JP3489913B2 - High permeability composite reverse osmosis membrane - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite reverse osmosis membrane for selectively separating components in various liquid mixtures, and is also called an active layer or thin film containing a polyamide as a main component on a microporous support. The present invention relates to a composite reverse osmosis membrane having a skin layer, which has both high salt rejection and high permeability.

Such a composite reverse semipermeable membrane is preferably used for production of ultrapure water, which is indispensable for semiconductor production, desalination of seawater or brackish water, and particularly desalination of low-concentration inorganic salts,
It exhibits an excellent effect of eliminating cationic organic substances, and can obtain water of higher purity and recover waste water under low pressure operation which is energetically advantageous. Further, it can also be used for removal and recovery of pollution sources or effective substances that cause pollution from dyeing wastewater, electrodeposition paint wastewater and the like, and concentration of active ingredients in food applications and the like.

[0003]

2. Description of the Related Art Conventionally, a composite reverse osmosis membrane formed by forming an active skin layer having substantially selective separation on a microporous support as a reverse osmosis membrane having a structure different from that of an asymmetric reverse osmosis membrane. It has been known.

At present, many such composite reverse osmosis membranes are known in which a skin layer made of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide is provided on a support. (For example,
JP-A-55-147106, JP-A-62-121
603, JP-A-63-218208, and JP-A-2-187135). It is also known that a skin layer made of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional alicyclic acid halide is provided on a support (JP-A-61-42308).
Issue).

[0005]

However, the composite reverse osmosis membranes proposed therein have high desalination performance and water permeation performance, but improve water permeation performance while maintaining higher desalination performance. It is desired from the viewpoints of reduction of operating cost and equipment cost and efficiency. Various additives and the like have been proposed to meet such demands (for example, Japanese Patent Laid-Open No. 63-12310), but the performance is improved to some extent, but it is still insufficient and a composite reverse having higher performance. A permeable membrane is required.

Further, a skin layer made of polyamide obtained by interfacial polymerization of the above-mentioned polyfunctional aromatic amine and polyfunctional aromatic acid halide or polyfunctional alicyclic acid halide is provided on a support. In the composite reverse osmosis membrane, because polyamide has a negative fixed charged group, it has a high anion exclusion rate but a low cation exclusion rate in the high pH range for desalting inorganic salts in the low concentration range. There is a problem. In order to solve such a problem, JP-A-62-266103 proposes a composite reverse osmosis membrane having an active layer surface coated with an organic polymer having a positive fixed charge group. Since the osmotic membrane mainly has an adsorption mechanism due to its manufacturing method, it has a drawback that its performance deteriorates when it is repeatedly used. Moreover, the recently developed technology is not satisfactory as the second stage membrane of the two-stage reverse osmosis treatment (RO) in the preceding stage of the ultrapure water desalination line in semiconductor manufacturing. That is, a negatively charged membrane having a high desalination rate is used in the first stage, and the permeated liquid is supplied in the second stage.
It was found that the desalination performance was not sufficiently expressed.

The present invention has been made in view of the above-mentioned conventional problems, and maintains a high salt rejection rate, has a high water permeation performance, and also desalinates an inorganic salt in a low concentration region, and a cationic system. An object is to provide a composite reverse osmosis membrane that is excellent in eliminating organic substances.

[0008]

In order to achieve the above object, the highly permeable composite reverse osmosis membrane of the present invention comprises a compound having two or more reactive amino groups and two or more reactive acid groups. In a composite reverse osmosis membrane comprising a negatively charged crosslinked polyamide skin layer composed of a polyfunctional acid halogen compound having a halide group and a microporous support supporting the same, the polyamide on the surface of the composite reverse osmosis membrane The specific surface area of the system skin layer is 3 or more, and the surface of the polyamide system skin layer is coated with a crosslinked layer of an organic polymer having a positively chargeable group.

The specific surface area of the polyamide-based skin layer on the surface of the composite reverse osmosis membrane described above is defined by the following equation. Specific surface area of skin layer = (surface area of skin layer) / (surface area of microporous support) The surface area of the skin layer here is the surface opposite to the surface in contact with the microporous support, that is, the supply. The surface area of the surface in contact with the liquid is shown, and the surface area of the microporous support is the surface area of the surface in contact with the skin layer.

