WO2018026545A1 - Mousse hybride intégrale d'acide humique-carbone 3d et dispositifs la contenant - Google Patents

Mousse hybride intégrale d'acide humique-carbone 3d et dispositifs la contenant Download PDF

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WO2018026545A1
WO2018026545A1 PCT/US2017/043284 US2017043284W WO2018026545A1 WO 2018026545 A1 WO2018026545 A1 WO 2018026545A1 US 2017043284 W US2017043284 W US 2017043284W WO 2018026545 A1 WO2018026545 A1 WO 2018026545A1
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humic acid
carbon
foam
polymer
solvent
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PCT/US2017/043284
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English (en)
Inventor
Aruna Zhamu
Bor Z. Jang
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Nanotek Instruments, Inc.
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Priority claimed from US15/228,133 external-priority patent/US11254616B2/en
Priority claimed from US15/228,345 external-priority patent/US9878303B1/en
Application filed by Nanotek Instruments, Inc. filed Critical Nanotek Instruments, Inc.
Publication of WO2018026545A1 publication Critical patent/WO2018026545A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • B01J20/205—Carbon nanostructures, e.g. nanotubes, nanohorns, nanocones, nanoballs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28042—Shaped bodies; Monolithic structures
    • B01J20/28045—Honeycomb or cellular structures; Solid foams or sponges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J20/28078—Pore diameter
    • B01J20/28083—Pore diameter being in the range 2-50 nm, i.e. mesopores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3007—Moulding, shaping or extruding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3078—Thermal treatment, e.g. calcining or pyrolizing
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/286—Treatment of water, waste water, or sewage by sorption using natural organic sorbents or derivatives thereof

Definitions

  • the present invention relates generally to the field of carbon/graphite foams and, more particularly, to a new form of porous carbon material herein referred to as an integral 3D humic acid-carbon hybrid foam and a method of producing same.
  • Carbon is known to have five unique crystalline structures, including diamond, fullerene (0-D nano graphitic material), carbon nano-tube or carbon nano-fiber (1-D nano graphitic material), graphene (2-D nano graphitic material), and graphite (3-D graphitic material).
  • the carbon nano-tube refers to a tubular structure grown with a single wall or multi-wall.
  • Carbon nano-tubes (CNTs) and carbon nano-fibers (CNFs) have a diameter on the order of a few nanometers to a few hundred nanometers.
  • Their longitudinal, hollow structures impart unique mechanical, electrical and chemical properties to the material.
  • the CNT or CNF is a one-dimensional nano carbon or 1-D nano graphite material.
  • CNTs are difficult to produce and are extremely expensive.
  • CNTs are known to be difficult to disperse in a solvent or water and difficult to mix with other materials. These characteristics have severely limited their scope of application.
  • a single-layer graphene sheet is composed of carbon atoms occupying a two-dimensional hexagonal lattice.
  • Multi-layer graphene is a platelet composed of more than one graphene plane.
  • Individual single-layer graphene sheets and multi-layer graphene platelets are herein collectively called nano graphene platelets (NGPs) or graphene materials.
  • NGPs include pristine graphene Docket ID - Humic 4 & 5 PCT
  • NGPs have been found to have a range of unusual physical, chemical, and mechanical properties. For instance, graphene was found to exhibit the highest intrinsic strength and highest thermal conductivity of all existing materials. Although practical electronic device applications for graphene (e.g., replacing Si as a backbone in a transistor) are not envisioned to occur within the next 5-10 years, its application as a nano filler in a composite material and an electrode material in energy storage devices is imminent. The availability of processable graphene sheets in large quantities is essential to the success in exploiting composite, energy, and other applications for graphene.
  • NGPs Nano Graphene Platelets
  • the first approach (Fig. 1) entails treating natural graphite powder with an intercalant and an oxidant (e.g., concentrated sulfuric acid and nitric acid, respectively) to obtain a graphite intercalation compound (GIC) or, actually, graphite oxide (GO).
  • an intercalant e.g., concentrated sulfuric acid and nitric acid, respectively
  • GAC graphite intercalation compound
  • GO graphite oxide
  • the inter- graphene spacing is increased to a value typically greater than 0.6 nm. This is the first expansion stage experienced by the graphite material during this chemical route.
  • the obtained GIC or GO is then subjected to further expansion (often referred to as exfoliation) using either a thermal shock exposure or a solution-based, ultrasonication-assisted graphene layer exfoliation approach.
  • the GIC or GO is exposed to a high temperature (typically 800-l,050°C) for a short period of time (typically 15 to 60 seconds) to exfoliate or expand the GIC or GO for the formation of exfoliated or further expanded graphite, which is typically in the form of a "graphite worm" composed of graphite flakes that are still
  • the expanded or exfoliated GO powder is dispersed in water or aqueous alcohol solution, which is subjected to ultrasonication. It is important to note that in these processes, ultrasonification is used after intercalation and oxidation of graphite (i.e., after first expansion) and typically after thermal shock exposure of the resulting GIC or GO (after second expansion).
  • the GO powder dispersed in water is subjected to an ion exchange or lengthy purification procedure in such a manner that the repulsive forces between ions residing in the inter-planar spaces overcome the inter-graphene van der Waals forces, resulting in graphene layer separations.
