JP7030788B2 - Conductive foams and devices derived from humic acid - Google Patents

Description

Cross-reference to related applications This application is for US Patent Application No. 15 / 251,841 filed August 30, 2016, and US Patent Application No. 15 / 251,849 filed August 30, 2016. Claims priority over the issue (which is incorporated herein by reference).

The present invention generally relates to the field of carbon / graphite foams, and more particularly to the production of novel forms of humic acid-derived conductive foams, devices containing such humic acid-derived foams, and devices thereof. Regarding the method for.

Carbon has five unique crystal structures such as diamond, fullerene (0D nanographite material), carbon nanotube or carbon nanofiber (1D nanographite material), graphene (2D nanographite material), and graphite (3D graphite material). It is known to have. All these materials can be made into foam structures.

Carbon nanotubes (CNTs) mean tubular structures grown to have a single or multi-layered structure. Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have diameters on the order of nanometers to hundreds of nanometers. Their longitudinal hollow structures give the material unique mechanical, electrical and chemical properties. CNTs or CNFs are one-dimensional nanocarbon or one-dimensional nanographite materials. However, CNTs are difficult to manufacture and extremely expensive. In addition, CNTs are known to be difficult to disperse in solvents or water, and difficult to mix with other materials. These properties severely limit their scope of application.

The single-layer graphene sheet is composed of carbon atoms that occupy a two-dimensional hexagonal lattice. Multi-layer graphene is a plate lit composed of two or more graphene surfaces. The individual single-layer graphene sheets and multi-layer graphene plate lit are collectively referred to herein as nanographene plate lit (NGP) or graphene material. NGP contains pure graphene (essentially 99% carbon atom), slightly oxidized graphene (<5% by weight oxygen), and graphene oxide (≧ 5% by weight oxygen).

NGPs have been found to have a wide range of extraordinary physical, chemical, and mechanical properties. Our research group first discovered graphene [B. Z. Jang and W. C. Huang, "Nano-scaled Graphene Plates", US Patent Application No. 10 / 274,473, filed October 21, 2002; now US Pat. No. 7,071,258 (07/04). / 2006)]. Methods for producing NGP and NGP nanocomposites have been previously investigated by us [Bor Z. Jang and A Zhamu, "Processing of Nano Graphene Platelets (NGPs) and NGP Nanocomposites: A Review," J. Mol. Materials Sci. 43 (2008) 5092-5101]. NGP was manufactured according to four major prior art methods. Their advantages and disadvantages are briefly summarized as follows:

Method 1: Chemical formation and reduction of graphene oxide (GO) In the first method (FIG. 1), natural graphite powder is treated with intercalant and oxidants (eg, concentrated sulfuric acid and nitric acid, respectively) to form a graphite intercalation compound (eg, concentrated graphite and nitric acid, respectively). GIC) or, in fact, a step of obtaining graphite oxide (GO) is required. [William S. Hummers, Jr. , Et al. , Preparation of Graphite Oxide, Journal of the American Chemical Society, 1958, p. 1339. ] Prior to intercalation or oxidation, graphite has a graphene interplanetary spacing of approximately 0.335 nm (L _d = 1 / 2d ₀₀₂ = 0.335 nm). Intercalation and oxidation treatment typically increase the inter-graphene spacing to a value greater than 0.6 nm. This is the first expansion step that the graphite material undergoes during this chemical pathway. The resulting GIC or GO is then subjected to additional expansion (often exfoliation) using either thermal shock exposure or solution-based sonication-assisted graphene layer exfoliation methods. It is offered to).

In the method of exposure to thermal shock, GIC or GO is exposed to a high temperature (typically 800 to 1,050 ° C.) for a short period of time (typically 15 to 60 minutes) to exfoliate or expand the GIC or GO. To form exfoliated or further expanded graphite, which is typically in the form of a "graphite worm" composed of graphite flakes that are still interconnected with each other. This thermal shock procedure may result in some separated graphite flakes or graphene sheets, but usually most of the graphite flakes remain interconnected. Typically, the exfoliated graphite or graphite worm is then subjected to a flake separation process using air milling, mechanical shearing, or sonication in water. Therefore, Method 1 basically requires three distinct procedures: first swelling (oxidation or intercalation), further swelling (or "peeling"), and separation.

In a solution-based separation method, the swollen or exfoliated GO powder is dispersed in water or an aqueous alcohol solution and subjected to sonication. In these methods, ultrasound after intercalation and oxidation of graphite (ie, after the first expansion) and typically after exposure of the resulting GIC or GO to thermal shock (after the second expansion). It is important to note that the process is used. Alternatively, the GO powder dispersed in water can be ion-exchanged or very long purified so that the repulsive force between the ions present in the interplanar voids overcomes the inter-graphene van der Waals force s and results in the separation of the graphene layer. To serve.

There are some major problems with this traditional chemical manufacturing process:
(1) The process requires the use of large amounts of some unwanted chemicals such as sulfuric acid, nitric acid, and potassium permanganate or sodium chlorate.
(2) The chemical treatment process typically requires long intercalation and oxidation times of 5 hours to 5 days.
(3) Strong acids consume a significant amount of graphite during this long intercalation or oxidation process by "progressing as they erode graphite" (converting graphite to carbon dioxide, which is lost in the process). ). It is not uncommon to lose 20-50% by weight of graphite material soaked in strong acids and oxidants.
(4) Thermal delamination requires high temperatures (typically 800-1,200 ° C.) and is therefore a highly energy intensive process.
(5) Both the thermal stripping method and the solution stripping method require very time-consuming, lengthy cleaning and purification steps. For example, typically washing with 2.5 kg of water to recover 1 gram of GIC yields a very large amount of wastewater that needs to be properly treated.
(6) In both the thermal and solution exfoliation methods, the resulting product is a GO plate lit that must undergo an additional chemical reduction treatment to reduce the oxygen content. Typically, even after reduction, the electrical conductivity of GO plate lit remains much lower than that of pure graphene. In addition, reduction procedures often require the use of toxic chemicals such as hydrazine.
(7) Further, the amount of intercalation solution retained on the flakes after drainage ranges from 20 to 150 parts by weight (pph) of solution per 100 parts by weight of graphite flakes and more typically from about 50 to 120 pph. There may be. Residual intercalate species retained by flakes during hot exfoliation decompose to produce various species of sulfur and nitrite compounds (eg NO _x and SO _x ), which are not desirable. Waste liquid requires costly improvement procedures to avoid adverse environmental impacts.

Method 2: Direct formation of pure nanographene platelits In 2002, our research team conducted single-layer and multi-layer graphene sheets from partially carbonized or graphitized polymer carbons obtained from polymers or pitch precursors. Was successfully isolated [B. Z. Jang and W. C. Huang, "Nano-scaled Graphene Plates", US Patent Application No. 10 / 274,473, filed October 21, 2002, now US Pat. No. 7,071,258 (07/04) / 2006)]. Mack, etal [“Chemical manual of nanostructured materials” US Pat. No. 6,872,330 (March 29, 2005)] describes a step of intercalating graphite with a potassium melt and the resulting K. Has developed a method that requires a step of contacting the intercalated graphite with alcohol and a step of producing severely stripped graphite containing NGP. This method must be done carefully in a vacuum or in an extremely dry glove box environment, as high-purity alkali metals such as potassium and sodium are extremely sensitive to moisture and are at risk of explosion. This process is not suitable for mass production of NGP.

Method 3: Epitaxy Growth and Chemical Vapor Deposition of Nanographene Sheets on Inorganic Crystal Surfaces Small-scale production of ultrathin graphene sheets on substrates can be obtained by pyrolysis epitaxial growth and laser desorption / ionization techniques. [Walt A. DeHeer, Claire Berger, Phillip N. First, "Patterned thin film gravity devices and meter for making same" US Pat. No. 7,327,000 B2 (June 12, 2003)] Graphite epitaxial film having only one or a small number of atomic layers Due to their unique properties and great potential as device substrates, they are technically and scientifically important. However, these methods are not suitable for mass production of isolated graphene sheets for composite materials and energy storage applications.

Another method for producing graphene in the form of thin films (typically <2 nm thick) is catalytic chemical vapor deposition. This catalytic CVD requires catalytic decomposition of a hydrocarbon gas (eg C ₂ H ₄ ) on a Ni or Cu surface to form single-layer or multi-layer graphene. When Ni or Cu is the catalyst, the carbon atoms obtained by the decomposition of hydrocarbon gas molecules at a temperature of 800-1,000 ° C. are either deposited directly on the Cu foil surface or from the Ni—C solid solution state to Ni. It precipitates on the surface of the foil to form a sheet of single-layer or multi-layer graphene (less than 5 layers). The Ni or Cu catalytic CVD method is not suitable for the deposition of more than 5 graphene surfaces (typically <2 nm) beyond which the underlying Ni or Cu layer can no longer provide any catalytic effect. CVD graphene film is extremely expensive.

Method 4: Bottom-up method (synthesis of graphene from small molecules)
Yang, et al. ["Two-dimensional Graphene Nano-ribbons," J.M. Am. Chem. Soc. 130 (2008) 4216-17] is 12 nm using a method starting with the Suzuki-Miyaura coupling of 1,4-diiodot-2,3,5,6-tetraphenyl-benzene and 4-bromophenylboronic acid. Nanographene sheets with lengths up to were synthesized. The obtained hexaphenylbenzene derivative was further derivatized and fused into a small graphene sheet. This is a slow method of making very small graphene sheets so far.

Therefore, there is a need to have a new class of carbon nanomaterials that are as good as or better than graphene in terms of properties but more cost effective, faster, more scalable, and can be manufactured in a more environmentally friendly way. ing. Manufacturing processes for such novel carbon nanomaterials reduce the amount of unwanted chemicals (or remove them all together), reduce process time, reduce energy consumption, and are undesirable. Requires reduction or removal of effluent into the drainage channel of chemical species (eg, sulfuric acid) or into the air (eg, SO ₂ and NO ₂ ). Moreover, it would be nice if this new nanomaterial could easily be made into a foam structure that is relatively thermally and electrically conductive.

Generally speaking, a foam or foam material is composed of pores (or cells) and pore walls (solid material). As an example, the pores can be interconnected to form open cell foam. Graphene foam is composed of pores and pore walls containing graphene material. There are three main methods of producing graphene foam, all of which are monotonous, energy intensive and time consuming:

The first method is to seal the graphene oxide (GO) aqueous suspension in a high pressure autoclave and the GO suspension under high pressure (tens or hundreds of atmospheres), typically at 180-300 ° C. Hydrothermal reduction of graphene oxide hydrogels, which typically requires a step of heating over a long period of time (typically 12-36 hours) at a temperature in the range. Useful references for this method are presented here: Y. Xu, et al. , "Self-Assembled Graphene Hydrogel via a One-Step Hydrothermal Process" ACS Nano 2010, 4, 4324-4330. There are some major problems with this problem: (a) High pressure requirements make it an impractical method for industrial scale manufacturing. For one thing, this method cannot be performed continuously. (B) It is difficult, if not impossible, to control the pore diameter and porosity level of the resulting porous structure. (C) It is inflexible in terms of varying the shape and size of the resulting reduced graphene oxide (RGO) material (eg, it cannot be made into a film shape). (D) This method requires the use of ultra-low concentrations of GO suspended in water (eg 2 mg / mL = 2 g / L = 2 kg / kL). With the removal of non-carbon elements (up to 50%), less than 2 kg of graphene material (RGO) / 1000 liter suspension can only be produced. Moreover, it is virtually impossible to operate a 1000 liter reactor that must withstand high temperature and high pressure conditions. Obviously, this is not a scalable method for mass production of porous graphene structures.

The second method is based on a template-assisted catalytic CVD method, which requires a CVD deposition of graphene on a sacrificial template (eg, Ni foam). The graphene material matches the shape and dimensions of the Ni foam structure. Therefore, an etching agent is used to remove the Ni foam by etching, leaving behind a monolith of graphene skeleton, which is essentially an open cell foam. Useful references for this method are presented here: Zongping Chen, et al. , "Three-dimensional flexible and connected intensive graphene networks green by chemical vapor deposition," Nature24,10.10. There are some problems with such methods: (a) Catalyzed CVD is essentially a very slow, highly energy intensive and costly method. (B) The etching agent is typically a highly undesirable chemical and the resulting Ni-containing etching solution is a source of contamination. Recovering or recirculating the melted Ni metal from the etchant solution is very difficult and costly. (C) Maintaining the shape and dimensions of graphene foam without damaging the cell wall when the Ni foam is removed by etching is a challenge. The resulting graphene foam is typically very brittle and fragile. (D) Transport of CVD precursor gas (eg, hydrocarbons) inside the metal foam can be difficult and non-uniform because certain locations within the sacrificial metal foam may not be accessible to the CVD precursor gas. Structure may result.

Also, a third method of producing graphene foam utilizes a sacrificial material (eg, colloidal polystyrene particles, PS) coated with a graphene oxide sheet using a self-assembling method. For example, Choi et al. Produced chemically modified graphene (CMG) paper in two steps: self-sustaining PS by vacuum filtration of a mixed aqueous colloidal suspension of CMG and PS (2.0 μm PS spheres). / CMG film is produced and then the PS beads are removed to create 3D macropores. [B. G. Choi, et al. , "3D Macropores Graphene Frameworks for Supercapacitors with High Energy and Power Dentishes," ACS Nano, 6 (2012) 4020-4028. Choi et al. Produced aligned self-contained PS / CMG paper by filtration, which began by separately preparing a negatively charged CMG colloidal suspension and a positively charged PS suspension. A mixture of CMG colloid suspension and PS suspension was dispersed in solution under controlled pH (= 2), where the two compounds had the same surface charge (+13 ± 2.4 mV for CMG). And for PS, the zeta potential value of +68 ± 5.6 mV). When the pH rises to 6, CMG (Zeta potential = -29 ± 3.7 mV) and PS spheres (Zeta potential = + 51 ± 2.5 mV) are collected due to the electrostatic interaction and hydrophobic properties between them. These were then integrated into the PS / CMG composite paper by a filtration process. This method also has some drawbacks: (a) This method requires very time consuming chemical treatment of both graphene oxide and PS particles. (B) Removal of PS with toluene also results in a weakened macroporous structure. (C) Toluene is a highly regulated chemical and must be treated with great care. (D) The pore size is typically excessively large (eg, a few μm) and is too large for many useful applications.

