JP2006021094A - Compound semi-permeable membrane and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound semi-permeable membrane having high solute-removing performance, water permeability and durability and a simple method of manufacturing a compound semi-permeable membrane permitting the production of a membrane having a high removal rate of ions and neutral molecules, a compound semi-permeable membrane separating specified ions selectively, etc. <P>SOLUTION: The simple method comprises the production of a compound semi-permeable membrane by forming a polyamide layer having a separating function and composed of a multifunctional amine compound and a multifunctional acid halide on a micro-porous supporting film and subjecting the semi-permeable membrane to such a simple method as bringing the semi-permeable membrane with a reagent reacting with a primary amino group to form a diazonium salt or a derivative of the salt or using a hydrazine as a multifunctional amine and treating with an oxidizing agent in order to obtain a membrane having a high removal rate of ions or neutral molecules, a compound semi-permeable membrane separating specified ions selectively, etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-performance composite semipermeable membrane and a method for producing the same, and more particularly, to a high-performance composite semipermeable membrane for selectively permeating and separating components of an aqueous solution in which a plurality of salts and organic substances are mixed. It relates to the manufacturing method.

  Regarding the separation of a mixture, there are various techniques for removing substances (for example, salts) dissolved in a solvent (for example, water). In recent years, membrane separation methods have been used as processes for saving energy and resources. ing. Examples of membranes used in the membrane separation method include microfiltration membranes, ultrafiltration membranes, and reverse osmosis membranes. Furthermore, in recent years, a membrane (loose RO membrane or NF membrane: nanofiltration membrane) located between a reverse osmosis membrane and an ultrafiltration membrane has also appeared and has been used. This technology can be used to obtain drinking water from, for example, seawater, canned water, and water containing harmful substances, and has also been used for the production of industrial ultrapure water, wastewater treatment, recovery of valuable materials, and the like. It was.

Most of the composite semipermeable membranes currently on the market have an active layer obtained by crosslinking a gel layer and a polymer on a microporous support membrane, and an active layer obtained by polycondensing monomers on the microporous support membrane. There are two types. Above all, the composite semipermeable membrane formed by coating a microporous support membrane with an ultra-thin film layer made of crosslinked polyamide obtained by polycondensation reaction of polyfunctional amine and polyfunctional acid halide has permeability and selective separation. Widely used as a high reverse osmosis membrane. Currently, it is used in various applications, and a method for easily making a film suitable for each application is desired. As a method for easily changing the performance of the membrane, for example, Patent Document 1 describes a post-treatment method using nitrous acid, and Patent Document 2 describes a post-treatment method using chlorine.
JP 63-175604 (Claims) JP 63-54905 A (Claims)

  However, the films of Patent Document 1 and Patent Document 2 are not easy methods for obtaining a film having a higher neutral molecule removal rate than the ion removal rate and a film having a characteristic of selectively separating specific ions.

  Therefore, the present invention provides a composite semipermeable membrane having high solute removal properties, high water permeability, and high durability, and at the same time, a method for producing a composite semipermeable membrane having various characteristics by a simple method. It is intended to provide. For example, an object of the present invention is to provide a composite semipermeable membrane having high monovalent cation exclusion performance and high water permeability and appropriately transmitting polyvalent cations.

In order to solve this problem, the present invention has the following configuration. That is,
(1) A composite semipermeable membrane, wherein a polyamide separation functional layer comprising a polyfunctional amine compound and a polyfunctional acid halide is formed on a microporous support membrane, and the polyamide and iodine are bonded to each other. .

  (2) A composite semipermeable membrane having a separation functional layer containing a primary amino group is contacted with a reagent that reacts with the primary amino group to produce a diazonium salt or a derivative thereof, and then reacts with the diazonium salt. A method for treating a composite semipermeable membrane, which comprises contacting with a chemical reagent.

