JP2001079373A - Production of polyamide reverse osmosis composite membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of an excellent polyamide reverse osmosis composite membrane usable in desalination treatment of surface water, sea water, etc., and higher in an amount to be permeated. SOLUTION: A polyamide film is formed on a porous support by reacting an aqueous solution containing multi-functional amine and an amine salt compound with an organic solution containing an amine-reactive compound having reactivity with amino groups and selected from the group consisting of a multi- functional acyl halide, a multi-functional sulfonyl halide and a multi-functional isocyanate. The amine salt compound is obtained by reacting a strong acid with a bivalent or higher polyamine, which is used by adding to the aqueous solution so that the content is made to be 0.1-12%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyamide reverse osmosis composite membrane capable of selectively separating various solutes from a solution.

[0002]

2. Description of the Related Art Generally, a solute can be separated from a solvent by various membranes such as a microfiltration membrane, an ultrafiltration membrane, and a reverse osmosis membrane.

[0003] Drinking water by removing salt from surface water, seawater, etc.
In the desalination treatment for obtaining agricultural water and industrial water, a method using a reverse osmosis membrane is used as the most economical method. The desalination treatment using this reverse osmosis membrane means that the salt, dissociated ions, organic molecules, etc., which are dissolved by applying a pressure higher than the osmotic pressure to the brackish water or seawater and filtering through the reverse osmosis membrane, and purifying only water It is to get. Here, the osmotic pressure acts in the reverse direction of the reverse osmosis step, and the higher the solute concentration in the feed water, the higher the osmotic pressure.

In order to treat a large volume of seawater or brackish water on a commercial or industrial scale by the desalination method using such a reverse osmosis membrane, the reverse osmosis membrane requires a high flux and a high salt removal rate. (Salt rejection) is the most important point. That is, in order for the desalination method using a reverse osmosis membrane to be more economically advantageous than other methods such as an evaporation method and an ion exchange method, for example, in the case of seawater treatment, a permeation rate of 800 psi is applied. in ^{10gfd (gallons / ft 2 · day} ) or more, 15Gfd or more 220 psi, and salt removal rate it is necessary to ensure a level of 97% or more.

[0005] In the reverse osmosis membrane method, a composite membrane in which a very thin polyamide membrane is formed on a porous support layer is most commonly used as a reverse osmosis membrane. This polyamide film is formed by interfacial polymerization of a polyfunctional amine and a polyfunctional acid halide.

In this regard, Cadotte in US Pat.
No. 77,344, an aromatic compound produced 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 acid halide groups. A polyamide membrane is disclosed. Specifically, after immersing the polysulfone support layer in an aqueous solution of metaphenylenediamine, excess metaphenylenediamine on the surface is removed, and “FREON” TF (trichlorotrifl
After applying a trimesic acid chloride solution using uoroethane as a solvent and performing a reaction (the contact time for the interfacial reaction is 10 seconds, but the reaction itself is completed within 1 second).
It describes that the product was dried in air to obtain a polysulfone / polyamide composite membrane.

[0007] For the purpose of obtaining a film having better properties, studies have been made on production methods using various additives. For example, Tomashke U.S. Pat.
No. 2,984 discloses an aqueous solution coating layer obtained by applying a water-soluble solution containing an aromatic polyfunctional amine of a monomer having two or more amino groups and an amine salt compound on a microporous support. Discloses a method for producing a reverse osmosis composite membrane by interfacial polymerization by contacting an organic solution containing an aromatic polyfunctional acid halide compound or a mixture thereof. It is disclosed that the amine salt compound used as an additive is a monomer and is a reaction product of a strong acid and a tertiary amine or a quaternary ammonium salt. Further, as the tertiary amine used at this time, trialkylamines, N-alkyl alicyclic amines, bicyclo tertiary amines, and quaternary ammonium salts include tetraalkylammonium hydroxide, benzyltrialkylammonium hydroxide and the like. And mixtures thereof. However, only a monovalent tertiary amine is mentioned here as the tertiary amine, and a divalent or higher tertiary amine is not mentioned.

[0008] Although the above-mentioned membrane of Cadotte et al. Shows a good permeation amount and a low salt removal rate, in practical use, the permeation amount and the salt removal rate of the reverse osmosis membrane are further improved in order to reduce the operation cost. Further improvements are required. In addition, there is room for improvement regarding chemical denaturation against chemical decomposition and the like.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to achieve an excellent permeation rate and a high salt removal rate, particularly a high permeation rate, as compared with existing reverse osmosis membranes. An object of the present invention is to provide an obtained polyamide reverse osmosis composite membrane.

