JP2000237560A - High permeability composite reverse osmosis membrane and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the deposition of insoluble components as well as to reliably remove organic substances even in operation under the low pressure of tap water by forming a thin film supported on a microporous substrate from a specified amine compound and a monomeric compound having groups reactive with amino groups. SOLUTION: In a composite reverse osmosis membrane comprising a thin film and a microporous substrate which supports the thin film, the thin film is formed from an amino compound including one kind selected from polyvinyl alcohol type amine compounds having two primary and secondary side chain amino groups and a component including one kind selected from essentially monomeric compounds having two or more groups reactive with amino groups. The amine compound is preferably represented by the formula, wherein a>0, b>=0, c>2, 1<=x<=5, 0<=y<=4, R1 is at least one group selected from ether or the like and R2 is at least one group selected from alkyl or the like.

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, and a method for producing the same. In particular, the present invention relates to a composite reverse osmosis membrane suitably used for removing harmful substances such as trihalomethane precursors and pesticides in water purification, and for removing and recovering effective substances in the food field and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a reverse osmosis membrane having a structure different from that of an asymmetric reverse osmosis membrane, a composite reverse osmosis membrane formed by forming an active thin film having substantially selective separation on a porous support is known. Are known.

[0003] For example, there are many proposals in which a thin film made of polyamide obtained by interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide is formed on a support (for example, Japanese Patent Application Laid-Open No. H10-163,878). JP-A-55-147106, JP-A-62-121603, JP-A-63-218208, JP-A-2-
No. 187135).

It is also known to incorporate a hydrophilic group into a membrane in order to increase water permeability (see, for example,
7-119928, JP-A-59-179103, JP-A-62-53
No. 703, etc.). Furthermore, it has been proposed to increase the water permeability by incorporating a hydrophilic group into the membrane and then performing a post-treatment with an aqueous alkali solution (for example, JP-A-63-7807).

Further, a polyvinyl alcohol-based polyamide reverse osmosis membrane having strong hydrophilicity is also disclosed in JP-B-59-27202,
JP-B-61-17521, JP-B 2-32009, JP-A-6
It is proposed in Japanese Patent Publication No. 1-17521.

However, all membranes have a salt rejection of more than 90% and a permeated water amount of 0.2 m ² / m ² · d · kg / c.
m ² ) or less, and at a pressure level of tap water of 2 kg / cm ² , the amount of permeated water is as low as 0.4 m ³ / m ² · d. For practical use, increase the membrane area or obtain an appropriate amount of permeated water. Therefore, a booster pump is required. In addition, since the salt rejection rate is high, the salt concentration in the concentrated water increases when the operation is performed at a high recovery rate, and CaCO 3
Insoluble substances such as ₃ and Si precipitate on the membrane surface, causing troubles such as a significant decrease in the amount of permeated water.

[0007]

The above-mentioned composite reverse osmosis membrane comprises:
In any case, the membrane performance is generally exhibited only when the device is operated under a low to medium pressure of an operation pressure of 10 kg / cm ² or more, and there is a problem that equipment and running costs are high. For this reason, the operating pressure has recently been increased to 5 kg in terms of economy.
A composite reverse osmosis membrane that can remove organic substances and has an economical amount of permeated water even when operated under a lower operating pressure of tap water such as 3 kg / cm ² or less, for example, 3 kg / cm ² is required. Have been. Increasing the recovery rate (= permeated water amount / supplied water amount) can reduce the amount of supplied water and concentrated water when trying to obtain a certain fixed amount of permeated water. There are many advantages, such as lower wastewater treatment costs. However, the high recovery rate when considering concentrated water
Since the concentration ratio is increased, insoluble components are likely to precipitate and contaminate the surface of the reverse osmosis membrane, so that the reverse osmosis membrane is easily clogged. So for example 8
There is a need for a composite reverse osmosis membrane in which insoluble components are unlikely to precipitate even at a high recovery rate of 0% or more.

The present invention solves the above-mentioned problems, and can remove organic substances even when operated under a low tap water level operation pressure of, for example, 3 kg / cm ² , Another object of the present invention is to provide a composite reverse osmosis membrane which has an economical permeated water amount and in which insoluble components are hardly precipitated even at a high recovery rate, and a method for producing the same.

[0009]

In order to achieve the above object, a composite reverse osmosis membrane of the present invention comprises a composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the thin film, wherein the thin film comprises a) an amine compound containing at least one selected from polyvinyl alcohol-based amine compounds having at least two primary and secondary side chain amino groups, and (b) at least two groups capable of reacting with the amino group. And a component containing at least one selected from the group of essentially monomeric compounds having at least one compound.