  • the resulting products are GO platelets that must undergo a further chemical reduction treatment to reduce the oxygen content.
  • the electrical conductivity of GO platelets remains much lower than that of pristine graphene.
  • the reduction procedure often involves the utilization of toxic chemicals, such as hydrazine.
  • the quantity of intercalation solution retained on the flakes after draining may range from 20 to 150 parts of solution by weight per 100 parts by weight of graphite flakes (pph) and more typically about 50 to 120 pph.
  • the residual intercalate species retained by the flakes decompose to produce various species of sulfuric and nitrous compounds (e.g., NO x and SO x ), which are undesirable.
  • the effluents require expensive remediation procedures in order not to have an adverse environmental impact.
  • Another process for producing graphene, in a thin film form is the catalytic chemical vapor deposition process.
  • This catalytic CVD involves catalytic decomposition of hydrocarbon gas (e.g. C 2 H 4 ) on Ni or Cu surface to form single-layer or few-layer graphene.
  • hydrocarbon gas e.g. C 2 H 4
  • Ni or Cu being the catalyst, carbon atoms obtained via
  • decomposition of hydrocarbon gas molecules at a temperature of 800-l,000°C are directly deposited onto Cu foil surface or precipitated out to the surface of a Ni foil from a Ni-C solid solution state to form a sheet of single-layer or few-layer graphene (less than 5 layers).
  • the Ni- or Cu-catalyzed CVD process does not lend itself to the deposition of more than 5 graphene planes (typically ⁇ 2 nm) beyond which the underlying Ni or Cu layer can no longer provide any catalytic effect.
  • the CVD graphene films are extremely expensive.
  • a foam or foamed material is composed of pores (or cells) and pore walls (a solid material).
  • the pores can be interconnected to form an open-cell foam.
  • graphene foam is composed of pores and pore walls that contain a graphene material.
  • the first method is the hydrothermal reduction of graphene oxide hydrogel that typically involves sealing graphene oxide (GO) aqueous suspension in a high-pressure autoclave and heating the GO suspension under a high pressure (tens or hundreds of atm) at a temperature typically in the range of 180-300°C for an extended period of time (typically 12-36 hours).
  • a useful reference for this method is given here: Y. Xu, et al. "Self- Assembled Graphene Hydrogel via a One-Step Hydrothermal Process," ACS Nano 2010, 4, 4324-4330.
  • the second method is based on a template-assisted catalytic CVD process, which involves CVD deposition of graphene on a sacrificial template (e.g. Ni foam).
  • a sacrificial template e.g. Ni foam
  • the graphene material conforms to the shape and dimensions of the Ni foam structure.
  • the Ni foam is then etched away using an etching agent, leaving behind a monolith of graphene skeleton that is essentially an open-cell foam.
  • Zongping Chen, et al. "Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapour deposition," Nature Materials, 10 (June 2011) 424-428.
  • the third method of producing graphene foam also makes use of a sacrificial material (e.g. colloidal polystyrene particles, PS) that is coated with graphene oxide sheets using a self- assembly approach.
  • a sacrificial material e.g. colloidal polystyrene particles, PS
  • PS polystyrene particles
  • Choi, et al. prepared chemically modified graphene (CMG) paper in two steps: fabrication of free-standing PS/CMG films by vacuum filtration of a mixed aqueous colloidal suspension of CMG and PS (2.0 ⁇ PS spheres), followed by removal of PS beads to generate 3D macro-pores [B. G. Choi, et al., "3D Macroporous Graphene
  • HA is an organic matter commonly found in soil and can be extracted from the soil using a base (e.g. KOH). HA can also be extracted, with a high yield, from a type of coal called leonardite, which is a highly oxidized version of lignite coal. HA extracted from leonardite contains a number of oxygenated groups (e.g. carboxyl groups) located around the edges of the graphene-like molecular center (SP 2 core of hexagonal carbon structure). This material is slightly similar to graphene oxide (GO) which is produced by strong acid oxidation of natural graphite. HA has a typical oxygen content of 5% to 42% by weight (other major elements being carbon and hydrogen).
  • GO graphene oxide
  • HA after chemical or thermal reduction, has an oxygen content of 0.01% to 5% by weight.
  • humic acid refers to the entire oxygen content range, from 0.01% to 42% by weight.
  • the reduced humic acid is a special type of HA that has an oxygen content of 0.01% to 5% by weight.
  • the present invention is directed at a new class of graphene-like 2D materials (i.e. humic acid) that surprisingly can be used in a combination with carbon to form a hybrid foam.
  • humic acid graphene-like 2D materials
  • Another object is to provide a cost-effective method of producing such a nano carbon foam (specifically, integral 3D humic acid-carbon hybrid foam) in large quantities.
  • This method or process does not involve the use of an environmentally unfriendly chemical. This method enables the flexible design and control of the porosity level and pore sizes.
  • Yet another object of the present invention is to provide (a) a reduced humic acid-based hybrid foam that contains essentially all carbon only ( ⁇ 5% by weight of non-carbon content, preferably ⁇ 1 %, and further preferably ⁇ 0.1%) and preferably have a meso-scaled pore size range (2-50 nm); and (b) humic acid foams that contain at least 5% by weight (typically from 5% to 42% by weight and most typically from 5% to 20%) of non-carbon elements that can be used for a broad array of applications.
