KR102547346B1 - Excellent removing nitrate polyamide reverse osmosis membrane, method of manufacturing the same and membrane module comprising the same - Google Patents

Abstract

The present invention relates to a reverse osmosis membrane used in a household water purifier, wherein a polyfunctional amine and a compound reacting thereto are reacted to form a primary coating layer, and a specific amine compound is used to form a secondary coating layer on the surface of the primary coating layer. , Reverse osmosis membrane with high nitrate nitrogen removal rate and excellent nitrate nitrogen removal rate even under raw water conditions with high hardness-inducing components by imparting a low surface negative charge concentration, a separation membrane module including the same, and a manufacturing method thereof.

Description

Reverse osmosis membrane with excellent nitrate nitrogen removal rate, manufacturing method thereof, and membrane module including the same

The present invention relates to a reverse osmosis membrane used in household water purifiers, etc., and more particularly, to a reverse osmosis membrane with a low surface negative charge and excellent nitrate nitrogen removal rate even under raw water conditions with a high content of substances causing hardness, a method for manufacturing the same, and a method for manufacturing the same It relates to a separation membrane module comprising

In general, methods for separating various components such as fine impurities and ions present in a liquid include an evaporation method, an electrodialysis method, a microfiltration method, an ultrafiltration method, a reverse osmosis method, and the like. Among them, the reverse osmosis method has the advantage of low energy consumption, the construction of small as well as large-sized facilities, and the ability to remove monovalent ions in water.

In general, the separation membrane used in the reverse osmosis method includes a nano-membrane or a reverse osmosis membrane. Among them, the reverse osmosis membrane is composed of a support layer for maintaining mechanical strength and an active layer having selective permeability. Recently, aromatic polysulfone is used as a porous support layer. Reverse osmosis membranes composed of polyamide as an active layer are being developed and commercialized. Methods for manufacturing the reverse osmosis membrane include a thin layer dispersion method, a dip coating method, a vapor deposition method, a Langmuir-Blodgett method, an interfacial polymerization method, and the like, and the most commonly used method is Cadotte It is an interfacial polymerization method disclosed by [U.S. Patent No. 4,277,344]. The above invention discloses a technique related to an aromatic polyamide composite film obtained by interfacial polymerization of an aromatic polyfunctional amine containing at least two primary amine substituents and an aromatic acyl halide containing at least three acyl halide substituents.

However, in the reverse osmosis membrane obtained through the interfacial polymerization method, unreacted acyl halide substituents inevitably remain on the surface of the reverse osmosis membrane after the reaction is completed, and the residual acyl halide substituents are hydrolyzed through a water washing process after interfacial polymerization. It turns into a carboxylic acid group. This mechanism can be explained as the reason why the surface of a common polyamide reverse osmosis membrane is negatively charged. This surface negative charge characteristic causes the accumulation of high divalent ions on the surface of the membrane through electrostatic attraction, especially when raw water with a high concentration of divalent cation components is treated, and the reason why the removal rate of nitrate nitrogen is ultimately reduced is that do.

US Patent Registration No. 4277344 (registration date: 1981.07.07)

The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to perform coating with a specific amine compound after polyamide polymerization, even under raw water conditions containing a high level of hardness component concentration. It is an object of the present invention to provide a reverse osmosis membrane with a minimized acid nitrogen removal rate and an excellent nitrate nitrogen removal rate and a manufacturing method thereof.

The reverse osmosis membrane with excellent nitrate nitrogen removal rate of the present invention for solving the above problems includes a porous support; And a polyamide layer formed on at least one side of the porous support; to a reverse osmosis membrane comprising: filtering potable water containing 600 ppm of a hardness-inducing substance and 30 ppm of nitrate nitrogen with the reverse osmosis membrane. ), the removal rate of nitrate nitrogen in the treated water is 80 to 85%, and the size of the surface charge can satisfy the following condition (1).

(1) Under pH 6.5 ~ 7.5 conditions, -25mV to -22mV

As a preferred embodiment of the present invention, the surface charge of the reverse osmosis membrane may satisfy the following conditions (2) to (3).

(2) Under pH 5 conditions, -10mV to -4.5mV

(3) Under pH 6 conditions, -22mV to -10mV

As a preferred embodiment of the present invention, the polyamide layer is a primary coating film formed by reacting a polyfunctional amine compound and a polyfunctional acid halide compound; and a second coating layer formed on the upper surface of the first coating layer.