In the reverse osmosis membrane, the amine compound (a) is preferably represented by the following formula (Formula 3).

[0011]

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The reverse osmosis membrane further comprises an amine component containing at least one amine compound selected from aromatic, aliphatic and alicyclic polyfunctional amines in combination with the amine compound (a). May be.

In the reverse osmosis membrane, the compound (b) is preferably an acid halide.

In the reverse osmosis membrane, the compound (b) is preferably at least one polyfunctional acid halide compound selected from aromatic, aliphatic and alicyclic compounds.

In the reverse osmosis membrane, the porous support has a pore size of 10 to 500 Å (1 Å) on the surface.
It is preferably an ultrafiltration membrane having pores of ５０50 nm).

In the reverse osmosis membrane, when the composite reverse osmosis membrane is evaluated at an operating pressure of 5 kg / cm ² , a temperature of 25 ° C. and a pH 6.5 aqueous solution containing 500 mg / liter of sodium chloride, the permeation flux is evaluated. Is 1.0 m ³ / m ² · d
It is preferable that it is above.

In the reverse osmosis membrane, when the composite reverse osmosis membrane was evaluated with an aqueous solution containing 500 mg / liter of sodium chloride at a temperature of 25 ° C. and an operating pressure of 5 kg / cm ² at a pH of 6.5, the salt rejection rate was reduced. Is preferably 80% or less.

Next, the method for producing a highly permeable composite reverse osmosis membrane according to the present invention comprises the steps of: (a) forming a polyvinyl alcohol having at least two primary and secondary side chain amino groups on the surface of a microporous support; (B) a solution containing at least one amine compound selected from a group of amine compounds and a polar solvent, and (b) a group of essentially monomeric compounds having at least two groups capable of reacting with the amino group. And contacting at least one of them with a solution containing an organic solvent to cause an interfacial polymerization reaction to form a reverse osmosis membrane.

In the above method, the amine compound component (a) is preferably represented by the following formula (Formula 4).

[0020]

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[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, at least two
At least one amine compound selected from polyvinyl alcohol-based amine compounds having one or more primary and secondary side chain amino groups is used as a raw material for the thin film. When the group that reacts with the amine compound is an acid halide group, a polyamide film is obtained by interfacial polycondensation.

Aromatic, aliphatic or alicyclic polyfunctional amines and the like can be used in combination with these amine compounds.

Examples of such aromatic polyfunctional amine compounds include m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5-diamino Examples include benzoic acid, 2,6-diaminotoluene, 2,4-diaminoanisole, xylylenediamine and the like.

As the aliphatic polyfunctional amine compound,
For example, ethylenediamine, propylenediamine, tris (2-aminoethyl) amine and the like can be mentioned.

The alicyclic polyfunctional amine compounds include:
Examples include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine and the like.

Further, a group capable of reacting with an amino group of a component containing at least one selected from the group of essentially monomeric compounds having at least two groups capable of reacting with an amino group used in the present invention. As an acid halide group,
Examples include isocyanate groups and carboxylic acid groups. Among these, an acid halide group is preferred from the viewpoint of reactivity. Particularly, an acid chloride group is preferable.

The polyfunctional acid halide used in the present invention is not particularly limited, and examples thereof include aromatic, aliphatic and alicyclic 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 chloride, benzenetrisulfonic acid chloride, benzenedisulfonic acid chloride, and the like. Chlorosulfonylbenzenedicarboxylic acid chloride and the like can be mentioned.

Examples of the aliphatic polyfunctional acid halides include, for example, 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 and tetrahydrochloride. Furantetracarboxylic acid chloride, cyclopentanedicarboxylic acid chloride, cyclobutanedicarboxylic acid chloride, cyclohexanedicarboxylic acid chloride, tetrahydrofurandicarboxylic acid chloride and the like can be mentioned.

In the present invention, a thin film containing a crosslinked polymer as a main component is formed on a microporous support by subjecting the amine component and a component capable of reacting with the amine component to an interfacial polymerization reaction. A composite reverse osmosis membrane is obtained.

In general, the interfacial polymerization reaction is carried out at an interface between a solution containing an amine component and a polar solvent and a solution containing a compound having a group capable of reacting with the amine component and an organic solvent.