  (3) The method for treating a composite semipermeable membrane according to (1), wherein the reagent that reacts with the primary amino group to produce a diazonium salt or a derivative thereof is an aqueous solution containing nitrous acid and / or a salt thereof.

  (4) The method for treating a composite semipermeable membrane according to (2) or (3), wherein the reactive reagent with the diazonium salt is iodide ion.

  (5) The method for treating a composite semipermeable membrane according to (2) or (3), wherein the reactive reagent with the diazonium salt is sulfite ion or hydrogen sulfite ion.

(6) In a composite semipermeable membrane comprising a thin film and a microporous support that supports the thin film, the thin film has a polyfunctional amine compound having two or more reactive amino groups and two or more reactivity. A polyamide-based skin layer obtained by polycondensation reaction with a polyfunctional acid halogen compound having an acid halide group, and 2000 ppm of sodium chloride at an operating pressure of 0.5 MPa and a temperature of 25 ° C. for the composite semipermeable membrane. The performance when evaluated with an aqueous solution containing pH 6.5 is that the rejection rate of sodium chloride is 90% or more, the amount of permeated water is 1.0 m ³ / m ² · day or more, and the operation of the composite semipermeable membrane The performance when evaluated with an aqueous solution of pH 6.5 containing 2000 ppm of calcium chloride at a pressure of 0.5 MPa and a temperature of 25 ° C. is characterized in that the calcium chloride rejection is 80% or less. Permeable membrane.

(7) The composite semipermeable membrane according to (6), wherein the permeated water amount is 1.15 m ³ / m ² · day or more.

(8) The composite semipermeable membrane according to (6) or (7), wherein the compound having two or more reactive amino groups is hydrazines.
(9) A method for producing a composite semipermeable membrane in which a polyfunctional amine compound and a polyfunctional acid halide are polycondensed to form a crosslinked polyamide membrane on a porous support membrane, wherein the polyfunctional amine compound comprises hydrazine A method for producing a composite semipermeable membrane, characterized by containing 0.1 to 0.3 in molar ratio.

(10) A method for producing a composite semipermeable membrane, comprising treating the composite semipermeable membrane produced according to the method of (9) with an oxidizing agent.
It is.

  According to the present invention, it is possible to convert the characteristics of a composite semipermeable membrane having both high water permeability and high solute removal by a simple method, that is, to change the selective separation characteristics of solutes.

  As one aspect of the composite semipermeable membrane of the present invention, a separation functional layer having substantially separation performance is coated on a porous support membrane having substantially no separation performance, preferably the separation function. The layer is made of a crosslinked polyamide obtained by the reaction of a polyfunctional amine and a polyfunctional acid halide. Here, the polyfunctional amine comprises at least one component of an aliphatic polyfunctional amine and an aromatic polyfunctional amine.

  The aliphatic polyfunctional amine is an aliphatic amine having two or more amino groups in one molecule, and is preferably a piperazine-based amine and a derivative thereof. For example, piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2- Examples thereof include n-propylpiperazine and 2,5-di-n-butylpiperazine, and piperazine and 2,5-dimethylpiperazine are particularly preferable from the viewpoint of stability of performance.

  The aromatic polyfunctional amine is an aromatic amine having two or more amino groups in one molecule, and is not particularly limited, but includes metaphenylene diamine, paraphenylene diamine, 1, 3, 5 -Triaminobenzene and the like, and N-alkylated products thereof include N, N-dimethylmetaphenylenediamine, N, N-diethylmetaphenylenediamine, N, N-dimethylparaphenylenediamine, N, N-diethylparaphenylenediamine, etc. In view of the stability of performance, metaphenylenediamine and 1,3,5-triaminobenzene are particularly preferable.

  These amines may be used alone, but are preferably mixed and used.

