JP2017036191A - Graphene derivative and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material high in protein adsorption performance.SOLUTION: A graphene derivative has present amount of a component derived from O=C-O bond of 8 to 20% based on the total of present amounts of a component derived from C-C bond, a component derived from C=C bond, a component derived from C-O bond, a component derived from C-O-C bond, and the component derived from C=O-C bond, calculated with a wave shape separation of C1s spectrum measured by an X-ray photoelectron spectroscopy.SELECTED DRAWING: None

Description

  Embodiments described herein relate generally to a graphene derivative and use thereof.

  By modifying lysozyme, an antibacterial enzyme, on the surface of the reverse osmosis membrane and imparting antibacterial properties to the reverse osmosis membrane, fouling of the reverse osmosis membrane due to the propagation of various bacteria is suppressed and the water permeability of the reverse osmosis membrane is improved Technology is known.

Special table 2008-538531 gazette JP 2012-211043 A JP 2002-126510 A JP 2007-22873 A

  However, binding of lysozyme to the reverse osmosis membrane surface by the conventional method requires multi-step synthesis and is complicated. For this reason, a material capable of easily fixing a protein such as lysozyme has been demanded. The problem to be solved by the present invention is to provide a material having a high protein adsorption capacity.

  The graphene derivative of the embodiment includes a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—, calculated by waveform separation of C1s spectrum measured by X-ray photoelectron spectroscopy. The abundance of the component derived from the O═C—O bond is 8 to 20% with respect to the total amount of the component derived from the O—C bond and the component derived from the O═C—O bond.

The graph which shows the result of Experimental example 1. FIG. The graph which shows the result of Experimental example 2. The schematic diagram which shows the water treatment system of embodiment.

  A graphene derivative obtained by oxidizing a graphene surface has a functional group such as a hydroxyl group or a carboxyl group on the surface, and properties such as composition, hydrophobicity, and electrical conductivity are completely different from graphene. In addition, the properties of graphene derivatives vary depending on the raw material graphite and reaction conditions. Since graphene derivatives are non-toxic and biodegradable, their application to water treatment materials has recently begun to be studied.

  The inventors have found that specific graphene derivatives have high protein adsorption ability. Hereinafter, the graphene derivative of the embodiment will be described.

  The graphene derivative of this embodiment is a component derived from a C—C bond, a component derived from a C═C bond, a component derived from a C—O bond, C, calculated by waveform separation of a C1s spectrum measured by X-ray photoelectron spectroscopy. The abundance of the component derived from the O═C—O bond is 8 to 20% with respect to the sum of the abundance of the component derived from the —O—C bond and the component derived from the O═C—O bond. In the present specification, a component derived from a C—O—C bond means a component derived from a bond contained in an epoxy group.

  As shown in the examples described later, the graphene derivative of the present embodiment has a high protein adsorption ability. Therefore, it can also be said that the graphene derivative of this embodiment is a protein adsorbent.

  Here, the waveform separation is to decompose the entire waveform of the C1s spectrum measured by X-ray photoelectron spectroscopy (XPS) into the sum of component waveforms. As the component waveform, a Gaussian function, a Lorentz function, a Gauss / Lorentz mixed function, or the like is generally used.

  More specifically, the entire waveform of the C1s spectrum of the graphene derivative is represented by a component derived from a C—C bond, a component derived from a C═C bond, a component derived from a C—O bond, a component derived from a C—O—C bond, and By separating each component waveform of components derived from O = C—O bond, the abundance (relative value) of each component can be obtained.

  In the graphene derivative of this embodiment, a component derived from a C—C bond, a component derived from a C═C bond, a component derived from a C—O bond, a component derived from a C—O—C bond, and a component derived from an O═C—O bond 12-20% may be sufficient as the abundance of the component derived from an O = CO bond with respect to the total of the abundance of the component, and 14-20% may be sufficient as it.

  The graphene derivative of the present embodiment may have a hydroxyl group, an epoxy group, or the like in addition to a component derived from an O═C—O bond, that is, a carboxyl group. Moreover, the carboxyl group and hydroxyl group contained in the graphene derivative of this embodiment may form a salt. Examples of the salt include sodium salt, potassium salt, calcium salt, magnesium salt and the like.

  In the graphene derivative of the present embodiment, the atomic ratio (O / C) of oxygen to carbon may be, for example, 50 to 90%, for example, 52 to 90%, for example, 54 to 90%. There may be. The atomic ratio (O / C) between oxygen and carbon can be measured, for example, by X-ray photoelectron spectroscopy.

  As shown in Examples described later, graphene derivatives having an oxygen to carbon atomic ratio (O / C) in the above range tend to have a high protein adsorption capacity.

