JPH0596140A - Production of composite translucent membrane - Google Patents

Abstract

PURPOSE:To provide a production method for a composite translucent membrane having high desalting property, water permeability and resistance against oxidizing agent, especially, excellent in resistances against chlorine, chloramine, and hydrogen peroxide. CONSTITUTION:A crosslinked polyamide super-thin film layer is formed on a fiber-reinforced polysulfone fine porous supporting membrane. This crosslinked polyamide is obtd. by interfacial polycondensation of polyfunctional acid halide compd. and polyfunctional aromatic amine having two or more amino groups in one molecule. Then, the obtd. membrane is treated with the aq. soln. of peroxymono compd. or peroxy disulfuric acid compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can be used for selective separation of liquid mixtures, particularly desalination of canned water and seawater, recovery of valuables, reuse of wastewater, production of ultrapure water, and the like. The present invention relates to a method for manufacturing a semipermeable composite membrane for permeation.

[0002]

2. Description of the Related Art A composite semipermeable membrane obtained by coating a microporous support membrane with an ultrathin film layer of polyamide obtained by an interfacial polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional acid halide Is attracting attention as a reverse osmosis membrane with high properties and selective separation. As the interfacial polycondensation reaction of a polyfunctional aromatic amine and a polyfunctional acid halide, for example, JP-B-63-36803 and JP-A-62-63 are known.
Japanese Patent Laid-Open No.-121603 and Japanese Patent Laid-Open No. 2-187135 have been known so far. Further, as a material for improving the performance of a composite semipermeable membrane formed by coating an ultrathin film layer made of this polyamide on a microporous support membrane, for example, Japanese Patent Laid-Open Publication No. Sho 6-62 is known.
Japanese Patent Laid-Open No. 3-54905 has been known so far.

[0003]

However, these membranes are required to have a practical reverse osmosis membrane, and have high permeability, high selective separation, resistance to oxidizing agents, especially chlorine resistance, chloramine resistance, and anti-oxidation resistance. It did not fully satisfy the hydrogen oxide property.
An object of the present invention is to provide a method for producing a composite semipermeable membrane having improved membrane performance, and particularly having resistance to an oxidant.

[0004]

To achieve the above object, the present invention has the following constitution.

That is, according to the present invention, an ultrathin film layer of a crosslinked polyamide is prepared from a polyfunctional aromatic amine having two or more amino groups in one molecule and a polyfunctional acid halide by interfacial polycondensation on a microporous support film. The present invention relates to a method for producing a composite semipermeable membrane, which comprises treating the composite semipermeable membrane with a persulfate compound after the formation.

The composite semipermeable membrane of the present invention comprises an ultrathin film layer having substantially separation performance, which is coated on a microporous support film having substantially no separation performance. , A crosslinked polyamide obtained by interfacial polycondensation of a polyfunctional aromatic amine and a polyfunctional acid halide.

The polyfunctional aromatic amine is an aromatic amine having two or more amino groups in one molecule, and examples of the bifunctional or more amines include m-phenylenediamine and p-.
Phenylenediamine and 1,3,5-triaminobenzene can be used. The above bifunctional or higher amines can be used alone or as a mixture.

The polyfunctional acid halide is an acid halide having two or more carbonyl halide groups,
A polyamide is provided by an interfacial polycondensation reaction with the polyfunctional aromatic amine. In the present invention, 2 in one molecule
Those containing an acid halide having one or more carbonyl halide groups are preferred. Examples of the polyfunctional acid halide include 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4
-Cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, 1,
An acid halide such as 4-benzenedicarboxylic acid can be used.

Considering the reactivity with the functional aromatic amine, the polyfunctional acid halide is preferably a polyfunctional acid chloride.

In the present invention, examples of preferable microporous support membranes include polysulfone support membranes reinforced by a cloth containing at least one selected from polyester and aromatic polyamide as a main component.

The microporous support membrane is a layer having substantially no separation performance, and is used for imparting strength to an ultrathin film layer having substantially separation performance, and has uniform fine pores. Alternatively, it is preferable to use a supporting film having a structure in which fine holes gradually increase from one surface to the other surface, and the size of the fine holes is 100 nm or less on the surface of the one surface. The above-mentioned microporous support membrane is "Millipore Filter VSWP" (trade name) manufactured by Millipore,
Although it is possible to select from various commercially available materials such as “Ultra Filter UK10” (trade name) manufactured by Toyo Roshi Kaisha, Ltd., it is usually “Office of Saline Water Research and Development Progress.” It can be manufactured according to the method described in the report “No.359 (1968). As the material, polysulfone, cellulose acetate, homopolymer such as cellulose nitrate or polyvinyl chloride or a blended material is usually used.
It is preferable to use polysulfone which has high chemical, mechanical and thermal stability. Further, the pore size is easy to control and the dimensional stability is high, and the repeating unit [A] shown by the following formula

[0012]

[Chemical 1]

It is preferable to use a polysulfone consisting of, for example, a solution of the above polysulfone in dimethylformamide (DMF) is cast on a densely woven polyester cloth or non-woven cloth to a certain thickness, and the solution is made of sodium dodecyl sulfate. By wet coagulation in an aqueous solution containing 0.5% by weight and 2% by weight of DMF, a microporous support membrane having most of the surface having fine pores having a diameter of several tens nm or less is obtained.

