KR20120099189A - Reverse osmosis membranes comprising surface-modified nanocarbon material and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A reverse osmosis membrane containing surface reformed nano-carbon materials and a method for manufacturing the same are provided to increase the convenience of operational processes and to enhance the durability of polymer in a reverse osmosis membrane. CONSTITUTION: A reverse osmosis membrane includes an active layer and a supporting layer. Nano-carbon materials, of which surfaces are combined with amine groups, are introduced into the active layer. The supporting layer is based on a porous support. The nano-carbon materials are selected from carbon nano-tubes, graphene, and fullerene. The nano carbon materials are inserted into or applied on the activating layer. The porous support is a polysulfone support. A method for manufacturing the reverse osmosis membrane includes the following: aromatic amine and tertiary amine are dissolved in a polar solvent to obtain a mixed solution; the nano-carbon materials are added into the mixed solution to prepare an immersion solution; the porous support is immersed in the immersion solution to eliminate a remaining solution; the porous support is immersed in an organic solution with dissolved multi-functional acyl halide, and the porous support is dried.

Description

Reverse osmosis membranes comprising surface-modified nanocarbon material and method for manufacturing the same

The present invention relates to a reverse osmosis membrane comprising a surface-modified nanocarbon material and a method for manufacturing the same, and more specifically, to chlorine resistance prepared by introducing surface-modified nanocarbon material into a conventional reverse osmosis membrane active layer manufacturing process through interfacial polymerization. An improved reverse osmosis membrane.

The concept of a conventional reverse osmosis membrane was first presented in the late 1950s, and in 1960, researchers at UCLA invented the first asymmetric reverse osmosis membrane using cellulose acetate. While the reverse osmosis membrane using the cellulose acetate has a low manufacturing cost and a disadvantage of poor performance and durability, efforts have been made to develop the reverse osmosis membrane through other materials.

On the other hand, a composite film is formed by differently forming a material of a thin active layer that removes salt and a thick support layer supporting the same, and an attempt to manufacture such a composite film was first made by Cadotte in 1970. Since then, in 1973, Scala et al. Applied for a reverse osmosis membrane prepared by interfacial polymerization. Since then, reverse osmosis membranes based on aromatic polyamides have been developed. This is the most widely used type of reverse osmosis membrane, which is currently commercialized as consisting of a porous support and a polyamide composite membrane, and an aromatic acyl halide having two or more acyl halide functional groups and an aromatic polyamine containing two amine substituents. It is obtained by interfacial polymerization on a microporous polysulfone support. In particular, it is known that its performance is excellent when metaphenylenediamine (MPDA) dissolved in water is reacted with trimesoyl chloride (TMC) dissolved in Freon (trichlorotriflu oroethane, Freon TF, DuPont).

However, these polyamide reverse osmosis membranes have low chlorine resistance because amide bonds, which are cross-links formed during interfacial polymerization, are extremely vulnerable to chlorine in seawater, resulting in shorter membrane replacement cycles, resulting in lower overall efficiency of seawater desalination. It was. Therefore, the development of reverse osmosis membrane with less performance deterioration even after prolonged exposure to seawater has been continuously demanded, but there is no practical technology due to manufacturing problems.

S. Callcut, J.C. Knowles, Correlation between structure and compressive strength in a reticulated glass-reinforced hydroxyapatite foam, J. Mater. Sci .: Mater. Med. 13 (2002) 485-489. C. J. Bae, H. W. Kim, Y. H. Koh, and H. E. Kim, Hydroxyapatite (HA) Bone Scaffolds with Controlled Macrochannel Pores, J. Mater Sci .: Mater. Med. 17 (2006) 517-521 B. H. Yoon, Y. H. Koh, C. S. Park, and H. E. Kim, Generation of Large Pore Channels for Bone Tissue Engineering using Camphene-based Freeze Casting ", J. Am. Ceram. Soc., 90 (2007) 1744-1752 T.M.G Chu, D.G. Orton, S.J Hollister, S.E. Feinberg, W. Halloran, Mechanical and in vivo performance of hydroxyapatite implants with controlled architectures, Biomaterials 23 (2002) 1283-1293

Accordingly, the present inventors have made a thorough effort to develop a reverse osmosis membrane that can solve the above-described problems in the prior art, and thus have completed the present invention.

After all, it is an object of the present invention to provide a reverse osmosis membrane having improved chlorine resistance prepared by introducing a surface-modified nanocarbon material in the conventional reverse osmosis membrane active layer manufacturing process through interfacial polymerization.

As a means for solving the above problems, the present invention

An active layer into which a nanocarbon material having an amine group bonded to its surface is introduced; And it provides a reverse osmosis membrane comprising a support layer consisting of a porous support.

As another means for solving the above problems, the present invention

Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;

Preparing a supporting solution by adding a nanocarbon material having an amine group bonded to a surface thereof in the mixed solution;

Removing the remaining solution after the porous support is supported on the supported solution; And

Supporting and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved;

It provides a method for producing a reverse osmosis membrane comprising a.

