KR101017896B1 - High chemical resistant RO membrane and method of preparing the same - Google Patents

Abstract

The present invention relates to a method for producing a hollow fiber reverse osmosis membrane, comprising the steps of: a) spinning a hollow fiber; b) after applying the polysulfone solution to the spun hollow fiber, the phase transition while passing through a water bath to produce a porous fiber; c) immersing the porous fiber in an amine aqueous solution containing 2,6-diaminotoluene and then removing it; d) passing the porous fiber through an orifice to remove the amine aqueous solution present in excess on the surface; And e) dipping and removing the porous fiber from which the excess amine aqueous solution is removed in the organic solution of the amine reactive compound including the polyfunctional acyl halide monomer, and then heating to form an active layer; It relates to a method for producing a hollow fiber reverse osmosis membrane having excellent chemical resistance.

Hollow fiber reverse osmosis membrane, orifice, chemical resistance

Description

High chemical resistant RO membrane and method of preparing the same

The present invention relates to a hollow fiber reverse osmosis membrane and a method for manufacturing the same, and more particularly, to a method for manufacturing a hollow fiber reverse osmosis membrane that solves the problem that the conventional hollow fiber reverse osmosis membrane is difficult to manufacture by using a specific device. The present invention also relates to a method for producing a hollow fiber reverse osmosis membrane having excellent chemical resistance by using a specific amine in the preparation of the hollow fiber reverse osmosis membrane.

Generally, it is classified into microfiltration membrane, nanofiltration membrane, ultrafiltration membrane, and reverse osmosis membrane according to the size of membrane separation particles, and divided into spiral wound module, tubular module, hollow fiber module, flat membrane module, and monolithic module according to membrane module. do.

The reverse osmosis membrane has a pore diameter of 0.001 to 0.0001 μm, which means inorganic membranes or low molecular organics, which are separated by osmosis. The reverse osmosis membrane can separate even ionic substances, mainly desalination, pulp waste liquid purification, and plating wastewater treatment. It is used for. In general, the reverse osmosis membrane is composed of a porous support layer and an active layer which is a polyamide-based thin film formed on the porous support layer. The polyamide active layer is formed by interfacial polymerization of a polyfunctional amine and a polyfunctional acyl halide. For interfacial polymerization, after immersion in the polyfunctional amine aqueous solution, the excess aqueous solution is removed, and then immersed in the polyfunctional acyl halide organic solution for interfacial polymerization. In general, the reverse osmosis membrane uses a nonwoven fabric as a support, and since it is a flat membrane type, an extra aqueous solution can be removed using a rubber roller or the like.

Hollow fiber modules are arranged from thousands to tens of thousands of fibrous yarns with voids in the pressure vessel. Compared to other modules, the surface area per volume is the widest, and it is divided into internal pressure type and external pressure type according to the transmission method. Such a hollow fiber module was difficult to remove the excess amine solution after immersion in the polyfunctional amine solution when prepared as a reverse osmosis membrane in its shape. Therefore, although the surface area of the separator per module has a small disadvantage, it cannot be manufactured as a hollow fiber type membrane due to problems in the membrane manufacturing technology.

In addition, the recent study on the chlorine-resistant polyamide reverse osmosis membrane is studying a polyamide structure having a structure that is not reactive with chlorine through the design of a new molecular structure, but a breakthrough membrane that does not react with chlorine has not been developed yet to be.

The conventional reverse osmosis membrane has a disadvantage of having a small membrane surface area per module as a flat membrane type, but is easily manufactured to produce a flat membrane type. Although the hollow fiber membrane has a large membrane surface area per module, it is difficult to remove the excess amine solution present on the fiber surface due to the manufacturing technology, so that the hollow fiber membrane cannot be distributed evenly on the surface and the porous pores. It is not manufactured by.

Therefore, it is an object of the present invention to manufacture a hollow fiber reverse osmosis membrane having excellent water permeability and mechanical strength.

In another aspect, the present invention is to provide a polyamide hollow fiber reverse osmosis membrane and a method for producing the same having excellent chemical resistance without post-treatment or without using an additive in an amine aqueous solution.

In particular, the present invention provides a polyamide hollow fiber reverse osmosis membrane and a method for preparing the same, which have almost no molecular weight change before and after exposure to chlorine, and which exhibit very high chlorine resistance as compared to conventional metaphenylenediamine (MPD).