These surface areas and specific surface areas can be generally obtained by a method for obtaining surface roughness. For example, a surface area measuring device, a specific area measuring device, a scanning electron microscope (SE)
M, FE-SEM), a transmission electron microscope (TEM), etc. can be used for the measurement. However, it suffices that the surface area and the specific surface area be obtained, and the measuring method is not limited to the above.

In the above structure, the crosslinked layer of the organic polymer having the positively chargeable group is an organic polymer in which a polymer having a quaternary ammonium group and a hydroxyl group is intramolecularly and / or intermolecularly crosslinked. It is preferable.

Further, in the above constitution, it is preferable that the crosslinked layer of the organic polymer having a positively chargeable group is an organic polymer obtained by crosslinking polyethyleneimine. Further, in the above structure, the thickness of the crosslinked layer of the organic polymer having the positively chargeable group is 10 angstrom (1 nm) or more and 10 or more.
It is preferably in the range of μm or less.

The highly permeable composite reverse osmosis membrane of the present invention having the above structure is preferably used as a reverse osmosis membrane in the second and subsequent membrane modules of a multi-stage reverse osmosis treatment apparatus.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The highly permeable composite reverse osmosis membrane of the present invention comprises a compound having two or more reactive amino groups and a polyfunctional acid having two or more reactive acid halide groups. In a composite reverse osmosis membrane comprising a negatively charged crosslinked polyamide skin layer composed of a halogen compound and a microporous support supporting the same, the specific surface area of the skin layer on the surface of the composite reverse osmosis membrane is 3 or more. Moreover, by coating the surface of the skin layer with a cross-linking layer of an organic polymer having a positively chargeable group, it is excellent in desalting inorganic salts in a low concentration region and eliminating cationic organic substances, and has high water permeability. A composite reverse osmosis membrane having both properties can be realized. That is, the present inventors have found that there is a close relationship between the permeation flux and the specific surface area of the composite reverse osmosis membrane, and by regulating the specific surface area of the base membrane, provision of a positively charged layer is sufficient. It was found that an extremely high permeation flux can be obtained, and the present invention has been completed. In the present invention, in particular, the specific surface area of the polyamide-based skin layer on the surface of the composite reverse osmosis membrane is 3 or more and 1000 or more.
It is preferably the following or less, and more preferably 3.1 or more and 500 or less. If the specific surface area is less than 3, a sufficiently high permeation flux cannot be obtained, and if it exceeds 1000, the strength of the skin layer becomes small, so that the skin layer is easily damaged during use and is not practical. . Also,
When it is 3.1 or more and 500 or less, a highly permeable composite reverse osmosis membrane having sufficiently high permeation flux and sufficiently high skin layer strength can be realized.

The compound having two or more reactive amino groups used in the present invention is not particularly limited as long as it is a polyfunctional amine having two or more reactive amino groups, and aromatic, aliphatic, Alternatively, an alicyclic polyfunctional amine may be used.

Examples of such aromatic polyfunctional amines include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene and 8,5-diaminobenzoic acid. Acid, 2,4-diaminotoluene,
2,4-diaminoanisole, amidole, xylylenediamine and the like can be mentioned. As the aliphatic polyfunctional amine, for example, ethylenediamine, propylenediamine,
Examples include tris (2-aminoethyl) amine and the like. Further, as the alicyclic polyfunctional amine, for example, 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-
Diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine and the like can be mentioned.
These amines may be used alone or as a mixture.

The polyfunctional acid halide used in the present invention is not particularly limited, and examples thereof include aromatic, aliphatic, alicyclic and other polyfunctional acid halides. Examples of such aromatic polyfunctional acid halides include trimesic acid chloride, terephthalic acid chloride, isophthalic acid chloride, biphenyldicarboxylic acid chloride, naphthalenedicarboxylic acid dichloride, benzenetrisulfonic acid chloride, benzenedisulfonic acid chloride, chlorosulfonylbenzene. Examples thereof include dicarboxylic acid chloride.

Examples of the aliphatic polyfunctional acid halides include propane tricarboxylic acid chloride, butane tricarboxylic acid chloride, pentane tricarboxylic acid chloride, glutaryl halide and adipoyl halide.