As another means for solving the above problems, the present invention

Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;

Removing the remaining solution after the porous support is supported on the mixed solution;

Treating and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved to form an active layer on the porous support; And

Forming a multi-layered nano-carbon material thin film by repeatedly supporting the nano-carbon material aqueous solution and the nano-carbon material aqueous solution in which an amine group is bonded to the surface of the porous support on which the active layer is formed;

It provides a method for producing a reverse osmosis membrane comprising a.

The reverse osmosis membrane according to an embodiment of the present invention is physically entangled with interfacially polymerized polymers due to the one-dimensional structure of the carbon nanotubes, thereby enhancing the durability of the polymer and exhibiting chemical resistance due to high chemical inertness of the carbon nanotubes The present invention is advantageous in that the process to be added to the existing process is simple and the commercially available carbon nanotubes can be used as it is, which is very convenient for the process.

In addition, the strength of the reverse osmosis membrane active layer is greatly improved due to the introduction of the nano carbon material, and the chemical resistance is also increased due to the additional introduction of the amine group substituted on the surface of the nano carbon material.

1 is a schematic diagram showing the reaction of the reverse osmosis membrane active layer formation according to an embodiment of the present invention.
Figure 2 illustrates a method for producing a reverse osmosis membrane by interfacial polymerization of the MWCNT / MPDA solution and TMC organic solution according to an embodiment of the present invention.
Figure 3 shows the surface modification process of the nano carbon tube and graphene.
It is a schematic diagram of the apparatus used for the performance measurement of a reverse osmosis membrane.
5 is a graph of IR data before the attachment of functional groups and after attachment of functional groups (carboxyl and amine groups).
FIG. 6 is a graph showing changes in flow rate and salt removal rate before and after chlorination of a nanocarbon material-free reverse osmosis membrane.
7 is a graph showing changes in flow rate and salt removal rate before and after chlorination of the reverse osmosis membrane to which 1 wt% of carbon nanotubes are added.
8 is a graph showing changes in flow rate and salt removal rate before and after chlorine treatment of the reverse osmosis membrane to which carbon nanotubes 2.5 wt% are added.
FIG. 9 is a graph showing changes in flow rate and salt removal rate before and after chlorination of a reverse osmosis membrane to which 5 wt% of carbon nanotubes are added.
10 is a graph showing changes in flow rate and salt removal rate before and after chlorination of the reverse osmosis membrane to which 1 wt% of graphene is added.
11 is a graph showing changes in flow rate and salt removal rate before and after chlorination of the reverse osmosis membrane to which 2.5 wt% of graphene is added.
12 is a graph showing changes in flow rate and salt removal rate before and after chlorination of the reverse osmosis membrane to which 5 wt% of graphene is added.
FIG. 13 shows the current-voltage graphs obtained as a result of CV performed on the existing active layer and the aCNT-containing active layer, respectively, before and after chlorine ion exposure.
FIG. 14 shows the current-voltage graphs obtained as a result of CV performed on the existing active layer and the aGO-containing active layer, respectively, before and after chlorine ion exposure.
15 shows a reverse osmosis membrane coated with an active layer of graphene having an amine group bound to its surface according to the present invention.
FIG. 16 is a SEM photograph of a reverse osmosis membrane including a polyamide active layer, an active layer coated with an amine group bonded to an amine group on its surface, and an active layer coated with an graphene 10 layer bonded to an amine group on its surface.
17 is a TEM photograph of a reverse osmosis membrane including an active layer coated with a graphene 10 layer coated with an amine group on a surface thereof.
FIG. 18 is a graph showing changes in flow rate and salt removal rate before chlorination of a reverse osmosis membrane including a polyamide active layer, an active layer coated with 5 layers of PAH / graphene, and an active layer coated with 5 layers of graphene bonded to an amine group on a surface thereof. .
19 is a graph showing changes in flow rate and salt removal rate after chlorination of a reverse osmosis membrane including a polyamide active layer, an active layer coated with 5 layers of PAH / graphene, and an active layer coated with 5 layers of graphene bonded to an amine group on the surface thereof. .
20 is a graph showing current-voltage graphs obtained as a result of CV of a reverse osmosis membrane including an active layer coated with 5 layers of PAH / graphene, before and after exposure to chlorine ions, respectively.
FIG. 21 is a graph illustrating current-voltage graphs obtained as a result of CV of a reverse osmosis membrane including an active layer coated with five graphene layers bonded to an amine group on a surface thereof, before and after exposure to chlorine ions.
FIG. 22 is a schematic diagram illustrating the ion removal process before and after exposure to chlorine ions of the existing polyamide active layer and the polyamide active layer coated with graphene having an amine group bonded to its surface.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description.

It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is an active layer in which a nano carbon material having an amine group bonded to the surface is introduced; And there is provided a reverse osmosis membrane having a support layer made of a porous support.

Since its discovery in 1991, carbon nanotubes have received extraordinary attention from academia due to the combination of strength beyond diamond, extremely large diameter-to-length ratios, and chemically inert properties. The discovery of single-walled carbon nanotubes led to renewed attention to electrical properties, opening the door to device applications. In 1998, Wagner et al. Of the Weizmann Institute of Science reported that polymers containing carbon nanotubes showed significantly improved physical properties compared to general polymers, and research using composite materials of polymers and carbon nanotubes was activated.

