JP2000033243A - Composite semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite semipermeable membrane which can selectively remove contaminants and a trace amount of harmful substances contained in raw water and be operated in a high recovery ratio. SOLUTION: In a semipermeable membrane in which a separation function layer of a crosslinked polyamide obtained by the reaction of mixed amine components of an aliphatic polyfunctional amine and an aromatic polyfunctional amine, a polyfunctional acid halide, and a polyfunctional acid anhydride halide is formed on a porous support membrane, the molar ratio of the polyfunctional acid halide to the polyfunctional acid anhydride halide is 80/20-10/90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high-performance composite semipermeable membrane for selectively permeating and separating components of a liquid mixture, a method for producing the same, and a method for removing harmful substances using the same.

[0002]

2. Description of the Related Art With respect to separation of a mixture, there are various techniques for removing substances (for example, salts) dissolved in a solvent (for example, water). In recent years, however, membrane separation has been carried out as a process for saving energy and resources. The law is being used. The membrane used for the membrane separation method includes a microfiltration membrane,
There are ultrafiltration membranes and reverse osmosis membranes. More recently, a membrane located between a reverse osmosis membrane and an ultrafiltration membrane (loose RO membrane or NF membrane: Nanofiltration mem)
(brane) has also appeared and been used. This technology can be used, for example, to obtain drinking water from seawater, can water, and water containing harmful substances, and is also used for the production of industrial ultrapure water, wastewater treatment, and recovery of valuable resources. I have been.

Most of currently available composite semipermeable membranes have a porous support membrane having a gel layer and an active layer obtained by crosslinking a polymer, and a porous support membrane having an active layer obtained by polycondensation of a monomer on a porous support membrane. It has two types. Among them, a composite semipermeable membrane comprising a porous support membrane coated with a separation functional layer made of a crosslinked polyamide obtained by a polycondensation reaction between a polyfunctional amine and a polyfunctional acid halide has a permeability and a selective separation property. Widely used as high reverse osmosis membrane.

However, the demand for a practical semipermeable membrane for reverse osmosis has been increasing year by year, and from the viewpoint of energy saving, a semipermeable membrane having high water permeability and capable of operating at a lower pressure while maintaining high solute removal properties. Appearance is desired. On the other hand, a high-recovery operation is also desired. However, when a high-recovery operation is performed using a membrane having a high silica removal rate, the concentration of silica on the concentrated water side rapidly increases and precipitates on the membrane surface. As a result, there is a problem that the membrane performance is lowered and stable operation and improvement of water quality cannot be expected.

[0005] In recent years, in a water treatment plant using raw water such as river water and lake water, carcinogenicity is caused by chlorine disinfection treatment of soluble organic matter (trihalomethane precursor) flowing from peat lands or mountainous areas. The generation of halogen-containing organic substances (trihalomethanes) having the following has become a serious problem. The most important of the trihalomethane precursors is humic acid, a soluble organic substance having a molecular weight of thousands to tens of thousands. At present, the removal rate at the start of operation is high in the ozone / activated carbon treatment method that is being considered for introduction into a water purification plant, but after long-term operation, adsorption occurs in the pores of activated carbon and the removal rate drops sharply. Cannot be removed. For this reason, there is a problem that the exchange of the activated carbon is required frequently and the cost is increased. Further, in a biological treatment method such as a catalytic oxidation method and a biofilm method, there is a problem that soluble organic substances are generated after metabolism of a living organism and cannot be sufficiently removed. In the membrane separation method, the microfiltration membrane and the ultrafiltration membrane have a large pore size, and cannot sufficiently remove humic acid. In the reverse osmosis membrane, the pore diameter is small and the humic acid removal rate is high, but the silica removal rate is also high. As a result, there is a problem that it is difficult to operate at a high recovery rate using the reverse osmosis membrane.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a composite semipermeable membrane having high solute removal and high water permeability and capable of operating at a high recovery rate. The purpose is to do.

[0007]

In order to achieve the above object, the present invention takes the following measures. (1) "Crosslinked polyamide formed by reacting a mixture of a polyfunctional acid halide and a polyfunctional acid anhydride halide with a mixed amine of an aliphatic polyfunctional amine and an aromatic polyfunctional amine on a porous support membrane Wherein the molar ratio between the polyfunctional acid halide and the polyfunctional acid anhydride halide is in the range of 80/20 to 10/90. (2) "the sum of the hydrophilic group concentrations in the separation functional layer analyzed by X-ray photoelectron spectroscopy (ESCA) is in the range of 0.001 or more and less than 0.1, and the separation functional layer is Wherein the thickness of the composite semi-permeable membrane is in the range of 1 to 500 nm. (3) "The hydrophilic group is selected from the group consisting of an amino group, a hydroxyl group, a carbonyl group and a sulfo group." At least one group and a carboxyl group And the composite semipermeable membrane according to the above (1) or (2). ”(4) Any one of the above (1) to (3), wherein the aliphatic polyfunctional amine is a compound represented by the following formula: Described above. "

[0008]

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R1 to R8: H, OH, COOH, SO ₃
H, NH ₂ or a hydrocarbon group (5) “the aromatic polyfunctional amine is at least selected from the group consisting of metaphenylenediamine, paraphenylenediamine, 1,3,5-triaminobenzene and N-alkylated products thereof (1) above, which is one compound
The composite semipermeable membrane according to any one of (1) to (4). (6) The composite according to any one of the above (1) to (5), wherein the molar ratio between the aliphatic polyfunctional amine and the aromatic polyfunctional amine is in the range of 40/60 to 95/5. (7) The above (1) to (6), wherein the polyfunctional acid halide is a polyfunctional acid chloride and the polyfunctional acid anhydride halide is a compound represented by the following formula. The composite semipermeable membrane according to any one of the above).

