KR101273334B1 - Chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane and a preparation method thereof, and more particularly, to a porous support; A polyamide active layer formed on the porous support; And it relates to a chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane comprising a hydrophilic polymer layer formed on the active layer and a method for producing the same.
According to the present invention, by forming a hydrophilic polymer layer on the surface of the polyamide active layer, not only physically block the chlorine attack, but also modify the surface properties to improve the chlorine resistance and fouling resistance at the same time while retaining the properties of salt rejection and permeate flow rate You can.

Description

Chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane and manufacturing method

The present invention relates to a polyamide reverse osmosis composite membrane excellent in chlorine resistance and fouling resistance and a method for producing the same.

Seawater desalination is a costly process compared to reservoirs such as dams to produce water resources.

Numerous studies are under way to improve the production efficiency of fresh water by developing process systems, developing facility process technology capable of recovering energy, optimizing operation conditions, developing high performance membranes, and developing pollution resistance / ultra high pressure materials and equipment.

At present, 20 million m ³ / day of fresh water is produced by desalination, and evaporation, reverse osmosis, and electrodialysis are widely applied to this desalination process.

While the improvement of freshwater production efficiency by the evaporation method has reached its limit, freshwater production using reverse osmosis membranes has been reported to be innovatively improved such as reuse of concentrated water.

Semi-saline desalination or desalination of seawater using a reverse osmosis membrane consists of pressurizing an aqueous solution containing salt or ions and passing the reverse osmosis membrane, where salt or ions in the aqueous solution cannot be passed through the membrane and only water is filtered. It is purified by fresh water through the membrane.

The reverse osmosis is a technology that has been used for the past 30 years and is highly matured. Recently, technologies that can obtain high recoveries even at low pressures are being developed one after another.

Cellulose acetates and derivatives that were initially developed as materials for reverse osmosis membranes have been used, but there are many problems in separation of chemicals, heat resistance, contamination resistance, and the like. Therefore, in recent years, the use of thin film composite (TFC) membranes having a polyamide thin film as an active layer, which has better mechanical strength and separation selectivity than cellulose acetate materials, has been increasing.

Polyamide-based reverse osmosis membrane is a polyamide active layer is formed, but this layer is made of cross-linking has a disadvantage in weak reaction to the radical reaction, and is easily damaged by chlorine has a disadvantage of short life.

In the actual water treatment process, chlorine-containing substances such as NaOCl, Ca (OCl) ₂ , Cl ₂ and NH ₂ Cl are included in raw water for sterilization purposes. Thus, continuous chlorine contact degrades the polyamide membrane's excellent separation performance and eventually shortens the membrane's lifetime.

In addition, when using a polyamide reverse osmosis composite membrane, suspended solids or dissolved substances are adsorbed or adhered to the membrane surface due to hydrophobic bonding and electrostatic attraction. Due to the deterioration of performance, it is difficult to frequently calibrate the pressure in order to obtain a certain amount of permeate, and in serious cases, there is a problem that requires frequent washing.

In order to solve these drawbacks, studies have been actively conducted such as introducing functional groups having excellent resistance to chlorine to polyamide bonds, but there have been significant limitations in the preparation of reverse osmosis membrane membranes having improved chlorine resistance and fouling resistance.

Korean Patent Publication No. 10-2011-0056672

In order to solve the above problems, it is an object of the present invention to provide a polyamide reverse osmosis composite membrane and a method for producing the same, which satisfies chlorine resistance and fouling resistance at the same time while retaining the properties of salt excretion and permeation flux.

To this end,

A porous support;

A polyamide active layer formed on the porous support; And

Anionic or cationic hydrophilic polymer layer formed on the active layer

It provides a chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane comprising a.

Also,

1) a polyamide active layer is formed by interfacial polymerization of a porous support and a polyfunctional amine and an amine reactive compound on the porous support,

2) forming a hydrophilic polymer layer on the polyamide active layer using a coating solution containing a hydrophilic polymer, an ionic strength adjusting salt and water

Provided are a method for producing a chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane.

According to the present invention, by modifying the surface of the polyamide reverse osmosis composite membrane with a hydrophilic polymer, chlorine attack to the amide bond of the polyamide active layer is physically blocked, thereby greatly improving chlorine resistance.

In addition, pollution resistance is improved through hydrophilic modification of the surface, thereby preventing a decrease in permeability due to membrane contamination. Such a polyamide composite membrane of the present invention can be extended due to the excellent chlorine resistance and fouling resistance properties to reduce the management cost, it can be widely applied to the reverse osmosis membrane process of various fields.