The above considerations clearly show that any prior art method or process for producing graphene and graphene foam has major imperfections. Accordingly, it is an object of the present invention to provide a new class of foam material that is thermally and electrically conductive and mechanically tough, and to provide a cost effective method of producing this class of foam. be.

Humic acid (HA) is an organic substance commonly found in soil and can be extracted from soil using a base (eg KOH). HA can also be extracted in high yield from a type of coal called leonaldite, another highly oxidized form of lignite coal. HA extracted from leonaldite contains a large number of oxygenating groups (eg, carboxyl groups) located around the edges of a molecular center (SP ² core of hexagonal carbon structure) such as graphene. This material is a bit like graphene oxide (GO) produced by strong acid oxidation of natural graphite. HA has a typical oxygen content of 5% to 42% by weight (other major elements are carbon and hydrogen). HA has an oxygen content of 0.01% by weight to 5% by weight after chemical or thermal reduction. For the definition of claims in the present application, humic acid (HA) is based on the entire range of oxygen content of 0.01% by weight to 42% by weight. Reduced humic acid (RHA) is a special type of HA with an oxygen content of 0.01% by weight to 5% by weight.

The present invention is directed to a new class of graphene-like 2D materials (ie, humic acid) that can be surprisingly converted into highly structurally integrated foamed structures. Therefore, another object is to provide a cost effective method for producing such nanocarbon foams (specifically, humic acid-derived foams) in large quantities. This method does not require the use of non-environmentally friendly chemicals. This method allows for flexible design and allows control of porosity level and pore size.

Another object of the present invention is to provide a humic acid-derived foam exhibiting thermal conductivity, electric conductivity, elastic modulus, and / or strength equal to or higher than that of conventional graphite foam, carbon foam, or graphene foam. Is. Yet another object of the present invention is to provide a humic acid-derived foam preferably having a mesoscale pore size range (2-50 nm).

Another object of the present invention is to provide a product (eg, a device) containing the humic acid-derived foam of the present invention and a method for operating these products.

The present invention provides a humic acid-derived foam composed of a plurality of pores and pore walls, the pore walls containing a single-layer or multi-layer humic acid-derived hexagonal carbon sheet, and a multi-layer hexagonal carbon sheet. Has 2 to 10 laminated hexagonal carbon atomic planes with an interplane spacing d ₀₀₂ of 0.3354 nm to 0.60 nm (preferably 0.40 nm or less) as measured by X-ray diffraction. The single-layer or multi-layer hexagonal carbon sheet contains 0.01% by weight to 25% by weight of non-carbon elements. Humic acid (HA) is humic acid oxide, reduced humic acid, fluorinated humic acid, chlorinated humic acid, brominated humic acid, humic acid iodide, hydrided humic acid, nitrogenized humic acid, dope tohumic acid, chemical. It is selected from humic acid functionalized in, or a combination thereof.

The fumic acid-derived foams invented herein can be divided into three types: (a) at least 10% by weight (typically 10% to 42% by weight) of non-carbon elements that can be used for a wide range of applications. And most typically 10% -25%) of fumic acid (HA) foam, where the original fumic acid molecules remain substantially the same, but some chemical linkage occurs between the HA molecules), ( b) Chemically assimilated, reduced fumic acid-based foam, where extensive ligation and assimilation between the original HA molecules occurs to form the initial graphene hexagonal carbon sheet that constitutes the pore wall, initially Causes the generation of chemical species containing non-carbon elements attached to HA molecules (thus, non-carbon element content is generally reduced between 2% by weight and 10% by weight), and (c) essence. Fumic acid-derived graphite foam containing only carbon (<2% by weight, preferably <1%, more preferably <0.1%), where the pore walls are hexagonal carbon atoms. Contains a single layer or several layers (2-10) graphene-like sheets that are faces.

Preferably and typically, HA-derived foams have a density of 0.005 to 1.7 g / cm ³ , a specific surface area of 50 to 3,200 m ² / g, a thermal conductivity of at least 100 W / mK per unit specific weight, and / Or has an electric conductivity of 500 S / cm or more per unit specific surface area. More typically, the humic acid-derived foam has a density of 0.01-1.5 g / cm ³ or an average pore diameter of 2 nm-50 nm. In embodiments, the foam has a specific surface area of 200-2,000 m ² / g or a density of 0.1-1.3 g / cm ³ .

Typically, when the HA-derived foam is produced from a method that does not include a heat treatment temperature (HTT) above 300 ° C., the foam has a non-carbon element content in the range of 10% to 42% by weight. The pore walls can still contain identifiable humic acid molecules, which are sheet-like hexagonal carbon atomic structures. Non-carbon elements can include elements selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron. In certain embodiments, the pore walls contain fluorinated humic acid and the foam contains a fluorinated content of 0.01% to 25% by weight. In another embodiment, the foam contains an oxygen content of 0.01% to 25% by weight.

Using HTTs above 300 ° C., the close-packed and well-aligned adjacent HA molecules are chemically linked together to form a multi-ring aromatic that resembles an early graphene-like hexagonal carbon atomic structure. Structures can be formed. As the heat treatment continues, these highly aromatic molecules are assimilated together in an edge-to-edge manner, increasing the length and width of the graphene-like hexagonal planes, while at the same time several hexagonal carbon planes together. It can be laminated to form a multi-layer carbon atomic structure similar to a multi-layer graphene structure. The interplane spacing is typically reduced to << 0.60 nm, more typically <0.40 nm. When the HTT is from 300 ° C to 1,500 ° C, it is typically chemically assimilated to produce a foam based on reduced humic acid, where extensive linkage and assimilation between the original HA molecules occurs. , Form an early graphene-like hexagonal carbon sheet that constitutes the pore wall. The non-carbon content in the foam is typically reduced to 2% -10%.

When the HTT is between 1,500 ° C and 3,200 ° C, the foam can be essentially graphite foam, where the pore walls contain single or multi-layer graphene-like hexagonal carbon planes and are non-carbon. The content is reduced to less than 2% by weight.

In a preferred embodiment, the foam is in the form of a continuous length roll sheet having a thickness of 200 μm or less and a length of at least 1 meter, preferably at least 2 meters, more preferably at least 10 meters, most preferably at least 100 meters. Manufactured into (continuous foam sheet rolls). This sheet roll is manufactured by the roll-to-roll method. There was no prior art HA-derived graphene-like foam manufactured in the form of sheet rolls.

In a preferred embodiment, the HA-derived foam has an oxygen or non-carbon content of less than 1% by weight and the pore walls are laminated graphene-like surfaces with interplane spacing of less than 0.35 nm, at least per unit weight. It has a thermal conductivity of 200 W / mK and / or an electrical conductivity of 1,000 S / cm or more per unit specific weight.

In a more preferred embodiment, the HA-derived foam has an oxygen content or non-carbon content of less than 0.1% by weight, and the pore walls are laminated graphene-like hexagons with interplane spacing of less than 0.34 nm. It contains a carbon atomic surface, a thermal conductivity of at least 250 W / mK per unit specific gravity, and / or an electrical conductivity of at least 1,500 S / cm per unit specific gravity.

In yet another preferred embodiment, graphene foam has an oxygen content or non-carbon content of 0.01% by weight or less, and the pore walls are laminated graphene with spacing between graphenes of less than 0.336 nm. It has a surface, a mosaic spread value of 0.7 or less, a thermal conductivity of at least 300 W / mK per unit specific weight, and / or an electrical conductivity of 2,000 S / cm or more per unit specific weight.

In yet another preferred embodiment, the graphene foam has a pore wall containing laminated graphene-like hexagonal carbon atomic planes with interplane spacing of less than 0.336 nm, a mosaic spread value of 0.4 or less, and 400 W per unit weight. It has a thermal conductivity of over / mK and / or an electrical conductivity of over 4,000 S / cm per unit weight.

In a preferred embodiment, the pore wall has a laminated graphene-like hexagonal carbon atomic plane with an interplane spacing of less than 0.337 nm and a mosaic spread value of less than 1.0. In a preferred embodiment, the foam exhibits a graphitization degree of 80% or higher (preferably 90% or higher) and / or a mosaic spread value of less than 0.4. In a preferred embodiment, the pore walls contain a three-dimensional network structure of interconnected graphene-like hexagonal carbon atom planes.

In a preferred embodiment, the solid foam contains mesoscale pores with a pore size of 2 nm to 50 nm. Also, solid foams can be made to contain micron-scale pores (1-500 μm).

In the HA-derived foam of the present invention, (a) humic acid is oxidized humic acid, reduced humic acid, and fluorinated humic acid in the step of preparing a humic acid dispersion in which a plurality of humic acid molecules or sheets are dispersed in a liquid medium. A dispersion selected from acid, chlorinated humic acid, brominated humic acid, iodide humic acid, hydride humic acid, nitrogenized humic acid, doped humic acid, chemically functionalized humic acid, or a combination thereof. A step of containing an optional foaming agent having a foaming agent to humic acid weight ratio of 0 / 1.0 to 1.0 / 1.0, and (b) a substrate supporting the graphene dispersion (for example, a plastic film). , Rubber sheet, metal foil, glass sheet, paper sheet, etc.) to form a wet layer of humic acid by distributing and depositing on the surface, and (c) partially or a liquid medium from the wet layer of humic acid. The step of completely removing to form a dried layer of humic acid and (d) the dried layer of humic acid are non-carbon elements (eg O, H, N, B, F, Cl, Br, I). Heat treatment at a first heat treatment temperature of 80 ° C. to 3,200 ° C. at a desired heating rate sufficient to induce the formation and release of volatile gas molecules from (etc.) or to activate the effervescent agent. It may be produced by a method including a step of producing a humic acid-derived foam. Preferably, the partitioning and deposition procedure comprises subjecting the humic acid dispersion to an orientation-induced stress.

The HA material contains 5% by weight or more of non-carbon elements (for example, O, H, N, B, F, Cl, Br, I, etc.) (preferably 10% or more, more preferably 20% or more, still more preferably. 30%), this optional foaming agent is not required. Subsequent high temperature treatments help remove most of these non-carbon elements from the edges of the HA molecules and produce volatile gas species that produce pores or cells within the solid foam structure. In other words, very surprisingly, these non-carbon elements act as foaming agents. Therefore, the externally added foaming agent is optional (not required). However, the use of foaming agents can provide additional flexibility in adjusting or adjusting the level of porosity and pore size for the desired application. If the non-carbon element content in humic acid is less than 5%, a foaming agent is typically required.

The foaming agent can be a physical foaming agent, a chemical foaming agent, a mixture thereof, a dissolving and leaching agent, or a mechanically introduced foaming agent.

The method may further include the step of heat treating the solid foam at a second heat treatment temperature higher than the first heat treatment temperature for a time sufficient to obtain the graphene-like foam, wherein the pore walls are 0. It contains a laminated hexagonal carbon atomic plane with an interplane spacing d ₀₀₂ of 3354 nm to 0.40 nm and a content of less than 5% by weight (typically 0.001% to 2%) of non-carbon elements. When the obtained non-carbon element content is 0.1% to 2.0%, the interplanar spacing d ₀₀₂ is typically 0.337 nm to 0.40 nm.

If the original HA molecule in the dispersion contains a non-carbon element content greater than 5% by weight, the hexagonal carbon atomic plane in the solid foam (after heat treatment) will be during the heat treatment step (d). Contains structural defects that occur in. The liquid medium can simply be water and / or alcohol, but it is environmentally friendly.

In a preferred embodiment, the method is such that steps (b) and (c) supply the supporting substrate from the feeder roller to the deposition area and the HA dispersion continuously or discontinuously on the surface of the supporting substrate. A step of forming a wet layer of HA material on it, a step of drying a wet layer of HA material to form a dried layer of HA material, and a step of forming a dry layer of HA material on the supporting substrate. It is a roll-to-roll method including a step of collecting the dried layers of the above on a collector roller. Such a roll-to-roll or reel-to-reel method is a truly industrial-scale, large-scale manufacturing method that can be automated.

In one embodiment, the first heat treatment temperature is 100 ° C to 1,500 ° C. In another embodiment, the second heat treatment temperature is at least (A) 300 to 1,500 ° C., (B) 1,500 to 2,100 ° C., and / or (C) 2,100 to 3, A temperature selected from 200 ° C. is included. In certain embodiments, the second heat treatment temperature includes a temperature in the range of 300 to 1,500 ° C. for at least 1 hour and then a temperature in the range of 1,500 to 3,200 ° C. for at least 1 hour. included.