[0010]

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X1, X2: aliphatic group having 1 to 6 carbon atoms, H, OH, COOH, SO ₃ H, COF, COC
1, COBr or COI or an acid anhydride group to which they are bonded X3: an aliphatic group having 1 to 6 carbon atoms, H, OH, C
OOH, SO ₃ H, COF, COCl, COBr or COI Y: F, Cl, Br or I (8) “A method according to any one of (1) to (7) above, wherein the porous support membrane contains polysulfone. (9) “Temperature is 25 ° C., pH is 6.5, and silica concentration is 3
An aqueous solution having a concentration of 0 ppm and a humic acid concentration of 2 ppm was subjected to a pressure of 0.
The silica transmittance when permeated at 3 MPa for 3 hours is in the range of 55 to 90%, and the humic acid removal rate is 98%.
And the amount of permeated water is 0.8 to 3.0 m ³ / m ²
-The composite semipermeable membrane according to any one of (1) to (8) above, which is in the range of d. (10) "A fresh water producing method characterized by removing harmful substances and their precursors contained in water using the composite semipermeable membrane according to any one of the above (1) to (9)." (11) “The method for producing fresh water according to the above (10), wherein the harmful substance is trihalomethane.” (12) The above (1) wherein the water recovery is 80% or more.
0) or the method for producing fresh water according to (11). (13) "Rough filtration means for roughly filtering raw water;
A desalination apparatus, comprising: a membrane filtration unit configured to perform filtration using the composite semipermeable membrane according to any one of (9) to (9). (14) "The fresh water generator according to the above (13), comprising an ultrafiltration means using an ultrafiltration membrane between the coarse filtration means and the membrane filtration means." (15) "Coarse" The fresh water generator according to the above (13) or (14), wherein the filtration means comprises a means for adding a bactericide and / or a flocculant to the raw water. "(16)" The ultrafiltration membrane can be washed Hollow fiber membrane,
The fresh water generator according to the above (14) or (15). (17) "The fresh water generator according to the above (16), wherein the hollow fiber membrane contains at least one compound selected from the group consisting of polyacrylonitrile, polypropylene, polyethylene, polysulfone, and polyvinyl alcohol." 18) “The membrane filtration means includes means for adding at least one additive selected from the group consisting of a reducing agent, a scale inhibitor, and a pH adjuster to water treated by the membrane filtration means. The fresh water generator according to any one of the above (13) to (17). "

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The composite semipermeable membrane of the present invention comprises a mixture of a polyfunctional acid halide and a polyfunctional acid anhydride halide, an aliphatic polyfunctional amine and an aromatic polyamine on a porous support membrane. A functional layer is provided with a separation functional layer of a crosslinked polyamide by reaction with a mixed amine with a functional amine, wherein the molar ratio of the polyfunctional acid halide to the polyfunctional acid anhydride halide is 80/2.
It is in the range of 0-10 / 90. The above, the molar ratio between the polyfunctional acid halide and the polyfunctional anhydride halide,
It is important to obtain a composite semipermeable membrane having contradictory performances of high water permeability and selective separation, and the molar ratio of both is 80.
/ 20-10 / 90, more preferably 60 / 40-30
/ 70. When the amount of the polyfunctional acid halide is more than 80 mol%, the amount of permeated water tends to decrease, and when the amount is less than 10 mol%, good selective separation tends not to be obtained.

[0013] The total of the hydrophilic group concentrations in the separation function layer analyzed by X-ray photoelectron spectroscopy (ESCA) is in the range of 0.001 to less than 0.1, and the separation function layer is Is preferably in the range of 1 to 500 nm. Here, the hydrophilic group concentration refers to the ratio of the amount of the hydrophilic group (number of moles) to the total amount of the carbon (number of moles) in the separation function layer, and is a value calculated by the following equation. The hydrophilic group is preferably at least one group selected from the group consisting of an amino group, a hydroxyl group, a carbonyl group and a sulfo group, and a carboxyl group.

[0014]

(Equation 1)

[0015] The concentration of the hydrophilic group is determined by the Journal of P
Polymer Science Vol. 26 559
-572 (1988) and Journal of the Adhesion Society of Japan, Vol.
27 No. 4 (1991) using X-ray photoelectron spectroscopy (ESCA).

The amino group concentration, hydroxyl group concentration and carboxyl group concentration can be determined by a gas phase chemical modification method using a labeling reagent. As a labeling reagent, pentafluorobenzaldehyde is used for an amino group, trifluoroacetic anhydride is used for a hydroxyl group, and trifluoroethanol is used for a carboxyl group. By changing the labeling reagent, measurement can be performed by a similar measurement method.

As an example, a method for measuring the carboxyl group concentration will be described below. The sample was subjected to gas phase chemical modification with the labeling reagent. At the same time, the reaction rate (r) of the labeling reagent and the residual rate (m) of the reaction residue were determined from the ESCA spectrum of the polyacrylic acid standard sample subjected to the gas phase chemical modification. Ask. Next, F formed by reacting the sample with the labeling reagent
The area intensity [F1s] of the 1s peak (the peak of the 1s orbital of fluorine) is determined. Further, the area intensity [C1s] of the C1s peak (peak of the 1s orbital of carbon) is obtained by elemental analysis.

The measurement conditions are shown below.

Excited X-ray: Mg K α1,2 (1253.6 eV) X-ray output: 8 kV 30 mV Photoelectron escape angle: 90 ° In data processing, the C1s peak position of neutral carbon (CHx) is adjusted to 284.6 eV.

The area intensity [F1 determined as described above
s] and [C1s] to Journalof Polyme
r Science Vol. 26 559-572
(1988), the carboxyl group concentration can be obtained by substituting into the following equation.

[0021]

(Equation 2)

R _COOH : carboxyl group concentration [F1s]: area intensity of peak of 1s orbital of fluorine kF1s: sensitivity correction value of peak of 1s orbital of fluorine r: reaction rate of labeling reagent [C1s]: 1s orbit of carbon M: Residual rate of reaction residue Further, the carbonyl group and sulfo group concentrations were measured in the Journal of the Adhesion Society of Japan, Vol. 27 No. 4 (1991), perform a wide scan and a narrow scan,
The chemical state of the element is determined from the chemical shift of the narrow scan. Next, it can be obtained by dividing the narrow scan spectrum into peaks.

When the hydrophilic group concentration is high, the water permeability increases, but the performance of removing harmful substances tends to decrease. Conversely, when the concentration of hydrophilic groups is low, the membrane becomes hydrophobic, and water permeability tends to decrease. For this reason, the sum of the hydrophilic group concentrations is 0.001 or more and less than 0.1, preferably 0.001 or more and 0.08 or less, and more preferably 0.01 or less.
It is preferably from 01 to 0.04. At the same time, the carboxyl group concentration is 0.001 or more and less than 0.03, preferably 0.001 or more and 0.025 or less. If the carboxyl group concentration exceeds 0.03, the carboxyl group end of the membrane increases and the water permeability improves, but the crosslink density decreases and the harmful substance removal performance tends to decrease. Also,
If the carboxyl group concentration is less than 0.001, unreacted terminals decrease and the crosslink density increases, so that water permeability tends to decrease.

