KR101441540B1 - Polymeric membrane for water treatment embedded with planar carbon-based oxide, and water treatment apparatus and process using the same - Google Patents

Abstract

The present invention reduces filtration resistance due to membrane fouling due to deposition of microorganisms, flocs or organic substances generated on the surface of a separation membrane as well as filtration resistance caused by the physical properties of the polymer membrane itself during the operation of the separation membrane water treatment process, The present invention provides a polymer membrane for water treatment which can be stably operated for a longer period of time by improving the performance, a membrane water treatment apparatus using the same, and a membrane water treatment process. More specifically, the present invention relates to a polymer separator comprising a plate-like carbon-based oxide such as graphene oxide and a derivative thereof capable of increasing the hydrophilicity of the separator and increasing the negative charge on the surface thereof, And more particularly, to a separation membrane water treatment apparatus and process which can operate stably over a long period of time.

Description

TECHNICAL FIELD The present invention relates to a polymer membrane for water treatment comprising a carbon-based oxide, a membrane-type carbon-based oxide, a membrane water treatment apparatus and a membrane water treatment process using the same,

The present invention reduces filtration resistance due to membrane contamination due to deposition of microorganisms, flocs or organic substances generated on the surface of a membrane while reducing the filtration resistance caused by the physical properties of the polymer membrane itself in the membrane membrane water treatment process, The present invention relates to a polymer membrane capable of improving the efficiency of the membrane membrane water treatment process, and a water treatment process using the same. More particularly, the present invention relates to a polymer separator comprising a plate-shaped carbon-based oxide capable of increasing the hydrophilicity of the separator and increasing the negative charge on the surface thereof, and a separator membrane water treatment apparatus and membrane separator which can operate stably over a long period of time And a water treatment process.

Membrane water treatment process such as separation membrane bioreactor process combining membrane separation process in recent membrane water treatment reactor (bioreactor) has advantages such as excellent economical efficiency due to small site area, stability against external impact load, and reduction of sludge production Has been extensively studied as an alternative to existing physicochemical water treatment processes, and has been widely applied to practical processes. For example, over 10 years ago, 4,000 plants were operating globally (Membrane bioreactors for wastewater treatment, IWA Publishing, 2000), and the market size of the MBR process was $ 300 million in 2008, (Membrane Bioreactors: Global Markets, BCC research, 2008), which is expected to grow at an annual average rate of 11%. The market for water treatment membranes is expected to grow at a CAGR of 12% (SERI Economic Focus No. 213, 2008).

However, the membrane water treatment process is generated by covering the surface (including pores) of the membrane finally due to the filtration resistance of the membrane itself (inherent) as well as the attached growth of the microorganisms existing in the water treatment reactor on the surface of the membrane The filtration performance of the membrane deteriorates due to the filtration resistance caused by membrane fouling due to biofilm.

Various studies have been conducted over the past several decades to solve the problem of membrane contamination of biofilm. Conventionally developed methods include physical methods (e.g., aeration) and chemical methods (e.g., the use of flocculants). Using these existing physical / chemical methods can control biofilm formation to some extent in the early stages of biofilm formation, but once the biofilm is formed, these methods have the limitation that it is difficult to control biofilm formation and growth completely have. In addition, in the case of aeration, additional energy is required, and in the case of pre-agglomeration, a separate facility is required, which is also disadvantageous in terms of energy efficiency and economy. In addition, the above methods could not be a fundamental solution due to limitations of physical properties of the polymer membrane itself (for example, hydrophobic characteristics of the membrane surface).

Accordingly, attempts have been made to modify the surface of a separation membrane in order to suppress the formation of a biofilm by inhibiting the attachment of microorganisms or the like, or delaying the attachment of microorganisms or the like to the maximum, and to increase the permeability of the separation membrane . Hydrophilic polymers such as polyvinylpyrrolidone (PVP) may be added to the process of preparing the membrane (B. Chakrabarty et al . , J. Membr. Sci., Vol.315, pp.6-47) The surface of the separation membrane was subjected to plasma treatment (KS Kim et al . , J. Membr. Sci., Vol. 199, pp. 135-145).