As a preferred embodiment of the present invention, the secondary coating film is a film formed by reacting a polyfunctional acid halide compound and an amine compound, and the amine compound is one selected from a compound represented by Formula 1 and a compound represented by Formula 2 May include more than one species.

[Formula 1]

In Formula 1, R ₁ is an alkyl group having 1 to 3 carbon atoms:

[Formula 2]

In Formula 2, R ₂ is an alkylene group having 1 to 5 carbon atoms.

As a preferred embodiment of the present invention, the porous support is a non-woven fabric; and a porous polymer layer, wherein the porous polymer layer includes at least one selected from polysulfone resin, polyethersulfone resin, polyimide resin, polypropylene resin, and polyvinylidene fluoride resin, and the porous support may have an average thickness of 100 to 500 μm and an average pore size of 1 to 500 nm.

As a preferred embodiment of the present invention, the amine compound may include the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 in a weight ratio of 1:0.6 to 1:1.0.

As a preferred embodiment of the present invention, the material causing hardness may include at least one material selected from calcium and magnesium.

For another object of the present invention, a membrane module including the reverse osmosis membrane described above may be manufactured.

As another object of the present invention, a method for manufacturing a reverse osmosis membrane with excellent nitrate nitrogen removal rate is to coat a porous support with a first solution containing a polyfunctional amine compound and a second solution containing a polyfunctional acid halogen compound in turn. Level 1; A second step of spraying air to the porous support having performed step 1 to remove excess solution and thermally crosslinking it to form a first coating film on at least one surface of the porous support; A third step of coating the surface of the first coating film with a third solution containing 0.005 to 0.10% by weight of an amine compound to form a second coating film; and a fourth step of removing residual acids or unreacted substances on the surface of the secondary coating film.

As a preferred embodiment of the present invention, the amine compound may include at least one selected from a compound represented by Formula 1 and a compound represented by Formula 2 below.

[Formula 1]

In Formula 1, R ₁ is an alkyl group having 1 to 3 carbon atoms:

[Formula 2]

In Formula 2, R ₂ is an alkylene group having 1 to 5 carbon atoms.

Under the condition of raw water containing high hardness components through the present invention, a reverse osmosis membrane that minimizes the decrease in nitrate nitrogen removal rate caused by the charge shielding effect on the surface of the membrane and the mechanism of charge-induced pore size expansion and a membrane module including the same It can be manufactured, and when designing a water purifier system, there is an effect of enabling more economical water purifier operating conditions to be set by increasing the design margin of operating factors that directly affect the removal rate, such as operating pressure and recovery rate.

1 is a graph showing the surface charge concentration of Examples 1 to 3 and Comparative Example 1 according to pH.

In the present invention, a separation membrane and a method for manufacturing the same are proposed that minimize the decrease in nitrate nitrogen removal rate that may occur under raw water conditions with a high concentration of hardness components and mitigate the problem of deterioration in membrane performance as much as possible.

In the present invention, the separation membrane is applied to a reverse osmosis membrane, but it is not limited to the type of separation membrane and can be applied to various separation membranes such as nanofiltration membranes.

Hereinafter, the reverse osmosis membrane with excellent nitrate nitrogen removal rate of the present invention will be described in detail.

The reverse osmosis membrane may include a porous support; and a polyamide layer formed on at least one side of the porous support.

At this time, the porous support is a non-woven fabric; and a porous polymer layer formed on at least one surface of the nonwoven fabric.

In addition, the porous support is a typical microporous support, and is not particularly limited, but the size of the pores must be large enough to allow permeate to pass through while not interfering with the formation of a thin film on the porous support.

In order to satisfy these conditions, the porous support may preferably have an average thickness of 40 to 500 μm, preferably 80 to 300 μm. If the average thickness is less than 40㎛, the physical strength of the separator is low, and there may be a problem of defects due to damage to the separator in the post-processing process for elementization, and if it exceeds 500㎛, the water permeability is lowered and There may be a problem of reducing the performance of .

In addition, the porous support may have an average pore size of 1 to 500 nm, preferably 10 to 450 nm, and more preferably 50 to 400 nm. If the pores of the porous support exceed 500 nm, since the ultra-thin film is sunk into the pores, a desired flat sheet structure may not be formed.

