JP3284115B2 - Method for producing polyamide reverse osmosis composite 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 reverse osmosis composite membrane used for desalinating brackish water or seawater for industrial water, agricultural water, and domestic water.

[0002]

2. Description of the Related Art Solutes can be separated from a solvent by a selective membrane such as a microfiltration membrane, an ultrafiltration membrane, or a reverse osmosis membrane. With desalination treatment using a reverse osmosis membrane, by applying pressure equal to or higher than the osmotic pressure to brackish water or seawater and filtering through a reverse osmosis membrane, the dissolved ions or molecules are separated, and only purified water that has passed through the membrane is obtained. It is a mechanism. Here, the osmotic pressure acts in the reverse direction of the filtration step, and the osmotic pressure increases as the solute concentration in the feed water increases.

In order to carry out desalination treatment of a large amount of brackish water or seawater on a commercial scale in the reverse osmosis membrane method, the reverse osmosis membrane requires a high permeation amount (that is, a large amount of water is applied at a low pressure). ), And high salt rejection. Except for the special case where only the permeated amount is regarded as important and a high desalination rate is not required, the use of purified water at a commercial level generally requires that the desalination rate be 97% or more. The amount of permeation is 8 for seawater.
10 gfd (gallons / ft ² day) for a pressure of 00 psi
In the case of brackish water, 15 gfd
The above is required.

[0004] In the reverse osmosis membrane method, a composite membrane in which a polyamide membrane is formed on a porous support layer is generally used as the reverse osmosis membrane. As a typical polyamide film, there is a film obtained by interfacial polymerization of a polyfunctional amine and a polyfunctional acyl halide.

[0005] In this regard, Cadotte teaches in US Pat.
No. 277,344, fragrance obtained by interfacial polymerization of an aromatic polyfunctional amine having two or more primary amino groups and an aromatic polyfunctional acid halide having three or more acyl halide functional groups. A technique relating to an aromatic polyamide thin film is disclosed. Specifically, on a microporous polysulfone support,
After coating an aqueous solution of m-phenylenediamine, excess metaphenylenediamine is removed, and “FREON” TF (trichlorotrifluoroet
It describes that the above polyamide thin film was obtained by reacting the above polyamide thin film with a trimesic acid chloride solution in a solvent.

[0006] Tomashke is disclosed in US Pat.
No. 2,984 (registered October 1989), (a)
An aqueous solution containing (1) an aromatic polyamine which is essentially a monomer having two or more amino groups, and (2) an amine salt compound of a monomer is applied to a microporous support material to form a liquid. Forming a layer, (b) a polyfunctional acyl halide having essentially 2.2 or more acyl halide groups per molecule, or a mixture thereof, essentially a monomeric aromatic polyfunctional acid halide compound The method discloses a method for producing a reverse osmosis membrane, which comprises the steps of: bringing a liquid solution into contact with an organic solution containing the compound to carry out a reaction; and (c) drying the product.

[0007] Chau is also disclosed in US Patent No. 4,983,2.
No. 91 (registered in January 1991) discloses a membrane formed by forming a polymerization reaction product on and / or in a porous support layer. Specifically, an aprotic polar solvent, a polyamine aqueous solution containing a polyhydroxide serving as an acid acceptor is applied to the support layer, and after removing excess solution, an organic solution in which the polyacyl halide is dissolved is placed on the support layer. And a polymerization reaction is carried out. It discloses that the obtained composite membrane was treated with hydroxypolycarboxylic acid, polyaminoalkylenepolycarboxylic acid, sulfonic acid, amine salt, amino acid, polymer acid, inorganic acid, etc., and then dried to obtain a reverse osmosis membrane. are doing.