There are some surprising results of performing the first and / or second heat treatment on the dried HA layer, which can achieve different purposes with different heat treatment temperature ranges, eg (a) HA material. Removes non-carbon elements from (eg, heat-reduces fluorinated fumic acid to give reduced fumic acid) to produce volatile gas, creating pores or cells in HA foam, (b) chemistry. Activate target or physical foaming agents to produce pores or cells, (c) chemically link or assimilate fumic acid molecules to highly aromatic molecules and edge-to-edge aromatic ring structures or hexagonal carbon planes. Assimilate to significantly increase the lateral dimensions (length and width) of the graphene hexagonal carbon sheet within the foam wall (solid portion of foam), (d) naturally present in HA or fumin Recovery of defects that occur during fluorination, oxidation, or nitridation of acid molecules, and (e) reorganization and completion of graphite domains or crystals. These different purposes or functions are achieved to different degrees within different temperature ranges. Non-carbon elements typically include elements selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron. Very surprisingly, even under low temperature foaming conditions, heat treatments are often chemical linkages, assimilation, or chemical bonds between sheet HA molecules in an edge-to-edge manner (some in a face-to-face manner). cause.

In one embodiment, the HA-derived foam has a specific surface area of 200-2,000 m ² / g. In one embodiment, the solid foam has a density of 0.1-1.5 g / cm ³ . In the embodiment, the step (d) of heat-treating the layer of graphene material at the first heat treatment temperature is performed under compressive stress. In another embodiment, the method comprises a compression step that reduces the level of film thickness, pore size, or porosity of the HA-derived foam. In some applications, the foam has a thickness of 200 μm or less.

In embodiments, the HA dispersion has at least 5% by weight of HA dispersed in the liquid medium and forms a liquid crystal phase. In embodiments, the first heat treatment temperature comprises a temperature in the range of 80 ° C to 300 ° C, resulting in HA foam having an oxygen content or non-carbon element content of less than 5% and a pore wall. , Interplane spacing less than 0.40 nm, thermal conductivity of at least 150 W / mK (more typically at least 200 W / mk) per unit specific weight, and / or electrical conductivity of at least 1,000 S / cm per unit specific weight. Have.

In a preferred embodiment, the first and / or second heat treatment temperature comprises a temperature in the range of 300 ° C to 1,500 ° C, and as a result, the HA-derived foam contains less than 2% oxygen or non-carbon. With a quantity, the pore walls have an interplanetary spacing of less than 0.35 nm, a thermal conductivity of at least 250 W / mK per unit density, and / or an electrical conductivity of at least 1,500 S / cm per unit density.

When the first and / or second heat treatment temperature comprises a temperature in the range of 1,500 ° C to 2,100 ° C, the HA-derived foam has an oxygen content or non-carbon content of less than 1%. The pore walls have a spacing between graphenes less than 0.34 nm, a thermal conductivity of at least 300 W / mK per unit density, and / or an electrical conductivity of 3,000 S / cm or more per unit density.

When the first and / or second heat treatment temperature comprises a temperature above 2,100 ° C., the HA-derived foam has an oxygen content or non-carbon content of 0.1% or less and the pore walls , Interplane spacing of less than 0.336 nm, mosaic spread value of 0.7 or less, thermal conductivity of at least 350 W / mK per unit weight, and / or electrical conductivity of 3,500 S / cm or more per unit weight.

When the first and / or second heat treatment temperature comprises a temperature of 2,500 ° C. or higher, the HA-derived foam contains pores containing laminated graphene-like hexagonal carbon planes with interplane spacing of less than 0.336 nm. It has a wall, a mosaic spread value of 0.4 or less, and a thermal conductivity of> 400 W / mK per unit weight and / or an electrical conductivity of> 4,000 S / cm per unit density.

In one embodiment, the pore wall has a laminated graphene-like hexagonal carbon plane with an interplane spacing of less than 0.337 nm and a mosaic spread value of less than 1.0. In another embodiment, the solid wall portion of the HA-derived foam exhibits a graphitization degree of 80% or higher and / or a mosaic spread value of less than 0.4. In yet another embodiment, the solid wall portion of the HA-derived foam exhibits a graphitization degree of 90% or higher and / or a mosaic spread value of 0.4 or lower.

Typically, after heat treatment at HTT above 2,500 ° C., the pore walls within the HA-derived graphite foam contain a three-dimensional network structure of interconnected hexagonal carbon atom planes that are electron conduction paths. The cell wall is 20 nm or more, more typically and preferably 40 nm or more, even more typically and preferably 100 nm or more, even more typically and preferably 500 nm or more, often greater than 1 μm, and sometimes greater than 10 μm. Contains graphite domains or graphite crystals having the lateral dimensions ( _La , length or width) of. Graphite domains typically have a thickness of 1 nm to 20 nm, more typically 1 nm to 10 nm, and even more typically 1 nm to 4 nm.

Preferably, the HA-derived foam contains mesoscale pores with a pore diameter of 2 nm to 50 nm (preferably 2 nm to 25 nm).

In a preferred embodiment, the present invention provides a roll-to-roll method for producing a solid HA foam or HA-derived foam composed of a plurality of pores and pore walls. In this method, (a) in the step of preparing a humic acid dispersion in which a plurality of humic acid molecules or sheets are dispersed in a liquid medium, humic acid is oxidized humic acid, reduced humic acid, fluorinated humic acid, and chlorinated. The dispersion is selected from humic acid, brominated humic acid, iodide humic acid, hydride humic acid, nitrated humic acid, doped humic acid, chemically functionalized humic acid, or a combination thereof, and the dispersion is 0 /. Steps containing an optional foaming agent having a foaming agent to humic acid weight ratio of 1.0 to 1.0 / 1.0 and (b) the HA dispersion continuously or continuously on the surface of the supporting substrate. In the process of discontinuously distributing and depositing to form a wet layer of HA material, the supporting substrate is a continuous thin film supplied from a feeder roller and collected on a collector roller, and (c) humic acid. Partially or completely removing the liquid medium from the wet layer of humic acid to form a dry layer of humic acid in the heated region or multiple heated regions, and (d) foaming the dried layer of humic acid. Heat treatment is performed in one of these heating regions containing a heating temperature of 80 ° C. to 500 ° C. at a desired heating rate sufficient to activate the agent to a density of 0.01 to 1.7 g / cm ³ or 50. Includes a step of producing a humic acid-derived foam having a specific surface area of ~ 3,000 m ² / g. In this method, the heat treatment is performed in situ during the roll-to-roll procedure. This is a very cost effective method suitable for mass production of HA-derived graphite foam sheets that are easy to ship and handle and then wound on rollers for easy cutting and slitching.

The orientation-induced stress may be shear stress. As an example, shear stress can occur as simple as a "doctor blade" that induces the diffusion of HA dispersions on a plastic or glass surface at a sufficiently high shear rate during a manual casting process. .. As another example, a "knife-on-roll" configuration produces an orientation-induced stress that is effective in an automated roll-to-roll coating method that distributes a graphene dispersion over a moving solid substrate such as a plastic film. The relative motion between this moving film and the coating knife acts to result in the orientation of the graphene sheet along the direction of shear stress. Comma coating and slot die coating are particularly effective methods for this function.

Shear stress can align HA molecules or sheets along a particular direction (eg, X-direction or length-direction) to produce a favorable orientation, and between HA molecules or sheets along the foam wall. Due to the surprising observation that contact can be facilitated, this orientation-induced stress is a crucial step in the production of HA-derived foams of the present invention. Even more surprisingly, these favorable orientations and improved contact between HAs facilitate chemical assimilation or linkage between HA molecules or sheets during subsequent heat treatment of the dried HA layer. Such favorable orientation and improved contact are essential for the final achievement of the very high thermal conductivity, electrical conductivity, modulus, and mechanical strength of the resulting HA-derived foam. In general, these great properties cannot be achieved without the control of orientation induced by such shear stresses.

The present invention also provides an oil removing or oil separating device containing humic acid-derived foam as an oil absorbing element. Also provided are solvent removal or solvent separation devices containing humic acid-derived foam as a solvent absorption or solvent separation element.

The present invention also provides a method for separating oil from water. The methods include (a) providing an oil absorbing element containing a foam derived from complete fumic acid, (b) contacting the oil-water mixture with an element that absorbs oil from the mixture, and (c) element from the mixture. It includes a step of taking out and extracting the oil from the element, and (d) a step of reusing the element.

Furthermore, the present invention provides a method of separating an organic solvent from a solvent-water mixture or from a multi-solvent mixture. The method comprises (a) providing an organic solvent absorbing or solvent separating element comprising a foam derived from complete fumic acid, and (b) using the element with an organic solvent-water mixture, or with a first solvent and at least a second solvent. A step of contacting the mixture with a plurality of solvents contained therein, a step of allowing the element to absorb the organic solvent from the mixture, or a step of separating the first solvent from at least the second solvent, and (d). It comprises the steps of removing the element from the mixture and extracting the organic solvent or the first solvent from the element, and (e) reusing the element.

Also provided are heat management devices containing humic acid-derived foam as a heat diffusion or heat dissipation element. The heat management device is selected from heat exchangers, heat sinks, heat pipes, high conductive inserts, conductive plates between heat sinks and heat sources, heat diffusion components, heat dissipation components, thermal interface media, or thermoelectric or Pelche cooling devices. Devices may be provided.

FIG. 1 is a schematic diagram illustrating a method for producing a graphene sheet from natural graphite particles. FIG. 2 shows the possible mechanisms of chemical linkage and assimilation between humic acid molecules and between “linked HA molecules”. Two or three original HA molecules can be chemically linked together to form a longer or wider HA molecule called a "linked HA molecule". Multiple "linkage HA molecules" can be assimilated to form graphene-like hexagonal carbon atom planes. FIG. 3A is a value-to-weight ratio of thermal conductivity of HA-derived foam, mesophase pitch-derived graphite foam, and Ni foam template-assisted CVD graphene foam produced by the method of the present invention. FIG. 3B shows the thermal conductivity values of HA-derived foam, GO foam templated with sacrificial plastic beads, and hydrothermally reduced GO graphene foam. FIG. 4 is data on the electrical conductivity of the HA-derived foam and the hydrothermally reduced GO graphene foam produced by the method of the present invention. FIG. 5 is the thermal conductivity value of the foam sample obtained from HA and fluorinated HA, plotted as a function of specific gravity. FIG. 6 is the thermal conductivity value of the foam sample obtained from HA and pure graphene as a function of the final (highest) heat treatment temperature. FIG. 7 is plotted as a function of the oxygen content in the foam where the amount of oil absorbed per gram of HA-derived foam has a porosity level of about 98% (separation of oil from oil-water mixture). FIG. 8 is the amount of oil absorbed per gram of monolithic HA-derived foam, plotted as a function of porosity level (assuming the same oxygen content is given). FIG. 9 is the amount of chloroform absorbed from the chloroform-water mixture, plotted as a function of degree of fluorination. FIG. 10 is a schematic diagram of a heat sink structure (two embodiments).

Humic acid (HA) is an organic substance commonly found in soil and can be extracted from soil using a base (eg KOH). HA can also be extracted from a type of coal called leonaldite, another highly oxidized form of lignite coal. HA extracted from leonaldite contains a large number of oxygenating groups (eg, carboxyl groups) located around the edges of a molecular center (SP ² core of hexagonal carbon structure) such as graphene. This material is a bit like graphene oxide (GO) produced by strong acid oxidation of natural graphite. HA has a typical oxygen content of 5% to 42% by weight (other major elements are carbon, hydrogen, and nitrogen). Examples of the molecular structure of humic acid with various components such as quinones, phenols, catechols and sugar moieties are shown in Scheme 1 below (Source: Stevenson F.J. "Humus Chemistry: Genesis, Combination, Reactions,""John Willy & Sons, New York 1994).

Non-aqueous solvents for fumic acid include polyethylene glycol, ethylene glycol, propylene glycol, alcohols, sugar alcohols, polyglycerols, glycol ethers, amine solvents, amide solvents, alkylene carbonates, organic acids, or inorganic acids. Is done.

The present invention provides a humic acid-derived foam composed of a plurality of pores and pore walls and a method for producing the same foam. Sheet-like humic acid molecules are (1) chemically linked / assimilated together (edge-to-edge and / or face-to-face) typically at a temperature of 100 to 1,500 ° C. and / or (2) high temperature (2). Organizes into larger graphite crystals or domains along the pore walls (typically> 2,100 ° C. and more typically> 2,500 ° C.) (referred to herein as regraphitization). During or after the formation of pores in the foam.

Further, according to the present invention, (a) in the step of preparing a humic acid dispersion in which a plurality of humic acid molecules or sheets are dispersed in a liquid medium, humic acid is humic acid oxide, reduced humic acid, or fluorinated humic acid. A dispersion can be selected from chlorinated humic acid, brominated humic acid, iodide humic acid, hydride humic acid, nitrogenized humic acid, doped humic acid, chemically functionalized humic acid, or a combination thereof. A step of containing an optional foaming agent having a foaming agent to humic acid weight ratio of 0 / 1.0 to 1.0 / 1.0, and (b) a substrate supporting the graphene dispersion (for example, plastic film, rubber). The steps of distributing and depositing on the surface of a sheet, metal foil, glass sheet, paper sheet, etc.) to form a wet layer of humic acid, and (c) partially or completely remove the liquid medium from the wet layer of humic acid. The step of removing the dried layer of humic acid to form a dried layer of humic acid, and (d) the dried layer of humic acid with volatile gas molecules as non-carbon elements (eg, O, H, N, B, F, Cl, A humic acid-derived foam is produced by heat-treating at a first heat treatment temperature of 80 ° C. to 3,200 ° C. at a desired heating rate sufficient to derive from Br, I, etc.) or to activate the effervescent agent. Provided is a manufacturing method including a process. Preferably, the partitioning and deposition procedure comprises subjecting the humic acid dispersion to an orientation-induced stress. These non-carbon elements produce volatile gases that act as forming agents or foaming agents when removed by heat-induced decomposition.