In more detail about the porous support, the nonwoven fabric may be used without limitation as long as it is a nonwoven fabric of specifications commonly used in the art, and is preferably one selected from polyester nonwoven fabric, polyethylene nonwoven fabric, and polypropylene nonwoven fabric. may contain more than

In addition, the thickness of the nonwoven fabric may be 30 to 300 μm, preferably 50 to 200 μm. If the thickness of the nonwoven fabric is out of the above range, there may be a problem in that permeation flow rate decreases.

On the other hand, the porous polymer layer may preferably be formed on one side of the porous support, and may be a porous polymer layer formed of commonly available materials, preferably polyester resin, polysulfone resin, polyethersulfone It may be formed by including at least one selected from resin, polyimide resin, polypropylene resin, and polyvinylidene fluoride resin.

In addition, the average thickness of the porous polymer layer may be 10 to 200 μm, preferably 30 to 190 μm. If the average thickness of the porous polymer layer is out of the above range, the water permeability is lowered, which may cause difficulty in increasing the effect.

On the other hand, the polyamide layer is a primary coating film; and a second coating film formed on the surface of the first coating film.

Specifically, the first coating film may be a film formed by interfacial polymerization of a polyfunctional amine compound and a polyfunctional acid halide compound, and the second coating film is grafted by reacting a polyfunctional acid halide compound and an amine compound. It may be a membrane, and through the grafting, the negative charge concentration on the surface of the separator is reduced, and finally, the electrostatic attraction with the divalent cation hardness material is reduced, thereby minimizing the accumulation of divalent cations on the surface of the separator.

In this case, the polyfunctional amine compound and the polyfunctional acid halide compound will be described in a manufacturing method to be described later.

On the other hand, in the case of forming the secondary coating film as described above, if the secondary coating film is not formed, the unreacted acyl halide remaining on the surface of the primary coating film is hydrolyzed through a water washing process to form carboxylic acid. may change, and eventually there may be a problem with a lower surface charge value (a higher surface negative charge value).

In addition, the amine compound for forming the secondary coating may include at least one selected from a compound represented by Formula 1 and a compound represented by Formula 2 below, preferably a compound represented by Formula 1 and Both of the compounds represented by Formula 2 may be included. In particular, when two compounds represented by Formulas 1 and 2 are used, the ability to remove nitrate nitrogen is more excellent under nitrate nitrogen alone conditions and nitrate nitrogen, water, and hardness-inducing substances conditions than when one compound is included. It may work.

In addition, the amine compound may include a compound represented by Formula 1 and a compound represented by Formula 2 at a weight ratio of 1:0.6 to 1:1.0, preferably at a weight ratio of 1:0.7 to 1:0.9. can

If the weight ratio is out of range, there may be a problem in that nitrate nitrogen removal ability is lowered or the surface negative charge reduction effect is lowered.

[Formula 1]

In Formula 1, R ₁ may be an alkyl group having 1 to 3 carbon atoms, preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 2 carbon atoms. If the number of carbon atoms of R ₁ exceeds 3, steric hindrance occurs as the chain structure is excessively elongated, and accordingly, the reaction efficiency with unreacted acyl halide is rapidly lowered, resulting in a surface charge reduction effect and nitrate nitrogen There may be a problem that the improvement effect of the removal rate is reduced.

[Formula 2]

In Formula 2, R ₂ may be an alkylene group having 1 to 5 carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms. If the carbon number of R ₁ exceeds 5, steric hindrance occurs as the chain structure is excessively elongated, and accordingly, the reaction efficiency with unreacted acyl halide is rapidly lowered, resulting in a surface charge reduction effect and nitrate nitrogen There may be a problem that the improvement effect of the removal rate is reduced.

On the other hand, among domestic reverse osmosis water purifier certification items, the nitrate nitrogen test condition is a condition containing a hardness-inducing substance at a concentration of about 600 ppm. Due to the mechanism, the nitrate nitrogen removal rate is significantly lowered compared to the nitrate nitrogen alone test.

On the other hand, when the reverse osmosis membrane is immersed in a solution, the magnitude of the surface charge of the reverse osmosis membrane may vary according to the pH concentration of the solution, and the magnitude of the surface charge of the reverse osmosis membrane may satisfy the following condition (1) .

(1) Under pH 6.5 ~ 7.5 conditions, -25mV to -22mV

Specifically, when the reverse osmosis membrane is operated in a solution having a pH of 6.5 to 7.5, the surface charge of the reverse osmosis membrane may preferably be -24 mV to -23 mV.

