KR20130142329A - Reverse osmosis membrane with high flux and manufacturing method thereof - Google Patents

Abstract

The present invention is a reverse osmosis membrane comprising porous supporter and a polyamide based active layer formed in the upper part of the porous supporter. The polyamide based active layer comprises the compound indicated as [Chemical formula 1]. In the chemical formula 1, R is C1-C2 alkyl group, benzoyl group, acryl group, penyl group, ether group, ester group, keton group, sulfide group, sulfon group, fulfoxide group, or phosphor diester.

Description

High flow rate reverse osmosis membrane and its manufacturing method {REVERSE OSMOSIS MEMBRANE WITH HIGH FLUX AND MANUFACTURING METHOD THEREOF}

The present invention relates to a reverse osmosis membrane and a method for producing the same, and more particularly, to a reverse osmosis membrane comprising a polyfunctional amine compound in the production of a polyamide-based active layer and a method for producing the same.

The osmotic phenomenon is called the osmotic phenomenon, in which the concentration of the two solutions becomes uniform as the solvent moves through the membrane from the low concentration solution to the high solution according to the concentration gradient between the two solutions separated by the semipermeable membrane. The pressure acting on the solution side is called osmotic pressure. However, applying an external pressure higher than the osmotic pressure causes the solvent to reverse to the lower concentration solution. This phenomenon is called reverse osmosis. The reverse osmosis principle uses a pressure gradient as a driving force to separate various salts or organic substances using a semipermeable membrane, which is used to purify water or to concentrate solutes.

Such a reverse osmosis membrane can be classified into a monolithic asymmetric membrane composed of the same material as the salt exclusion layer and the porous support and a composite membrane composed of different materials. The asymmetric membrane has the advantage of being easy to manufacture and inexpensive using the same material, but has a disadvantage of low salt excretion rate and low permeation flow rate, whereas the composite membrane can freely select the material of the active layer according to the use and crosslink the bond with the support. Can be solidified through has the advantage of having more excellent durability.

Representative examples of reverse osmosis membranes include polyamide reverse osmosis membranes, and polyamide reverse osmosis membranes are manufactured by forming a polyamide active layer on a porous support, and more specifically, on a nonwoven fabric A sulfone layer is formed to form a porous support, and the porous support is immersed in an aqueous solution of m-phenylene diamine (mPD) to form an mPD layer, which in turn is trimesoyl chloride (TMC). It is manufactured by the method of forming a polyamide layer by immersing in an organic solvent and making an mPD layer contact with TMC and interfacially polymerizing.

In order for the reverse osmosis membrane to be used commercially, the salt removal rate must be high and the permeate flow rate that can pass a relatively large amount of water even at a relatively low pressure must be excellent. Therefore, there is a demand for the development of a more economical method for producing a reverse osmosis membrane having excellent salt rejection rate and high permeation flux.

The present invention is to provide a reverse osmosis membrane and a manufacturing method having a high salt excretion rate and a high permeate flow rate.

In one aspect, the present invention is a porous support; And a reverse osmosis membrane comprising a polyamide-based active layer formed on the porous support, wherein the polyamide-based active layer provides a reverse osmosis membrane comprising a compound represented by the following [Formula 1].

[Chemical Formula 1]

In this case, R is preferably a C1-C12 alkyl group, benzoyl group, acryl group, phenyl group, ether group, ester group, ketone group, sulfide group, sulfone group, sulfoxide group or phosphodiester.

At this time, the compound represented by [Formula 1] is 1,3,5-tri-4-aminobenzoic benzene, 1,3,5-tri-4-aminotherbenzene and 1,3,5-tri-4 It is preferable that it is at least 1 type selected from the group which consists of -aminoethylbenzene.

In another aspect, the present invention is a step of coating an amine aqueous solution containing the compound represented by the formula [1] on a porous support and contacting an aliphatic hydrocarbon-based organic solution containing an acyl halide on the amine aqueous solution coating layer It provides a method for producing a reverse osmosis membrane comprising a.

At this time, the amine aqueous solution preferably comprises a compound represented by [Formula 1] in an amount of 0.2 to 10% by weight.

The reverse osmosis membrane of the present invention has the same or higher salt rejection rate as the conventional reverse osmosis membrane, but exhibits a higher permeate flow rate than the conventional reverse osmosis membrane.

Hereinafter, the present invention will be described more specifically.

Reverse osmosis membrane of the present invention (1) a porous support; And (2) a polyamide-based active layer formed on the porous support, wherein the polyamide-based active layer preferably includes a compound represented by the following [Formula 1].

[Chemical Formula 1]

In this case, R is preferably a C1-C12 alkyl group, benzoyl group, acryl group, phenyl group, ether group, ester group, ketone group, sulfide group, sulfone group, sulfoxide group or phosphodiester.

As said (1) porous support body, what formed the coating layer of a polymeric material on the porous base material like a nonwoven fabric can be used. The porous substrate is preferably a uniform distribution of pores so that the polyamide-based active layer can be formed well. In addition, as the polymer material, for example, polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetheretherketone, polypropylene, polymethylpentene, polymethyl chloride and polyvinyl Regenfluoride or the like may be used, but is not necessarily limited thereto. Of these, polysulfone is particularly preferable.

