KR20200094717A - Enzyme-based membrane with biocidal activity on surface for water treatment and method for manufacturing thereof - Google Patents

Abstract

The present invention relates to a membrane for water treatment, and more specifically, to a membrane for water treatment having a surface antibacterial activity having biocidal activity, and a method for manufacturing the same.

Description

Enzyme-based membrane with biocidal activity on surface for water treatment and method for manufacturing thereof

The present invention relates to a membrane for water treatment, and more particularly, to a membrane for water treatment having a surface antimicrobial activity having biocidal activity and a method for manufacturing the same.

Membrane filtration technology is a core process of water treatment and is widely applied in various industries. However, as the membrane operation progresses, microbial secretion of extracellular polymeric substances (EPS) from the membrane filtration surface begins to attach, and finally, a biofilm having a thickness of about several tens of micrometers. ) To form a membrane (biofouling), which causes problems such as reduced permeability, shortened membrane life, and increased energy consumption required for filtration, thereby deteriorating the performance and economic efficiency of the membrane process.

To solve this problem, conventionally, a method of physically removing (aeration, backflushing) the formed biofilm and a method of cleaning the membrane using chemicals (acid, base, oxidizing agent) were used.

However, conventional membrane physical and chemical antibacterial and sterilization techniques have limitations in biofilm removal. Specifically, microorganisms are attached to the membrane through an adhesive extracorporeal polymer material, and the adhesive extracorporeal polymer material layer acts as a barrier to physical impact applied to the outside, thereby making it difficult to remove through a physical method. In addition, in the case of a method using chemicals, there is a problem that corrosion of a water treatment facility is caused by excessive use or misuse of chemicals, or environmental pollution and safety of workers due to chemicals are used.

Accordingly, recently, a method of achieving a high antibacterial or antiseptic effect by selectively controlling physiological actions of various microorganisms involved in biofilm formation using enzymes has been studied. This method can prevent environmental pollution due to the eco-friendliness of the enzyme, and has the advantage of being harmless to worker safety.

Looking at the aspect in which the above enzyme is applicable to the actual filtration system, it is possible to consider a method in which an enzyme or a microorganism producing an enzyme is immobilized into a filtration system, but the enzyme or microorganism immobilized carrier is dispersed. There is a problem that it is difficult to separate, recover and reuse it in a situation.

As another aspect, a method of immobilizing an enzyme on a filtration surface of a membrane may be considered. This method has the advantage of being able to maximize the antimicrobial or sterilization efficiency by directly controlling the microbial contamination on the filtration surface, and can be used without modification or additional treatment of the existing filtration system.

However, it is difficult to attach an antibacterial enzyme to the membrane filtration surface through an enzyme immobilization/stabilization technique known to date. Specifically, a commercially available membrane material does not have a chemical functional group for binding to fix an antibacterial enzyme.

In addition, if the membrane material is modified for forming functional groups, additional coating and plasma treatment may cause increased membrane permeation resistance and damage to the membrane structure.

Further, since the surface area of the membrane to which the antibacterial enzyme can be fixed is limited, the removal through the conventional method is insufficient to remove the biofilm formed on the membrane filtration surface.

In addition, for the purpose of filtration, the membrane should be a substrate having a flow path, and according to a method of binding with an antimicrobial enzyme, the pore structure is narrowed or blocked due to a change in the pore structure of the membrane.

Furthermore, it is inevitable that the activity of antibacterial enzymes is deteriorated by long-term continuous operation.

Accordingly, there is an urgent need to research new ways to solve the problems of the conventional enzyme immobilization/stabilization technology while using eco-friendly antibacterial enzymes.

Republic of Korea Patent Publication No. 10-2000-0036726

The present invention was devised in view of the above points, and it is an object to provide a membrane having high sterilization performance and a method for manufacturing the same by minimizing or preventing an increase in permeation resistance and maximizing the amount and stability of antibacterial enzyme per membrane filtration area. have.

In order to solve the above-described problems, the present invention provides antimicrobial activity including a porous media, a polydopamine coating layer coated on at least a portion of the surface of the porous media, and an antimicrobial enzyme-structure complex fixed to the porous media through the polydopamine coating layer. It provides a membrane for water treatment having a.

According to an embodiment of the present invention, the porous media may have an average pore size of 0.01 ~ 10㎛.

In addition, the porous media is polyvinylidene fluoride (polyvinylidene fluoride), polyvinyl alcohol (polyvinylalcohol), polyvinyl acetate (polyvinylacetate), polymethyl methacrylate (polymethylmethacrylate), polyacrylonitrile (polyacrylonitrile), polyvinyl Pyrrolidone (polyvinylpyrrolidone), polytetrafluorethylene, polyimide, polyethylene oxide, polysulfone, poly ether sulfone, cellulose acetate , Cellulose acetate butyrate, cellulose acetate propionate, aluminum oxide (Al ₂ O ₃ ), silicon carbide (Silicon Carbide), silicon nitride (Silicon Nitride), zirconium oxide (ZrO ₂ ) And it may be formed of one or more compounds selected from the group consisting of titanium oxide (TiO ₂ ).

In addition, the antimicrobial enzyme-structure complex may be provided to be fixed to the outer surface portion of either side of the porous media. In one example, the antimicrobial enzyme-structure complex may be an antimicrobial enzyme crosslinked body disposed to surround the structure. In addition, preferably, the antimicrobial enzyme crosslinked product may be a crosslinked antimicrobial enzyme precipitated through a precipitating agent.

In addition, the structure is selected from the group consisting of carbon nanotubes, graphene, graphene oxide, activated carbon, polymer nanofibers, nanoporous particles, silica particles, aluminum particles, silver nanoparticles, gold nanoparticles, magnetic nanoparticles, and zeolites. It may contain one or more.