In addition, the size of the surface charge of the reverse osmosis membrane may further satisfy the following conditions (2) to (3).

(2) Under pH 5 conditions, -10mV to -4.5Mv

At this time, under the condition of pH 5, the surface charge of the reverse osmosis membrane may be -10mV to -4.5mV, preferably -9mV to -5mV.

(3) Under pH 6 conditions, -22mV to -10mV

At this time, under the condition of pH 6, the surface charge of the reverse osmosis membrane may be -22mV to -10mV, preferably -24mV to -8mV.

On the other hand, when the reverse osmosis membrane is filtered in potable water containing 600 ppm of a hardness-inducing substance and 30 ppm of nitrate nitrogen, the nitrate nitrogen removal rate of the treated water may be 80 to 85%, preferably may be 81 to 84%.

At this time, the nitrate nitrogen removal rate may be measured through Equation 1 below.

[Equation 1]

Nitrate nitrogen removal rate = (initial nitrate nitrogen detection amount - nitrate nitrogen detection amount after operation)/initial nitrate nitrogen detection amount × 100 (%)

For another purpose of the present invention, a membrane module including the reverse osmosis membrane described above may be manufactured.

In addition, it is possible to manufacture a reverse osmosis water purifier including the separation membrane module, and when designing the reverse osmosis water purifier system, the operating conditions of the water purifier are more economical by increasing the design margin of operating factors that directly affect the removal rate, such as operating pressure and recovery rate. setting is possible.

As another object of the present invention, a method for manufacturing a reverse osmosis membrane with excellent nitrate nitrogen removal rate is to coat a porous support with a first solution containing a polyfunctional amine compound and a second solution containing a polyfunctional acid halogen compound in turn. Level 1; A second step of spraying air to the porous support having performed step 1 to remove excess solution and thermally crosslinking it to form a first coating film on at least one surface of the porous support; A third step of coating the surface of the first coating layer with a third solution containing an amine compound to form a second coating layer; and a fourth step of removing residual acids or unreacted substances on the surface of the secondary coating film.

In the manufacturing method described below, the same parts as the reverse osmosis membrane described above will be omitted and described.

Specifically, first, the first solution coating treatment of the first step may be performed for 5 seconds to 10 minutes, preferably for 20 seconds to 4 minutes.

In addition, the coating treatment of the first solution may be performed by various methods such as immersion, impregnation, and coating, and after application, excess solution may be removed from the support using rolling, sponge, air knife, or other appropriate means.

In this case, the first solution may include a multifunctional amine compound, an additive, and water.

Describing each component of the first solution, first, the polyfunctional amine compound may be included in an amount of 0.1 to 10% by weight, preferably 0.3 to 3% by weight, in the first solution.

In this case, the polyfunctional amine compound may be used without limitation as long as it is a known multifunctional amine compound, but more preferably, it may be metaphenylenediamine (MPD).

In addition, the additive may be at least one selected from ethylhexanediol (EHD), tetramethylhexadiamine (TMHD) and toluenesulfonic acid (TSA), preferably ethylhexanediol (EHD), tetramethylhexadia It may be one selected from min (TMHD) and toluene sulfonic acid (TSA).

At this time, the content of the additive may vary depending on the type of additive, but preferably may be included in 0.001 to 3.0% by weight, more preferably 0.005 to 2.5% by weight in the first solution. there is.

In addition, the solvent may be included in the remaining amount except for the polyfunctional amine compound and the additive in the first solution.

Next, the second solution coating treatment of the first step may be performed for 20 to 60 seconds, preferably for 25 to 55 seconds, and the coating treatment method is performed in the same manner as the first solution coating treatment. can do.

In this case, the second solution may include a polyfunctional acid halide compound and a solvent.

Specifically, the polyfunctional acid halide compound may be included in an amount of 0.005 to 5% by weight, preferably 0.01 to 0.5% by weight in the second solution.

In this case, the polyfunctional acid halide compound may include at least one selected from polyfunctional acyl halides, polyfunctional sulfonyl halides, and polyfunctional isocyanates, and may preferably be polyfunctional acyl halides. It may be at least one selected from dicarboxylic acid halides and tricarboxylic acid halides, and more preferred examples are trimesoyl chloride (TMC), isophthaloyl chloride (IPC) and terephthaloyl chloride (TPC) It may include one or more selected from among.

In addition, the solvent may be included in the second solution in a residual amount excluding the polyfunctional acid halide compound.