The resulting fumic acid-derived foam is typically 0.005-1.7 g / cm ³ (more typically 0.01-1.5 g / cm ³ and even more typically 0.1-1.0 g). / Cm ³ , most typically 0.2-0.75 g / cm ³ ), or 50-3,000 m ² / g (more typically 200-2,000 m ² / g, most typically 500). It has a specific surface area of ~ 1,500 m ² / g).

Foaming agents or forming agents are substances that can form cells or foamed structures by foaming methods in a variety of materials that undergo solidification or phase transition, such as polymers (plastics and rubbers), glass, and metals. They are typically applied when the material to be foamed is in a liquid state. It has not been previously known that foaming agents can be used to make foaming materials while in the solid state. More importantly, no teaching or suggestion has been made so far that aggregates of humic acid can be converted into graphene-like foams by foaming agents. Cell structures in the base metal are typically made to reduce density and increase heat resistance and sound insulation while increasing the thickness and relative stiffness of the original polymer.

Foaming agents or related foaming mechanisms that create pores or cells (air bubbles) in the matrix to produce foamed or cellular materials can be classified into the following groups:
(A) Physical foaming agents: eg hydrocarbons (eg pentane, isopentane, cyclopentane), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and liquid CO ₂ . The bubble / foam manufacturing process is endothermic, i.e. it requires heat (eg from chemical heat generation due to a melting process or cross-linking) to vaporize the liquid foaming agent.
(B) Chemical foaming agents: eg isocyanates, azo-, hydrazines and other nitrogen-based materials (for thermoplastic and elastomer foams), sodium bicarbonate (used in thermoplastic foams, eg baking soda). Here gas products and other by-products are formed by chemical reactions and are facilitated by the process or by the exotherm of the reactive polymer. Since the blowing reaction requires a step of forming a low molecular weight compound that acts as a blown gas, additional heat generation is also generated. Powdered titanium hydride is used as a forming agent in the production of metal foam, which decomposes to form titanium and hydrogen gas at high temperatures. Zirconium hydride (II) is used for the same purpose. Once formed, the low molecular weight compound never reverts to the original foaming agent, i.e. the reaction is irreversible.
(C) Mixed Physical / Chemical Foaming Agents: Used, for example, to produce flexible polyurethane (PU) foams with very low densities. Both chemical and physical blowing are used in series to offset each other against the heat energy released / absorbed; thus minimizing the temperature rise. For example, in the production of very low density flexible PU foams for mattresses, isocyanates and water (reacting to form CO ₂ ) are combined with liquid CO ₂ (boiling to produce a gaseous form).
(D) Mechanically Infused Agents: Mechanically produced foams require a method of introducing air bubbles into a liquid polymerizable base material (eg, an unvulcanized elastomer in the form of a liquid latex). Methods include whipping air or other gas or low boiling volatile liquids in a low viscosity lattice, or injecting gas into an extruder barrel or die, or into an injection molded barrel or nozzle, and screw shearing. / Includes the step of uniformly dispersing the gas by mixing action to form a very fine bubble or gas solution in the melt. When the melt is molded or extruded and the work piece is at atmospheric pressure, the gas exits the solution and causes the polymer melt to expand shortly before solidification.
(E) Soluble and leachable agents: Soluble fillers, for example solid sodium chloride crystals mixed in a liquid urethane system, which are then shaped into solid polymer processed products, where sodium chloride is used to form solid molded products for some time. It is later washed and removed by immersion in water, leaving small interconnect holes in the relatively dense polymer product.
(F) We have found that all of the above five mechanisms can be used to create pores in HA-derived materials while in the solid state. Another mechanism for producing pores in HA materials is by generating and vaporizing volatile gases by removing those non-carbon elements in a high temperature environment. This is a unique self-foaming method that has never been taught or suggested.

The pore walls (cell walls) in the foam of the present invention contain chemically bonded and assimilated graphene-like hexagonal carbon atomic planes. These planar aromatic molecules or hexagonal carbon atoms are fully interconnected physically and chemically. The lateral dimensions (length or width) of these surfaces are very large (20 nm to> 10 μm), typically several times or even orders of magnitude larger than the maximum length / width of the starting humic acid molecule. Hexagonal carbon atomic planes are essentially interconnected to form long electron conduction paths with low resistance. This is a unique and novel class of material that has not been previously discovered, developed, or perhaps suggested to exist.

In step (b), the HA suspension is formed into a wet layer on the surface of a solid substrate (eg PET film or glass), preferably under the influence of shear stress. An example of such a shearing procedure is the casting or coating of a thin film of HA suspension using a coating machine. This procedure resembles a layer of varnish, paint, coating, or ink coated on a solid substrate. Rollers, "doctor blades", or wipers can generate shear stress when the film is formed at a sufficiently high relative motion rate or when there is relative motion between the roller / blade / wiper and the supporting substrate. .. Quite unexpectedly and importantly, such shearing action allows planar HA molecules to be well aligned, for example, along the shear direction. Even more surprising, such molecules when the liquid component in the HA suspension is subsequently removed to form a fully packed layer of highly aligned sheet-like HA molecules that are at least partially dried. Alignment or preferred orientation is not broken. The dried HA film has a high birefringence coefficient between the direction in the plane and the direction perpendicular to the plane.

In embodiments, the HA layer is then thermally treated to activate the foaming agent and / or remove non-carbon elements (eg F, O, etc.) from the HA molecule to produce a volatile gas as a by-product. It is used for the induced reaction. These volatile gases create pores or bubbles in the solid HA material and push sheet-like HA molecules into the wall structure to form HA foam. When no foaming agent is added, the non-carbon elements in the HA material preferably make up at least 10% by weight (preferably at least 20%, more preferably at least 30%) of the HA material. The first (initial) heat treatment temperature is typically> 80 ° C, preferably> 100 ° C, more preferably> 300 ° C, even more preferably> 500 ° C, and can be as high as 1,500 ° C. The foaming agent is typically activated at a temperature of 80 ° C to 300 ° C, but can be higher. The forming procedure (formation of pores, cells, or bubbles) is typically completed within the temperature range of 80-1,500 ° C. Very surprisingly, chemical ligation or assimilation between hexagonal carbon atom planes in edge-to-edge and plane-to-plane methods (FIG. 2) is only at relatively low heat treatment temperatures (eg 150-300 ° C.). ) Can occur.

The HA-derived foam may be subjected to further heat treatment requiring at least a second temperature significantly higher than the first heat treatment temperature.

A well-programmed heat treatment procedure is simply a single heat treatment temperature (eg, only the first heat treatment temperature), at least two heat treatment temperatures (a first temperature for a period of time, then a second temperature, and then an additional temperature. A heat treatment temperature (maintaining at this second temperature for another period of time), or a heat treatment temperature including an initial treatment temperature (first temperature) and a final HTT (second temperature) higher than the first temperature. Any other combination of HTT) can be included. The highest or final HTT received by the dried HA layer may be divided into four different HTT regimes:

Regime 1 (80 ° C to 300 ° C): Illustrated in the upper part of FIG. 2 in this temperature range (chemical linkage and heat reduction regime and, if present, activation regime for foaming agents). As such, the HA layer first undergoes heat-induced chemical linkage of adjacent HA molecules. This also requires the removal of certain non-carbon atoms such as O and H, typically resulting in a reduction in oxygen content from 20-42% (of O in HA) to about 10-25%. This process reduces the interplanetary spacing within the foam wall from about 0.6-1.2 nm (when dried) to about 0.4-0.6 nm, and heats up to 100 W / mK per unit weight. It results in an increase in conductivity and / or an increase in electrical conductivity up to 2,000 S / cm per unit weight. (The level of porosity of the graphene foam material, and therefore the density, can be varied, and given the same graphene material, both thermal and electrical conductivity values change with the density, so these characteristic values It must be separated by specific gravity to aid in fair comparison.) Even with such a low temperature range, some chemical ligation between HA molecules occurs. The interplane spacing remains relatively large (0.4 nm and above). Many O-containing functional groups remain (eg, -OH and -COOH).

Regime 2 (300 ° C to 1,500 ° C): In this chemical linkage and assimilation regime, extensive compounding, polymerization, and cross-linking between adjacent HA molecules or linked HA molecules, as shown in the lower part of FIG. It arises to form an early graphene-like hexagonal carbon atom plane. Oxygen content is typically reduced to 2% to 10% (eg after chemical ligation and assimilation), resulting in a reduction in interplanetary spacing to about 0.345 nm. Some initial graphitization is such a low temperature, in sharp contrast to conventional graphitizable materials (such as polyimide carbide films) that typically require temperatures as high as 2,500 ° C to initiate graphitization. This means that it has already begun in. This is another distinct feature of the graphene foam of the present invention and its manufacturing process. These chemical linkage reactions result in an increase in thermal conductivity up to 250 W / mK per unit specific density and / or an increase in electrical conductivity up to 2,500 to 4,000 S / cm per unit specific gravity.

Regime 3 (1,500-2,500 ° C.): In this ordering and graphitization regime, a significantly improved degree of structural ordering within the foam wall where extensive graphitization or graphene-like surface assimilation occurs. Bring. As a result, the oxygen content is typically reduced to 0.1-2% and the spacing between graphenes is reduced to about 0.337 nm (1% to about 80% graphite depending on the actual HTT and time). Achieve the degree of conversion). Also, the improved degree of order is reflected by an increase in thermal conductivity up to> 350 W / mK per unit density and / or an increase in electrical conductivity up to> 3,500 S / cm per unit density.

Regime 4 (higher than 2,500 ° C): Extensive migration and removal of grain boundaries and other defects in this recrystallization and complete regime, several orders of magnitude larger than the original grain size of the HA molecule. The result is the formation of near-complete single or polycrystalline graphene-like crystals with very large grains within the foam walls. The oxygen content is essentially eliminated, typically 0% to 0.01%. The interplanetary spacing is reduced to about 0.3354 nm (80% to almost 100% graphitization), which corresponds to the complete graphitization of a graphite single crystal. The foamed structure thus obtained exhibits a thermal conductivity of> 400 W / mK per unit specific gravity and an electric conductivity of> 4,000 S / cm per unit specific gravity.

The HA-derived foam structures of the present invention are more generally the first, spanning at least the first regime, which typically requires 1 to 4 hours in this temperature range if the temperature never exceeds 500 ° C. Over two regimes (preferably 1-2 hours), and more generally the first three regimes (preferably 0.5-2.0 hours in regime 3), and all four regimes (0.2). It can be obtained by heat-treating the dried HA using a temperature program that can be carried out over (may be carried out to achieve the highest conductivity), including regime 4 for ~ 1 hour.

The X-ray diffraction pattern was obtained using an X-ray diffractometer equipped with CuKcv radiation. Diffraction peak shifts and widening were calibrated using a silicon powder standard. Graphitization degree, g is the formula d ₀₀₂ = 0.3354 g + 0.344 (1-g) of mailing (in the formula, d ₀₀₂ is the interval between intermediate layers of graphite or graphene type crystals in nm units). Was calculated from the X-ray pattern using. This equation is valid only when d ₀₀₂ is about 0.3440 nm or less. Graphene foam walls with d ₀₀₂ above 0.3440 nm act as spacers to increase the interplanetary spacing of oxygen-containing functional groups (eg, -OH,> O, and on the surface or edges of the graphene-like molecular plane). -Reflects the presence of (COOH, etc.).

Another structural index that can be used to characterize the degree of ordering of the laminated and bonded hexagonal carbon atom planes of HA-derived graphene-like and conventional graphite crystals in the foam wall is the locking of the (002) or (004) reflections. It is a "mosaic spread" represented by the half-value full width of a curve (X-ray diffraction intensity). This degree of order characterizes the graphite or graphene crystal size (or grain size), the amount of grain boundaries and other defects, and the preferred degree of grain orientation. A nearly perfect single crystal of graphite is characterized by having a mosaic spread value of 0.2-0.4. Most of our graphene walls have a mosaic spread value in this range of 0.2-0.4 (if manufactured using a heat treatment temperature (HTT) of 2,500 ° C or higher). However, some values range from 0.4 to 0.7 when the HTT is between 1,500 and 2,500 ° C, and 0.7 when the HTT is between 300 and 1,500 ° C. It is in the range of ~ 1.0.

Explained in FIG. 2 is a reasonable chemical linkage and assimilation mechanism, in which only two aligned HA molecule segments are shown as an example, but many HA molecules are chemically linked together. Multiple "linkage HA molecules" can be chemically assimilated to form a foam wall. In addition, for HA molecules or sheets, chemical linkages can also be made edge-to-edge as well as face-to-face. It can occur. These ligation and assimilation reactions proceed so that the molecules are chemically assimilated, linked and integrated into a single entity. The resulting product is not a simple assembly of single HA sheets. It is a single entity that is essentially a network structure of interconnected macromolecules with essentially innumerable molecular weights. All constituent hexagonal carbon planes are very large in lateral dimensions (length and width) and have an HTT. If high enough (eg> 1,500 ° C or higher), these surfaces are essentially bonded together.

In-depth studies using combinations of SEM, TEM, selected area diffraction, X-ray diffraction, AFM, Raman spectroscopy, and FTIR have shown that HA-derived foam walls have several very large hexagonal carbon atomic planes (typically). It is shown to be composed of >> 20 nm, more typically >> 100 nm, often >> 1 μm, and often >> 10 μm, or even >> 100 μm in length / width). When the final heat treatment temperature is lower than 2,500 ° C, these giant graphene-like surfaces are often in the thickness direction (c-axis) not only by van der Waals forces (as in conventional graphite crystallites) but also by covalent bonds. It is laminated and bonded along the crystal direction). In these cases, although not limited by theory, Raman and FTIR spectroscopy studies have shown that sp ² (dominant) and sp ³ (weak but present) as well as conventional sp ² in graphite. It seems to indicate the coexistence of electron configurations.