Further, Hirose has been disclosed in US Pat. No. 5,614,614.
No. 099 (registered March 1991), a reverse osmosis composite membrane characterized in that the average surface roughness (roughness) of the polyamide surface layer is 55 nm or more. It discloses that it is a reactant with a polyfunctional acid halide having an acid function. Specifically, after applying a metaphenylenediamine solution to the support layer, trimesic acid chloride (trimesic chlorid
e) A method for forming a polyamide surface layer on a support layer by contacting an organic solution and drying a film obtained by an interfacial polymerization reaction with high-temperature hot air is proposed.

Although the above-mentioned membrane of Cadotte et al. Shows a good permeation rate and a good salt removal rate, in practical use, the permeation rate and the permeation rate of a polyamide reverse osmosis composite membrane are intended to obtain a more economical membrane. There is a need for further improvements in salt removal rates. There is also room for improvement in the chemical resistance of the film.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a polyamide reverse osmosis which can achieve a higher permeation amount and a higher salt removal rate than the above-mentioned conventional methods. It is to provide a composite membrane.

[0011]

The method for producing a reverse osmosis membrane according to the present invention, which has achieved the above objects, comprises a polyfunctional amine and a polar compound selected from the following first to third groups. Aqueous solution and a polyfunctional acyl halide, a polyfunctional sulfonyl halide, an organic solution containing an amine-reactive compound having a reactivity with an amino group selected from the group consisting of polyfunctional isocyanates. The point is that the polyamide film is formed on the porous support layer.

Group 1 compounds: 1,2-alkanediol, 1,3-alkanediol, diethylene glycol hexyl ether, diethylene glycol tert-butyl methyl ether, diethylene glycol dimethyl ether, dipropylene glycol monoalkyl ether, triethylene glycol dimethyl ether, , X-cyclohexanedimethanol (x is an integer of 2 to 4).

Group 2 compound: at least one compound selected from alkoxyalkanols.

Group 3 compounds: alkoxyethanol and propylene glycol, alkoxyethanol and sulfoxide derivatives, alkoxyethanol and urea, diethylene glycol hexyl ether and propylene glycol,
At least one selected from the group consisting of diethylene glycol hexyl ether and a sulfoxide derivative, diethylene glycol hexyl ether and glycerol, 1,3-alkanediol and a sulfoxide derivative, and propylene glycol and propylene glycol monoalkyl ether.

[0015] In the production method of the present invention, it is preferable that after the aqueous solution is coated on the porous support layer, the organic solution is brought into contact with the solution to perform interfacial polymerization.

The porous support layer may be made of polysulfone, polyethersulfone, polyimide, polyamide,
Those made of a material selected from the group consisting of polypropylene and polyvinylidene fluoride are preferred.

The polar compound is contained in the aqueous solution in an amount of 0.01
It is preferably set to 8%.

Further, when the first group compound is used as a polar compound, 0.1 to 4% of the second group compound is used in the aqueous solution.
When a group compound is used, 0.05 to 4
%, When the third group compound is used, it is preferably 3 to 4% in the aqueous solution.

When diethylene glycol hexyl ether is used among the first group compounds, it is preferably contained in the aqueous solution at 0.1 to 3%.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, requirements constituting the present invention will be described specifically.

The reverse osmosis composite membrane in the present invention is obtained by forming a polyamide membrane on a porous support layer.
The polyamide film is obtained by an interfacial polymerization reaction by contacting an aqueous solution containing a polar compound and a polyfunctional amine with an organic solution containing an amine-reactive compound.

As the porous support layer, a microporous support layer is generally used and is not particularly limited.
The pore size of the support layer is desirably large enough to allow permeated water to sufficiently pass through. However, if the thickness exceeds 300 nm, the ultrathin film sinks into the air gap, making it difficult to obtain a flat film state.

As the material of the microporous support layer, it is desirable to use a halogenated polymer such as polysulfone, polyether sulfone, polyimide, polyacrylonitrile, polypropylene, or polyvinylidene fluoride.

The thickness of the microporous support layer is not particularly limited, but is preferably 25 to 125 μm.
More preferably, it is 40 to 75 μm.