  • Another object of the present invention is to provide products (e.g. devices) that contain an integral 3D humic acid-carbon foam of the present invention and methods of operating these products.
  • the present invention provides an integral 3D humic acid-carbon hybrid foam composed of multiple pores and pore walls, wherein the pore walls contain single-layer or few-layer humic acid sheets chemically bonded by a carbon material at their edges and have a carbon material-to- humic acid weight ratio from 1/200 to 1/2, wherein the few-layer humic acid sheets have 2-10 layers of stacked substantially hexagonal carbon planes having an inter-plane spacing d 0 02 from 0.3354 nm to 0.40 nm as measured by X-ray diffraction and said single-layer or few-layer humic acid sheets contain 0.01% to 25% by weight of non-carbon elements, wherein humic acid is selected from oxidized humic acid, reduced humic acid, fluorinated humic acid, chlorinated humic acid, brominated humic acid, iodized humic acid, hydrogenated humic acid, nitrogenated humic acid, doped humic acid, chemically
  • the hybrid foam typically has a density from 0.005 to 1.7 g/cm 3 , a specific surface area from 50 to 3,200 m 2 /g, a thermal conductivity of at least 200 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 2,000 S/cm per unit of specific gravity.
  • the hybrid foam has a density from 0.01 to 1.7 g/cm 3 or an average pore size from 2 nm to 50
  • the foam has a specific surface area from 200 to 3,000 m 2 /g or a density from 0.1 to 1.2 g/cm 3 .
  • the integral 3D humic acid-carbon hybrid foam contains a content of non-carbon elements in the range of 0.01% to 20% by weight and the non-carbon elements include an element selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron.
  • the pore walls contain fluorinated humic acid and said foam contains a fluorine content from 0.01% to 15% by weight. In certain other embodiments, the pore walls contain oxidized humic acid and the foam contains an oxygen content from 0.01% to 20% by weight.
  • the 3D humic acid-carbon hybrid foam can be in a continuous-length roll sheet form having a thickness from 100 nm to 10 cm and a length of at least 2 meters and may be produced by a roll-to-roll process.
  • the 3D humic acid-carbon hybrid foam has an oxygen content or non-carbon content less than 1% by weight, and said pore walls have an inter-planar spacing less than 0.35 nm, a thermal conductivity of at least 250 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 2,500 S/cm per unit of specific gravity.
  • the hybrid foam has an oxygen content or non-carbon content less than 0.01% by weight and the pore walls contain stacked hexagonal carbon planes having an inter-planar spacing less than 0.34 nm, a thermal conductivity of at least 300 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 3,000 S/cm per unit of specific gravity.
  • the foam has an oxygen content or non-carbon content no greater than 0.01%) by weight and the pore walls contain stacked hexagonal carbon planes having an inter- planar spacing less than 0.336 nm, a thermal conductivity of at least 350 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 3,500 S/cm per unit of specific gravity. Still more preferably, the foam has pore walls containing stacked hexagonal carbon planes having an inter-planar spacing less than 0.336 nm, a thermal conductivity greater than 400 W/mK per unit of specific gravity, and/or an electrical conductivity greater than 4,000 S/cm per
  • the pore walls contain stacked hexagonal carbon planes having an inter-planar spacing less than 0.337 nm and a mosaic spread value less than 1.0.
  • the pore walls contain a 3D network of interconnected hexagonal carbon planes, or the foam contains meso-scaled pores having a pore size from 2 nm to 50 nm.
  • the present invention also provides an oil-removing or oil-separating device containing the 3D humic acid-carbon hybrid foam as an oil-absorbing element. Also provided is a solvent- removing or solvent-separating device containing the 3D humic acid-carbon hybrid foam of as a solvent-absorbing or solvent-separating element.
  • the invention also provides a method to separate oil from water.
  • the method comprises the steps of: (a) providing an oil-absorbing element comprising the integral 3D humic acid- carbon hybrid foam; (b) contacting an oil-water mixture with the element, which absorbs the oil from the mixture; (c) retreating the element from the mixture and extracting the oil from the element; and (d) reusing the element.
  • the invention provides a method to separate an organic solvent from a solvent-water mixture or from a multiple-solvent mixture.
  • the method comprises the steps of: (a) providing an organic solvent-absorbing or solvent-separating element comprising the integral 3D humic acid-carbon hybrid foam; (b) bringing the element in contact with an organic solvent- water mixture or a multiple-solvent mixture containing a first solvent and at least a second solvent; (c) allowing the element to absorb the organic solvent from the mixture or separate the first solvent from the at least second solvent; (d) retreating the element from the mixture and extracting the organic solvent or first solvent from the element; and (e) reusing the element.
  • thermal management device containing the 3D integral humic acid- carbon hybrid foam as a heat spreading or heat dissipating element.
  • the thermal management device may contain a device selected from a heat exchanger, heat sink, heat pipe, high- conductivity insert, conductive plate between a heat sink and a heat source, heat-spreading component, heat-dissipating component, thermal interface medium, or thermoelectric or Peltier cooling device.