In addition, nanomaterials have been used to improve the filtration performance of the membrane itself (IFJ Vankelecom et al . , J. Phys. Chem., Vol. 99, pp. 13187-13192). In particular examples of using the carbon-based nanomaterials to improve the performance of the membrane there are emerging, among the studies was added an oxide of the multi-walled carbon nanotube (MWCNT) the membrane is a prime example (Choi JH et al . , J. Membr. Sci., Vol. 284, pp. 406-415). According to this study, when the multi-walled carbon nanotube oxide is added to the separation membrane, the hydrophilic characteristics of the separation membrane can be improved by various functional groups possessed by the multi-walled carbon nanotube oxide, And the permeability measured by the filtration test for pure water as the filtration performance of pure water.

Nevertheless, in the case of the multi-walled carbon nanotube oxide, the functional groups formed inside the tube can not be used because of the inability to make contact with the polymer material of the separation membrane existing in the outside of the structure (Sandeep Agnihotri et al . , Langmuir, vol.21, 896-904), the ratio of oxygen to carbon is up to 7%, and the oxidation rate (oxygen content) is considerably low (Anya Kuznetsova et al . , J. Am. Chem. Soc., Vol. 123, pp. 10699-10704). There is a limit to improving the filtration performance of the membrane.

J.H. Choi et al., J. Membr. Sci., Vol. 284, pp. 406-415

It is an object of the present invention to solve the above-mentioned problems, and it is an object of the present invention to solve the above-mentioned problems, and to provide a membrane filtration apparatus capable of improving the filtration resistance of the separation membrane itself due to physical properties (hydrophobicity) The present invention relates to a polymer membrane for water treatment which can operate stably for a longer period of time by reducing the filtration resistance due to membrane contamination due to deposition of organic materials and the like and thereby improving the filtration performance of the membrane and to provide a membrane water treatment apparatus and a membrane water treatment process using the same will be.

As a result of intensive research, the present inventors have found that a plate-like carbon-based oxide containing graphene oxide and its derivatives is contained in a separation membrane to impart negative charge and hydrophilicity to the separation membrane to improve water permeability, It is possible to improve the filtration performance of the membrane by alleviating the phenomenon of adhering organic substances and the like in the activated sludge and promoting desorption of the substances adhered to the separation membrane, leading to the present invention.

The present invention provides a separation membrane for water treatment wherein a plate-like carbon-based oxide is contained in a separation membrane composed mainly of a polymer.

The platelet-like carbon-based oxide in the present invention is composed of a carbon-based oxide having a plate-like shape with a large specific surface area per unit mass and having a hydrophilic functional group such as an oxygen-containing functional group introduced by an oxidation treatment. Specifically, there may be mentioned platy carbon-based nano-oxides including graphen oxide and derivatives thereof.

Graphene oxide is an oxide of graphene, a material that forms a two-dimensional planar structure in which carbon atoms are connected in a hexagonal honeycomb shape. Conventionally, graphene and its oxide, graphene oxide, have been used in automotive and aerospace < RTI ID = 0.0 > industries < / RTI > to enhance mechanical strength and elasticity of materials, increase electrical conductivity, thermal conductivity, Industrial, electronic industry, or product packaging, there have been no attempts to apply them to the environmental field, particularly water treatment membranes (Virendra Singh et al . , Progress in Materials Science, vol.56, pp.1178-1271). In the present invention, since graphene oxide has an open structure of a sheet type or planar, unlike a multi-walled carbon nanotube (MWCNT) oxide having a tube shape, all functional groups (Especially oxygen-containing functional groups with negative charge). Furthermore, there is a carboxyl group in the rim portion of the graphene oxide piece, and a large amount of available functional groups in the central portion of the piece in the presence of a carbonyl group and a hydroxyl group (Daniel R. Dreyer et al . , Chem. Soc. Rev., vol.39, pp.228-240), and thus the ratio of oxygen to carbon (oxidation rate) is about 33%, which is much higher than that of MWCNT oxide (Daniel R. Dreyer et al . , Chem. Soc. Rev., vol.39, pp.228-240).