Meanwhile, the polyamide-based active layer (2) may be formed by an interfacial polymer of a polyfunctional amine compound and an acyl halide compound, and in this case, it is preferable to use a compound represented by the above [Formula 1] as the polyfunctional amine compound. .

The compound represented by [Formula 1] is prepared by synthesizing 1,3,5-tri (4-nitrobenzoic) benzene using trimesoyl chloride and 1-nitrobenzene and then replacing the nitrogen dioxide group with an amine group can do. In addition, the compound represented by the above [Formula 1] having a functional group of various R can be prepared using a method of replacing the nitrogen dioxide group with an amine group.

At this time, the compound represented by the above [Formula 1] is not limited to this, for example, 1,3,5-tri-4-aminobenzoic benzene, 1,3,5-tri-4-aminotherbenzene And 1,3,5-tri-4-aminoethylbenzene or mixtures thereof. In particular, 1,3,5-tri-4-aminobenzoic benzene is preferable.

In this case, when the compound represented by [Formula 1] is used to form the polyamide-based active layer, the surface containing the long chain may be formed due to the R functional group between the amine and the benzene ring, and thus, the conventional diamine-based compound is formed. A polyamide-based active layer having pores relatively larger than one polymerized surface can be formed. In addition, since the compound contains three amine groups acting as a reactor, and forms a more complex three-dimensional structure than the polymerization surface formed using a conventional diamine-based compound to increase the surface area, the reverse osmosis membrane of the present invention is an excellent salt It has the effect of improving the water permeability while maintaining the rate.

According to the experiments of the present inventors, when using the compound represented by the above [Formula 1] in the preparation of the polyamide-based active layer as described above, at 25 ℃, 800psi, the initial salt excretion rate is 97% or more conventional reverse osmosis While having the same or superior salt rejection rate as the separator, the initial permeate flow rate was 25 to 36 gallon / ft ² · day and was shown to have a higher permeate flow rate than the conventional reverse osmosis membrane.

More specifically, the present invention is a reverse osmosis membrane having an initial salt rejection ratio of 97% or more and an initial permeation rate of 26 to 33 gallon / ft ² · day, particularly at an initial salt rejection ratio of 97% or more, at 25 ° C. and 800 psi. The flow rate may implement a reverse osmosis membrane of 28 to 35 gallon / ft ² · day.

Next, the manufacturing method of the reverse osmosis membrane of this invention is demonstrated.

The reverse osmosis membrane of the present invention comprises the steps of coating an aqueous amine solution containing the compound represented by the above [Compound 1] on a porous support and contacting an aliphatic hydrocarbon-based organic solution containing an acyl halide on the aqueous amine coating layer It can be prepared including the step.

At this time, the method of forming the polyamide active layer on the porous support is not particularly limited, and may be performed by a method for preparing a reverse osmosis membrane well known in the art.

In the above production method, a dip coating, spin coating, spray coating, etc., immersed in an aqueous amine solution well known in the art may be used as a method of coating the aqueous amine solution on a porous support.

The aqueous amine solution preferably includes a compound represented by the above [Formula 1], but is not limited thereto, for example, 1,3,5-tri-4-aminobenzoic benzene, 1,3,5 -Tri-4-aminotherbenzene and 1,3,5-tri-4-aminoethylbenzene or mixtures thereof and the like. In particular, 1,3,5-tri-4-aminobenzoic benzene is preferable.

On the other hand, the amine aqueous solution may contain the compound represented by the above [Formula 1] in an amount of 0.2 to 10% by weight, preferably 0.5 to 8% by weight, particularly preferably 0.8 to 9% by weight. At this time, when added in less than 0.2% by weight, the concentration of the amine adsorbed on the porous support is low, the polyimide active layer is thinly formed, the effect of the salt removal rate is insignificant, when added in excess of 10% by weight, excess amine Adsorbed on the porous support, the polyimide-based active layer is formed thick, and thus the permeation flow rate may be lowered.

Next, forming the polyamide-based active layer on one side of the porous support coated with the amine aqueous solution may be performed by contacting an aliphatic hydrocarbon-based organic solution including an acyl halide with the porous support having the coating layer formed thereon. In this case, the contact may be performed by methods well known in the art, for example, dipping or spraying, but is not necessarily limited thereto.

On the other hand, the aliphatic hydrocarbon-based organic solution is not limited to this, for example, it is preferable that the trimezoyl chloride, isophthaloyl chloride, terephthaloyl chloride or a mixture thereof. The aliphatic hydrocarbon solvent used should not participate in the interfacial polymerization, not with acyl halides and should not affect the initial porous support.

After the porous support on which the polyamide-based active layer is formed, a post-treatment process of drying and washing may be added. At this time, the drying and washing step is not particularly limited, it is possible to apply a process commonly used in the art.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited thereto.

Example  One

18 wt% of polysulfone solids were added to a DMF (N, N-dimethylformamide) solution and dissolved at 80 to 85 ° C. for at least 12 hours to obtain a uniform liquid phase. The solution was cast to a thickness of 45 to 50 μm on a polyester nonwoven fabric having a thickness of 95 to 100 μm, and then a porous polysulfone support was formed.

