JP2002095940A - Composite reverse osmosis membrane, method for manufacturing the same, and method for using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite reverse osmosis membrane excellent in desalting of inorganic salts and exclusion of cationic organic substances in their low concentration regions and having a high permeation flux, by chemically bonding an amine compound having at least four amino groups and 10 or more carbon atoms to a polyamide thin film produced by an interfacial polycondensation reaction and crosslinking reaction of a polyfunctional amine with a polyfunctional acid halide component. SOLUTION: A polyamide thin film produced by an interfacial polycondensation reaction and crosslinking reaction of m-phenylenediamine with trimesic acid chloride is further reacted with, for example, an amine compound represented by formula 1 to be chemically bonded to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composite reverse osmosis membrane for selectively permeating and separating components in a liquid mixture. It is particularly suitable for the production of ultrapure water, desalination of brackish water, etc.It also removes pollution sources or active substances contained in the pollutants such as factory drainage, dyeing drainage, electrodeposition paint drainage, etc. It can be removed and collected, contributing to the closing of wastewater.

[0002]

2. Description of the Related Art In recent years, various composite reverse osmosis membranes in which an active layer and a support layer for supporting the active layer are manufactured from different materials have been proposed. Because of its excellent performance, it is used in many fields.

However, the active layer of these composite reverse osmosis membranes is mainly composed of a crosslinked polyamide because of its ease of production, and has a negative fixed charge group. Regarding the desalting of inorganic salts, there is a problem that the rejection of the anion is high in the high pH range but the rejection of the cation is low, so that the rejection as a whole decreases. In order to solve such a problem, there has been proposed a composite reverse osmosis membrane in which an active layer surface is coated with an organic polymer having a positive fixed charge group (Japanese Patent Application Laid-Open No. 62-266103).

[0004]

However, the composite reverse osmosis membrane proposed in the above-mentioned conventional Japanese Patent Application Laid-Open No. 62-266103 mainly uses an adsorption mechanism because of its manufacturing method, so that it can be used repeatedly. In this case, it was insufficient in that the desired performance was sometimes reduced with some dropout. In particular, it is a recently developed technique and is not satisfactory as a second-stage membrane in a two-stage reverse osmosis treatment (RO) in a stage preceding a ultrapure water desalination line in semiconductor manufacturing. That is, it was found that a negative electrode membrane having a high desalination rate was used in the first stage, and the permeate was supplied in the second stage.

In order to solve the above-mentioned conventional problems, the present invention provides a composite reverse osmosis membrane having excellent desalting of inorganic salts in a low concentration region and elimination of cationic organic substances and having a high permeation flux. It is an object to provide a manufacturing method and a method for using the same.

[0006]

In order to achieve the above object, a composite reverse osmosis membrane according to the present invention is a composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the thin film. A polyamide thin film obtained by subjecting a functional amine component and a polyfunctional acid halide component to an interfacial polycondensation reaction and a crosslinking reaction, wherein the thin film is an amine compound having at least 4 amino groups and 10 or more carbon atoms. It is characterized in that the residues are chemically bonded.

The composite reverse osmosis membrane preferably has a positive zeta potential at the membrane surface at pH 6. Specifically, the surface of the thin film is cationic.

In the composite reverse osmosis membrane, an amine compound residue having at least 4 amino groups and 10 or more carbon atoms is represented by any of the above formulas (1) to (4). Is preferred. With these compound residues, the surface of the thin film can be maintained at a preferable cationic property.

In the composite reverse osmosis membrane, it is preferable that the thin film is composed of residues of an aromatic polyfunctional amine component and residues of an aromatic polyfunctional acid halide component.

Next, the method for producing a composite reverse osmosis membrane of the present invention is as follows.
A method for producing a composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the same, comprising: (a) an essentially simple reverse osmosis membrane having at least two amino groups selected from primary and secondary. A solution A containing a dimeric amine compound;
(B) a solution B containing an essentially monomeric acid halide compound having at least two or more acid halide groups,
(C) contacting, interfacial polycondensation reaction and cross-linking reaction to form a polyamide thin film, and (d) the thin film has at least four amino groups selected from primary and secondary and has carbon atoms. A solution containing an amine compound having 10 or more atoms is brought into contact with and chemically bonded.