Due to such a feature, if a plate-like carbon-based oxide such as graphene oxide or its derivative is used as a hydrophilicity-imparting additive in a polymer membrane, the effect of imparting hydrophilicity to multi-walled carbon nanotube oxides and other nanomaterials (including their oxides) It also has a higher water permeability and, at the same time, alleviates the hydrophobic or electrostatic interaction (attraction) between the contaminants, which are composed of hydrophobic or negatively charged proteins on the surface, Thereby improving the filtration performance.

Graphene oxide and derivatives thereof, which are typical plate-like carbon-based oxides added to the separator in the present invention, can be obtained, for example, by oxidizing graphite with an acidic solution and an oxidation catalyst. There is no particular limitation on the material of the graphite raw material, and it can be selected from carbon powder, flake, granular or rod shaped product, modified carbon product, and the like. More specifically, it is possible to use graphite powder, graphite flake, granular graphite, graphite rod (for example, Graphite rod from Aldrich), fluorinated graphite (for example, Graphite fluorinated from Aldrich) It is more preferable to use graphite in the form of an unmodified powder in consideration of the fact that it can be oxidized within a short period of time as long as it is a pure material free from impurities other than carbon. The method of oxidizing a platelet-like carbon-based material such as graphite to a platelike carbon-based oxide such as graphene oxide is not particularly limited as long as it is an efficient oxidation (reforming) method, and the methods developed by Brodie, Hummers, or Staudenmaier Dreyer et al . , Chem. Soc. Rev., vol.39, pp.228-240), or a combination of these methods or an improved method can be used. As the acidic solution used for oxidizing the graphite, a mixed solution of sulfuric acid (H ₂ SO ₄ ), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ) or these solutions may be used, and potassium permanganate KMnO ₄ ), or potassium chlorate (KClO ₃ ) may be added.

In the polymer membrane for water treatment of the present invention, it is preferable that the plate-like carbon-based oxide is contained in an amount of 0.2 to 2% by weight based on the weight of the entire separation membrane. If the content of the plate-like carbon-based oxide is less than 0.2 wt%, hydrophilicity and negative charge of the platelike carbon-based oxide are not sufficiently imparted to improve the filtration performance of the separation membrane. If the content exceeds 2 wt%, the polymer As the viscosity of the raw material solution is greatly increased, the introduction of the non-solvent into the polymer solution is impeded or the polymer rearrangement may occur over a long time due to a slow diffusion rate, so that the membrane skin layer becomes denser, have.

The separator for water treatment of the present invention is not particularly limited to the type, module, pore size and the like as long as the plate-like carbon-based oxide can be contained. Symmetric and asymmetric membranes, and can be applied to conventional modules such as an external pressure type, an immersion type, a flat plate type, a spiral type, and a hollow fiber type which are conventionally used for water treatment. Also, it can be applied to various pore separation membranes such as reverse osmosis membrane (RO), nanofiltration membrane (NF), ultrafiltration membrane (UF), and microfiltration membrane (MF). However, due to improvement in filtration performance of the membrane itself, An ultrafiltration membrane or a microfiltration membrane is preferable in that it can be obtained by maximizing the effect of reducing membrane fouling and the like.

The polymer to be the main body of the polymer separator for water treatment of the present invention is not particularly limited as long as it can be effectively mixed with the platelet-like carbon oxide to form a separator. Examples of the polymer include polyamide, polysulfone, polycarbonate, Cellulose acetate and the like may be used.

The method for producing the separator in the present invention is not particularly limited and may be selected from the group consisting of NIPS (nonsolvent induced phase separation), TIPS (thermally induced phase separation), interfacial polymerization interfacial polymerization, stretching, track etching, and the like can be used. Among them, it is more preferable to use a phase transformation method by a solvent exchange method, which is widely used commercially, in order to produce an asymmetric separation membrane which is a representative water treatment separation membrane.