Hereinafter, the configuration of the reverse osmosis membrane having an active layer in which a nanocarbon material having an amine group bonded to the surface according to the present invention, and a method of manufacturing the same will be described in more detail.

According to one embodiment of the invention, the active layer is introduced nano-carbon material is coupled to the amine group on the surface; And a reverse osmosis membrane having a support layer made of a porous support may be provided. 1 is a schematic diagram showing a reaction for forming a reverse osmosis membrane active layer. As shown in FIG. 1, the active layer has a structure in which a nanocarbon material substituted with an amine group on its surface is combined with an aromatic amine and a polyfunctional acyl halide. Due to the introduction of the nano carbon material, the strength of the reverse osmosis membrane active layer may be greatly improved, and chemical resistance may also be increased due to the additional introduction of the substituted amine group on the surface of the nano carbon material.

According to another embodiment of the present invention, an active layer coated with a nanocarbon material bonded to the amine group on the surface; And a reverse osmosis membrane having a support layer made of a porous support may be provided.

22 is a schematic representation of the difference in chemical durability due to graphene application through the ion removal mechanism. As can be seen in Figure 22, the application of the graphene layer can be improved by the additional introduction of the ion removal layer unaffected by chlorine ion exposure to improve the salt removal rate after chlorine ion exposure, resulting in improved chlorine resistance.

The nanocarbon material is not particularly limited and may be widely applied, but according to an embodiment of the present invention, it may be selected from the group consisting of carbon nanotubes, graphene, and fullerenes.

According to one embodiment of the invention, the carbon nanotubes may in particular be multi-walled carbon nanotubes. Multi-walled carbon nanotubes can be easily mass-produced to reduce costs compared to the use of single-walled carbon nanotubes, and physical properties are better than single-walled carbon nanotubes, so it is preferable to use multi-walled carbon nanotubes.

In addition, the porous support is not limited as long as it is a support used for a general reverse osmosis membrane, but in one embodiment of the present invention, a polysulfone support may be used.

In addition, according to one embodiment of the present invention, the porous support may be a polysulfone ultrafiltration membrane having pores of 0.001 to 0.01 μm. This is because when the pore size is less than 0.001 μm, the permeate flow rate decreases, and when the pore size is more than 0.01 μm, it is difficult to form the strength for supporting the active layer.

According to another aspect of the invention, dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;

Preparing a supporting solution by adding a nanocarbon material having an amine group bonded to a surface thereof in the mixed solution;

Removing the remaining solution after the porous support is supported on the supported solution; And

Supporting and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved;

It can be provided a method for producing a reverse osmosis membrane comprising a.

Figure 2 illustrates a method for producing a reverse osmosis membrane by interfacial polymerization of the MWCNT / MPDA solution and TMC organic solution according to an embodiment of the present invention.

The present invention includes preparing a solution by dissolving an aromatic amine and a tertiary amine in a polar solvent. The aromatic amine is not particularly limited, but any one selected from the group consisting of m-phenylenediamine (MPDA), o-phenylenediamine (OPDA) and p-phenylenediamine (PPDA) can be used. In addition, the tertiary amine is an acid acceptor for neutralizing hydrochloric acid generated during polymerization, and may be preferably triethylamine (99.5%).

An amine group is bonded to the surface, and the nano carbon material is prepared by treating the nano carbon material with a strong acid and adding an aliphatic diamine to bind an amine group to the surface of the nano carbon material. First, the nanocarbon material is treated with a strong acid to form a carboxyl group on the surface, and then aliphatic diamine is added to bind amine end groups by peptide bonds. Figure 3 shows the surface modification process of these nano carbon tubes and graphene.

The nanocarbon material is not particularly limited and may be widely applied, but according to an embodiment of the present invention, it may be selected from the group consisting of carbon nanotubes, graphene, and fullerenes. In addition, the carbon nanotubes are not particularly limited, but it is preferable to use multi-walled carbon nanotubes (MWCNTs) having an average diameter of 9 to 12 nm and an average length of 10 to 15 μm. The carbon nanotubes interact with the carboxyl groups of the altered multi-walled carbon nanotubes in the polymer matrix of the reverse osmosis membrane and the amide groups generated during interfacial polymerization, thereby making the reverse osmosis membrane more stable from chlorine.

According to one embodiment of the invention, the supporting treatment of the support solution and / or the organic solution of the support may be performed for 1 to 10 minutes.

On the other hand, when the residual solution is not removed, the residual solution must be removed because the interfacial polymerization layer is not formed safely on the supporting film and forms a non-uniform layer after the interfacial polymerization. Removal of the residual solution may be carried out using a sponge, air knife, nitrogen gas blowing, natural drying, or a compression roll, but is not particularly limited.

Thereafter, a polyfunctional acyl halide is dissolved in an organic solvent to prepare an organic solution.

As a solvent of the organic solution, hexane, cyclohexane, heptane, alkanes, etc. which are insoluble in water may be used. In particular, in one embodiment of the invention n-hexane (98%) organic solvent is preferred.