1 is a perspective view showing a composite membrane according to an embodiment of the present invention.
Figure 2 is a graph showing the results of measuring the contact angle (Contact angle) in order to observe the film surface change before and after the polymer coating.
3 is a graph showing the results of measuring the chlorine resistance of the TFC polyamide film before coating treatment.
4 to 6 is a 100 ppm aqueous solution of NaCl in a composite film prepared by coating a 1000 ppm aqueous solution of polyethyleneimine (Ion intensity control salt: Mg (NO ₃ ) ₂ · 6H ₂ O) for 10 seconds, 30 seconds, 60 seconds, respectively. This is the result of the permeation test performed.
7 to 9 are permeated using a 100 ppm NaCl aqueous solution of a composite membrane prepared by coating a 1000 ppm aqueous solution of polyethyleneimine I (a salt for controlling ion strength: NaCl, an ion strength of 0.1) for 10 seconds, 30 seconds, and 60 seconds, respectively. The result of the test.
10 and 11 are the results of the permeation test using a 100 ppm NaCl aqueous solution of a composite membrane prepared by coating the polyethyleneimine 1,000 ppm aqueous solution (ionic strength control salt: NaCl ion strength: 0.2) for 10 seconds, 30 seconds respectively. .
12 is a result of performing a permeation test using a 100 ppm NaCl aqueous solution of a composite membrane prepared by coating the polyethyleneimine 2,000 ppm aqueous solution (ionic strength control salt: NaCl ion strength: 0.1) for 10 seconds.
13 to 15 are The result of permeation test using 100 ppm NaCl aqueous solution for a composite membrane prepared by coating polyvinyl sulfonic acid 1,000 ppm aqueous solution (ionic strength control salt: NaCl ion strength: 0.1) for 10 seconds, 30 seconds, and 60 seconds, respectively. .
FIG. 16 shows the results of permeation testing of a composite membrane prepared by coating a 1000 ppm aqueous polyvinylsulfonic acid solution for 10 seconds using an aqueous 100 ppm NaCl solution.
FIG. 17 and FIG. 18 show a composite membrane using 2,000 ppm aqueous polyvinylsulfonic acid prepared using Mg (NO ₃ ) _{2 ·} 6H ₂ O and NaCl as salts for ion control, and using 100 ppm NaCl aqueous solution. This is the result of the permeation test.
19 is a permeation test of a composite membrane prepared by coating a polyvinylsulfonic acid 2,000 ppm aqueous solution (ion intensity control salt: Mg (NO ₃ ) _{2 ·} 6H ₂ O ion strength: 0.1) for 60 seconds using a 100 ppm NaCl aqueous solution. This is the result.
20 is a permeation test of a composite membrane prepared by coating polyvinylsulfonic acid 3,000 ppm (a salt for controlling ion strength: Mg (NO ₃ ) _{2 ·} 6H ₂ O ion strength: 0.1) for 10 seconds using an aqueous 100 ppm NaCl solution. It is the result of implementation.
FIG. 21 shows the results of conducting chlorine resistance experiments after preparing a membrane through crosslinking with glutaraldehyde after coating with 2,000 ppm aqueous polyvinyl alcohol.
Figure 22 shows the resistance time to serum serum albumin contamination of the composite membrane prepared by coating with polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.
Figure 23 shows the resistance time to sodium alginate salt contamination of the composite membrane prepared by coating with a polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.
Figure 24 shows the resistance time to humic acid contamination of the composite membrane prepared by coating with a polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.
FIG. 25 is a photograph taken by SEM to evaluate fouling resistance of Bovine Serum Albumin contamination of a composite membrane prepared by coating with an aqueous 2,000 ppm polyvinylamine solution. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

1 is a cross-sectional view showing a composite film according to an embodiment of the present invention.

Referring to the drawings, the composite membrane 10 according to an embodiment of the present invention can purify the purified water as raw water, such as tap water, natural water, etc. through a filter system, and discharge the purified water to the outside. It can be applied to water treatment apparatus.

The composite membrane 10 forms a hydrophilic polymer layer on the surface of the polyamide active layer, not only physically blocks chlorine attack, but also modifies the surface properties to maintain chlorine excretion and permeate flow characteristics, while simultaneously providing excellent chlorine and fouling resistance. Can be improved.

To this end, the composite membrane 10 according to the present invention is a porous support (2); A polyamide active layer 4 formed on the porous support; And a hydrophilic polymer layer 6 formed on the active layer.

Referring to FIG. 1, the composite membrane 10 has a structure in which a polyamide active layer 4 on a porous support 2 and a hydrophilic polymer layer 6 are stacked on the polyamide active layer 4.