In the case of the asymmetric separation membrane formed by disposing the skin layer on the porous support layer, the plate-shaped carbon-based oxide may be dispersed in the polymer solution, and then the polymer solution may be solidified on the porous support layer. The solvent of the polymer solution is not particularly limited as long as it is capable of uniformly dissolving the above-mentioned polymers, and organic solvents such as NMP, DMF, DMSO, and DMAC can be used. The material of the porous support layer is not particularly limited as long as it is a material which is not soluble in an organic solvent commonly used in the production of an asymmetric separation membrane, and polyester, polypropylene, or woven fabric can be used.

The method for producing a water treatment separator according to the present invention will be described in more detail with reference to an asymmetric separator. The method comprises the steps of oxidizing a plate-like carbonaceous material such as graphite to plate-like carbonaceous oxide such as graphene oxide, Preparing a polymer solution in which the carbon-based oxide is uniformly dispersed, coating the polymer solution on a porous support, and solidifying the solution to prepare a separation membrane containing a platelike carbon-based oxide.

The method of preparing a polymer solution in which a plate-like carbon-based oxide such as graphene oxide is uniformly dispersed is not particularly limited as long as it is a method capable of uniformly dispersing a platelike carbon-based oxide such as graphene oxide while dissolving the polymer in a solvent However, when the plate-like carbon-based oxide is dispersed after preparing the polymer solution first, since the viscosity of the polymer solution is high, there is a possibility of resistance to dispersion of the plate-shaped carbon-based oxide. Therefore, It is more preferable to prepare a polymer solution by dissolving a solid polymer in a sufficient amount after the treatment.

The present invention also relates to a separation membrane water treatment apparatus comprising a reaction tank for containing water to be treated and a separation membrane module for water treatment, wherein the separation membrane module for water treatment is provided with a separation membrane having a water- Water treatment apparatus.

Further, the present invention is a separation membrane water treatment process comprising filtering the water to be treated through a separation membrane module for water treatment, wherein the separation membrane module for water treatment is provided with a membrane separation membrane having a water- Provides a water treatment process.

When the water treatment separator containing the plate-shaped carbon-based oxide of the present invention is applied to the separation membrane water treatment process including the separation membrane bioreactor process, filtration performance of the separation membrane itself is improved, and membrane contamination on the separation membrane surface is effectively suppressed / The water treatment process can be performed more stably over a long period of time.

1 is a conceptual diagram of a water treatment separator containing graphene oxide as an embodiment of the present invention.
FIG. 2 is a photograph showing a state in which graphene oxide is dispersed on a polysulfone polymer solution during the production of a water treatment separator containing graphene oxide, which is an embodiment of the present invention.
FIGS. 3 and 4 are WFM and SEM photographs showing the state where graphene oxide is located on the surface of the water treatment separator according to one embodiment of the present invention, FIG. 5 shows a spectrum of Raman spectroscopy on the surface of the separation membrane, The results of zeta potential measurement on the membrane surface are shown.
FIG. 7 is a photograph showing a water-treating separator containing different contents of graphene oxide in the examples and comparative examples of the present invention mounted on the module.
8 is a view showing the configuration of an apparatus for conducting water permeability test of the separation membrane in Example 1 of the present invention.
FIGS. 9, 10 and 11 are graphs showing experimental results of water permeability, pore size distribution and microbial adhesion of the separation membrane in Example 1 of the present invention. FIG.
12 is a view showing an apparatus implementing an embodiment of a separation membrane water treatment process using the separation membrane for water treatment of the present invention.
FIGS. 13 to 15 are diagrams showing the increase in the inter-membrane pressure difference (increase in membrane contamination) during the separation membrane bioreactor operation of Examples 2 to 4 of the present invention.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[Preparation of separation membrane containing graphene oxide]

Manufacturing example

As a raw material of graphite, graphite in the form of powder was used (Aldrich), a method of appropriately improving the method by Hummers (Daniel R. Dreyer et al. , Chem. Soc. Rev., vol.39, pp.228-240) To prepare graphene oxide, and then a separation membrane was prepared by phase transformation using a solvent exchange method.