In addition, the polyfunctional acyl halide usable in the present invention may be at least one selected from the group consisting of trimezoyl chloride (TMC), isophthaloyl chloride (IPC) and tetraphthaloyl chloride (TPC).

According to the present invention, a step of performing an interfacial polymerization reaction by finally carrying out the support on which the residual solution is removed is carried out in the organic solution, followed by drying. This drying is to evaporate the remaining organic solvent, the drying step is preferably heat treatment for 1 to 10 minutes at 60 ℃ to 80 ℃.

In addition, the aromatic amine in the aqueous solution is preferably 1 to 20 parts by weight based on 1 part by weight of the polar solvent, the tertiary amine is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the polar solvent. If too little aromatic amine or tertiary amine is used, the salt removal rate is insufficient due to the too thin active layer, and if used excessively, the permeate flow rate is insufficient due to the too thick active layer. In addition, the nano-carbon material having an amine group bonded to the surface is preferably added in an amount of 1 to 10 wt% (0.1 to 10 parts by weight based on 100 parts by weight of aromatic amine) based on the weight of the aromatic amine. This is because there is a problem that a significant increase in chlorine resistance does not appear when less than 1 wt%, and when more than 10 wt% inhibits the formation of a densely-crosslinked amide network during interfacial polymerization.

According to one embodiment of the present invention, the polyfunctional acyl halide may be added in an amount of 0.05 to 5 parts by volume based on 100 parts by volume of the solvent of the organic solution. In this case, the salt removal rate is insufficient due to the too thin active layer at less than 0.05 parts by volume, and the transmission flow rate is insufficient due to the too thick active layer at more than 5 parts by volume.

The present invention also provides

Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;

Removing the remaining solution after the porous support is supported on the mixed solution;

Treating and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved to form an active layer on the porous support; And

Forming a multi-layered nano-carbon material thin film by repeatedly supporting the nano-carbon material aqueous solution and the nano-carbon material aqueous solution in which an amine group is bonded to the surface of the porous support on which the active layer is formed;

It provides a method for producing a reverse osmosis membrane comprising a.

The reverse osmosis membrane manufacturing method is the same as the reverse osmosis membrane manufacturing method described above except that the nano-carbon material is applied to the active layer, wherein the application of the nano-carbon material is anionic nano carbon material and cationic aminated nano-carbon material Is introduced on the previously prepared reverse osmosis membrane active layer through a multilayer thin film self-assembly method using electrostatic attraction.

Specifically, the selected material is immersed in an aqueous solution of cationic aminated nanocarbon material, and the selected material is adsorbed on the surface and washed to leave only the remaining material due to strong attraction force on the surface. It is then immersed in an anionic nanocarbon material oxide aqueous solution and adsorbed onto the surface of the cationic material. It is washed again to form a thin film made of cationic nanocarbon material and anionic nanocarbon material, and this process is repeated to adjust the desired thickness. The reverse osmosis membrane adsorbed by the multilayer thin film prepared through this has the advantage of showing excellent chemical durability in terms of salt removal rate compared to the general reverse osmosis membrane.

In this case, it is preferable to use 1 to 10 wt% (1 to 10 parts by weight based on 100 parts by weight of aromatic amine) based on the weight of the aromatic amine as the aminated nanocarbon material to be applied. If less than 1 wt%, the concentration is low, there is a problem that the lamination is not correct, if more than 10 wt% there is a problem that a uniform solution is not formed due to excessive material content.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that these examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention.

Example  One: Nano Carbon  Attachment of surface functional groups of matter

Carbon nanotubes were made of multi-wall CNT (Hanhwa Nanotech CM-100) as a raw material. To add the functional group, first, 2 g of CNT was added to 200 ml of a mixture of sulfuric acid and nitric acid in a volume ratio of 3: 1, and stirred for 24 hours at 70 degrees to oxidize the surface of the CNT. After the reaction was diluted with a large amount of distilled water, and then recovered by filtration again and dried to obtain a MWCNT attached to the carboxyl group on the surface. The MWCNT thus obtained is subjected to amine substitution again, which adds ethylene diamine to the carboxylated CNT prepared above and adds N, N'-Dicyclohexylcarbodiimide (DCC) as a coupling agent to cause a coupling reaction between the amine and the carboxyl group. It was done by the method. The mixture was reacted at room temperature for 24 hours, and then diluted, filtered, and dried in the same manner as the carboxylated CNT to obtain a dried aminated CNT sample.

In addition, functionalized graphene was prepared by the following process.

First, graphite powder (particle size <0.2mm, Aldrich) was prepared and then oxidized using the brodie method. In other words, 20 g of fuming nitric acid (> 90%, aldrich) and 8.5 g of potassium chlorate (Aldrich) were added together to 1 g of graphite, followed by stirring for 24 hours. Then, the mixture was diluted with a large amount of distilled water and recovered graphene oxide through filtration and drying.

