JP2023521043A - Filtration device comprising an antiviral filtration element and an antiviral filtration element - Google Patents

Abstract

A face mask is provided comprising (a) a mask body and (b) a fastener, the mask body comprising (i) an air permeable outer layer preferably comprising a hydrophobic material; (ii) an inner layer; ) a layer of graphene or graphene foam or graphite flakes disposed on the mask body, the graphene layer comprising a plurality of discrete single or few layers of graphene sheets, the graphene sheets comprising pristine graphene; selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitrogen, doped graphene, chemically functionalized graphene, or combinations thereof. A graphene or foam or graphite layer may be disposed in the mask body between the outer and inner layers, or may be embedded (wholly or partially) in the outer or inner layers. Graphene or foam pore walls or graphite flake surfaces may be deposited with antiviral or antimicrobial compounds. [Selection drawing] Fig. 2

Description

CROSS-REFERENCES TO RELATED APPLICATIONS This application is addressed to U.S. Patent Application Serial No. 16/839,827, filed April 3, 2020, U.S. Patent Application Serial No. 16/839,847, filed April 3, 2020. and U.S. Patent Application No. 16/844,062, filed April 9, 2020, the contents of each of which are incorporated herein by reference for all purposes.

FIELD OF THE DISCLOSURE The present disclosure relates generally to the field of filters, and in particular to antiviral filtration elements, filtration devices including such elements, and processes for manufacturing and methods of operating such elements. The present disclosure relates to filtration devices capable of filtering bacteria, viruses, other airborne particles or contaminants in liquids. The device is an oral and/or nasal air filter capable of removing and neutralizing harmful viruses from inhaled air contaminated with harmful viruses and from contaminated air exhaled from patients infected with harmful viruses. may be In particular, the present disclosure relates to such devices in the form of face masks. The present disclosure also relates to filter materials or members suitable for use in such face masks and other filtering devices.

Inhalation of air contaminated with harmful viruses and/or other microorganisms is a common route of infection for humans, especially health care workers and others who work with infected humans or animals. The air exhaled by infected persons is also known to be a source of contamination. Currently, the risk of infection from the so-called "COVID-19" novel coronavirus is of particular concern. A mask incorporating appropriate filter material is ideal for use as a barrier to prevent infection by this virus.

Air filters believed to be capable of removing such viruses and/or other microorganisms are known in the art. One type of such filter is a fibrous or particulate substrate or layer with an antiviral compound or and an antimicrobial compound. This compound captures and/or neutralizes viruses and/or other microorganisms of concern. Examples of such filter disclosures are summarized below.

For example, US Pat. No. 4,856,509 provides a face mask in which select portions of the mask contain a virus-disrupting agent such as citric acid. US Pat. No. 5,767,167 discloses airgel foams suitable for filtration media for trapping microorganisms such as viruses. US Pat. No. 5,783,502 provides a fabric substrate having cationic groups, such as quaternary ammonium cationic hydrocarbon groups, attached to antiviral molecules, particularly fabrics. U.S. Pat. No. 5,851,395 is directed to a virus filter comprising a filter material having deposited thereon a virus-capturing material based on sialic acid (a nine-carbon monosaccharide with carboxylic acid substituents on the ring) . US Pat. No. 6,182,659 discloses a virus removal filter based on a Group B Streptococcus culture. US Pat. No. 6,190,437 discloses an air filter for removing viruses from air comprising a carrier substrate impregnated with iodine resin. US Pat. No. 6,379,794 discloses filters based on glass and other elastic fibers impregnated with acrylic latex materials. U.S. Pat. No. 6,551,608 discloses a porous thermoplastic material substrate and an antiviral substance formed by sintering at least one antiviral agent with the thermoplastic. . US Pat. No. 7,029,516 discloses a filter system for removing particles from fluids comprising a non-woven polypropylene base deposited with an acidic polymer such as polyacrylic acid.

There is a continuing and very urgent need to improve such filters, especially in view of concerns about risks from "bird flu" and coronaviruses. The inventors have identified filter materials or members that can increase the level of removal of harmful viruses and/or other microorganisms from inhaled air and the level of neutralization of these species, resulting in improved nasal passages and /or enabled the use of such materials in oral filters. The same filter material can be used as a filtration member in other filter devices such as water and air purification, selected solvent separation and spilled oil recovery.

The present disclosure includes (a) a mask body configured to cover at least the mouth and nose of the wearer, and (b) fasteners (e.g., the mask body) for holding the mask in place on the wearer's face. and a pair of ear straps extending from opposite sides of the head of the wearer and configured to hook around the ears of the wearer, or elastic straps that hook around the head of the wearer. the mask body comprises (i) an air permeable outer layer (e.g. a fibrous sheet or piece of fabric, or a porous polymer membrane) preferably comprising a hydrophobic material (e.g. water-repellent fibers) and (ii) when the mask is worn (iii) a graphene or graphene foam layer disposed on the mask body; In one embodiment, the graphene or graphene foam layer is positioned between the outer layer and the inner layer. In another embodiment, the graphene or graphene foam layer is embedded in the outer layer. In another embodiment, the graphene or graphene foam layer is embedded in the inner layer. The graphene or graphene foam layer may be wholly or partially embedded in the outer layer or the inner layer. The graphene layer may comprise a plurality of separate monolayers or several layers of graphene sheets, and the graphene foam layer may comprise a graphene material, the graphene sheets and graphene material comprising pristine graphene, selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitrogen, doped graphene, chemically functionalized graphene, or combinations thereof.

In certain embodiments, the graphene sheet or foam layer is chemically attached to the surface of the outer layer (e.g., the inner surface) or the surface of the inner layer (surface facing the outer layer) with or without the use of adhesives or binders. are connected systematically.

In the disclosed face mask, the graphene layer preferably has a density of 0.005-1.7 g/cm ³ , a specific surface area of 10-3200 m ² /g, but a specific surface area of 50-3000 m ² /g or More preferably, it has a density of 0.1-1.2 g/cm ³ and the graphene foam layer has a density of 0.005-1.0 g/cm ³ or a specific surface area of 40-2600 m ² /g. More preferably, it has a specific surface area of 200-2000 m ² /g or a density of 0.01-0.5 g/cm ³ .

The weight ratio of the graphene or graphene foam layer to the outer layer or the weight ratio of the graphene or graphene foam layer to the inner layer is preferably 1/1000 to 1/0.1, preferably 1/100 to 1/ 1 is more preferred, and 5/100 to 25/100 is most preferred.

In some embodiments, the graphene or graphene foam layer is a separate layer embedded in at least one of the outer layer or the inner layer.

In the disclosed face mask, the outer layer or inner layer of the mask body may comprise a woven or non-woven construction of polymer or fiberglass. The outer or inner layer is preferably cotton, cellulose, wool, polyolefins (e.g. polyethylene and polypropylene), polyesters (e.g. PET), polyamides (e.g. nylon), rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, polyvinyl (carboxylic acid), biodegradable polymers, water-soluble polymers, copolymers thereof and combinations thereof.

The fasteners may comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around the ears of the wearer, or elastic straps that hook around the head of the wearer. good.

Preferably, the graphene sheets in the graphene layer or foam layer have an oxygen content of 5-50% by weight based on the total weight of the graphene sheets. Oxygen-containing functional groups on the surface of graphene are believed to be able to kill or deactivate specific microbial agents.

In the disclosed facemask, the mask body may further comprise an antimicrobial compound. Preferably, the mask body further comprises an antimicrobial compound distributed on the surface of the graphene sheet, and the graphene sheet has a specific surface area of 50-2630 m ² /g or is on the pore walls of the graphene foam. Such a high specific surface area allows the mask body to dramatically increase the surface area of antimicrobial compounds that can directly attack microbial pathogens (bacteria, viruses, etc.).

Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to the fabric or graphene sheet), sulfonamides, fluoroquinolones or combinations thereof.

The present disclosure also provides filtering materials (or members) for use in the aforementioned face masks or other types of filtering devices. In certain embodiments, the filtration material comprises a woven or nonwoven layer having two major surfaces and graphene or and a graphene foam layer.

In the filtration material, the graphene or graphene foam layer is preferably pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride. , doped graphene, chemically functionalized graphene, or a combination thereof. In some embodiments, the graphene sheets are chemically bonded to at least one of the major surfaces with or without the use of adhesives or bonding agents. In the filtration material, the graphene layer preferably has a density of 0.005-1.7 g/cm ² , a specific surface area of 10-3200 m 2 /g, a specific surface area of 50-3000 m ² /g or a specific surface area of 0.1-3000 m ² /g. It is more preferable to have a density of 1.2 g/cm ³ , a density of 0.005 to 1.0 g/cm ³ or a specific surface area of 10 to 2600 m ² /g, and a specific surface area of 200 to 2000 m ² /g or More preferably, it has a density of 0.1-1.2 g/cm ³ . The specific surface area is most preferably greater than 200 and the specific surface area density of the foam most preferably greater than 300 m ² /g.

In the filtration material, the graphene or graphene foam layer is preferably a separate layer partially or wholly embedded in the woven or non-woven fabric layer or at least partially embedded in its major surface. .

The present disclosure further provides a filtering device comprising the disclosed filtering material as a filtering member. The filtration device may be a water purification device, an air purification device, an oil recovery device or a solvent removal device.

Further provided in the present disclosure is a process for manufacturing the filtration material disclosed herein comprising the steps of (a) providing a layer of woven or non-woven fabric having two major surfaces; (b) depositing a graphene layer on at least one of the two major surfaces.

In certain embodiments, (b) comprises dispersing discrete graphene sheets in a gaseous medium to form a flowing fluid, with or without an adhesive; and C. impinging a flowing fluid on one side to allow said graphene sheets to adhere to said at least one major surface.

In certain preferred embodiments, (b) comprises dispersing discrete graphene sheets in a liquid medium with or without an adhesive to form a slurry; depositing the slurry on one side to form a wet graphene layer; and removing or drying the liquid medium from the wet graphene layer to form a graphene layer. Thermal or UV curable adhesives are more desirable.

Deposition procedures are preferably casting, coating (e.g., slot die coating, comma coating, reverse roll coating, etc.), spraying (e.g., air-assisted spraying, electrostatic charge-assisted spraying, ultrasonic spraying, etc.), printing (e.g., inkjet printing, screen printing, etc.), brushing, painting or a combination thereof.

The process is preferably a roll-to-roll or reel-to-reel process, comprising (a) (i) providing a roll of woven or nonwoven fabric; (iii) depositing a graphene layer on at least one of the two major surfaces of the fabric coated with the graphene layer; and (iv) collecting the fabric coated with the graphene layer onto a take-up roller.

The process may further include incorporating the filtering material into a mask body with attached fasteners to form a face mask.

The present disclosure provides a filtration member for use in a filtration device, the filtration member comprising a layer of air permeable membrane (e.g., woven or nonwoven sheet, porous polymer membrane, open cell membrane) having two major surfaces. foam strips, sheets of air-breathable paper, etc.) and a layer of chemically functionalized graphite flakes deposited on at least one of the two major surfaces or embedded in a layer of air-permeable membrane. and wherein the graphite flakes contain 1 wt% to 50 wt% (preferably 5 wt% to 35 wt%) of non-carbon elements selected from O, N, H, F, Cl, Br, I or combinations thereof. %) containing chemical functional groups.

In some embodiments, the layer of graphite flakes is chemically bonded to at least one of the major surfaces using an adhesive or bonding agent.

Preferably, the layer of graphite flakes has a specific surface area of 10-500 m ² /g.

In the filter member, the non-woven fabric is preferably cotton, cellulose, wool, polyolefin, polyester, polyamide, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymer, water-soluble polymer, and combinations thereof.

In certain embodiments, the disclosed filtration member further comprises an antimicrobial compound distributed on the surface of the graphite flakes. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

In some embodiments, the nonwoven of the filtration member comprises polymeric fibers and the antimicrobial compound is distributed on the surface of the polymeric fibers. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may contain an anti-bacterial compound.

The present disclosure also provides a filtering device comprising the filtering member described above as a functional component. The filtration device may be a water purification device, an air cleaning device, a solvent removal device, an oil recovery device or a face mask, especially a medical face mask or respirator.

In certain embodiments, the disclosed face mask comprises (a) a mask body configured to cover at least the mouth and nose of the wearer, and (b) holding the mask in place on the wearer's face. the mask body comprising: (i) an air permeable outer layer; (ii) an inner layer positioned toward the wearer when the mask is worn; and (iii) positioned between the outer and inner layers. or a filtration member as described above embedded in the outer layer or the inner layer.