At this time, the solvent may be used without limitation as long as it is an organic solvent immiscible with water, but more preferably one or more selected from among halogenated hydrocarbons such as hexane, cyclohexane, heptane, alkanes having 8 to 12 carbon atoms and freons, More preferably, the solvent may include an alkane having 8 to 12 carbon atoms, and more preferably an alkane having 9 to 11 carbon atoms.

Next, in the second step of air injection, air is injected to the porous support having performed the second step at a pressure of 0.1 to 1.0 bar, preferably at a pressure of 0.3 to 0.8 bar for 5 to 20 seconds, preferably 8 Excess organic solution can be removed by spraying for ~17 seconds.

Next, the two-step thermal crosslinking may be performed at 40 to 80° C. for 30 seconds to 5 minutes, and preferably at 50 to 70° C. for 1 minute to 3 minutes.

Next, the third solution coating treatment of the above three steps may be performed for 5 seconds to 10 minutes, preferably 20 seconds to 2 minutes.

At this time, the coating treatment of the third solution may be performed by various methods such as impregnation, spray coating, etc., and preferably may be performed through spray coating.

Also, the third solution may include an amine compound and water.

Specifically, the amine compound may be included in an amount of 0.005 to 0.10% by weight, preferably 0.07 to 0.09% by weight, in the third solution. If the amine compound is included in an amount of less than 0.005% by weight, the efficiency of the secondary coating may decrease due to insufficient reaction with the unreacted acyl halide, and the nitrate nitrogen removal rate of the reverse osmosis membrane may decrease. , If it contains more than 0.10% by weight, the permeation flow rate and salt removal rate rapidly decrease, which may be unsuitable as a water purifier filter.

In addition, since the amine compound has been described in detail in the above-described portion related to the reverse osmosis membrane, it will be omitted.

Next, the removal of residual acid or unreacted substances in step 4 is performed by immersing for 1 to 3 hours in a solution containing 0.1 to 0.3% by weight of sodium carbonate, preferably 0.2 to 0.3% by weight and the remaining amount of water. can

Hereinafter, the present invention will be described through the following examples. At this time, the following examples are only presented to illustrate the invention, and the scope of the present invention is not limited by the following examples.

[Example]

Example 1: Preparation of reverse osmosis membrane

A porous support having an average pore size of 20 nm (±5 nm) was prepared by casting a polysulfone porous polymer layer having a thickness of 140 μm on one side of a polyester nonwoven fabric having an average thickness of 100 μm.

Next, the porous support was immersed in the first solution for 40 seconds and then immersed in the second solution for 1 minute.

At this time, the first solution was prepared by including 1.1% by weight of metaphenylenediamine (MPD) as a multifunctional amine, 0.2% by weight of ethylhexanediol (EHD) as an additive, and the remaining amount of water.

In addition, the second solution was prepared by including 0.1% by weight of trimesoyllochloride (TMC) and the remaining amount of cyclohexane (solvent).

Next, the excess solution (first solution and / or second solution) present on the surface of the porous support was removed by blowing air for 10 seconds under a pressure of 0.5 bar to the porous support having performed the above step, and 60 ° C. Thermal crosslinking was performed for 2 minutes under the condition to form a first coating film on the upper surface of the porous support.

Next, a second coating film was formed on the surface of the first coating film by spraying a third solution on the porous support on which the first coating film was formed for 20 seconds.

At this time, as the amine compound, a compound represented by Formula 1-1 and a compound represented by Formula 2-1 were used, and the third solution contained 0.025% by weight of the compound represented by Formula 1-1 and Formula 2- Including 0.020% by weight of the compound represented by 1 and the remaining amount of water, it was included in a weight ratio of 1: 0.8.

[Formula 1-1]

In Formula 1, R ₁ is an alkyl group having 1 carbon atom.

[Formula 2-1]

In Formula 2, R ₂ is an alkylene group having 3 carbon atoms.

Next, by performing the above steps, the porous support on which the first coating film and the second coating film are formed is immersed in a solution containing 0.2% by weight of sodium carbonate and the remaining amount of water for 2 hours, so that the acid or other substances remaining on the surface of the second coating film are immersed. The reactants were removed, and finally a reverse osmosis membrane was obtained.

Examples 2 to 9 and Comparative Examples 1 to 3: Preparation of reverse osmosis membrane

A reverse osmosis membrane was prepared in the same manner as in Example 1, but Examples 2 to 7 and Comparative Examples 1 to 3 were performed under the conditions shown in Tables 1 to 4 below.