Next, a method of manufacturing the present composite semipermeable membrane will be described.

The ultra-thin film layer having substantially separating performance in the composite semipermeable membrane is immiscible with the aqueous solution containing the above-mentioned polyfunctional aromatic amine and the water containing the above-mentioned polyfunctional acid halide. It is formed by interfacial polycondensation using an organic solvent solution.

The concentration of the amino compound in the polyfunctional aromatic amine aqueous solution is 0.1 to 10% by weight, preferably 0.5.
It is up to 5.0% by weight, and the aqueous solution may contain a surfactant, an organic solvent, an antioxidant or the like as long as it does not interfere with the reaction between the amino compound and the polyfunctional acid halide. .. Further, a water-soluble polymer compound such as water-soluble polyvinyl alcohol may be contained within a range that does not impair the performance.

The surface of the microporous support membrane may be coated with the aqueous solution of amine as long as the aqueous solution is uniformly and continuously coated on the surface of the microporous support membrane. And a method of immersing the microporous support membrane in the aqueous solution.

Next, the excessively applied aqueous amine solution is removed by a draining process. As a method of draining, for example, there is a method of holding the film surface in the vertical direction and allowing it to flow down naturally. After draining, the membrane surface may be dried to remove all the water of the aqueous solution, but this is not always necessary.

Then, an organic solvent solution of the above-mentioned polyfunctional acid halide is applied, and a crosslinked polyamide ultrathin film layer is formed by interfacial polycondensation.

The polyfunctional acid halide in the solution is usually 0.01 to 10% by weight, preferably 0.02 to 2% by weight.
Is dissolved in an organic solvent, and an acylation catalyst such as DMF is added to the solution to promote interfacial polycondensation, which is more preferable.

The organic solvent must be immiscible with water, dissolve the acid halide and not destroy the microporous support membrane, and be inert to amino compounds and acid halides. Any of them may be used. Preferred examples include hydrocarbon compounds and trichlorotrifluoroethane, but n-hexane and trichlorotrifluoroethane are preferable in terms of reaction rate and solvent volatility. Considering the safety problem of flammability, it is more preferable to use trichlorotrifluoroethane.

The polyfunctional acid halide may be contacted with the amino compound aqueous solution phase in the same manner as the amino compound aqueous solution is coated on the microporous support membrane.

The aromatic ring of the crosslinked aromatic polyamide thus obtained is not completely bonded by only an amide bond, and a part thereof is a carboxylic acid terminal (—COOH) or an amine terminal group (—NH ₂ ). It is included. These polar groups affect the desalination rate and water permeability of the membrane.

In the present invention, the reaction between the amino group and the persulfate compound is a method of treating the composite semipermeable membrane in an aqueous solution of the persulfate compound.

The persulfate compound in the present invention is persulfuric acid (peroxymonosulfuric acid or peroxydisulfuric acid) or a salt thereof, and persulfuric acid and sodium, potassium, magnesium, calcium, ammonium or the like is used because of its stability and easy handling. Are more preferable, and specifically, sodium peroxydisulfate, potassium peroxymonosulfate, potassium peroxydisulfate, ammonium peroxydisulfate and the like can be used. Among them, potassium peroxymonosulfate is preferable in that the desalination rate and the stability of water permeability of the obtained film, the resistance to oxidizing agents, especially the chlorine resistance, the chloramine resistance, and the hydrogen peroxide resistance are substantially improved. .. The treatment of the persulfate compound aqueous solution is also effective for semipermeable membranes other than the composite semipermeable membrane of the present application.

When potassium peroxymonosulfate is used as the persulfate compound, the concentration of its aqueous solution is 0.05 to 1
0% is preferable, and a range of 0.1 to 3% is more preferable from the viewpoint of balance of handleability and membrane performance. The reaction can be easily carried out, for example, by immersing the solution in an aqueous solution of a persulfate compound adjusted to a temperature of 15 to 30 ° C., a pH of 1 to 9, preferably a pH of 4 to 6 for 1 to 120 minutes, preferably 10 to 30 minutes. ..

[0027]

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.

In the examples, the rejection rate was calculated by the following equation.

Exclusion rate [%] = [1- (solute concentration in membrane permeate / solute concentration in membrane feed)] × 100 As the permeation performance, the water permeation rate is the water per unit area per unit time. It was determined by the amount of permeation.

The fiber-reinforced polysulfone support membrane used in the present invention was produced by the following method.