Note that the layer of woven or non-woven fabric that supports the layer of graphite flakes may be the outer layer or the inner layer. In other words, a layer of chemically functionalized graphite flakes may be deposited on the inner surface of the outer layer or on the outer surface of the inner layer (opposite the wearer's face).

Accordingly, the present disclosure provides (a) a mask body configured to cover at least the mouth and nose of the wearer, and (b) a fastening system (e.g., , a pair of ear straps extending from opposite sides of the mask body and configured to hook around the ears of the wearer, or elastic straps that hook around the head of the wearer. wherein the mask body comprises (i) an air-permeable outer layer (e.g., a fibrous sheet or piece of fabric, or a porous polymer membrane), preferably comprising a hydrophobic material (e.g., water-repellent fibers); (iii) a chemically functionalized inner layer positioned between the outer and inner layers or embedded wholly or partially in the outer or inner layer; and a layer of expanded graphite flakes. Graphite flakes contain a chemical composition containing 1 wt% to 50 wt% (preferably 5 wt% to 35 wt%) of non-carbon elements selected from O, N, H, F, Cl, Br, I, or combinations thereof. Contains functional groups.

In general, the present disclosure also provides a face mask comprising chemically functionalized graphite flakes as an antiviral agent, wherein the graphite flakes are selected from O, N, H, F, Cl, Br, I, or combinations thereof chemical functional groups containing 1% to 50% by weight of non-carbon elements. Particularly useful are graphite flakes bearing chemical functional groups such as -COOH, -OH, >O, -F, -Cl, -Br, -I and/or _-NH2 .

In certain embodiments, the graphite flake layer is chemically bonded to the surface of the outer layer (eg, the inner surface) or the surface of the inner layer (the surface facing the outer layer) using an adhesive or bonding agent.

In the disclosed face mask the graphite flakes preferably have a specific surface area of 10-500 m ² /g.

The weight ratio of the graphite flake layer to the outer layer or the weight ratio of the graphite flake layer to the inner layer is preferably 1/1000 to 1/0.1, more preferably 1/100 to 1/1, and Most preferably 5/100 to 25/100.

In some embodiments, the graphite flake layer is a separate layer embedded in at least one of the outer layer or the inner layer.

In the disclosed facemask, the outer or inner layer of the mask body is composed of a woven or non-woven fabric structure of polymer or fiberglass, a porous polymer membrane (e.g., a porous PE-PP copolymer membrane, polytetrafluoroethylene or Teflon membrane), It may also include air permeable sheets of paper or combinations thereof. The outer or inner layer is preferably cotton, cellulose, wool, polyolefins (e.g. polyethylene and polypropylene), polyesters (e.g. PET), polyamides (e.g. nylon), rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, polyvinyl (carboxylic acid), biodegradable polymers, water-soluble polymers, copolymers thereof and combinations thereof.

The fasteners may comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around the ears of the wearer, or elastic straps that hook around the head of the wearer. good.

Preferably, the graphite flake layer has an oxygen or nitrogen content of 5 wt% to 50 wt%, or a halogen content of 5 wt% to 30 wt%, based on the total weight of the graphite flakes. Oxygen-, nitrogen-, or halogen-containing functional groups on graphite flake surfaces are believed to be capable of killing or deactivating specific microbial agents.

In the disclosed facemask, the mask body may further comprise an antimicrobial compound. Preferably, the mask body further comprises an antimicrobial compound distributed on the surface of the graphite flakes. Such a high specific surface area allows the mask body to dramatically increase the effective amount of antimicrobial compounds that can directly attack microbial pathogens (bacteria, viruses, etc.). Virtually all antimicrobial compounds are available.

Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to textiles or graphite flakes), sulfonamides, fluoroquinolones, hypericin, curcumin (including polymeric curcumin), or combinations thereof. good too.

FIG. 1 is a flow chart showing the most commonly used prior art process for producing graphene sheets. 2 is a schematic illustration of a face mask according to one embodiment of the present disclosure; FIG. FIG. 3A is a schematic diagram showing a process for producing intercalated and/or graphite oxide followed by exfoliated graphite worms and expanded graphite flakes. Figure 3B is an SEM image of exfoliated carbon containing interconnected graphite flakes (exfoliated carbon worms); become. FIG. 3C is another SEM image of graphite worms containing interconnected graphite flakes; when exposed to low intensity air jet milling, these worms become isolated expanded graphite flakes. FIG. 3D is a schematic diagram showing an approach to produce thermally expanded/exfoliated graphite structures containing interconnected graphite flakes; It becomes expanded graphite flakes. FIG. 4A is a schematic illustration of a face mask structure according to one embodiment, wherein the graphene, graphene foam or graphite flakes layer is a separate layer embedded in the outer layer. FIG. 4B is a schematic diagram of a face mask structure according to one embodiment, wherein the graphene, graphene foam or graphite flakes layer is a separate layer embedded in the inner layer.

The present disclosure provides filtration elements (members) and filtration devices including such members. Filtration devices may be selected from water filter devices, air filter devices, solvent purifiers, oil recovery devices or face masks (eg, surgical face masks such as N95 face masks, respirators).

The filtering member preferably comprises a layer of air-permeable membrane (e.g., woven or non-woven sheet, porous polymer membrane, open-cell foam strip, breathable paper sheet, etc.) having two major surfaces; a layer of chemically functionalized graphite flakes deposited on at least one of the two major surfaces or embedded in the layer of breathable membrane, the graphite flakes comprising O, N, H, F, It comprises chemical functional groups containing 1 wt% to 50 wt% (preferably 5 wt% to 35 wt%) of non-carbon elements selected from Cl, Br, I or combinations thereof.

In some embodiments, the layer of graphite flakes is chemically bonded to at least one of the major surfaces using an adhesive or bonding agent. Preferably, the layer of graphite flakes has a specific surface area of 10-500 m ² /g.

In the filter member, the non-woven fabric is preferably cotton, cellulose, wool, polyolefin, polyester, polyamide, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymer, water-soluble polymer, and combinations thereof.

In certain embodiments, the disclosed filtration member further comprises an antimicrobial compound distributed on the surface of the graphite flakes. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

In some embodiments, the nonwoven fabric of the filtration member comprises polymer fibers and the antimicrobial compound is distributed on the surface of the polymer fibers. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, organic silver idine antimicrobials, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

The present disclosure also provides a filtering device comprising the filtering member described above as a functional component. The filtration device may be a water purification device, an air cleaning device, a solvent removal device, an oil recovery device or a face mask, especially a medical face mask or respirator.

In certain embodiments, as shown schematically in FIG. 2, the disclosed mask includes: (a) a mask body configured to cover at least the wearer's mouth and nose; and (b) the wearer's face. fasteners (e.g., a pair of ear straps extending from opposite sides of the mask body and configured to hook around the wearer's ears, or the wearer's The mask body comprises (i) an air-permeable outer layer (e.g., a fiber sheet or piece of fabric) comprising a hydrophobic material (e.g., water-repellent fabric); ii) an inner layer positioned on the side of the wearer when the mask is worn; and (iii) a graphene material or foam or graphite positioned between the outer and inner layers or wholly or partially embedded in the outer or inner layer. and a layer of flakes.

The graphene or graphene foam layer preferably comprises pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, doped graphene, It comprises a plurality of discrete single or few layers of graphene sheets or graphene materials selected from chemically functionalized graphene or combinations thereof. Face masks include surgical masks, respirators and non-medical masks.

The graphite flakes contain 1 wt% to 50 wt% (preferably 5 wt% to 35 wt%) of non-carbon elements selected from O, N, H, F, Cl, Br, I or combinations thereof It has a chemical functional group. The fastener has one or more portions that engage the face mask body and one or more portions of the fastener that engage the wearer. In one embodiment, a portion of the elastic strap is sewn to the face mask body while another portion of the elastic strap wraps around the wearer's ears.

Each outer layer or inner layer may be a multi-layer or multi-layer structure. In some embodiments, the graphene, graphene foam or graphite flakes layer may be embedded as one of multiple layers in either the outer layer (FIG. 4(A)) or the inner layer (FIG. 4(B)). The air permeable structure may comprise an air permeable membrane such as a fibrous substrate or fabric, which may be either woven or non-woven. Examples of woven materials include cotton, cellulose, wool, polyolefins (e.g. PE and PP), polyesters (e.g. PET and PBT), polyamides (e.g. nylon), rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl and any other synthetic polymer that can be processed into fibers. Examples of nonwoven materials include polypropylene, polyethylene, polyester, nylon, PET and PLA. Nonwovens, which may be in the form of nonwoven sheets or pads, are preferred in the presently disclosed devices.

Nonwoven polyester is a preferred air permeable structure because some of the desired antiviral or antimicrobial compounds, such as acidic polymers, adhere better to the polyester material. Polypropylene nonwovens are also preferred. The graphene sheet or foam or graphite flake layers/structures studied here appear to be compatible with all polymer fiber-based fabric structures. The grade of fibrous substrate or fabric that can be used to support the graphene sheets or foam or graphite flakes may be practically determined to achieve adequate air flow through, the density may be known from face mask technology to provide a mask of

Non-woven polypropylene, of the type traditionally used for surgical masks and the like, is widely available in sheet form. Suitable grades of nonwoven polypropylene include well known grades commonly used in surgical face masks. Typical nonwoven polypropylene materials that have been found suitable for use in face masks or other filtration devices have area weights of 10-50 g/m ² (gsm). Other suitable material weights can be readily determined empirically. Typical nonwoven polyester suitable for use in filtration devices have areal weights of 10 to 300 g/m ² . For face mask applications, polyester materials with a weight between 20 and 100 g/m ² are preferred. Such materials are commercially available. Other suitable materials can be readily determined empirically.

Alternatively, the porous layer substrate other than nonwovens or wovens may be in other forms such as open cell foams, eg polyurethane foams which are also used in air filters. The graphene foam layers and polymer foam layers are then bonded or laminated together to form a structurally complete body. The graphite flake layer and polymer foam layer are then bonded or laminated to form a structurally complete body. Alternatively, the graphite flakes may be deposited onto the surface of the foam (or any other type of breathable membrane) using casting, coating, printing, spraying, painting, or the like.

Again, surgical masks and face masks, including respirators, are generally made of non-woven fabrics, which are superior in bacterial filtration and breathability, while maintaining less slippage than woven fabrics. do. The material most commonly used to form them is polypropylene, but they can also be formed from polystyrene, polycarbonate, polyethylene or polyester, and the like. A mask material of 20 g/m ² or gsm is typically formed in a spunbond process that involves extruding molten plastic from a mold onto a conveyor. The material is extruded into a web and the strands bond together as they cool. 25gsm fabrics are usually formed by a meltblowing process in which the plastic is extruded from a mold through a die with hundreds of small nozzles and blown by hot air into very fine fibers which are then cooled on a conveyor. Combined above. These fibers are typically less than 1 micron in diameter. The graphene foam layer may be combined with the plastic fabric during or after the fabric manufacturing procedure. The graphite flake layer may be combined with the polymer fabric during or after the fabric manufacturing procedure.

Surgical masks are generally constructed from a multi-layer construction, generally by covering a layer of fabric on both sides with a nonwoven bonded fabric. Nonwoven materials are less expensive to manufacture and cleaner because they are disposable. Structures incorporated as part of the mask body may be formed of three or four layers. These disposable masks are often made with two filter layers that are effective in filtering out particles such as bacteria larger than 1 micron. The filtration level of the mask varies depending on the fibers, manufacturing process, web construction and cross-sectional shape of the fibers. In the disclosed mask, the graphene or graphene foam or graphite flakes layer can be incorporated as one of multiple layers, but not directly exposed to the atmosphere (not the outermost layer) and directly with the wearer's face. It is preferred that they do not touch (not the innermost layer). The mask may be formed on a machine line that creates the nonwoven fabric from a bobbin, ultrasonically welds the layers together, and stamps nose strips, ear loops and other components onto the mask. These procedures are well known in the art.

Respirators also have multiple layers. The outer layers on both sides may be formed from a protective nonwoven with a density of 20-100 g/m ² to create a barrier to the external environment and, on the inside, to the wearer's own exhaled air. A pre-filtration layer follows which can be of density 250 g/m ² . It is typically a needled nonwoven fabric produced through a hot calendering process in which the plastic fibers are thermally bonded by passing the plastic fibers through high pressure heated rolls. A graphene or graphene foam or graphite flakes layer may be used to partially or wholly replace this layer. In the case of partial replacement, graphene foams or sheets or graphite flakes may be deposited or bonded onto the primary surface of this needled nonwoven layer. This makes the pre-filtration layer thicker and stiffer to form the desired shape when the mask is in use. The final layer may be a highly efficient meltblown electret nonwoven material that determines the filtration efficiency. This meltblown layer may be deposited or bonded with a graphene or graphene foam or graphite flakes layer instead of or in addition to the pre-filtration layer.