In addition, Example 6 used 1.2% by weight of tetramethyl hexanediamine (TMHD) as an additive in the first solution, and Example 7 used toluene sulfonic acid (TSA) as an additive in the first solution. ) 1.32% by weight was used.

Comparative Example 4: Preparation of reverse osmosis membrane

A reverse osmosis membrane was prepared in the same manner as in Example 1, but as a third solution, 0.025% by weight of the compound represented by Formula 1-2 and 0.020% by weight of the compound represented by Formula 2-2 and the remaining amount of water were included in Comparative Example. 4 was carried out.

[Formula 1-2]

In Formula 1, R ₁ is an alkyl group having 5 carbon atoms.

[Formula 2-2]

In Formula 2, R ₂ is an alkylene group having 5 carbon atoms.

Comparative Examples 5 to 6: Preparation of reverse osmosis membrane

A reverse osmosis membrane was prepared in the same manner as in Example 1, but Comparative Examples 5 to 6 were performed under the conditions shown in Table 4 below.

Experimental Example 1: Measurement of flow rate and salt rejection of reverse osmosis membrane

The reverse osmosis membranes prepared in Examples 1 to 9 and Comparative Examples 1 to 6 were prepared in a sodium chloride (NaCl) aqueous solution (pH 7) at a concentration of 200 ppm for 30 minutes at a temperature of 25 ° C. and a pressure of 60 psi. After operation, the permeate flux and salt rejection were measured, and the results are shown in Tables 1 to 4 below.

Experimental Example 2: Measurement of nitrate nitrogen removal rate of reverse osmosis membrane

The reverse osmosis membranes prepared in Examples 1 to 9 and Comparative Examples 1 to 6 were operated for 30 minutes under conditions of 25 ° C. and 50 psi under conditions of nitric acid nitrogen alone and nitrate nitrogen certification test raw water conditions. After each nitrate nitrogen removal rate was measured, it is shown in Tables 1 to 4 below.

At this time, the "nitric acid nitrogen alone crude liquid condition" means filtering for 30 minutes under 30 ppm of nitrate nitrogen, and the "nitrate nitrogen certification test raw water condition" is the hardness-inducing substance (calcium and magnesium are 5: It means filtering for 30 minutes under the condition of raw water containing 600 ppm of nitrate nitrogen, 30 ppm of nitrate nitrogen, and the remaining amount of water.

In addition, the nitrate nitrogen removal rate was measured through Equation 1 below.

[Equation 1]

Nitrate nitrogen removal rate = (initial nitrate nitrogen detection amount - nitrate nitrogen detection amount after operation)/initial nitrate nitrogen detection amount × 100 (%)

Experimental Example 3: Surface charge measurement

The surface zeta potential of the reverse osmosis membranes prepared in Examples 1 to 9 and Comparative Examples 1 to 6 was measured at each of pH7, pH6, and pH5 using a surface charge measuring device (Anton Paar's Electrokinetic Analyzer). to analyze the surface charge. The measured values are shown in Tables 1 to 4 and FIG. 1 below.

Example 1 Example 2 Example 3 Example 4



manufacturing method
1st solution
(weight%) multifunctional amine compound MPD
1.1 additive EHD
0.2 EHD
0.2 EHD
0.2 EHD
0.2 water balance balance balance balance 2nd solution
(weight%) Polyfunctional Acid Halogen Compound TMC
0.1 TMC
0.1 TMC
0.1 TMC
0.1 menstruum balance balance balance balance
3rd solution
(weight%) amine
compound chemical formula
1-1(A) 0.025 0.025 - 0.004 chemical formula
2-1(B) 0.020 - 0.020 0.003 A:B weight ratio 1:0.8 - - 1:0.75 water balance balance balance balance


reverse osmosis
separator
basic conditions Flow (GFD) 24.1 26.9 28.9 29.1 Removal rate (%) 97.9 96.8 95.5 97.0 Nitrate nitrogen removal rate (%) nitrate nitrogen conditions 97.2 94.9 95.1 95.3 Nitrate Nitrogen + Water + Hardness Inducing Substance Conditions 84.2 78.3 76.8 79.2 surface
charge concentration
(mV) at pH7 condition -22.3 -24.0 -23.5 -23.7 at pH5 condition -4.6 -6.9 -7.9 -6.2 at pH6 condition -18.0 -19.0 -19.2 -18.8