[0010]

The method for producing a reverse osmosis membrane according to the present invention, which has achieved the above objects, comprises an aqueous solution containing a polyfunctional amine and an amine salt compound, a polyfunctional acyl halide, and a polyfunctional acyl halide. Reacting with an organic solution containing an amine-reactive compound having a reactivity with an amino group selected from the group consisting of reactive sulfonyl halides and polyfunctional isocyanates to form a polyamide film on the porous support layer In the production of the composite film, the gist is that an amine salt compound obtained by a reaction between a strong acid and a polyamine having a valency of 2 or more is added as the amine salt compound so as to be 0.1 to 12% in the aqueous solution. Things.

In the present invention, as the strong acid, aromatic sulfonic acid, aliphatic sulfonic acid, alicyclic sulfonic acid,
It is preferable to use an acid selected from the group consisting of trifluoroacetic acid, nitric acid and hydrochloric acid.

The polyamine having a valency of 2 or more is 3 or more.
Compounds having a secondary amino group are preferred.

The amine salt compound is preferably a compound having at least one quaternary ammonium salt and at least one tertiary amino group.

Further, as the compound having two or more tertiary amino groups, 1,4-diazabicyclo [2.2.2]
Octane, 1,8-diazabicyclo [5.4.0] undec-7-ene, 1,5-diazabicyclo [4.3.
0] non-5-ene, 1,4-dimethylpiperazine, 4
-[2- (dimethylamino) ethyl] morpholine, N,
N, N ', N'-tetramethylethylenediamine, N,
N, N ', N'-tetramethyl-1,3-butanediamine, N, N, N', N'-tetramethyl-1,4-butanediamine, N, N, N ', N'-tetramethyl -1,
3-propanediamine, N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N',
N ', N "-pentamethyldiethylenetriamine, 1,
It is preferable to use one or more compounds selected from the group consisting of 1,3,3-tetramethylguanidine.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The requirements for constituting the present invention will be described below in order.

The polyamide reverse osmosis composite membrane according to the present invention comprises:
An aqueous solution containing a polyfunctional amine and an amine salt compound, and an amine-reactive compound having reactivity with an amino group selected from the group consisting of a polyfunctional acyl halide, a polyfunctional sulfonyl halide, and a polyfunctional isocyanate And a polyamide film formed on the porous support layer by reaction with an organic solution containing

In the present invention, a porous substrate is used as the support layer as described above. The pore size of the support layer needs to be large enough to allow purified water to sufficiently pass therethrough. However, when the thickness exceeds 300 nm, the thin film collapses in the air gap, making it difficult to obtain a flat membrane state. Desirably, it is 300 nm.

As the material of the porous support layer, a halogenated polymer such as polysulfone, polyethersulfone, polyimide, polyacrylonitrile, polypropylene, or polyvinylidene fluoride is preferably used.

The thickness of the porous support layer is from 25 to 1
It is preferably 25 μm, more preferably 40 to 75 μm.

It is preferable to use a polyfunctional amine having two or more amino groups (more preferably two to three amino groups). Further, the amino group is preferably a primary amino group or a secondary amino group (more preferably, a primary amino group).

As the polyfunctional amine, one kind or a mixture of two or more kinds is used. Examples thereof include aromatic primary diamines metaphenylenediamine, paraphenylenediamine,
Further, derivatives thereof include those containing a substituent such as an alkoxyl group such as a methoxy group or an ethoxy group, a hydroxyalkyl group, a hydroxyl group or a halogen atom. Also,
1,3-propanediamine and N-
Alkanediamine having an alkyl group and an N-aryl group, cycloaliphatic primary diamine
mine) cyclohexanediamine, piperazine and their alkyl derivatives, and other aromatic secondary diamines such as N, N'-dimethyl-1,3-phenylenediamine, N, N'-diphenylenediamine, benzidine, xylenediamine And their derivatives. Among them, the use of an aromatic primary diamine is preferred, and the use of metaphenylenediamine is most recommended.

The concentration of the polyfunctional amine is preferably 0.1 to 20% (more preferably 0.5 to 8%) in the aqueous solution. The pH of the aqueous solution is 7-1.
Preferably, it is adjusted to zero. At this time, a basic substance may be added to adjust the pH.
When an amine salt compound having an amino group capable of acting as an acceptor is present in an aqueous solution, it is not necessary to add a basic substance.