  The polyfunctional acid halide is an acid halide having two or more carbonyl halide groups in one molecule, and is not particularly limited as long as it gives a polyamide by reaction with the amine. Examples of the polyfunctional acid halide include oxalic acid, malonic acid, maleic acid, fumaric acid, glutaric acid, 1,3,5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid. 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, and acid halides of 1,4-benzenedicarboxylic acid can be used. Among acid halides, acid chlorides are preferred, and are acid halides of 1,3,5-benzenetricarboxylic acid, particularly in terms of economy, availability, ease of handling, and ease of reactivity. Trimesic acid chloride is preferred. Although the said polyfunctional acid halide can also be used independently, you may use it as a mixture.

  The organic solvent that dissolves the polyfunctional acid halide is not miscible with water, and preferably does not destroy the porous support membrane, and may be any as long as it does not inhibit the formation reaction of the crosslinked polyamide. . Typical examples include halogenated hydrocarbons such as liquid hydrocarbons and trichlorotrifluoroethane, but they are substances that do not destroy the ozone layer, are easily available, are easy to handle, and are safe for handling. In consideration of the properties, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, heptadecane, hexadecane, etc., and simple substances such as cyclooctane, ethylcyclohexane, 1-octene, 1-decene, or a mixture thereof are preferably used.

  Next, the preferable manufacturing method of a composite semipermeable membrane is demonstrated. The separation functional layer having substantially separation performance in the composite semipermeable membrane is, for example, an aqueous solution containing the above-mentioned polyfunctional amine and an organic material immiscible with water containing the above-mentioned polyfunctional acid halide. It forms by making it react on the below-mentioned porous support membrane using a solvent solution.

  Here, the concentration of the aqueous solution containing the polyfunctional amine is preferably 0.1 to 20% by weight, more preferably 0.5 to 15% by weight.

  In the case of an aqueous solution containing a polyfunctional amine or an organic solvent solution containing a polyfunctional acid halide, an acylation catalyst, a polar solvent, an acid scavenger may be used as long as it does not interfere with the reaction between the two components. In addition, compounds such as surfactants and antioxidants may be contained.

  In the present invention, the porous support membrane is used to support a separation functional layer such as a crosslinked polyamide. Although the structure of a porous support membrane is not specifically limited, As a preferable porous support membrane, the polysulfone support membrane reinforced with the cloth etc. can be illustrated. The pore diameter and the number of pores of the porous support membrane are not particularly limited, but it has uniform fine pores or gradually large pores from one side to the other side, and the size of the fine pores is the size of one side. A support film having a structure in which the surface of the film is 100 nm or less is preferable.

  The porous support membrane used in the present invention can be selected from various commercially available materials such as “Millipore Filter VSWP” (trade name) manufactured by Millipore and “Ultra Filter UK10” (trade name) manufactured by Toyo Roshi Kaisha. “Office of Saleen Water Research and Development Progress Report” No. 359 (1968).

  The material used for the porous support membrane is not particularly limited. For example, polysulfone, cellulose acetate, cellulose nitrate, polyvinyl chloride, or other homopolymers or blended materials can be used, but chemically, mechanically, and thermally. It is preferable to use polysulfone having high stability. Specifically, a polysulfone dimethylformamide (hereinafter referred to as DMF) solution is applied to a polyester fabric or non-woven fabric which is densely woven to a substantially constant thickness, and wet coagulated in an aqueous solution containing 2% by weight of DMF. Thus, it is possible to obtain a suitable porous support membrane in which most of the surface has fine pores having a diameter of several tens of nm or less.

  The surface of the porous support membrane may be coated with an aqueous solution containing a polyfunctional amine as long as the aqueous solution is uniformly and continuously coated on the surface. For example, the coating may be carried out by a method of coating a porous support membrane in the aqueous solution. Next, the excessively applied aqueous solution is removed by a liquid draining step. As a method for draining liquid, for example, there is a method in which the film surface is allowed to flow naturally while being held in a vertical direction. After draining, the membrane surface may be dried to remove all or part of the water in the aqueous solution. Thereafter, the organic solvent solution containing the polyfunctional acid halide is applied to the porous support membrane coated with the aqueous solution containing the polyfunctional amine, and a separation functional layer of the crosslinked polyamide is formed by reaction.