In addition, the structure may be plate-shaped, for example, graphene, graphite, graphene oxide, or reduced graphene oxide.

In addition, the antibacterial enzyme is glucose oxidase, pyranose oxidase, hexose oxidase, galactose oxidase, cholesterol oxidase, xanthine oxidase, alcohol oxidase, aryl alcohol oxidase, vanillyl alcohol oxidase, veratril alcohol Oxidase, NAD(P)H oxidase, gulonolactone oxidase, pyridoxine oxidase, hydroxy oxidase, choline oxidase, glycerol-3-phosphate oxidase, arabino-lactone oxidase, glyoxal oxidase, Aldehyde oxidase, oxalate oxidase, aryl aldehyde oxidase, L-amino acid oxidase, L-glutamate oxidase, polyamine oxidase, hydroxylamine oxidase, thiol oxidase, glutathione oxidase, cytochrome C oxidase, alcohol It may include any one or more antibacterial enzymes selected from the group consisting of dehydrogenase and cellobiose dehydrogenase.

In addition, the size of the structure may be 0.001 ~ 100㎛.

In addition, the structure of the antimicrobial enzyme-structure complex per unit area (m 2) may be provided in an amount of 0.004 to 14 g.

In addition, the present invention (1) by treating the dopamine solution on the porous media to form a polydopamine coating layer, and (2) by treating a solution containing an antimicrobial enzyme-structure complex on the porous media formed with a polydopamine coating layer It provides a method for producing a membrane for water treatment having an antibacterial activity, comprising the step of fixing the antimicrobial enzyme-structure complex to a polydopamine coating layer.

According to an embodiment of the present invention, the step (2) may include a decompression filtration process in which the solution is formed to form a flow through the porous media having a polydopamine coating layer formed in one direction.

In addition, the present invention provides a water treatment module comprising a membrane for water treatment having antibacterial activity according to the invention.

According to the present invention, the above-described antibacterial enzyme-structure complex can suppress the microbial contamination on the membrane surface and finally improve the filtration performance, so it is possible to operate the water treatment device that is stable for a long period of time compared to the conventional membrane for water treatment. It can be used in industrial engineering systems where the prevention of microbial contamination of water treatment systems is directly related to productivity.

1 is a schematic diagram showing the manufacturing process of an antimicrobial enzyme-structure complex included in an embodiment of the present invention.
2 is a schematic view showing a manufacturing process of a membrane for water treatment according to an embodiment of the present invention.
3 is a graph showing the results of enzyme activity measurement of an antibacterial enzyme-structure complex included in an embodiment of the present invention.
4 is a schematic diagram showing a method for evaluating the antibacterial performance of a membrane.
5 and 6 of the membrane (EAPC (0.1)) according to Example 1 and the membrane (PVDF) according to Comparative Example 1 after the culture for 6 hours in the method of FIG. 4, of the P.aeruginosa bacteria attached to the membrane surface Viability is an image observed with a confocal laser scanning microscope (CLSM).
7 is a schematic view showing a method and apparatus for evaluating the antimicrobial performance of a membrane through trans-membrane pressure (TMP) in constant flux operation.
8 and 9 quantitatively compare the antimicrobial performance of a membrane for water treatment according to an embodiment and a comparative example of the present invention by measuring trans-membrane pressure (TMP) in constant flux operation. As a graph, FIG. 8 is a graph showing the intermembrane pressure measured for a membrane 6 hours after the formation of a biofilm due to P.aeruginosa was induced, and FIG. 9 shows the formation of a biofilm due to S. aureus It is a graph showing the inter-membrane pressure measured on the membrane after 6 hours of induction.
10 is a scanning electron microscope photograph of a surface for a membrane for water treatment according to an embodiment and a comparative example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein.

The membrane for water treatment having antibacterial activity according to an embodiment of the present invention is a porous media, a polydopamine coating layer coated on at least a portion of the surface of the porous media, and an antimicrobial enzyme-structure fixed to the porous media through the polydopamine coating layer It is implemented including a complex. The membrane for water treatment having antibacterial activity refers to a membrane capable of preventing the attachment and growth of contaminants on the membrane surface by microorganisms through biological antibacterial action. In addition, in order to express antibacterial performance, an antimicrobial enzyme is provided on the membrane, but the antimicrobial enzyme content per unit area of the membrane is significantly increased by introducing the antimicrobial enzyme into the porous media in the form of an antimicrobial enzyme-structure complex, and the enzyme is stably extended for a long time. It is advantageous to maintain activity. Furthermore, in order to fix the antimicrobial enzyme to the porous media, the antimicrobial enzyme-structure complex can be very easily introduced to the surface of the porous media through a polydopamine coating layer without additional modification treatment such as functional group generation in the porous media.

The porous filter medium is for filtering targeted filtration materials contained in raw water, and can be used without limitation in the case of a known filter material having a porous flow path through which raw water can pass.

The porous media may be used without limitation in the case of a polymer compound used in the production of known filters, but for example, polyvinylidene fluoride, polyvinylalcohol, polyvinylacetate, polymethyl Methacrylate (polymethylmethacrylate), polyacrylonitrile, polyvinylpyrrolidone, polytetrafluorethylene, polyimide, polyethylene oxide, polysulfone ( polysulfone, poly ether sulfone, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, aluminum oxide (Al ₂ O ₃ ), carbonization Silicon (Silicon Carbide), silicon nitride (Silicon Nitride), may be formed of one or more compounds selected from the group consisting of zirconium oxide (ZrO ₂ ) and titanium oxide (TiO ₂ ). In addition, the porous media is the compound illustrated above The porous structure may be realized by removing the pore-forming agent from the matrix formed through the pore forming agent, or may be a fiber aggregate such as a non-woven fabric, for example, produced by accumulating fibers made of the exemplified compound. It is not limited.