Examples of the alicyclic polyfunctional acid halides include cyclopropane tricarboxylic acid chloride, cyclobutane tetracarboxylic acid chloride, cyclopentane tricarboxylic acid chloride, cyclopentane tetracarboxylic acid chloride, cyclohexane tricarboxylic acid chloride and tetrahydro. Furan tetracarboxylic acid chloride, cyclopentane dicarboxylic acid chloride, cyclobutane dicarboxylic acid chloride, cyclohexane dicarboxylic acid chloride, tetrahydrofurandicarboxylic acid chloride and the like can be mentioned.

In the present invention, the crosslinked polyamide is the main component on the microporous support by subjecting the compound component having two or more reactive amino groups and the acid halide component to an interfacial polymerization reaction. A composite reverse osmosis membrane having a thin film is obtained.

In the present invention, the microporous support for supporting the thin film is not particularly limited as long as it can support the thin film, and examples thereof include polysulfone, polyarylethersulfone such as polyethersulfone, polyimide, polyfluorine. Although various substances such as vinylidene chloride can be mentioned, in particular, since they are chemically, mechanically and thermally stable,
A microporous support membrane made of polysulfone or polyarylethersulfone is preferably used. Such microporous supports are typically about 25-125 μm, preferably about 4 μm.
Although it has a thickness of 0 to 75 μm, it is not necessarily limited thereto. More specifically, a first layer comprising a solution containing the amine component is formed on a microporous support, and then a layer comprising a solution containing the acid halide component is formed on the first layer. It can be obtained by forming and performing interfacial polycondensation to form a thin film of crosslinked polyamide on a microporous support.

The solution containing a polyfunctional amine is used for facilitating film formation or improving the performance of the obtained composite reverse osmosis membrane, for example, a polymer such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, or sorbitol. A small amount of a polyhydric alcohol such as glycerin can also be contained.

In order to increase the permeation flux, the solubility parameter is 8 to 14 (cal / cm ³ ) in the solution containing the polyfunctional amine and / or the solution containing the acid halide component.
^{One half} of the compound can be added.

Further, the amine salts described in JP-A-2-187135, such as salts of tetraalkylammonium halides and trialkylamines with organic acids, can also be added to the support of the amine solution to facilitate film formation. It is preferably used in terms of improving absorption, accelerating the condensation reaction, and the like.

Further, a surface active agent such as sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium lauryl sulfate can be contained. These surfactants are effective in improving the wettability of the solution containing the polyfunctional amine to the microporous support.

Further, in order to promote the polycondensation reaction at the interface, sodium hydroxide or trisodium phosphate capable of removing hydrogen halide produced in the interface reaction is used,
Alternatively, it is also beneficial to use an acylation catalyst or the like as the catalyst.

In the solution containing the acid halide and the solution containing the polyfunctional amine, the concentrations of the acid halide and the polyfunctional amine are not particularly limited, but the acid halide is usually 0.01 to 5 parts by weight. %, Preferably 0.0
5 to 1% by weight, and the polyfunctional amine is usually 0.1 to 1
It is 0% by weight, preferably 0.5 to 5% by weight.

In this way, after coating the solution containing the polyfunctional amine on the microporous support and then coating the solution containing the polyfunctional acid halide compound thereon, the excess solution is removed. Then, usually about 20-150
C., preferably about 70-130.degree. C. for about 1-10 minutes,
It is preferably dried by heating for about 2 to 8 minutes to form a water-permeable thin film (skin layer) made of crosslinked polyamide. The thickness of this thin film (skin layer) is usually about 0.05 to
It is in the range of 1 μm, preferably about 0.15 to 0.5 μm.

In the present invention, the surface of the negatively charged crosslinked polyamide-based skin layer must be coated with a crosslinked layer of an organic polymer having a positively chargeable group. If not coated, desalting of low-concentration inorganic salts and elimination of cationic organic substances cannot be sufficiently achieved.

The composite reverse osmosis membrane of the present invention may be one in which the surface of a negatively chargeable crosslinked polyamide skin layer is covered with a crosslinked layer of an organic polymer having a positively chargeable group. The structure of is not particularly limited.