  The concentration of the polyfunctional acid halide is not particularly limited, but if it is too small, the formation of the separation functional layer, which is an active layer, may become a disadvantage, and if it is too large, it will be disadvantageous in terms of cost. Among these, about 0.01 to 1.0% by weight is preferable. The removal of the organic solvent after the reaction can be performed, for example, by the method described in JP-A-5-76740.

  The composite semipermeable membrane thus obtained can be used as it is, but it is preferable to remove unreacted residues by washing before use. It is preferable to wash the membrane with water in the range of 30 to 100 ° C. to remove the remaining amino compound and the like. The washing can be performed by immersing the support membrane in water within the above temperature range or spraying water. When the temperature of the water used is less than 30 ° C., the amino compound remains in the composite semipermeable membrane and the amount of permeated water tends to be low. Further, when washing is performed at a temperature exceeding 100 ° C. with an autoclave, steam, or the like, the membrane may cause thermal shrinkage, and the amount of permeated water tends to be low. Furthermore, it is preferable to perform various post-treatments thereafter.

  Then, the composite semipermeable membrane produced by the above-described method is brought into contact with a reagent that reacts with a primary amino group to produce a diazonium salt or a derivative thereof to produce a diazonium salt or a derivative thereof. Various functional groups can be introduced into the film by contacting with a reactive reagent with the diazonium salt in the presence of the diazonium salt. The method of bringing the reagent into contact with the composite semipermeable membrane is not particularly limited. For example, a method of immersing the entire composite semipermeable membrane in the reagent or a method of spraying the reagent may be used. If so, the method is not limited.

Examples of the reagent that reacts with a primary amino group to produce a diazonium salt or a derivative thereof according to the present invention include aqueous solutions of nitrous acid and salts thereof, nitrosyl compounds, and the like. Since an aqueous solution of nitrous acid or a nitrosyl compound easily generates gas and decomposes, it is preferable to sequentially generate nitrous acid by, for example, a reaction between nitrite and an acidic solution. In general, nitrite reacts with hydrogen ions to produce nitrous acid (HNO ₂ ), but it is efficiently produced at 20 ° C. when the pH of the aqueous solution is 7 or less, preferably 5 or less, more preferably 4 or less. Among these, an aqueous solution of sodium nitrite reacted with hydrochloric acid or sulfuric acid in an aqueous solution is particularly preferable because of easy handling.

  In the present invention, the concentration of nitrous acid or nitrite in the reagent that reacts with the primary amino group to produce a diazonium salt or a derivative thereof is preferably in the range of 0.01 to 1% by weight at 20 ° C. . If the concentration is lower than 0.01%, a sufficient effect cannot be obtained. If the concentration of nitrous acid and nitrite is higher than 1%, handling of the solution becomes difficult.

  The temperature of the nitrous acid aqueous solution is preferably 15 ° C to 45 ° C. If the temperature is lower than this, the reaction takes time, and if it is 45 ° C. or higher, the decomposition of nitrous acid is quick and difficult to handle.

  The contact time with the nitrous acid aqueous solution may be a time for forming a diazonium salt. A high concentration can be processed in a short time, but a low concentration requires a long time. When the diazonium salt is formed at a low concentration over a long period of time, the diazonium salt reacts with water before reacting with the reactive reagent with the diazonium salt, so it is desirable to perform the treatment at a high concentration for a short time. For example, a 1000 mg / l nitrous acid aqueous solution is preferably 30 seconds to 1 hour.

