KR101399827B1 - Method for manufacturing reverse osmosis membranes comprising surface-modified nanocarbon material - Google Patents

Abstract

The present invention relates to a reverse osmosis membrane having improved chlorine resistance, which is prepared by introducing a surface modified nano carbon material into a reverse osmosis membrane active layer production process through interfacial polymerization. In the present invention, an active layer having a nanocarbon material substituted with an amine group on its surface is inserted; And a support layer composed of a porous support.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing a reverse osmosis membrane including a surface-modified nanocarbon material,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse osmosis membrane containing a surface-modified nano carbon material and a method of manufacturing the same, and more particularly, to a reverse osmosis membrane produced by introducing a surface- To an improved reverse osmosis membrane.

The concept of conventional reverse osmosis membranes was first presented at the end of the 1950s, and in 1960, UCLA researchers invented the first asymmetric reverse osmosis membrane using cellulose acetate. Since the reverse osmosis membrane using such acetic acid cellulose has a disadvantage of low production cost but low performance and durability, efforts have been made to develop a reverse osmosis membrane through other materials.

On the other hand, a composite membrane is formed by differently forming a thin active layer for removing the salt and a thick support layer for supporting the same. An attempt to manufacture such a composite membrane was first made by Cadotte in 1970. In 1973, Scala et al. Patented a reverse osmosis membrane prepared by interfacial polymerization. Thereafter, a reverse osmosis membrane based on an aromatic polyamide was developed. It is currently the most widely used reverse osmosis membrane type. It is composed of a porous support and a polyamide composite membrane. Currently, it is commercialized. It is an aromatic polyamine containing two amine substituents and an aromatic acyl halide having three or more acyl halide functional groups. Lt; RTI ID = 0.0 > microporous < / RTI > polysulfone support. Particularly, it has been known that metaphenylenediamine (MPDA) dissolved in water is reacted with trimethoyl chloride (TMC) which is dissolved in freon (Freon TF, DuPont).

However, such polyamide reverse osmosis membranes have a problem that since the amide bond, which is a crosslinking bond formed during the interfacial polymerization, is very weak to chlorine in the seawater and thus exhibits a low chlorine resistance, the membrane replacement cycle is shortened and the efficiency of the entire seawater desalination process is lowered Respectively. Therefore, the development of a reverse osmosis membrane having a small deterioration in performance even after prolonged exposure to sea water has been continuously demanded, but there has been no practical technique 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 intensive efforts to develop a reverse osmosis membrane capable of solving the problems of the prior art described above, and as a result, they have completed the present invention.

It is an object of the present invention to provide a reverse osmosis membrane improved in chlorine resistance, which is produced by introducing a surface modified nano carbon material into a reverse osmosis membrane active layer manufacturing process through interfacial polymerization.

As means for solving the above problems,

An active layer into which a nanocarbon material having an amine group bonded to its surface is introduced; And a support layer composed of a porous support.

As another means for solving the above problems,

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

Adding a nanocarbon material having an amine group to the surface of the mixed solution to prepare a supported solution;

Supporting the porous support on the support solution, and removing the remaining solution; And

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

The present invention also provides a method for producing a reverse osmosis membrane.

As another means for solving the above problems,

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

Supporting the porous support on the mixed solution, and removing the remaining solution;

Supporting the porous support from which the residual solution has been removed in an organic solution in which the polyfunctional acyl halide is dissolved, and drying and forming an active layer on the porous support; And

Forming a nano carbon material multilayer thin film by alternately and repeatedly carrying an aqueous solution of a nano carbon material and an aqueous solution of a nano carbon material having an amine group bonded to the surface of the porous support on which the active layer is formed;

The present invention also provides a method for producing a reverse osmosis membrane.

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 introduction of the substituted amine group on the surface of the nano carbon material.