In addition, the porous media may have an appropriate pore size and porosity in consideration of the size, flow rate, and mechanical strength of the target filtration material, for example, an average pore size of 0.01 to 10 μm, more preferably 0.01 to 5 μm. , More preferably, it may be 0.01 ~ 2㎛, it may be advantageous to simultaneously express the excellent flow rate and antibacterial performance even when the antimicrobial enzyme-structure complex described later is introduced.

In addition, the porous media has a thickness of 10 to 1000 μm, and the basis weight may be 10 to 50 g/m 2 but is not limited thereto, and may be appropriately changed in consideration of flow rate and mechanical strength.

Next, the antimicrobial enzyme-structure complex introduced into the above-described porous media will be described.

When an untreated free antifouling enzyme is used in combination with a membrane, the amount of the introduced antibacterial enzyme is significantly reduced, so that the antibacterial performance may be remarkably low or the antibacterial performance may not occur. . In addition, due to changes in the enzyme structure due to changes in the external environment, enzymatic activity loss rapidly progresses, and enzyme stability decreases rapidly within a short period of time, thereby losing antibacterial performance.

However, the antimicrobial enzyme-structure complex can significantly increase the amount of antimicrobial enzyme introduced per unit area of the membrane to the extent that it can express antimicrobial activity, and at the same time significantly improves the stability of the antimicrobial enzyme introduced, so that the activity of the antimicrobial enzyme is maintained even during long-term water treatment This has the advantage of preventing loss.

The antimicrobial enzyme-structure complex may be an antifouling enzyme immobilized on the surface or inside the structure. For example, the antimicrobial enzyme-structure complex may be in the form of two-dimensionally fixed antibacterial enzyme on the surface of the structure. At this time, the fixing may be a physical bond such as adsorption (eg, EA in FIG. 1) or a chemical bond between a functional group and an enzyme provided on the structure.

Alternatively, as another example, the antimicrobial enzyme-structure complex may have a form in which an antimicrobial enzyme is immobilized three-dimensionally on the surface of a structure, and specifically, an antimicrobial enzyme crosslinker may be arranged to surround the structure. At this time, the antimicrobial enzyme cross-linked body is a non-immobilized antimicrobial enzyme between the non-immobilized antimicrobial enzyme and a non-immobilized antimicrobial enzyme through a cross-linking agent while the antimicrobial enzyme is fixed on the surface of the structure in two dimensions It may be formed of (eg, EAC of Figure 1). The crosslinking agent is a non-limiting example, diisocyanate, dianhydride, diepoxide, dialdehyde, diimide, 1-ethyl-3-dimethyl aminopropylcarbodiimide, glutaraldehyde, bis (imido ester) , Bis (succinimidyl ester) and diacid chloride.

In addition, a precipitating agent may be used to provide an antimicrobial enzyme in an amount sufficient to express antibacterial activity by remarkably increasing the amount of the non-fixed antimicrobial enzyme that is crosslinked, and thus the antimicrobial enzymes precipitated A conjugate can be formed (eg, EAPC in FIG. 1). At this time, the precipitating agent can be used without limitation in the case of a known material for precipitating the enzyme, and as a non-limiting example, methanol, ethanol, 1-propanol, 2-propanol, butyl alcohol, acetone, PEG, ammonium sulfate , Sodium chloride, sodium sulphate, sodium phosphate, potassium chloride, potassium sulphate, potassium phosphate, and aqueous solutions thereof may be a single or mixed mixture. In this case, the precipitating agent is 0.28 g/ml to 0.62 g/ml, more preferably 0.38 g/ml to 0.62 g/ml, more preferably, after treatment, for example, when treated to precipitate glucose oxidase. It can be treated with 0.48 ~ 0.52g / ㎖, the antimicrobial enzyme crosslinked material implemented through this is very excellent in enzyme activity, it may be advantageous to express excellent antibacterial activity even after being introduced into the membrane. If the precipitating agent concentration is out of the desired range, a significant decrease in enzyme activity may be caused (see FIG. 3).

On the other hand, even when the antibacterial enzyme forms a three-dimensional crosslinked product through a crosslinking agent, it may be difficult to express sufficient antibacterial activity to kill microorganisms located on or near the membrane surface. Accordingly, preferably, the antimicrobial enzyme-structure complex may be more advantageous in that antimicrobial enzymes precipitated through a precipitating agent form a crosslinked product through a crosslinking agent.

Alternatively, the antimicrobial enzyme-structure complex may be an antimicrobial enzyme immobilized inside and/or outside a porous or hollow structure.

The antibacterial enzyme (biocidal enzyme) refers to an enzyme capable of preventing the attachment and growth of contaminants on the surface of a material through a biological sterilization action by directly inducing the death of microorganisms that cause microbial contamination to generate a biofilm. do. The antimicrobial enzyme may be used without limitation in the case of a known enzyme that directly or indirectly induces the death of a known microorganism that causes microbial contamination to generate a biofilm.

Preferably, the antibacterial enzyme is glucose oxidase, pyranose oxidase, hexose oxidase, galactose oxidase, cholesterol oxidase, xanthine oxidase, alcohol oxidase, aryl alcohol oxidase, vanillyl alcohol oxidase, veratrile Alcohol oxidase, NAD(P)H oxidase, gulonolactone oxidase, pyridoxine oxidase, hydroxy oxidase, choline oxidase, glycerol-3-phosphate oxidase, arabino-lactone oxidase, glyoxal oxidase , Aldehyde oxidase, oxalate oxidase, aryl aldehyde oxidase, L-amino acid oxidase, L-glutamate oxidase, polyamine oxidase, hydroxylamine oxidase, thiol oxidase, glutathione oxidase, cytochrome C oxidase, Alcohol dehydrogenase and cellobiose may include any one or more antimicrobial enzymes selected from the group consisting of dehydrogenase, may be, for example, glucose oxidase, and the glucose oxidase catalyzes glucose oxidation to produce hydrogen peroxide. , The produced hydrogen peroxide reacts with genetic material, proteins, lipids, etc. in living organisms and can induce the death of microorganisms.