An antiviral or antimicrobial compound may be deposited on the graphene sheet surface or pore wall graphene surface of the graphene foam or graphite flakes. This deposition may occur before or after the graphene sheets or foams are formed into the graphene layer, or before or after the graphite flakes are formed into the layer. Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobials, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to fabric or graphene sheets), sulfonamides, fluoroquinolones, hypericin, curcumin (including polymeric curcumin), or combinations thereof. good.

Acidic polymers have been found to be effective in trapping and neutralizing viruses in air passing through such filtration members (substrates) featuring acidic polymers. Without wishing to be bound by any particular theory, upon contact with the surface of the substrate, the virus interacts with the polymer, is trapped, and is exposed to the local low pH environment of the acidic polymer (eg, pH value 2.00). 8-5) are thought to inactivate the virus. The filter members and filtration devices comprising such members disclosed herein are thus effective against viruses that cause colds, influenza, SARS, RSV, avian flu, coronaviruses, and mutated serotypes thereof. It is thought that it can be effective for

Poly-(carboxylic acid) polymers, as examples of acidic polymers, typically have --COOH groups in their structure, or readily cleavable acid anhydride groups, which readily cleave to produce --COOH groups. are polymers containing derivative groups such as carboxylic acid ester groups. A poly-(carboxylic acid) polymer may have —COOH groups (or derivative groups) directly linked to its backbone, or the polymer may have —COOH (or derivative) groups branched from the backbone. It may also be a so-called graft polymer or dendritic polymer, which is attached to side chains attached to the polymer.

The functionalized expanded graphite flakes disclosed herein can be readily formed to contain --COOH groups on their surfaces or edges. These functional groups carried on graphite flakes are also expected to have antiviral properties.

Generally speaking, the present disclosure also provides a face mask comprising chemically functionalized graphite flakes as an antiviral agent, wherein the graphite flakes are O, N, H, F, Cl, Br, I or and chemical functional groups containing 1% to 50% by weight of non-carbon elements selected from combinations of Particularly useful are graphite flakes bearing chemical functional groups such as -COOH, -OH, >O, -F, -Cl, -Br, -I and/or _NH2 .

It is imperative that manufactured face masks and respirators are sterilized before leaving the factory.

The manufacture of graphene and graphene foams is well known in the art and may be further described below for the convenience of the reader.

Carbon materials may have an essentially amorphous structure (glassy carbon), highly organized crystallites (graphite), or graphite crystallites and defects of varying proportions and sizes dispersed in an amorphous matrix. A full range of intermediate structures characterized by Graphite crystallites are usually composed of a large number of graphene sheets or basal planes held together by van der Waals forces along the c-axis, which is oriented perpendicular to the basal planes. These graphite crystallites are typically micron or nanometer sized. Graphite crystallites are dispersed or connected in crystal defects or amorphous phases in graphite particles, which may be graphite flakes, carbon/graphite fiber segments, carbon/graphite whiskers, or carbon/graphite nanofibers. In other words, the graphene planes (the hexagonal lattice structure of carbon atoms) make up a significant portion of the graphite particles.

A single-layer graphene sheet is composed of carbon atoms occupying a two-dimensional hexagonal lattice. Multilayer graphene is a platelet composed of multiple graphene planes. Individual single-layer graphene sheets and multi-layer graphene platelets are collectively referred to herein as nano-graphene platelets (NGPs) or graphene materials. NGP includes pristine graphene (essentially 99% of carbon atoms), slightly oxidized graphene (less than 5 wt% oxygen), graphene oxide (>5 wt% oxygen), slightly fluorinated modified graphene (less than 5 wt% fluorine), fluorinated graphene ((5 wt% or more fluorine), other halogenated graphenes and chemically functionalized graphene.

Our research group was the first to discover graphene [B. Z. Jang and W.J. C. Huang, "Nano-scaled Graphene Plates", US patent application Ser. No. 10/274,473 filed Oct. 21, 2002, now US Pat. ]. The fabrication process of NGP and NGP nanocomposites was recently reviewed by us [Bor Z. Jang and A Zhamu, "Processing of Nano Graphene Platelets (NGPs) and NGP Nanocomposites: A Review," J. Am. Materials Sci. 43 (2008) 5092-5101]. The manufacture of various types of graphene sheets is well known in the art.

For example, chemical processes for producing graphene sheets or platelets typically combine a powder of graphite or other graphite material with a mixture of concentrated sulfuric acid, nitric acid, and an oxidizing agent such as potassium permanganate or sodium perchlorate. to form a reaction mass that typically requires 5-120 hours to complete the chemical intercalation/oxidation reaction. When the reaction is complete, the slurry is subjected to repeated steps of rinsing and washing with water. The purified product is commonly referred to as graphite intercalation compound (GIC) or graphite oxide (GO). A suspension containing GIC or GO in water may be sonicated to produce isolated/separated graphene oxide sheets dispersed in water. The resulting product is usually highly oxidized graphene (i.e., graphene oxide with high oxygen content), and to obtain reduced graphene oxide (RGO), highly oxidized graphene is chemically or It must be thermally reduced.

Alternatively, the GIC suspension may be dried to remove water. The dry powder is then subjected to thermal shock treatment. This involves placing the GIC in a furnace preset at a temperature of typically 800-1100° C. (more typically 950-1050° C.) and subjecting it to high shear or sonication to produce separated graphene sheets. This can be achieved by producing exfoliated graphite (or graphite worms) that can be obtained.

Alternatively, the graphite worms may be recompressed into a thin film form to obtain a flexible graphite sheet. Flexible graphite sheets are commercially available from many sources around the world.

The starting graphite material may be selected from natural graphite, synthetic graphite, highly oriented pyrolytic graphite, graphite fibers, graphite nanofibers, graphite fluoride, chemically modified graphite, mesocarbon microbeads, partially crystalline graphite or combinations thereof. .

The pristine graphene sheets may be produced by well-known liquid phase exfoliation or metal-catalyzed chemical vapor deposition (CVD).

Graphene thin films, flexible graphite sheets and synthetic graphite thin films are generally regarded as three radically different and distinct classes of materials.

As shown schematically at the top of FIG. 1, bulk natural graphite consists of multiple grains (graphite single crystals or crystallites) with grain boundaries (amorphous or defect zones) demarcating adjacent graphite single crystals. 3D graphite material with each graphite grain composed of grains). Each grain is composed of multiple graphene planes oriented parallel to each other. Graphene planes or hexagonal carbon atom planes in graphite crystallites are composed of carbon atoms occupying a two-dimensional hexagonal lattice. In a given grain or single crystal, the graphene planes are stacked and bonded in the crystallographic c-direction (perpendicular to the graphene planes or basal planes) via van der Waals forces. The graphene interplanar spacing of natural graphite material is about 0.3354 nm.

Artificial graphite materials contain component graphene planes, but typically have graphene plane spacings d ₀₀₂ of 0.32 nm to 0.36 nm (more commonly 0.3339 to 0.3465 nm) as measured by X-ray diffraction. have. Many carbon or quasi-graphitic materials also contain graphite crystallites (also called graphite crystallites, domains or grains) each composed of stacked graphene planes. These include mesocarbon microbeads (MCMB), mesophase carbon, soft carbon, hard carbon, coke (e.g. needle coke), carbon or graphite fibers (including vapor grown carbon nanofibers or graphite nanofibers) and multi-layered carbon. Nanotubes (MW-CNT) are included. The spacing between two graphene rings or walls of MW-CNTs is about 0.27-0.42 nm. The most common spacing values for MW-CNTs are in the range of 0.32-0.35 nm and are largely independent of the synthesis method.

"Soft carbon" means that the orientation of the hexagonal carbon planes (or graphene planes) within one domain and the orientation within adjacent graphite domains are such that these domains exceed 2000°C (more commonly 2500°C). Note that reference is made to carbon materials containing graphite domains that are not too mismatched with each other so that they can be easily fused when heated to temperatures above °C. Such heat treatment is commonly referred to as graphitization. Soft carbon can thus be defined as a graphitizable carbonaceous material. In contrast, “hard carbon” can be defined as a carbonaceous material comprising highly misoriented graphite domains that cannot be thermally fused together to obtain larger domains, i.e., hard Carbon cannot be graphitized.

The spacing between the constituent graphene planes of the graphite crystallites of natural graphite, synthetic graphite and other graphitic carbon materials listed above can be expanded by using several expansion treatment approaches (i.e., d ₀₀₂ The spacing increases from 0.27-0.42 nm in the original range to 0.42-2.0 nm), and the expansion treatment approaches include oxidation, fluorination, chlorination, bromination, iodination, nitrogenation, inter Calation, combination of oxidative intercalation of graphite or carbon materials, combination of fluorination and intercalation, combination of chlorination and intercalation, combination of bromination and intercalation, combination of iodination and intercalation or a combination of nitration and intercalation.

More specifically, since the van der Waals forces that hold parallel graphene planes together are relatively weak, the natural graphite can be processed. This enlarges the spacing of the graphite material while substantially preserving the layered properties of the hexagonal carbon layers. The interplanar spacing of graphite crystallites (also called inter-graphene spacing) can be increased (enlarged) by several approaches including oxidation, fluorination and/or intercalation of graphite. This is shown schematically in FIG. 3(D). The presence of intercalants, oxygen-containing groups or fluorine-containing groups helps increase the spacing between two graphene planes in graphite crystallites.

A graphite/carbon material with an enlarged d-spacing is placed without restriction (i.e., allowed to increase in volume at will) (e.g., the carbon material in a furnace preset at a temperature typically between 800 and 2500° C.). When exposed to thermal shock, the interplanar spacing between specific graphene planes can be greatly increased (actually exfoliated). Under these conditions, the thermally exfoliated graphite/carbon material appears worm-like, with each graphite worm composed of many graphite flakes that remain interconnected (see Fig. 3(C)). ). However, these graphite flakes typically have interflake pores in the pore size range of 20 nm to 10 μm. These worms may be disintegrated (eg, using an air jet mill) to produce separated expanded graphite flakes.

Alternatively, intercalated, oxidized or fluorinated graphite/carbon materials with increased d-spacings are exposed to moderate temperatures (100-800° C.) under constant volume conditions for sufficient time. may Conditions may be adjusted to obtain a limited exfoliation product with interflake pores with an average size of 2-20 nm. This is referred to herein as a constrained expansion/exfoliation process. We have surprisingly observed that Al cells with graphite/carbon cathodes with an interplanar spacing of 2-20 nm can achieve high energy density, high power density and long cycle life.

In one process, by intercalating natural graphite particles with strong acids and/or oxidizing agents to obtain graphite intercalation compounds (GIC) or graphite oxides (GO), as shown in FIG. , a graphite material having an enlarged interplanar spacing is obtained. The presence of chemical species or functional groups in the interstitial spaces between graphene planes increases the inter-graphene spacing _d002 as determined by X-ray diffraction, thereby holding the graphene planes together along the c-axis direction. greatly reduce power. GIC or GO is prepared by soaking natural graphite powder (100 in FIG. 3(A)) in a mixture of sulfuric acid, nitric acid (an oxidizing agent) and another oxidizing agent (e.g. potassium permanganate or sodium perchlorate). Most often generated. The resulting GIC (102) is actually a type of graphite oxide (GO) particles when an oxidizing agent is present during the intercalation procedure. The GIC or GO is then repeatedly washed and rinsed in water to remove excess acid, and a graphite oxide suspension or dispersion comprising discrete, visually identifiable graphite oxide particles dispersed in water. produce liquid.

Water may be removed from the suspension to obtain "expandable graphite", which is essentially a mass of dry GIC or dry graphite oxide particles. The inter-graphene spacing d ₀₀₂ in dry GIC or graphite oxide particles is typically in the range 0.42-2.0 nm, more typically in the range 0.5-1.2 nm. Note that "expandable graphite" is not "expanded graphite" (further described below).