In the present invention to produce a hollow fiber reverse osmosis membrane having excellent smoothness by removing the excess amine aqueous solution using an orifice tube which is a device designed in the present invention to produce a high permeability hollow fiber reverse osmosis membrane having excellent chemical resistance and excellent mechanical strength. To provide a method.

Specifically, the present invention

a) spinning the hollow fiber fibers;

b) after applying the polysulfone solution to the spun hollow fiber, the phase transition while passing through a water bath to produce a porous fiber;

c) immersing the porous fiber in an amine aqueous solution containing 2,6-diaminotoluene and then removing it;

d) passing the porous fiber through an orifice to remove the amine aqueous solution present in excess on the surface;

e) immersing and removing the porous fiber from which the excess amine aqueous solution has been removed in an organic solution of an amine reactive compound containing a polyfunctional acyl halide monomer, and then heating to form an active layer;

It relates to a method for producing a hollow fiber reverse osmosis membrane having excellent chemical resistance.

In the present invention, the orifice uses a supporter having a hole having a size through which the porous fiber can pass, and a Teflon ring attached to the inside or the top of the hole.

The present invention is characterized by using a method of removing an extra amine aqueous solution using an orifice of the present invention after immersion in an aqueous amine solution without the addition of a separate pretreatment or post-treatment process, and by using such a device, a hollow fiber type reverse osmosis membrane having excellent smoothness The manufacture of was made possible.

In addition, the inventors of the present invention, in the known polyamide reverse osmosis membrane production method, by using a polyfunctional aromatic amine monomer having a methyl group capable of electron donation, other conventional multifunctional aromatic amine monomer (for example, metaphenylenediamine The present invention was completed by discovering that a polyamide reverse osmosis membrane having a very excellent chlorine resistance can be prepared as compared with the case of using the same.

In particular, in the present invention, when 2,6-diaminotoluene is used, other polyfunctional aromatic amine monomers (for example, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,4-diamino The present invention was completed by discovering that a polyamide reverse osmosis membrane having very excellent chlorine resistance as compared with toluene and the like can be produced.

Therefore, the hollow fiber-type reverse osmosis membrane production method of the present invention is characterized by using 2,6-diaminotoluene in the preparation of the amine aqueous solution in the method of preparing a polyamide reverse osmosis membrane by interfacial polymerization of a known amine aqueous solution and an amine reactive compound. By using 6-diaminotoluene, a reverse osmosis membrane having excellent chlorine resistance can be produced without a separate post-treatment step.

Hereinafter, the present invention will be described in more detail.

An orifice used in the present invention is shown in FIG. As shown in FIG. 1, a supporter 10 having a hole 11 having a size through which the porous fiber 30 can pass, and a teflon ring 20 attached to the inside or the top of the hole are used.

At this time, the Teflon ring 20 is to remove the excess amine aqueous solution of the porous fiber 30, evenly present on the surface and pores to increase the smoothness, and to increase the bonding force between the porous fiber and the sulfur layer, chemically inert It is preferable to use a ring made of Teflon as a material having properties such as heat resistance, non-tackiness, and low coefficient of friction.

In the present invention, the heating of step e) is preferably performed for 1 to 5 minutes at 100 to 150 ° C. as a process for interfacial polymerization and drying.

In the present invention, the hollow fiber is selected from polysulfone, polyisulfone, polyimide, polyamide, polyimide, polyacrylonitrile, polymethyl methacrylate, polyethylene, polypropylene, polyvinylidene fluoride Use either.

In the present invention, the polyfunctional acyl halide as the amine reactive compound is selected from one or a mixture of two or more selected from trimesoyl chloride, terephthaloyl chloride, and isophthalolyl chloride. Can be.

In the present invention, the aqueous amine solution may be added to a variety of reagents to facilitate the film forming, and to improve the permeation performance of the resulting reverse osmosis membrane. Specifically, any one or a mixture of two or more selected from a surfactant, triethylamine, and camphorsulfonic acid may be further included. As the surfactant, sodium lauryl sulfate is preferable, and the aqueous amine solution is increased by 1.5 to 2 times the amount used for the flat membrane to increase the wettability to the surface of the porous support and the pores, 0.015 to 2% by weight. It is preferable to use it in the range. Triethylamine and camphorsulfonic acid are used to remove hydrogen halides produced by permeability enhancement and interfacial polymerization, and are preferably used in the range of 0.01 to 5% by weight. If the concentration is not significantly affected and the concentration is exceeded, the interfacial polymerization may be prevented, thereby preventing a proper thin film from being formed. Isopropyl alcohol is used to increase the flow rate of the membrane, it is preferable to use in the range of 1 to 30% by weight, there is a disadvantage that the salt rejection rate of the composite membrane is reduced when the excess alcohol is added, the effect of adding a small amount of alcohol Minor problems can arise.