The structure refers to an insoluble support capable of immobilizing an antibacterial enzyme. The material of the structure has a normal support function and there is no restriction as long as it does not inhibit or inhibit the enzyme activity, and the shape is not particularly limited such as a bead, rod, fiber, or plate shape, but by using a plate shape, It is possible to provide an advantage of minimizing the increase in film resistance. In addition, it may have a structure such as porous, hollow, but is not limited thereto. In addition, as an example, the structure may include any one or more compounds selected from the group consisting of carbon, silica, aluminum, silver, gold, and polymers. In this case, the structure composed of the carbon may be at least one selected from the group consisting of carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, activated carbon, and graphite, for example, a thin film capable of minimizing the increase in film resistance It may be graphene having a high mechanical strength while having a thickness, graphene oxide, or reduced graphene oxide. In addition, the polymer compound is polyvinyl alcohol, polyacrylonitrile, nylon, polyester, polyurethane, polyvinyl chloride, polystyrene, cellulose, chitosan, polylactic acid, polylactic-co-glycolic acid, polyglycolic acid, poly It may be any one or more selected from the group consisting of caprolactone, collagen, polyaniline and poly(styrene-co-maleic anhydride).

The structure may be different in size depending on the shape. Here, the size of the structure means a diameter in the case of a spherical shape, and a maximum length of a line segment connecting two different points of a surface in the case of a non-spherical shape. In addition, in the case of the rod type, it means the length, and in the case of the plate type, it means the maximum length among the lengths of the line segments included in the upper surface or the lower surface. For example, bead, rod, plate, etc., except for the fiber, may have a structure size of 0.01 to 100 μm, more preferably 0.1 to 30 μm. If the size of the structure is less than 0.01 μm, as the tendency to aggregate between structures increases, the content of the antibacterial enzyme that can be introduced into one structure can be significantly reduced, and the aggregated structure closes the pores of the porous media to significantly reduce the flow rate. Can be reduced. In addition, due to the small size of the structure, the antimicrobial enzyme-structure complex may move through the pores of the porous media and be fixed to the inner surface or the lower surface of the porous media in the lower direction. In this case, even if a material capable of killing microorganisms is generated from the antibacterial enzyme-structure complex fixed to the inner surface or the lower surface of the porous media, the material reaches the upper surface of the porous media when considering the flow of raw water in the porous media. Since it cannot, the material may be difficult to exist at a concentration sufficient to kill microorganisms in the vicinity of the upper surface of the porous media, and thus, there is a possibility that the antibacterial activity is greatly reduced. In addition, if the size of the structure exceeds 100 μm, the structure may easily leak from the porous media into the solution phase and leak due to changes in the external environment such as agitation, and the structure may close the pores of the porous media to significantly reduce the flow rate. The content of antimicrobial enzymes that can be reduced or introduced into porous media can be significantly reduced.

As a specific example, when the structure is a rod type such as a carbon nanotube, the length may be 0.1 μm to 10 μm, and the diameter corresponding to the width may be 0.5 nm to 100 nm. Meanwhile, when the structure is fibrous, the length may be 0.1 μm or more, and the diameter may be 10 nm to 10 μm, but is not limited thereto.

Next, the polydopamine coating layer formed on the surface of the porous media will be described. The polydopamine coating layer is for introducing and fixing the above-described antimicrobial enzyme-structure complex to the porous media, and there is no separate functional group for fixing the antimicrobial enzyme-structure complex to the porous media, or the porous media has strong hydrophobicity and antibacterial enzyme- Even if it does not easily get wet with the solution containing the structure, there is an advantage that it can be easily introduced and fixed to the porous media. Here, the surface of the porous media includes an outer surface of the porous media and an inner surface corresponding to the pore walls existing inside the porous media.

The above-described antimicrobial enzyme-structure complex is fixed to the surface of the porous media through a polydopamine coating layer, and may be fixed to part or all of the surface. In addition, it can be fixed to all or part of the inner surface, including the outer surface of the porous media. On the other hand, in order to have an antimicrobial activity capable of killing microorganisms to the extent that the membrane for water treatment prevents or minimizes the formation of a biofilm, it is preferable that a substance having antibacterial activity is concentrated on the surface of the membrane. Accordingly, according to a preferred embodiment of the present invention, the antimicrobial enzyme-structure complex may be provided to be fixed to the outer surface portion of either side of the porous media. Here, the outer surface part means a region from the surface of one surface of the porous media to a thickness point that is 1/4 of the total thickness in the thickness direction. There may be a number of methods in which the antimicrobial enzyme-structure complex is concentrated on any one surface portion of the porous media, but as an example, the size of the structure in the antimicrobial enzyme-structure complex can be adjusted to be larger than the average pore size of the porous media. . On the other hand, when the complex is concentrated on one surface portion, it may be evenly fixed to the front surface of one surface, or may be partially fixed in part.

The amount of the antimicrobial enzyme-structure complex fixed on the porous media is preferably provided at a level that simultaneously expresses the antibacterial effect without increasing the water permeation resistance of the porous media. The content of the antimicrobial enzyme fixed to the porous media-structure complex is difficult to uniformly limit the content as the density varies depending on the material of the structure and the internal structure (porosity, etc.), but preferably the antimicrobial enzyme per unit area (㎡) It may be included in a content of 0.004 ~ 14g / ㎡ per unit area of the membrane based on the structure content of the structure complex. For example, when the structure is graphene oxide, per membrane unit area, it may be provided in an amount of 0.04 to 1.4 g/m 2, more preferably 0.08 to 1.0 g/m 2. If the antibacterial enzyme-structure complex is provided in an amount of less than 0.004 g/m 2 based on the structure content, the antibacterial performance may be significantly reduced. In addition, if the antibacterial enzyme-structure complex is provided in excess of 14 g/m 2 based on the structure content, the improvement in antimicrobial performance is negligible, while the permeation resistance is significantly increased, so that the desired flow rate may not be secured.