When expandable graphite is exposed to temperatures typically in the range of 800-2500° C. (more commonly 900-1050° C.) for about 30 seconds to 2 minutes, the GIC undergoes a rapid volume expansion of 30-300 times, exfoliated graphite” or “graphite worms” (104). Each graphite worm is a collection of exfoliated but largely unseparated graphite flakes that remain interconnected (FIGS. 3B and 3C). In exfoliated graphite, individual graphite flakes (each with one to several hundred graphene planes stacked together) are widely spaced from each other, typically with spacings of 2.0 nm to 10 μm. However, they remain physically interconnected, forming an accordion or worm-like structure.

In the graphite industry, graphite worms can be recompressed to obtain flexible graphite sheets or foils (106), typically having a thickness in the range of 0.1 mm (100 μm) to 0.5 mm (500 μm). can. Such flexible graphite sheets may be used as a type of graphite heat spreader element.

Alternatively, in the graphite industry, for the purpose of producing mostly graphite flakes or so-called "expanded graphite" flakes (108) containing platelets with a thickness greater than 100 nm (thus, by definition, not nanomaterials), One may choose to simply break up the graphite worms using a low intensity air mill or shearing machine. "Expanded graphite" is clearly neither "expanded graphite" nor "exfoliated graphite worms." Rather, "expandable graphite" can be thermally exfoliated to obtain "graphite worms", which in turn undergo mechanical shearing to form interconnected graphite flakes in other ways. to obtain "expanded graphite" flakes. Expanded graphite flakes typically have the same or similar interplanar spacing (typically 0.335-0.36 nm) as their original graphite. A plurality of expanded graphite flakes may be roll-pressed together to form a graphite-like film, which is one variation of a flexible graphite sheet. Alternatively, preferably after chemical functionalization, a plurality of expanded graphite flakes may be sprayed or coated onto the surface of the nonwoven layer to produce the filtration member.

Alternatively, exfoliated graphite or graphite worms may be prepared as disclosed in our US patent application Ser. To separate monolayer and multilayer graphite sheets (collectively NGP, 112) may be formed. Single-layer graphene can be as thin as 0.34 nm, while multilayer graphene can have a thickness of up to 100 nm, but is more commonly less than 3 nm (commonly referred to as few-layer graphene). A plurality of graphene sheets or platelets may be formed into a sheet of NGP paper (114) using a papermaking process.

In GIC or graphite oxide, the separation between graphene planes increases from 0.3354 nm in natural graphite to 0.5-1.2 nm in highly oxidized graphite oxide, with van der Waals holding adjacent planes together. greatly weakened. Graphite oxide may have an oxygen content of 2% to 50% by weight, more typically 20% to 40% by weight. GIC or graphite oxide may undergo a special treatment referred to herein as "constrained thermal expansion". When the GIC or graphite oxide is subjected to thermal shock (eg, 800-1050° C.) in a furnace and allowed to expand freely, the final product is exfoliated graphite worms. However, if the GIC or graphite oxide mass is subjected to constraining conditions (e.g., under constant volume conditions or confined in an autoclave under uniaxial compression in a mold), then 150°C to 800°C (more While heated slowly (typically up to 600° C.) for a sufficient period of time (typically 2 minutes to 15 minutes), the degree of expansion can be suppressed and controlled and the product is: 2. It can have an interflake spacing of 0 nm to 20 nm, or more desirably 2 nm to 10 nm.

Note that by forming graphite fluoride (GF) instead of GO, "expandable graphite" or graphite with extended interplanar spacing can be obtained. The interaction of _F2 with graphite in fluorine gas at high temperatures produces (CF) _n to ( _C2F ) _n covalently bonded graphite fluoride, whereas at low temperatures, the graphite intercalation compound (GIC ) C _x F (2≤x≤24) are formed. In (CF) _n , the carbon atoms are sp3 hybridized and thus the fluorocarbon layer is corrugated consisting of trans-coupled cyclohexane chair. In (C ₂ F) _n only half of the C atoms are fluorinated and all pairs of adjacent carbon sheets are linked together by covalent C—C bonds. Systematic studies on fluorination reactions have shown that the resulting F/C ratio is dependent on the fluorination temperature, the partial pressure of fluorine in the fluorination gas, and the degree of graphitization, particle size and specific surface area of the graphite precursor. It has been shown to depend largely on physical properties. In addition to fluorine ( _F2 ), other fluorinating agents (e.g. mixtures of _F2 with _Br2 , _Cl2 or _I2 ) may be used, but most of the available literature fluorination with _F2 gas in the presence of oxides.

Expanded graphite flakes (with or without oxygen-containing species bound thereto) are exposed to gas molecules of F ₂ , Br ₂ , Cl ₂ or I ₂ to form F-, Br-, Cl- or I Expanded graphite flakes with contained functional groups are produced.

We find that low-fluorinated graphite, _CxF (2≤x≤24), obtained from electrolytic fluorination typically has inter-graphene spacings ( _d002 ). d ₀₀₂ spacing greater than 0.5 nm only when x in C _x F is less than 2 (i.e. 0.5≦x≦2) (in fluorinated graphite produced by gas phase fluorination or chemical fluorination procedures) can be observed. When x of _CxF is less than 1.33 (ie, 0.5≤x≤1.33), d ₀₀₂ spacing greater than 0.6 nm can be observed. This highly fluorinated graphite is obtained by fluorination at high temperatures (>>200° C.) for a sufficiently long time, preferably under pressures above 1 atmosphere, more preferably above 3 atmospheres. For reasons that remain unclear, the electrofluorination of graphite gives products with d-spacings of less than 0.4 nm, despite x values of 1-2 for the products C _x F. F atoms electrochemically introduced into graphite tend to reside at defects such as grain boundaries rather than between graphene planes, and as a result may not act to expand the interplanar spacing between graphenes. .

Nitrification of graphite can be carried out by exposing graphite oxide material or expanded graphite flakes to ammonia at elevated temperatures (200-400° C.). Nitrification can be carried out by the hydrothermal method at low temperatures, eg by sealing the GO and ammonia in an autoclave and then increasing the temperature to 150-250°C.

In addition to N, O, F, Br, Cl or H, the presence of other chemical species between graphene planes (e.g. Na, Li, K, Ce, Ca, Fe, _NH4 , etc.) can increase the inter-plane spacing. It can act to expand and create room for the electrochemically active material to be accommodated therein. In this work, we found that the enlarged interstitial space between graphene planes (hexagonal carbon planes or basal planes), especially when the space is between 2.0 nm and 20 nm, contains Al + ³ ions and other anions (electrolyte component ) have been found to be surprisingly accommodating as well. Graphite can be ion-exchanged subsequently chemically or electrochemically with metal elements (Bi, Fe, Co, Mn, Ni, Cu, etc.) Na, Li, K, Ce, Ca, _NH4 or their It can be electrochemically intercalated with such chemical species as combinations. All of these chemical species can function to increase the interplanar spacing. The spacing is dramatically enlarged (exfoliated) to create interflake pores 20 nm to 10 μm in size (e.g., by exposing Na or Li intercalated graphite to water or a mixture of water and alcohol). can have

Once the graphene sheets are produced, the graphene sheets can be formed into a mask body according to some embodiments of the present disclosure. One process for making a filtration material or member disclosed herein includes the steps of (a) providing a layer of woven or nonwoven fabric having two major surfaces; depositing a graphene layer on at least one of them.

Sub-process (b) disperses discrete graphene sheets in a gaseous medium to form a flowing fluid, with or without an adhesive, and dispersing the flowing fluid on at least one of the two major surfaces. and allowing the graphene sheets to adhere to the at least one major surface.

Alternatively, sub-process (b) comprises dispersing discrete graphene sheets in a liquid medium with or without an adhesive to form a slurry, and applying the slurry to at least one of the two major surfaces. Depositing on one side to form a wet graphene layer, and removing or drying the liquid medium from the wet graphene layer to form the graphene layer. Thermal or UV curable adhesives are more desirable.

Deposition procedures are preferably casting, coating (e.g., slot die coating, comma coating, reverse roll coating, etc.), spraying (e.g., air-assisted spraying, electrostatic charge-assisted spraying, ultrasonic spraying, etc.), printing (e.g., inkjet printing, screen printing, etc.), brushing, painting or a combination thereof.

The process is preferably a roll-to-roll or reel-to-reel process, sub-process (a) comprising the steps of (i) providing a roll of woven or non-woven fabric; , continuously feeding from a roll (mounted on rollers or reels) to a deposition zone; and (iii) depositing a graphene layer on at least one of the two major surfaces to form a graphene layer coated fabric. and (iv) collecting the fabric coated with the graphene layer onto a take-up roller.

Generally speaking, foams or foamed materials are composed of pores (or cells) and pore walls (solid material). The pores can be interconnected to form open-cell foams, which are preferred over closed-cell foams when practicing the present disclosure. Graphene foams are composed of pores and pore walls that contain graphene material. There are four main methods of manufacturing graphene foams.

The first method is the hydrothermal reduction of graphene oxide hydrogels, which typically involves sealing the graphene oxide (GO) aqueous suspension in a high-pressure autoclave and placing the GO suspension under high pressure (several tens of or several hundred atmospheres), usually in the range of 180 to 300° C. for a long time (usually 12 to 36 hours). A useful reference for this method is given here: Y. Xu et al., "Self-Assembled Graphene Hydrogel via a One-Step Hydrothermal Process," ACS Nano April 2010, 4324-4330.

A second method is based on a template-assisted catalytic CVD process, which involves CVD deposition of graphene onto a sacrificial template (eg, Ni foam). The graphene material conforms to the shape and dimensions of the Ni foam structure. The Ni foam is then etched using an etchant, leaving a monolith of graphene framework that is essentially an open cell foam. A useful reference for this method is given here: Zongping Chen et al., "Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapor deposition", Nature Materials, 10 (June 2011) 424-428.

A third method of fabricating graphene foams also utilizes sacrificial materials (eg, colloidal polystyrene particles, PS) coated with graphene oxide sheets using a self-assembly approach. For example, Choi et. and generation of 3D macropores by removal of PS beads. [B. G. Choi et al., "3D Macroporous Graphene Frameworks for Supercapacitors with High Energy and Power Densities," ACS Nano, 6 (2012) 4020-4028] Choi et al. and the positively charged PS suspension Filtration ordered self-supporting PS/CMG papers were produced starting from separate preparations. A mixture of CMG colloid and PS suspension was dispersed in solution under controlled pH (=2) and the two compounds had the same surface charge (zeta potential value was +13±2.0 for CMG). 4 mV, +68±5.6 mV for PS). When the pH was raised to 6, CMG (zeta potential = -29 ± 3.7 mV) and PS spheres (zeta potential = +51 ± 2.5 mV) assembled due to electrostatic interactions and hydrophobic properties between them. , which were then integrated into the PS/CMG composite paper through a filtration process.

A fourth method for fabricating solid graphene foams composed of multiple pores and pore walls was previously invented by us [Aruna Zhamu and Bor Z.; Jang, "Highly Conductive Graphene Foams and Process for Producing Same," U.S. Patent Application Serial No. 14/120,959 (July 17, 2014)]. The process:
(a) providing a graphene dispersion comprising a graphene material dispersed in a liquid medium, wherein the graphene material comprises pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, and bromide; selected from graphene, graphene iodide, graphene hydride, graphene nitride, graphene chemically functionalized, or combinations thereof, and the dispersion optionally comprises a blowing agent;
(b) dispersing and depositing the graphene dispersion on the surface of a supporting substrate (e.g., plastic film, rubber sheet, metal foil, glass sheet, paper sheet, etc.) to form a wet layer of graphene material; , the dispersing and depositing procedure comprises exposing the graphene dispersion to an orientation-induced stress;
(c) partial or complete removal of the liquid medium from the wet layer of the graphene material to remove non-carbon elements (e.g., O, H, N, B, F, Cl, Br, I) in amounts of 5% or more by weight; etc.);
(d) drying the dried layer of graphene material at a first heat treatment temperature of 100° C. to 3200° C. sufficient to induce volatile gas molecules from non-carbon elements, or 0.01 to 1.7 g/cm ^{3 ;} (more typically 0.1-1.5 g/cm ³ , still more typically 0.1-1.0 g/cm ³ , most typically 0.2-0.75 g/cm ³ ) or a specific surface area of 50-3000 m ² /g (more typically 200-2000 m ² /g, most typically 500-1500 m ² /g). heat treating at a desired heating rate sufficient to activate the blowing agent.

The graphene material contains non-carbon elements (e.g., O , H, N, B, F, Cl, Br, I, etc.), this optional blowing agent is not required. A subsequent high temperature treatment removes most of those non-carbon elements from the graphene material and helps to produce volatile gaseous species that create pores or cells in the solid graphene material structure. In other words, very surprisingly, these non-carbon elements act as blowing agents. Therefore, an externally added blowing agent is optional (not essential). However, the use of blowing agents can provide additional flexibility in adjusting or tailoring porosity levels and pore sizes for desired applications. Blowing agents are usually required when the content of non-carbon elements is less than 5%, such as in pristine graphene, which is essentially all carbon.