The polyfunctional amine used in the present invention is preferably a monomeric amine having two or more amino groups.
Those having from 3 to 3 amino groups are more preferred. Also,
The amino group is preferably a primary or secondary amino group, more preferably a primary amino group.

Examples of the polyfunctional amine include metaphenylenediamine, paraphenylenediamine and substituted derivatives thereof. Examples of the substituent include an alkyl group such as a methyl group and an ethyl group, an alkoxyl group, a hydroxyalkyl group,
It contains a hydroxyl group or a halogen atom. In addition, 1,3-propanediamine which is a chain alkanediamine, N
1,3-propanediamine derivatives having an alkyl group or an N-aryl group, cyclohexanediamine as an alicyclic primary diamine, piperazine as an alicyclic secondary diamine, piperazine alkyl derivative, and aromatic secondary diamine. N, N'-dimethyl-1,3-phenylenediamine, N, N'-diphenylethylenediamine, or benzidine, xylenediamine and derivatives thereof, and the like.

The above-mentioned polyfunctional amine is added to the above aqueous solution at a concentration of 0.1%.
It is desirable to adjust so as to be 1 to 20%, more preferably 0.5 to 8%.

It is preferable that the above aqueous solution is used after being adjusted to pH 7 to 13. For pH adjustment at this time, an acid acceptor may be added so as to be 0.001 to 5% in the above aqueous solution. Examples of the acid acceptor include a hydroxide, a carboxylate, a carbonate, a borate, a phosphate, and a trialkylamine of an alkali metal.

The polar compound is selected from the following first to third group compounds and used. The concentration is 0.01 to 8% (more preferably 0.1 to 8%) in the aqueous solution.
4%).

The first group compounds include 1,2-alkanediol, 1,3-alkanediol, diethylene glycol hexyl ether, diethylene glycol-t-
Butyl methyl ether, diethylene glycol dimethyl ether, dipropylene glycol monoalkyl ether, triethylene glycol dimethyl ether, 1, x
-Cyclohexanedimethanol (x is an integer of 2 to 4).

Specific examples of the 1,2-alkanediol include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, and 1,3-alkanediol. Is 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,3-pentanediol, 2,2-
Examples of diethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and dipropylene glycol monoalkyl ether include dipropylene glycol methyl ether, dipropylene glycol butyl ether, and dipropylene glycol-t-butyl ether. No. Other examples include propylene glycol propyl ether and propylene glycol butyl ether.

When the above-mentioned first group compound is used, it is preferably contained in an amount of 0.1 to 4% in the above aqueous solution. Further, when diethylene glycol hexyl ether is used, the content is preferably 0.01 to 3%, more preferably 0.1 to 3%, in the above aqueous solution. Also, 2-
In the case where ethyl-1,3-hexanediol is used, the content is preferably 0.1 to 1% in the above aqueous solution.

The alkoxyalkanols as the second group compounds include 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol and the like.

When the second group compound is used, it is preferably 0.05 to 4%, more preferably 0.05 to 3%, further preferably 0.5 to 2% in the aqueous solution.
%.

When a compound obtained by combining two or more polar compounds is used as the third group compound, examples thereof include:
Alkoxyethanol and propylene glycol, alkoxyethanol and sulfoxide derivatives, alkoxyethanol and urea, diethylene glycol hexyl ether and propylene glycol, diethylene glycol hexyl ether and sulfoxide derivatives, diethylene glycol hexyl ether and glycerol, 1,3-alkanediol and sulfoxide derivatives, propylene glycol Propylene glycol monoalkyl ether. Here, the sulfoxide derivative includes dimethyl sulfoxide, butyl sulfoxide, methylphenyl sulfoxide, tetramethylene sulfoxide and the like. In addition, a combination of alkoxyethanol and a urea derivative (here, the urea derivative is a compound in which one or more hydrogen is substituted with an alkyl group), a combination of alkoxyethanol and glycerol, or the like may be used.