Hereinafter, a method for preparing a membrane for water treatment having antibacterial activity according to the present invention will be described. As shown in Figure 2, the membrane for water treatment having antibacterial activity according to an embodiment of the present invention includes (1) forming a polydopamine coating layer by treating a dopamine solution on a porous media and (2) a polydopamine coating layer. It may be prepared by treating the solution containing the antimicrobial enzyme-structure complex on the formed porous media to fix the antimicrobial enzyme-structure complex to the polydopamine coating layer.

First, step (1) according to the present invention is a step of forming a polydopamine coating layer on the surface of the porous media.

The dopamine solution is a solution containing dopamine or a salt thereof, and the solvent may include one or more selected from any solution group capable of maintaining pH, such as a phosphate buffer solution and a Tris buffer solution. The dopamine solution may include dopamine or a salt thereof at 0.1 to 5 mg/ml, and if dopamine or a salt thereof is provided at less than 0.1 mg/ml, the immobilized antimicrobial enzyme-structure complex is not immobilized to a desired level. It may not be possible, and there is a fear of being detached from the repeated water treatment process even when it is fixed. In addition, the dopamine solution may further include an initiator for polymerizing dopamine. The initiator may be used without limitation in the case of a known initiator for polymerizing dopamine, and may be, for example, sodium periodate (NaIO ₄ ). The method in which the dopamine solution or initiator is treated on the porous media may be used without limitation in the case of a known coating method, and may be, for example, impregnation, screen printing, comma coater, and the like. In addition, the formation of the polydopamine coating layer can be performed under conditions of pH 7.0 to 8.0.

After the dopamine solution is processed, it may be left at room temperature for 10 minutes or more, for example, 10 to 60 minutes to form a polydopamine coating layer, but is not limited thereto.

On the other hand, in FIG. 2, the polydopamine coating layer is shown to be formed only on the upper surface of the PVDF porous media, but it is revealed that the polydopamine coating layer may be formed on the inner and lower surfaces of the porous media.

Next, as a step (2) according to the present invention, a solution containing an antimicrobial enzyme-structure complex is treated on a porous media having a polydopamine coating layer to fix the antimicrobial enzyme-structure complex to the polydopamine coating layer.

The antibacterial enzyme-structure complex may be prepared through the process of FIG. 1 by way of example. Hereinafter, the structure will be described by exemplifying graphene oxide (GRO) and antibacterial enzyme as glucose oxidase (GOx).

First, in the case of a complex in the form of two-dimensionally fixed antibacterial enzyme GOx on the GRO surface, it can be obtained by mixing and stirring GRO and GOx. At this time, mixing of the two materials may be performed in a phosphate buffer solution having a pH of 5.5 to 8.0. Through this, it is possible to obtain a complex (EA) in which GOx is two-dimensionally adsorbed on the GRO surface. Meanwhile, after stirring, a washing process for removing GOx that is not attached to the GRO may be performed once to several times.

Next, as a case of producing a complex in the form of three-dimensionally fixed antibacterial enzyme GOx on the surface of the GRO, first, a crosslinking agent is used to form a complex (EAC) in which the GOx forms a crosslinker to surround the GRO. When the method is described, an EAC complex can be obtained by adding a crosslinking agent, for example, a glutaraldehyde solution, after mixing and stirring the two materials during the above-described EA complex manufacturing process. Even in this case, a washing process for removing GOx that is not fixed to the GRO or does not form a crosslinked product may be performed once to several times.

In addition, a method for preparing a complex (EAPC) in the form of surrounding a GRO by forming a crosslinked body by using a precipitating agent and a crosslinking agent is a precipitating agent, for example, after mixing and stirring two materials during the above-described EA complex manufacturing process. After adding ammonium sulfate solution and mixing for 10 to 60 minutes, it can be obtained by adding a crosslinking agent, for example, a glutaraldehyde solution. Even in this case, a washing process for removing acylase not attached to CNTs may be performed once to several times. Even in this case, a washing process for removing GOx that is not fixed to the GRO or does not form a crosslinked product may be performed once to several times.

The antibacterial enzyme-structure complex obtained through this (EAC, EAPC) can be stored in a storage solution, for example, a phosphate buffer solution or a Tris buffer solution, and a polydopamine coating layer prepared through step (1) in a solution state contained in the storage solution It can be treated on top of the provided porous media. At this time, the treatment may be a conventional coating method as described above.

According to a preferred embodiment of the present invention, the step (2) may be carried out under reduced pressure filtration so that the flow of the solution containing the antimicrobial enzyme-structure complex is formed from the top to the bottom of the porous media on which the polydopamine coating layer is formed. And, the vacuum filtration process may be, for example, vacuum filtration. If the vacuum filtration process is not performed, it may not be introduced into the porous media at a high content even when the concentration of the antimicrobial enzyme-structure complex contained in the solution is high. However, there is an advantage that the antimicrobial enzyme-structure complex contained in the solution can be introduced on the porous media in a sufficient amount by performing the vacuum filtration process.

After vacuum filtration, an aging step for binding the antimicrobial enzyme-structure complex to the polydopamine coating layer may be further performed. The aging step may be performed at room temperature, for example, at 25° C. for 10 minutes or more, but is not limited thereto.

After vacuum filtration, a step for inactivating the polydopamine coating layer to which the antibacterial enzyme-structure complex is not bound may be further performed. At this time, Tris buffer solution may be used to inactivate polydopamine, but is not limited thereto.