The thickness of the separation function layer in the composite semipermeable membrane is preferably in the range of 1 to 500 nm, more preferably 1 to 100 nm, and particularly preferably 1 to 60 nm. When the film thickness is less than 1 nm, the occurrence of defects at the time of film formation is increased, the film is easily damaged during handling, and the defects are generated even when pressure is applied, so that the rejection rate is likely to be reduced. . On the other hand, if the film thickness exceeds 500 nm, the amount of permeated water decreases, and it becomes difficult to obtain a sufficient permeation amount.

The aliphatic polyfunctional amine used in the present invention is preferably a compound represented by the following formula. Among them, piperazine, 2,5-dimethylpiperazine, 2-methylpiperazine, 2,6-dimethylpiperazine,
3,5-trimethylpiperazine, 2,5-diethylpiperazine, 2,3,5-triethylpiperazine, 2-n-
Preferred are propylpiperazine, 2,5-di-n-butylpiperazine and the like, and particularly preferred is piperazine and 2,5-dimethylpiperazine.

[0026]

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R1 to R8: H, OH, COOH, SO ₃
H, NH ₂ or a hydrocarbon group An aromatic polyfunctional amine refers to an amine having two or more amino groups in one molecule, for example, metaphenylenediamine, paraphenylenediamine, 1,3,5-triamino Benzene is preferred, and N-alkylated N, N-dimethylmetaphenylenediamine, N, N-diethylmetaphenylenediamine, N, N-dimethylparaphenylenediamine, N, N-diethylparaphenylenediamine and the like are also preferred. Among them, metaphenylenediamine and 1,3,5-triaminobenzene are particularly preferred.

The molar ratio between the aliphatic polyfunctional amine and the aromatic polyfunctional amine is preferably in the range of 40/60 to 95/5, more preferably 70/30 to 90/1.
0. If the amount of the aliphatic polyfunctional amine is less than 40 mol%, the amount of permeated water tends to decrease, and if it is more than 95 mol%, good selective separation tends not to be obtained.

The polyfunctional acid halide is defined as 2 molecules per molecule.
An acid halide having at least two carbonyl halide groups, and a compound which gives a polyamide by reacting with the above amine can be used. Specifically, 1, 3,
5-cyclohexanetricarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, 1,2,2
It is preferable to use acid halides of 4-benzenetricarboxylic acid, 1,3-benzenedicarboxylic acid, and 1,4-benzenedicarboxylic acid. . In particular, from the viewpoints of economy, availability, ease of handling, and reactivity,
Trimesic acid chloride, which is an acid chloride of 5-benzenetricarboxylic acid, is preferred. Further, the above-mentioned polyfunctional acid halides can be used alone or as a mixture.

Further, the polyfunctional anhydride halide is
It has one or more acid anhydride moieties and one or more carbonyl halide groups in one molecule, and includes, for example, benzoic anhydride and phthalic anhydride carbonyl halide. The compound represented by the following formula is particularly preferable from the viewpoints of permeability and an appropriate pore diameter for removing soluble organic substances.

[0031]

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X1, X2: an aliphatic group having 1 to 6 carbon atoms, H, OH, COOH, SO ₃ H, COF, COC
1, COBr or COI or an acid anhydride group to which they are bonded X3: an aliphatic group having 1 to 6 carbon atoms, H, OH, C
OOH, SO ₃ H, COF, COCl, COBr or COI Y: F, Cl, Br or I As the porous support film, for example, a polysulfone support film reinforced by a cloth can be used. The porous support membrane is a layer having substantially no separation performance, and is used for imparting mechanical strength to a separation functional layer having substantially separation performance, and has uniform and fine pores or one side. From the other surface to the other surface, and the size of the fine hole is 100 nm on one surface.
A support membrane having the following structure is preferred. The above porous support membrane is manufactured by Millipore Corporation “Millipore Filter VSW”.
P "(trade name) and various commercially available materials such as" Ultrafilter UK10 "(trade name) manufactured by Toyo Roshi Kaisha, but usually, Office of Saline Water Research and Inc. It can be produced according to the method described in Development Progress Report No. 359 (1968), which is usually a homopolymer such as polysulfone, cellulose acetate, cellulose nitrate or polyvinyl chloride or a blend thereof. It is preferable to use polysulfone, which has high chemical, mechanical and thermal stability, for example,
A solution of the above polysulfone in dimethylformamide (DMF) is cast to a certain thickness on a densely woven polyester cloth or nonwoven fabric, and wet cast in an aqueous solution containing 0.5% by weight of sodium dodecyl sulfate and 2% by weight of DMF. By coagulating, it is possible to obtain a porous support film having most of the surface having fine pores having a diameter of several tens nm or less.

Next, a method for producing the present composite semipermeable membrane will be described.

The separation functional layer having substantially separation performance in the composite semipermeable membrane contains the above-mentioned aqueous solution containing an amine and the above-mentioned polyfunctional acid halide in the presence of the above-mentioned polyfunctional acid anhydride halide. It can be formed by using an organic solvent solution that is immiscible with water and reacting on the above-described porous support membrane.

The molar ratio between the aliphatic polyfunctional amine and the aromatic polyfunctional amine used in the present invention is 40/60 as described above.
It is preferably in the range of ９５95/5, more preferably 70/30 to 90/10. The concentration of the amine compound in the mixed amine aqueous solution is preferably in the range of 0.1 to 20% by weight, more preferably 0.5 to 20% by weight.
15% by weight. If necessary, the aqueous solution and the organic solvent solution do not interfere with the reaction between the amine compound and the polyfunctional acid halide in which the polyfunctional acid anhydride halide coexists. Compounds such as a solvent, an acid scavenger, a surfactant, and an antioxidant can be contained.

The coating of the aqueous solution of the amine on the surface of the porous support membrane may be carried out as long as the aqueous solution is uniformly and continuously coated on the surface. A method of coating, a method of immersing the porous support membrane in the aqueous solution, and the like can be used.