  • the present invention provides a method of producing an integral 3D humic acid-carbon hybrid foam.
  • This method is stunningly simple.
  • the method comprises: (A) forming a solid shape of humic acid-polymer particle mixture; and (B) pyrolyzing the solid shape of humic acid- polymer particle mixture to thermally reduce said humic acid into reduced humic acid sheets and, essentially concurrently, thermally convert the polymer into pores and carbon or graphite that bonds reduced humic acid sheets to form the integral 3D humic acid-carbon hybrid foam.
  • step (A) comprises: (i) dispersing humic acid in water or a solvent to form a suspension and dispersing multiple polymer particles in this suspension to form a slurry; and (ii) dispensing the slurry and removing water or solvent to form a solid shape of humic acid-polymer particle mixture.
  • step (A) enables humic acid molecules or sheets to wrap around polymer particles (fully coated and embraced by humic acid).
  • the integral 3D humic acid-carbon hybrid foam is in a film, sheet, paper, filament, rod, powder, ingot, or bulk form of essentially any reasonable shape.
  • the polymer particles preferably include plastic or rubber beads, pellets, spheres, wires, fibers, filaments, discs, ribbons, or rods, having a diameter or thickness from 10 nm to 10 mm (preferably from 100 nm to 1 mm).
  • the polymer particles are selected from solid particles of a thermoplastic, thermoset resin, rubber, semi-penetrating network polymer, penetrating network polymer, natural polymer, or a combination thereof.
  • the polymer particles contain a high carbon-yield polymer selected from phenolic resin, poly furfuryl alcohol, polyacrylonitrile, polyimide, polyamide, polyoxadiazole, polybenzoxazole, polybenzobisoxazole, polythiazole, polybenzothiazole, polybenzobisthiazole, poly(p-phenylene vinylene), polybenzimidazole, polybenzobisimidazole, a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • a high carbon-yield polymer selected from phenolic resin, poly furfuryl alcohol, polyacrylonitrile, polyimide, polyamide, polyoxadiazole, polybenzoxazole, polybenzobisoxazole, polythiazole, polybenzothiazole, poly(p-phenylene vinylene), polybenzimidazole, polybenzobisimidazole, a copolymer thereof, a polymer blend thereof, or a combination thereof
  • the polymer particles contain a low carbon-yield polymer selected from polyethylene, polypropylene, polybutylene, polyvinyl chloride, polycarbonate,
  • ABS acrylonitrile-butadiene
  • polyester polyvinyl alcohol, poly vinylidiene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene oxide (PPO), poly methyl methacrylate
  • PMMA polymethyl methacrylate copolymer
  • a copolymer thereof a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • the step of pyrolyzing can include carbonizing the polymer particles at a temperature from 200°C to 2,500°C to obtain reduced humic acid-carbon foam, or carbonizing the polymer particles at a temperature from 200°C to 2,500°C to obtain reduced humic acid-carbon foam and then graphitizing the reduced humic acid-carbon foam from
  • the shaping step includes melting the polymer particles to form a polymer melt mixture with humic acid sheets dispersed therein, forming the polymer melt mixture into a desired shape and solidifying the desired shape into a humic acid-polymer composite structure.
  • the shaping step includes dissolving the polymer particles in a solvent to form a polymer solution mixture with humic acid sheets dispersed therein, forming the polymer solution mixture into a desired shape, and removing the solvent to solidify the desired shape into a humic acid-polymer composite structure.
  • the shaping step includes forming the humic acid-coated polymer particles into a composite shape selected from a rod, sheet, film, fiber, powder, ingot, or block form.
  • the shaping step includes compacting humic acid-coated polymer particles into a porous green compact having macroscopic pores and then infiltrating or impregnating the pores with an additional carbon source material selected from a petroleum pitch, coal tar pitch, an aromatic organic material, a monomer, an organic polymer, or a combination thereof.
  • the organic polymer may contain a high carbon-yield polymer selected from phenolic resin, poly furfuryl alcohol, polyacrylonitrile, polyimide, polyamide,
  • polyoxadiazole polybenzoxazole, polybenzobisoxazole, polythiazole, polybenzothiazole, polybenzobisthiazole, poly(p-phenylene vinylene), polybenzimidazole, polybenzobisimidazole, a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • the shaping step includes forming a mass of said graphene-
  • the compacted object may be in a form selected from a rod, sheet, film, fiber, powder, ingot, or block.
  • FIG. 1 A flow chart showing the most commonly used prior art process of producing highly oxidized graphene (NGPs) that entails tedious chemical oxidation/intercalation, rinsing, and high-temperature exfoliation procedures.
  • NTPs highly oxidized graphene
  • FIG. 2 A flow chart showing the presently invented process for producing integral 3D humic acid-carbon hybrid foam.
  • FIG. 3 Schematic of the heat-induced conversion of polymer into carbon, which bonds humic acid sheets together to form a 3D HA-carbon hybrid foam.
  • the compacted structure of humic acid-coated polymer particles is converted into a highly porous structure.
  • FIG. 4(A) Thermal conductivity values vs. specific gravity of a 3D integral HA-carbon foam produced by the presently invented process, a meso-phase pitch-derived graphite foam, and a Ni foam-template assisted CVD graphene foam.