In the above method, it is preferable that the amine compound having at least 4 amino groups and 10 or more carbon atoms is represented by any one of the above formulas (Chemical Formulas 5 to 8).

Next, the method of using the composite reverse osmosis membrane of the present invention is as follows.
The composite reverse osmosis membrane according to any one of the above is used in any one of the steps of multistage reverse osmosis membrane treatment.

[0013]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, the amine component contained in the solution A is an amine selected from the group of essentially monomeric amine compounds having at least two primary and / or secondary amino groups. It is not particularly limited as long as it is a polyfunctional amine containing at least one compound, and is aromatic, aliphatic,
Or an alicyclic polyfunctional amine is mentioned. Examples of such aromatic polyfunctional amine compounds include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene,
Examples thereof include 3,5-diaminobenzoic acid, 2,6-diaminotoluene, 2,4-diaminoanisole, and xylylenediamine. As the aliphatic polyfunctional amine compound, for example, ethylenediamine, propylenediamine,
Tris (2-aminoethyl) amine and the like can be mentioned. Examples of the alicyclic polyfunctional amine compound include, for example, 1,3
-Diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine and the like. These amines may be used alone or as a mixture.

In the present invention, the acid halide component contained in the solution B is an acid halide containing at least one selected from the group consisting of essentially monomeric acid halide compounds having at least two or more acid halide groups. If it is not particularly limited, examples thereof include aromatic, aliphatic, and alicyclic polyfunctional acid halides. Such aromatic polyfunctional acid halides include, for example, 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 and benzenehexacarboxylic acid halide. Examples of the aliphatic polyfunctional acid halide include propanetricarboxylic acid chloride, butanetricarboxylic acid chloride, pentanetricarboxylic acid chloride, glutaryl halide, and adipoyl halide. Examples of the alicyclic polyfunctional acid halide include, for example, cyclopropanetricarboxylic acid chloride, cyclobutanetetracarboxylic acid chloride, cyclopentanetricarboxylic acid chloride, cyclopentanetetracarboxylic acid chloride, cyclohexanetricarboxylic acid chloride, tetrahydrofurantetracarboxylic acid Acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, tetrahydrofurandicarboxylic acid chloride and the like.

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

In the present invention, the compound further has at least four primary and / or secondary amino groups and has one carbon atom.
It must be brought into contact with and reacted with a solution containing an amine component containing at least one selected from the group of amine compounds having zero or more amine compounds.

According to the present invention, at least 4
The amine compound having one or more primary and / or secondary amine groups and having 10 or more carbon atoms is not particularly limited, and examples thereof include compounds represented by the following formulas (Chemical Formulas 9 to 12). Is mentioned.

[0018]

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[0019]

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[0020]

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[0021]

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By reacting these amine compounds, the membrane surface becomes cationic. These amine compounds are free carboxylic acids (—COO) present in a polyamide thin film obtained by subjecting the polyfunctional amine component and the polyfunctional acid halide component to an interfacial polycondensation reaction and a crosslinking reaction.
H) to undergo a polycondensation reaction to form a covalent bond and / or to be fixed to the carboxylic acid or other carbonyl group by an ionic bond.

The microporous support used in the present invention comprises:
The material is not limited as long as it can support the thin film. Usually, the surface has a pore size of 10 to 500 angstroms (1 to 50 n).
An ultrafiltration membrane having pores of m) is used. For example, various materials such as polysulfone, polyether sulfone, polyimide, polyamide, polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, and cellulose acetate can be used. Particularly, an ultrafiltration membrane made of polysulfone, polyethersulfone, or the like is preferably used because it is chemically, mechanically, and thermally stable. Such an ultrafiltration membrane may be reinforced with a woven fabric, a nonwoven fabric, or the like.

In addition, salt damage caused by an amine salt described in JP-A-2-187135, for example, a tetraalkylammonium halide or a trialkylamine, and an organic acid also makes it easy to form a film. It is suitably used in terms of improving the properties and accelerating the condensation reaction.