Next, the excessively applied aqueous amine solution is removed by a draining step. As a method of draining,
For example, a method of holding the film surface in the vertical direction and allowing the film to flow naturally can be used. After draining, the membrane surface may be dried to remove all or part of the aqueous solution.

Next, an organic solvent solution of the polyfunctional acid halide coexisting with the polyfunctional acid anhydride halide is applied, and a separation functional layer of a crosslinked polyamide is formed by reaction. The concentration of the polyfunctional acid halide is not particularly limited, but if it is too low, the formation of the separation function layer as the active layer may be insufficient, which may be a disadvantage, and if it is too high, it is disadvantageous in terms of cost. , 0.01 to 1.0% by weight
The degree is preferred. The method of contacting the polyfunctional acid halide in the presence of the polyfunctional acid anhydride halide with the aqueous amine solution phase may be carried out in the same manner as the method of coating the aqueous amine solution on the porous support membrane. The removal of the organic solvent after the reaction can be performed, for example, by the method described in JP-A-5-76740.

The organic solvent is required to be immiscible with water, dissolve the polyfunctional acid halide and not break the porous support membrane, and if it can form a crosslinked polymer by reaction. Either may be used. Representative examples include liquid hydrocarbons and halogenated hydrocarbons such as trichlorotrifluoroethane, but they are substances that do not destroy the ozone layer, are readily available, easy to handle, and safe to handle. In consideration of the above, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, heptadecane, hexadecane, etc., and a simple substance such as cyclooctane, ethylcyclohexane, 1-octene, 1-decene or a mixture thereof are preferably used.

The form of the membrane may be a hollow fiber or a flat membrane. Element type is modular type, spiral type,
A tubular type, a frame and plate type, or the like can be used.

An operating pressure of 0.1% was obtained using the composite semipermeable membrane of the present invention.
The harmful substances contained in the raw water and its precursors can be removed at 1 to 3.0 MPa. When the operating pressure is reduced, the capacity of the pump used is reduced and the power cost is reduced, but the membrane is easily clogged and the amount of permeated water is reduced. Conversely, when the operating pressure is increased, the power cost increases for the above-mentioned reason, and the amount of permeated water increases. Therefore, the operating pressure range is 0.1 to 3.0 MPa, preferably 0.1 to 3.0 MPa.
To 2.0 MPa, particularly preferably 0.1 to 1.0 MPa. If the amount of permeated water is high, clogging due to fouling on the membrane surface occurs, and if the amount is low, cost increases, so the range of permeated water is 0.5 to 5.0 m ³ / m ² · d, preferably 0.6 to 5.0 m ³ / m ² · d.
3.0 m ³ / m ² · d, especially 0.8 to 2.0 m ³ / m ²
-D is preferable in maintaining the amount of water stably. Further, in order to reduce the fresh water cost and efficiently collect the supplied water, the ratio of the permeated water amount to the raw water supply amount, that is, the recovery ratio is preferably 80% or more, preferably 85% or more, and more preferably 90% or more.

Here, the recovery rate is defined by the following formulas 1-4.
Means the value obtained by solving

1. F = B + P F × Cf = B × Cb + P × Cp 3. Removal rate = (1−Cp / Cf) × 100 Recovery rate = P / F × 100 where F: feed liquid flow rate, B: concentrate flow rate, P: permeate flow rate, Cf: solute concentration in the feed liquid, Cb: solute concentration in the concentrate (120 ppm: silica) PH = 6.5, 25 ° C.
, Cp: the solute concentration in the permeate.

The harmful substances mentioned above include trihalomethane precursors. Trihalomethane precursors produce carcinogenic trihalomethanes in chlorine disinfection at water purification plants. Examples of the trihalomethane precursor include humic acid and fulvic acid. Of these, humic acid generates a large amount of trihalomethane, and it is desirable to remove as much as possible. Further, in the case of a membrane having a low silica permeability, when a high recovery operation is performed, silica deposits on the membrane surface and blocks the membrane surface, so that there is a problem that a high amount of permeated water cannot be obtained.

Therefore, in the present invention, when the temperature is 25
C., a pH of 6.5, a silica concentration of 30 ppm, and a humic acid concentration of 2 ppm. When an aqueous solution having a humic acid concentration of 2 ppm was passed through at a pressure of 0.3 MPa for 3 hours, the silica transmittance was in the range of 55 to 90%, and humic acid was removed. The rate is 98% or more, and
A composite semipermeable membrane having a permeated water amount in the range of 0.8 to 3.0 m ³ / m ² · d is preferred. By using a composite semipermeable membrane having the above characteristics, it is possible to effectively remove a trihalomethane precursor and the like, and to permeate silica even in raw water containing 30 ppm of silica (national average). Thus, precipitation of silica can be reduced.

Here, the silica transmittance refers to a value obtained by calculating (silica concentration in the permeate / silica concentration in the feed solution) × 100 under the above conditions.
The humic acid removal rate is defined as (1− (humic acid concentration in permeate / humic acid concentration in feed)) × 1
It means a value obtained by calculating 00. The amount of permeated water refers to the amount of permeated water (m ³ / m ² · d) permeating the membrane per unit area (m ² ) per unit time (day).

By using the above-mentioned means, it has high humic acid removal property and high water permeability which cannot be achieved by conventional microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, etc., and high silica permeability. To realize a composite semipermeable membrane capable of high recovery operation. In particular, it selectively separates and removes contaminants, trace harmful substances, and their precursors contained in raw water from clean water purification plants, transmits silica, and produces drinking water such as drinking water under high recovery operation. Can be used.

Next, a desalination apparatus using the composite semipermeable membrane of the present invention will be described.

In the fresh water generator 50 shown in FIG. 1, raw water is filtered through a raw water channel 1 by a sand filtration device (coarse filtration device) 2 having an additive adding means 20 and then into a raw water tank 3.
Is stored in Next, after being supplied to the ultrafiltration means 5 by the pressure pump 4 and filtered, the pressure is further supplied to the membrane filtration device (membrane filtration means) 6 provided with the additive addition means 30 by the pressure pump 41. The concentrated water by the membrane filtration means 6 is
Further, the water is supplied to the reverse osmosis filtration means 9 through the concentrated water channel 7 by the pressurizing pump 42 to perform filtration. The concentrated water from the reverse osmosis filtration unit 9 is discharged through the concentrated water passage 8, while the permeated water is taken out from the permeation passages 10 and 11 in the same manner as the permeated water from the membrane filtration unit 6.