The porous support 2 can be used without limitation as long as it can serve as a support for forming a thin film while having a microporous water permeable, the pore size is 1 to 500 nanometers, the thickness is 25 to 125 ㎛ Is preferably. For example, polysulfone, polyisulfone, polyimide, polyethylene, polypropylene, polyamide, polyimide, polyacrylonitrile, polymethyl methacrylate, or polyvinylidene fluoride may be used. The shape of the porous support 2 is also not particularly limited.

The polyamide active layer 2 is formed by interfacial polymerization of a polyfunctional amine and an amine reactive compound on the porous support 2.

This polyamide active layer 2 is a thin film layer showing the separation performance of the reverse osmosis composite membrane.

In the present invention, the surface of the polyamide active layer 2 is modified with a hydrophilic polymer to improve chlorine resistance and fouling resistance at the same time.

The hydrophilic polymer layer 6 includes an anionic or cationic hydrophilic polymer. Here, the anionic hydrophilic polymer refers to a negatively charged polymer having hydrophilicity, and a polymer containing a carboxylic acid group and a sulfonic acid group is preferable. For example, polyvinyl sulfonic acid (PVSA), polyacrylic acid (PAA), polystyrene sulfonic acid (PSSA), polyacrylic acid-co-maleic acid (PAM), polystyrene sulfonic acid-co-maleic acid (PSSA-MA), and polyacrylamide-co-acrylic acid (PAAM).

The cationic hydrophilic polymer is a positively charged polymer having a hydrophilic property, and preferably a polymer containing an amino group, an imino group or an amido group. Specifically, polyvinylamine, polyallylamine, and polyethyleneimine are possible.

More preferably, the hydrophilic polymer layer 6 is formed of polyvinylsulfonic acid, polyethyleneimine, polystyrenesulfonic acid, or polyvinylamine.

In the case of hydrophilic polymers, there is a disadvantage in that they are gradually washed away from the membrane by contact with water over time, and this tendency is further increased in the case of contact with hot water. However, in the case of the present invention, since the anionic or cationic hydrophilic polymer layer and the polyamide active layer are electrically coupled, durability of the composite membrane may be enhanced.

As described above, the composite membrane according to the present invention has a hydrophilic polymer layer is formed on the polyamide reverse osmosis composite membrane to modify the surface properties, prevent the reaction with chlorine, not only greatly improve the chlorine resistance but also prevent membrane fouling. The permeation | transmission performance fall can be prevented. Accordingly, the service life of the polyamide composite membrane can be extended, thereby reducing the management cost.

In the composite membrane of the present invention,

1) a polyamide active layer is formed by interfacial polymerization of a porous support and a polyfunctional amine and an amine reactive compound on the porous support,

2) is prepared by forming a hydrophilic polymer layer on the polyamide active layer using a coating solution containing a hydrophilic polymer, ionic strength control salt and water.

First, a polyamide active layer is formed by interfacial polymerization of a polyfunctional amine and an amine reactive compound on a porous support.

Since the polyamide active layer formation method through such interfacial polymerization is well known in the art, a detailed description thereof will be omitted.

In this case, the polyfunctional amine may be 1,4-phenylenediamine, 1,3-phenylenediamine, 2,5-diaminotoluene, N, N'-diphenylethylene diamine, 4-methoxyphenylenediamine and their One selected from the group consisting of mixtures may be used.

The amine reactive compound may be a polyfunctional acyl halide, a polyfunctional sulfonyl halide or a polyfunctional isocyanate, preferably 1 selected from the group consisting of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, and mixtures thereof. Species polyfunctional acyl halides are used.

Subsequently, a hydrophilic polymer layer is formed on the polyamide active layer by using a coating solution including a hydrophilic polymer, an ionic strength adjusting salt, and water.

The salt for controlling the ionic strength may be a chloride, nitrate, sulfide, or acetate salt of an alkali metal or an alkaline earth metal having excellent solubility in water. Preferably, NaCl, Mg (NO ₃ ) ₂ .6H ₂ O, MgCl ₂ , MgSO ₄ , CaCl ₂ , and LiCl are used. These salts induce the precipitation of the hydrophilic polymer on the surface of the polymer membrane through ionic bonding with the functional group of the hydrophilic polymer dissolved together in the coating liquid to form a polymer layer.

The coating liquid preferably has an ionic strength of 0.01 to 1.0. The ionic strength is related to the amount of hydrophilic polymer precipitated in the coating solution. If the ionic strength is less than the above range, the formation of the hydrophilic polymer layer is insignificant. On the contrary, if the ionic strength exceeds the above range, all the pores on the surface of the polymer membrane are blocked, resulting in membrane performance. There is a problem of this deterioration.

At this time, the concentration of the hydrophilic polymer contained in the coating solution is preferably 100 to 50,000 ppm. If the concentration is lower than the lower limit, the uniformity of the coating is lowered, and the performance of the produced film is not constant. If the concentration exceeds the upper limit, the pores on the surface of the polymer membrane are clogged to deteriorate the performance of the film.