1 is a schematic view showing a reverse osmosis membrane active layer formation reaction according to an embodiment of the present invention.
FIG. 2 illustrates a method of preparing a reverse osmosis membrane by interfacial polymerization of an MWCNT / MPDA solution and a TMC organic solution according to an embodiment of the present invention.
3 shows the surface modification process of the nanocarbon tube and graphene.
4 is a schematic diagram of a device used for measuring the performance of a reverse osmosis membrane.
FIG. 5 is a graph of IR data after attachment of the raw material and functional groups (carboxyl and amine groups) before attaching the functional groups.
FIG. 6 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane without nanocarbon material before chlorination. FIG.
FIG. 7 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane containing 1 wt% of carbon nanotubes before and after chlorination. FIG.
8 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane containing 2.5 wt% of carbon nanotubes before and after chlorination.
9 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane containing 5 wt% of carbon nanotubes before and after chlorination.
10 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane containing 1 wt% graphene before and after chlorination.
11 is a graph showing changes in the flow rate and salt removal rate of the reverse osmosis membrane containing 2.5 wt% of graphene before and after chlorination.
12 is a graph showing changes in flow rate and salt removal rate of the reverse osmosis membrane containing 5 wt% of graphene before and after chlorination.
FIG. 13 is a graph comparing the current-voltage graph obtained by the CV performed on the existing active layer and the aCNT-containing active layer, before and after exposure to chlorine ions, respectively.
FIG. 14 is a graph comparing a current-voltage graph obtained by CV performed on a conventional active layer and an aGO-containing active layer before and after exposure to chlorine ions, respectively.
15 shows a reverse osmosis membrane coated with an amine group-bonded graphene on the active layer according to the present invention.
16 is an SEM photograph of a reverse osmosis membrane including a polyamide active layer, an active layer coated with a graphene 5 layer having an amine group bonded to its surface, and an active layer coated with a graphene layer having an amine group bonded to the surface thereof.
17 is a TEM photograph of a reverse osmosis membrane including an active layer coated with a graphene 10 layer having an amine group bonded to its surface.
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 PAH / graphene five layers, and an active layer coated with a graphene layer having an amine group bonded thereto .
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 PAH / graphene five layers, and an active layer coated with a graphene layer having an amine group bonded thereto .
FIG. 20 is a graph showing current-voltage graphs obtained by CV results of a reverse osmosis membrane including an active layer coated with PAH / graphene five layers before and after exposure to chlorine ions, respectively.
FIG. 21 is a graph showing a current-voltage graph obtained as a result of CV of a reverse osmosis membrane including an active layer coated with a graphene layer having an amine group bonded on its surface, before and after exposure to chlorine ions.
22 is a schematic view showing the ion removal process before and after exposure of the polyamide active layer coated with graphene to which an existing polyamide active layer and an amine group are bonded.

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 relates to an active layer having a nanocarbon material to which an amine group is bonded, And a support layer composed of a porous support.

Since its discovery in 1991, carbon nanotubes have received unprecedented attention from academia because of their strength over diamonds, extreme large diameter-to-length ratios, and chemically inert properties. In 1993, Bethune Have discovered single-walled carbon nanotubes, which have attracted renewed attention to their electrical properties, opening up a whole new field of application for device applications. In 1998, Wagner et al. Of the Weizmann Institute of Science reported that polymers including carbon nanotubes exhibited significantly improved physical properties compared with general polymers, and research using polymers and carbon nanotube composite materials was activated.

Hereinafter, the structure of a reverse osmosis membrane having an active layer having a nanocarbon material bonded with an amine group on its surface and a method for producing the reverse osmosis membrane will be described in detail.

According to an embodiment of the present invention, there is provided an active layer including a surface to which a nanocarbon material having an amine group bonded thereto is introduced; And a support layer composed of a porous support may be provided. FIG. 1 is a schematic view showing a reverse osmosis membrane active layer formation reaction. As shown in FIG. 1, the active layer has a structure in which an amine-substituted nano carbon material is bonded to an aromatic amine and a polyfunctional acyl halide on the surface. The introduction of such a nanocarbon material greatly improves the strength of the reverse osmosis membrane active layer and can increase the chemical resistance due to the introduction of the substituted amine group on the surface of the nanocarbon material.

According to another embodiment of the present invention, there is provided a semiconductor device comprising: an active layer coated with a nanocarbon material having an amine group bonded to its surface; And a support layer composed of a porous support may be provided.