When the third group compound is used, it is desirably 3 to 4% in the above aqueous solution.

According to the method of the present invention, it was possible to obtain a thin film having excellent properties such as a high transmittance because of the effect of the polar compound of the present invention to increase the absorption of the film on the surface of the porous support layer, It is also presumed that this is due to the effect of preventing drying of the thin film caused by evaporation of the organic solvent after the interfacial polymerization reaction.

As a method for producing a reverse osmosis composite membrane, an aqueous solution containing a polyfunctional amine and a polar compound is coated on a porous support layer to form a liquid phase membrane, and then an organic solution containing the amine-reactive compound is prepared. It is desirable to carry out interfacial polymerization by bringing the solution into contact with the liquid phase film.

As the amine-reactive compound, at least one selected from the group consisting of polyfunctional acyl halides, polyfunctional sulfonyl halides, and polyfunctional isocyanates is used. The amine-reactive compound is required to be a monomer, an aromatic compound, and a polyfunctional acyl halide, and any compound that satisfies these requirements may be used. Among them, trimesic acid chloride having two or three carboxylic acid halides, isophthalic acid chloride, terephthalic acid chloride or a combination thereof is preferable.

The content of the amine-reactive compound in the organic solvent is preferably 0.005 to 5%, more preferably 0.01 to 0.5%.

It is essential that the organic solvent is insoluble in water, and hexane, cyclohexane, heptane, alkanes having 8 to 12 carbon atoms, or halogen-substituted hydrocarbons such as freons are preferable. Particularly, a mixed organic solution comprising an alkane having 8 to 12 carbon atoms is most preferable in terms of performance.

[0042]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention is not limited thereto. Modifications can be made and implemented, all of which are included in the technical scope of the present invention.

<Production Method> After the aqueous solution described above is coated on the porous support layer by hand coating or a continuous process, the excess solution on the support layer is rolled, sponged, air-nuffed, or the like. In a suitable way. Thereafter, the above-mentioned organic solution is brought into contact with the coating layer by dipping or spraying for 5 seconds to 10 seconds.
The reaction is carried out for a period of 20 minutes, more preferably 20 seconds to 4 minutes. The reaction product undergoes a post-treatment step such as drying at 40 ° C. for about 1 minute and washing with a basic aqueous solution for 1 minute to 30 minutes.

Example 1 A polysulfone support layer formed on a 140 μm-thick nonwoven fabric contained 2.0% metaphenylenediamine (MPD), 2.0% 2-butoxyethanol, and 2.0% propylene glycol. Immerse in an aqueous solution. After removal of excess solution on the support layer, the
1% trimesic acid chloride is isopa (manufactured by EXXON)
Immerse in a solution dissolved in a solvent for 1 minute to remove excess solution. After drying the obtained composite membrane at room temperature for 1 minute, about 40 minutes
Rinse with a 0.1% aqueous solution of Na ₂ CO _{3 at} ６０60 ° C. for 30 minutes or more. The performance of the obtained reverse osmosis separation membrane is 2,000 pp
As a result of measurement under a pressurized condition of 225 psi using an aqueous NaCl solution of m, the salt removal rate was 98.2% and the permeation amount was 27.5 gfd.
Met.

Example 2 As a polar compound, 1.0%
The procedure was performed in the same manner as in Example 1 except that 2-butoxyethanol and 1.0% urea were used. As a result of measuring physical properties of the obtained film, a salt removal rate was 98.8% and a permeation amount was 27.0 gfd.

Example 3 2.0% as a polar compound
The procedure was performed in the same manner as in Example 1, except that 2-butoxyethanol and 2.0% dimethyl sulfoxide were used. As a result of measuring the physical properties of the obtained film, the salt removal rate was 9
6.4% and the permeation amount was 32.2 gfd.