The membrane for water treatment having antibacterial activity implemented through the above-described manufacturing method may be implemented as a water treatment module. The water treatment module is equipped with a membrane for water treatment, a housing provided with an internal space for receiving raw water, various conduits for introducing raw water to one side of the housing, a valve, and filtrate filtered to the other side of the housing Various conduits and valves capable of discharging may further include various parts included in a known water treatment module. These parts may have known shapes, sizes and functions, and the present invention is not particularly limited.

Hereinafter, the present invention will be described in detail through examples. However, the scope of the present invention is not limited by the present embodiment.

<Preparation Example 1>-Preparation of a complex with two-dimensionally fixed antibacterial enzyme (EA complex)

After mixing the graphene oxide (GROs) solution (1 mg/mL) and glucose oxidase (GOx) solution (10 mg/mL) prepared in phosphate buffer (100 mM pH 7.0) in a 2 to 1 volume ratio, It was stirred at 200 rpm for 1 hour. Through this process, glucose oxidase was adsorbed on the surface of graphene oxide. Thereafter, GOx not attached to the graphene oxide was removed, and the unreacted functional group was capped by stirring at 200 rpm for 30 minutes with Tris buffer. After centrifugation, the supernatant was removed, washed with phosphate buffer, and stored at 4°C.

<Preparation Example 2>-Preparation of a complex with a three-dimensionally fixed antibacterial enzyme on the structure as a crosslinking agent (EAC complex)

After mixing the graphene oxide (GROs) solution (1 mg/mL) and glucose oxidase (GOx) solution (10 mg/mL) prepared in phosphate buffer (100 mM pH 7.0) in a 2 to 1 volume ratio, It was stirred at 200 rpm for 1 hour. Through this process, an EA complex in which glucose oxidase was adsorbed on the surface of graphene oxide was prepared. Then glutaraldehyde solution was added to a final concentration of 0.5% (w/v). Then, the mixture was stirred at 50° C. for 12 hours at 4° C. for sufficient crosslinking. Thereafter, the unreacted aldehyde group was capped by stirring at 200 rpm for 30 minutes with Tris buffer. After centrifugation, the supernatant was removed, washed with phosphate buffer, and stored at 4°C.

<Preparation Example 3>-Preparation of a complex with an antibacterial enzyme three-dimensionally immobilized on a structure with a precipitating agent and a crosslinking agent (EAPC complex)

After mixing the graphene oxide (GROs) solution (1 mg/mL) and glucose oxidase (GOx) solution (10 mg/mL) prepared in phosphate buffer (100 mM pH 7.0) in a 2 to 1 volume ratio, It was stirred at 200 rpm for 1 hour. Through this process, an EA complex in which glucose oxidase was adsorbed on the surface of graphene oxide was prepared. Thereafter, the ammonium sulfate solution was added at a final concentration of 0.5 g/ml and mixed for 30 minutes, and then the glutaraldehyde solution was added to a final concentration of 0.5% w/v%. Then, it was stirred at 50 rpm for 12 hours at 4°C to sufficiently crosslink. Thereafter, the unreacted aldehyde group was capped by stirring at 200 rpm for 30 minutes with Tris buffer. After centrifugation, the supernatant was removed, washed with phosphate buffer, and stored at 4°C.

<Preparation Examples 4 to 8>-EAPC complex prepared by varying the concentration of precipitating agent

Prepared in the same manner as in Preparation Example 3, the concentration of the precipitating agent was changed as shown in Table 1 to prepare an EAPC complex.

Preparation Example 4 Preparation Example 5 Preparation Example 6 Preparation Example 7 Preparation Example 8 Precipitation agent concentration 0.1 g/ml 0.2 g/ml 0.3 g/ml 0.4 g/ml 0.6 g/ml

<Example 1>-Antimicrobial enzyme-structure complex (EAPC complex) A fixed membrane (EAPC membrane) has an average pore size of 0.45 μm, a thickness of 100 μm, and a PVDF porous media having a basis weight of 70 g/m 2 was prepared. Subsequently, a dopamine solution containing dopamine hydrochloride having a concentration of 2 mg/ml and sodium periodate (NaIO ₄ ) having a concentration of 1 mg/ml was applied to the PVDF porous media, and then allowed to stand at 25° C. for 30 minutes for polydopamine ( A polydopamine (pDA) coating layer was formed. The uncoated dopamine components were removed by washing with phosphate buffer. Subsequently, the phosphate buffer solution containing the EAPC complex prepared in Preparation Example 3 was uniformly applied to the top of the porous media having a polydopamine coating layer formed by vacuum filtration, and then immersed in a phosphate buffer solution (100 mM, pH 7.5) for 1 hour. The binding of the polydopamine coating layer and the antibacterial enzyme-structure complex (EAPC complex) was induced. At this time, the amount of the EAPC composite applied was treated such that the EAPC composite was fixed at a content of 0.1 g/m 2 per unit area of membrane based on the weight of GRO, and then treated with Tris buffer solution to cap the unreacted functional groups to prevent antibacterial activity. A membrane having a membrane was prepared.

<Examples 2 to 6>-EAPC membrane with different EAPC complex content

Prepared in the same manner as in Example 1, but the amount of the EAPC complex prepared in the phosphate buffer is different, and the EAPC complex is 0.02 g/m 2 per membrane unit area based on the weight of GRO (Example 2) and 0.04 g/m 2 (Example 3), fixed at contents of 0.06 g/m 2 (Example 4), 0.08 g/m 2 (Example 5), 0.14 g/m 2 (Example 6), and 0.20 g/m 2 (Example 7) A membrane with antibacterial activity was prepared.

<Comparative Example 1>-PVDF membrane

The PVDF porous media used in Example 1 without any treatment such as polydopamine coating and antimicrobial enzyme-structure complex fixation was prepared as a membrane for water treatment.