In the case of the organic solution reacting with the amine aqueous solution, it is preferable to use an organic solvent that does not mix with water, and as such a solvent, a hydrocarbon containing alkanes having 8 to 12 carbon atoms in consideration of environmental problems and fires due to boiling points, etc. Can be preferably used, of which IsolC (SK Chem.) Can be preferably used.

The manufacturing method according to the present invention can produce a hollow fiber reverse osmosis membrane having a smoothness with a simple method.

In addition, by using 2,6-diaminotoluene, it is possible to produce a reverse osmosis membrane having much improved chlorine resistance compared to other polyfunctional aromatic amine monomers commonly used.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

[Production Example 1]

In order to examine the chlorine resistance and chemical stability of the reverse osmosis membrane, 2,6-diaminotoluene (2,6-DAT) and trimezoyl chloride (TMC), the reverse osmosis membrane active layer materials, were interfacially polymerized. To an aqueous 0.01 mol 2,6-diaminotoluene solution was added 0.015 mol trimezoyl chloride (TMC) dichloroethane in the same amount slowly at room temperature. At this time, the reactants were strongly stirred and reacted for a certain time to produce a polyamide active layer material.

The synthesized active layer material was reacted for 48 hours in an aqueous 1% sodium hypochlorite solution, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below. It was.

[Comparative Production Example 1]

A reverse osmosis membrane was prepared in the same manner as in Preparation Example 1, except that metaphenylenediamine (MPD) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

[Comparative Production Example 2]

A reverse osmosis membrane was prepared in the same manner as in Preparation Example 1, except that 2,4-diaminoanisole (2,4-DAA) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1. Prepared.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

[Comparative Production Example 3]

A reverse osmosis membrane was prepared in the same manner as in Preparation Example 1, except that 2,4-diaminotoluene (2,4-DAT) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1. It was.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

[Comparative Production Example 4]

A reverse osmosis membrane was prepared in the same manner as in Preparation Example 1, except that 3,4-diaminotoluene (3,4-DAT) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1. Prepared.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

[Comparative Production Example 5]

Reverse osmosis membrane in the same manner as in Preparation Example 1, except that 4-chloro-1,3-phenylenediamine (4-CMPD) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1 Was prepared.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

[Comparative Production Example 6]

A reverse osmosis membrane was prepared in the same manner as in Preparation Example 1, except that 2,5-diaminotoluene (2,5-DAT) was used instead of 2,6-diaminotoluene (2,6-DAT) in Preparation Example 1. It was.

In addition, a 1% sodium hypochlorite solution was reacted for 48 hours, washed with distilled water, and dried in vacuo to measure molecular weight changes before and after exposure to chlorine using GPC, and the results are shown in Table 1 below.

TABLE 1

In Table 1, the degradation ratio is (Mw _i -Mw _a ) × 100 / Mw _i (%). Mw _i is the weight average molecular weight before treatment, and Mw _a is the weight average molecular weight after treatment.

As shown in Table 1, the 2,6-diaminotoluene (2,6-DAT) of Preparation Example 1 having an amino group at the nearest ortho position of the methyl group has a very low decomposition value compared to other amine monomers. It showed that the chemical stability is the best. This may be because the electron donation of the methyl group affects the stability of the amide bond. Therefore, in the present invention, 2,6-diaminotoluene (2,6-DAT) was selected and used.

Example 1

17 wt% polysulfone was dissolved in n-methylpyrrolidone (NMP) to prepare a coating solution. The prepared coating solution was applied onto a woven tubular polypropylene (PP) support (outer diameter 2.0 mm, inner diameter 1.5 mm) and then a hollow support was prepared by a phase transfer method.

The prepared porous support was 3.0 wt% 2,6-diaminotoluene (2,6-DAT), 3.0 wt% camphorsulfonic acid, 0.3 wt% sodium lauryl sulfate, 3.0 wt% triethylamine, and 5.0 wt% It was immersed for 1 minute in an aqueous solution containing% isopropyl alcohol. After removing the porous support, it was passed through a roller designed in the present invention (Fig. 1) to remove excess surface water. Next, immerse in IsolC (Sk Chem. Corp.) organic solution containing 0.2% by weight of trimezoyl chloride (TMC) and 0.05% by weight of isopropyl alcohol for 10 seconds, take it out, and dry at 120 ° C for 3 minutes to form a hollow fiber reverse osmosis membrane. Prepared.