22 is a schematic view showing the difference in chemical durability due to graphen coating through an ion removing mechanism. As can be seen from FIG. 22, the application of the graphene layer can improve the salt removal rate after chlorine ion exposure by the further introduction of the ion removing layer which is not affected by chlorine ion exposure, and consequently to improve the chlorine resistance.

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

According to an embodiment of the present invention, the carbon nanotube may be a multi-walled carbon nanotube. Multi-walled carbon nanotubes are preferable because they can be mass-produced and can save costs compared to single-walled carbon nanotubes and have better physical properties than single-walled carbon nanotubes.

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

In addition, according to an embodiment of the present invention, the porous support may be a polysulfone ultrafiltration membrane having a pore size of 0.001 to 0.01 탆. If the pore size is less than 0.001 탆, the permeation flow rate is reduced. If the pore size is more than 0.01 탆, it is difficult to form the strength for supporting the active layer.

According to another aspect of the present invention, there is provided a method for preparing a mixed solution comprising: dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;

Adding a nanocarbon material having an amine group to the surface of the mixed solution to prepare a supported solution;

Supporting the porous support on the support solution, and removing the remaining solution; And

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

A method of manufacturing a reverse osmosis membrane may be provided.

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

The present invention includes a step of dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a solution. 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 the hydrochloric acid produced in the polymerization, and may preferably be 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 carboxy group on the surface, followed by the addition of an aliphatic diamine to bond the amine terminal group with a peptide bond. FIG. 3 shows the surface modification process of the nanocarbon tube and graphene.

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

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

On the other hand, when the residual solution is not removed, the remaining solution should be removed since the interfacial polymerization layer is not formed securely on the supporting film and forms an uneven layer after interfacial polymerization. The removal of the residual solution may be carried out using a sponge, an air knife, nitrogen gas blowing, naturally drying, or a compression roll, but is not particularly limited.

The organic solution is then prepared by dissolving the polyfunctional acyl halide in an organic solvent.

As a solvent for the organic solution, hexane, cyclohexane, heptane, alkane, etc., which do not dissolve in water, can be used. In particular, n-hexane (98%) organic solvent is preferred in one embodiment of the present invention.

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

According to the present invention, finally, the support on which the residual solution has been removed is supported on the organic solution to carry out an interfacial polymerization reaction, followed by drying. Such drying is for evaporating the remaining organic solvent, and it is preferable that the drying step is performed at 60 to 80 캜 for 1 to 10 minutes.

It is preferable that the aromatic amine in the aqueous solution is 1 to 20 parts by weight based on 1 part by weight of the polar solvent and the tertiary amine is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polar solvent. If too little of the aromatic amine or tertiary amine is used, the salt removal rate becomes insufficient due to an excessively thin active layer, and if it is used excessively, the permeation flow rate becomes insufficient due to an excessively thick active layer. In addition, the nano carbon material having an amine group bonded to the surface thereof 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 the aromatic amine) based on the weight of the aromatic amine. If it is less than 1 wt%, there is a problem that the chlorine resistance is not significantly increased. If it exceeds 10 wt%, the interfacial polymerization inhibits the formation of dense-crosslinked amide network.

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 weight based on 100 parts by weight of the solvent of the organic solution. In this case, in the case of less than 0.05 part skin, the salt removal rate becomes insufficient due to the too thin active layer, and in the case of 5 parts skin excess, the permeation flow rate becomes insufficient due to the too thick active layer.

The present invention also relates to

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

Supporting the porous support on the mixed solution, and removing the remaining solution;

Supporting the porous support from which the residual solution has been removed in an organic solution in which the polyfunctional acyl halide is dissolved, and drying and forming an active layer on the porous support; And

Forming a nano carbon material multilayer thin film by alternately and repeatedly carrying an aqueous solution of a nano carbon material and an aqueous solution of a nano carbon material having an amine group bonded to the surface of the porous support on which the active layer is formed;

The present invention also provides a method for producing a reverse osmosis membrane.