<Comparative Example 2>-PVDF membrane formed with polydopamine coating layer

Prepared in the same manner as in Example 1, but formed only a polydopamine coating layer, to prepare a membrane for water treatment without fixing the antimicrobial enzyme-structure complex.

<Experimental Example 1> Measurement of enzyme activity of antibacterial enzyme-structure complex

Glucose oxidase (GOx) exerts antibacterial activity by damaging the plasma membrane of bacteria. The antimicrobial activity of the antimicrobial enzyme-structure complexes according to Preparation Examples 1 to 8 was measured using absorbance that hydrogen peroxide produced by hydrolysis of glucose reacts with TMB under perradase (horseradish peroxidase, HRP). As shown in Figure 4 and Table 1 below, the initial enzymatic activity of the EA complex of Preparation Example 1 and the EAC complex of Preparation Example 2 can be confirmed to have significantly lower antibacterial activity compared to the EAPC complex of Preparation Examples 3 to 8.

Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Preparation Example 6 Preparation Example 7 Preparation Example 8 Initial enzyme activity (unit/min/mg-GRO) 0.034 0.044 168 15 11 106 138 139

<Experimental Example 2>-Membrane antibacterial performance evaluation 1 Fig. 4 is a schematic diagram showing a method for evaluating the antibacterial performance of a membrane. After attaching the model bacteria Pseudomonas aeruginosa ( P.aeruginosa ) to the membrane filtration surface according to Example 1 and Comparative Example 1, the cells were cultured on synthetic sewage medium to induce cell proliferation. After incubation for 6 hours, SYTO® 9 and propidium iodide (PI) staining were performed, and confocal laser scanning microscopy (CLSM) was used to confirm the plasma membrane damage of P.aeruginosa bacteria.

5 and 6 are images obtained by observing the activity of P.aeruginosa bacteria attached to the membrane surface after CL culture for 6 hours with CLSM. The active cells (live cells) are stained with SYTO® 9 to show green fluorescence. On the other hand, damaged cells of the cell plasma membrane are stained with PI and show red fluorescence. As the number of bacteria showing red fluorescence on the surface of the EAPC membrane is increased compared to the PVDF membrane, it is possible to confirm the outstanding antibacterial properties of the EAPC membrane. In particular, as can be seen in Figure 6, the thickness of the biofilm produced on the surface of the membrane (PVDF) according to Comparative Example 1 was about 9.4 times the thickness of the biofilm produced on the surface of the membrane (EAPC(0.1)) according to Example 1, and the comparative example While the biofilm formed on the membrane according to 1 was dense and mature, the biofilm formed on the membrane according to Example 1 was observed with a coarse structured biofilm, and thus it was confirmed that the formation of the biofilm due to bacterial plasma membrane damage was suppressed.

<Experiment 3>-Membrane antibacterial performance evaluation 2

7 is another method for evaluating the antibacterial activity of a membrane, and is a schematic diagram showing a method and apparatus for evaluating the antimicrobial performance of a membrane through trans-membrane pressure (TMP) in constant flux operation.

After mounting the membrane in the apparatus shown in FIG. 7, the inter-membrane pressure difference (TMP) was measured under 20 L/m 2 /h constant flow operation conditions. Specifically, the TMP value measured on the PVDF membrane which is not antibacterially treated is compared with the baseline, and the lower the TMP measured on the antibacterial membrane, the better the membrane antibacterial performance.

* Experimental Example 3-1 (model bacteria Pseudomonas aeruginosa use)

After attaching the model bacteria Pseudomonas aeruginosa ( P.aeruginosa ) to the membranes according to Comparative Example 1 (PVDF membrane), Examples 1 to 3 through the method of FIG. 4, the cells were cultured for 6 hours on a synthetic sewage medium to proliferate. It is driving, the biofilm was equipped with a preformed membrane to the device of Figure 7, showing the results of TMP on the membrane is due to P.aeruginosa biofilms formed in Fig.

As can be seen through Figure 8, the membrane according to Comparative Example 1, the inter-membrane differential pressure reached 5 kPa after 10 hours elapsed, but the membranes according to Example 1 and Example 3 had an inter-membrane differential pressure of 5 kPa after 65 hours and 30 hours, respectively. It can be seen that the antimicrobial activity is very excellent through reaching, and the differential pressure generation due to the biofilm is minimized even after a long operation.

* Experimental Example 3-2 (model bacteria Staphylococcus aureus use )

After attaching the model bacteria Staphylococcus aureus (S.aureus) , which is a Gram-positive bacteria, to the membranes according to Comparative Example 1 (PVDF membrane) and Example 1 (EAPC membrane) through the method of FIG. 4, incubate for 6 hours on a synthetic sewage medium. The membrane in which the biofilm, which induced cell proliferation, was already formed, was mounted on the apparatus of FIG. 7, and the TMP result according to the membrane on which the biofilm was formed by S. aureus is shown in FIG.

As can be seen through FIG. 9, after 17 hours of continuous filtration, the TMP of the PVDF membrane of Comparative Example 1 reached 30 kPa, whereas the TMP of the EAPC membrane was 0.5 kPa, which was minimal compared to the initial stage of operation, resulting in remarkably excellent antibacterial activity. It can be confirmed that it is expressed.

<Experiment 4>-Membrane water permeability evaluation

For the membranes according to Comparative Example 1 and Examples 1 to 6, water permeability was measured by the following methods, and the results are shown in Table 3 and FIG. 10 below.

In this case, trans-membrane pressure (TMP) in constant flux operation under various flow conditions was measured, and a change in the inter-membrane pressure according to the flow was measured to derive a water permeation resistance value. Specifically, the membrane for water treatment according to Comparative Examples and Examples was mounted on a water treatment module and filled with distilled water, TMP was measured while changing the flow rate through a pump, and water permeability resistance was calculated by the following equation.