Example 5 Example 6 Example 7 Example 8



manufacturing method
1st solution
(weight%) multifunctional amine compound MPD 1.1 additive EHD
0.2 TMHD
1.2 TSA
1.32 EHD
0.2 water balance balance balance balance 2nd solution
(weight%) Polyfunctional Acid Halogen Compound TMC
0.1 TMC
0.1 TMC
0.1 TMC
0.1 menstruum balance balance balance balance
3rd solution
(weight%) amine
compound chemical formula
1-1(A) 0.045 0.025 0.025 0.025 chemical formula
2-1(B) 0.045 0.020 0.020 0.0175 A:B weight ratio 1:1.0 1:0.8 1:0.8 1:0.7 water balance balance balance balance


reverse osmosis
separator basic condition Flow (GFD) 28.3 23.9 23.7 25.8 Removal rate (%) 97.3 98.1 97.7 97.6 Nitrate nitrogen removal rate (%) nitrate nitrogen conditions 95.8 96.8 97.0 96.1 Nitrate Nitrogen + Water + Hardness Inducing Substance Conditions 80.3 84.0 83.9 82.9 surface
charge concentration
(mV) at pH7 condition -22.9 -22.8 -22.9 -23.2 at pH5 condition -6.3 -4.8 -4.7 -5.8 at pH6 condition -18.6 -17.8 -18.1 -18.2

Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3



manufacturing method
1st solution
(weight%) multifunctional amine compound MPD
1.1 additive EHD
0.2 EHD
0.2 EHD
0.2 EHD
0.2 water balance balance balance balance 2nd solution
(weight%) polyfunctional acid halide compound TMC
0.1 TMC
0.1 TMC
0.1 TMC
0.1 menstruum balance balance balance balance
3rd solution
(weight%) amine
compound chemical formula
1-1(A) 0.025 - 0.001 0.07 chemical formula
2-1(B) 0.0225 - 0.001 0.06 A:B weight ratio 1:0.9 - 1:1.0 1:0.85 water balance 100 balance balance


reverse osmosis
separator basic conditions Flow (GFD) 23.5 32.9 31.1 18.5 Removal rate (%) 98.1 95.1 95.7 98.8 Nitrate nitrogen removal rate (%) nitrate nitrogen conditions 97.8 90.3 92.3 97.9 Nitrate Nitrogen + Water + Hardness Inducing Substance Conditions 84.9 65.0 71.5 85.6 surface
charge concentration
(mV) at pH7 condition -22.6 -30.5 -26.6 -22.0 at pH5 condition -4.9 -10.8 -8.1 -3.9 at pH6 condition -18.3 -21.3 -19.9 -17.5

Comparative Example 4 Comparative Example 5 Comparative Example 6



manufacturing method
1st solution
(weight%) multifunctional amine compound MPD
1.1 additive EHD
0.2 EHD
0.2 EHD
0.2 water balance balance balance 2nd solution
(weight%) polyfunctional acid halide compound TMC
0.1 TMC
0.1 TMC
0.1 menstruum balance balance balance 3rd solution
(weight%) amine
compound chemical formula
1-1(A) Formula 1-2
0.025 0.025 0.025 chemical formula
2-1(B) Formula 2-2
0.020 0.0075 0.0325 A:B weight ratio 1:0.8 1:0.3 1:1.3 water balance balance balance


reverse osmosis
separator basic condition Flow (GFD) 23.8 26.7 21.2 Removal rate (%) 97.2 95.6 98.5 Nitrate nitrogen removal rate (%) nitrate nitrogen conditions 91.5 94.2 98.1 Nitrate Nitrogen + Water + Hardness Inducing Substance Conditions 79.8 75.3 85.3 surface
charge concentration
(mV) at pH7 condition -22.5 -24.9 -25.5 at pH5 condition -4.8 -6.6 -5.5 at pH6 condition -18.3 -19.3 -19.5

Looking at Tables 1 to 4, Examples 1 to 9 are excellent in flow rate and salt removal rate under basic conditions after 30 minutes of operation, and nitrate nitrogen removal rate under nitrate nitrogen conditions and nitrate nitrogen and hardness-inducing substances. It was confirmed that the surface charge concentration was excellent and the surface charge concentration was greatly improved.