<Examples 4 to 16 and Comparative Examples A to X> Except that the polar compounds shown in Table 1 below were used, the procedure was performed in the same manner as in Example 1, and the physical properties of the obtained films were measured. Table 1 also shows the measurement results.

[0048]

[Table 1]

<Examples 17 to 29 and Comparative Examples Y to EE>
Example 1 except that the polar compounds shown in Table 2 below were used.
And the physical properties of the obtained film were measured.
The measurement results are also shown in Table 2.

[0050]

[Table 2]

[0051]

The present invention is constituted as described above. In the production of a reverse osmosis membrane, by using a polyfunctional amine aqueous solution to which a polar compound according to the present invention is added, it is possible to reduce the amount of the conventional polyamide membrane production method. As a result, it was possible to obtain a polyamide reverse osmosis composite membrane having both excellent characteristics of salt removal and permeation.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor No Won Kim South Korea Busan, Soyong-kook, 557 Namchun 1-dong, Samik Newbeach Apartment. (56) References JP-A-5-15750 (JP, A) JP-A-9-99228 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) B01D 71 / 56 B01D 61/02 500 B01D 71/82 510 C02F 1/44

Claims (8)

(57) [Claims] An aqueous solution containing a polyfunctional amine and a polar compound selected from the following first to third groups, a polyfunctional acyl halide, a polyfunctional sulfonyl halide, and a polyfunctional isocyanate. Producing a polyamide reverse osmosis composite membrane characterized by reacting with an organic solution containing an amine-reactive compound having reactivity with an amino group selected from the group consisting of: forming a polyamide membrane on a porous support layer. Method. Group 1 compound: 1,2-alkanediol, 1,3-alkanediol, diethylene glycol hexyl ether, diethylene glycol-t-butyl methyl ether, diethylene glycol dimethyl ether, dipropylene glycol monoalkyl ether, triethylene glycol dimethyl ether, 1, x- At least one selected from the group consisting of cyclohexanedimethanol (x is an integer of 2 to 4). Group 2 compounds: at least one selected from alkoxyalkanols. Group 3 compounds: alkoxyethanol and propylene glycol, alkoxyethanol and sulfoxide derivatives,
Alkoxyethanol and urea, diethylene glycol hexyl ether and propylene glycol, diethylene glycol hexyl ether and sulfoxide derivatives, diethylene glycol hexyl ether and glycerol,
At least one selected from a combination consisting of 1,3-alkanediol and a sulfoxide derivative, and propylene glycol and a propylene glycol monoalkyl ether. 2. The method for producing a polyamide reverse osmosis composite membrane according to claim 1, wherein after the aqueous solution is coated on the porous support layer, the organic solution is brought into contact with the solution to perform interfacial polymerization. 3. The porous support layer is made of a material selected from the group consisting of polysulfone, polyethersulfone, polyimide, polyamide, polypropylene, and polyvinylidene fluoride.
3. The method for producing a polyamide reverse osmosis composite membrane according to 1.). 4. The method according to claim 1, wherein the polar compound is contained in the aqueous solution at a concentration of 0.0
1 to 8% (meaning by weight%, the same applies hereinafter).
3. The method for producing a polyamide reverse osmosis composite membrane according to any one of 3. 5. The method for producing a polyamide reverse osmosis composite membrane according to claim 4, wherein when the first group compound is used as the polar compound, the concentration is 0.1 to 4% in the aqueous solution. 6. The method for producing a polyamide reverse osmosis composite membrane according to claim 5, wherein when diethylene glycol hexyl ether is used as the first group compound, it is contained in an amount of 0.1 to 3% in the aqueous solution. 7. The method for producing a polyamide reverse osmosis composite membrane according to claim 4, wherein when the second group compound is used as the polar compound, the content of the second group compound is 0.05 to 4% in the aqueous solution. 8. The method for producing a polyamide reverse osmosis composite membrane according to claim 4, wherein when the third group compound is used as the polar compound, the concentration is 3 to 4% in the aqueous solution.