However, in the present invention, workability,
From the viewpoint of processability, it is desirable that the organic polymer itself is soluble in a solvent, and therefore, one that is three-dimensionally crosslinked after being coated on the composite reverse osmosis membrane is preferable. As such an organic polymer, a polymer having a positively chargeable group and a functional group which causes a crosslinking reaction in the molecule, and a polymer which is itself soluble in a solvent is used. For example, as an example, a polymer having at least two hydroxyl groups and / or amino groups in a molecule together with a positively chargeable group (hereinafter referred to as polymer A), or at least two hydroxyl groups and / or amino in a molecule together with a positively chargeable group. Examples thereof include a polymer having a group and two protected isocyanate groups (hereinafter referred to as polymer B).

Here, examples of the positively chargeable group include an ammonium group, a phosphonium group and a sulfonium group. Further, the protected isocyanate group is an isocyanate group blocked using a blocking agent,
Alternatively, it refers to an isocyanate group protected in the form of an amine imide group.

Various blocking agents for blocking isocyanate groups are known, and examples thereof include phenols such as phenol and cresol, alcohols such as methanol, ethanol and methyl cellosolve, methyl ethyl ketoxime and acetaldehyde oxime. And oxime-based compounds such as

Examples of the polymer A include homopolymers of hydroxypropyltrimethylammonium chloride methacrylate and copolymers with other polymerizable monomers, and copolymers of ethyltrimethyltrimethylammonium chloride and hydroxyethyl methacrylate. Examples thereof include a polymer and a quaternized product of a copolymer of 4-vinylpyridine and hydroxyethyl methacrylate.

The polymer B is, for example, 2-
A copolymer of an isocyanate monomer obtained by blocking methacryloyloxyethylene isocyanate with an appropriate blocking agent and hydroxypropyl trimethyl ammonium chloride methacrylate, a copolymer of the above blocked isocyanate with 4-vinylpyridine and hydroxyethyl methacrylate. Polymer quaternary compounds, copolymers of vinyl monomers having an amine imide group such as 1,1-dimethyl-1- (2-hydroxypropyl) amine methacrylimide and hydroxypropyl trimethyl ammonium chloride methacrylate, etc. Can be mentioned.

The above polymers A and B are both soluble in water and alcohol. Therefore, in the present invention, the crosslinked polymer layer can be formed on the skin layer of the composite reverse osmosis membrane by various methods such as the following.

In order to form a crosslinked polymer layer obtained by crosslinking the polymer A, an aqueous solution or alcohol solution of the polymer A is applied to the composite reverse osmosis membrane and then dried to give polyisocyanate as a polyfunctional crosslinking agent. A solution in which the compound is dissolved is brought into contact with the polymer and heated as necessary to crosslink the polymer A between the molecules.

As another method, a polyfunctional polyisocyanate compound blocked with a blocking agent as described above is added to an aqueous solution or an alcohol solution of the polymer A,
After the obtained solution is applied to the composite reverse osmosis membrane, it may be heated to a temperature not lower than the dissociation temperature of the blocked polyisocyanate to liberate the polyisocyanate compound and to be cross-linked with the polymer A.

The polyisocyanate compound used here is not particularly limited, but examples thereof include tolylene diisocyanate and diphenylmethane diisocyanate, their multimers, isophorone diisocyanate, hexamethylene diisocyanate, triphenylmethane triisocyanate, tris (p). -Isocyanate phenyl) thiophosphite, an adduct of trimethylolpropane and tolylene diisocyanate, an adduct of trimethylolpropane and xylylene diisocyanate, and the like can be mentioned.

To form the crosslinked polymer layer of the polymer B on the composite reverse osmosis membrane, for example, a water or alcohol solution of the polymer B is applied on the composite reverse osmosis membrane to dissociate the blocked isocyanate. It may be heated at a temperature higher than the temperature to liberate the isocyanate group and crosslink intermolecularly and / or intramolecularly.

In order to accelerate the above-mentioned crosslinking reaction between the isocyanate group and the hydroxyl group, in the crosslinking reaction,
If necessary, a catalyst such as a tertiary amine or an organic tin compound can be used.