On the other hand, in Comparative Example 1 not using the amine compound including Chemical Formulas 1 and 2, it was confirmed that not only the nitrate nitrogen removal rate was remarkably poor, but also the surface charge concentration was very low.

In addition, in Comparative Examples 2 to 3 and Comparative Examples 5 to 6 in which the weight ratio of Chemical Formulas 1 and 2 is out of the scope of the present invention, the nitrate nitrogen removal rate is significantly lowered, the surface charge concentration is lowered, or the flow rate is It was confirmed that there was a problem that significantly deteriorated.

In addition, in the case of Comparative Example 4 using structures other than the structures of Formulas 1 and 2 of the present invention, it was confirmed that the ability to remove nitrate nitrogen was remarkably reduced.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

Claims (10)

A porous support comprising a non-woven fabric and a porous polymer layer; And a polyamide layer formed on at least one side of the porous support; relates to a reverse osmosis membrane comprising a,
The polyamide layer may include a primary coating film formed by reacting a polyfunctional amine compound and a polyfunctional acid halide compound; And a second coating film formed on the upper surface of the first coating film; includes,
The secondary coating film is a film formed by reacting a polyfunctional acid halide compound and an amine compound,
The amine compound includes a compound represented by Formula 1 and a compound represented by Formula 2 in a weight ratio of 1:0.6 to 1:1.0,
When potable water containing 600 ppm of a hardness-inducing substance and 30 ppm of nitrate nitrogen is filtered with the reverse osmosis membrane, the nitrate nitrogen removal rate of the treated water is 80 to 85%,
The reverse osmosis membrane is a reverse osmosis membrane with excellent nitrate nitrogen removal rate, in which the size of the surface charge satisfies the following condition (1).
(1) Under pH 6.5 ~ 7.5 conditions, -25mV to -22mV
[Formula 1]

In Formula 1, R ₁ is an alkyl group having 1 to 3 carbon atoms:
[Formula 2]

In Formula 2, R ₂ is an alkylene group having 1 to 5 carbon atoms.
The reverse osmosis membrane with excellent nitrate nitrogen removal rate according to claim 1, wherein the surface charge of the reverse osmosis membrane satisfies the following conditions (2) to (3).
(2) Under pH 5 conditions, -10mV to -4.5mV
(3) Under pH 6 conditions, -22mV to -10mV
delete delete According to claim 1,
The porous polymer layer includes at least one selected from polysulfone resin, polyethersulfone resin, polyimide resin, polypropylene resin, and polyvinylidene fluoride resin,
The porous support has an average thickness of 100 ~ 500㎛ and an average pore size of 1 ~ 500nm, characterized in that the nitrate nitrogen removal rate is excellent reverse osmosis membrane.
delete According to claim 1,
The reverse osmosis membrane with excellent nitrate nitrogen removal rate, characterized in that the hardness causing material comprises at least one material selected from calcium and magnesium.
A separation membrane module comprising the reverse osmosis membrane according to any one of claims 1, 2, 5, and 7.
A first step of sequentially coating a porous support with a first solution containing a polyfunctional amine compound and a second solution containing a polyfunctional acid halide compound;
A second step of spraying air to the porous support having performed step 1 to remove excess solution and thermally crosslinking it to form a first coating film on at least one surface of the porous support;
A third step of coating the surface of the first coating film with a third solution containing 0.005 to 0.10% by weight of an amine compound to form a second coating film; and
Step 4 of removing residual acid or unreacted substances on the surface of the secondary coating film; performing a process including,
The third solution includes a polyfunctional acid halide compound and an amine compound, and the amine compound of the third solution includes a compound represented by Formula 1 and a compound represented by Formula 2 in a weight ratio of 1:0.6 to 1:1.0, ,
In the reverse osmosis membrane prepared by performing step 4, when potable water containing 600 ppm of a hardness-inducing substance and 30 ppm of nitrate nitrogen is filtered through the reverse osmosis membrane, the nitrate nitrogen removal rate of the treated water is 80 to 85%,
The method of manufacturing a reverse osmosis membrane having an excellent nitrate nitrogen removal rate in which the size of the reverse osmosis membrane satisfies the following condition (1);
(1) Under pH 6.5 ~ 7.5 conditions, -25mV to -22mV
[Formula 1]

In Formula 1, R ₁ is an alkyl group having 1 to 3 carbon atoms:
[Formula 2]

In Formula 2, R ₂ is an alkylene group having 1 to 5 carbon atoms. delete

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