The coating solution may be coated on the polymer membrane by a commonly used dip coating, bar coating, spray coating, flow coating, or the like. The coating is carried out for 10 seconds to 1 hour, preferably 1 to 10 minutes.

In order to uniformly form the hydrophilic polymer layer on the surface of the polymer membrane, the polymer concentration, ionic strength, and coating time of the coating solution may be appropriately adjusted within the above range.

According to the method of the present invention, by modifying the surface characteristics of the polyamide reverse osmosis composite membrane through a relatively simple process, while maintaining the properties of salt rejection and permeation flow rate, at the same time satisfactory chlorine resistance and fouling resistance Reverse osmosis composite membranes can be prepared.

[Example]

Hereinafter, preferred embodiments of the present invention will be described. The following examples are described for the purpose of more clearly expressing the present invention, but the contents of the present invention are not limited to the following examples.

Example  1 to 3

Aqueous solution of 1,000 ppm polyvinyl alcohol (Polyvinylalcohol, Aldrich Co. Milwakee, MW = 89,000 ~ 98,000) using NaCl, 1,000 ppm polyvinyl sulfonic acid (Aldrich) Co. MW = 6,000) An aqueous solution, 1,000 ppm of polyethyleneimine (Polyethylenimine, Aldrich Co. Milwakee, MW = 750,000) having an ionic strength of 0.1 was prepared. Thereafter, the polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was dip-coated with each aqueous solution for 3 minutes at room temperature (about 24 ± 1 ℃) and dried at 60 ℃ for 10 minutes to obtain a composite membrane.

After the obtained composite membrane was fixed at room temperature by using a positive contact angle measurement method, 1 μl of distilled water was dropped on the membrane surface, and the angle formed by the membrane and water droplets was determined by NRL C.A. Measurement was performed using GONIMETER (rame'-hart, inc., U.S.A.).

Figure 2 is a graph showing the results of measuring the contact angle (Contact angle) in order to observe the film surface change before and after the polymer coating.

Referring to FIG. 2, the contact angle of the reverse osmosis membrane before coating was 78.0 °, indicating hydrophobicity. However, the membrane coated with polyethyleneimine (Example 3) exhibited a low contact angle of 44.1 °. It also showed a contact angle of 53.8 ° after coating (Example 2). The membrane coated with polyvinyl alcohol (Example 1) exhibited a contact angle of 64.4 °. This means that due to the formation of the coating layer of the present invention, the hydrophilicity of the membrane may be increased, thereby increasing the membrane permeability.

Example  4

A 1,000 ppm aqueous solution of polyethyleneimine (Polyethylenimine, Aldrich Co. Milwakee, MW = 750,000) having an ionic strength of 0.1 was prepared using Mg (NO ₃ ) _{2 ·} 6H ₂ O, and a polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared. 10 seconds, 30 seconds, and 60 seconds were dip-coated at room temperature (about 24 ± 1 ° C.), followed by drying at 60 ° C. for 10 minutes to obtain a composite membrane.

Chlorine resistance test was carried out by cutting the obtained composite membrane to the size of membrane cell and different immersion time in 3,450ppm aqueous solution of sodium hypochlorite (8% NaOCl, JUNSEI). The pH of the 3,450 ppm aqueous sodium hypochlorite solution was 9.8 and the temperature was the same at 25 ° C. After dipping, the NaOCl solution remaining on the surface of the composite membrane was thoroughly washed with distilled water and measured. The resistance of the composite membrane to chlorine was expressed in ppmh.

Permeability was calculated by measuring the permeation time (L / m ² · hr) per unit time, unit area, and salt removal rate was calculated by measuring the total dissolve solubility (TDS) of the feed water and production water. As for the permeation performance evaluation of the conventional reverse osmosis membrane for seawater desalination, 55 bar, 35,000 ppm aqueous NaCl solution, and 25 ° C are generally applied. In the present invention, the performance of the membrane was prepared by preparing a 100 ppm NaCl aqueous solution, the driving pressure was 60 psi, the flow rate of the feed water passing through the cell was fixed at 3.2 L / min. The results are shown in Table 1 below.

PEI 1,000 ppm I · S = 0.1 (Mg (NO ₃ ) ₂ · 6H ₂ O) Coating time 0 sec 10 seconds 30 seconds 60 seconds Chlorine Resistance Time 7.5 hours 9.2 hours 9.56 hours 10 hours Chlorine resistance increase rate 0% 18.5% 21.5% 25%

3 is a graph showing the results of measuring the chlorine resistance of the TFC polyamide film before coating treatment. At 3,450ppm NaOCl, chlorine resistance before coating can be seen up to 26,000ppm-hr. This translates to more than 90% salt removal rate for 7.5 hours at 3450 ppm NaOCl. Salt removal rate tends to decrease with time, but on the contrary, permeability increases in inverse proportion to salt removal rate. This tendency indicates that the -NH group present on the surface of the TFC polyamide film is unstable to chlorine.