  The graphene derivative of the present embodiment can be produced by the Hammers method known as a graphene oxide synthesis method. More specifically, for example, 96% sulfuric acid is cooled to about 4 ° C. while stirring with a mechanical stirrer, sodium nitrate is added, and small piece graphite is further added. Subsequently, potassium permanganate is gradually added. Subsequently, the mixture is stirred for about 3.5 hours in a room temperature water bath. Subsequently, water is added while cooling in a water bath. Subsequently, it is heated in an oil bath set at about 130 ° C. for about 1 hour. Subsequently, a liquid obtained by mixing 35% hydrogen peroxide water and water is dropped, and the mixture is further stirred for about 10 minutes. The obtained suspension is centrifuged and the supernatant liquid is fractionated. A graphene derivative can be produced by washing the collected precipitate with 1N hydrochloric acid and vacuum drying at room temperature.

  By adjusting the amount of oxidant and the reaction time between graphite and oxidant, the oxygen to carbon atomic ratio (O / C) of the graphene derivative, and the component derived from C—C bond, C═C bond derived The abundance of components derived from O = C—O bonds with respect to the sum of the abundance of components, components derived from C—O bonds, components derived from C—O—C bonds, and components derived from O═C—O bonds. Can be adjusted.

Then, the composite_body | complex of embodiment is demonstrated.
The complex of this embodiment is a complex of the graphene derivative described above and an antibacterial protein or derivative thereof.

  The composite of this embodiment can be easily formed by adding the graphene derivative described above to an aqueous solution containing an antibacterial protein or a derivative thereof and stirring the mixture with a mix rotor or the like for 1 to 24 hours. The formed complex may be collected by filtration or centrifugation. After the collection, for example, it may be washed with pure water and air dried or vacuum dried at about 40 ° C.

  In the complex of this embodiment, examples of the antibacterial protein include lysozyme, defensin, puroindoline, thionine, lactoferrin, and apriocyanin A.

  Examples of the antibacterial protein derivatives include those having antibacterial properties among the above-mentioned protein fragments and the above-mentioned protein mutants.

  These antibacterial proteins or derivatives thereof can be used alone or in combination of two or more.

Subsequently, the fiber of the embodiment will be described.
The fiber of this embodiment contains the composite body of the said embodiment. For this reason, the fiber of this embodiment can exhibit antibacterial properties.

  The fiber of this embodiment can be manufactured by adding the composite of the said embodiment to the material of a fiber similarly to a filler in the manufacturing process.

  Examples of the fiber material include materials that can be processed at a low temperature that does not impair the function of the protein. More specifically, from the viewpoint of enabling dry spinning, wet spinning, or electrospinning, acetate resin, acrylic resin, vinylon, polyvinylidene fluoride (PVDF) resin, polytetrafluoroethylene (PTFE) resin, polyethersulfone (PES) ) Resins and the like.

  What is necessary is just to adjust the addition amount of a composite_body | complex by the kind of protein which comprises a composite_body | complex, the use of a fiber, etc. The amount of the composite added may be, for example, about 0.1 to 10% by mass with respect to the weight of the fiber product. If it is the said range, the effect of the protein which comprises the said composite_body | complex can be acquired, and the intensity | strength etc. of a product will not be affected.

Then, the filter medium of embodiment is demonstrated.
The filter medium of this embodiment contains the composite body of the said embodiment. For this reason, the filter medium of this embodiment can exhibit antibacterial properties.

  The filter medium of this embodiment can be manufactured by adding the composite of the said embodiment to the material of a filter medium similarly to a filler in the manufacturing process. What is necessary is just to adjust the addition amount of the composite_body | complex with respect to the material of a filter medium with the kind of protein which comprises a composite_body | complex, the use of a filter medium, etc. The addition amount of a composite_body | complex may be about 0.1-10 mass% with respect to the weight of a filter material product, for example. If it is the said range, the effect of the protein which comprises the said composite_body | complex can be acquired, and the intensity | strength etc. of a product will not be affected.

  Examples of the material for the filter medium include the same materials as the fiber materials described above. Moreover, the filter medium may be composed of the above-described fibers, for example. Specifically, a woven fabric or a non-woven fabric made of the above-described fibers can be used. Alternatively, the filter medium may be a membrane, for example, a filter carrier. The membrane may be in the form of, for example, a flat membrane or a hollow fiber membrane, or may be a microfiltration membrane, an ultrafiltration membrane, a reverse osmosis membrane, or the like.

Subsequently, the adsorbent of the embodiment will be described.
The adsorbent of this embodiment contains the composite of the said embodiment. For this reason, the ion exchange resin of this embodiment can exhibit antibacterial properties.

  The adsorbent is a member having a strong property of adsorbing other substances on the surface, and examples thereof include those formed from materials such as activated carbon, activated alumina, and silica gel. The adsorbent can be used for decolorization, deodorization and the like.