Further, in the present invention, as the cross-linked layer of the organic polymer having the positively chargeable group, one obtained by cross-linking polyethyleneimine with a cross-linking agent is also preferably used. In this case, the desalting performance with respect to the low-concentration inorganic salt and the removing performance of the cationic organic substance can be stably maintained for a long period of time. Here, as the cross-linking agent, glyoxal, glutaraldehyde and the like can be mentioned, and glutaraldehyde is particularly preferably used from the viewpoint of molecular weight. The method of coating the surface of the negatively chargeable crosslinked polyamide-based skin layer with this crosslinked layer is not particularly limited, for example, after coating or impregnated with the aqueous solution of polyethyleneimine to the negatively chargeable crosslinked polyamide-based skin layer, It is possible to employ a method in which the polyethyleneimine is crosslinked with the above-mentioned crosslinking agent, or polyethyleneimine is added to the raw water while performing reverse osmosis treatment, followed by washing with water and then adding the crosslinking agent by the same method. In this case, the concentration of polyethyleneimine is usually 0.1 to 10% by weight, preferably 1 to 5% by weight, and
The concentration of the cross-linking agent is usually 0.01 to 10% by weight, preferably 1 to 5% by weight.

Even if the organic polymer does not have a crosslinkable functional group as described above, the composite reverse osmosis membrane is irradiated with an electron beam after being coated with a positively charged organic polymer. It is also possible to generate a radical on the organic polymer skeleton and three-dimensionally crosslink it by a method of mixing a peroxide in the coalescence solution, coating the composite reverse osmosis membrane and then heating.

When polyethyleneimine is used as the organic polymer having the positively chargeable group and glutaraldehyde is used as the crosslinking agent, a polyethyleneimine crosslinked layer is formed by the reaction represented by the following formula (Formula 1).

[0045]

[Chemical 1]

The average molecular weight of polyethyleneimine used in the above is preferably 300 or more, more preferably 500 or more. In the present invention, the thickness of the crosslinked polymer layer thus formed is usually preferably in the range of 10 Å (1 nm) to 10 μm. 10
When the thickness is less than angstrom (1 nm), salt removal performance is hardly improved even when the obtained composite reverse osmosis membrane is used in a two-stage reverse osmosis system, while when it exceeds 10 μm, the water permeability of the obtained membrane is increased. This is not preferable because the performance is significantly reduced.

[0047]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

FIG. 1 is an example of a multistage reverse osmosis treatment process used in the present invention. In FIG. 1, 1 is a supply line for stock solution (raw water) such as well water or industrial water, 2 is a stock solution tank for storing the stock solution (raw water), 3 is a stock solution tank 2 and a first liquid feed pump 4 A liquid feed line for connecting the first liquid feed pump 4 and the first-stage membrane module 10 to each other, 11 to a stock solution chamber of the first-stage membrane module 10, and 12 to permeate the same module. It is a liquid chamber. In the pre-stage of the stock solution (raw water) supply line 1, any pretreatment such as rough filtration and biological treatment may be performed. A reverse osmosis membrane exists between the stock solution chamber 11 and the permeate chamber 12 of the first-stage membrane module 10, and the first-stage reverse osmosis treatment is performed. The first-stage permeated liquid that has left the permeated liquid chamber 12 is sent to the liquid feeding line 6, and is temporarily received by an intermediate receiving tank or a retention means 7 such as a pipe header capable of retaining a fixed amount, and a second liquid transmission pump 8 is received. Then, the solution is passed through the solution sending line 9 to send the solution to the second-stage membrane module 20. The reverse osmosis membrane of the present invention exists between the stock solution chamber 21 and the permeate chamber 22 of the second-stage membrane module 20, and the second-stage reverse osmosis treatment is performed.
The second-stage permeated liquid (ultra pure water) that has left the permeated liquid chamber 22 is taken out from the take-out line 13. 31 is a pressure regulating valve provided at the outlet of the stock solution chamber 11 of the first stage membrane module 10;
Reference numeral 2 is a pressure regulating valve provided at the outlet of the stock solution chamber 21 of the second-stage membrane module 20, and the operating pressures of the stock solution chambers 11 and 21 are adjusted by the valves 31 and 32, respectively.