As the amine salt compound, a reaction product of a strong acid and a polyamine having a valency of 2 or more is used.
Add to 2%.

The above divalent or higher valent polyamine is preferably 2 or more 3
Compounds having a secondary amino group are preferred.

The compound having n or more tertiary amino groups (n is 2 or more, the same applies hereinafter) having two or more tertiary amino groups and the strong acid are in a molar ratio of 1: (1 or more and n or less). It is preferred to react with. More preferably 1: (1 or more,
0.95n or less), more preferably 1: (1 or more, 0.9
n or less).

It is preferable that only one amino group in the above-mentioned amine salt compound exists as a quaternary ammonium salt, and the other amino groups freely act as a base.

The reason why the reverse osmosis membrane according to the present invention can achieve a high permeation amount is considered as follows. That is, the quaternary ammonium salt in the amine salt compound acts as a pore-forming agent for the membrane, increases the amount of permeation, and forms a tertiary amino group of the acid generated during the interfacial reaction between the polyfunctional amine and the acid halide. Acts as a receptor. Due to the simultaneous action properties of such amine salt compounds,
It is considered that the use of the amine salt compound according to the present invention, which is partly a salt, forms a membrane having a higher permeation amount.

Examples of the compounds having two or more tertiary amino groups include 1,4-diazabicyclo [2.2.2] octane (DABCO) and 1,8-diazabicyclo [5.
4.0] undec-7-ene (DBU), 1,5-diazabicyclo [4.3.0] non-5-ene (DBN),
1,4-dimethylpiperazine, 4- [2- (dimethylamino) ethyl] morpholine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethyl-1,3 -Butanediamine, N, N, N ',
N'-tetramethyl-1,4-butanediamine (TMB
D), N, N, N ', N'-tetramethyl-1,3-propanediamine, N, N, N', N'-tetramethyl-
1,6-hexanediamine (TMHD), 1,1,3
3-tetramethylguanidine (TMGU), N, N,
N ', N', N "-pentamethyldiethylenetriamine, and mixtures thereof.

Examples of the strong acid include aromatic sulfonic acids such as toluenesulfonic acid (TSA) and benzenesulfonic acid (BSA), aliphatic sulfonic acids such as methanesulfonic acid (MSA) and ethanesulfonic acid (ESA), and camphorsulfonic acid. It is preferable to use an alicyclic sulfonic acid such as an acid (CSA), trifluoroacetic acid, nitric acid, hydrochloric acid, sulfuric acid or a mixture thereof.

Examples of the amino-reactive compounds include trimesic acid chloride (TMC), which is a di- or tricarboxylic acid halide, isophthalic acid chloride (IPC), terephthalic acid chloride (TPC), or a mixture thereof. The amine-reactive compound is contained in the organic solution in an amount of 0.0
It is preferable to adjust so as to be 1 to 10% (more preferably, 0.01 to 0.5%).

The organic solvent used in the present invention may be any organic solvent which is insoluble in water, such as hexane, cyclohexane, heptane, an alkane derivative having 8 to 12 carbon atoms, or a halogenated hydrocarbon such as freon. Is mentioned.

[0032]

The present invention will be described below in more detail with reference to examples and comparative examples. However, the following embodiments do not limit the present invention, and all modifications and implementations without departing from the spirit of the preceding and the following are included in the technical scope of the present invention.

<Production method> On the porous support layer described above,
The polyfunctional amine aqueous solution is applied by hand coating or a continuous process. After removing the excess polyfunctional amine aqueous solution on the porous support layer, an organic solution containing a polyfunctional acyl halide, polyfunctional sulfonyl halide or polyfunctional isocyanate is applied, and 5 seconds to 10 minutes, more preferably Performs a polymerization reaction for 20 seconds to 4 minutes. 50-1
After drying at 30 ° C. for 5 seconds to 20 minutes, more preferably about 4 minutes, the reverse osmosis membrane was obtained by washing with an aqueous alkaline solution in a temperature range of room temperature to 95 ° C. for 1 to 30 minutes.

<Performance Measurement Method> The amount of permeation was measured at 225 psig at 25 ° C. using a 2,000 ppm aqueous solution of sodium chloride (NaCl) as feed water. Also,
The salt removal rate was calculated by the following equation. Where R
Is the salt removal rate (%), C _f is the concentration of solute in feed water (% by weight), and C _p is the concentration of solute in permeate water (% by weight).