Graphene foams produced by the fourth method have the highest thermal conductivity of all graphene foam materials and highly reversible and durable elastic deformation in tension or compression. and allows good long-term contact between the fabric layers of the filtration member or filtration device.

The process and process of forming the face mask includes incorporating graphene or graphene foam or graphite flake reinforced filtration material (members) into a mask body to which fasteners (e.g., elastic straps) are attached to form the face mask. It's okay.

The fabric or foam coated with the graphene layer or the graphite flake layer has fine pores (<2 nm), mesoscale pores with pore sizes from 2 nm to 50 nm or larger pores (preferably from 50 nm to 1 μm). can be formed to include Based on well-controlled pore size alone, this graphene layer coated or foam or graphite flake layer supported by fabric can be an excellent filter material for air or water filtration.

Additionally, the chemistry of the graphene or graphene pore walls or graphite flake surfaces can be independently controlled to impart different amounts and/or types of functional groups to the graphene sheets or graphite flakes (e.g., or by the percentage of O, F, Cl, Br, I, N, H, etc. in the flakes). In other words, in the design and manufacture of graphene-coated or graphite-flake-coated fabrics, by simultaneously or independently controlling both the pore size and chemical functionality at different sites of the internal structure or porous graphite-flake layer. Unprecedented flexibility or degree of freedom is provided, which has many unexpected properties, synergistic effects and usually mutually exclusive exhibit a unique combination of properties that are considered to be (eg, part of the structure is hydrophobic and other parts are hydrophilic; or the filtering structure is hydrophobic and lipophilic). A surface or material is said to be hydrophobic if water is repelled from this material or surface, and a water droplet placed on a hydrophobic surface or material forms a large contact angle. A surface or material is said to be lipophilic if it has a strong affinity for oil rather than water. The method allows precise control of hydrophobicity, hydrophilicity and lipophilicity.

The present disclosure also provides an oil remover, oil separator or oil recovery device comprising the graphene or graphene foam layer coating or bonded fabric of the present invention as an oil absorbing or separating element. Also provided is a solvent eliminator or solvent separation device comprising a fabric coated or bonded with a graphene or graphene foam layer as a solvent absorbing element.

A major advantage of using the graphene-coated or graphene foam-bonded fabric or graphite flake-bonded fabric structure of the present invention as an oil absorbing element is its structural integrity. Because graphene sheets or foams or graphite flakes have a high degree of structural integrity, and because the foam structure can be chemically bonded to the fabric layer by adhesives, the resulting structure can be subjected to repeated oil absorption operations. It will not collapse even if you go.

Another major advantage of the technique of the present invention is its ability in designing and forming an oil absorbing element capable of absorbing large amounts of oil while still maintaining its structural shape (without significant expansion). Flexible. This amount depends on the specific pore volume of the filtration structure.

The present disclosure also provides methods for separating/recovering oil from oil-water mixtures (eg, oil spill water or wastewater from oil sands). The method comprises the steps of (a) providing an oil-absorbing element comprising a fabric coated or bonded with a graphene or graphene foam layer or a fabric bonded with a chemically functionalized graphite flake layer; and (b). (c) removing the oil-absorbing element from the mixture and extracting the oil from the element. Preferably, the method includes the step of (d) reusing the element.

Additionally, the present disclosure provides methods for separating organic solvents from solvent-water mixtures or from multi-solvent mixtures. The method comprises the steps of: (a) providing an organic solvent-absorbing element comprising a fabric structure coated or bonded with a full graphene or graphene foam layer or a fabric bonded with a graphite flake layer; and (b) an organic solvent-water mixture. or contacting the element with a multi-solvent mixture containing a first solvent and at least a second solvent; and (c) the element absorbs organic solvent from the mixture, or absorbs the first solvent from at least the second solvent and (d) removing the component from the mixture and extracting the organic solvent or first solvent from the component. Preferably, the method includes the step of (e) reusing the solvent absorbent element.

The following examples are used to illustrate certain details of the best mode of carrying out the disclosure, and should not be construed as limiting the scope of the disclosure.

Example 1: Preparation of monolayer graphene sheets and graphene layers from mesocarbon microbeads (MCMB) Mesocarbon microbeads (MCMB) were obtained from China Steel Chemical Co., Kaohsiung, Taiwan. supplied from. This material has a density of about 2.24 g/cm ³ and a median particle size of about 16 μm. MCMB (10 grams) was intercalated with an acidic solution (sulfuric acid, nitric acid and potassium permanganate in a ratio of 4:1:0.05) for 48-96 hours. After the reaction was completed, the mixture was poured into deionized water and filtered. The intercalated MCMB was washed repeatedly with a 5% solution of HCl to remove most of the sulfate ions. The samples were then washed repeatedly with deionized water until the pH of the filtrate was greater than or equal to 4.5. The slurry was then subjected to sonication for 10-100 minutes to produce a GO suspension. TEM and atomic force microscopy studies showed that the majority of GO sheets were monolayer graphene when the oxidation treatment exceeded 72 hours, and when the oxidation time was 48-72 hours was shown to be bilayer or trilayer graphene.

The GO sheet has an oxygen content of about 35% to 47% by weight with an oxidation treatment time of 48-96 hours. GO sheets were suspended in water. The GO suspension was cast into a thin graphene oxide thin film on a glass surface and separately slot die coated onto a PET thin film substrate, dried and peeled off from the PET substrate to form a GO thin film. The GO thin films were separately heated from room temperature to 1500 °C and then slightly roll-pressed to obtain reduced graphene oxide (RGO) thin films (free-standing layers) for use as porous graphene layers in filtration devices. .

Separately, an ultrasonic spraying procedure was performed to spray the GO aqueous solution onto the main surface of the sheet of PP-based nonwoven fabric. After drying, a fabric structure coated with a graphene layer was obtained. We observed that some of the GO sheets partially penetrated most of the PP nonwoven structure. These GO sheets were held in place by PP fibers without the use of adhesive resin.

Example 2: Preparation of pristine graphene sheets (0% oxygen) and graphene layers Pristine graphene sheets were produced by using direct sonication or liquid phase manufacturing processes. In a typical procedure, 5 grams of graphite flakes ground to a size of about 20 μm or less are added to 1000 mL of deionized water (containing 0.1 wt % dispersant, DuPont's Zonyl® FSO). Dispersed to obtain a suspension. An ultrasonic energy level of 85 W (Branson S450 Ultrasonicator) was used to exfoliate, separate and reduce the size of the graphene sheets for 15 minutes to 2 hours. The resulting graphene sheets are pristine graphene that has never been oxidized, and are oxygen-free and relatively defect-free. No other non-carbon elements.

The pristine graphene sheets were immersed in a 10 mM acetone solution of benzoyl peroxide (BPO) for 30 minutes and then removed and air-dried in air. A thermally initiated chemical reaction to functionalize the graphene sheets was performed at 80° C. in a high pressure stainless steel vessel filled with pure nitrogen. The samples were then rinsed thoroughly with acetone to remove BPO residues for subsequent Raman characterization. As the reaction time increased, a characteristic disturbance-induced D-band appeared around 1330 cm- ¹ and gradually became the most prominent feature of the Raman spectrum. The D band originates from the A _1g mode contraction vibration of the 6-membered sp ² carbocycle and becomes Raman active after the adjacent sp ² carbon atoms are converted to sp ³ hybridization. Moreover, the double-resonant 2D band near ²⁶⁷⁰ cm is greatly weakened, while the G band near ¹⁵⁸⁰ cm is attenuated due to the presence of a defect-induced D′ shoulder peak at ~ ¹⁶²⁰ cm. spread out. These observations suggest that the covalent C—C bond was converted from the sp ² configuration to the sp ³ configuration upon reaction with BPO, generating some degree of structural perturbation.

The functionalized graphene sheets were redispersed in water to produce graphene dispersions. This dispersion was then deposited on a layer of PP nonwoven to form a functionalized graphene layer coated onto the fabric using comma coating. Separately, a non-functionalized pristine graphene sheet was also coated onto the PP nonwoven layer to obtain a pristine graphene-coated fabric structure.

Example 3: Preparation of Fluorinated Graphene Sheets and Graphene Layers Several processes were used to produce GFs, but only one process is described here as an example. In a typical procedure, highly exfoliated graphite (HEG) was prepared from the intercalated compound _{C2F.xCIF3 .} HEG was further fluorinated by chlorine trifluoride vapor to produce fluorinated highly expanded graphite (FHEG). A pre-chilled Teflon reactor was charged with 20-30 mL of pre-chilled liquid CIF ₃ , the reactor was closed and cooled to liquid nitrogen temperature. Less than 1 g of HEG was then placed in a container with holes for CIF ₃ gas access and placed in the reactor. In 7-10 days, an off-white product with the approximate formula C ₂ F was formed.

Subsequently, a small amount of FHEG (about 0.5 mg) was mixed with 20-30 mL of organic solvent (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, tert-butanol, isoamyl alcohol), and A homogenous yellowish dispersion was formed when subjected to sonication (280 W) for 30 minutes. Five minutes of sonication was sufficient to obtain a relatively homogenous dispersion, but longer sonication times improved stability. After removing the solvent and extruding to form a wet film on the PET fabric surface, the dispersion became a brownish film formed on the PET fabric surface. The dry film made a good filtration member after drying and roll pressing.

Example 4: Preparation of nitrogenated graphene sheets and graphene layers Graphene oxide (GO) synthesized in Example 1 was pelletized with various ratios of urea heated in a microwave reactor (900 W) for 30 seconds. Finely ground with the mixture. The product was washed several times with deionized water and vacuum dried. In this method, graphene oxide is simultaneously reduced and doped with nitrogen. The products obtained with graphene/urea mass ratios of 1/0.5, 1/1 and 1/2 respectively contained 14.7, 18.2 and 17.5 wt% of Has a nitrogen content. These nitrogenated graphene sheets remain dispersed in water without prior chemical functionalization. The resulting suspension was wet-filmed onto a PET nonwoven layer using spray coating and then dried to form a filter member.

Example 5: Various blowing agents and pore-forming (bubble formation) processes In the field of plastics processing, chemical blowing agents are mixed into plastic pellets in powder or pellet form and melted at high temperatures. Above a certain temperature characteristic of melting the blowing agent, a gaseous reaction product (usually nitrogen or CO ₂ ) is produced which functions as the blowing agent. However, chemical blowing agents cannot be dissolved in graphene materials, which are solids rather than liquids. This presents the challenge of utilizing chemical blowing agents to create pores or cells in graphene materials.

After extensive experiments, we found that virtually any chemical blowing agent (e.g., in powder or pellet form) could be used to dry layers of graphene if the initial heat treatment temperature was sufficient to activate the blowing reaction. It has been discovered that pores or bubbles can be created. A chemical blowing agent (powder or pellets) may be dispersed in a liquid medium to become a second dispersed phase (sheets of graphene material being the first dispersed phase) within the suspension, the suspension being a solid support. It is deposited on a substrate to form a wet layer. This wet layer of graphene material may then be dried and heat treated to activate the chemical blowing agent. After the chemical blowing agent is activated and the bubbles are generated, the resulting expanded graphene structure is largely preserved even when high heat treatment temperatures are subsequently applied to the structure. This is really unexpected.

Chemical blowing agents (CFAs) can be organic or inorganic compounds that release gas upon thermal decomposition. CFA's are typically used to obtain medium to high density foams and are mostly used in combination with physical blowing agents to obtain low density foams. CFAs can be classified as either endothermic or exothermic, which refers to the type of decomposition they undergo. Endothermic types absorb energy and typically release carbon dioxide and moisture upon decomposition, while exothermic types release energy upon decomposition and typically produce nitrogen. The overall gas yield and pressure of the gas released by exothermic blowing agents is often higher than endothermic types. Endothermic CFAs are generally known to decompose in the range of 130-230°C (266-446°F), while some of the more common exothermic blowing agents decompose at 200°C (392°F). Decompose in the vicinity. However, the extent of decomposition of most exothermic CFAs can be reduced by adding certain compounds. The activation (decomposition) temperature of CFA falls within our heat treatment temperature range. Examples of suitable chemical blowing agents include sodium bicarbonate (baking soda), hydrazine, hydrazide, azodicarbonamide (exothermic chemical blowing agent), nitroso compounds (e.g. N,N-dinitrosopentamethylenetetramine), hydrazine derivatives ( Examples include 4,4′-oxybis(benzenesulfonylhydrazide) and hydrazodicarbonamide), and bicarbonates (eg, sodium bicarbonate). All of these are commercially available in the plastics industry.