4 to 6 show the results of permeation tests using 100 ppm NaCl aqueous solution for a composite membrane prepared by coating a 1000 ppm aqueous polyethyleneimine solution for 10 seconds, 30 seconds, and 60 seconds, respectively.

As shown in Figs. 4 to 6, the resistance test of chlorine shows that the resistance of all membranes coated with polyethyleneimine is greatly improved, which is 9.2 hours for 10 seconds, 9.56 hours for 30 seconds, and 10 hours for 60 seconds. The salt removal rate of 90% was maintained, which showed improved chlorine resistance of 18.5%, 21.5%, and 25%, respectively, compared to the uncoated membrane.

Example  5

NaCl was used to prepare a 1,000 ppm aqueous solution of polyethyleneimine (Polyethylenimine, Aldrich Co. Milwakee, MW = 750,000) with an ionic strength of 0.1, and a polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared at room temperature (about 24 ± 1 ° C). 10 seconds, 30 seconds, and 60 seconds were dip-coated respectively and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

Evaluation of the chlorine resistance of the prepared composite membrane is shown in Table 2 below.

PEI 1,000 ppm IS = 0.1 (NaCl) Coating time 0 sec 10 seconds 30 seconds 60 seconds Chlorine Resistance Time 7.5 hours 10.1 hours 11.8 hours 15.6 hours Chlorine resistance increase rate 0% 25.7% 36.4% 51%

7 to 9 show the results of permeation tests using 100 ppm NaCl aqueous solution for a composite membrane prepared by coating a 1000 ppm aqueous polyethyleneimine solution for 10 seconds, 30 seconds, and 60 seconds, respectively.

7 to 9, 90% salt removal was maintained for 10.1 hours for 10 seconds, 11.8 hours for 30 seconds, and 15.6 hours for 60 seconds, resulting in 25.7% and 36.4, respectively. %, 51% improved chlorine resistance was confirmed.

Example  6

NaCl was used to prepare 1,000 ppm aqueous solution of polyethyleneimine (Polyethylenimine, Aldrich Co. Milwakee, MW = 750,000) with an ionic strength of 0.2, and a polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared at room temperature (about 24 ± 1 ° C). 10 seconds, 30 seconds, and 60 seconds were dip-coated respectively and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 3 below.

PEI 1,000 ppm IS = 0.2 (NaCl) Coating time 0 sec 10 seconds 30 seconds Chlorine Resistance Time 7.5 hours 14.81 hours 14.5 hours Chlorine resistance increase rate 0% 49% 48.2%

10 and 11 are the results of the permeation test using a 100 ppm NaCl aqueous solution of the composite membrane prepared by coating a 1000 ppm aqueous polyethyleneimine solution for 10 seconds, 30 seconds respectively.

As shown in Fig. 10 and 11, 90% salt removal rate was maintained for 14.81 hours for 10 seconds coating, 14.5 hours for 30 seconds coating, 49%, 48.2% improved chlorine resistance compared to the uncoated film, respectively Indicated.

Example  7

NaCl was used to prepare an aqueous solution of 2,000 ppm polyethyleneimine (Polyethylenimine, Aldrich Co. Milwakee, MW = 750,000) with an ionic strength of 0.1, and the polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared at room temperature (about 24 ± 1 ° C). After dip coating for 10 seconds and dried at 60 ℃ for 10 minutes to obtain a composite membrane.

     To evaluate the chlorine resistance of the prepared composite membrane it is shown in Table 4 below.

PEI 2,000 ppm IS = 0.1 (NaCl) Coating time 0 sec 10 seconds Chlorine Resistance Time 7.5 hours 13 hours Chlorine resistance increase rate 0% 42.3%

12 is a result of a permeation test of a composite membrane prepared by coating a 2,000 ppm aqueous polyethyleneimine solution for 10 seconds using a 100 ppm NaCl aqueous solution.

Referring to FIG. 12, the salt removal rate was 90% for 13 hours when the coating was performed for 10 seconds, thereby showing an improved chlorine resistance of 42.3%.

Looking at the above results, it was confirmed that the formation of the coating layer is proportional to the effect of the salt and the coating time, the concentration of the coating solution. When the reverse osmosis membrane surface was coated with PEI, it was confirmed that the salting effect of NaCl was superior to that of Mg (NO ₃ ) ₂ · 6H ₂ O. In addition, as the coating time increased, the chlorine resistance was improved, but in the case of initial permeability, the permeability of the membrane coated with NaCl was less than that of the membrane controlled by Mg (NO ₃ ) ₂ · 6H ₂ O. This may be due to the salting effect of the polymer during coating, which is caused by the precipitated polymer blocking the surface pores of the membrane.