Polysulfone (Solvay Korea) was added to the graphene oxide-dispersed NMP solution, and then the polysulfone was dissolved by stirring at 60 DEG C for one day to obtain a polymer solution in which graphene oxide was dispersed (85 parts by weight of NMP solvent, 15 parts by weight, graphene oxide 0, 0.02, 0.04, 0.17 and 0.34 parts by weight) was prepared. The prepared polymer solution was coated on a porous support using a casting knife and then solidified by immersion precipitation so that graphene oxide in the total weight of the separator was 0 wt%, 0.14 wt%, 0.28 wt% %, 1.13 wt%, and 2.26 wt%, respectively.

(WFM (Wide Field Microscopy) (FIG. 3) and SEM (Scanning Electron Microscope) photographing (FIG. 4) were conducted on the separation membrane containing 2.26% by weight of graphene oxide in the total weight of the separation membrane. As a result, Oxides were found to be contained. Further, as a result of measuring the spectrum using the Raman spectroscopy (FIG. 5), a characteristic peak called a so-called D (defect) peak appears as compared with the case where graphene oxide is not added, It was confirmed that graphene oxide was contained.

In addition, the oxygen content of the membrane surface and cross section was measured using energy dispersive spectroscopy (EDS). As a result, it was found that the addition of graphene oxide increased the oxygen content not only on the surface of the membrane but also over the entire membrane (Table 1). As a result of measurement of the zeta potential on the surface of the membrane (number of trials = 10), the zeta potential of the surface of the membrane was increased by graphene oxide addition (FIG. 6). This means that the oxygen-containing functional groups contributing to the negative charge are effectively introduced into the separation membrane due to the inclusion of graphene oxide.

Oxygen content of membrane surface by EDS (at.%) ^* Measured value (5 times average) Content of graphene oxide (% by weight) The oxygen content of the membrane surface The oxygen content of the membrane section 0 13.76 14.42 0.14 13.82 14.53 0.28 14.27 14.93 1.13 14.48 16.59 2.26 14.8 17.69

*: Percentage of oxygen atoms relative to the total number of atoms of carbon, oxygen and sulfur

The color of the membrane was also varied depending on the content of graphene oxide. The separation membrane having 0, 0.28, and 1.13 wt% of graphene oxide was attached to the polysulfone polymer module (FIG. 7), and the graphene oxide content It is confirmed that the polymer separator contains graphene oxide because the color of the separator becomes dark brown which is the color of graphene oxide.

Example 1

[Water permeability and pore distribution evaluation of membrane]

The water permeability test was conducted on each of the polysulfone membranes for water treatment containing graphene oxide prepared by the above method using a stirred tank of a dead end type.

Specifically, by applying a pressure of 0.2 bar to 1 bar to a tank containing ultrapure water using a compressed nitrogen bomb as shown in FIG. 8, ultrapure water in the tank was introduced into a stirred cell (Amicon 8010, membrane area: 4.91 cm ² , cell volume: 10 mL, maximum permissible pressure: 75 psi). The ultrapure water that has flowed into the stirring cell through the membrane is then filtered, and the filtered ultrapure water is moved to the scale and finally the amount thereof is measured by a computer connected to the scale. The water permeability (unit: ℓ · m ^-2 · h ^-1 , ie, LM ^-2 H ^-1 ) was calculated based on this value.

The distribution of the pore size of the separation membrane was measured for each separation membrane.

[Evaluation of microbial adhesion to membrane]

Experiments were conducted using a concurrent downflow contactor (CDC) reactor (manufactured by BioSurface Technology Corp.) to evaluate the resistance of the polymer membrane for water treatment of the present invention to microbial adhesion. Specifically, PAO1 with green fluorescence was grown in a 1/10 TSB, diluted to an OD of 0.14, and inoculated into a CDC reactor filled with 300 mL of 1/100 TSB. Each membrane was then placed in a CDC reactor and incubated at 25 ° C and 100 rpm for one day. After 24 hours, a feed solution of 1/300 TSB was injected at a rate of 1.4 mL / min, and microorganisms adhered to the membrane and grown.