(1) This HA-derived foam wall is not manufactured by adhering or adhering discrete flakes / plate lits using resin binders, linkers, or adhesives. Instead, HA molecules are assimilated by bonding or forming covalent bonds with each other into integrated graphene-like crystalline entities without the use of any externally added linker or binder molecules or polymers.

(2) This foam wall is typically a polycrystal composed of large crystal grains with incomplete grain boundaries. This entity is obtained from multiple HA molecules, and these aromatic HA molecules have lost their original nature. When the liquid component is removed from the suspension, the resulting HA molecules form an essentially amorphous structure. During heat treatment, these HA molecules are chemically assimilated and linked to the simple substances or monolithic graphite entities that make up the foam wall. This foam wall is highly ordered.

(3) Due to these unique chemical compositions (including oxygen or non-carbon content), morphology, crystal structure (including interplane spacing), and structural features (eg, high orientation, slight defects, imperfections). No grain boundaries, no gaps between chemical bonds and graphene sheets, and few interruptions in the hexagonal carbon plane), HA-derived foams have significant thermal conductivity, electrical conductivity, mechanical strength, and rigidity ( It has a unique combination of (elasticity).

It may be further pointed out that when the non-carbon element content (H and O) is 2-20% by weight, the pore walls of the humic acid-derived foam can be given a particular desired degree of hydrophilicity. Let's go. These features allow the oil to be separated from the water by selectively absorbing the oil from the oil-water mixture. In other words, such HA-derived foam materials can recover oil from water and help cleanse rivers, lakes, or seas where oil has spilled. Oil absorption is typically 50% to 500% of the weight of the foam itself. This is a wonderfully useful material for environmental protection purposes.

If high electrical or thermal conductivity is desired, the HA-carbon foam can be subjected to graphitization at temperatures above 2,500 ° C. The resulting material is particularly useful for thermal management applications (eg, for use in making finned heat sinks, heat exchangers, or heat spreaders).

It may be pointed out that the HA-carbon foam may be subjected to compression during and / or after the graphitization process. This work makes it possible to adjust the orientation and porosity of the graphene sheet.

To characterize the structure of the graphite material produced, the X-ray diffraction pattern was obtained using an X-ray diffractometer equipped with CuKcv radiation. Diffraction peak shifts and widening were calibrated using a silicon powder standard. Graphitization degree, g uses the formula d ₀₀₂ = 0.3354 g + 0.344 (1-g) of mailing (in the formula, d ₀₀₂ is the intermediate layer spacing of graphite or graphene crystals in nm units). Then, it was calculated from the X-ray pattern. This equation is valid only when d ₀₀₂ is about 0.3440 nm or less. In this study, graphene-like (HA or RHA) foam walls with d ₀₀₂ above 0.3440 nm act as spacers to increase the spacing between graphenes (eg, the surface of the graphene molecular plane or Reflects the presence of -OH,> O, and -COOH, etc. on the edge.

Another structural index that can be used to characterize the degree of ordering of the laminated and bonded RHA surfaces in the foam wall of graphene and conventional graphite crystals is the locking curve of the (002) or (004) reflection (X-ray diffraction intensity). ) Is a "mosaic spread" represented by the full width at half maximum. This degree of order characterizes the graphite or graphene crystal size (or grain size), the amount of grain boundaries and other defects, and the preferred degree of grain orientation. A nearly perfect single crystal of graphite is characterized by having a mosaic spread value of 0.2-0.4. Most of our RHA walls have a mosaic spread value in this range of 0.2-0.4 (if manufactured using a heat treatment temperature (HTT) of 2,500 ° C or higher). However, some values range from 0.4 to 0.7 when the HTT is between 1,500 and 2,500 ° C, and 0.7 when the HTT is between 300 and 1,500 ° C. It is in the range of ~ 1.0.

In-depth studies using a combination of SEM, TEM, selected area diffraction, X-ray diffraction, AFM, Raman spectroscopy, and FTIR have shown that the fumic acid-carbon foam wall has several large graphene surfaces (typically >> 20 nm). , More typically >> 100 nm, often >> 1 μm, and often >> 10 μm in length / width). This is quite unexpected as the lateral dimensions (length and width) of the original humic acid sheet or molecule are typically <20 nm and more typically <10 nm before heat treatment. This means that multiple HA sheets or molecules can be covalently assimilated to each other from edge to edge to form larger (longer or wider) sheets.

When the final heat treatment temperature is below 2,500 ° C, these large graphene-like surfaces are also often in the thickness direction (c) by covalent bonds as well as by van der Waals forces (as in conventional graphite crystallites). Can be laminated and bonded along the axial crystallographic direction). In these cases, although not limited by theory, Raman and FTIR spectroscopy studies have shown that sp ² (dominant) and sp ³ (weak but present) as well as conventional sp ² in graphite. It seems to indicate the coexistence of electron configurations.

The one-piece HA-derived foam is composed of multiple pores and pore walls, where the pore walls contain a single-layer or multi-layer HA sheet that is chemically bonded together, where the multi-layer HA sheet is X. A single-layer or multi-layer graphene-like HA sheet has 2 to 10 layers of laminated graphene-like assimilated HA surfaces with an interplanetary spacing d ₀₀₂ of 0.3354 nm to 0.36 nm as measured by linear diffraction. It contains 0.01% to 25% by weight of non-carbon elements (more typically <15%).

The one-piece HA-derived foam typically has a density of 0.001 to 1.7 g / cm ³ , a specific surface area of 50 to 3,000 m ² / g, a thermal conductivity of at least 200 W / mK per unit specific weight, and / or a unit. It has an electric conductivity of 2,000 S / cm or more per specific surface area. In a preferred embodiment, the pore wall contains a laminated graphene-like RHA surface with an interplane spacing d ₀₀₂ of 0.3354 nm to 0.40 nm as measured by X-ray diffraction.

Many of the HA sheets can be covalently assimilated with each other from edge to edge to form an integrated reduced HA (RHA) entity. These unique chemical compositions (including oxygen or hydrogen content, etc.), morphology, crystal structure (including interplane spacing), and structural features (eg, orientation, slight defects, chemical bonds and gaps between graphene-like sheets). Due to the lack of, and few interruptions along the hexagonal plane direction), HA-derived foams have a unique combination of significant thermal conductivity, electrical conductivity, mechanical strength, and rigidity (elasticity). Have.

Thermal management applications The aforementioned features and properties make the integrated HA-derived foam an ideal element for a wide range of engineering and medical applications. For example, the foam can be used in the following applications for thermal management purposes only:
a) HA-derived foam is compressible and has high thermal conductivity, making it ideal for use as a thermal interface material (TIM) that can be introduced between a heat source and a heat spreader or between a heat source and a heat sink. Suitable for
b) The HA-derived foam can be used as it is as a heat spreader due to its high thermal conductivity.
c) HA-derived foam is used as a heat sink or heat dissipation material due to its high heat diffusion capacity (high thermal conductivity) and high heat dissipation capacity (many surface pores that induce massive air convection microchannels or nanochannels). be able to.
d) Light weight (low density adjustable between 0.001 to 1.8 g / cm ³ ), high thermal conductivity per unit specific weight or unit physical density, and high structural integrity (HA sheet assimilated together) (To form a long electron conduction path) makes this HA-derived foam an ideal material for durable heat exchangers.

Foam-based heat management or heat dissipation devices for HA-derived foam include heat exchangers, heat sinks (eg, heat sinks with fins), heat pipes, high conductive inserts, and thin or thick conduction (between the heat sink and the heat source). Includes sex plates, thermal interface media (or thermal interface materials, TIM), thermoelectric or Pelche cooling plates, and the like.

A heat exchanger is a device used to transfer heat between one or more fluids, eg, a gas and a liquid that flow separately in different channels. The fluid is typically separated by a solid wall to prevent mixing. The HA-derived foam material of the present invention is an ideal material for such walls if the foam is not a fully open cell foam that allows fluid mixing. The method of the present invention allows the production of both open cell and closed cell foam structures. The high surface area of the pores allows for dramatically faster exchange of heat between two or more fluids.

Heat exchangers are widely used in refrigeration systems, air conditioners, heaters, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment. Known examples of heat exchangers are found in internal combustion engines where circulating engine coolant flows through the coil while the air flows too far through the radiator coil, which cools the coolant and heats the inflow air. Solid walls (eg, making up a radiator coil) are usually made from high thermal conductivity materials such as Cu and Al. The HA-derived foams of the present invention, which have either higher thermal conductivity or higher specific surface area, are excellent alternatives to, for example, Cu and Al.

There are many types of heat exchangers on the market: tube heat exchangers, plate heat exchangers, plate & shell heat exchangers, adiabatic wheel heat exchangers, plate fin heat exchangers, pillow plate heat exchangers, fluid heat. Exchangers, waste heat recovery equipment, dynamic scraping surface heat exchangers, phase change heat exchangers, direct contact heat exchangers, and microchannel heat exchangers. All of these types of heat exchangers can take advantage of the exceptionally high thermal conductivity and specific surface area of the foam materials of the present invention.

Further, the solid HA-derived foam of the present invention can be used in a heat sink. Heat sinks are widely used in electronic devices for heat dissipation purposes. Central processing units (CPUs) and batteries of portable microelectronic devices (such as notebook computers, tablets, and smartphones) are known heat sources. Typically, a metal or graphite object (eg Cu foil or graphite foil) is brought into contact with a hot surface, which conducts heat (mainly by conduction and convection and, to a lesser extent, by radiation) to the outer surface or outside air. Helps to spread to. Often, a thin thermal interface material (TIM) intervenes between the hot surface of the heat source and the heat spreader or thermal diffusion surface of the heat sink. (Also, the HA-derived foam of the present invention can be used as TIM).

Heat sinks typically have one or more flat surfaces that ensure good thermal contact with the components to be cooled, and numerous combs or fins that increase surface contact with air and thus increase heat dissipation rates. It consists of a highly conductive material structure having. A heatsink may be used with a fan to increase the speed of airflow over the heatsink. The heat sink can have multiple fins (enlarged or protruding surface) to improve heat transfer. In electronic devices where the amount of space is limited, the shape / arrangement of the fins must be optimized for maximum heat transfer density. Alternatively or further, cavities (reverse fins) may be embedded in the area formed between adjacent fins. These cavities are effective in extracting heat from various heat generators to the heat sink.

Typically, an integrated heat sink is a heat collector (core or substrate) and at least one heat dissipation member (eg, fins or fins) essential to the heat collector (base) to form a finned heat sink. And include. The fins and core are naturally connected or integrated together to form a unity without the use of externally applied adhesives or mechanical fixing means to connect the fins to the core. The heat collecting substrate has a surface that is in thermal contact with a heat source (eg, an LED), collects heat from this heat source, and dissipates heat into the air through the fins.

As an exemplary embodiment, FIG. 10 provides schematics of two heat sinks: 300 and 302. The first heat sink includes a heat collecting member (or base material member) 304 and a plurality of fins or heat radiating members (for example, fin 306) connected to the base material member 304. The substrate member 304 is shown to have a heat collecting surface 314 that is intended to be in thermal contact with the heat source. The heat dissipation member or fin 306 is shown to have at least a heat dissipation surface 320.

Particularly useful embodiments are (a) a substrate 308 comprising a heat sink surface 318 and (b) a plurality of isolated parallel planar fin members supported by or integrated with the substrate 308. For example, an integrated radial heatsink 302 comprising a heatsink assembly with radial fins comprising 310, 312) as two embodiments, wherein a planar fin member (eg, 310) comprises at least one heat dissipation surface 322. Multiple parallel planar fin members are preferably equally spaced apart.

The HA-derived foams of the present invention are highly elastic and resilient, and are themselves good thermal interface materials as well as very effective thermal diffusion elements. In addition, this highly conductive foam can also be used as an insert for electronic cooling and to facilitate heat removal from small chips to the heat sink. Since the space occupied by the highly conductive material is of primary concern, it is a more efficient design that utilizes the highly conductive pathways that can be embedded in the heat generator. The elastic and highly conductive solid graphene foams disclosed herein fully meet these requirements.

Due to its high elasticity and high thermal conductivity, the solid HA-derived foams of the present invention are placed as a heat transfer interface between the heat source and the cold flow fluid (or any other heat sink) to improve cooling performance. It is made into a thick plate. In such an arrangement, the heat source is cooled under a plate of thick HA-derived foam instead of being cooled in direct contact with the coolant. Thick plates of HA-derived foam can significantly improve heat transfer between the heat source and the coolant by conducting the heat flow in an optimal manner. No additional pumping force or special heat transfer area is required.

HA-derived foam is also an outstanding material for making heat pipes. A heat pipe is a heat transfer device that uses the evaporation and condensation of a two-phase working fluid or coolant that transports large amounts of heat using very small differences in temperature between hot and cold interfaces. Conventional heat pipes consist of a sealed hollow tube made of a thermally conductive metal such as Cu or Al and a wick that returns the working fluid from the evaporator to the cooler. The pipe contains both saturated fluid and vapor of working fluid (such as water, methanol or ammonia) and all other gases are removed. However, both Cu and Al are susceptible to oxidation or corrosion and therefore their performance deteriorates relatively quickly over time. In contrast, HA-derived foams are chemically inert and do not have these oxidation or corrosion problems. Heat pipes for electronic heat management can have a foam envelope and a wick and use water as the working fluid. If the heat pipe needs to operate below the freezing point of water, HA-derived foam / methanol may be used, and HA-derived foam / ammonia heat pipes may be used for electronics cooling in space.