In the manufacture of foamed plastics, a physical blowing agent is metered into the plastic melt during foam extrusion or injection molding foaming or supplied to one of the precursor materials during polyurethane foaming. It was not previously known that physical blowing agents could be used to create pores in solid-state (unmelted) graphene materials. Surprisingly, we found that a physical blowing agent (e.g. _CO2 or _N2 ) can be injected into the graphene suspension stream before it is coated or cast onto the supporting substrate. observed. This results in a foamed structure even when the liquid medium (eg water and/or alcohol) is removed. A dry layer of graphene material can maintain a controlled amount of pores or bubbles during liquid removal and subsequent heat treatment.

_Technically feasible _blowing agents include carbon dioxide ( _CO2 ), nitrogen ( _N2 ), isobutane ( _{C4H10 )} , cyclopentane ( _C5H10 ), isopentane ( _C5H12 ), CFC -11 (CFCI ₃ ), HCFC-22 (CHF ₂ CI), HCFC-142b (CF ₂ CICH ₃ ) and HCFC-134a (CH ₂ FCF ₃ ). However, environmental safety is a major factor to consider when choosing a blowing agent. The impact on the Montreal Protocol and the agreements it accompanies poses significant challenges for foam producers. Despite the effective properties and ease of handling of previously applied chlorofluorocarbons, there has been a global consensus to ban them due to their potential for ozone depletion (ODP). Partially halogenated chlorofluorocarbons are also environmentally unsafe and are therefore already banned in many countries. Alternatives are hydrocarbons such as isobutane and pentane and gases such as _CO2 and nitrogen.

With the exception of these restricted substances, all blowing agents mentioned above were tested in our experiments. For both physical and chemical blowing agents, the amount of blowing agent introduced into the suspension is defined as the weight ratio of blowing agent to graphene material, and the weight ratio is usually from 0/1.0 to 1.0/1.0.

Example 6: Preparation of Separate Graphene Oxide (GO) Sheets and GO Foams Chopped graphite fibers with an average diameter of 12 μm and natural graphite particles were separately used as starting materials, the starting materials being concentrated sulfuric acid, nitric acid and peroxide. A graphite intercalation compound (GIC) was prepared by soaking in a mixture of potassium manganate (as a chemical intercalate and oxidant). The starting material was first dried in a vacuum oven at 80° C. for 24 hours. A mixture of concentrated sulfuric acid, fuming nitric acid and potassium permanganate (4:1:0.05 weight ratio) was then slowly added to the three-necked flask containing the fiber segments with proper cooling and stirring. After 5-16 hours of reaction, the acid-treated graphite fibers or natural graphite particles were thoroughly filtered and washed with deionized water until the pH level of the solution reached 6. After drying overnight at 100° C., the resulting graphite intercalation compound (GIC) or graphite oxide fibers were redispersed in water and/or alcohol to form a slurry.

In one sample, 5 grams of graphite oxide fibers were mixed with 2000 ml of an alcohol solution consisting of alcohol and distilled water in a ratio of 15:85 to obtain a slurry mass. The mixed slurry was then subjected to ultrasonic irradiation at a power of 200 W for various times. After 20 minutes of ultrasonic treatment, the GO fibers were effectively exfoliated and separated into thin graphene oxide sheets with an oxygen content of about 23 wt% to 31 wt%. The resulting suspension contains GO sheets suspended in water. A chemical blowing agent (hydrazodicarbonamide) was added to the suspension just prior to casting.

The resulting suspension was then cast onto a glass surface using a doctor blade to apply shear stress and induce orientation of the GO sheets. The resulting GO coating film has a thickness that can vary from about 5-500 μm (preferably, typically 10-50 μm) after liquid removal.

To prepare the graphene foam specimens, the GO coating thin films were subjected to heat treatment, which included an initial thermal reduction temperature of 80-350°C for 0.5-2 hours, followed by a second temperature of 500-1500°C for 0.5-2 hours. It is usually accompanied by heat treatment for 5-2 hours to produce a GO foam sheet (usually 1-500 μm, but may be thinner or thicker depending on the GO coating thickness).

Example 7: Preparation of monolayer graphene sheets from mesocarbon microbeads (MCMB) and graphene foam Mesocarbon microbeads (MCMB) were obtained from China Steel Chemical Co., Kaohsiung, Taiwan. supplied from. This material has a density of about 2.24 g/cm ³ and a median particle size of about 16 μm. MCMB (10 grams) was intercalated with an acidic solution (sulfuric acid, nitric acid and potassium permanganate in a 4:1:0.05 ratio) for 48-96 hours. After the reaction was completed, the mixture was poured into deionized water and filtered. The intercalated MCMB was washed repeatedly with 5% HCl solution to remove most of the sulfate ions. The samples were then washed repeatedly with deionized water until the pH of the filtrate was greater than or equal to 4.5. The slurry was then sonicated for 10-100 minutes to produce a GO suspension. TEM and atomic force microscopy studies showed that the majority of GO sheets were monolayer graphene when the oxidation treatment exceeded 72 hours, and when the oxidation time was 48-72 hours, was shown to be bilayer or trilayer graphene.

The GO sheet contains an oxygen percentage of about 35% to 47% by weight with an oxidation treatment time of 48-96 hours. GO sheets were suspended in water. Just before casting, baking soda (5% to 20% by weight) was added to the suspension as a chemical blowing agent. The suspension was then cast onto the glass surface using a doctor blade to apply shear stress and induce the orientation of the GO sheets. Several samples were cast, some with blowing agent and some without. The resulting GO thin films can vary in thickness from about 10 μm to 500 μm after liquid removal.

Several sheets of GO thin films were then subjected to a heat treatment with an initial (first) thermal reduction temperature of 80-500° C. for 1-2 hours, with or without a blowing agent. This first heat treatment produced a graphene foam. However, if the foam is heat treated at a second temperature between 1500° C. and 2850° C., the graphene domains in the foam wall can be further perfected (re-graphitized to become more regular or by chemical fusion). , with high crystallinity and larger lateral dimensions of the graphene planes, which are longer than those of the original graphene sheets).

Example 8: Preparation of pristine graphene foam (0% oxygen). We decided to investigate whether using graphene sheets (non-oxidized and oxygen-free, non-halogenated and halogen-free, etc.) would lead to graphene foams with higher thermal conductivity. The pristine graphene sheets were produced using direct sonication or liquid phase fabrication processes.

In a typical procedure, 5 grams of graphite flakes ground to a size of about 20 μm or less are added to 1000 mL of deionized water (containing 0.1 wt % dispersant, DuPont's Zonyl® FSO). Dispersed to obtain a suspension. An ultrasonic energy level of 85 W (Branson S450 Ultrasonicator) was used to exfoliate, separate and reduce the size of the graphene sheets for 15 minutes to 2 hours. The resulting graphene sheets are unoxidized pristine graphene and are oxygen free and relatively defect free. No other non-carbon elements.

Chemical blowing agents (N,N-dinitrosopentamethylenetetramine or 4.4'-oxybis(benzenesulfonylhydrazide) in varying amounts (1 wt% to 30 wt% relative to the graphene material) were added to the pristine state. It was added to the suspension containing the graphene sheets and the surfactant, and then the suspension was cast onto the glass surface using a doctor blade to apply shear stress and induce the orientation of the graphene sheets.Just before casting. Several samples were cast, including one made using _CO2 as a physical blowing agent introduced into the suspension at 2000. The resulting graphene thin films ranged from about 10 μm to 10 μm after removal of the liquid. The thickness can be varied in the range of 100 μm.

The graphene thin film was then subjected to a heat treatment with an initial (first) thermal reduction temperature of 80-1500° C. for 1-5 hours. This first heat treatment produced a graphene foam. A portion of the pristine foam sample is then exposed to a second temperature of 1500-2850° C. to further complete the graphene domains of the foam wall (re-graphitize to become more regular or , with high crystallinity).

Example 9: CVD Graphene Foam on Ni Foam Template The procedure was described in the published literature: Chen, Z.; See other "Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapor deposition", Nat. Mater. 10, 424-428 (2011). Nickel foam, which is a porous structure with nickel interconnected 3D scaffolds, was selected as a template for graphene foam growth. Briefly, carbon was introduced into the nickel foam by decomposing _CH4 at 1000 °C under atmospheric pressure, and a graphene thin film was deposited on the surface of the nickel foam. Due to the difference in thermal expansion coefficients of nickel and graphene, ripples and wrinkles were formed in the graphene thin film. In order to recover (separate) the graphene foam, the Ni skeleton must be removed by etching. A thin layer of poly(methyl methacrylate) (PMMA) was deposited on the surface of the graphene thin film as a support before etching away the nickel framework with hot HCl (or FeCl ₃ ) solution, and the graphene network collapsed during the nickel etching. to prevent Fragile graphene foam samples were obtained after the PMMA layer was carefully removed by hot acetone. The use of a PMMA support layer is critical for preparing free-standing thin films of graphene foam; without the PMMA support layer, only severely strained and deformed graphene foam samples were obtained.

Example 10 Preparation of Graphene Oxide (GO) Suspensions from Natural Graphite and Subsequent GO Foams Graphite oxide is composed of sulfuric acid, sodium nitrate and potassium permanganate in a ratio of 4:1:0.05. were prepared by oxidizing graphite flakes at 30° C. with a oxidant solution. When natural graphite flakes (14 μm particle size) are immersion dispersed in the oxidizer mixture for 48 hours, a suspension or slurry emerges and remains optically opaque and dark. After 48 hours, the reaction mass was rinsed with water three times to adjust the pH value to at least 3.0. A final amount of water was then added to provide a series of GO water suspensions. We have observed that the GO sheets form a liquid crystal phase when the GO sheets account for a weight fraction above 3%, usually between 5% and 15%.

By dispensing and coating the GO suspension onto polyethylene terephthalate (PET) thin films with a slurry coater and removing the liquid medium from the coated thin films, we obtained dry graphene oxide thin films. Afterwards, several GO thin film samples were subjected to various heat treatments, typically including a thermal reduction treatment at a first temperature of 100°C to 500°C for 1 hour to 10 hours, and a second temperature of 1500°C to 2850°C. and thermal reduction treatment for 0.5 to 5 hours. These heat treatments transformed the GO thin films into graphene foams, also under compressive stress.

Example 11: Graphene Foam from Hydrothermally Reduced Graphene Oxide For comparison, self-assembled graphene hydrogel (SGH) samples were prepared by a one-step hydrothermal method. In a typical procedure, SGH was simply prepared by heating a 2 mg/mL homogenous graphene oxide (GO) aqueous dispersion sealed in a Teflon-lined autoclave at 180 °C for 12 h. can be done. The electrical conductivity of SGH containing about 2.6% (by weight) graphene sheets and 97.4% water is about 5×10 ⁻³ S/cm. Upon drying and heat treatment at 1500° C., the resulting graphene foam exhibits an electrical conductivity of about 1.5×10 ⁻¹ S/cm, which is comparable to the graphene foams of the present invention produced by heat treatment at the same temperature. 1/2 of the body.

Example 12: Plastic Bead Template Assisted Formation of Reduced Graphene Oxide Foams Hard template directed ordered assembly for macroporous cellular graphene thin films (MGF) was prepared. Monodisperse polymethylmethacrylate (PMMA) latex spheres were used as hard templates. GO liquid crystal prepared in Example 9 was mixed with PMMA sphere suspension. Subsequent vacuum filtration was then performed to provide an assembly of PMMA spheres and GO sheets, with GO sheets wrapped around PMMA beads. The composite film was stripped from the filter, air-dried, and fired at 800° C. to remove the PMMA template and simultaneously thermally reduce GO to RGO. The gray free-standing PMMA/GO thin films turned black after firing, while the graphene thin films remained porous. The resulting foams typically have physical densities in the range of about 0.05-0.6 g/cm ³ . The pore size can vary from meso-scale (2-50 nm) to macro-scale (a few μm) depending on the content of non-carbon elements and the amount/type of blowing agent used. This level of flexibility and versatility in designing various types of graphene foams is unprecedented and unmatched by any prior art process.