  After forming the diazonium salt, it is possible to change the characteristics of the film in various ways by reacting with a reactive reagent with the diazonium salt. The reactive reagent used here is chloride ion, bromide ion, cyanide ion, iodide ion, boron fluoride, hypophosphorous acid, sodium hydrogen sulfite, sulfite ion, aromatic amine, hydrogen sulfide, thiocyanic acid. Etc. Chloride ions, bromide ions, and cyanide ions have low reactivity as they are, and it is necessary to coexist with copper chloride. For example, when a reducing agent such as hypophosphorous acid is used, the amino group can be replaced with hydrogen. By using an aromatic amine, a diazo coupling reaction occurs and it is possible to introduce an aromatic amine into the film surface. Preferred are iodide ion, sodium hydrogen sulfite, and sulfite ion. When reacted with iodide ions, a substitution reaction occurs instantaneously and the amino group is substituted with iodine. When reacted with sodium hydrogen sulfite, a substitution reaction occurs instantaneously and the amino group is substituted with a sulfo group.

  As another aspect of the present invention, a composite semipermeable membrane produced by the above-described method, preferably a composite semipermeable membrane containing hydrazines as an amine component, is subjected to nitrous acid treatment, for example, at a pH of 6 to 6. It is preferable to contact the chlorine-containing aqueous solution in the range of 13 at normal pressure to increase the membrane rejection and water permeability.

And according to the present invention, the performance when evaluated with an aqueous solution having a pH of 6.5 containing sodium chloride of 2000 ppm at an operating pressure of 0.5 MPa and a temperature of 25 ° C. has a sodium chloride exclusion rate of 90% or more, and the amount of permeated water The performance when evaluated with an aqueous solution of pH 6.5 containing 2000 ppm of calcium chloride at an operating pressure of 0.5 MPa and a temperature of 25 ° C. is 1.0 m ³ / m ² · day or more. A composite semipermeable membrane characterized by being 80% or less can be obtained. More preferably, the amount of permeated water is 1.15 m ³ / m ² · day or more.

  Examples of hydrazines include hydrazine, phthalic dihydrazide, naphthalenedicarboxylic acid dihydrazide, hydroxyisophthalic acid dihydrazide, dimethylterephthalic acid dihydrazide, biphenyldicarboxylic acid dihydrazide, benzophenone dicarboxylic acid dihydrazide, diphenyl ether dicarboxylic acid dihydrazide, diphenylsulfone dicarboxylic acid dihydrazide, Examples include lidene diphthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, and 2,6-naphthalenedicarboxylic acid dihydrazide.

Hydrazines are preferably used together with polyfunctional amine compounds, and are preferably contained in a molar ratio of 0.1 to 0.3. If it is 0.1 or less, the amount of permeate is not sufficient, and if it is 0.3 or more, the rejection rate is too low.
Further, a membrane containing hydrazine greatly increases the amount of permeated water when treated with an oxidizing agent. As the oxidizing agent, chlorine or an aqueous sodium hypochlorite solution is preferably used.

  Using the composite semipermeable membrane obtained by the production method of the present invention, for example, removing harmful substances such as inorganic substances and organic substances and precursors thereof contained in raw water at an operating pressure of 0.1 to 3.0 MPa Can do.

Here, if the operating pressure is lowered, the capacity of the pump to be used is reduced and the power cost is reduced. Conversely, if the operating pressure is increased, the power cost increases for the reasons described above, and the amount of permeated water tends to increase. On the other hand, if the amount of permeated water is too high, clogging due to fouling of the membrane surface may occur. And the cost is high. Therefore, in order to carry out stable operation at a reduced cost, the operating pressure is preferably in the range of 0.1 to 3.0 MPa, more preferably 0.1 to 2.0 MPa, and still more preferably 0.1 to 3.0 MPa. Within the range of 1.0 MPa. For the same reason, it is preferable that the permeated water amount be in the range of 0.5 to 5.0 m ³ / m ² · day, more preferably 0.6 to 3.0 m ³ / m ² · day. More preferably, it is in the range of 0.8 to 2.0 m ³ / m ² · day.