Ethylene diamine was added to the graphene oxide obtained above to synthesize the aminated graphene oxide, which was reacted at room temperature on a mixed solution of ethanol and distilled water. Then, as before, dilute and filtered to obtain an aminated graphene oxide dried.

The functionalized nanocarbons thus formed were subjected to FT-IR analysis to confirm the attachment of functional groups. Were both kinds of the nanocarbon each pristine, oxidated, aminated measurement, the sample produced a KBr pellet was prepared in the form of a powder was measured by using a wavelength range of from 4000cm ^-1 400cm ^-1.

The functional groups were attached to the carbon nanotubes and the graphite powder through chemical treatment, and the attachment of these functional groups was confirmed through FT-IR. The IR data graphs before the functional group attachment and after the functional group attachment (carboxyl group and amine group) are shown in FIG. 5. In the case of carbon nanotubes, no special peak is revealed in the raw material without the functional group, whereas in the carbon nanotube sample after the carboxyl group is attached, a clear carboxyl characteristic peak (-COOH) is observed around 1700 cm ^{-1 and} 1600 cm. A peak of C = O double bond was observed around ^-1 , confirming that a functional group was formed in this sample. In the case of a sample attached an amino group attached to a carboxyl group before the sample confirmed in the C = O double bond as well as the peak 1100cm ^-1 strong -NH ₂ functional group peak, 1650cm ^-1 vicinity of the CO-NH group of a functional group such as a peak is observed in the vicinity of It was confirmed that the diamine is bonded to the carboxyl group attached carbon nanotube sample through an amide bond to have an amine functional group.

The identification of these functional groups was performed in the same way for the graphene powder to which the functional groups were attached. As a result, the characteristic peak of the ether functional group was observed in the oxidized graphene around 1100 cm ^-1 . 1700cm ^-1 was also the front and rear of the carboxyl groups characteristic peak, 3500cm ^-1 vicinity hydroxyl group peak of such observation, the formation of oxidized graphene was confirmed through these functional groups. Amine is a sample is 3000cm ^-1 peak wavelength of such a primary amine group of 3400cm ^-1 peak wavelength and a secondary amine group attached observed in groups was confirmed that the functional groups have successfully as in the case of carbon nanotubes attached.

Example  2: Polyamide Of Nano Carbon  Preparation of Composite Reverse Osmosis Membrane Active Layer

Two different types of active layers including carbon nanotubes and graphene were prepared on a polysulfone-based support membrane. The support membrane was a commercial product model name UE50 of TriSep Co., Ltd., and an ultrafiltration membrane was coated on a surface of a 150 μm-thick polyester nonwoven fabric having a 50 μm-thick asymmetric pore polysulfone. Optimized filtration membranes for spiral-wound modules, capable of withstanding pressures up to 41 bar. M-phenylene diamine (MPDA,> 99%, SigmaAldrich) and Triethylamine (TEA,> 99.5%, Aldrich) and trimesoyl chloride (TMC, 98%, SigmaAldrich) were used to prepare the polyamide-based active layer.

The surface-substituted MWCNT and graphene previously made were used in addition to the polyamide active layer polymerization. First, make a solution by mixing 2 g of m-phenylenediamine (MPDA) and 1.4 ml of Triethylamine (TEA) in 200 ml of distilled water, and add 1 to 5 wt% of MPDA by weight (1 to 5 parts by weight based on 100 parts by weight of MPDA). MWCNT or graphene was dispersed through about 30 minutes of sonication to prepare solution (1). Then, solution (2) was prepared by adding 0.13 ml of Trimesoyl chloride (TMC) to 200 ml of cyclohexane. The surface treated UF membrane was immersed in the solution (1) for about 3 minutes to adsorb the solution (1) on the surface and then taken out to remove the remaining solution on the surface through a roll milling machine (manufactured by Samwon Engineering). Then, it was immersed in the solution (2) again for 3 minutes to cause interfacial polymerization at the membrane surface to form an active layer, and then the membrane sample taken out of the solution was dried at 60 ° C. for 10 minutes to evaporate the remaining solvent. The membrane made through this process was activated in 30 minutes of distilled water before measurement, and then measured.

In the same manner, a reverse osmosis membrane including PAH was also prepared, and the weight of the added PAH was adjusted to 1 to 10 wt% (1 to 10 parts by weight based on 100 parts by weight of MPDA) based on the weight of MPDA.

Example  3: Polyamide  On the active layer Graphene layer  Manufacture of composite reverse osmosis membrane

An active layer of polyamide was prepared on a polysulfone based support layer. The support layer was purchased from TriSep, Inc., an ultrafiltration flat membrane coated with a 50 μm thick asymmetric pore polysulfone on a 150 μm thick polyester nonwoven surface. Materials of m-phenylene diamine (MPDA,> 99%, SigmaAldrich), Triethylamine (TEA,> 99.5%, Aldrich) and trimesoyl chloride (TMC, 98%, SigmaAldrich) were used as raw materials for the polyamide active layer.