Example 13: Preparation of graphene foam from graphene fluoride We used several processes to produce GFs, but only one process is described here as an example. In a typical procedure, highly exfoliated graphite (HEG) was prepared from the intercalated compound _{C2F.xCIF3 .} HEG was further fluorinated by chlorine trifluoride vapor to produce fluorinated highly exfoliated graphite (FHEG). A pre-chilled Teflon reactor was charged with 20-30 mL of pre-chilled liquid CIF ₃ , the reactor was closed and cooled to liquid nitrogen temperature. Then, <1 g of HEG was placed in the reactor in a container with holes for CIF ₃ gas to access the reactor. In 7-10 days, an off-white product with the approximate formula C ₂ F was formed.

Subsequently, a small amount of FHEG (about 0.5 mg) was mixed with 20-30 mL of organic solvent (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, tert-butanol, isoamyl alcohol), and Under sonication (280 W) for 30 minutes, a homogenous yellowish dispersion was formed. Five minutes of sonication was sufficient to obtain a relatively homogeneous dispersion, but longer sonication times ensured better stability. After removing the solvent and casting on the glass surface, the dispersion turned into a brownish thin film formed on the glass surface. When the GF thin film was heat treated, fluorine was released as a gas and helped create pores in the thin film. In some samples, a physical blowing agent ( _N2 gas) was injected into the wet GF thin film during casting. These samples exhibit much higher pore volumes or lower foam densities. Without the use of blowing agents, the resulting graphene fluoride foams exhibit physical densities of 0.35-1.38 g/cm ³ . Densities of 0.02 to 0.35 g/cm ³ were obtained when a blowing agent was used (blowing agent/GF weight ratio 0.5/1 to 0.05/1). Typical fluorine contents are from 0.001% (HTT=2500° C.) to 4.7% (HTT=350° C.) depending on the relevant final heat treatment temperature.

Example 14: Preparation of graphene foam from nitrogenated graphene Graphene oxide (GO) synthesized in Example 6 was pelletized with various proportions of urea heated in a microwave reactor (900 W) for 30 seconds. finely ground with the mixture. The product was washed several times with deionized water and vacuum dried. In this method, graphene oxide is simultaneously reduced and doped with nitrogen. The products obtained with graphene:urea mass ratios of 1:0.5, 1:1 and 1:2 are designated as NGO-1, NGO-2 and NGO-3 respectively and the nitrogen content of these samples were 14.7, 18.2 and 17.5 wt%, respectively, as found by elemental analysis. These nitrogenated graphene sheets remain dispersible in water. The resulting suspension was then cast, dried and heat treated first at a first heat treatment temperature of 200-350°C and subsequently at a second temperature of 1500°C. The resulting nitrogenated graphene foams exhibit physical densities between 0.45 and 1.28 g/cm ³ . Typical nitrogen contents of foams are 0.01% (HTT=1500° C.) to 5.3% (HTT=350° C.) depending on the relevant final heat treatment temperature.

Example 15: Oxidation of Graphite, Thermal Expansion/Exfoliation of Oxidized Graphite, and Generation of Graphite Flakes Via Air Jet Milling Nominally 45 μm graphite powder supplied by Asbury Carbons (405 Old Main Street, Asbury, NJ 08802, USA). Natural flake graphite of size was milled to reduce its size to about 14 μm (Sample 1a). Chemicals used in this study, including fuming nitric acid (>90%), sulfuric acid (95-98%), potassium chlorate (98%) and hydrochloric acid (37%), were purchased from Sigma-Aldrich and untreated. used in Graphite oxide (GO) samples were prepared according to the following procedure.

A reaction flask containing a magnetic stir bar was charged with sulfuric acid (176 mL) and nitric acid (90 mL) and cooled by immersion in an ice bath. The acid mixture was stirred and cooled for 15 minutes and graphite (10 g) was added with vigorous stirring to avoid agglomeration. After the graphite powder was well dispersed, potassium chlorate (110 g) was slowly added over 15 minutes to avoid a sudden temperature rise. The reaction flask was loosely capped to allow gas evolution from the reaction mixture and the reaction mixture was stirred at room temperature for 24 hours. After the reaction was completed, the mixture was poured into 8 L of deionized water and filtered. GO was redispersed and washed with a 5% HCl solution to remove sulfate ions. The filtrate was intermittently tested with barium chloride to determine if sulfate ions were present. The HCl wash step was repeated until the test was negative. The GO was then washed repeatedly with deionized water until the pH of the filtrate was neutral. After the GO slurry was spray dried and stored in a vacuum oven at 60° C., it underwent free heat exfoliation (1050° C. for 2 minutes) to obtain thermally exfoliated graphite worms. The graphite worms were then exposed to light intensity air milling to produce isolated expanded graphite flakes (typically with a thickness of 15 nm to 150 nm). Expanded graphite flakes are known to carry some chemical functional groups such as -COOH, -OH and >O.

The expanded graphite flakes were then immersed in an aqueous solution of H ₂ O ₂ (30 wt%) to impart additional oxygen-containing functional groups, especially —COOH, to these graphite flakes.

Certain graphite flakes were individually exposed to ammonia, chlorine, fluorine and bromine gases to produce different functional groups including -NH ₂ , -Cl, -F and -Br, respectively.

Example 16 Preparation of Graphite Oxide (GO) Using Modified Hammers Method Graphite oxide was prepared according to the method of Hammers [U.S. Pat. No. 2,798,878, Jul. 9, 1957]. and prepared by oxidation of natural graphite flakes with potassium permanganate. In this example, we used a mixture of 22 ml of concentrated sulfuric acid, 2.8 grams of potassium permanganate and 0.5 grams of sodium nitrate for every gram of graphite. Graphite flakes were immersed in the mixed solution and the reaction time was about 1 hour at 35°C. It is important to note that potassium permanganate must be added slowly to the sulfuric acid in a well-controlled manner to avoid overheating and other safety issues. After the reaction was complete, the mixture was poured into deionized water and filtered. The samples were then washed repeatedly with deionized water until the pH of the filtrate was about 5. The slurry was spray dried and stored in a vacuum oven at 60° C. for 24 hours. Subsequently, a portion of the powder was exfoliated in a furnace preset at 950° C. for 1 minute to obtain thermally exfoliated graphite worms.

A portion of the graphite worms was poured into a home food processor and sheared for 10 minutes to obtain expanded graphite flakes. Expanded graphite flakes with an oxygen content of 6-20% were dispersed in water to form a suspension, which was spray-coated on the surface of the PP nonwoven fabric to form a filtration member.

Example 17 Oxidation and Exfoliation of Mesocarbon Microbeads (MCMB) Graphite oxide was prepared by oxidation of mesocarbon microbeads (MCMB) following the same procedure used in Example 1. MCMB microbeads are available from China Steel Chemical Co. (Taiwan). This material has a density of about 2.14 g/cm ³ , a grain size of 25 microns and an interplanar distance of about 0.336 nm. After deep oxidation treatment, the interplanar spacing of the resulting graphite oxide microbeads is about 0.76 nm. When exfoliated at 350° C. for 2 minutes, the exfoliated carbon worms have flakes with thicknesses between 3 nm and 15 nm.

A portion of the exfoliated carbon worms was then dispersed in an acidic solution (including citric acid dissolved in water) to form a slurry. This slurry was then applied to a PP nonwoven sheet and dehydrated to obtain an antiviral filtering member. This member contained citric acid dispersed on the graphite flake surface and citric acid dispersed on the PP fiber surface.

Example 18: Fluorination of Graphite to Produce Exfoliated and Expanded Graphite Fluoride Flakes 200-250 mesh sieve size natural graphite flakes were heated under vacuum (less than ^10-2 mmHg) for about 2 hours to form graphite. The residual moisture contained in was removed. Fluorine gas was introduced into the reactor and the reaction was allowed to proceed at 375° C. for 120 hours while maintaining the fluorine pressure at 200 mmHg. This was based on the procedure proposed by Watanabe et al. disclosed in US Pat. No. 4,139,474. The powder product obtained was black in color. The fluorine content of the product was measured as follows: the product was combusted according to the oxygen flask combustion method and fluorine was absorbed in water as hydrogen fluoride. The fluorine content was determined by employing a fluoride ion electrode. As a result, we obtained a GF (Sample _5A ) with the empirical formula (CF _0.75 ) _n . X-ray diffraction shows a major (002) peak at 2θ=13.5 degrees, which corresponds to an interplanar spacing of 6.25 Å. A portion of the graphite fluoride powder was thermally exfoliated to form graphite worms, which were air jet milled to obtain expanded graphite fluoride flakes. These graphite flakes were then dispersed in a polyacrylic acid (2%) aqueous solution to form a suspension, and the suspension was sprayed onto a nonwoven sheet to form an antiviral filtration member after drying the water. bottom.

Example 19 Halogenation _of Expanded Graphite Fluoride Flakes A sample of expanded graphite fluoride (CF _0.68 ) obtained in Example 4 was subjected to 1,4-dibromo-2-butene ( BrH ₂ C—CH=.CH—CH ₂ Br) vapor for 3 hours. It was found that two-thirds of the fluorine was lost from the graphite-fluoride sample. It is speculated that 1,4-dibromo-2-butene reacts positively with graphite fluoride, removing fluorine from the graphite fluoride and forming bonds to carbon atoms in the graphite lattice. The resulting product is a mixed graphite halide, possibly a combination of graphite fluoride and graphite bromide. These halogenated graphite flakes were then painted onto a sheet of meltblown PP fabric and laminated between the outer and inner layers of the fabric to form a face mask.

Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoiodine antimicrobial agents, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to the fabric or graphene sheet), sulfonamides, fluoroquinolones or combinations thereof.

In certain embodiments, the disclosed filtration member further comprises an antimicrobial compound distributed on the surface of the graphite flakes. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organic iodine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

In some embodiments, the nonwoven of the filtration member comprises polymeric fibers and the antimicrobial compound is distributed on the surface of the polymeric fibers. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organic iodine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may contain an anti-bacterial compound.

Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoiodine antimicrobial agents, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to textiles or graphite flakes), sulfonamides, fluoroquinolones, hypericin, curcumin (including polymeric curcumin), or combinations thereof. good too.

In certain embodiments, the disclosed filtration member further comprises an antimicrobial compound distributed on the surface of the graphite flakes. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organic iodine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

In some embodiments, the nonwoven fabric of the filtration member comprises polymer fibers and the antimicrobial compound is distributed on the surface of the polymer fibers. The antimicrobial compound is an antiviral selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, organic silver iodine antimicrobial agents, iodine resins, sialic acid, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. Or it may comprise an antimicrobial compound.

An antiviral or antimicrobial compound may be deposited on the graphene sheet surface or pore wall graphene surface of the graphene foam or graphite flakes. This deposition may occur before or after the graphene sheets or foams are formed into the graphene layer, or before or after the graphite flakes are formed into the layer. Antimicrobial compounds include acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoiodine antimicrobial agents, iodine resins, sialic acids (e.g., nine-carbon monosaccharides with carboxylic acid substituents on the ring), cationic groups (e.g., quaternary ammonium cationic hydrocarbon groups attached to fabric or graphene sheets), sulfonamides, fluoroquinolones, hypericin, curcumin (including polymeric curcumin), or combinations thereof. good.