In the fresh water generator of the present invention, the coarse filtration means has a function of removing large foreign substances such as wood chips and leaves from raw water such as river water, well water, ground water, lake water, brackish water, and seawater. A strainer or a sand filtration device using sand and anthracite as a filter medium can be used. Further, it is preferable that the coarse filtration means includes a means for adding a bactericide and / or a flocculant, if necessary. As a disinfectant, for example, sodium hypochlorite which is an oxidizing agent can be used. In addition, turbid or colloidal substances contained in raw water can be flocculated using polyaluminum chloride or ferric chloride as a flocculant, and can be filtered by coarse filtration means.

Next, if necessary, the coarsely filtered water obtained by the coarse filtration means is further filtered by an ultrafiltration means using an ultrafiltration membrane to maintain the performance of the membrane filtration means described later for a long time. It can be preferable. As the ultrafiltration means, for example, a hollow fiber membrane module in which a plurality of hollow fiber membranes are bundled can be used. It is more preferable that the hollow fiber membrane can be subjected to reverse flow washing of filtered water, air flushing with air or scrubbing washing. The pore size of the hollow fiber membrane is preferably 10 μm or less, more preferably 1 μm or less. In order to further remove fine solids, it is preferable to use one having a pore diameter of 0.1 μm. Further, the hollow fiber membrane preferably contains at least one selected from the group consisting of polyacrylonitrile, polypropylene, polyethylene, polysulfone, and polyvinyl alcohol, and in particular, an acrylonitrile copolymer obtained by copolymerizing acrylonitrile and a vinyl compound. It is preferable to use.

Next, the filtered water obtained by the above-mentioned filtration means is filtered by the above-mentioned membrane filtration means using the composite semipermeable membrane. The composite semipermeable membrane of the present invention has a high molecular weight-removing performance of polyvalent ions such as medium to high molecular weight molecules and heavy metal ions, and a low molecular weight such as monovalent ions and silica. Since molecules are easily transmitted, it is possible to efficiently remove a trihalomethane precursor and the like and to suppress generation of harmful substances.

It is preferable that the membrane filtration means is provided with, if necessary, means for adding at least one additive selected from the group consisting of a reducing agent, a scale inhibitor and a pH adjuster.

As the reducing agent, for example, sodium bisulfite can be used, and sodium hypochlorite used as a germicide can be neutralized to prevent deterioration of the film.

The scale inhibitor may be any agent which forms a complex with a scale component such as a polyvalent metal ion to prevent the generation of scale, and an ionic polymer or the like can be used. Specifically, it is preferable to use polyacrylic acid or polyacrylamide, and it is preferable to use polyphosphate or the like as an inorganic material. The addition concentration of the scale inhibitor is preferably in the range of 0.01 to 1,000 ppm, and more preferably in the range of 0.1 to 100 ppm, in consideration of the cost and the time required for the addition. If the addition concentration is less than 0.01,
Scale easily occurs. When the amount exceeds 1,000 ppm, the scale inhibitor itself is adsorbed on the membrane surface, and the amount of fresh water is easily reduced.

Examples of the pH adjusting agent include alkalis such as sodium hydroxide and sodium carbonate, hydrochloric acid, sulfuric acid, and the like.
Acids such as oxalic acid and citric acid can be used.

Next, when the elimination of monovalent ions and low molecular weight molecules is not sufficient, the water filtered by the above-mentioned membrane filtration means is used.
Further, it is preferable to perform filtration using reverse osmosis filtration means for performing filtration using a reverse osmosis membrane. As the reverse osmosis membrane, a hollow fiber membrane or a flat membrane using polyamide, polyester, polyimide, or cellulose acetate polymer can be used. Among them,
A composite film using polyamide is preferred. It is particularly preferable to use a reverse osmosis membrane having a permeated water amount in the range of 0.8 to 3.0 m ³ / m ² · d and having a sodium chloride rejection of 95% or more. Here, the amount of water permeated through the reverse osmosis membrane refers to an aqueous solution having a temperature of 25 ° C., a pH of 6.5, and a sodium chloride concentration of 1,500 ppm at a pressure of 1.5 MPa
The amount of permeated water when permeated in a is referred to, and the sodium chloride exclusion ratio is calculated by ((concentration of sodium chloride in feed solution-concentration of sodium chloride in permeate solution) / (concentration of sodium chloride in feed solution)) × 100. The value to be used. This sodium chloride concentration can be determined, for example, by measuring electric conductivity.

[0058]

EXAMPLES The fiber-reinforced polysulfone support membranes (porous support membranes) used in the examples and comparative examples were produced by the following method.

A taffeta made of polyester fiber having a length of 30 cm and a width of 20 cm (a multifilament yarn of 150 denier for both the warp and the weft, the weaving density of 90 / inch, the width of 67 / inch, the thickness of 160 μm) is applied to a glass plate. A 15% by weight solution of polysulfone (Udel-P3500 manufactured by Union Carbide) in dimethylformamide (DMF) was cast at a thickness of 200 μm at room temperature (20 ° C.), and immediately poured into pure water. Soak 5
After standing for a few minutes, a fiber-reinforced polysulfone support membrane (hereinafter referred to as FR-PS support membrane) was obtained.

The amount of fresh water of the thus obtained FR-PS support film (thickness: 210 to 215 μm) was adjusted to a pressure of 0.1 M
It was 1.7 m ³ / m ² · d measured at Pa and a temperature of 25 ° C. In addition, a test was conducted under the same conditions as above using 2 ppm humic acid adjusted to pH 6.5 as raw water, and as a result, the humic acid removal rate was 60%. Further, Na ₂ SiO ₃
An aqueous solution in which 9H ₂ O was dissolved as equivalent to 30 ppm as SiO ₂ was used as raw water and tested under the same conditions as for humic acid. As a result, the transmittance of silica was 99.9%. (Example 1) Piperazine was added to an aqueous solution containing m-phenylenediamine so that the molar ratio of m-phenylenediamine / piperazine was 15/85 at a total weight of 3% by weight of the entire amine, and the FR-PS support film was added thereto. Dipped for 1 minute. The support film is slowly pulled up in the vertical direction to remove excess aqueous solution from the surface of the support film.
A solution in which trimesic acid chloride / trimellitic anhydride chloride is added to a decane solution containing 06% by weight of trimellitic anhydride chloride in a molar ratio of 50/50 is applied so that the surface is completely wetted. Let stand for 1 minute. Next, after the film was removed vertically and the excess solution was drained and removed, air having a wind speed of 8 m / s and a temperature of 30 ° C. was blown on the film surface for 1 minute to evaporate the solvent remaining on the film surface. . This membrane was immersed in a 1% by weight aqueous solution of sodium carbonate for 5 minutes, and then sufficiently washed with water to produce a composite semipermeable membrane.