  The adsorbent of this embodiment can be manufactured by adding the composite of the said embodiment to material in a granulation process.

Then, the ion exchange resin of embodiment is demonstrated.
The ion exchange resin of this embodiment contains the composite body of the said embodiment. For this reason, the ion exchange resin of this embodiment can exhibit antibacterial properties.

  The ion exchange resin is a kind of synthetic resin having a structure that ionizes as part of a molecular structure as an ionic group, and exhibits an ion exchange action with ions in a solvent such as water. It does not restrict | limit especially as an ion exchange resin of this embodiment, A general thing can be used.

  The ion exchange resin of this embodiment can be manufactured by adding the composite of the said embodiment to material in a granulation process.

Then, the water treatment system of embodiment is demonstrated with reference to drawings.
The water treatment system of this embodiment has the above-described filter medium, adsorbent, or ion exchange resin.

  Drawing 3 is a mimetic diagram showing the water treatment system of an embodiment. The water treatment system 100 includes a treated water inflow pipe 10, a water treatment unit 20, and a treated water outflow pipe 30. The water treatment unit 20 accommodates, for example, fibers, adsorbents, ion exchange resins, membranes, filtration carriers, and the like. At least some of the fibers, the adsorbent, the ion exchange resin, the membrane, the filtration carrier, and the like housed in the water treatment unit 20 are composed of the above-described filter medium, adsorbent, or ion exchange resin.

  The water treatment system 100 of this embodiment may be a seawater desalination system, a reverse osmosis water production system, or the like, for example.

Then, the water treatment method of embodiment is demonstrated, referring FIG.
The water treatment method of this embodiment treats water with the water treatment system described above. First, the water to be treated is introduced into the water treatment unit 20 inside the water treatment system 100 through the water to be treated inflow pipe 10.

  In the water treatment unit 20, the water to be treated is treated. Examples of the treatment in the water treatment unit 20 include microfiltration, ultrafiltration, nanofiltration, membrane filtration such as reverse osmosis, adsorption, ion exchange, and the like.

  Subsequently, the treated water treated by the water treatment unit 20 is discharged to the outside of the water treatment system 100 through the treated water outflow pipe 30 and sent to the next treatment facility as necessary.

  In the water treatment method of this embodiment, at least some of the fibers, adsorbents, ion exchange resins, membranes, filtration carriers and the like housed in the water treatment unit 20 are the above-mentioned filter media, adsorbents, or ion exchange resins. It consists of For this reason, according to the water treatment method using the water treatment system 100, propagation of various bacteria can be suppressed, and clogging (fouling) of the water treatment unit 20 can be suppressed.

[Example 1]
40 g of graphite (trade name “Z-5F”, manufactured by Ito Graphite), 1000 mL of concentrated sulfuric acid, and 30 g of sodium nitrate were mixed and cooled to 4 ° C. or lower. Subsequently, 150 g of potassium permanganate was gradually added while cooling, and the mixture was stirred at 6 ° C. or lower for 1 hour and at room temperature for 5 hours. Thereafter, the mixture was heated and refluxed for 10 minutes, and then cooled to room temperature. Subsequently, hydrogen peroxide was added and the resulting reaction product was filtered and washed thoroughly with dilute hydrochloric acid. Subsequently, the reaction product was dried with an air stream and then vacuum-dried at 60 ° C. to obtain 68 g of the graphene derivative of Example 1.

  The graphene derivative of Example 1 is a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—O—C, calculated by waveform separation of C1s spectrum measured by XPS. The abundance of the component derived from the O═C—O bond was 11% with respect to the total of the abundance of the component derived from the bond and the component derived from the O═C—O bond. The atomic ratio (O / C) was 52%.

[Example 2]
72 g of the graphene derivative of Example 2 was obtained in the same manner as Example 1 except that the reflux time was changed to 20 minutes.

  The graphene derivative of Example 2 is a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—O—C, calculated by waveform separation of C1s spectrum measured by XPS. The abundance of the component derived from the O═C—O bond was 14% with respect to the total of the abundance of the component derived from the bond and the component derived from the O═C—O bond. The atomic ratio (O / C) was 54%.

[Example 3]
70 g of the graphene derivative of Example 3 was obtained in the same manner as in Example 1 except that the stirring time at room temperature after the addition of potassium permanganate was changed to 6 hours and the reflux time was changed to 60 minutes.

  The graphene derivative of Example 3 is a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—O—C, calculated by waveform separation of C1s spectrum measured by XPS. The abundance of the component derived from the O═C—O bond was 14% with respect to the total of the abundance of the component derived from the bond and the component derived from the O═C—O bond. The atomic ratio (O / C) was 87%.