[0035]

(Equation 1)

Example 1 A polysulfone microporous substrate having a thickness of 140 μm was prepared by adding 2% metaphenylenediamine,
% DABCO and 0.85% MSA in aqueous solution
After immersion for 0 seconds to remove excess aqueous solution on the surface,
The reaction was carried out by immersing in a 0.1% trimesic acid chloride solution for 1 minute to obtain a composite membrane.

The thus obtained composite membrane was dried at 90 ° C. for 3.5 minutes, and then 0.2% Na ₂ CO _{3 at} 60 ° C.
The reverse osmosis membrane was obtained by sufficiently washing with an aqueous solution and further with distilled water.

As a result of measuring physical properties of the obtained reverse osmosis membrane,
The salt removal rate was 97%, and the permeation amount was 32.3 gfd.

Example 2 Except that an aqueous solution containing 2% metaphenylenediamine, 2% DABCO and 1.7% MSA was used as a polyfunctional amine aqueous solution.
This was performed in the same manner as in Example 1. The physical properties of the obtained film were measured in the same manner as in Example 1. As a result, the salt removal rate was 96.
7%, the permeation amount was 28.4 gfd.

<Examples 3 to 23 and Comparative Example A>
The procedure was performed in the same manner as in Example 1 except that an aqueous polyfunctional amine solution having the composition shown in Table 1 was used, and the physical properties of the obtained film were measured in the same manner as in Example 1. Table 1 also shows the measurement results.

[0041]

[Table 1]

[0042]

Industrial Applicability The present invention is constituted as described above and comprises a polyfunctional compound in which an amine salt compound obtained by reacting a strong acid with a polyamine having a valency of 2 or more is added in an aqueous solution to a concentration of 0.1 to 12%. By using the aqueous amine solution for interfacial polymerization with an amine-reactive compound, a polyamide reverse osmosis composite membrane having a higher permeation amount and excellent performance could be obtained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor De Wooim South Korea Seoul, Gangnam-uk, Apgujeong-dong, 513 Hanyang apartment. , 51-107 (72) Inventor Song Shik Kim Seoul, Song Park, Oran Dong, Olympic Apartment. , 101-1301 (72) Inventor Yang Seo Yun Seoul, Gangnam-ku, Gepo-dong, Hyundai apartment. , 103-605 F term (reference) 4D006 GA03 MA03 MA07 MA22 MA31 MB02 MB06 MC23 MC29 MC54 MC56X MC58 MC62X MC63 MC78X NA41 NA46 NA54 PA01 PB03 PB04 PB05

Claims (5)

[Claims] An aqueous solution containing a polyfunctional amine and an amine salt compound and an amino group selected from the group consisting of a polyfunctional acyl halide, a polyfunctional sulfonyl halide, and a polyfunctional isocyanate. In the production of a composite membrane for forming a polyamide membrane on a porous support layer by reacting with an organic solution containing an amine-reactive compound having, the amine salt compound is obtained by reacting a strong acid with a diamine or higher polyamine. A method for producing a polyamide reverse osmosis composite membrane, wherein the amine salt compound is added to the aqueous solution so as to have a concentration of 0.1 to 12% (weight%, the same applies hereinafter). 2. The reverse polyamide according to claim 1, wherein the strong acid is an acid selected from the group consisting of aromatic sulfonic acid, aliphatic sulfonic acid, alicyclic sulfonic acid, trifluoroacetic acid, nitric acid, and hydrochloric acid. A method for producing an osmotic composite membrane. 3. The method for producing a polyamide reverse osmosis composite membrane according to claim 1, wherein the diamine or higher polyamine is a compound having two or more tertiary amino groups. 4. The polyamide reverse osmosis composite membrane according to claim 1, wherein the amine salt compound is a compound having at least one quaternary ammonium salt and at least one tertiary amino group. Manufacturing method. 5. The compound having two or more tertiary amino groups is 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] undeca-.
7-ene, 1,5-diazabicyclo [4.3.0] non-5-ene, 1,4-dimethylpiperazine, 4- [2-
(Dimethylamino) ethyl] morpholine, N, N,
N ′, N′-tetramethylethylenediamine, N, N,
N ′, N′-tetramethyl-1,3-butanediamine,
N, N, N ', N'-tetramethyl-1,4-butanediamine, N, N, N', N'-tetramethyl-1,3-
Propanediamine, N, N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N', N ',
N "-pentamethyldiethylenetriamine, 1,1,
The method for producing a polyamide reverse osmosis composite membrane according to claim 3, which is at least one compound selected from the group consisting of 3,3-tetramethylguanidine.