The composite semipermeable membrane obtained in this manner is adjusted to pH
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 3 MPa and 25 ° C., the amount of fresh water was 1.45 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was conducted under the same conditions as for humic acid using an aqueous solution in which O was dissolved as SiO _{2 so} as to be equivalent to 30 ppm, and as a result, the transmittance of silica was 91.5%. At this time, the calculated recovery was 97.2%.

The carboxyl group concentration was found to be 0.019 by X-ray photoelectron spectroscopy (ESCA), and the total sum of the hydrophilic group concentrations was found to be 0.027. (Example 2) Piperazine was added to an aqueous solution containing m-phenylenediamine so that the ratio of m-phenylenediamine / piperazine to m / phenylenediamine / piperazine was 10/90 in a molar ratio of 3% by weight, and 0.06% by weight of trimesic acid chloride was added. A composite semipermeable membrane was produced in the same manner as in Example 1 except that trimellitic anhydride chloride / trimellitic anhydride chloride was added to the contained decane solution in a molar ratio of 45/55. .

The composite semipermeable membrane obtained in this manner is adjusted to pH
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 3 MPa and 25 ° C., the amount of fresh water was 1.65 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which O was dissolved as equivalent to 30 ppm of SiO ₂ as raw water. As a result, the transmittance of silica was 84.2%.

At this time, the recovery rate was calculated to be 95.0%
Met.

The carboxyl group concentration determined by X-ray photoelectron spectroscopy (ESCA) was 0.019. (Example 3) Piperazine was added to an aqueous solution containing m-phenylenediamine so that the molar ratio of m-phenylenediamine / piperazine was 20/80 at a total of 3% by weight of amine, and 0.06% by weight of trimesic acid chloride was added. A composite semipermeable membrane was produced in the same manner as in Example 1 except that trimellitic anhydride chloride was added to the contained decane solution in a molar ratio of trimesic acid chloride / trimellitic anhydride chloride = 40/60. .

The composite semipermeable membrane thus obtained was subjected to a pH adjustment.
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 3 MPa and 25 ° C., the amount of fresh water was 1.52 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid, using an aqueous solution in which O was dissolved as equivalent to 30 ppm of SiO ₂ as raw water. As a result, the transmittance of silica was 73.9%.

At this time, the recovery rate was calculated to be 92.0%
Met. The carboxyl group concentration determined by X-ray photoelectron spectroscopy (ESCA) was 0.017. (Example 4) Piperazine was added to an aqueous solution containing m-phenylenediamine so that the ratio of m-phenylenediamine / piperazine was 20/80 at a total weight of 3% by weight of amine, and 0.06% by weight of trimesic acid chloride was added. A composite semipermeable membrane was produced in the same manner as in Example 1 except that trimellitic anhydride chloride / trimellitic anhydride chloride = 70/30 molar ratio was added to the contained decane solution. .

The composite semipermeable membrane obtained in this manner is adjusted to pH
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 5 MPa and 25 ° C., the amount of fresh water was 0.85 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which O was dissolved so as to be equivalent to 30 ppm as SiO ₂ , and as a result, the transmittance of silica was 67.1%.

At this time, the recovery rate was calculated to be 90.1%
Met.

The total sum of the hydrophilic group concentrations obtained by X-ray photoelectron spectroscopy (ESCA) was 0.022. Example 5 Piperazine was added to an aqueous solution containing m-phenylenediamine so that the total amine content was 3% by weight and the molar ratio of m-phenylenediamine / piperazine was 15/85, and 0.06% by weight of trimesic acid chloride was added. A composite semipermeable membrane was produced in the same manner as in Example 1 except that trimellitic anhydride chloride / trimellitic anhydride chloride = 15/85 molar ratio was added to the contained decane solution. .

The composite semipermeable membrane thus obtained was subjected to pH adjustment.
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 5 MPa and 25 ° C., the amount of fresh water was 1.70 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which O was dissolved as SiO _{2 so} as to be equivalent to 30 ppm, and as a result, the transmittance of silica was 88.9%.

At this time, the recovery rate was calculated to be 96.4%
Met. The carboxyl group concentration determined by X-ray photoelectron spectroscopy (ESCA) was 0.021. (Example 6) The composite semipermeable membrane used in Example 1 (film area: 7 m
^{Using 2} ) as a membrane filtration means, a fresh water generator as shown in FIG. 1 was produced. A sand filtration device was used as the coarse filtration means, and a filtration module using a hollow fiber membrane was used as the ultrafiltration means. This hollow fiber membrane filtration module has an outer diameter of 680 μm,
A 1,000 mm long hollow fiber membrane bundle consisting of 7,400 polyacrylonitrile porous hollow fiber membranes having an inner diameter of 400 μm and an average pore diameter of 0.01 μm is inserted into a housing of a rigid PVC pipe and both ends thereof Adhesively fixed,
It has a shape in which the end is cut to open the inside of the hollow fiber membrane at both ends.

Using this apparatus, raw water containing 1,500 ppm of sodium chloride and 2 ppm of humic acid was treated. First, in a sand filtration device, polyaluminum chloride as a flocculant is added to raw water so as to have a concentration of 5 mg / l, and the FI value (fouling index: degree of clogging by suspended substances contained in water) is reduced to 4 or less. So that
Fine foreign substances and colloidal substances were captured as flocculated flocs and filtered.

Next, sodium hydroxide was added to the treated water so that the pH was 6.5, and the temperature was 25 ° C. and the pressure was 0.1 MPa in the hollow fiber membrane module (ultrafiltration means).
Filtration was performed under the condition of a, and the treated water was supplied to a membrane filtration means.