The porous polysulfone support prepared by the above method was prepared in an amine aqueous solution containing 1% by weight of 1,3,5-tri-4-aminobenzoic benzene (1,3,5-tri (4-aminobenzoic) benzene, TAB). After soaking for 2 minutes, the excess aqueous solution on the support was removed using a compression roller, and dried at room temperature for 1 minute.

Then, the support was immersed for 1 minute in an organic solution of 0.1% by weight of trimezoyl chloride using ISOL-C (SK Chem.) Solvent, then taken out, and dried in an oven at 60 ℃. Then, after washing with 0.2% by weight aqueous sodium carbonate solution at room temperature for 2 hours or more, washed with distilled water to prepare a reverse osmosis membrane.

Example  2

Reverse osmosis membrane was prepared in the same manner as in Example 1 except that the aqueous amine solution contained 2% by weight of TAB.

Example  3

Reverse osmosis membranes were prepared in the same manner as in Example 1, except that 3 wt% TAB was included in the amine aqueous solution.

Example  4

A reverse osmosis membrane was prepared in the same manner as in Example 1 except that 4 wt% of TAB was included in the aqueous amine solution.

Example  5

Reverse osmosis membranes were prepared in the same manner as in Example 1, except that 5 wt% of TAB was included in the amine aqueous solution.

Comparative Example  One

Reverse osmosis membrane was prepared in the same manner as in Example 1 except that the aqueous solution of amine contained 2 wt% of metaphenylenediamine (mPD) instead of TAB.

Experimental Example  1-integer performance evaluation

The initial salt rejection rate and initial permeation flux of the reverse osmosis membranes prepared by Examples 1 to 5 and Comparative Example 1 were measured. The initial salt rejection rate and the initial permeate flow rate were measured while supplying 32,000 ppm aqueous sodium chloride solution at 25 ° C at a flow rate of 4500 mL / min. The reverse osmosis membrane cell device used for the membrane evaluation was a Sepa CF II cell of GE Osmoisis, which was equipped with a flat plate permeation cell, a high pressure pump, a storage tank, and a cooling device. The structure of the flat plate permeation cell was cross-flow type. The effective transmission area is 140 cm ² . After the washed reverse osmosis membrane was installed in the permeation cell, preliminary operation was sufficiently performed for about 1 hour using tertiary distilled water to stabilize the evaluation equipment. Then, the apparatus was operated for about 1 hour until the pressure and permeate flow rate reached a steady state by replacing with 32,000 ppm sodium chloride aqueous solution. Then, the flow rate was calculated by measuring the amount of water permeated for 10 minutes, and the conductivity was measured with a Conductivity Meter ) Was used to calculate the salt rejection rate by analyzing the salt concentration before and after permeation. The measurement results are shown in Table 1 below.

Initial salt exclusion rate (%) Initial permeate flow (gallon / ft ² · day) Example 1 97.0 25.5 Example 2 98.1 31.2 Example 3 98.1 35.8 Example 4 97.9 32.4 Example 5 97.9 28.5 Comparative Example 1 96.8 20.6

Claims (6)

A porous support; And
Reverse osmosis membrane comprising a polyamide-based active layer formed on the porous support,
The polyamide-based active layer is a reverse osmosis membrane comprising a compound represented by the following [Formula 1].
[Chemical Formula 1]

In this case, R is a C1-C12 alkyl group, benzoyl group, acryl group, phenyl group, ether group, ester group, ketone group, sulfide group, sulfone group, sulfoxide group or phosphodiester.
The method of claim 1,
The compound represented by [Formula 1] is 1,3,5-tri-4-aminobenzoic benzene, 1,3,5-tri-4-aminotherbenzene and 1,3,5-tri-4-amino Reverse osmosis membrane is one or more selected from the group consisting of ethylbenzene.
3. The method according to any one of claims 1 to 2,
The reverse osmosis membrane, the reverse osmosis membrane at 25 ℃, 800psi, the initial salt rejection rate is 97% or more, the initial permeation flow rate is 25 to 36 gallon / ft ² · day.
Coating an aqueous amine solution containing a compound represented by the following [Formula 1] on the porous support; And
Method for producing a reverse osmosis membrane comprising the step of contacting an aliphatic hydrocarbon-based organic solution containing an acyl halide on the aqueous amine coating layer.
[Chemical Formula 1]

In this case, R is a C1-C12 alkyl group, benzoyl group, acryl group, phenyl group, ether group, ester group, ketone group, sulfide group, sulfone group, sulfoxide group or phosphodiester.
5. The method of claim 4,
The compound represented by [Formula 1] is 1,3,5-tri-4-aminobenzoic benzene, 1,3,5-tri-4-aminotherbenzene and 1,3,5-tri-4-amino Method for producing a reverse osmosis membrane is one or more selected from the group consisting of ethylbenzene.
5. The method of claim 4,
The amine aqueous solution is a method for producing a reverse osmosis membrane comprising the compound represented by the formula [1] in an amount of 0.2 to 10% by weight.