The method of preparing the reverse osmosis membrane is the same as the reverse osmosis membrane manufacturing method described above except that the nano carbon material is applied to the active layer. The application of the nano carbon material may include an anionic nano carbon material and a cationic aminated nano carbon material Is introduced onto the previously prepared reverse osmosis membrane active layer through a multilayer thin film self-assembly method using an electrostatic attractive force.

Specifically, a substance immersed in a cationic aminated nano carbon material aqueous solution is adsorbed on the surface, and the surface is washed to remove only the remaining material due to a strong attraction force from the surface. It is then immersed in an aqueous solution of anionic nano-carbonaceous material oxide and adsorbed on the surface of the cationic material. And then washed again to form a thin film composed of a cationic nano-carbon material and an anionic nano-carbon material, and the entire process is repeatedly performed to adjust the thickness to a desired value. The reverse osmosis membrane adsorbed by the multi - layered membrane has the advantage of showing excellent chemical durability in terms of salt removal rate as compared with general reverse osmosis membrane.

At this time, it is preferable to use 1 to 10 wt% (1 to 10 parts by weight with respect to 100 parts by weight of aromatic amine) of the aminated nano carbon material to be applied to the aromatic amine. If less than 1 wt% is used, there is a problem that the concentration is low and the lamination is not done correctly. If the content is more than 10 wt%, there is a problem that a uniform solution is not formed due to an excessive amount of the substance.

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  Surface functional attachment of a substance

Carbon nanotubes were used as raw materials for multi-wall CNT (Hanwha Nanotech CM-100). To add functional groups, 2 g of CNT was added to 200 ml of a 3: 1 by volume mixture of sulfuric acid and nitric acid, and the reaction was carried out at 70 ° C. for 24 hours to oxidize the CNT surface. After the reaction, the reaction mixture was diluted with a large amount of distilled water, and then recovered by filtration and dried to obtain MWCNT having a carboxyl group on its surface. The MWCNT thus obtained is subjected again to amine substitution, which is obtained by adding ethylenediamine to the above-prepared carboxylated CNT and adding N, N'-Dicyclohexylcarbodiimide (DCC) as a coupling agent to cause a coupling reaction between the amine and the carboxyl group . The mixture was reacted at room temperature for 24 hours, diluted, filtered and dried in the same manner as the carboxylated CNT to obtain a dried aminated CNT sample.

The functionalized graphene was prepared by the following procedure.

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

To synthesize aminated graphene oxide, ethylenediamine was added to the graphene oxide obtained above and reacted at room temperature in a mixed solution of ethanol and distilled water. Then, as before, aminated graphene oxide was obtained by drying through dilution and filtration.

The functionalized nanocarbon thus formed underwent FT-IR analysis to confirm the attachment of the functional group. Two types of nanocarbons, pristine, oxidated and aminated, were prepared. The samples were prepared in powder form and KBr pellets were prepared and measured using a wavelength band from 4000 cm ^-1 to 400 cm ^-1 .

Carbon nanotubes and graphite powders were chemically treated with functional groups, and the attachment of these functional groups was confirmed by FT-IR. The IR data graph of the original substance and functional group attachment (carboxyl group and amine group) before attaching the functional group is shown in FIG. On the other hand, if the carbon nanotubes in the original sample is not attached to a functional group that particular peak revealed that, in the case of a carbon nanotube sample was attached to a carboxyl group, and the sharp peak characteristic of the carboxyl group (-COOH) also observed in the vicinity of 1700cm ^-1 1600cm A peak of C = O double bond was observed in the vicinity of ^-1 , and it was confirmed that a functional group was generated in this sample. In addition, in the case of the amine group-attached sample, a strong -NH ₂ functional group peak near 1100 cm ^{-1 and} a CO-NH ₂ functional group peak near 1650 cm ^-1 , as well as the C═O double bond peak confirmed in the carboxyl- The carbon nanotubes to which the carboxyl group was attached were confirmed to have an amine functional group by bonding to diamine through amide bond.