The presence of a substance having a solubility parameter of 8 to 14 (cal / cm ³ ) ^1/2 described in JP-A-8-224452 in the crosslinking reaction is also effective in increasing the amount of permeated water. There is.

Further, a surfactant such as sodium dodecylbenzenesulfonate, sodium dodecyl sulfate and sodium lauryl sulfate can be combined. These surfactants are effective in improving the wettability of a polar solvent solution containing an amine component on a microporous support. Further, in order to promote the polycondensation reaction at the interface, use of sodium hydroxide or trisodium phosphate capable of removing hydrogen halide generated by the interface reaction, or use of an acylation catalyst or the like as a catalyst Is also desirable.

In the solution A containing the amine component, the concentration of the amine compound is not particularly limited, but is usually 0.01 to 20% by weight, preferably 0.1 to 1% by weight.
0% by weight.

As the solution A containing an amine component, for example, water can be used as long as it is a polar solvent which dissolves the amine component to be used well and does not dissolve the microporous support to be used.

In the solution B containing the acid halide component, the concentration of the acid halide is not particularly limited, but is usually 0.001 to 10% by weight, preferably 0.1% by weight.
01 to 5% by weight.

The organic solvent solution containing the acid halide component may be any solution which dissolves the acid halide component to be used well and is immiscible with the polar solvent to be used. Examples thereof include aliphatic and alicyclic compounds having 5 to 10 carbon atoms. Formula hydrocarbons are used,
Specifically, pentane, hexane, heptane, octane,
Cyclopentane and the like can be mentioned.

In this way, the polar solvent solution containing the amine component is coated on the microporous support, and after removing the excess solution, the solvent solution containing the acid halide component is coated thereon. Then, the excess solution is removed and interfacial polymerization is performed in situ to form a thin film. At the same time, a crosslinking reaction proceeds.

Further, a heat treatment can be performed if necessary. The heating temperature is 40 to 180 ° C, preferably 50 to 180 ° C.
150 ° C., and the heating time is 10 seconds to 60 minutes, preferably 1 to 30 minutes.

Next, a solution containing an amine compound having at least 4 amino groups and 10 or more carbon atoms is a solvent which dissolves the amine compound and does not immediately react with the acid halide component. I just need.

The concentration of the amine compound is not particularly limited, but is usually 0.01 to 20% by weight, preferably 0.1 to 20% by weight.
05 to 10% by weight.

[0035]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

As the microporous support, a polysulfone ultrafiltration membrane was used. The performance of the obtained composite reverse osmosis membrane was determined by allowing an aqueous solution of pH 6.5 containing 1500 mg / liter of sodium chloride to pass through the composite reverse osmosis membrane at an operating pressure of 15 kgf / cm ² and a temperature of 25 ° C. for 1 hour. , Sodium chloride rejection, and permeation flux. The sodium chloride rejection was determined by ordinary conductivity measurement.

(Example 1) m-phenylenediamine was added to 2
An aqueous solution A containing 0.5% by weight of sodium lauryl sulfate, 0.5% by weight of sodium lauryl sulfate, 2% by weight of triethylamine, 4% by weight of camphorsulfonic acid, and 20% by weight of isopropyl alcohol is a polysulfone-based ultrafine support. After coating on the filtration membrane, excess aqueous solution was removed to form a layer of the aqueous solution on the support. Next, a hexane solution containing 0.15% by weight of trimesic acid chlorite was prepared as a solution B on the support, and was brought into contact with the solution A.
Thereby, an interfacial polycondensation reaction and a crosslinking reaction occurred, and a polyamide thin film was formed.

Thereafter, the amine compound represented by the following formula (Formula 13) was brought into contact with a t-butyl alcohol solution containing 2% by weight, and then kept in a dryer at 120 ° C. for 3 minutes to obtain a microporous support. A polymer thin film was formed on the body to obtain a composite reverse osmosis membrane.

[0039]

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When the performance of the obtained composite reverse osmosis membrane was evaluated, the rejection of salt was 99.5% and the permeation flux was 2.0 m ³ /.
m ² · d. When the zeta potential of the membrane surface was measured, the value at pH 6 was 10 mv.