The Pelche cooling plate operates on the basis of the Pelche effect, which creates a heat flux between the junctions of two different conductors of electricity by applying an electric current. This effect is commonly used to cool electronic components and small devices. In practice, many such joints may be arranged in series to increase the effect on the amount of heating or cooling required. HA-derived foam may be used to improve thermal efficiency.

Filtration and Fluid Absorption Applications HA-derived foams can be made to contain microscopic pores (<2 nm) or mesoscale pores with pore diameters of 2 nm to 50 nm. In addition, the HA-derived foam can be made to contain micron-scale pores (1 to 500 μm). Based solely on well-controlled pore size, the HA-derived foam can be an extraordinary filter material for air or water filtration.

In addition, different amounts and / or types of humic acid (HA) pore walls are controlled by controlling the chemistry of the humic acid (HA) pore wall (eg, as reflected by the percentage of O, F, N, H, etc. in the foam). Functional groups can be donated to the pore walls. In other words, simultaneous or single control of both pore size and chemical functional groups at different sites of internal structure is considered to be usually mutually exclusive, as well as many unexpected properties, synergistic effects. It offers unprecedented flexibility or the highest degree of freedom in designing and manufacturing HA-derived foams that exhibit a unique combination of properties (eg, some parts of the structure are hydrophobic and others). It is hydrophilic or the foam structure is both hydrophobic and lipophilic). A surface or material is said to be hydrophobic when water is repelled from this material or surface and the hydrophobic surface or water droplets placed on the material form 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 invention also provides an oil removal, oil separation, or oil recovery device that contains the HA-derived foam of the invention as an oil absorbing or oil separating element. Also provided are solvent removal or solvent separation devices containing HA-derived foam as a solvent absorbing element.

The main advantage of using the HA-derived foam as an oil absorbing element is its structural integrity. Due to the chemical assimilation of the HA sheet and thus the high structural integrity, the resulting foam does not crumble over repeated oil absorption operations. In contrast, we have found that graphene film oil-absorbing elements made by hot water reduction, vacuum auxiliary filtration, or lyophilization collapse after absorbing oil two or three times. There is nothing to hold together these otherwise separated graphene sheets (other than the weak van der Waals forces that exist before the first contact with the oil). When these graphene sheets are wetted with oil, they can no longer return to their original shape of the oil absorbing element.

Another major advantage of the technology is in designing and manufacturing oil absorbing elements that can absorb oil up to 400 times their own weight while still maintaining their structural shape (without significant expansion). Flexibility. This amount depends on the specific volume of the pores of the foam, which can be controlled primarily by the ratio of the amount of the original carrier polymer particles to the amount of HA molecules or sheets before heat treatment.

The invention also provides a method of separating / recovering oil from an oil-water mixture (eg, spilled water or waste water from oil sands). The methods include (a) providing an oil absorbing element containing an integral HA-derived foam, (b) contacting the oil-water mixture with an element that absorbs oil from the mixture, and (c) mixing the oil absorbing element. Includes a step of removing from the element and extracting the oil from the element. Preferably, the method comprises (d) an additional step of reusing the element.

Furthermore, the present invention provides a method of separating an organic solvent from a solvent-water mixture or from a multi-solvent mixture. The method comprises (a) providing an organic solvent absorbing element containing an integrated HA-derived foam, and (b) the element being an organic solvent-water mixture or a plurality of solvents containing a first solvent and at least a second solvent. The step of contacting with the mixture, (c) allowing this element to absorb the organic solvent from the mixture, or the step of allowing the first solvent to be absorbed from at least the second solvent, and (d) mixing the elements. Includes a step of removing from the element and extracting an organic solvent or a first solvent from the element. Preferably, the method comprises an additional step (e) of reusing the solvent absorbing element.

The following examples are used to illustrate some specific details about the best practices of the invention and should not be construed as limiting the scope of the invention.

Example 1: humic acid from leonaldite and reduced humic acid humic acid can be extracted from leonaldite in very high yield (range 75%) by dispersing leonaldite in a basic aqueous solution (pH 10). Subsequent acidification of the solution gives a precipitate of humic acid powder. In the experiment, 3 g of leonaldite was dissolved under 300 ml of double deionized water containing a 1 M KOH (or NH ₄ OH) solution under magnetic agitation. The pH value was adjusted to 10. The solution was then filtered to remove any large particles or any residual impurities. The resulting humic acid dispersion containing HC alone or in the presence of a foaming agent was cast on a glass substrate to form a series of films for subsequent heat treatment.

In some samples, a chemical foaming agent (hydrazodicarbonamide) was added to the suspension immediately prior to casting. Next, a doctor blade was used to cast the resulting suspension onto the glass surface and apply shear stress to induce HA molecular orientation. The resulting HA coated film has a thickness that can vary from about 10 nm to 500 μm (preferably and typically 1 μm to 50 μm) after removal of the liquid.

To produce HA foam test pieces, the HA coating film is then heat treated for 1-8 hours, typically requiring an initial heat reduction temperature of 80-350 ° C., followed by 0.5-5. It is subjected to heat treatment at a second temperature of 1,500 to 2,850 ° C. for hours. It may be pointed out that it has been found essential to apply compressive stress to the coated film sample during the first heat treatment. This compressive stress appears to have helped maintain good contact between HA molecules or sheets due to chemical assimilation and ligation between HA molecules or sheets during the formation of pores. Without such compressive stresses, the heat-treated films are typically over-porosity, and the constituent hexagonal carbon atomic planes within the pore walls are very imperfectly oriented / aligned and chemically chemical to each other. Cannot be assimilated and linked. As a result, the thermal conductivity, electrical conductivity, and mechanical strength of graphene foam are severely compromised.

Example 2: Various Foaming Agents and Pore Formation (Bubble Production) Methods In the field of plastic processing, chemical foaming agents are mixed in plastic pellets in the form of powders or pellets and dissolved at higher temperatures. Above certain temperatures specified for the dissolution of the foaming agent, a gas reaction product (usually nitrogen or CO ₂ ) is produced, which acts as a foaming agent. However, the chemical foaming agent cannot be dissolved in the graphene material, which is a solid rather than a liquid. This poses the challenge of utilizing chemical foaming agents to create pores or cells in the graphene material.

After extensive experimentation, graphene pores or bubbles using almost any chemical foaming agent (eg in powder or pellet form) when the first heat treatment temperature is sufficient to activate the blowing reaction. We have found that it can be made in a dry layer of. The chemical foaming agent (powder or pellet) can be dispersed in a liquid medium to become a second component in the suspension, which can be deposited on a solid supporting substrate to form a wet layer. This wet layer of HA material may then be dried and heat treated to activate the chemical foaming agent. After the chemical foaming agent is activated to generate bubbles, the resulting foamed HA structure is generally maintained even when higher heat treatment temperatures are subsequently applied to the structure. This is really totally unexpected.

The chemical foaming agent (CFA) can be an organic or inorganic compound that releases a gas when thermally decomposed. CFA is typically used to obtain medium to high density foams and is often used with physical foaming agents to obtain low density foams. CFA can be categorized as either endothermic or exothermic, which means the type of degradation they undergo. The endothermic type absorbs energy when decomposed, typically releasing carbon dioxide and moisture, while the exothermic type releases energy when decomposed, usually producing nitrogen. The total gas generation and gas pressure released by the exothermic foaming agent is often higher than the total gas generation and gas pressure of the endothermic type. Endothermic CFA is generally known to decompose in the range 130-230 ° C (266-446 ° F), while some of the more common exothermic foaming agents are at about 200 ° C (392). Decompose at ° F). However, the extent of decomposition of most exothermic CFA can be reduced by the addition of certain compounds. The CFA activation (decomposition) temperature is in the range of our heat treatment temperature. Examples of suitable chemical foaming agents include sodium bicarbonate (baking soda), hydrazine, hydrazide, azodicarbonamide (exothermic chemical foaming agent), nitroso compounds (eg N, N-dinitrosopentamethylenetetramine), hydrazine derivatives (eg, N, N-dinitrosopentamethylenetetramine). For example, 4,4'-oxybis (benzenesulfonylhydrazide) and hydrazodicarbonamide), and hydrogen carbonate (eg, sodium hydrogencarbonate) are included. All of these are commercially available in the plastics industry.

In the production of foamed plastics, a physical foaming agent is weighed into the plastic melt during foam extrusion or injection molding foaming, or supplied to one of the precursor materials during the foaming of polyurethane. It has not been previously known that physical foaming agents can be used to create pores in HA materials that are in a solid state (not melted). Surprisingly, we have observed that a physical foaming agent (eg, CO ₂ or N ₂ ) can be injected into a stream of HA suspension prior to being coated or cast onto a supporting substrate. This results in a foam structure even when the liquid medium (eg water and / or alcohol) is removed. The dried layer of graphene material can maintain a controlled amount of pores or bubbles during liquid removal and subsequent heat treatment.

Technically viable foaming agents include carbon dioxide (CO ₂ ), nitrogen (N ₂ ), isobutane (C ₄ H ₁₀ ), cyclopentane (C ₅ H ₁₀ ), isopentane (C ₅ H ₁₂ ), CFC. -11 (CFCI ₃ ), HCFC-22 (CHF ₂ CI), HCFC-142b (CF ₂ CICH ₃ ), and HCFC-134a (CH ₂ FCF ₃ ) are included. However, environmental safety is a major factor to consider when choosing a foaming agent. Its impact on the Montreal Protocol and the resulting agreement poses significant challenges for foam manufacturers. Despite the effective properties and simple handling of chlorofluorocarbons previously applied, there was a global agreement banning them due to their ozone depletion potential (ODP). Partially halogenated chlorofluorocarbons are also not environmentally safe and are therefore already banned in many countries. Another option is hydrocarbons such as isobutane and pentane, as well as gases such as CO ₂ and nitrogen.

Except for those regulated substances, all foaming agents listed above were tested in our experiments. For both physical and chemical foaming agents, the amount of foaming agent introduced into the suspension is defined as the weight ratio of foaming agent to HA material, which is typically 0 / 1.0-1. It is 0.0 / 1.0.

Example 3: Preparation of humic acid from coal In a typical procedure, 300 mg of coal was suspended in concentrated sulfuric acid (60 ml) and nitric acid (20 ml), followed by cup sonication for 2 hours. The reaction was then stirred and heated in an oil bath at 100 ° C. or 120 ° C. for 24 hours. The solution was cooled to room temperature, poured into a beaker carrying 100 ml of ice, followed by the addition of NaOH (3M) until the pH value reached 7.

In one experiment, the neutralizing mixture was then filtered through a 0.45 mm polytetrafluoroethylene membrane and the filtrate was dialyzed in a 1,000 Da dialysis bag for 5 days. Due to the larger humic acid sheet, cross-flow extrafiltration can be used to reduce the time to 1-2 hours. After purification, the solution was concentrated using rotary evaporation to give a solid humic acid sheet. Only these humic acid sheets and their mixtures with foaming agents were redispersed in solvents (ethylene glycol and alcohol, separately) to give several dispersion samples for subsequent casting or coating. ..

Suspension containing various amounts (1% to 30% by weight) of chemical foaming agent (N, N-dinitrosopentamethylenetetramine or 4,4'-oxybis (benzenesulfonyl hydrazide)) in the HA sheet. It was added to the turbid liquid. Then, the suspension was cast on the glass surface using a doctor blade and shear stress was applied to induce the orientation and proper placement of the HA molecule or sheet. Immediately before casting. Several samples were cast, including samples made using CO ₂ as the physical foaming agent introduced into the suspension. After removing the liquid, the resulting HA film was about It has a thickness that can vary from 1 to 100 μm.

The HA film was then subjected to a heat treatment requiring an initial (first) heat reduction temperature of 80-1,500 ° C. for 1-5 hours. This first heat treatment generated the domain of the hexagonal carbon atom plane in the foam or pore walls of HA foam (when HTT is <300 ° C.) and large sheet HA molecules (HTT 300-1, 1. When it is 500 ° C.). Next, some of the foam samples can be exposed to a second temperature of 1,500-2,850 ° C. to further improve the graphene-like domain of the hexagonal carbon atom plane in the foam wall (more graphitized). It was examined whether it was ordered or had a higher degree of crystallinity).

Comparative Example 3-a: CVD graphene foam procedure on Ni foam template is described in Publication: Chen, Z. et al. et al. , "Three-dimensional flexible and concave intensive integrated graphene networks green by chemical vapor deposition," Nat. Mater. 10, 424-428 (2011) was diverted from the procedure disclosed. Nickel foam, a porous structure with nickel interconnected 3D scaffolds was selected as the template for the growth of graphene foam. Briefly, carbon was introduced into the nickel foam by decomposing CH ₄ at 1,000 ° C. under ambient pressure, and then a graphene film was deposited on the surface of the nickel foam. Wrinkles and wrinkles were formed on the graphene film due to the difference in thermal expansion rates between nickel and graphene. In order to recover (separate) the graphene foam, the Ni frame must be removed by etching. Before removing the nickel skeleton by etching with a hot HCl (or FeCl ₃ ) solution, a thin layer of poly (methylmethacrylate) (PMMA) is deposited on the surface of the graphene film as a support and a graphene network during nickel etching. The structure was prevented from being crushed. After careful removal of the PMMA layer with hot acetone, a brittle graphene foam sample was obtained. The use of the PMMA support layer is important for making self-supporting films of graphene foam. Only severely distorted and deformed graphene foam samples were obtained without the PMMA support layer. This is a time-consuming, non-environmentally friendly and non-scalable method.