When the active layer is polymerized, two solutions are used. First, Solution 1 was prepared by mixing 2 g of m-phenylenediamine (MPDA) and 1.4 ml of Triethylamine (TEA) in 200 ml of distilled water. And solution 2 was prepared by adding 0.13 ml of Trimesoyl chloride (TMC) to 200 ml of cyclohexane. The support layer membrane was sonicated to wash the residue on the surface and then immersed in solution 1 for 3 minutes to adsorb MPDA onto the membrane surface. It was then taken out and the remaining solution on the surface was removed via a roll milling machine (Samwon Engineering). After removal, the MPDA-adsorbed flat membrane was immersed in Solution 2 again for 3 minutes to cause interfacial polymerization of MPDA and TMC on the surface of the support layer to form an active layer. The solution was then removed from the solution and dried in an oven at 60 ° C. for 10 minutes to evaporate cyclohexane.

On the polyamide active layer manufactured through the above process, an active layer using graphene having a functional group attached thereto was further laminated. Graphene with functional groups is prepared by chemical treatment of graphite powder, which is carried out through the following process.

Graphite powder (synthetic, Aldrich), Nitric acid (fuming,> 95%, Junsei), Potassium chlorate (99%, Aldrich), Ethylenediamine (> 98%, Aldrich), Ethanol (Baker) were used. 17 g of potassium chlorate and 40 ml of nitric acid were mixed with 2 g of graphite and stirred for at least 12 hours. Then, the mixture was diluted in distilled water of 5 L or more, and filtration was repeated to make graphene oxide. 1 g of the graphene oxide thus obtained was mixed with 8 ml of Ethylenediamine and 50 ml of ethanol, and reacted by stirring for 12 hours. In the same manner as above, the aminated graphene oxide (AGO) having an amine group bonded to the surface was obtained through distilled water dilution and filter purification.

The prepared graphene was dispersed in distilled water at room temperature at 1 mg / 1ml, respectively, to prepare an aqueous solution of graphite oxide and an aqueous solution of aminated graphene oxide. Then, the graphite oxide solution was prepared by titrating pH 3 and aminated graphene oxide solution to pH 8. Pure distilled water was also prepared by titrating to pH 3 and 8, respectively.

The membrane including the polyamide active layer is first immersed in an aqueous solution of aminated graphene oxide for 10 minutes to attach the graphene oxide layer on which the amination is bonded. Then, the resultant was washed with distilled water at pH 8 to remove the residue on the surface, and the graphite oxide layer was laminated by supporting the aqueous solution of graphite oxide at pH 3. Then, it is washed with distilled water at pH 3 to form a single layer of graphene oxide and graphene oxide combined with amination, and this process is repeated 5 or 10 times to form a 5- or 10-layer thin film composed of graphene and aromatic amines. 5 to 10 wt% of graphene was fixed on the polyamide active layer by weight.

16 and 17 it can be confirmed that the graphene layer is applied to the polyamide active layer.

Experimental Example  One: Polyamide Of Nano Carbon  Composite Reverse Osmosis Membrane Performance Measurement

The performance of the reverse osmosis membrane prepared in Example 2 was measured. For performance measurement, 2,000 ppm brine made by dissolving sodium chloride (NaCl, Aldrich) in ultrapure water was used, and 6,000 ppm made by diluting sodium hypochlorite (NaOCl,> 4%, Sigma-Aldrich) in ultrapure water for chlorine resistance measurement. An aqueous solution of was used.

The apparatus used for measuring the performance of the reverse osmosis membrane was manufactured and tested by constructing a test cell, a brine storage tank, a high pressure pump, an electronic balance, and the like, and the installation structure of the entire apparatus is shown in FIG. 4. The brine from the brine storage tank was fed to the test cell via a pump, and the brine was penetrated and the remaining brine returned to the tank. The test cell is made of stainless steel for the purpose of preventing corrosion by salt water, and the effective penetration area is 13.85 cm ² . The structure of the test cell adopts the Cross-flow Filtration Method, which prevents the deposition of foreign substances in the membrane by flowing salt water parallel to the permeable membrane. . The change in flow rate was calculated by measuring the mass of the produced water at a predetermined time through the electronic balance and calculated based on this result.The salt removal rate was measured using the salinometer (EUTECH PC650) and the concentration of the brine flowing into the membrane. Each measured and compared and calculated. The pressure during the experiment was fixed at 15.5 bar (225 psi) and run under control to remain constant.

When the polyamide-based reverse osmosis membrane was prepared, a reverse osmosis membrane was prepared by adding a nanocarbon material in an amount corresponding to 1 to 5% by weight of MPDA, one of the polyamide-forming monomers, and the performance was measured through a performance measuring device manufactured by the present invention. The measurement was performed by measuring the flow rate and concentration of the produced water by flowing 2,000 ppm brine at a pressure of 15.5 bar to measure the flow rate and concentration of the produced water. The salt removal rate performance of% and the flow rate of 12.5 L / m ² was confirmed.