In order to examine the permeation characteristics of the prepared hollow fiber reverse osmosis membrane was measured using a 2000 ppm NaCl aqueous solution at an operating pressure of 1Mpa, temperature 25 ℃, the results are shown in Table 2.

Also, chemical resistance test of hollow fiber reverse osmosis membrane was conducted. In the method, the prepared reverse osmosis membrane was immersed in a 100 ppm aqueous solution of hypochloride for a predetermined time and then subjected to a permeation test. At this time, the operating pressure was measured using a 2000 ppm NaCl aqueous solution at 1 Mpa, temperature 25 ℃. The results are shown in Table 3 below.

Comparative Example 1

Except for using 2,6-diaminotoluene (2,6-DAT) in place of Example 1 except for using a phenyl phenylamine diamine (MPD) reverse osmosis membrane was prepared in the same manner as in Example 1.

In order to examine the permeation characteristics of the prepared hollow fiber reverse osmosis membrane was measured using a 2000 ppm NaCl aqueous solution at an operating pressure of 1Mpa, temperature 25 ℃, the results are shown in Table 2.

Also, chemical resistance test of hollow fiber reverse osmosis membrane was conducted. In the method, the prepared reverse osmosis membrane was immersed in a 100 ppm aqueous solution of hypochloride for a predetermined time and then subjected to a permeation test. At this time, the operating pressure was measured using a 2000 ppm NaCl aqueous solution at 1 Mpa, temperature 25 ℃. The results are shown in Table 3 below.

TABLE 2

As shown in Table 2, Example 1 according to the present invention was found to have a higher transmission rate than Comparative Example 1, showing an excellent rejection rate.

[Table 3]

As shown in Table 3, in the case of Example 1, even in a long time chemical resistance test, it showed stable chemical resistance characteristics such that there was almost no change in the transmission characteristics. Therefore, the hollow fiber reverse osmosis membrane prepared by the present invention was found to have excellent permeability and chemical resistance as well as an excellent mechanical strength in the form of hollow fiber reinforced with a support.

Figure 1 shows an example of the orifice used to remove the excess amine solution in the present invention.

10: supporter 11: hall

20: Teflon ring 30: porous fiber

Claims (6)

a) spinning the hollow fiber fibers; b) after applying the polysulfone solution to the spun hollow fiber, the phase transition while passing through a water bath to produce a porous fiber; c) immersing the porous fiber in an amine aqueous solution containing 2,6-diaminotoluene and then removing it; d) passing the porous fiber through an orifice to remove the amine aqueous solution present in excess on the surface; e) immersing and removing the porous fiber from which the excess amine aqueous solution has been removed in an organic solution of an amine reactive compound containing a polyfunctional acyl halide monomer, and then heating to form an active layer; Method for producing a hollow fiber reverse osmosis membrane with excellent chemical resistance comprising a. The method of claim 1, The hollow fiber is any one selected from polysulfone, polyisulfone, polyimide, polyamide, polyimide, polyacrylonitrile, polymethyl methacrylate, polyethylene, polypropylene, polyvinylidene fluoride Method for producing hollow fiber reverse osmosis membrane with excellent chemical resistance. 3. The method of claim 2, The polyfunctional acyl halide is a chemical resistant hollow fiber reverse osmosis membrane of any one or two or more selected from trimesoyl chloride, terephthaloyl chloride, isophthalolyl chloride, and isophthalolyl chloride. Manufacturing method. The method of claim 3, wherein The aqueous amine solution is a method of producing a hollow fiber-type reverse osmosis membrane having excellent chemical resistance further comprises any one or a mixture of two or more selected from surfactants, triethylamine, camphorsulfonic acid (camphorsulfonic acid). The method of claim 1, The orifice is a supporter having a hole having a size through which porous fibers can pass, and a method of manufacturing a hollow fiber reverse osmosis membrane having excellent chemical resistance, characterized in that the Teflon ring is attached to the inside or the top of the hole. A hollow fiber reverse osmosis membrane having excellent chemical resistance prepared by the method of any one of claims 1 to 5.

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