Example  8

NaCl was used to prepare an aqueous 1000 ppm polyvinyl sulfonic acid (Aldrich Co. MW = 6,000) solution with an ionic strength of 0.1, and the polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared at room temperature (about 24 ± 1). 10 seconds, 30 seconds, 60 seconds, each dip-coated and then dried at 60 ℃ for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 5 below.

PVSA 1,000 ppm IS = 0.1 (NaCl) Coating time 0 sec 10 seconds 30 seconds 60 seconds Chlorine Resistance Time 7.5 hours 12.1 hours 12.7 hours 12.73 hours Chlorine resistance increase rate 0% 38% 40.9% 41%

13 to 15 are A composite membrane prepared by coating polyvinylsulfonic acid 1,000 ppm aqueous solution for 10 seconds, 30 seconds, and 60 seconds, respectively, was subjected to a permeation test using 100 ppm NaCl aqueous solution.

13 to 15, 90% salt removal was maintained for 12.1 hours for 10 seconds coating, 12.7 hours for 30 seconds coating, and 12.73 hours for 60 seconds coating, and 38%, respectively, compared to the uncoated film. 40.9%, 41% improved chlorine resistance was confirmed.

Example  9

A 1,000 ppm aqueous polyvinyl sulfonic acid (Aldrich Co. MW = 6,000) aqueous solution having an ionic strength of 0.1 was prepared using Mg (NO ₃ ) _{2 ·} 6H ₂ O, and a polyamide reverse osmosis membrane for water purifier (Woongjin) Coway) was dip-coated at room temperature (about 24 ± 1 ℃) for 10 seconds and dried at 60 ℃ for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 6 below.

PVSA 1,000 ppm I · S = 0.1 (Mg (NO ₃ ) ₂ · 6H ₂ O) Coating time 0 sec 10 seconds Chlorine Resistance Time 7.5 hours 14.2 hours Chlorine resistance increase rate 0% 47.2%

FIG. 16 shows the results of permeation testing of a composite membrane prepared by coating a 1000 ppm aqueous polyvinylsulfonic acid solution for 10 seconds using an aqueous 100 ppm NaCl solution. It was compared with FIG. 13 to see the effect on the difference in salt.

Referring to FIG. 16, the salt removal rate was maintained at 90% for 14.2 hours. Compared with FIG. 13, in which the ionic strength was adjusted with NaCl, the effect of Mg (NO ₃ ) _{2 ·} 6H ₂ O was greater when polyvinylsulfonic acid was coated.

Example  10 to 11

Mg (NO ₃ ) _{2 ·} 6H ₂ O and NaCl were used to prepare 2,000 ppm polyvinyl sulfonic acid (Aldrich Co. MW = 6,000) aqueous solution having an ionic strength of 0.1, respectively. Amide reverse osmosis membrane (Woongjin Coway) was dip-coated at room temperature (about 24 ± 1 ° C.) for 10 seconds, and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 7 below.

PVSA 2,000ppm IS = 0.1 (10 seconds coating) Ion strength type Chlorine Resistance Time Chlorine resistance increase rate Mg (NO ₃ ) ₂ · 6H ₂ O 16 hours 53.1% NaCl 14 hours 46.4%

FIG. 17 and FIG. 18 show a composite membrane using 2,000 ppm aqueous polyvinylsulfonic acid prepared using Mg (NO ₃ ) _{2 ·} 6H ₂ O and NaCl as salts for ion control, and using 100 ppm NaCl aqueous solution. This is the result of the permeation test.

Referring to FIGS. 17 and 18, unlike polyethylenimine coating, the effect of Mg (NO ₃ ) _{2 ·} 6H ₂ O was greater than that of NaCl in polyvinylsulfonic acid coating.

Example  11

Mg (NO ₃ ) _{2 ·} 6H ₂ O and NaCl were used to prepare 2,000 ppm polyvinyl sulfonic acid (Aldrich Co. MW = 6,000) aqueous solution having an ionic strength of 0.1, respectively. The amide reverse osmosis membrane (Woongjin Coway) was dip-coated at room temperature (about 24 ± 1 ° C.) for 60 seconds and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 8 below.

PVSA 2,000 ppm IS = 0.1 (Mg (NO ₃ ) ₂ · 6H ₂ O) Coating time 0 sec 60 seconds Chlorine Resistance Time 7.5 hours 15.9 hours Chlorine resistance increase rate 0% 52.8%

19 is a result of a permeation test of a composite membrane prepared by coating a polyvinylsulfonic acid 2,000 ppm aqueous solution for 60 seconds using a 100 ppm NaCl aqueous solution. The coating of polyvinylsulfonic acid resulted in an increase in chlorine resistance time from 7.5 hours to 15.9 hours and an increase in chlorine resistance up to 52.8%.