The membrane to which the carbon nanotubes with the amine group were added was repeatedly tested by selecting three kinds of 1 wt%, 2.5 wt%, and 5 wt%, respectively, based on the amount of the additive, thereby obtaining average performance measurements. As a result, the reverse osmosis membrane containing 1 wt% of amine-based carbon nanotubes showed a slightly lower salt removal rate and flow rate performance of 10.1 L / m ² compared to the non-added comparative membrane. This deterioration intensifies with increasing carbon nanotube content, resulting in a salt removal rate of 90.2% and a flow rate of 13.5 L / m ^{2 for} the carbon nanotube 2.5 wt% membrane and 83.9% for the 5 wt% carbon nanotube membrane. The removal rate and the flow rate of 12.8 L / m ² showed the tendency of performance deterioration with the increase of carbon nanotube content.

The same additive concentration and performance measurement test was performed on the graphene-added film with amine group, and similar stepwise performance deterioration was observed. In the graphene 1 wt% membrane, the flow rate of 12.1 L / m ² and the salt removal rate of 95.1%, and the graphene 2.5 wt% and 5 wt% of the flow rate 13.5 L / m ² , the salt removal rate of 90.2% and the flow rate of 12.7 L / m ² , 88.7% salt removal rate was confirmed. This series of results suggests that the additive introduction itself causes some inevitable impediments to the performance of the reverse osmosis membrane, which is thought to be due to the morphology change of the reverse osmosis membrane due to the additive.

The chlorine resistance performance measurement of the prepared reverse osmosis membrane was carried out for 1 hour in 6,000 ppm NaOCl solution for each membrane sample for measuring the flow rate and salt removal rate performance. This was done by measuring and comparing the performance before and after loading. A reverse osmosis membrane, nano-carbon non-added control group was set to change considerably as a result the flow rate 12.5 L / m ^2, which was 95.1% salt rejection, respectively, the existing Performance Flow 42.5 L / m ^2, 49.1% salt rejection of the test. Both the increased flow rate and the reduced salt removal rate revealed evidence of the loss of the membrane surface active layer, thus confirming the weak chlorine resistance of the general polyamide-based reverse osmosis membrane.

In addition, it was confirmed that the chlorine resistance was significantly improved over both the carbon nanotube-containing film and the graphene-containing film compared to the control group. In the reverse osmosis membrane samples with carbon nanotubes, the salt removal rate decreased from 95.1% to 76.4%, 90.2% to 78.7%, and 83.9% to 80.0% when the concentration was increased to 1, 2.5, and 5 wt%, respectively. 15.1%, 11.5%, and 3.9%, respectively, show that the decrease decreases with increasing concentrations of additives. With the same effect, the flow rate decreases with increasing additive concentration, which increases the flow rate 35.7 L / m ² at 1 wt%, increases the flow rate 26.9 L / m ² at 2.5 wt%, and increases the flow rate 23.0 L / m ² at 5 wt%. Appeared respectively. This is compared with the nanocarbon-free membrane presented as a control, which showed a flow rate of 42.5 L / m ² and a salt removal rate of 49.1% after the measurement of chlorine resistance, showing a 30.0 L / m ² increase and a 46.0% reduction, respectively, compared to the values before the measurement. This is a notable effect. The above results can be seen from FIGS. 6, 7, 8 and 9.

In addition, graphene-containing reverse osmosis membrane samples also showed a noticeable increase in chlorine resistance, which can be confirmed through FIGS. 10, 11, and 12. For reverse osmosis membrane samples containing 1 wt% of graphene by weight of MPDA, the performance of 12.1 L / m ² and salt removal rate 91.7% before chlorine resistance measurement was 43.5 L / m ² and salt removal rate 74.4% after measurement. In particular, 17.3% change in salt removal rate was less than 40% of 46.0% change in the control group, showing a significant increase in chlorine resistance. The increase in chlorine resistance with increasing additives was observed not only in the above carbon nanotubes, but also in the same manner, which was observed for the salt removal rate performance before and after the chlorine resistance measurement of graphene 2.5 wt% reverse osmosis membrane and 5 wt% reverse osmosis membrane, respectively. This is illustrated by a 6% decrease from 91.2% to 87.8% and a 3% decrease from 88.7% to 82.3%.

The results of measuring the performance of the reverse osmosis membrane prepared in Example 3 are shown in FIGS. 18 and 19.

The chlorine resistance performance measurement of the prepared reverse osmosis membrane was carried out for 1 hour in 6,000 ppm NaOCl solution for each membrane sample for measuring the flow rate and the salt removal rate performance. In a self-contained test equipment, a 2,000 ppm NaCl aqueous solution was applied at a pressure of 15.5 bar to re-measure its flow rate and concentration and compare it with the performance before loading. As a control, the nanocarbon uncoated reverse osmosis membrane, which had a flow rate of 13 L / m ² and a salt removal rate of 96%, was changed to a flow rate of 44 L / m ² and a salt removal rate of 47%, respectively. Also, the control group [PAH (poly (arylylamine hydrochloride) as a cationic material), graphene oxide as an anionic material and a reverse osmosis membrane in which a 5-layer thin film was formed by self-assembly method] was 12 L / m. ² , the performance of 93% salt removal rate was changed to 42 L / m ² flow rate, 79% salt removal rate, respectively. On the other hand, the aminated graphene oxide coating of Example 2 (about 5 wt% by weight of aromatic amine) reverse osmosis membrane had a flow rate of 16 L / m ² and a 92% salt removal rate as a result of this test, respectively. ² , the salt removal rate was changed to 86%. That is, it can be confirmed that the reduction rate was significantly reduced by about 6% before and after the chlorine resistance measurement.