Taffeta made of polyester fiber with a length of 30 cm and a width of 20 cm (150 denier multifilament yarn for both vertical and horizontal threads, weaving density vertical 90 threads / inch, horizontal 67 threads / inch, thickness 160 μm) It was fixed on a plate, a 15 wt% dimethylformamide (DMF) solution of polysulfone (Udel-P3500 manufactured by Union Carbide) was cast on the plate at a thickness of 200 μm at room temperature (20 ° C.), and immediately in pure water. A fiber-reinforced polysulfone support membrane (hereinafter abbreviated as FR-PS support membrane) is prepared by immersing in fiber and leaving it for 5 minutes. The FR-PS supporting film (thickness 210 to 2 obtained in this way
Pure water permeability coefficient of 15 μm) is 1 kg / cm ^{2 at} pressure and ² at temperature.
0.005-0.01g / cm ² · sec measured at 5 ℃
・ It was atm.

Comparative Example 1 The FR-PS support film was immersed in a 2% aqueous solution of metaphenylenediamine for 1 minute, and the support film was slowly pulled up in the vertical direction to remove excess aqueous solution from the surface of the support film.
A 0.1% solution of trimesinic acid chloride in trichlorotrifluoroethane was applied so that the surface was completely wet, and the solution was allowed to stand for 1 minute. Next, the membrane was made vertical and the excess solution was drained and removed, and then the solution was added to a 0.2% by weight aqueous solution of sodium carbonate.
Soaked for a minute.

The composite semipermeable membrane thus obtained was subjected to pH
1,500 ppm saline prepared in 6.5 was used as raw water, and 1
As a result of performing a reverse osmosis test for 20 hours under the conditions of 5 kg / cm ² and 25 ° C., the membrane performance shown in Table 1 was obtained.

Comparative Example 2 The film obtained in Comparative Example 1 had a concentration of 600 ppm and a pH of 7.0.
It was immersed in the aqueous solution of sodium hypochlorite prepared in Example 1 and treated for 2 minutes. The membrane performance after treatment was subjected to a reverse osmosis test under the same conditions as in Comparative Example 1, and as a result, the membrane performance shown in Table 1 was obtained.

Examples 1 to 3 The membranes obtained in Comparative Example 1 were dipped in an aqueous solution of potassium peroxymonosulfate adjusted to a concentration of 0.1, 1.0, 3.0% by weight and pH 6.0, and 30 Treated for minutes at room temperature. As a result of performing a reverse osmosis test on this membrane under the same conditions as in Comparative Example 1, the membrane performance shown in Table 1 was obtained.

Examples 4 to 5 The membranes obtained in Comparative Example 1 were immersed in an aqueous potassium peroxymonosulfate solution adjusted to a concentration of 1.0% by weight, pH 2 or pH 4, and treated at room temperature for 30 minutes. As a result of performing a reverse osmosis test on this membrane under the same conditions as in Comparative Example 1, the membrane performance shown in Table 1 was obtained.

Examples 6 to 7 The membranes obtained in Comparative Example 1 were immersed in an aqueous potassium peroxymonosulfate solution having a concentration of 1.0% by weight and a pH of 6.
It was treated for a certain period of time. As a result of performing a reverse osmosis test on this membrane under the same conditions as in Comparative Example 1, the membrane performance shown in Table 1 was obtained.

Examples 1 to 7 and Comparative Examples 1 and 2 Hypochlorous compounds prepared in Examples 1 to 7 and Comparative Examples 1 and 2 and subjected to a reverse osmosis test were prepared to have a concentration of 1000 ppm and a pH of 6.5. It was immersed in an aqueous solution of sodium acid for 20 hours. As a result of performing a reverse osmosis test on the membrane performance after immersion under the same conditions as in Comparative Example 1, the membrane performance shown in Table 2 was obtained.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

According to the present invention, there is provided a method for producing a composite semipermeable membrane which has high desalination and water permeability and is excellent in oxidant resistance, particularly chlorine resistance, chloramine resistance and hydrogen peroxide resistance. be able to.

Claims (7)

[Claims] 1. An ultrathin film layer of crosslinked polyamide is formed on a microporous support film from a polyfunctional aromatic amine having two or more amino groups in one molecule and a polyfunctional acid halide by interfacial polycondensation. Then, a method for producing a composite semipermeable membrane, which comprises treating with a persulfate compound. 2. The polyfunctional aromatic amine having two or more amino groups in one molecule is m-phenylenediamine and / or 1,3,5-triaminobenzene. A method for manufacturing a composite semipermeable membrane of. 3. The method for producing a composite semipermeable membrane according to claim 1, wherein the polyfunctional acid halide is a polyfunctional acid chloride. 4. A polyfunctional acid halide is 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
The composite half according to claim 1, which contains at least one selected from acid halides of 1,3,5-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid and 1,4-benzenedicarboxylic acid. Membrane production method. 5. The persulfate compound is at least one selected from peroxymonosulfate compounds and peroxydisulfate compounds.
It is a seed, The manufacturing method of the composite semipermeable membrane of Claim 1 characterized by the above-mentioned. 6. The method for producing a composite semipermeable membrane according to claim 1, wherein the microporous support membrane is made of polysulfone. 7. The method for producing a composite semipermeable membrane according to claim 1, wherein the microporous support membrane is reinforced with a cloth containing at least one selected from polyester and aromatic polyamide as a main component. ..