Identification of these functional groups was carried out in the same manner for graphene powder with functional groups. As a result, characteristic peaks of ether functional groups were observed at around 1100 cm ^{-1 in} oxidized graphene. 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: Preparation of polyamide / nano-carbon composite reverse osmosis membrane active layer

Two different types of active layers including carbon nanotubes and graphene were fabricated on polysulfone - based supporting films. The supporting membrane was a commercially available product, UE50, model name of TriSep, and an ultrafiltration membrane coated with a 50 μm thick asymmetric pore polysulfone on a 150 μm thick polyester nonwoven fabric was used. It is a filter membrane optimized for spiral-wound type modules and can withstand pressures up to 41 bar. M-phenylene diamine (MPDA,> 99%, Sigma Aldrich) and triethylamine (TEA,> 99.5%, Aldrich) and trimesoyl chloride (TMC, 98%, SigmaAldrich) were used to prepare the polyamide-based active layer.

The surface-substituted MWCNTs and graphenes were added to the polyamide active layer polymerization. First, 200 ml of distilled water was mixed with 2 g of m-phenylenediamine (MPDA) and 1.4 ml of triethylamine (TEA), and 1 to 5 wt% (1 to 5 parts by weight based on 100 parts by weight of MPDA) Of MWCNT or graphene was dispersed through sonication for about 30 minutes to prepare solution (1). Then, 0.13 ml of trimethoyl chloride (TMC) was added to 200 ml of cyclohexane to prepare solution (2). The surface-treated UF membrane was supported on the solution (1) for about 3 minutes to adsorb the solution (1) on the surface, taken out, and the residual solution on the surface was removed through a roll milling machine (manufactured by Samwon Engineering). Then, the solution was further immersed in the solution (2) for 3 minutes to effect interfacial polymerization on the surface of the film to form an active layer. Then, the film sample taken out from the solution was dried at 60 ° C for 10 minutes to evaporate the remaining solvent. The membranes prepared through this process were immersed in distilled water for 30 minutes before measurement and activated, and the performance was measured.

The PAH-containing reverse osmosis membrane was also prepared in the same manner, and the weight of the added PAH was adjusted to 1 to 10 wt% (1 to 10 parts by weight per 100 parts by weight of MPDA) based on the weight of MPDA.

Example 3: Preparation of composite reverse osmosis membrane coated with a graphene layer on a polyamide active layer

An active layer of polyamide material was prepared on a polysulfone based support layer. The supporting layer was obtained by purchasing from TriSep, USA a film for ultrafiltration in which a polyester nonwoven fabric having a thickness of 150 μm was coated with asymmetric porous polysulfone having a thickness of 50 μm. Materials used for the polyamide activation layer were m-phenylene diamine (MPDA,> 99%, Sigma Aldrich), triethylamine (TEA,> 99.5%, Aldrich) and trimesoyl chloride (TMC, 98%, Sigma Aldrich).

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. Then, 0.13 ml of trimethoyl chloride (TMC) was added to 200 ml of cyclohexane to prepare solution 2. The support layer membrane was cleaned of the surface residues through sonication and then loaded on Solution 1 for 3 minutes to adsorb the MPDA on the membrane surface. It was then taken out and the residual solution on the surface was removed through a roll milling machine (manufactured by Samwon Engineering). After the removal, MPDA-adsorbed flat membrane was again supported on Solution 2 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 taken out from the next solution and dried in an oven at 60? For 10 minutes to evaporate the cyclohexane.

The active layer using the graphene with the additional functional group was laminated on the polyamide active layer manufactured through the above process. The graphene with functional groups is prepared by chemically treating the graphite powder, which is carried out through the following procedure.

(99%, Aldrich), Ethylenediamine (> 98%, Aldrich) and Ethanol (Baker) were used as the starting materials. In 2 g of graphite, 17 g of potassium chlorate and 40 ml of nitric acid were mixed and stirred for more than 12 hours. Then, the mixture was diluted with 5 L or more of distilled water, and filtration was repeatedly carried out to produce graphene oxide. One gram of the graphene oxide thus obtained was mixed with 8 ml of Ethylenediamine and 50 ml of Ethanol, followed by stirring for 12 hours. Then, aminated graphene oxide (AGO) having an amine group bonded to the surface was obtained through distillation water dilution and filter purification in the same manner as above.