Experimental Example  2: Cyclic voltammetry  Measure

Cyclic voltammetry of the reverse osmosis membrane prepared in Example 2 was measured.

For cyclic voltammetry measurements, active layer polymers were formed on Cr and Au-coated Si substrates in a similar manner as in film preparation. The substrate is first cathodic through ozone plasma treatment and the MPDA / TEA / additives (MWCNT, graphene, PAH. Additive concentration fixed at 1 wt% by weight of MPDA) is dropped onto it and coated with a spin coater. It was. The TEA / cyclohexane solution was then dropped on to allow interfacial polymerization to occur and the remaining solution was washed using a spin coater. The sample thus made was dried after drying for 10 minutes at 60 ° C in the same manner as the membrane sample. For each type of additive, a portion of the sample was exposed to chlorine ions at the same concentration as the chlorine resistance test to damage the active layer polymer, and these samples were tested using a cyclic voltammetry measuring instrument to obtain a current-voltage graph. And through this, the degree of damage of the active layer by chlorine ions according to each additive was compared with each other.

It was found that chlorine resistance was improved in the cyclic voltammtry (CV), which was performed to confirm the damage of the active layer polymer due to the chlorine ion attack. 13 and 14 show the current-voltage graphs obtained as a result of CV performed on the existing active layer, the aCNT-containing active layer, and the aGO-containing active layer, respectively, before and after chlorine ion exposure.

The normal active layer without additives showed a noticeable change in the current peak after chlorine exposure. In general, since polyamide is not current, it does not show a large change in current due to voltage change. This damage caused the electrodes underneath to be exposed to show this current flow. On the other hand, other sample electrodes including additives were found to be markedly weakened, which is evidence that the active layer polymers containing additives are more resistant to attack of chlorine ions than the general reverse osmosis membrane active layer polymers. Therefore, it was confirmed that the relatively excellent chlorine resistance of the reverse osmosis membrane active layer containing nanocarbon.

Cyclic voltammetry of the reverse osmosis membrane prepared in Example 3 is shown in Figures 20 and 21, the control group [PAH (poly (arylylamine hydrochloride) as a cationic material), graphene oxide as an anionic material It can be seen that the chlorine resistance is superior to the reverse osmosis membrane in which the 5-layer thin film is formed by the self-assembly method.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do.

It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (12)

An active layer into which a nanocarbon material having an amine group bonded to its surface is introduced; And
Reverse osmosis membrane comprising a support layer made of a porous support.
The method of claim 1,
The nanocarbon material is a reverse osmosis membrane, characterized in that selected from the group consisting of carbon nanotubes, graphene, and fullerenes.
The method of claim 1,
Reverse osmosis membrane comprising an active layer is inserted or coated with a nano-carbon material bonded to the amine group on the surface.
The method of claim 1,
The porous support is a reverse osmosis membrane, characterized in that the polysulfone support.
The method of claim 1,
The porous support is a reverse osmosis membrane, characterized in that the polysulfone ultrafiltration membrane having a pore of 0.001 to 0.01 ㎛.
Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;
Preparing a supporting solution by adding a nanocarbon material having an amine group bonded to a surface thereof in the mixed solution;
Removing the remaining solution after the porous support is supported on the supported solution; And
Supporting and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved;
Method for producing a reverse osmosis membrane comprising a.
Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;
Removing the remaining solution after the porous support is supported on the mixed solution;
Treating and drying the porous support from which the residual solution is removed in an organic solution in which polyfunctional acyl halide is dissolved to form an active layer on the porous support; And
Forming a multi-layered nano-carbon material thin film by repeatedly supporting the nano-carbon material aqueous solution and the nano-carbon material aqueous solution in which an amine group is bonded to the surface of the porous support on which the active layer is formed;
Method for producing a reverse osmosis membrane comprising a.
The method according to claim 6 or 7,
The nano-carbon material having an amine group bonded to the surface is prepared by treating the nano-carbon material with a strong acid and adding an aliphatic diamine to replace the amine group on the surface of the nano-carbon material.
The method according to claim 6 or 7,
The supporting method of the supporting solution or the organic solution of the support is a method for producing a reverse osmosis membrane, characterized in that performed for 1 to 10 minutes.
The method according to claim 6 or 7,
The removal of the residual solution is a method for producing a reverse osmosis membrane, characterized in that using any one selected from the group consisting of sponge, air knife, nitrogen gas blowing, natural drying, and compression roll.
The method according to claim 6 or 7,
The drying step is a method for producing a reverse osmosis membrane, characterized in that the heat treatment for 60 minutes to 80 ℃ for 1 minute to 10 minutes.
The method according to claim 6 or 7,
The nano-carbon material bonded to the amine group on the surface is a method for producing a reverse osmosis membrane, characterized in that added to 1 to 10 wt% based on the weight of the aromatic amine.

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