In the membrane filtration means, a pressure of 0.3 MPa
To obtain permeated water and concentrate water at 1.5 MPa
And supplied to reverse osmosis filtration means using a reverse osmosis membrane to obtain permeated water.

The obtained permeated water had a sodium chloride concentration of 1
95 ppm, 87% sodium chloride rejection, humin
The acid exclusion was 99.7%. The amount of fresh water is 6.
8m ^Three/ D (0.97m^Three/ M^Two・ D) and 30 days
No decrease in the amount of fresh water was observed after a while. (Example 7) Except that no reverse osmosis filtration means was used,
Raw water was filtered in the same manner as in Example 6.

The concentration of sodium chloride in the permeated water obtained by the membrane filtration means was 225 ppm, the rejection of sodium chloride was 85%, and the rejection of humic acid was 99.5%. Further, desalination amount ^{6.9m 3 /d(0.99m 3 / m 2 ·} d)
No decrease in the amount of fresh water was observed even after 35 days. (Example 8) The same fresh water generator as in Example 6 was used except that the ultrafiltration means and the reverse osmosis filtration means were not used.
Raw water containing ppm sodium chloride and 2 ppm humic acid was treated. In the same manner as in Example 5, except that ferric chloride was added as a coagulant to the raw water so as to be 3.5 mg / l in the sand filtration device so that the FI value was 4 or less. Processing was performed.

The sodium chloride concentration of the obtained permeated water was 8
It was 0 ppm, the rejection of sodium chloride was 84%, and the rejection of humic acid was 99.7%. Further, desalination amount is ^{6.8m 3 /d(0.97m 3 / m 2 ·} d), 30
No decrease in the amount of fresh water was observed after a lapse of days. (Comparative Example 1) The FR-PS support membrane was immersed in an aqueous solution containing 3% by weight of m-phenylenediamine for 1 minute. The support film was slowly pulled up in the vertical direction to remove excess aqueous solution from the surface of the support film.
A decane solution containing weight% was applied so that the surface was completely wetted, and was allowed to stand for 1 minute. Next, after the film was removed vertically and the excess solution was drained and removed, air having a wind speed of 8 m / s and a temperature of 30 ° C. was blown on the film surface for 1 minute to evaporate the solvent remaining on the film surface. . This membrane was immersed in a 1% by weight aqueous solution of sodium carbonate for 5 minutes, and then sufficiently washed with water to produce a composite semipermeable membrane.

The composite semipermeable membrane obtained in this manner is adjusted to pH
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 3 MPa and 25 ° C., the amount of fresh water was 0.33 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which O was dissolved as SiO _{2 so} as to be equivalent to 30 ppm, and as a result, the transmittance of silica was 0.5%.
At this time, the calculated recovery was 75.1%.

The carboxyl group concentration determined by X-ray photoelectron spectroscopy (ESCA) was 0.016. (Comparative Example 2) Piperazine was added to an aqueous solution containing m-phenylenediamine so that the molar ratio of m-phenylenediamine / piperazine was 15/85 at a total weight of 3% by weight of the entire amine, and the FR-PS support membrane was added thereto. Dipped for 1 minute. The support film is slowly pulled up in the vertical direction to remove excess aqueous solution from the surface of the support film.
A solution obtained by adding trimellitic anhydride chloride to a decane solution containing 06% by weight of trimesic acid chloride / trimellitic anhydride chloride = 85/15 molar ratio was applied so that the surface was completely wetted. Let stand for 1 minute. Next, after the film was removed vertically and the excess solution was drained and removed, air having a wind speed of 8 m / s and a temperature of 30 ° C. was blown on the film surface for 1 minute to evaporate the solvent remaining on the film surface. . This membrane was immersed in a 1% by weight aqueous solution of sodium carbonate for 5 minutes, and then sufficiently washed with water to produce a composite semipermeable membrane.

The composite semipermeable membrane obtained in this way is
2. 2 ppm humic acid adjusted to 6.5 was used as raw water;
As a result of a reverse osmosis test under the conditions of 3 MPa and 25 ° C., the amount of fresh water was 15.3 m ³ / m ² · d, and the removal rate of humic acid was 9
It was 9.5% or more. In addition, Na ₂ SiO ₃ · 9H ₂
A reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which O was dissolved as SiO _{2 so} as to be equivalent to 30 ppm, and as a result, the transmittance of silica was 15.4%.

At this time, the recovery rate was calculated to be 78.0%
Met.

The carboxyl group concentration determined by X-ray photoelectron spectroscopy (ESCA) was 0.017. (Comparative Example 3) Trimetic acid chloride was added to a decane solution containing 0.06% by weight of trimesic acid chloride except that trimellitic anhydride chloride was added at a molar ratio of trimesic acid chloride / trimellitic anhydride chloride = 5/95. A composite semipermeable membrane was produced in the same manner as in Comparative Example 2.

The composite semipermeable membrane thus obtained was subjected to pH adjustment.
2 ppm humic acid adjusted to 6.5 was used as raw water.
As a result of a reverse osmosis test under the conditions of 08 MPa and 25 ° C.,
The amount of fresh water is 0.45 m ³ / m ² · d, and the removal rate of humic acid is 9
0.5%. Further, a reverse osmosis test was carried out under the same conditions as for humic acid using an aqueous solution in which Na ₂ SiO ₃ .9H ₂ O was dissolved as equivalent to 30 ppm as SiO _2. As a result, the transmittance of silica was 60.5%. Met. At this time, the calculated recovery was 88.4%.

The total sum of the hydrophilic group concentrations obtained by X-ray photoelectron spectroscopy (ESCA) was 0.026. (Comparative Example 4) A fresh water generator similar to that of Example 8 was used except that a reverse osmosis filtration unit was used instead of the membrane filtration unit.
Raw water at pH 6.5 containing 0 ppm sodium chloride and 30 ppm silica was treated. The reverse osmosis filtration means was operated at a temperature of 25 ° C. and a pressure of 1.5 MPa.

The sodium chloride concentration of the obtained permeated water was 7.5 ppm, and the rejection of sodium chloride was 99.9 ppm.
5% and the rejection of silica was 98.5%. Further, desalination amount ^{6.8m 3 /d(0.97m 3 / m 2 ·} d) a had been, but after 30 days 5.8m ³ /d(0.83m ³ /
m ² · d), and the reduction rate reached 15%. (Comparative Example 5) A fresh water generator similar to that of Example 7 was used except that a reverse osmosis filtration means was used instead of the membrane filtration means.
Raw water at pH 6.5 containing 0 ppm sodium chloride and 30 ppm silica was treated. The reverse osmosis filtration means was operated at a temperature of 25 ° C. and a pressure of 1.5 MPa.