Claims (82)

A face mask for use by a wearer having a face, mouth and nose, said face mask comprising:
a) a mask body configured to cover at least the mouth and nose of the wearer, the mask body having an inner side facing the wearer;
b) a fastener for holding the mask in place on the wearer's face, the fastener including a portion that engages the mask body and a portion that engages the wearer; with
the mask body comprises (i) an air permeable outer layer, (ii) an inner layer disposed inside the mask body, and (iii) a graphene layer disposed on the mask body;
The graphene layer comprises a plurality of separate monolayer or few-layer graphene sheets, and the graphene sheets include pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, iodine A face mask selected from hydrogenated graphene, hydrogenated graphene, nitrided graphene, doped graphene, chemically functionalized graphene, or combinations thereof, wherein the fastener connects the mask body to the wearer. 2. The face mask of claim 1, wherein said graphene layer is disposed between said outer layer and said inner layer. 2. The face mask of claim 1, wherein said graphene layer is embedded in said outer layer. 2. The face mask of claim 1, wherein said graphene layer is embedded in said inner layer. 2. The face mask of Claim 1, wherein the graphene sheet is chemically bonded to the surface of the mask body. 2. The face mask of claim 1, wherein said graphene sheets are chemically bonded to the surface of said mask body using an adhesive or bonding agent. The face mask according to claim 1, wherein the graphene layer has a density of 0.005-1.7 g/cm ³ and a specific surface area of 10-3200 m ² /g. The face mask according to claim 1, wherein said graphene layer has a specific surface area of 50-3000 m ² /g or a density of 0.1-1.2 g/cm ³ . 2. The face mask of claim 1, wherein said geraphen layer is a separate layer. 2. The face mask of claim 1, wherein at least one of the outer layer or the inner layer comprises a woven or non-woven construction of polymer fibers or glass fibers. 3. The face mask of claim 1, wherein the fasteners comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around one or more ears of the wearer. 2. The face mask of Claim 1, wherein the fastener comprises an elastic strap that hooks around the wearer's head. At least one of the outer layer or the inner layer is cotton, cellulose, wool, polyolefin, polyester, polyamide, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymer, water-soluble polymer. , copolymers thereof and combinations thereof. 2. The face mask of claim 1, wherein said graphene sheets have an oxygen content of 5% to 50% by weight based on the total weight of said graphene sheets. 2. The face mask of Claim 1, wherein the mask body further comprises an antimicrobial compound. The face mask according to claim 1, wherein the mask body further comprises an antimicrobial compound distributed on the surface of the graphene sheets, and the graphene sheets have a specific surface area of 50-2630 m ² /g. The antimicrobial compound is an antiviral or antimicrobial compound selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobial agents, iodine resins, sialic acid, cationic groups, sulfonamides, fluoroquinolones, or combinations thereof. 17. The face mask of claim 16, comprising: 2. A filtration material for use in the face mask of claim 1, wherein said filtration material comprises a layer of woven or non-woven fabric having two major surfaces and deposited on at least one of said two major surfaces. and a graphene layer embedded in or embedded in said woven or non-woven layer. The graphene layer may be pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, doped graphene, graphene chemically functionalized, or 19. The filtration material of claim 18, comprising a plurality of discrete single or few layers of graphene sheets selected from a combination of: 20. The filtration material of claim 19, wherein said graphene sheets are chemically bonded to at least one of said major surfaces with or without the use of adhesives or bonding agents. 20. The filtration material according to claim 19, wherein the graphene layer has a density of 0.005-1.7 g/cm ³ and a specific surface area of 10-3200 m ² /g. 20. The filtration material of claim 19, wherein the graphene layer has a specific surface area of 50-3000 m ² /g or a density of 0.1-1.2 g/cm ³ . A filtering device comprising the filtering material according to claim 18 as a filtering member. 24. The filtration device of claim 23, which is a water purification device, an air cleaning device, a solvent removal device or an oil recovery device. 19. A process for manufacturing the filtration material of claim 18, the process comprising the steps of: (a) providing a layer of woven or non-woven fabric having two major surfaces; depositing a graphene layer on at least one of the major surfaces. (b) dispersing discrete graphene sheets in a gaseous medium with or without an adhesive to form a flowing fluid; and allowing the graphene sheets to adhere to the at least one major surface. (b) dispersing discrete graphene sheets in a liquid medium with or without an adhesive to form a slurry; and depositing said slurry on at least one of said two major surfaces. 26. The process of claim 25, comprising the steps of: allowing to form a wet graphene layer; and removing or drying the liquid medium from the wet graphene layer to form the graphene layer. 28. The process of Claim 27, wherein said depositing step comprises a procedure selected from casting, coating, spraying, printing, brushing, painting or combinations thereof. It is a roll-to-roll process comprising the steps of (a) (i) providing a roll of woven or non-woven fabric; and (ii) continuous lengths of sheets of said fabric (mounted on rollers or reels). (iii) depositing a graphene layer on at least one of the two major surfaces to form a graphene layer coated fabric; 26. The process of claim 25, comprising iv) collecting the graphene layer coated fabric on a take-up roller. 26. The process of claim 25, further comprising incorporating the filtering material into a mask body fitted with fasteners to form the face mask. A face mask for use by a wearer having a face, mouth and nose, said face mask comprising:
(c) a mask body configured to cover at least the wearer's mouth and nose;
(d) a fastener for holding the mask in place on the wearer's face, the fastener including a portion that engages the mask body and a portion that engages the wearer; , and
the mask body comprises (i) an air permeable outer layer, (ii) an inner layer disposed inside the mask body, and (iii) a layer of graphene foam disposed within the mask body; A face mask, wherein the fastener connects the mask body to the wearer. 32. The face mask of Claim 31, wherein said graphene foam layer is disposed between said outer layer and said inner layer. 32. The face mask of claim 31, wherein said graphene foam layer is embedded in said outer layer. 32. The face mask of claim 31, wherein said graphene foam layer is embedded in said inner layer. The graphene foam layers include pristine graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, doped graphene, and chemically functionalized. 32. The face mask of claim 31, comprising a graphene material selected from graphene or combinations thereof. 32. The face mask of Claim 31, wherein the graphene foam layer is chemically bonded to the surface of the mask body using an adhesive or bonding agent. 32. The face mask according to claim 31, wherein said graphene foam layer has a density of 0.005-1.0 g/cm ³ or a specific surface area of 40-2600 m ² /g. 32. The face mask according to claim 31, wherein said graphene foam layer has a specific surface area of 200-2000 m ² /g or a density of 0.01-0.5 g/cm ³ . 32. The face mask of claim 31, wherein said graphene foam layer is a separate layer. 32. The face mask of claim 31, wherein at least one of the outer layer or the inner layer comprises a woven or non-woven construction of polymer fibers or glass fibers. The fasteners comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around the wearer's ears, or hook around the wearer's head. 32. The face mask of claim 31, comprising elastic straps. The outer layer or the inner layer may be made of cotton, cellulose, wool, polyolefin, polyester, polyamide, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymers, water-soluble polymers, copolymers thereof and 32. The face mask of claim 31, comprising polymeric fibers selected from the group of combinations thereof. 32. The face mask of claim 31, wherein said graphene foam layer has an oxygen content of 5% to 50% by weight based on the total weight of said graphene sheet. 32. The face mask of claim 31, wherein said mask body further comprises an antimicrobial compound. 32. The face mask of claim 31, wherein the mask body further comprises an antimicrobial compound distributed on pore wall surfaces of the graphene foam layer. The antimicrobial compound is an antiviral or antimicrobial compound selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobial agents, iodine resins, sialic acid, cationic groups, sulfonamides, fluoroquinolones, or combinations thereof. 46. The face mask of claim 45, comprising: 32. A filtering member for use in a face mask according to claim 31, said filtering member comprising a layer of woven or non-woven fabric having two major surfaces and a layer of fabric deposited on at least one of said two major surfaces. and a layer of graphene foam embedded in or embedded in said woven or non-woven layer. 48. The filtration member of claim 47, wherein said graphene foam layer is chemically bonded to at least one of said major surfaces using an adhesive or bonding agent. 48. The filtration member according to claim 47, wherein the graphene foam layer has a density of 0.005-1.0 g/cm ³ or a specific surface area of 40-2600 m ² /g. 48. The filtration member of claim 47, wherein the graphene foam layer has a specific surface area of 200-2000 m ² /g or a density of 0.01-0.5 g/cm ³ . 38. A filtering device comprising the filtering member according to claim 37 as a filtering member. 52. The filtration device of claim 51, which is a water purification device, an air cleaning device, a solvent removal device or an oil recovery device. A filtration member for use in a filtration device, said filtration member comprising a layer of an air permeable membrane having two major surfaces and a layer of air permeable membrane deposited on at least one of said two major surfaces or said air a layer of chemically functionalized graphite flakes embedded in the layer of permeable membrane, said graphite flakes being a non-hydrogen selected from O, N, H, F, Cl, Br, I or combinations thereof. A filtration member comprising chemical functional groups containing 1% to 50% by weight of elemental carbon. 54. The filtration member of claim 53, wherein the air permeable membrane is selected from a woven or nonwoven sheet, a porous polymer membrane, an open cell foam strip, a breathable paper sheet, or combinations thereof. 54. The filtration member of claim 53, wherein the layer of graphite flakes is chemically bonded to at least one of the major surfaces using an adhesive or bonding agent. 54. A filtration member according to claim 53, wherein the layer of graphite flakes has a specific surface area of 10-500 m ² /g. Said nonwovens are made of cotton, cellulose, wool, polyolefins, polyesters, polyamides, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymers, water-soluble polymers, copolymers thereof and combinations thereof. 55. The filtration member of claim 54, comprising polymeric fibers selected from the group of 54. The filtering member of claim 53, further comprising an antimicrobial compound distributed on the surface of said graphite flakes. 55. The filtration member of claim 54, wherein said nonwoven fabric comprises polymer fibers and an antimicrobial compound distributed on the surface of said polymer fibers. The antimicrobial compound is an antimicrobial selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. 59. The filtering member of claim 58, comprising a virus or antimicrobial compound. The antimicrobial compound is an antimicrobial selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. 60. The filtering member of claim 59, comprising a virus or antimicrobial compound. 54. A filtering device comprising the filtering member of claim 53. 63. The filtration device of claim 62, which is a water purification device, an air cleaning device, a solvent removal device or an oil recovery device. 63. The filtering device of claim 62, which is a face mask. A face mask for use by a wearer having a face, mouth and nose, said face mask comprising:
(e) a mask body configured to cover at least the wearer's mouth and nose;
(f) a fastener for holding the mask in place on the wearer's face, the fastener including a portion that engages the mask body and a portion that engages the wearer; , and
3. The mask body comprises: (i) an air permeable outer layer; (ii) an inner layer disposed inside the mask body; and (iii) the filtration member of claim 1 disposed within the mask body. A face mask comprising: 66. The face mask of claim 65, wherein said filtering member is positioned between said outer layer and said inner layer. 66. The face mask of claim 65, wherein said filtering member is embedded in said outer layer. 66. The face mask of claim 65, wherein said filtering member is embedded in said inner layer. The fasteners comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around the wearer's ears, or hook around the wearer's head. 66. The face mask of claim 65, comprising elastic straps. A face mask for use by a wearer having a face, mouth and nose, said face mask comprising:
A) a mask body configured to cover at least the wearer's mouth and nose;
B) a fastener for holding the mask in place on the wearer's face, the fastener including a portion that engages the mask body and a portion that engages the wearer; with
The mask body comprises (i) an air permeable outer layer, (ii) an inner layer disposed inside the mask body, and (iii) a layer of chemically functionalized graphite flakes disposed on the mask body. and wherein the graphite flakes comprise chemical functional groups containing 1% to 50% by weight of non-carbon elements selected from O, N, H, F, Cl, Br, I, or combinations thereof; face mask. 71. The face mask of claim 70, wherein said filtering member is positioned between said outer layer and said inner layer. 71. The face mask of claim 70, wherein said filtering member is embedded in said outer layer. 71. The face mask of claim 70, wherein said filtering member is embedded in said inner layer. A face mask comprising graphite flakes chemically functionalized as an antimicrobial agent, said graphite flakes containing 1 weight of a non-carbon element selected from O, N, H, F, Cl, Br, I or combinations thereof. A face mask comprising chemical functional groups containing % to 50% by weight. 71. The face mask of claim 70, wherein the layer of chemically functionalized graphite flakes is chemically bonded to the surface of the outer layer or the surface of the inner layer using an adhesive or bonding agent. 71. A face mask according to claim 70, wherein the layer of chemically functionalized graphite flakes has a specific surface area of 10-500 m ² /g. 71. The face mask of claim 70, wherein the outer layer or the inner layer comprises a woven or non-woven structure of polymeric or glass fibers, a porous polymeric membrane, a breathable sheet of paper, or a combination thereof. The fasteners comprise a pair of ear straps extending from opposite sides of the mask body and configured to hook around the wearer's ears or hook around the wearer's head. 71. The face mask of claim 70, comprising elastic straps. The outer layer or the inner layer may be made of cotton, cellulose, wool, polyolefin, polyester, polyamide, rayon, polyacrylonitrile, cellulose acetate, polystyrene, polyvinyl, poly(carboxylic acid), biodegradable polymers, water-soluble polymers, copolymers thereof and 71. The face mask of claim 70, comprising polymeric fibers selected from the group of combinations thereof. 71. The face mask of claim 70, wherein said mask body further comprises an antimicrobial compound. 71. The face mask of claim 70, wherein said mask body comprises an antimicrobial compound distributed on the surface of said graphite flakes. The antimicrobial compound is an antimicrobial selected from acrylic acid, methacrylic acid, citric acid, acidic polymers, silver organoidine antimicrobial agents, iodine resins, sialic acids, cationic groups, sulfonamides, fluoroquinolones, hypericin, curcumin, or combinations thereof. 71. The face mask of Claim 70, comprising a virus or antimicrobial compound.

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