In the multi-stage reverse osmosis treatment process, as an example of the first stage membrane module 10, a compound having two or more reactive amino groups and two or more reactive acid halide groups are included. It is preferable to use a composite reverse osmosis membrane composed of a negatively charged crosslinked polyamide-based skin layer obtained by interfacial polycondensation of a polyfunctional acid halogen compound and a microporous support supporting the skin layer. Further, as the second-stage membrane module 20, a crosslinked polyamide skin layer composed of a compound having two or more reactive amino groups and a polyfunctional acid halogen compound having two or more reactive acid halide groups. And a microporous support for supporting the same, wherein the skin layer has a specific surface area of 3 or more, and the surface of the skin layer is coated with a cross-linking layer of an organic polymer having positive fixed charge groups. Use a permeable membrane.

Reference Example 1 Methylethylketoxime 29
g was dissolved in 50 g of benzene, and 2-methacryloyloxyethylene isocyanate 5 was added to this solution at a temperature of 25 ° C.
1.6g was added dropwise over about 40 minutes, and then at 45 ° C for 2
Stir for hours. The obtained reaction product was analyzed by proton NMR, and it was confirmed that it was a blocked product obtained by quantitatively adding methylethylketoxime to 2-methacryloyloxyethylene isocyanate.

Reference Example 2 16 g of hydroxypropyltrimethylammonium methacrylate methacrylate and 8 g of the blocked isocyanate compound obtained in Reference Example 1 were dissolved in 60 g of methanol, to which 0.4 g of azobisisobutyronitrile was added, 6 at 60 ° C under nitrogen gas atmosphere
After stirring for a time, a copolymer having a quaternary ammonium group was obtained.

Example 1 m-Phenylenediamine
An aqueous solution containing 3.0% by weight, sodium lauryl sulfate 0.15% by weight, triethylamine 3.0% by weight, camphorsulfonic acid 6.0% by weight, and isopropyl alcohol 5% by weight was brought into contact with the microporous polysulfone support membrane. Then, the excess solution was removed to form a layer of the above solution on the support film.

Then, an IP1016 (isoparaffin hydrocarbons manufactured by Idemitsu Chemical Co., Ltd.) solution containing 0.20% by weight of trimesic acid chloride and 0.05% by weight of isopropyl alcohol was brought into contact with the surface of the supporting membrane,
Then, it was kept in a hot air drier at 120 ° C. for 3 minutes to form a skin layer on the support membrane, and thus a composite reverse osmosis membrane was obtained.

The obtained composite reverse osmosis membrane was washed with water and dried,
When the cross section of the composite reverse osmosis membrane was analyzed by TEM and the specific surface area of the polyamide-based skin layer was measured, the specific surface area was 4.3.

1 g of the copolymer obtained in Reference Example 2 was dissolved in water to prepare a 1% by weight aqueous solution. 1,4-azabicyclo (2,2,2) octane 0.008 as a crosslinking catalyst
5 g was added. The solution thus obtained is applied onto the above composite reverse osmosis membrane and heated at 150 ° C. for 10 minutes,
The copolymer was crosslinked to obtain a composite reverse osmosis membrane having positive charge (composite reverse osmosis membrane A).

Next, 2.0% by weight of m-phenylenediamine, 0.25% by weight of sodium lauryl sulfate, 2.0% by weight of triethylamine, camphorsulfonic acid.
An aqueous solution containing 4.0% by weight was brought into contact with the microporous polysulfone support membrane for several seconds to remove the excess solution to form a layer of the above solution on the support membrane.

Then, the IP1016 solution containing 0.10% by weight of trimesic acid chloride and 0.15% by weight of isophthalic acid chloride was brought into contact with the surface of the supporting film, and then in a hot air dryer at 120 ° C. for 3 minutes. By holding, a skin layer was formed on the support membrane to obtain a composite reverse osmosis membrane (composite reverse osmosis membrane B). The specific surface area of the skin layer of the obtained composite reverse osmosis membrane B was 2.2.