Comparative Example 3-b: Conventional Graphite Foam from Pitch-based Carbon Foam Pitch powder, granules, or pellets are placed in an aluminum mold having the desired final shape of the foam. The Mitsubishi ARA-24 mesophase pitch was used. The sample was degassed to less than 1 torr and then heated to a temperature of about 300 ° C. At this point, the vacuum was released into the nitrogen blanket and then a pressure of up to 1,000 psi was applied. Next, the temperature of the system was raised to 800 ° C. This was done at a rate of 2 ° C./min. The temperature was maintained for at least 15 minutes to achieve immersion, then the furnace was turned off and cooled to room temperature at a rate of about 1.5 ° C./min while releasing pressure at a rate of about 2 psi / min. The final foam temperatures were 630 ° C and 800 ° C. During the cooling cycle, the pressure was gradually released to atmospheric conditions. The foam was then heat treated to 1050 ° C. under a nitrogen blanket and then heat treated to 2500 ° C. and 2800 ° C. in a graphite crucible in argon with separate feeds.

The sample from the foam was machined into a sample for measuring thermal conductivity. The bulk thermal conductivity was in the range of 67 W / mK to 151 W / mK. The sample density was 0.31 to 0.61 g / cm ³ . When weight is taken into account, the specific thermal conductivity of the pitch-derived foam is about 67 / 0.31 = 216 and 151 / 0.61 = 247.5 W / mK / specific gravity (or / physical density). ..

The compressive strength of the sample having an average density of 0.51 g / cm ³ was 3.6 MPa as measured, and the compressive modulus was 74 MPa as measured. In contrast, the HA-derived graphite foams of the present invention with comparable physical densities have compressive strength and compressive modulus of 5.7 MPa and 103 MPa, respectively.

Shown in FIG. 3 (A) is the value-to-weight ratio of thermal conductivity of HA-derived foam, mesophase pitch-derived graphite foam, and Ni foam template-assisted CVD graphene foam. These data clearly demonstrate the following unexpected results:
1) HA-derived foams produced by the method of the present invention have significantly higher thermal conductivity when compared to both mesophase pitch-derived graphite foams and Ni foam template-assisted CVD graphene, given the same physical density. Is shown.
2) CVD graphene is derived from HA which is never oxidized and is very defective (high defect group and therefore low conductivity) after oxygen-containing functional groups have been removed by conventional thermal or chemical reduction methods. This is quite surprising given the view that it is essentially pure graphene with higher thermal conductivity compared to the hexagonal carbon atomic plane. These very high thermal conductivity values observed using the HA-derived graphite foam produced here are very surprising to us.
3) Given the same amount of solid material, the HA-derived foam of the present invention after heat treatment at HTT> 1,500 ° C. shows that it is essentially the most conductive and completes high level graphite crystals. Reflects (larger crystal size, less grain boundaries and other defects, better crystal orientation, etc.). This is also unexpected.
4) The values of the specific conductivity of the HA-derived foam and the fluorinated HA-derived foam of the present invention (FIG. 5) show a value of 250 to 490 W / mK per unit specific weight, but the specific conductivity of the other two foam materials. The value of is typically lower than 250 W / mK per unit weight.

Comparative Example 3-c: Preparation of Pure Graphene Foam (0% Oxygen) Pure, recognizing the possibility of high defects in the HA sheet acting to reduce the conductivity of individual graphene surfaces. We decided to investigate whether the use of graphene sheets (non-oxidized and oxygen-free, non-halogenated and halogen-free, etc.) could result in graphene foam with higher thermal conductivity. Pure graphene sheets were manufactured using direct sonication methods (also known in the art as liquid phase desquamation).

In a typical procedure, 5 grams of graphite flakes finely ground to a size of about 20 μm or less contain 1,000 mL of deionized water (Zonyl® FSO from DuPont, 0.1% by weight of dispersion aid). ) To obtain a suspension. An ultrasonic energy level of 85 W (Branson S450 Ultrasonicator) was used for peeling, separating and grinding graphene sheets for 15 minutes to 2 hours. The obtained graphene sheet is pure graphene that is not oxidized at all, contains no oxygen, and is relatively free of defects. There are no other non-carbon elements.

Surfactant various amounts (1% to 30% by weight relative to graphene material) of chemical foaming agent (N, N-dinitrosopentamethylenetetramine or 4,4'-oxybis (benzenesulfonyl hydrazide) with pure graphene sheet Added to the suspension containing the activator. Next, the suspension was cast onto the glass surface. CO ₂ was used as the physical foaming agent to be introduced into the suspension immediately prior to casting. Several samples were cast, including those produced in. The resulting graphene film has a thickness that can vary from about 10 to 100 μm after removal of the liquid. It was subjected to a heat treatment at a temperature of 80-1,500 ° C. for 1-5 hours, which produced graphene foam.

Shown are thermal conductivity data for a series of HA-derived foams and a series of pure graphene-derived foams, both plotted for the same final (highest) heat treatment temperature. These data show that the thermal conductivity of HA-derived foam is very sensitive to the final heat treatment temperature (HTT). Even when the HTT is very low, apparently some types of HA molecule binding and assimilation or crystallization completion reactions are already activated. Thermal conductivity increases monotonically with the final HTT. In contrast, the thermal conductivity of pure graphene foam remains relatively constant until a final HTT of about 2,500 ° C is reached, signaling the start and completion of recrystallization of graphite crystals. There are no functional groups in pure graphene, such as -COOH and -OH in HA, that allow chemical ligation of molecules with relatively low HTT. Using HTT at only 1,250 ° C, the HA molecule and the resulting hexagonal carbon atomic plane are assimilated, resulting in significantly larger graphene-like hexagonal carbon with reduced grain boundaries and less interruption of electron transport paths. It is possible to form a sheet. Although HA-derived sheets are inherently more defective than pure graphene, the methods of the invention allow HA molecules to form graphite foam that is superior to pure graphene foam. This is another unexpected result.

Comparative Example 3-d: Preparation of Graphene Oxide (GO) Suspension from Natural Graphene and Graphene Foam from Hydrothermally Reduced Graphene Oxide Graphene Oxide contains graphite flakes in a ratio of 4: 1: 0.05 nitric acid. It was prepared by oxidizing at 30 ° C. with an oxidizing agent liquid consisting of sodium nitrate and potassium permanganate. When the natural graphite flakes (14 μm particle size) are immersed and dispersed in the oxidant mixture liquid for 48 hours, the suspension or slurry appears optically opaque and dark and remains intact. After 48 hours, the reaction mass was washed 3 times with water to adjust the pH value to at least 3.0. The final amount of water was then added to prepare a series of GO-aqueous suspensions. We have observed that the GO sheet forms a liquid crystal phase when the GO sheet occupies a weight fraction of> 3% and typically 5% -15%.

Self-assembled graphene hydrogel (SGH) samples were then prepared by the hydrothermal method. In a typical procedure, SGH can be readily prepared by heating a 2 mg / mL homogeneous graphene oxide (GO) aqueous dispersion sealed in a 180 ° C. Teflon-lined autoclave over 12 hours. .. SGH containing about 2.6% (by weight) graphene sheet and 97.4% water has an electrical conductivity of about 5 × 10 ^-3 S / cm. When dried and heat treated at 1,500 ° C., the resulting graphene foam exhibited an electrical conductivity of about 1.5 × 10 ^-1 S / cm, which was produced by heat treatment at the same temperature of the present invention. It is less than 1/2 of the electrical conductivity of HA-derived foam.

Comparative Example 3-e: Plastic bead template assisted formation of reduced graphene oxide foam Rigid template for macroporous bubble-generating graphene film (MGF) The indicated ordered assembly was made. Unidisperse polymethylmethacrylate (PMMA) latex spheres were used as the rigid template. The GO liquid crystal produced in Comparative Example 3-d was mixed with the PMMA sphere suspension. Subsequent vacuum filtration is then performed to create an assembly of PMMA spheres and GO sheet, which is wrapped around the PMMA bead. The composite film was stripped from the filter, air dried and baked at 800 ° C. to remove the PMMA template, while at the same time heat reducing GO to RGO. The gray self-supporting PMMA / GO film turned black after calcination, but the graphene film remained porous.

FIG. 3B shows the thermal conductivity values of the HA-derived foam of the present invention, the GO foam produced by the sacrificial plastic bead template support method, and the hydrothermally reduced GO graphene foam. Most surprisingly, given the same HTT, the HA-derived foams of the present invention show the highest thermal conductivity. Also, the electrical conductivity data summarized in FIG. 4 is consistent with this conclusion. Given the same amount of solid material, the deposition of the HA suspension of the present invention (with stress-induced orientation) and subsequent heat treatment is essentially the most conductive and the highest level of graphite crystal completion (with stress-induced orientation). These data further support the view that along the pore walls, HA-derived foams that reflect larger crystal dimensions, fewer grain boundaries and other defects, better crystal orientation, etc.) are produced.

All prior art methods for producing graphite foam or graphene foam have a physical density in the range of only about 0.2-0.6 g / cm ³ for most of the intended use and a pore size. It should be pointed out that is typically likely to provide a very large (eg 20-300 μm) macroporous foam. In contrast, the present invention provides a method of producing HA-derived foams with densities that can be as low as 0.01 g / cm ³ and as high as 1.7 g / cm ³ . The pore size can vary from medium scale (2-50 nm) to macroscopic scale (1-5 μm) depending on the content of non-carbon elements and the amount / type of foaming agent used. This level of flexibility and versatility in designing various types of graphite foam is unprecedented and unmatched by any of the prior art methods.

Example 4: Preparation of Fluorinated HA Foam In a typical procedure, a sheet of HA-derived foam was fluorinated in an autoclave reactor with the vapor of chlorine trifluoride to give a fluorinated HA-carbon hybrid film. .. Fluorination times at different times were considered to achieve different degrees of fluorination. Next, a sheet of fluorinated HA-derived foam was separately immersed in a container containing each of the chloroform-water mixture. These foam sheets selectively absorb chloroform from water, and as shown in FIG. 9, the amount of absorbed chloroform increases with the degree of fluorination until the fluorine content reaches 7.2% by weight. We observe.

Example 5: Preparation of Nitrogenized HA Foam Several HA-derived foams prepared in Example 3 are immersed in a 30% H ₂ O ₂ aqueous solution for 2 to 48 hours to control 2 to 25% by weight. Oxidized HA-derived foam with oxygen content was obtained.

Several oxidized HA-derived foam samples were mixed with different proportions of urea, and the mixture was heated in a microwave reactor (900 W) for 0.5-5 minutes. The product was washed several times with deionized water and vacuum dried. The product obtained was nitrogenized HA foam. Nitrogen content was 3% to 17.5% by weight as measured by elemental analysis.

It may be pointed out that the different functionalization treatments of HA-derived foams are for different purposes. For example, oxidized HA foam structures are particularly effective as oil absorbers from oil-water mixtures (ie, oil spills into water and then mixed together), FIGS. 7 and 8. In this case, the monolithic HA-derived foam structure (having 0-15 wt% oxygen) is both hydrophobic and lipophilic (FIG. 7). A surface or material is said to be hydrophobic when water is repelled from this material or surface and water droplets placed on the hydrophobic surface or material form a large contact angle. A surface or material is said to be lipophilic if it has a strong affinity for oil rather than water.

Also, different contents of O, F, and / or N are such that the HA-derived foams of the invention absorb different organic solvents from water or separate one organic solvent from a mixture of multiple solvents. Enables.

Example 6: characterization of various HA-derived foams and conventional graphite foams The internal structure (crystal structure and orientation) of several series of HA-carbon foam materials was investigated using X-ray diffraction. The X-ray diffraction curve of natural graphite typically shows a peak of about 2θ = 26 °, which corresponds to the spacing (d ₀₀₂ ) between graphenes at about 0.3345 nm. The RHA walls of the hybrid foam material typically show d ₀₀₂ spacing from 0.3345 nm to 0.40 nm, but more typically up to 0.34 nm.

The heat treatment temperature of 2,750 ° C. for the foam structure under compression over 1 hour reduces the _d002 spacing to about _0.3354 nm, which is equal to the d002 spacing of the graphite single crystal. Further, the second diffraction peak having high intensity appears at 2θ = 55 °, which corresponds to the X-ray diffraction from the (004) plane. The (004) peak intensity, or I (004) / I (002) ratio to the (002) intensity on the same diffraction curve is a good indication of the crystal perfection of the graphene-like surface and the preferred orientation. For all graphite materials heat treated at temperatures below 2,800 ° C., the (004) peak is either absent or relatively weak, with an I (004) / I (002) ratio <0. It is 1. The I (004) / I (002) ratio of graphite material heat-treated at 3,000 to 3,250 ° C. (eg, highly oriented pyrolytic graphite, HOPG) is in the range of 0.2 to 0.5. In contrast, graphene foam prepared in the final HTT at 2,750 ° C. over 1 hour showed an I (004) / I (002) ratio of 0.78 and a mosaic spread value of 0.21 and a pore wall. Indicates that it is a nearly perfect graphite single crystal with a good degree of favorable orientation (when prepared under compressive force).

The "mosaic spread" value is obtained from the full width at half maximum of the (002) reflection of the X-ray diffraction intensity curve. This indicator for degree of order characterizes the graphite or graphene crystal size (or grain size), the amount of grain boundaries and other defects, and the preferred grain orientation. A nearly perfect single crystal of graphite is characterized by having a mosaic spread value of 0.3-0.6. Some of our HA-derived foams have a mosaic spread value in this range of 0.2-0.4 when manufactured using a final heat treatment temperature of 2,500 ° C or higher.