  • FIG. 4(B) Thermal conductivity values of 3D HA-carbon foam and the hydrothermally reduced
  • FIG. 5 Thermal conductivity values of 3D HA-carbon hybrid foam and pristine graphene foam (prepared by casting with a blowing agent and then heat treating) plotted as a function of the final (maximum) heat treatment temperature.
  • FIG. 6 Electrical conductivity values of 3D HA-carbon foam and the hydrothermally reduced GO graphene foam.
  • FIG. 7 The amount of oil absorbed per gram of integral 3D HA-carbon hybrid foam, plotted as a function of the oxygen content in the foam having a porosity level of approximately 98%
  • FIG. 8 The amount of oil absorbed per gram of integral 3D HA-carbon hybrid foam, plotted as a function of the porosity level (given the same oxygen content).
  • FIG. 9 The amount of chloroform absorbed out of a chloroform -water mixture, plotted as a
  • FIG. 10 Schematic of heat sink structures (2 examples).
  • HA is an organic matter commonly found in soil and can be extracted from the soil using a base (e.g. KOH). HA can also be extracted from a type of coal called leonardite, which is a highly oxidized version of lignite coal. HA extracted from leonardite contains a number of oxygenated groups (e.g. carboxyl groups) located around the edges of the graphene- like molecular center (SP 2 core of hexagonal carbon structure). This material is slightly similar to graphene oxide (GO) which is produced by strong acid oxidation of natural graphite. HA has a typical oxygen content of 5% to 42% by weight (other major elements being carbon, hydrogen, and nitrogen).
  • GO graphene oxide
  • the present invention provides an integral 3D humic acid-carbon hybrid foam and a method of producing such a hybrid foam.
  • This method is stunningly simple, but effective, of low cost, and environmentally benign.
  • the method comprises: (A) forming a solid shape of humic acid-polymer particle mixture; and (B) pyrolyzing the solid shape of humic acid-polymer particle mixture to thermally reduce humic acid into reduced humic acid sheets and, essentially concurrently, thermally convert the polymer into pores and carbon or graphite that bonds reduced humic acid sheets to form the integral 3D humic acid-carbon hybrid foam.
  • step (A) comprises: (i) dispersing humic acid in water or a solvent to form a suspension (or solution) and dispersing multiple polymer particles in this suspension or solution to form a slurry; and (ii) dispensing the slurry and removing water or solvent to form a solid shape of humic acid-polymer particle mixture.
  • humic acid HA
  • polar solvents such as methanol and ethanol.
  • the solid shape is transformed into an integral 3D humic acid-carbon hybrid foam, which can be in a film, sheet, paper, filament, rod, powder, ingot, or bulk form of essentially any desired shape.
  • the method can include forming humic acid-embraced particles into a desired shape of humic acid-polymer composite structure.
  • This forming step can be as simple as a compacting step that just mechanically packs humic acid-coated or embedded polymer particles into a desired shape.
  • this forming step can entail melting the polymer particles to form a polymer matrix with humic acid molecules or sheets dispersed therein.
  • a humic acid- polymer structure can be in any practical shape or dimensions (fiber, rod, plate, cylinder, or any regular shape or odd shape).
  • the humic acid-polymer compact or composite structure is then pyrolyzed to thermally reduce humic acid into reduced humic acid (RHA) and, concurrently, thermally convert the polymer into carbon or graphite that bonds the reduced humic acid sheets together to form the integral 3D RHA-carbon hybrid foam.
  • RHA reduced humic acid
  • the non-carbon content of RHA can be varied between approximately 0.01% by weight and 5% by weight, depending upon the maximum heat treatment temperature involved.
  • the high carbon-yield polymer may be selected from phenolic resin, poly furfuryl alcohol, polyacrylonitrile, polyimide, polyamide, polyoxadiazole, polybenzoxazole,
  • the polymer can contain a low carbon-yield polymer selected from polyethylene, polypropylene, polybutylene, polyvinyl chloride, polycarbonate, acrylonitrile-butadiene (ABS), polyester, polyvinyl alcohol, poly vinylidiene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene oxide (PPO), poly methyl methacrylate (PMMA), a copolymer thereof, a polymer blend thereof, or a combination thereof.
  • a low carbon-yield polymer selected from polyethylene, polypropylene, polybutylene, polyvinyl chloride, polycarbonate, acrylonitrile-butadiene (ABS), polyester, polyvinyl alcohol, poly vinylidiene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyphenylene oxide (PPO), poly methyl methacrylate (PMMA), a copolymer thereof, a polymer blend thereof, or a combination thereof
  • HA-carbon hybrid foam is composed of integral 3D network of carbon-bonded HA sheets, enabling continuous transport of electrons and phonons (quantized lattice vibrations) between HA sheets or domains without interruptions.
  • the carbon phase can get graphitized to further increase both the electric conductivity and thermal conductivity.
  • the amount of non-carbon elements is also decreased to typically below 1% by weight (down to 0.01%) if the graphitization time exceeds 1 hour.
  • an organic polymer typically contains a significant amount of non- carbon elements, which can be reduced or eliminated via heat treatments.