Next, using the process shown in FIG. 1, the composite reverse osmosis membrane B is used in the first stage, the composite reverse osmosis membrane A is used in the second stage, and well water having an electric conductivity of 100 μs / cm and a pH of 6.5 is used. Is used as a stock solution, and a solution that has permeated the composite reverse osmosis membrane B at an operating pressure of 30 kgf / cm ² is used as a supply solution.
When the membrane performance of the composite reverse osmosis membrane A was measured at / cm ² ,
The specific resistance is 9.5 MΩ · cm, and the permeation flux is 1.7 m ³ /
(M ² · day).

(Comparative Example 1) A composite reverse osmosis membrane C having a positive charge property was obtained in the same manner as in Example 1 based on the composite reverse osmosis membrane B (having the same surface shape as the conventional reverse osmosis membrane). . Similar to Example 1, when the composite reverse osmosis membrane B was used as the front stage and the composite reverse osmosis membrane C was used as the rear stage, the membrane performance was as follows: specific resistance value of 7.7 MΩ · cm and permeation flux of 0.9 m ³ / (M ²
・ Day) Compared with Example 1, the permeation flux was low and the specific resistance value was also low.

(Example 2) m-phenylenediamine
An aqueous solution containing 3.0% by weight, sodium lauryl sulfate 0.15% by weight, triethylamine 3.0% by weight, camphorsulfonic acid 6.0% by weight, and isopropyl alcohol 5% by weight was contacted with the microporous polysulfone support membrane. Then, the excess solution was removed to form a layer of the above solution on the support film. Then, on the surface of such a support film,
An IP1016 (isoparaffin hydrocarbon produced by Idemitsu Chemical Co., Ltd.) solution containing 0.20% by weight of trimesic acid chloride and 0.05% by weight of isopropyl alcohol was brought into contact, and then kept in a hot air dryer at 120 ° C. for 3 minutes. A skin layer was formed on the support membrane to obtain a composite reverse osmosis membrane.

The obtained composite reverse osmosis membrane was washed with water and dried, and then T
When the cross section of the composite reverse osmosis membrane was analyzed by EM and the specific surface area of the polyamide-based skin layer was measured, the specific surface area was 4.3.

Next, 1% by weight of polyethyleneimine was added to the pure water to be supplied and subjected to reverse osmosis treatment, followed by washing with wp water in the system, and then 1% by weight of glutaraldehyde was added to the pure water to be treated. Then, polyethyleneimine was crosslinked to obtain a composite reverse osmosis membrane having positive charge (composite reverse osmosis membrane D).

Next, 2.0% by weight of m-phenylenediamine, 0.25% by weight of sodium lauryl sulfate, 2.0% by weight of triethylamine, camphorsulfonic acid.
An aqueous solution containing 4.0% by weight was brought into contact with the microporous polysulfone support membrane for several seconds to remove the excess solution to form a layer of the above solution on the support membrane.

Then, the IP1016 solution containing 0.10% by weight of trimesic acid chloride and 0.15% by weight of isophthalic acid chloride was brought into contact with the surface of the supporting film, and then in a hot air dryer at 120 ° C. for 3 minutes. By holding, a skin layer was formed on the support membrane to obtain a composite reverse osmosis membrane (composite reverse osmosis membrane E). The specific surface area of the skin layer of the obtained composite reverse osmosis membrane B was 2.2.

Next, using the process shown in FIG. 1, the composite reverse osmosis membrane E is used in the first stage, the composite reverse osmosis membrane D is used in the second stage, and the well water having an electric conductivity of 100 μs / cm and a pH of 6.5 is used. Is used as a stock solution, and a liquid that has permeated the composite reverse osmosis membrane E at an operating pressure of 30 kgf / cm ² is used as a supply liquid.
When the membrane performance of the composite reverse osmosis membrane D was measured at / cm ² ,
The specific resistance is 9.9 MΩ · cm, and the permeation flux is 1.4 m ³ /
(M ² · day). In addition, 1000 in that state
When a continuous water flow test was conducted for 1,000 hours, the resistivity at the 1000th hour was 10.0 MΩ · cm, and the permeation velocity was 1.4 m.
^No decrease was observed as ³ / (m ² · day).