An operation pressure of 5 kg / c is applied to the composite reverse osmosis membrane.
m ^2, permeation flux as assessed with an aqueous solution of pH6.5 containing sodium chloride 500 mg / l it is preferably 1.5m ³ / m ² · d or more at 25 ° C.. When the permeation flux is less than 1.0 m ³ / m ² · d, for example, 3 kg / m
When operated under lower tap water operating pressures such as cm ² , sufficient permeate flux is not obtained. For this purpose, a more preferred flux is 1.5 m ³ / m ² ·
d or more.

An operating pressure of 5 kg / c is applied to the composite reverse osmosis membrane.
The salt rejection is preferably 80% or less when evaluated with an aqueous solution containing 500 mg / 1 of sodium chloride and having a pH of 6.5 at 25 ° C. and m ² . When the salt rejection exceeds 80%, insoluble components are likely to precipitate under high recovery conditions, and the surface of the reverse osmosis membrane is easily contaminated and clogged. More preferably, the salt rejection is 70% or less.

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

Also, amine salts described in JP-A-2-187135, for example, salts of tetraalkylammonium halides and trialkylamines with organic acids can be easily formed into a film, and the amine solution can be applied to a support film of an amine solution. It is preferably used in terms of improving the absorbability of the compound and accelerating the condensation reaction.

The solubility parameter described in JP-A-8-224452 is from 8 to 14 (cal / cm ³ ) ^1/2.
The presence of the above substance in the cross-linking reaction field is also effective in increasing the amount of permeated water.

Further, a surfactant such as sodium dodecylbenzenesulfonate, sodium dodecyl sulfate and sodium lauryl sulfate can be added. These surfactants are effective in improving the wettability of a solution containing a polar solvent having 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.

The concentration of the amine compound in the solution containing the polar solvent having the amine component is not particularly limited, but is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight. .

Examples of the polar solvent having an amine component include:
Any polar solvent can be used as long as it can dissolve the amine component to be used well and does not dissolve the microporous support to be used, such as water.

In a solution containing an organic solvent containing a compound having a group capable of reacting with the amino component, the concentration of the compound is not particularly limited, but is usually 0.03.
It is from 0.01 to 10% by weight, preferably from 0.01 to 5% by weight.

The organic solvent containing the acid halide component may be any organic solvent which dissolves the acid halide component to be used well and is immiscible with the polar solvent to be used. A hydrocarbon is used, and specific examples thereof include pentane, hexane, heptane, octane, and cyclopentane.

In this way, the solution containing the polar solvent containing the amine component is coated on the microporous support, the excess solution is removed, and then the organic solvent containing the acid halide component is contained thereon. Coat the solution, remove the excess solution,
A thin film is formed by interfacial polymerization in situ.

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.

[0045]

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

As the porous support, a polysulfone ultrafiltration membrane was used. The performance of the resulting composite reverse osmosis membrane was determined by allowing an aqueous solution of pH 6.5 containing 500 mg / liter of sodium chloride to pass through the composite reverse osmosis membrane at an operating pressure of 5 kgf / cm ² and a temperature of 25 ° C. for 1 hour. The sodium chloride rejection and the permeation flux were measured. The sodium chloride rejection was determined by ordinary conductivity measurement.

Example 1 2% by weight of a polyvinyl alcohol-based amine compound having a side chain amino group represented by the following formula (Formula 5), 0.5% by weight of sodium lauryl sulfate, and 0.1% by weight of sodium hydroxide. After an aqueous solution containing 5% by weight was applied to a polysulfone ultrafiltration membrane as a microporous support, an excess aqueous solution was removed to form a layer of the aqueous solution on the support.

[0048]

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Then, on such a support, an isooctane solution containing 1% by weight of trimesic acid chloride was contacted,
Interfacial polycondensation was carried out, and the mixture was kept in a dryer at 120 ° C. for 3 minutes to form a polymer thin film on the microporous support, thereby obtaining a composite reverse osmosis membrane.

When the performance of the obtained composite reverse osmosis membrane was evaluated, the rejection of salt was 50% and the permeation flux was 3.2 m ³ / m ^2.
-It was d. After the membrane was passed through an alkaline solution having a pH of 12 for 3 days, the performance was evaluated under the same conditions. The salt rejection was 48%, the permeation flux was 3.3 m ³ / m ² · d, and the alkali resistance was also high. There was enough.

(Examples 2 to 4) A composite reverse osmosis membrane was prepared in the same manner as in Example 1 except that the concentration of trimesic acid chloride in Example 1 was changed. Table 1 shows the performance of the obtained composite reverse osmosis membrane.

