperazine and FED in the aqueous amine solution so that the composition ratio of amine units in the separation functional layer is the value shown in Table 2 below. A composite separation membrane was obtained in the same manner as in Example 1.

Table 2 below shows the composition ratio, salt rejection and permeation flux of amine units in the separation functional layers of Example 4 and Comparative Examples 5 and 6.

As shown in Table 2, in Example 4, the same salt rejection and permeation flux as those in Example 2 in which the content of the polyfunctional amine unit (unit A) having an aromatic ring was almost the same could be achieved. Then, using Comparative Examples 1 and 4 as a reference, it was possible to achieve a significant improvement in permeation flux while suppressing a decrease in salt rejection compared to Comparative Examples 5 and 6.

(Examples 5 and 6, Comparative Examples 7 to 10)
The composite separation membranes prepared in Examples 1 and 2 and Comparative Examples 1 to 4 were immersed in an aqueous sodium hypochlorite solution having a free chlorine concentration of 100 mg / L for 72 hours to carry out chlorine treatment. 6 and Comparative Examples 7 to 10.

Table 3 below shows the composition ratio, salt rejection and permeation flux of amine units in the separation functional layers of Examples 5 and 6 and Comparative Examples 7 to 10.

As shown in Table 3, the permeation flux of Examples 5 and 6 was further improved compared to Examples 1 and 2 by chlorination.

(Example 7, Comparative Examples 11 and 12)
The composite separation membranes prepared in Example 4 and Comparative Examples 5 and 6 were subjected to chlorine treatment by immersing in a sodium hypochlorite aqueous solution having a free chlorine concentration of 100 mg / L for 72 hours. 11 and 12.

Table 4 below shows the composition ratio, salt rejection, and permeation flux of amine units in the separation functional layers of Example 7 and Comparative Examples 11 and 12.

As shown in Table 4, the permeation flux of Example 7 was further improved compared to Example 4 by chlorination. In Comparative Example 11, the salt rejection rate was greatly reduced and fell below 90%.

(Examples 8 to 12, Comparative Example 13)
While adding polyvinyl alcohol (saponification degree 99%) to the aqueous amine solution at a concentration of 0.25% by weight, piperazine and MPD in the aqueous amine solution so that the composition ratio of the amine units in the separation functional layer has the values shown in Table 5 below. A composite separation membrane was obtained in the same manner as in Example 1 except that the charging ratio was controlled.

(Examples 13 to 17, Comparative Example 14)
The composite separation membranes produced in Examples 8 to 12 and Comparative Example 13 were immersed in an aqueous sodium hypochlorite solution having a free chlorine concentration of 100 mg / L for 72 hours to perform chlorination, and Examples 13 to 17 and It was set as Comparative Example 14.

Table 5 below shows the composition ratio, salt rejection and permeation flux of amine units in the separation functional layers of Examples 8 to 17 and Comparative Examples 13 and 14. Examples 12 and 17 are composite separation membranes prepared with the same ratio of piperazine and MPD as in Example 3. The composition ratio of amine units in the separation functional layers of Examples 12 and 17 was not measured at this stage. Therefore, it is indicated by “−” in Table 5.

As shown in Table 5, by adding polyvinyl alcohol to the aqueous amine solution, the permeation flux could be further improved while suppressing a decrease in the salt rejection. Moreover, the permeation flux was further improved by chlorination.

The present invention can be applied to other embodiments without departing from the intent and essential features thereof. The embodiments disclosed in this specification are illustrative in all respects and are not limited thereto. The scope of the present invention is shown not by the above description but by the appended claims, and all modifications that fall within the meaning and scope equivalent to the claims are embraced therein.

Claims

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 including a polyfunctional amine having an aromatic ring, an aliphatic polyfunctional amine excluding the polyfunctional amine, and a polyfunctional acid halide,
The composite separation membrane whose ratio of the unit derived from the polyfunctional amine which has the said aromatic ring to the polyfunctional amine unit of the said polyamide is 30 mol% or less.
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 polyfunctional amine having an aromatic ring is m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diamino. Selected from benzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N-phenylethylenediamine, N, N′-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidole, and xylylenediamine The composite separation membrane according to claim 1, which is at least one kind.
The composite separation membrane according to claim 1, wherein the proportion of units derived from the polyfunctional amine having an aromatic ring in the polyfunctional amine units of the polyamide is 15 mol% or less.
The composite separation membrane according to claim 1, wherein the compound group further comprises a hydrophilic polymer.
The composite separation membrane according to claim 6, wherein the hydrophilic polymer is polyvinyl alcohol.
A composite separation membrane obtained by further chlorinating the composite separation membrane according to claim 1.
A separation membrane element using the composite separation membrane according to any one of claims 1 to 8.