A heat treatment temperature of only 500 ° C. is sufficient to keep the average interplanetary spacing between hexagonal carbon atom planes along the pore walls below 0.4 nm, the average interplanetary spacing of natural graphite or the average surface of graphite single crystals. It should be pointed out that we are getting closer and closer to the interval. The advantage of this method is that by this HA liquid crystal suspension coating and heat treatment method, planar HA molecules are organized, oriented / aligned, and chemically assimilated so that all graphene-like hexagonal carbon atomic planes are now laterally dimensioned. It means that a larger unified structure (significantly larger than the length and width of the original HA molecule) could be formed in. Possible chemical linkage and assimilation mechanisms are illustrated in FIG. This resulted in extraordinary thermal and electrical conductivity values.

In conclusion, we have successfully developed absolutely new, novel, unexpected and distinctly different classes of HA foam or HA-derived graphite foam materials and related manufacturing methods. Chemical composition (% of oxygen, fluorine, and other non-carbon elements), structure (crystal completion, crystal grain size, defect group, etc.), crystal orientation, morphology, manufacturing process, and properties of this new class of foam material It is fundamentally different and distinct from graphite foam derived from mesophase pitch, foam derived from CVD graphene, and graphene foam from hydrothermal reduction of GO, as well as sacrificial bead template-assisted RGO foam. The thermal conductivity, electrical conductivity, elastic modulus, and flexural strength exhibited by the foam materials of the present invention are much higher than those of the prior art foam materials.

Claims (35)

In a method for producing carbon / graphite foam derived from humic acid,
(A) In the step of preparing a humic acid dispersion in which a plurality of humic acid molecules or sheets are dispersed in a liquid medium, the humic acid is humic acid oxide, reduced humic acid, fluorinated humic acid, or chlorinated humic acid. , Brominated humic acid, iodide humic acid, hydride humic acid, nitrogenized humic acid, doped humic acid, chemically functionalized humic acid, and combinations thereof. A step of containing an optional foaming agent having a humic acid to humic acid weight ratio of 0 / 1.0 to 1.0 / 1.0, and a step of containing the foaming agent.
(B) A step of distributing and depositing the humic acid dispersion on the surface of the supporting substrate to form a wet layer of humic acid.
(C) A step of partially or completely removing the liquid medium from the wet layer of humic acid to form a dry layer of humic acid.
(D) 80 ° C. to 3,200 ° C. at a desired heating rate sufficient to induce volatile gas molecules from the non-carbon element in the dried layer of humic acid or to activate the effervescent agent. In the step of producing the carbon / graphite foam derived from humic acid, which is composed of a plurality of pores and pore walls by heat treatment at the first heat treatment temperature of humic acid, the pore walls are single layer or several layers of humic acid. It contains an acid-derived hexagonal carbon atomic plane or sheet, and the interplanetary spacing d of 0.3354 nm to 0.60 nm when the multi-layer hexagonal carbon atomic surface or sheet is measured by X-ray diffraction. ₀₀₂ It comprises a step of having 2 to 10 layers of a laminated hexagonal carbon atomic surface having, and the single layer or several layers hexagonal carbon atomic surface containing 0.01% by weight to 25% by weight of non-carbon elements. How to feature. The method of claim 1, wherein the partitioning and deposition procedure comprises subjecting the humic acid dispersion to an orientation-induced stress. In the method according to claim 1, a step of heat-treating the carbon / graphite foam derived from fumic acid at a second heat treatment temperature higher than the first heat treatment temperature for a sufficient time to obtain the carbon / graphite foam is further performed. In the method according to claim 1, wherein the pore wall has a surface spacing d of 0.3354 nm to 0.36 nm. ₀₀₂ A method comprising a laminated hexagonal carbon atomic plane and a content of less than 2% by weight of a non-carbon element. The method according to claim 1, wherein the foaming agent is a physical foaming agent, a chemical foaming agent, a mixture thereof, a dissolving and leaching agent, or a mechanically introduced foaming agent. In the method according to claim 1, which is a roll-to-roll method, the steps (b) and (c) are a step of supplying the supporting base material from the feeder roller to the deposition region and supporting the humic acid dispersion. A step of continuously or discontinuously depositing on the surface of the substrate to form the wet layer of humic acid on it, and drying the wet layer of humic acid to form a dry layer of humic acid. A method comprising: collecting the dried layer of humic acid deposited on the supporting substrate on a collector roller. The method according to claim 1, wherein the first heat treatment temperature is 100 ° C to 1,500 ° C. In the method according to claim 3, the second heat treatment temperature is (A) 300 to 1,500 ° C., (B) 1,500 to 2,100 ° C., and (C) 2,100 to 3,200 ° C. A method comprising at least a temperature selected from the group consisting of. In the method of claim 3, the second heat treatment temperature is in the range of 300 to 1,500 ° C. for at least 1 hour and then in the range of 1,500 to 3,200 ° C. for at least 1 hour. A method characterized by including the temperature of. The method according to claim 3, wherein the non-carbon element contains an element selected from the group consisting of oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, and boron. The method according to claim 3, wherein the step (d) of heat-treating the dried layer of humic acid at the first heat treatment temperature is performed under compressive stress. The method of claim 1, further comprising a compression step of reducing the thickness, pore size, or porosity level of the carbon / graphite foam. In the method of claim 3, the first and / or second heat treatment temperature comprises a temperature in the range of 300 ° C to 1,500 ° C and the carbon / graphite foam has an oxygen content of less than 1% or. It has a non-carbon content and pore walls with interplanar spacing of less than 0.35 nm, a thermal conductivity of at least 250 W / mK per unit specific density, and / or an electrical conductivity of 2,500 S / cm or more per unit specific gravity. A method characterized by that. In the method of claim 3, the first and / or second heat treatment temperature comprises a temperature in the range of 1,500 ° C to 2,100 ° C, and the carbon / graphite foam contains less than 0.01% oxygen. Content or non-carbon content, pore walls with interplanar spacing of less than 0.34 nm, thermal conductivity of at least 300 W / mK per unit specific density, and / or electrical conductivity of 3,000 S / cm or more per unit specific gravity. A method characterized by having. In the method of claim 3, the first and / or second heat treatment temperature comprises a temperature higher than 2,100 ° C. and the carbon / graphite foam contains an oxygen content of 0.001% or less or a non-carbon content. Amount, pore walls with interplanar spacing of less than 0.336 nm, mosaic spread value of 0.7 or less, thermal conductivity of at least 350 W / mK per unit weight, and / or more than 3,500 S / cm per unit weight. A method characterized by having electrical conductivity. In the method of claim 3, the first and / or second heat treatment temperature comprises a temperature of 2,500 ° C. or higher, and the carbon / graphite foam has a laminated hexagon with an interplane spacing of less than 0.336 nm. Pore wall containing graphite surface, mosaic spread value of 0.4 or less, thermal conductivity greater than 400 W / mK per unit specific gravity, and / or electrical conductivity greater than 4,000 S / cm per unit specific gravity. A method characterized by. In the roll-to-roll method for producing a continuous length sheet of carbon / graphite foam derived from humic acid,
(A) In the step of preparing a humic acid dispersion in which humic acid molecules are dispersed in a liquid medium, a step of the dispersion containing a foaming agent and a step of preparing the humic acid dispersion.
(B) In the step of continuously or discontinuously distributing and depositing the humic acid dispersion on the surface of the supporting base material to form a wet layer of humic acid, the supporting base material is supplied from a feeder roller. The process of being a continuous thin film collected on a collector roller,
(C) A step of partially or completely removing the liquid medium from the wet layer of humic acid to form a dried layer of humic acid in a heated region or a plurality of heated regions.
(D) The dried layer of humic acid is heat-treated in one of the heating regions comprising a heating temperature of 80 ° C. to 500 ° C. at a desired heating rate sufficient to activate the effervescent agent. In the step of producing the humic acid-derived carbon / graphite foam composed of the pores and pore walls of the above, the pore walls contain a single layer or several layers of humic acid-derived hexagonal carbon atomic planes or sheets. , Interplane spacing d of 0.3354 nm to 0.60 nm when the multi-layer hexagonal carbon atomic plane or sheet is measured by X-ray diffraction. ₀₀₂ It comprises a step of having 2 to 10 layers of a laminated hexagonal carbon atomic surface having, and the single layer or several layers of the hexagonal carbon atomic surface containing 0.01% by weight to 25% by weight of non-carbon elements. How to feature. In the method according to claim 1, the carbon / graphite foam derived from humic acid is 0.005 to 1.7 g / cm. ³ Density, 50-3,200m ² A method characterized by having a specific surface area of / g, a thermal conductivity of at least 100 W / mK per unit specific gravity, and / or an electrical conductivity of 500 S / cm or more per unit specific gravity. In the method according to claim 3, the carbon / graphite foam derived from humic acid is 0.005 to 1.7 g / cm. ³ Density, 50-3,200m ² A method characterized by having a specific surface area of / g, a thermal conductivity of at least 100 W / mK per unit specific gravity, and / or an electrical conductivity of 500 S / cm or more per unit specific gravity. In the method according to claim 16, the carbon / graphite foam derived from humic acid is 0.005 to 1.7 g / cm. ³ Density, 50-3,200m ² A method characterized by having a specific surface area of / g, a thermal conductivity of at least 100 W / mK per unit specific gravity, and / or an electrical conductivity of 500 S / cm or more per unit specific gravity. In the method according to claim 1, the carbon / graphite foam derived from humic acid is 0.01 to 1.5 g / cm. ³ A method characterized by having a density of 2 nm or an average pore diameter of 2 nm to 50 nm. In the method according to claim 1, the carbon / graphite foam derived from humic acid is 200 to 3,000 m. ² Specific surface area of / g or 0.1-1.2 g / cm ³ A method characterized by having a density of. In the method of claim 1, the humic acid-derived carbon / graphite foam is in the form of a continuous length roll sheet having a thickness of 100 nm to 10 cm and a length of at least 2 meters, and is produced by a roll-to-roll method. A method characterized by that. In the method according to claim 1, the carbon / graphite foam derived from fumic acid has an oxygen content or a non-carbon content of less than 1% by weight, and the pore walls have an interplanar spacing of less than 0.35 nm. A method comprising a laminated hexagonal carbon atomic plane having a thermal conductivity of at least 200 W / mK per unit specific gravity and / or an electric conductivity of 1,000 S / cm or more per unit specific gravity. In the method according to claim 1, the carbon / graphite foam derived from fumic acid has an oxygen content or a non-carbon content of less than 0.01% by weight, and the pore wall has a surface of less than 0.34 nm. A method comprising a laminated hexatonic graphite plane with an interval, a thermal conductivity of at least 300 W / mK per unit specific gravity, and / or an electrical conductivity of 1,500 S / cm or more per unit specific gravity. .. The surface of the method according to claim 1, wherein the carbon / graphite foam derived from fumic acid has an oxygen content or a non-carbon content of 0.01% by weight or less, and the pore wall has a pore wall of less than 0.336 nm. A method comprising a laminated hexagonal carbon atomic plane with intervals, a thermal conductivity of at least 350 W / mK per unit specific gravity, and / or an electrical conductivity of 2,000 S / cm or more per unit specific gravity. In the method of claim 1, the humic acid-derived carbon / graphite foam has a laminated hexagonal carbon atomic plane with an interplanetary spacing of less than 0.336 nm, a thermal conductivity greater than 400 W / mK per unit specific gravity, and / Or a method comprising a pore wall containing an electrical conductivity greater than 3,000 S / cm per unit specific gravity. The method of claim 1, wherein the pore wall comprises a laminated hexagonal carbon atomic plane with an interplanetary spacing of less than 0.337 nm and a mosaic spread value of less than 1.0. The method according to claim 1, wherein the pore wall contains a three-dimensional network structure of interconnected hexagonal carbon atom planes. The method according to claim 1, wherein the carbon / graphite foam derived from humic acid contains mesoscale pores having a pore diameter of 2 nm to 50 nm. A method for producing an oil removing or oil separating device, which comprises a humic acid-derived carbon / graphite foam produced by the method according to claim 1 as an oil absorbing element. A method for producing a solvent removing or solvent separating device, which comprises a carbon / graphite foam derived from humic acid produced by the method according to claim 1 as a solvent absorbing or solvent separating element. In the method of separating oil from water
a. A step of providing an oil absorbing element containing a carbon / graphite foam derived from humic acid produced by the method according to claim 1.
b. The step of bringing the oil-water mixture into contact with the element that absorbs the oil from the mixture.
c. A step of removing the element from the mixture and extracting the oil from the element.
d. A method comprising a step of reusing the element. In the method of separating an organic solvent from a solvent-water mixture or from a multi-solvent mixture.
a. A step of providing an organic solvent absorbing or solvent separating element containing a carbon / graphite foam derived from humic acid produced by the method according to claim 1.
b. A step of contacting the element with an organic solvent-water mixture or with a plurality of solvent mixtures containing a first solvent and at least a second solvent.
c. A step of allowing the element to absorb the organic solvent from the mixture or separating the first solvent from at least the second solvent.
d. A step of removing the element from the mixture and extracting the organic solvent or the first solvent from the element.
e. A method comprising a step of reusing the element. A method for manufacturing a heat management device, which comprises a carbon / graphite foam derived from humic acid produced by the method according to claim 1 as a heat diffusion or heat dissipation element. The heat management device comprises a heat exchanger, a heat sink, a heat pipe, a highly conductive insert, a conductive plate between the heat sink and a heat source, a heat diffusion component, a heat dissipation component, a heat interface medium, and a thermoelectric or Pelche cooling device. 34. The method of manufacturing a thermal management device according to claim 34, comprising a device selected from the group.

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