The sodium chloride concentration of the obtained permeated water was 6.0 ppm, and the rejection of sodium chloride was 99.9 ppm.
6% and the rejection of silica was 99.1%. In addition, the amount of fresh water was 7.0 m ³ / d (1.0 m ³ / m ² · d), but after 30 days, 6.2 m ³ / d (0.89 m ³ / m).
² · d), and the decrease rate reached 11%.

[0088]

[Table 1]

The abbreviations in Table 1 are as follows. m-PDA: metaphenylenediamine PIP: piperazine TMC: trimesic acid chloride TMAC: trimellitic anhydride chloride Thus, as shown in each example, the molar ratio between the polyfunctional acid halide and the acid anhydride halide is determined as follows. It can be seen that by specifying, toxic substances typified by humic acid can be removed at a high level, and the recovery rate also increases.

[0090]

According to the present invention, a composite semipermeable membrane having high water permeability can be obtained. By using this, contaminants and trace harmful substances contained in raw water can be selectively separated and removed. Recovery operation becomes possible. In particular, it is effective for pretreatment of drinking water such as drinking water.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart of a fresh water generator according to one embodiment of the present invention.

[Explanation of symbols]

 1: Raw water channel 2: Sand filtration device (coarse filtration means) 3: Raw water tank 4: Pressurized pump 5: Ultrafiltration means 6: Membrane filtration means 7: Concentrated water path 8: Concentrated water path 9: Reverse osmosis filtration means 10: Permeate channel 11: Permeate channel 20: Additive adding means 30: Additive adding means 41: Pressurizing pump 42: Pressurizing pump 50: Fresh water generator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme coat ゛ (Reference) C02F 1/44 C02F 1/44 H ZAB ZABK

Claims (18)

[Claims] 1. Crosslinking on a porous support membrane by reaction of a mixture of a polyfunctional acid halide and a polyfunctional acid anhydride halide with a mixed amine of an aliphatic polyfunctional amine and an aromatic polyfunctional amine. A composite semipermeable membrane comprising a polyamide separation function layer, wherein the molar ratio of the polyfunctional acid halide to the polyfunctional acid anhydride halide is in the range of 80/20 to 10/90. . 2. The method according to claim 1, wherein the total of the concentration of the hydrophilic groups in the separation function layer is 0.00, analyzed by X-ray photoelectron spectroscopy (ESCA).
The composite semipermeable membrane according to claim 1, wherein the thickness is in the range of 1 to less than 0.1, and the thickness of the separation function layer is in the range of 1 to 500 nm. 3. The at least one hydrophilic group selected from the group consisting of an amino group, a hydroxyl group, a carbonyl group and a sulfo group.
The composite semipermeable membrane according to claim 1, wherein the composite semipermeable membrane comprises one group and a carboxyl group. 4. The composite semipermeable membrane according to claim 1, wherein the aliphatic polyfunctional amine is a compound represented by the following formula. Embedded image R1 to R8: H, OH, COOH, SO ₃ H, NH ₂ or a hydrocarbon group 5. The aromatic polyfunctional amine is at least one compound selected from the group consisting of metaphenylenediamine, paraphenylenediamine, 1,3,5-triaminobenzene and N-alkylated products thereof. Item 5. The composite semipermeable membrane according to any one of Items 1 to 4. 6. The molar ratio between the aliphatic polyfunctional amine and the aromatic polyfunctional amine is in the range of 40/60 to 95/5,
The composite semipermeable membrane according to claim 1. 7. The method according to claim 1, wherein the polyfunctional acid halide is a polyfunctional acid chloride, and the polyfunctional acid anhydride halide is a compound represented by the following formula. Composite semipermeable membrane. Embedded image X1, X2: an aliphatic group having 1 to 6 carbon atoms, H, O
H, COOH, SO ₃ H, COF, COCl, COBr
Or COI or an acid anhydride group to which they are bonded X3: an aliphatic group having 1 to 6 carbon atoms, H, OH, C
OOH, SO ₃ H, COF, COCl, COBr or COI Y: F, Cl, Br or I 8. The composite semipermeable membrane according to claim 1, wherein the porous support membrane contains polysulfone. 9. An aqueous solution having a temperature of 25 ° C., a pH of 6.5, a silica concentration of 30 ppm and a humic acid concentration of 2 ppm having a silica permeability of 55 to 90% when passed through a pressure of 0.3 MPa for 3 hours. And the humic acid removal rate is 9
8% or more and the amount of permeated water is 0.8 to 3.0 m ³
The composite semipermeable membrane according to any one of claims 1 to 8, which is in the range of / m ² · d. 10. A fresh water producing method, comprising removing harmful substances contained in water and precursors thereof using the composite semipermeable membrane according to claim 1. 11. The fresh water producing method according to claim 10, wherein the harmful substance is trihalomethane. 12. The fresh water producing method according to claim 10, wherein a water recovery rate is 80% or more. 13. A desalination comprising: a coarse filtration means for coarsely filtering raw water; and a membrane filtration means for filtering by using the composite semipermeable membrane according to any one of claims 1 to 9. apparatus. 14. An ultrafiltration means using an ultrafiltration membrane is provided between the coarse filtration means and the membrane filtration means.
A desalination apparatus according to claim 1. 15. The fresh water generator according to claim 13, wherein the coarse filtration means includes means for adding a bactericide and / or a flocculant to the raw water. 16. The fresh water generator according to claim 14, wherein the ultrafiltration membrane is a washable hollow fiber membrane. 17. The method according to claim 17, wherein the hollow fiber membrane is at least one selected from the group consisting of polyacrylonitrile, polypropylene, polyethylene, polysulfone and polyvinyl alcohol.
17. The fresh water generator of claim 16, comprising a species compound. 18. The membrane filtration means includes means for adding at least one additive selected from the group consisting of a reducing agent, a scale inhibitor and a pH adjuster to water treated by the membrane filtration means. The fresh water generator according to any one of claims 13 to 17.