Comparative Example 1 A composite reverse osmosis membrane was prepared in the same manner as in Example 1 except that the solution was not brought into contact with the solution containing the amine compound represented by the above formula (Formula 13). . The performance of the obtained composite reverse osmosis membrane is
The rejection of salt is 99.7%, and the permeation flux is 1.7 m ³ / m ^2.
d. When the zeta potential of the membrane surface of the membrane was measured, the value at pH 6 was -40 mv.

Example 2 The membrane of Comparative Example 1 was used in the first stage, and the membrane of Example 1 was used as the second stage for supplying permeated water.
, A film having a conductivity of 100 μs / cm and a pH of 6.
When the specific resistance of the second-stage permeated water was measured using the well water of No. 5 as a stock solution, the specific resistance was 7.0 MΩ · cm.

(Comparative Example 2) The same procedure as in Example 2 was carried out except that the film of Comparative Example 1 was used in the first and second stages. When the specific resistance of the second stage permeated water was measured, the specific resistance was 3.0 MΩ · c.
m.

[0044]

As described above, the present invention relates to a composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the thin film, wherein the thin film comprises a polyfunctional amine component and a polyfunctional acid halide component. Is a polyamide thin film obtained by an interfacial polycondensation reaction and a cross-linking reaction, and the thin film has at least 4 amino groups and 10 or more carbon atoms of an amine compound residue chemically bonded. In addition, it is possible to provide a composite reverse osmosis membrane which is excellent in desalting inorganic salts and eliminating cationic organic substances in a low concentration region and has a high permeation flux.

The production method of the present invention can efficiently and rationally produce the composite reverse osmosis membrane.

The method of use of the present invention further comprises the step of using the composite reverse osmosis membrane described in any of the above in any of the steps of multistage reverse osmosis membrane treatment, thereby desalting inorganic salts in a low-concentration region and preparing cations. It is possible to perform a treatment that excels in removing organic organic matter and also has a high permeation flux.

Claims (8)

[Claims] 1. A composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the thin film, wherein the thin film is formed by an interfacial polycondensation reaction and a cross-linking reaction between a polyfunctional amine component and a polyfunctional acid halide component. A composite reverse osmosis membrane comprising a polyamide thin film obtained by the above method, wherein the thin film has an amine compound residue having at least 4 amino groups and 10 or more carbon atoms chemically bonded. 2. The composite reverse osmosis membrane according to claim 1, wherein the membrane surface zeta potential at pH 6 is positive. 3. The film according to claim 1, wherein the surface of the thin film is cationic.
3. The composite reverse osmosis membrane according to item 1. 4. The compound reverse compound according to claim 1, wherein the amine compound residue having at least 4 amino groups and 10 or more carbon atoms is represented by any of the following chemical formulas (Chemical Formulas 1 to 4). Permeable membrane. Embedded image Embedded image Embedded image Embedded image 5. The composite reverse osmosis membrane according to claim 1, wherein the thin film is composed of a residue of an aromatic polyfunctional amine component and a residue of an aromatic polyfunctional acid halide component. 6. A method for producing a composite reverse osmosis membrane comprising a thin film and a microporous support supporting the thin film, wherein (a) at least two amino groups selected from primary and secondary amino groups are provided. A solution A containing an essentially monomeric amine compound and a solution B containing an essentially monomeric acid halide compound having at least two or more acid halide groups, (c) After the contact and the interfacial polycondensation reaction and the cross-linking reaction to form a polyamide thin film, (d) the thin film has at least four amino groups selected from primary and secondary and has 10 carbon atoms. A method for producing a composite reverse osmosis membrane, comprising contacting and chemically bonding a solution containing an amine compound having at least two amine compounds. 7. The composite reverse osmosis membrane according to claim 6, wherein the amine compound having at least 4 amino groups and 10 or more carbon atoms is represented by any of the following chemical formulas (Formulas 5 to 8). Manufacturing method. Embedded image Embedded image Embedded image Embedded image 8. A method for using a composite reverse osmosis membrane, wherein the composite reverse osmosis membrane according to claim 1 is used in any one of steps of a multistage reverse osmosis membrane treatment.