Graphite oxide and aminated graphene oxide solutions were prepared by dispersing graphene at 1 mg / 1 ml concentration in distilled water at room temperature. Then, this was prepared by titrating the aqueous solution of graphite oxide to pH 3 and the aqueous solution of aminated graphene oxide to pH 8. And pure distilled water was titrated to pH 3 and 8, respectively.

The film containing the polyamide active layer is first carried on an aminated graphene oxide aqueous solution which has been aminated to be adhered for 10 minutes to adhere the grafted oxide layer to the surface. Then, it was washed with distilled water of pH 8 to remove the residue of the surface, and the graphite oxide layer was laminated by carrying it in aqueous solution of graphite oxide of pH 3. Then, it is washed with distilled water of pH 3 to form one layer of amphiphilic graphene oxide and graphene oxide. This process is repeated 5 times or 10 times to form a 5- or 10-layer thin film composed of graphene, an aromatic amine In terms of weight, 5 to 10 wt% of graphene was fixed on the polyamide active layer.

16 and 17, it can be confirmed that the polyamide active layer is coated with the graphene layer.

Experimental Example 1: Performance measurement of polyamide / nano-carbon composite reverse osmosis membrane

The performance of the reverse osmosis membrane prepared in Example 2 was measured. The sodium chloride (NaCl, Aldrich) was dissolved in ultrapure water and the salt concentration was 2,000 ppm. NaCl,> 4% (Sigma-Aldrich) Was used.

The apparatus used for measuring the performance of the reverse osmosis membrane was fabricated and tested by using a test cell, a brine storage tank, a high-pressure pump, and an electronic balance. The overall structure of the apparatus is shown in FIG. The brine in the brine storage tank is supplied to the test cell through the pump, and the brine passing through the cell is returned to the tank. The test cell was made of stainless steel for the purpose of preventing corrosion by salt water, and the effective permeable area was 13.85 cm ² . The structure of the test cell adopts the cross-flow filtration method, in which salt water is flowed in parallel to the permeable membrane to prevent the accumulation of foreign matter that may occur when the membrane is vertically flown . The salt removal rate was calculated by the salinometer (EUTECH PC650), which is the concentration of the saline solution and the product water introduced into the membrane. Respectively. During the experiment, the pressure was fixed at 15.5 bar (225 psi) and controlled under constant control so as to remain constant.

The reverse osmosis membrane was prepared by adding 1 ~ 5% of nano - carbon material to the weight of MPDA, which is one of the polyamide - forming monomers, in the production of polyamide - based reverse osmosis membrane. The measurement was made by flowing a brine of 2,000 ppm in a crossflow type at a pressure of 15.5 bar and measuring the flow rate and concentration of the produced water. The reverse osmosis membrane without the addition of nano-carbon was measured by self- % Salt removal performance and a flow rate of 12.5 L / m ² .

The membranes containing amine - group - bonded carbon nanotubes were tested for 3 wt%, 1 wt%, 2.5 wt% and 5 wt%, respectively, based on the weight of MPDA. As a result, the reverse osmosis membrane containing 1 wt% of amine carbon nanotubes had a salt removal rate of 91.5% and a flow rate performance of 10.1 L / m ² , which were slightly lower than those of the comparative non-added membranes. This degradation of performance was accompanied by an increase in the amount of carbon nanotubes and a salt removal rate of 90.2% and a flow rate of 13.5 L / m ^{2 in} a 2.5 wt% carbon nanotube film and a 83.9% salt content in a 5 wt% carbon nanotube film, respectively Removal rate and flow rate of 12.8 L / m ² , indicating that the performance is weakened with increasing carbon nanotube content.

The same additive concentrations and performance tests as for the amine group-attached carbon nanotubes were also performed on the graphene-added films with amine groups. As a result, stepwise performance weakening similar to the above was observed. That is, the flow rate of 12.1 L / m ² and the salt removal rate of 95.1% in the graphene 1 wt% membrane and the flow rate 13.5 L / m ² , the salt removal rate 90.2% and the flow rate 12.7 L / m ² , and a salt removal rate of 88.7%. From these results, it can be seen that the introduction of additives has some inevitable hindrance to the performance of the reverse osmosis membrane, which is attributed to the morphology change of the reverse osmosis membrane due to the additives.