  • pyrolyzation of a polymer causes the formation and evolution of volatile gas molecules, such as C0 2 and H 2 0, which lead to the formation of pores in the resulting polymeric carbon phase.
  • volatile gas molecules such as C0 2 and H 2 0
  • such pores also have a high tendency to get collapsed if the polymer is not constrained when being carbonized (the carbon structure can shrink while non-carbon elements are being released).
  • a certain desired degree of hydrophilicity can be imparted to the pore walls of the humic acid -carbon hybrid foam if the non-carbon element content (H and O) is from 2 to 20% by weight.
  • the HA-carbon foam can be subjected to graphitization treatment at a temperature higher than 2,500°C.
  • the resulting material is particularly useful for thermal management applications (e.g. for use to make a finned heat sink, a heat exchanger, or a heat spreader).
  • the HA-carbon foam may be subjected to compression during and/or after the graphitization treatment. This operation enables us to adjust the graphene sheet orientation and the degree of porosity.
  • X-ray diffraction patterns were obtained with an X-ray diffractometer equipped with CuKcv radiation. The shift and broadening of diffraction peaks were calibrated using a silicon powder standard.
  • 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 produced with a heat treatment temperature (HTT) no less than 2,500°C). However, some values are in the range of 0.4-0.7 if the HTT is between 1,500 and 2,500°C, and in the range of 0.7-1.0 if the HTT is between 300 and 1,500°C.
  • HTT heat treatment temperature
  • humic acid-carbon foam walls are composed of several large graphene planes (with length/width typically » 20 nm, more typically » 100 nm, often » 1 ⁇ , and, in many cases, » 10 ⁇ ). This is quite unexpected since the lateral dimensions (length and width) of original humic acid sheets or molecules, prior to being heat treated, are typically ⁇ 20 nm and more typically ⁇ 10 nm. This implies that a plurality of HA sheets or molecules can be merged edge to edge through covalent bonds with one another, into a larger (longer or wider) sheet.
  • the integral 3D HA-carbon hybrid foam is composed of multiple pores and pore walls, wherein the pore walls contain single-layer or few-layer HA sheets chemically bonded by a carbon material having a carbon material-to-HA weight ratio from 1/100 to 1/2, wherein the few- layer HA sheets have 2-10 layers of stacked graphene-like HA planes having an inter-plane spacing doo 2 from 0.3354 nm to 0.36 nm as measured by X-ray diffraction and the single-layer or few-layer graphene-like HA sheets contain 0.01% to 25% by weight of non-carbon elements (more typically ⁇ 15%).
  • a plurality of single-layer or few-layer HA sheets embracing the underlying polymer particles can overlap with one another to form a stack of graphene-like sheets.
  • the stack can have a thickness greater than 5 nm and, in some cases, greater than 10 nm.
  • the integral 3D HA-carbon hybrid foam typically has a density from 0.001 to 1.7 g/cm 3 , a specific surface area from 50 to 3,000 m 2 /g, a thermal conductivity of at least 200 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 2,000 S/cm per unit of specific gravity.
  • the pore walls contain stacked graphene-like RHA planes having an inter-planar spacing doo 2 from 0.3354 nm to 0.40 nm as measured by X-ray diffraction.
  • HA sheets can be merged edge to edge through covalent bonds with one another, into an integrated RHA entity.
  • the gaps between the free ends of those unmerged sheets or shorter merged sheets are bonded by the carbon phase converted from the polymer particles. Due to these unique chemical composition (including oxygen or hydrogen content, etc.), morphology, crystal structure (including inter-planar spacing), and structural features (e.g.
  • the HA-carbon hybrid foam has a unique combination of outstanding thermal conductivity, electrical conductivity, mechanical strength, and stiffness (elastic modulus).
  • the integral 3D HA-carbon hybrid foam an ideal element for a broad array of engineering and biomedical applications.
  • the graphene-carbon foam can be used in the following applications:
  • the HA-carbon hybrid foam being compressible and of high thermal conductivity, is ideally suited for use as a thermal interface material (TIM) that can be implemented between a heat source and a heat spreader or between a heat source and a heat sink.
  • TIM thermal interface material
  • the hybrid foam can be used as a heat spreader per se due to its high thermal
  • the hybrid foam can be used as a heat sink or heat dissipating material due to his high heat-spreading capability (high thermal conductivity) and high heat-dissipating capability (large number of surface pores inducing massive air-convection micro or nano channels).
  • the light weight low density adjustable between 0.001 and 1.8 g/cm 3 ), high thermal conductivity per unit specific gravity or per unit of physical density, and high structural integrity (HA sheets being bonded by carbon) make this hybrid foam an ideal material for a durable heat exchanger.
  • the HA-carbon hybrid foam-based thermal management or heat dissipating devices include a heat exchanger, a heat sink (e.g. finned heat sink), a heat pipe, high-conductivity insert, thin or thick conductive plate (between a heat sink and a heat source), thermal interface medium (or thermal interface material, TIM), thermoelectric or Peltier cooling plate, etc.
  • a heat exchanger e.g. finned heat sink
  • a heat pipe e.g. finned heat sink
  • high-conductivity insert e.g. finned heat sink
  • thin or thick conductive plate between a heat sink and a heat source
  • thermal interface medium or thermal interface material, TIM
  • thermoelectric or Peltier cooling plate e.g., thermoelectric or Peltier cooling plate, etc.