Comparative Example 1

Evaluation of pore water permeability, pore size distribution and degree of microbial adhesion were performed in the same manner as in Example 1 except that the polysulfone membrane prepared without adding graphenoxide to the polymer solution was used (number of trials = 9 ).

The results of the water permeability evaluation of the membrane are shown in FIG. 9, which agrees with the general tendency that the water permeability increases linearly with increasing pressure. However, when the content of graphene oxide is lower than a predetermined level (0.14, 0.28, or 1.13 wt%), the effect of improving the water permeability is more remarkable as the higher the pressure, the higher the content of graphene oxide (2.26% by weight), the water permeability was lowered due to the addition of graphene oxide.

The evaluation results of the pore size distribution of the separator are shown in FIG. 10. As in the case of the water permeability evaluation, when the content of graphene oxide is lower than a predetermined level (0.14, 0.28, or 1.13 wt%), (2.26% by weight), the pore size of the separator was rather reduced due to the addition of graphene oxide.

The reason why the excess water content and pore size distribution are rather deteriorated when the above-mentioned excessive amount of graphene oxide is added has not been elucidated in detail. However, due to the addition of excess graphene oxide during the production of the polymer membrane by the phase transfer method, This is because the viscosity of the solution is greatly increased so that the non-solvent is prevented from flowing into the polymer solution, or the diffusion rate is slowed due to the increased viscosity, and the rearrangement of the polymer occurs over a long period of time and the membrane skin layer becomes denser I guess.

Further, it was confirmed that as the content of graphene oxide increases in the total weight of the separator, the degree of microbial adhesion is substantially alleviated (FIG. 11). As a result, the high negative charge on the surface of the separator membrane imparted by graphene oxide, It is presumed that this is due to the electrostatic repulsion between the negative charges on the surface.

Example 2 and Comparative Example 2

[Separation membrane bioreactor water treatment process using the separation membrane of the present invention]

The graphene oxide-containing polysulfone separator (Comparative Example 2) and the graphene oxide-free polysulfone separator (graphene oxide content: 0.28 wt% and 1.13 wt% in Example 1) 12, a lab-scale membrane bioreactor (MBR) process was implemented. Specifically, the activated sludge was inoculated in a 6 L sized acrylic reactor and then the synthetic wastewater in the synthetic wastewater tank (see Table 2) was supplied to the reactor using the pump, and at the same time, the separation membrane module The filtration was carried out in such a way that the filtered water of the level of gray water was obtained under the operating conditions of obtaining a constant flux of 16 LM ^-2 H ^-1 through an area of 80 cm ² . The filtered water from the module was discharged to the outside according to the level in the membrane bioreactor through the 3-way valve or circulated to the inside of the reactor. The chemical oxygen demand (COD) of the synthetic wastewater using glucose as the main carbon source was about 530 ppm, and the activated sludge was collected from the Sihwa Sewage Treatment Plant in Gyeonggi Province and fully acclimated to the synthetic wastewater. The degree of membrane contamination in the membrane water treatment process was evaluated by the transmembrane pressure (TMP) of the membrane according to the operation time.

Composition of synthetic wastewater compound Concentration (g / L) glucose 0.4 Yeast extract 0.01 Bactopeptone 0.1 (NH _{4) 2} SO ₄ 0.1 KH ₂ PO ₄ 0.02 MgSO ₄ + 7H ₂ O 0.03 FeCl ₃ + 6H ₂ O 0.0001 CaCl ₂ + 2H ₂ O 0.003 MnSO ₄ + 5H ₂ O 0.003 NaHCO ₃ 0.3

The results of the evaluation of filtration performance of the separation membrane bioreactor process are shown in Fig. In the case of the general separation membrane containing no graphene oxide (Comparative Example 2), unlike the case of the present invention in which 0.25% by weight and 1.13% by weight of graphene oxide are contained, unlike the case of reaching a differential pressure of 50 kPa only by short- (Example 2), the rising speed of the inter-membrane pressure difference was remarkably reduced, and it was found that the inter-membrane pressure difference of 50 kPa was reached after a longer period of operation. That is, in the case of the polymer membrane containing graphene oxide, the filtration performance of the membrane bioreactor process is considered to be increased due to the increase of the hydrophilicity and the negative charge due to graphene oxide and the enlargement of the pore size.