The chlorine removal performance of the fabricated reverse osmosis membrane was measured by measuring the flow rate and the salt removal performance of each membrane sample. The membrane was immersed in a NaOCl solution of 6,000 ppm for 1 hour to expose the active layer to the attack of chlorine ions. And the performance before and after the loading was compared. As a result of this test, NANOCARBO-free reverse osmosis membrane, which was set as a control, showed a large change in the conventional performance of the flow rate of 42.5 L / m ² and the salt removal rate of 49.1% when the flow rate was 12.5 L / m ² and the salt removal rate was 95.1%. Both the increase in flow rate and the decrease in salt removal rate are evidence that membrane surface active layers are lost, indicating weak bromination of general polyamide based reverse osmosis membranes.

In addition, a markedly improved chlorine resistance was observed in both the carbon nanotube-containing film and the graphene-containing film, compared with the control. In the reverse osmosis membrane with carbon nanotubes, the salt removal rate decreased from 95.1% to 76.4%, from 90.2% to 78.7%, and from 83.9% to 80.0% when the concentration was increased to 1, 2.5 and 5 wt% 15.1%, 11.5%, and 3.9%, respectively, indicating that the decrease in the concentration decreases with increasing concentration of the additive. The increase in the flow rate with the same effect also decreases with the increase of the additive concentration, which increases the flow rate by 35.7 L / m ² at 1 wt%, increases by 26.9 L / m ² at 2.5 wt% and increases by 23.0 L / m ² at 5 wt% Respectively. As a control, the nano-carbon added membrane showed a flow rate of 42.5 L / m ² and a salt rejection rate of 49.1% after measuring the chlorine resistance, compared with the value before measurement, which was increased by 30.0 L / m ² and decreased by 46.0% This is a remarkable effect. The above results can be seen from FIGS. 6, 7, 8 and 9.

In addition, the graphene-containing reverse osmosis membrane sample also showed remarkable increase in chlorine resistance, which can be confirmed from FIGS. 10, 11 and 12. In the case of the reverse osmosis membrane sample prepared with 1 wt% of graphene based on the weight of MPDA, the performance of the flow rate of 12.1 L / m ² and the salt removal rate of 91.7% before the measurement of chlorine resistance was 43.5 L / m ² and 74.4% . In particular, 17.3% of the salt removal rate change was less than 40% of the 46.0% change of the control group. In addition to the above carbon nanotubes, the same phenomenon was observed in the same way as in the above-mentioned carbon nanotubes, and the salt removal performance before and after the measurement of chlorine resistance of the reverse osmosis membrane containing 2.5 wt% of graphene and 5 wt% From 91.2% to 87.8%, from 6%, and 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 removal performance of the fabricated reverse osmosis membrane was measured by measuring the flow rate and the salt removal performance of each membrane sample in 6,000 ppm NaOCl solution for 1 hour to expose the active layer to the attack of chlorine ion, In this experiment, 2,000 ppm NaCl aqueous solution was applied at a pressure of 15.5 bar, and its flow rate and concentration were measured again. As a result of this test, the existing performance of NANOCARBON-DOPO re-osmosis membrane, which was set as the control, was greatly changed to a flow rate of 44 L / m ² and a salt removal rate of 47%, respectively, at a flow rate of 13 L / m ² and a salt removal rate of 96%. In addition, a control group (a reverse osmosis membrane in which a five-layer thin film was formed by self-assembly of PAH (polyarylamine hydrochloride) as a cationic material and graphene oxide as an anionic material] was tested at a flow rate of 12 L / m ² , the salt removal rate was 93%, and the performance was changed to 42 L / m ² and the salt removal rate was 79%, respectively. On the other hand, the reverse osmosis membrane coated with the aminated graphene oxide of Example 2 (about 5 wt% based on the weight of aromatic amine) had a performance of a flow rate of 16 L / m ² and a salt removal rate of 92% ² , and the salt removal rate was 86%. That is, it can be confirmed that the reduction rate is remarkably reduced by about 6% of the salt removal performance before and after the measurement of chlorine resistance.