  • a heat exchanger is a device used to transfer heat between one or more fluids; e.g. a gas and a liquid separately flowing in different channels.
  • the fluids are typically separated by a solid wall to prevent mixing.
  • the presently invented graphene-carbon hybrid foam material is an ideal material for such a wall provided the foam is not a totally open-cell foam that allows for mixing of fluids.
  • the presently invented method enables production of both open-cell and closed-cell foam structures. The high surface pore areas enable dramatically faster exchange of heats between the two or multiple fluids.
  • Heat exchangers are widely used in refrigeration systems, air conditioning units, heaters, power stations, chemical plants, petrochemical plants, petroleum refineries, natural-gas processing, and sewage treatment.
  • a well-known example of a heat exchanger is found in an internal combustion engine in which a circulating engine coolant flows through radiator coils while air flows past the coils, which cools the coolant and heats the incoming air.
  • the solid walls e.g. that constitute the radiator coils
  • heat exchangers There are many types of heat exchangers that are commercially available: shell and tube heat exchanger, plate heat exchangers, plate and shell heat exchanger, adiabatic wheel heat exchanger, plate fin heat exchanger, pillow plate heat exchanger, fluid heat exchangers, waste heat recovery units, dynamic scraped surface heat exchanger, phase-change heat exchangers, direct contact heat exchangers, and microchannel heat exchangers. Every one of these types of heat exchangers can take advantage of the exceptional high thermal conductivity and specific surface area of the presently invented foam material.
  • the presently invented solid HA-carbon foam can also be used in a heat sink. Heat sinks are widely used in electronic devices for heat dissipation purposes.
  • the central processing unit (CPU) and battery in a portable microelectronic device are well-known heat sources.
  • a metal or graphite object e.g. Cu foil or graphite foil
  • this object helps to spread the heat to an external surface or outside air (primarily by conduction and convection and to a lesser extent by radiation).
  • a thin thermal interface material TIM mediates between the hot surface of the heat source and a heat spreader or a heat-spreading surface of a heat sink.
  • TIM thin thermal interface material
  • a heat sink usually consists of a high-conductivity material structure with one or more flat surfaces to ensure good thermal contact with the components to be cooled, and an array of comb or fin like protrusions to increase the surface contact with the air, and thus the rate of heat dissipation.
  • a heat sink may be used in conjunction with a fan to increase the rate of airflow over the heat sink.
  • a heat sink can have multiple fins (extended or protruded surfaces) to improve heat transfer. In electronic devices with limited amount of space, the shape/arrangement of fins must be optimized such that the heat transfer density is maximized.
  • cavities inverted fins may be embedded in the regions formed between adjacent fins. These cavities are effective in extracting heat from a variety of heat generating bodies to a heat sink.
  • an integrated heat sink comprises a heat collection member (core or base) and at least one heat dissipation member (e.g. a fin or multiple fins) integral to the heat collection member (base) to form a finned heat sink.
  • the fins and the core are naturally connected or integrated together into a unified body without using an externally applied adhesive or mechanical fastening means to connect the fins to the core.
  • the heat collection base has a surface in thermal contact with a heat source (e.g. a LED), collects heat from this heat source, and dissipates heat through the fins into the air.
  • FIG. 10 provides a schematic of two heat sinks: 300 and 302.
  • the first one contains a heat collection member (or base member) 304 and multiple fins or heat dissipation members (e.g. fin 306) connected to the base member 304.
  • the base member 304 is shown to have a heat collection surface 314 intended to be in thermal contact with a heat source.
  • the heat dissipation member or fin 306 is shown to have at least a heat dissipation surface 320.
  • a particularly useful embodiment is an integrated radial heat sink 302 comprising a radial finned heat sink assembly that comprises: (a) a base 308 comprising a heat collection surface 318; and (b) a plurality of spaced parallel planar fin members (e.g. 310, 312 as two examples) supported by or integral with the base 308, wherein the planar fin members (e.g. 310) comprise the at least one heat dissipation surface 322. Multiple parallel planar fin members are preferably equally spaced.
  • the presently invented HA-carbon hybrid foam being highly elastic and resilient, is itself a good thermal interface material and a highly effective heat spreading element as well.
  • this high-conductivity foam can also be used as an inserts for electronic cooling and for enhancing the heat removal from small chips to a heat sink. Because the space occupied by high conductivity materials is a major concern, it is a more efficient design to make use of high conductivity pathways that can be embedded into a heat generating body.
  • the elastic and highly conducting solid graphene foam herein disclosed meets these requirements perfectly.
  • the high elasticity and high thermal conductivity make the presently invented solid HA- carbon hybrid foam a good conductive thick plate to be placed as a heat transfer interface between a heat source and a cold flowing fluid (or any other heat sink) to improve the cooling
  • the heat source is cooled under the thick HA-carbon foam plate instead of being cooled in direct contact with the cooling fluid.
  • the thick plate of HA- carbon foam can significantly improve the heat transfer between the heat source and the cooling fluid by way of conducting the heat current in an optimal manner. No additional pumping power and no extra heat transfer surface area are required.