[0052]

[Table 1]

As is evident from Table 1, the products of the present invention show a high permeation flux even at a pressure as low as 5 kg / cm ² , and at an operating pressure of a tap water level as low as 3 kg / cm ^2. It was confirmed that a sufficiently high permeation flux could be obtained even during operation.

Comparative Example 1 A composite reverse osmosis membrane was obtained in the same manner as in Example 1, except that m-phenylenediamine was used instead of the polyvinyl alcohol-based amine compound.

When the performance of the obtained composite reverse osmosis membrane was evaluated, the rejection of salt was 99% and the permeation flux was 0.05 m ³ /.
The permeation flux was remarkably low at m ² · d.

[0056]

As described above, the composite reverse osmosis membrane of the present invention is a composite reverse osmosis membrane comprising a thin film and a microporous support for supporting the thin film, wherein the thin film comprises (a) at least 2
An amine component containing at least one selected from polyvinyl alcohol-based amine compounds having one or more primary and secondary side chain amino groups; and (b) an essence having at least two or more groups capable of reacting with the amino group. When operating under a low tap water level operating pressure, for example, an operating pressure of 3 kg / cm ² , by being formed from components containing at least one selected from the group of monomeric compounds In addition, it is possible to provide a composite reverse osmosis membrane capable of removing organic substances, having an economical amount of permeated water, and hardly depositing insoluble components even at a high recovery rate.

According to the production method of the present invention, the composite reverse osmosis membrane of the present invention can be efficiently and rationally produced.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08F 8/00 C08F 8/00 C08G 69/00 C08G 69/00 F term (reference) 4D006 GA03 GA06 KE03R KE06R KE15R KE16R MA06 MA09 MA22 MA25 MB02 MB20 MC32. AD02R AE09P AG04Q BA29P BA35H BA57H BC02H BC03H BC04H BC43H BC43P BC49H BC53H CA05 HA61 HC28 JA00

Claims (9)

[Claims] 1. A composite reverse osmosis membrane comprising a thin film and a microporous support supporting the thin film, wherein the thin film comprises: (a) polyvinyl alcohol having at least two primary and secondary side chain amino groups An amine component containing at least one selected from the group consisting of amine compounds, and (b) at least one selected from the group of essentially monomeric compounds having at least two groups capable of reacting with the amino group. A highly permeable composite reverse osmosis membrane characterized by comprising: 2. An amine compound represented by the following formula (1):
The highly permeable composite reverse osmosis membrane according to claim 1, which is represented by: Embedded image 3. An aromatic compound which is used in combination with the amine compound (a),
The highly permeable composite reverse osmosis membrane according to claim 1, further comprising an amine component containing at least one amine compound selected from aliphatic and alicyclic polyfunctional amines. 4. The highly permeable composite reverse osmosis membrane according to claim 1, wherein the compound (b) is an acid halide. 5. The highly permeable composite reverse osmosis membrane according to claim 4, wherein the compound (b) is at least one polyfunctional acid halide compound selected from aromatic, aliphatic and alicyclic compounds. 6. A composite reverse osmosis membrane having an operating pressure of 5 kg / cm ² , a temperature of 25 ° C., and a permeation flux of 1.0 m ³ / cm ² when evaluated with an aqueous solution of pH 6.5 containing 500 mg / l of sodium chloride. The highly permeable composite reverse osmosis membrane according to claim 1, which has an m ² · d or more. 7. An operating pressure of 5 kg / c for the composite reverse osmosis membrane.
The highly permeable composite reverse osmosis membrane according to claim 1, which has a salt rejection of 80% or less when evaluated with an aqueous solution of pH 6.5 containing 500 mg / liter of sodium chloride at m ² and a temperature of 25 ° C. 8. A polar solvent comprising: (a) at least one amine compound selected from polyvinyl alcohol-based amine compounds having at least two primary and secondary side chain amino groups on the surface of a microporous support; And (b) at least one compound selected from the group of essentially monomeric compounds having at least two groups capable of reacting with the amino group.
A method for producing a highly permeable composite reverse osmosis membrane, comprising contacting a seed with a solution containing an organic solvent to cause an interfacial polymerization reaction to form a reverse osmosis membrane. 9. The method for producing a highly permeable composite reverse osmosis membrane according to claim 8, wherein the amine compound component (a) is represented by the following formula (Formula 2). Embedded image