(Comparative Example 2) A composite reverse osmosis membrane F having a positive charge property was obtained in the same manner as in Example 2 based on the composite reverse osmosis membrane E (having the same surface shape as the conventional reverse osmosis membrane). . Similar to Example 2, when the composite reverse osmosis membrane E was used as the front stage and the composite reverse osmosis membrane F was used as the rear stage, the membrane performance was such that the specific resistance value was 7.7 MΩ · cm and the permeation flux was 0.9 m ³ / (M ²
・ Day) Compared with Example 1, the permeation flux was low and the specific resistance value was also low.

(Comparative Example 3) A composite reverse osmosis membrane G having a positive charge property was obtained in the same manner as in Example 2 except that the treatment with glutaraldehyde was not carried out. When the membrane performance was measured, the specific resistance value was 9.8 MΩ · cm and the permeation flux was 1.4 m ³ / (m ² · day). Also, 100
The specific resistance value at 0 hours was 5.3 MΩ · cm, and the permeation flux was 1.6 m ³ / (m ² · day), and the performance was deteriorated.

As described above, the composite reverse osmosis membrane obtained by the present invention is excellent in desalting an inorganic salt and eliminating a cationic organic matter in a low concentration region in a multi-stage reverse osmosis membrane system and the like, It was confirmed that both transparency and durability were obtained.

[0069]

As described above, the highly permeable composite reverse osmosis membrane according to the present invention comprises a compound having two or more reactive amino groups and two or more reactive acid halide groups. In a composite reverse osmosis membrane comprising a negatively charged crosslinked polyamide-based skin layer comprising a polyfunctional acid halogen compound having and a microporous support supporting the same, the polyamide-based skin layer on the surface of the composite reverse osmosis membrane Has a specific surface area of 3 or more, and the surface of the polyamide-based skin layer is coated with a cross-linking layer of an organic polymer having a positively chargeable group, so that a high salt rejection rate is maintained and high water permeation performance is obtained. In addition, there is an effect that it is possible to realize a composite reverse osmosis membrane which is excellent in desalting an inorganic salt in a low concentration region and eliminating a cationic organic substance.

[Brief description of drawings]

FIG. 1 is an example of a multi-stage reverse osmosis treatment process used in the present invention.

[Explanation of symbols]

1 Stock solution (raw water) supply line 2 stock solution tanks 3, 5, 6, 9 Liquid transfer line 4 First liquid delivery pump 7 Retention means 8 Second liquid delivery pump 10 First stage membrane module 11 Stock solution chamber of the first stage membrane module 12 Permeate chamber of the 1st stage module 13 Ultrapure water extraction line 20 First-stage membrane module 21 Second-stage module stock solution chamber 22 Permeate chamber of second stage module 31, 32 Regulator valve

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-5-92129 (JP, A) JP-A-62-266103 (JP, A) JP-A-4-200621 (JP, A) JP-A-9- 19685 (JP, A) JP-A-9-19630 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 61/00-71/82 510 C02F 1/44

Claims (5)

(57) [Claims] 1. A negatively chargeable crosslinked polyamide-based skin layer comprising a compound having two or more reactive amino groups and a polyfunctional acid halogen compound having two or more reactive acid halide groups. A composite reverse osmosis membrane comprising a microporous support for supporting the same, wherein the specific surface area of the polyamide-based skin layer on the surface of the composite reverse osmosis membrane is 3 or more, and the surface of the polyamide-based skin layer is positively charged. A highly permeable composite reverse osmosis membrane characterized by being coated with a cross-linked layer of an organic polymer having a group. 2. The crosslinked layer of an organic polymer having a positively chargeable group is an organic polymer in which a polymer having a quaternary ammonium group and a hydroxyl group is intramolecularly and / or intermolecularly crosslinked. High permeability composite reverse osmosis membrane. 3. The highly permeable composite reverse osmosis membrane according to claim 1, wherein the crosslinked layer of an organic polymer having a positively chargeable group is an organic polymer obtained by crosslinking polyethyleneimine. 4. The thickness of a crosslinked layer of an organic polymer having a positively chargeable group is 10 angstrom (1 nm) or more and 10 μm.
The highly permeable composite reverse osmosis membrane according to claim 1, which is in the following range. 5. The highly permeable composite reverse osmosis membrane according to claim 1, which is used as a reverse osmosis membrane in a membrane module of the second and subsequent stages of a multi-stage reverse osmosis treatment device.