  Further, in order to efficiently treat the supplied water and reduce the water production cost, the ratio of the permeated water amount to the raw water supply amount, that is, the recovery rate is preferably 80% or more, more preferably 85% or more, and further 90% or more good. However, if it exceeds 99.5%, clogging due to fouling of the film surface may occur, so it is preferable not to exceed 99.5%.

  In the present invention, the form of the composite semipermeable membrane is not limited and may be a hollow fiber membrane or a flat membrane. The modified composite semipermeable membrane obtained by the present invention forms elements and modules when used for liquid separation, but the form thereof is not particularly limited, such as a module type or a spiral type.

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 Examples and Comparative Examples, membrane evaluation was performed by evaluating the amount of permeated water when filtered for 3 hours using a sodium chloride aqueous solution having a temperature of 25 ° C., pH 6.5, and a concentration of 2000 mg / l under an operating pressure of 0.5 MPa. Thereafter, a 2000 mg / l calcium chloride aqueous solution was similarly evaluated.
The amount of permeated water was determined by the amount of water permeating the membrane per unit area (m ² ) per unit time (day).
In the examples, the removal rate was determined by the following equation.

Removal rate (%) = {1- (solute concentration in permeate) / (solute concentration in feed solution)} × 100.
The amount of permeated water was determined as the amount of permeated water per unit area (m ² ) per unit time (day) (m ³ / m ² · day).

<Example 1>
A fabric-reinforced polysulfone support membrane (ultrafiltration membrane), which is a porous support membrane, was produced by the following method. That is, a wet non-woven fabric of polyester fiber having a single yarn fineness of 0.5 and 1.5 dtex, an air permeability of 0.7 cm ³ / cm ² · sec, an average pore diameter of 7 μm or less, a length of 30 cm and a width of 20 cm Was fixed on a glass plate, and a solution of dimethylformamide (DMF) solvent in a polysulfone concentration of 15% by weight (2.5 poise: 20 ° C.) was cast to a total thickness of 200 μm, and immediately poured into water. A porous support membrane of polysulfone was obtained by immersion (this is referred to as a PS support membrane).

Next, this porous support membrane was immersed in an aqueous solution of 1.25% by weight of m-phenylenediamine and 2.0% by weight of ε-caprolactam for 2 minutes, and then dissolved in decane so that the trimesic acid chloride was 0.06% by weight. The solution thus prepared was applied at a rate of 160 cm ³ / m ² . Next, after removing the excess solution by removing the excess solution with the film vertical, in order to evaporate the solvent remaining on the film surface, the temperature of 30 ° C. is set so that the wind speed on the film surface is 8 m / s. After blowing air for 1 minute, the remaining acid halide groups were hydrolyzed with a 1% aqueous Na ₂ CO ₃ solution. Thereafter, it was immersed in hot water at 90 ° C. for 2 minutes to obtain a composite semipermeable membrane.

  This membrane was immersed in a 5000 mg / l aqueous sodium nitrite solution adjusted to pH 2 with sulfuric acid at 30 ° C. for 40 seconds. Thereafter, it was immersed in a 1 wt% potassium iodide aqueous solution for 15 hours. The membrane performance is shown in Table 1.

<Example 2>
A film was prepared in the same manner as in Example 1 except that the film was immersed in a 0.1 wt% sodium hydrogen sulfite aqueous solution instead of the potassium iodide aqueous solution.

<Comparative Example 1>
A membrane was prepared in the same manner as in Example 1 except that it was immersed in distilled water instead of the potassium iodide aqueous solution.