[expression]

Where R _m = water permeability resistance, ΔP = TMP, μ: viscosity of distilled water = 1, Flux: flow rate)

Based on the PVDF membrane according to Comparative Example 1, it can be evaluated that the less the increase in the water permeability resistance measured, the less the water permeability due to the antimicrobial enzyme-structure complex introduced in the porous media.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Fixed EAPC content
(g/㎡) 0.1 0.02 0.04 0.06 0.08 0.14 0.20 0 Water permeation resistance (×10 ¹⁰ m ^-1 ) 1.37 1.18 1.12 1.42 1.34 1.57 6.07 1.18

* The fixed EAPC content is based on the GRO weight. Specifically, as can be seen through Table 3 and FIG. 10, when compared with the PVDF membrane according to Comparative Example 1, the antimicrobial enzyme-structure complex was introduced into the water permeable even when introduced into the porous media. It can be seen that the resulting increase in resistance is small. However, in the case of Example 7 in which the content of the antibacterial enzyme-structure complex was excessive, it was confirmed that the water permeation resistance increased compared to Example 6.

<Experiment 5>-Membrane surface observation

For the membranes for water treatment according to Comparative Examples 1 to 2 and Examples 1 to 5, a surface photograph of the upper surface of the membrane was taken through a scanning electron microscope, and the results are shown in FIG. 10.

As can be seen through Figure 10, it can be seen that the antimicrobial enzyme-structure complex is introduced and fixed on the surface of the membrane for water treatment according to Examples 1 to 5 when compared with the membranes according to Comparative Examples 1 to 2.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art to understand the spirit of the present invention can add elements within the scope of the same spirit. However, other embodiments may be easily proposed by changing, deleting, adding, or the like, but it will also be considered to be within the scope of the present invention.

Claims (13)

Porous media;
A polydopamine coating layer coated on at least a portion of the surface of the porous media; And
An antimicrobial enzyme-structure complex fixed to the porous media through the polydopamine coating layer; According to claim 1,
The porous media is a membrane for water treatment having an antibacterial activity, characterized in that the average pore size is 0.1 nm ~ 10 ㎛. According to claim 1,
The porous media is polyvinylidene fluoride, polyvinylalcohol, polyvinylacetate, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrroli Money (polyvinylpyrrolidone), polytetrafluoroethylene, polyimide, polyethylene oxide, polysulfone, poly ether sulfone, cellulose acetate, cellulose Acetate butylate (cellulose acetate butyrate), cellulose acetate propionate, aluminum oxide (Al ₂ O ₃ ), silicon carbide, silicon nitride, zirconium oxide (ZrO ₂ ) and oxidation A membrane for water treatment having antibacterial activity, characterized in that it is formed of at least one compound selected from the group consisting of titanium (TiO ₂ ). According to claim 1,
The antimicrobial enzyme-structure complex is a membrane for water treatment having antibacterial activity, characterized in that the antimicrobial enzyme is immobilized on the surface or inside of the structure. According to claim 1,
The structure is one selected from the group consisting of carbon nanotubes, graphene, graphene oxide, activated carbon, polymer nanofibers, nanoporous particles, silica particles, aluminum particles, silver nanoparticles, gold nanoparticles, magnetic nanoparticles, and zeolites. Membrane for water treatment having an antibacterial activity, characterized in that it contains the above. According to claim 1,
The antimicrobial enzyme-structure complex is a membrane for water treatment having antibacterial activity, characterized in that provided to be fixed to the outer surface portion of either side of the porous media. According to claim 1,
The antibacterial enzymes include glucose oxidase, pyranose oxidase, hexose oxidase, galactose oxidase, cholesterol oxidase, xanthine oxidase, alcohol oxidase, aryl alcohol oxidase, vanyl alcohol oxidase, veratril alcohol oxidase , NAD(P)H oxidase, gulonolactone oxidase, pyridoxine oxidase, hydroxy oxidase, choline oxidase, glycerol-3-phosphate oxidase, arabino-lactone oxidase, glyoxal oxidase, aldehyde oxidation Enzyme, oxalate oxidase, aryl aldehyde oxidase, L-amino acid oxidase, L-glutamate oxidase, polyamine oxidase, hydroxylamine oxidase, thiol oxidase, glutathione oxidase, cytochrome C oxidase, alcohol dehydrogenase And Cellobiose dehydrogenase membrane for water treatment having an antibacterial activity, characterized in that it comprises at least one antibacterial enzyme selected from the group consisting of. According to claim 1,
A membrane for water treatment having antibacterial activity, characterized in that the structure of the antimicrobial enzyme-structure complex per unit area (㎡) is provided in an amount of 0.004 to 14 g. According to claim 4,
The antimicrobial enzyme-structure complex is a membrane for water treatment having antimicrobial activity, characterized in that the antimicrobial enzymes are cross-linked. According to claim 4,
The antimicrobial enzyme-structure complex is a membrane for water treatment having antibacterial activity, characterized in that the antimicrobial enzymes precipitated through a precipitating agent are crosslinked. (1) forming a polydopamine coating layer by treating the dopamine solution on the porous media; And
(2) fixing the antimicrobial enzyme-structure complex to the polydopamine coating layer by treating a solution containing an antimicrobial enzyme-structure complex on a porous media having a polydopamine coating layer formed thereon; a method for manufacturing a membrane for water treatment having antibacterial activity comprising . The method of claim 11,
The (2) step is a method for producing a membrane for water treatment with antibacterial activity, characterized in that it comprises a pressure-reduction filtration process in which the solution is formed so that a flow through the porous media having a polydopamine coating layer is formed in one direction. A water treatment module comprising a membrane for water treatment having antibacterial activity according to any one of claims 1 to 10.

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