Example 3, Comparative Example 3A Comparative Example 3B

Separately from Example 2, the graphene oxide-containing polysulfone separator (graphene oxide content: 0.28 wt% in the total weight of the separator - Example 3) of the present invention obtained by the above method and the graphene oxide- Comparative Example 3A) and a reduced polysulfone membrane (Reduced Graphene Oxide (RGO) obtained by reducing the graphene oxide prepared in the Preparation Example) to a polymer solution (RGO content in the total weight of the separator: 0.28 Weight% - Comparative Example 3B) was operated to evaluate the filtration performance. The filtration performance was evaluated by operating the separation membrane bioreactor water treatment process of Example 2.

The results of the evaluation of filtration performance of the membrane bioreactor process are shown in Fig. In the case of the separator prepared by adding reduced graphene oxide (RGO) other than graphen oxide (Comparative Example 3B), not only the graphene oxide containing polysulfone separator of the present invention (Example 3) but also graphene oxide- The filtration performance deteriorated rather than the sulfonated membrane (Comparative Example 3A), which is different from that in which graphene oxide has an oxygen-containing functional group contributing to negative charge, and these reduced oxygen-containing functional groups are reduced in the reduced graphene oxide, The reason for this is that the electrostatic attraction between the hydrophobic and the material with the low negative charge, which is the cause of the membrane contaminant, is rather increased because of almost no zeta potential or negative charge.

Example 4, Comparative Example 4A and Comparative Example 4B

Separately from Examples 2 and 3, the graphene oxide-containing polysulfone separation membrane of the present invention (graphene oxide content: 0.28 wt% in the total weight of the separation membrane - Example 4) obtained by the above method and the graphene oxide- (Comparative Example 4A) and a polysulfone separator prepared by adding an oxide of multi-walled carbon nanotube (MWCNT) (JH Choi et al. ) To a polymer solution instead of the graphene oxide prepared in the above Preparation Example The carbon nanotube content in weight: 0.28% by weight - Comparative Example 4B) was operated to evaluate the filtration performance of the separation membrane bioreactor of Example 2.

The results of the filtration performance evaluation of the separation membrane bioreactor are shown in Fig. In the case of the separator prepared by adding the multi-walled carbon nanotube oxide corresponding to the carbon-based oxide similar to graphene oxide but not the plate-like carbon-based oxide (Comparative Example 4B), the graphene oxide-free polysulfone separator 4A), the degree of improvement of the filtration performance was remarkably reduced as compared with that of the polysulfone membrane containing the same amount of graphene oxide (Example 4A) It is presumed that the multi-walled carbon nanotube oxide is remarkably low in oxygen-containing functional groups, and thus the electrostatic attractive force with the substance causing the film contamination is relatively less reduced.

Claims (7)

Wherein the platelet-like carbon-based oxide containing graphene oxide and a derivative thereof is contained in an amount of 0.2 to 2% by weight based on the total weight of the separation membrane. delete The method according to claim 1,
Wherein the polymer comprises at least one member selected from the group consisting of polyamide-based, polysulfone-based, polycarbonate-based, fluorine-based, and cellulose acetate-based polymers. delete The method according to claim 1,
Wherein the separation membrane is a microfiltration membrane or an ultrafiltration membrane. A separation membrane water treatment apparatus comprising a reaction tank for containing water to be treated and a separation membrane module for water treatment,
Wherein the water treatment membrane module comprises the polymer membrane for water treatment according to claim 1, claim 3 and claim 5. A separation membrane water treatment process comprising filtering a treated water through a separation membrane module for water treatment,
The separation membrane water treatment process according to any one of claims 1, 3, and 5, wherein the polymer membrane for water treatment is mounted on the separation membrane module for water treatment.

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