Example  12

Mg (NO ₃ ) _{2 ·} 6H ₂ O was used to prepare an aqueous solution of 3,000 ppm polyvinyl sulfonic acid (Aldrich Co. MW = 6,000) having an ionic strength of 0.1, respectively, and a polyamide reverse osmosis membrane for water purifier ( Woongjin Coway) was dip-coated at room temperature (about 24 ± 1 ° C.) for 10 seconds and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 9 below.

PVSA 3,000 ppm IS = 0.1 (Mg (NO ₃ ) ₂ · 6H ₂ O) Coating time 0 sec 10 seconds Chlorine Resistance Time 7.5 hours 16.6 hours Chlorine resistance increase rate 0% 54.8%

20 is a result of performing a permeation test on a composite membrane prepared by coating a polyvinyl sulfonic acid 3,000 ppm for 10 seconds using an aqueous 100 ppm NaCl solution.

Referring to FIG. 20, after 16.6 hours, the salt removal rate of the film dropped to 90% or less, indicating that the chlorine resistance was improved in proportion to the coating concentration, the coating time, and the salt.

Example  13

Using NaCl, an aqueous solution of 2,000 ppm polyvinyl alcohol (Polyvinylalcohol, Aldrich Co. Milwakee, MW = 89,000 ~ 98,000) having an ionic strength of 0.1 was prepared. ℃) was dip-coated for 10 seconds and then immersed in glutaraldehyde to crosslinking reaction for 1 hour and dried at 60 ℃ for 10 minutes to obtain a composite membrane.

Chlorine resistance of the prepared composite membrane was evaluated and shown in Table 10 below.

PVA 2,000 ppm IS = 0.1 (NaCl), GA 1 hour reaction Coating time 0 sec 10 seconds Chlorine Resistance Time 7.5 hours 10.3 hours Chlorine resistance increase rate 0% 27.2%

FIG. 21 shows the results of conducting chlorine resistance experiments after preparing a membrane through crosslinking with glutaraldehyde after coating with 2,000 ppm aqueous polyvinyl alcohol.

Referring to FIG. 21, the salt removal rate of 90% was maintained for 10.3 hours, but thereafter, a rapid decrease in salt excretion rate and increase in permeability showed that the coating of polyvinyl alcohol did not significantly affect the improvement of chlorine resistance. Lose.

Example  14

2,000ppm polystyrene sulfonic acid (PSSA, MW = 70,000), polyvinylamine (PVAM, MW = 340,000), polyvinyl alcohol (Polyvinylalcohol, Aldrich Co. Milwakee, MW = 89,000 ~ 98,000) Each was prepared, and the polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was dip-coated at room temperature (about 24 ± 1 ° C.) for 5 minutes, and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

The composite membrane was subjected to a permeation test for 9 hours at 8 atm in 100 ppm bovine Serum Albumin solution to evaluate fouling resistance, which is shown in Table 11 below.

 Flux% 1hr 2 hr 3hr 4hr 5hr 6hr 7hr 8hr 9hr None-coating 100 86.8 78 73.3 71.3 71.1 70.2 68.9 66.4 PVA 100 85.9 80 80 75.3 74.4 74.4 70.3 70.3 PVAm 100 93.4 91.6 84.3 80.4 80.4 77.4 75.6 74.1 PSSA 100 93.3 90 90.7 85.1 84.1 82.8 81 81.2

Figure 22 shows the resistance time to serum serum albumin contamination of the composite membrane prepared by coating with polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.

As shown in Figure 22, the coating of polystyrene sulfonic acid increased the stain resistance from 66.4% to 81%, bringing about 14.6% increase effect.

Example  15

2,000 ppm polystyrene sulfonic acid (PSSA, MW = 70,000), polyvinylamine (polyvinylamine: PVAM, MW = 340,000) and polyvinyl alcohol aqueous solution were prepared, and a polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was prepared. Dip coating was performed at room temperature (about 24 ± 1 ° C.) for 5 minutes and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

 The prepared composite membrane was evaluated for fouling resistance using a 100 ppm sodium alginic acid solution, which is shown in Table 12 below.

1hr 2 hr 3hr 4hr 5hr 6hr 7hr 8hr 9hr None-coating 100 87.7 79.4 74.6 69.4 68.4 66.1 64.5 64.3 PSSA 100 95.5 90.8 86.6 81.8 75.8 74.8 74.5 70.7 PVA 100 90.8 85.4 84.2 80.1 78 75.3 70.8 70.8 PVAm 100 90.4 90.2 88.4 88.4 82.3 80.8 77.5 75.3

Figure 23 shows the resistance time to sodium alginate salt contamination of the composite membrane prepared by coating with a polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.