Experimental Example  2: Cyclic voltammetry  Measure

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

For the cyclic voltammetry measurement, the active layer polymer was formed on the Cr and Au coated Si substrate by a similar method to that of the film. First, the substrate was subjected to an ozone plasma treatment and the mixed solution of MPDA / TEA / additives (MWCNT, graphene, PAH, additive concentration fixed to 1 wt% based on the weight of MPDA) was dropped thereon, Respectively. The TEA / cyclohexane solution was then placed on top to allow interfacial polymerization to occur, and the remaining solution was then washed with a spin coater. The sample thus prepared was dried at 60 ° C for 10 minutes in the same manner as the film sample, and then measured. For each type of additive, some of the samples were exposed to chlorine ions at the same concentration as the chlorination test, damaging the active layer polymer. These samples were tested using a cyclic voltammetry measuring instrument to obtain a current-voltage graph. In addition, the degree of damage of active layer by chlorine ion was compared with each additive.

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

In general, the active layer without additives showed a remarkable change in current peak after chlorine exposure. In general, polyamide does not show a current change due to voltage change because it does not conduct current. This means that the polyamide layer This damage has been shown to cause the current flow through the exposed electrodes below. On the other hand, this phenomenon is observed to be remarkably weakened in other sample electrodes including additives, which is considered to be evidence that the active layer polymer containing the additive is more resistant to the attack of chlorine ions than the general reverse osmosis membrane active layer polymer. Therefore, it is possible to confirm the relatively good chlorine resistance of the reverse osmosis membrane active layer containing nano carbon.

The results of measurement of the cyclic voltammetry of the reverse osmosis membrane prepared in Example 3 are shown in Figs. 20 and 21, and the results are shown in Fig. 20 as a control (PAH (polyarylamine hydrochloride) as the cationic material) The reverse osmosis membrane having a five-layer thin film 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 (13)

delete delete delete delete delete Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;
Adding a nanocarbon material having an amine group to the surface of the mixed solution to prepare a supported solution;
Supporting the porous support on the support solution, and removing the remaining solution; And
Supporting and drying the porous support from which the residual solution has been removed in an organic solution in which the polyfunctional acyl halide is dissolved,
The nanocarbon material having an amine group bonded to the surface thereof may be prepared by treating a nanocarbon material with a strong acid and adding an aliphatic diamine to substitute an amine group on the surface of the nanocarbon material to prepare a reverse osmosis membrane
Dissolving an aromatic amine and a tertiary amine in a polar solvent to prepare a mixed solution;
Supporting the porous support on the mixed solution, and removing the remaining solution;
Supporting the porous support from which the residual solution has been removed in an organic solution in which the polyfunctional acyl halide is dissolved, and drying and forming an active layer on the porous support; And
Forming a nano carbon material multilayer thin film by alternately and repeatedly carrying an aqueous solution of a nano carbon material and an aqueous solution of a nano carbon material having an amine group bonded to the surface of the porous support on which the active layer is formed;
Wherein the method comprises the steps of:
8. The method of claim 7,
Wherein the nanocarbon material having an amine group bonded to the surface thereof is prepared by treating a nanocarbon material with a strong acid and adding an aliphatic diamine to replace the amine group on the surface of the nanocarbon material.
The method according to claim 6,
Wherein the supporting treatment of the support solution or the organic solution is performed for 1 minute to 10 minutes.
8. The method according to claim 6 or 7,
Wherein the removal of the residual solution is performed using any one selected from the group consisting of a sponge, an air knife, nitrogen gas blowing, natural drying, and a compression roll.
8. The method according to claim 6 or 7,
Wherein the drying step is a heat treatment for 1 minute to 10 minutes at 60 ° C to 80 ° C.
8. The method according to claim 6 or 7,
Wherein the nanocarbon material having an amine group bonded to the surface is added in an amount of 1 to 10 wt% based on the weight of the aromatic amine. 8. The method of claim 7,
Wherein the supporting treatment of the mixed solution or the organic solution of the support is performed for 1 to 10 minutes.

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