[Comparative Example 1]
50 g of graphite (trade name “Z-5F”, manufactured by Ito Graphite) and 150 g of potassium permanganate were mixed and stirred at 60 ° C. for 3 hours. The resulting reaction product was filtered and washed well with dilute hydrochloric acid. Subsequently, the reaction product was dried with an air stream and then vacuum-dried at 60 ° C. to obtain 60 g of a graphene derivative of Comparative Example 1.

  The graphene derivative of Comparative Example 1 is a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—O—C, calculated by waveform separation of C1s spectrum measured by XPS. The abundance of the component derived from the O═C—O bond was 2% with respect to the total of the abundance of the component derived from the bond and the component derived from the O═C—O bond. The atomic ratio (O / C) was 10%.

[Comparative Example 2]
50 g of graphite (trade name “Z-5F”, manufactured by Ito Graphite), 1000 mL of concentrated sulfuric acid, and 22 g of sodium nitrate were mixed and cooled to 4 ° C. or lower. Subsequently, 110 g of potassium permanganate was gradually added while cooling, and the mixture was stirred at 6 ° C. or lower for 1 hour and at room temperature for 4 hours. Thereafter, the mixture was heated and refluxed for 20 minutes, and then cooled to room temperature. Subsequently, hydrogen peroxide was added and the resulting reaction product was filtered and washed thoroughly with dilute hydrochloric acid. Subsequently, the reaction product was dried with an air stream and then vacuum-dried at 60 ° C., thereby obtaining 65 g of a graphene derivative of Comparative Example 2.

  The graphene derivative of Comparative Example 2 is a component derived from C—C bond, a component derived from C═C bond, a component derived from C—O bond, C—O—C, calculated by waveform separation of C1s spectrum measured by XPS. The abundance of the component derived from the O═C—O bond was 6% with respect to the total of the abundance of the component derived from the bond and the component derived from the O═C—O bond. The atomic ratio (O / C) was 30%.

[Experiment 1]
(Adsorption test)
Water to be treated containing 600 mg / L of protein (lysozyme) was prepared. The graphene derivatives of Examples 1 to 3 and Comparative Examples 1 to 2 and powdered activated carbon as a control were respectively added to 50 mL of the water to be treated, and stirred at 100 rpm for 3 hours with a mix rotor. A polypropylene centrifuge tube was used as the reaction vessel. Thereafter, 30 mL of each water to be treated was transferred to a polyethylene centrifuge tube for strong centrifugation, and centrifuged at 15,000 rpm for 5 minutes to separate the graphene derivative in the water to be treated.

  The protein concentration in each treated water was calculated from the absorption spectrum (280 nm) of each supernatant after centrifugation. Subsequently, the amount of protein adsorbed per 1 g of each graphene derivative or powdered activated carbon was determined from the difference from the initial concentration. The results are shown in FIG. Table 1 shows the XPS measurement results of the graphene derivatives used in the test.

[Experiment 2]
(Adsorption test)
An adsorption test was performed in the same manner as in Experimental Example 1 except that bovine serum albumin (BSA) was used instead of lysozyme as a protein. The results are shown in FIG. BSA adsorbed less than lysozyme. It has been reported that BSA has a significantly lower hydrophobicity based on amino acid sequence information than lysozyme, and it was speculated that such a difference in physical properties affects the amount of adsorption to graphene derivatives.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Treated water inflow pipe, 20 ... Water treatment unit, 30 ... Treated water outflow pipe, 100 ... Water treatment system.

Claims (12)

  Component derived from C—C bond, component derived from C═C bond, component derived from C—O bond, component derived from C—O—C bond, calculated by waveform separation of C1s spectrum measured by X-ray photoelectron spectroscopy And a graphene derivative in which the abundance of components derived from O = C—O bonds is 8 to 20% of the total abundance of components derived from O═C—O bonds.   The graphene derivative according to claim 1, wherein the atomic ratio (O / C) of oxygen to carbon is 50 to 90%.   A complex of the graphene derivative according to claim 1 or 2 and an antibacterial protein or a derivative thereof.   The complex according to claim 3, wherein the antibacterial protein is lysozyme, defensin, puroindoline, thionine, lactoferrin or apriocyanin A.   The fiber containing the composite_body | complex of Claim 3 or 4.   A filter medium containing the composite according to claim 3 or 4.   An adsorbent containing the complex according to claim 3 or 4.   An ion exchange resin containing the composite according to claim 3.   A water treatment system comprising the filter medium according to claim 6.   A water treatment system comprising the adsorbent according to claim 7.   A water treatment system comprising the ion exchange resin according to claim 8.   The water treatment method which processes water with the water treatment system as described in any one of Claims 9-11.

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