Referring to FIG. 23, the contamination resistance of the polyvinylamine aqueous solution was increased from 66.3% to 75.3%, resulting in an increase of about 11%.

Example  16

2,000ppm polystyrene sulfonic acid (PSSA, MW = 70,000), polyvinylamine (PVAM, MW = 340,000), polyvinyl alcohol (Polyvinylalcohol, Aldrich Co. Milwakee, MW = 89,000 ~ 98,000) Each was prepared, and the polyamide reverse osmosis membrane (Woongjin Coway) for water purifier was dip-coated at room temperature (about 24 ± 1 ° C.) for 5 minutes, and then dried at 60 ° C. for 10 minutes to obtain a composite membrane.

 The prepared composite membrane was evaluated for contamination resistance using a 100 ppm humic acid solution, which is shown in Table 13 below.

Flux 1hr 2 hr 3hr 4hr 5hr 6hr 7hr 8hr 9hr None-coating 100 93.5 88.9 85.9 84 83.2 82.8 81 78.4 PSSA 100 98.4 93.3 92.4 88.9 86 83.1 81.8 81.8 PVA 100 96.5 95.9 91.8 89.9 88.6 88.3 84.5 82.6 PVAm 100 98.5 98 97.7 96.2 96.2 94.4 94.4 95.2

Figure 24 shows the resistance time to humic acid contamination of the composite membrane prepared by coating with a polyvinyl alcohol, polyvinylamine, polystyrene sulfonic acid 2,000ppm aqueous solution.

Referring to FIG. 24, the polyvinylamine coating increased the stain resistance of the composite membrane from the existing 78.4% to 95.2%, resulting in an increase of about 16.8%.

Example  17

Prepare 2,000ppm polyvinylamine (polyvinylamine: PVAM, MW = 340,000) aqueous solution, and dipcoat polyamide reverse osmosis membrane (Woongjin Coway) for water purifier at room temperature (about 24 ± 1 ℃) for 5 minutes, respectively, and then 60 ℃. Dried for 10 minutes to obtain a composite membrane.

 The prepared composite membrane was evaluated for fouling resistance using a 100 ppm bovine Serum Albumin solution. After the evaluation, the surface change of the composite film was observed with a scanning electron microscope (SEM), and the results are shown in FIG. 25.

As shown in FIG. 25, it was confirmed that the contamination of the composite membrane coated with polyvinylamine was reduced as compared with the uncoated membrane.

2: porous support
4: polyamide active layer
6: hydrophilic polymer layer
10: composite membrane

Claims (10)

A porous support;
A polyamide active layer formed on the porous support; And
Anionic or cationic hydrophilic polymer layer made of polystyrenesulfonic acid or polyvinylamine formed on the active layer
Chlorine and fouling resistant polyamide reverse osmosis composite membrane comprising a. delete delete The porous support according to claim 1, wherein the porous support
Polysulfone, polyisulfone, polyimide, polyethylene, polypropylene, polyamide, polyimide, polyacrylonitrile, polymethyl methacrylate, and polyvinylidene fluoride A composite membrane comprising. The method of claim 1, wherein the polyamide active layer
A composite membrane formed by interfacial polymerization of a polyfunctional amine and an amine reactive compound selected from the group consisting of polyfunctional acyl halides, polyfunctional sulfonyl halides, and polyfunctional isocyanates. 1) a polyamide active layer is formed by interfacial polymerization of a porous support and a polyfunctional amine and an amine reactive compound on the porous support,
2) forming an anionic or cationic hydrophilic polymer layer on the polyamide active layer by using a coating solution containing polystyrene sulfonic acid or polyvinylamine, ionic strength adjusting salt and water
A method for producing the chlorine resistant and fouling resistant polyamide reverse osmosis composite membrane of claim 1. The method of claim 6 wherein the polyfunctional amine is
1,4-phenylenediamine, 1,3-phenylenediamine, 2,5-diaminotoluene, N, N'-diphenylethylene diamine, 4-methoxyphenylenediamine and mixtures thereof It is one kind of manufacturing method. The method of claim 6, wherein the multifunctional acyl halide is
Terephthaloyl chloride, isophthaloyl chloride, and mixtures thereof. The method according to claim 1, delete The method of claim 6, wherein the ion intensity control salt
NaCl, Mg (NO ₃ ) ₂ · 6H ₂ O, MgCl ₂ , MgSO ₄ , CaCl ₂ And LiCl It is one kind selected from the group consisting of.

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