<Example 3>
The porous support membrane described in Example 1 was immersed in an aqueous solution of 1.25% by weight of m-phenylenediamine, 2.0% by weight of ε-caprolactam, and 0.125% by weight of hydrazine (molar ratio to mPDA 0.27) for 2 minutes. A solution obtained by dissolving trimesic acid chloride in decane so as to be 0.06 wt% was applied at a rate of 160 cm ³ / m ² . Next, after removing the excess solution by removing the excess solution with the film vertical, in order to evaporate the solvent remaining on the film surface, the temperature of 30 ° C. is set so that the wind speed on the film surface is 8 m / s. After blowing air for 1 minute, the remaining acid halide groups were hydrolyzed with a 1% aqueous Na ₂ CO ₃ solution. Then, after being immersed in hot water at 90 ° C. for 2 minutes, in order to improve the membrane performance, immersed in a solution containing 500 ppm of sodium hypochlorite adjusted to pH 7 for 2 minutes, immersed in an aqueous solution of 1000 ppm sodium hydrogen sulfite, and then remaining Sodium chlorite was eliminated to obtain a composite semipermeable membrane.
The obtained composite semipermeable membrane was evaluated under the above conditions, and the salt rejection and the amount of permeated water were measured. The evaluation results are shown in Table 2.

<Example 4>
Film formation and evaluation were performed in the same manner as in Example 3 except that the hydrazine concentration was 0.06 wt%. The evaluation results are shown in Table 2.

<Comparative example 2>
Film formation and evaluation were performed in the same manner as in Example 3 except that hydrazine was not added. The evaluation results are shown in Table 2.

Claims (10)

A composite semipermeable membrane comprising a polyamide separation functional layer comprising a polyfunctional amine compound and a polyfunctional acid halide on a microporous support membrane, wherein the polyamide and iodine are bonded. A composite semipermeable membrane having a separation functional layer containing a primary amino group is contacted with a reagent that reacts with the primary amino group to produce a diazonium salt or a derivative thereof, and then a reactive reagent with the diazonium salt A method for treating a composite semipermeable membrane, comprising contacting the membrane. The method for treating a composite semipermeable membrane according to claim 2, wherein the reagent that reacts with the primary amino group to produce a diazonium salt or a derivative thereof is an aqueous solution containing nitrous acid and / or a salt thereof. The method for treating a composite semipermeable membrane according to claim 2 or 3, wherein the reactive reagent with the diazonium salt is iodide ion. The method for treating a composite semipermeable membrane according to claim 2 or 3, wherein the reactive reagent with the diazonium salt is sulfite ion or bisulfite ion. A composite semipermeable membrane comprising a thin film and a microporous support for supporting the same, wherein the thin film is a polyfunctional amine compound having two or more reactive amino groups and two or more reactive acid halides A polyamide-based skin layer obtained by polycondensation reaction with a polyfunctional acid halogen compound having a group, pH 6 containing 2000 ppm of sodium chloride at an operating pressure of 0.5 MPa and a temperature of 25 ° C. of the composite semipermeable membrane. The performance when evaluated with an aqueous solution of 0.5 is that the rejection rate of sodium chloride is 90% or more, the amount of permeated water is 1.0 m ³ / m ² · day or more, and the operating pressure of the composite semipermeable membrane is 0. A composite semipermeable membrane characterized by having a calcium chloride exclusion rate of 80% or less when evaluated with an aqueous solution having a pH of 6.5 containing 2,000 ppm of calcium chloride at 5 MPa and a temperature of 25 ° C. The composite semipermeable membrane according to claim 6, wherein the permeated water amount is 1.15 m ³ / m ² · day or more. The composite semipermeable membrane according to claim 6 or 7, wherein the compound having two or more reactive amino groups is hydrazines. A method for producing a composite semipermeable membrane in which a polyfunctional amine compound and a polyfunctional acid halide are polycondensed to form a crosslinked polyamide membrane on a porous support membrane, wherein the polyfunctional amine compound contains hydrazine in a molar form. The manufacturing method of the composite semipermeable membrane characterized by containing 0.1-0.3 in ratio. A method for producing a composite semipermeable membrane, comprising treating the composite semipermeable membrane produced according to the method of claim 9 with an oxidizing agent.