  • a heat pipe is a heat transfer device that uses evaporation and condensation of a two-phase working fluid or coolant to transport large quantities of heat with a very small difference in temperature between the hot and cold interfaces.
  • a conventional heat pipe consists of sealed hollow tube made of a thermally conductive metal such as Cu or Al, and a wick to return the working fluid from the evaporator to the condenser.
  • the pipe contains both saturated liquid and vapor of a working fluid (such as water, methanol or ammonia), all other gases being excluded.
  • a working fluid such as water, methanol or ammonia
  • the heat pipe for electronics thermal management can have a solid graphene foam envelope and wick, with water as the working fluid.
  • HA-carbon/ methanol may be used if the heat pipe needs to operate below the freezing point of water, and HA-carbon/ammonia heat pipes may be used for electronics cooling in space.
  • Peltier cooling plates operate on the Peltier effect to create a heat flux between the junction of two different conductors of electricity by applying an electric current. This effect is commonly used for cooling electronic components and small instruments. In practice, many such junctions may be arranged in series to increase the effect to the amount of heating or cooling required.
  • the solid graphene foam may be used to improve the heat transfer efficiency.
  • the solid HA-carbon foam can be made to contain microscopic pores ( ⁇ 2 nm) or meso- scaled pores having a pore size from 2 nm to 50 nm.
  • the solid HA-carbon hybrid foam can also be made to contain micron-scaled pores (1-500 ⁇ ). Based on well-controlled pore size alone, the instant HA-carbon foam can be an exceptional filter material for air or water filtration.
  • the humic acid (HA) pore wall chemistry and carbon phase chemistry can be independently controlled to impart different amounts and/or types of functional groups to either or both of the HA sheets and the carbon binder phase (e.g. as reflected by the percentage of O, F, N, H, etc. in the foam).
  • the concurrent or independent control of both pore sizes and chemical functional groups at different sites of the internal structure provide unprecedented flexibility or highest degree of freedom in designing and making HA-carbon hybrid foams that exhibit many unexpected properties, synergistic effects, and some unique combination of properties that are normally considered mutually exclusive (e.g. some part of the structure is hydrophobic and other part hydrophilic; or the foam structure is both hydrophobic and oleophilic).
  • a surface or a material is said to be hydrophobic if water is repelled from this material or surface and that a droplet of water placed on a hydrophobic surface or material will form a large contact angle.
  • a surface or a material is said to be oleophilic if it has a strong affinity for oils and not for water. The present method allows for precise control over
  • the present invention also provides an oil-removing, oil-separating, or oil-recovering device, which contains the presently invented 3D HA-carbon hybrid foam as an oil-absorbing or oil-separating element. Also provided is a solvent-removing or solvent-separating device containing the 3D HA-carbon hybrid foam as a solvent-absorbing element.
  • a major advantage of using the instant HA-carbon hybrid foam as an oil-absorbing element is its structural integrity. Due to the notion that HA sheets are chemically bonded by the carbon material, the resulting foam would not get disintegrated upon repeated oil absorption operations. In contrast, we have discovered that graphene-based oil-absorbing elements prepared by hydrothermal reduction, vacuum-assisted filtration, or freeze-drying get disintegrated after absorbing oil for 2 or 3 times. There is just nothing (other than weak van der Waals forces existing prior to first contact with oil) to hold these otherwise separated graphene sheets together. Once these graphene sheets are wetted by oil, they no longer are able to return to the original shape of the oil -absorbing element.
  • Another major advantage of the instant technology is the flexibility in designing and making oil-absorbing elements that are capable of absorbing oil up to an amount as high as 400
  • the invention also provides a method to separate/recover oil from an oil-water mixture
  • the method comprises the steps of (a) providing an oil-absorbing element comprising an integral HA-carbon hybrid foam; (b) contacting an oil-water mixture with the element, which absorbs the oil from the mixture; and (c) retreating the oil-absorbing element from the mixture and extracting the oil from the element.
  • the method comprises a further step of (d) reusing the element.
  • the invention provides a method to separate an organic solvent from a solvent-water mixture or from a multiple-solvent mixture.
  • the method comprises the steps of (a) providing an organic solvent-absorbing element comprising an integral HA-carbon hybrid foam; (b) bringing the element in contact with an organic solvent-water mixture or a multiple-solvent mixture containing a first solvent and at least a second solvent; (c) allowing this element to absorb the organic solvent from the mixture or absorb the first solvent from the at least second solvent; and (d) retreating the element from the mixture and extracting the organic solvent or first solvent from the element.
  • the method contains an additional step (e) of reusing the solvent-absorbing element.
  • One experiment entails dispersing 5% by weight of PP powder in a humic acid-water solution (5% HA) to obtain a slurry. The slurry was then spray-dried to form powder of HA- coated PP particles. The HA-coated PP particles were then compacted in a mold cavity to form a green compact, which was then heat-treated in a sealed crucible at 350°C and then at 600°C for 2
  • polypropylene PP
  • HA-carbon hybrid foam production are not limited to PP. It could be any polymer
  • thermosetting resins such as epoxide and imide-based oligomers or rubber
  • a particulate form fine powder particles having a diameter preferably in the range of 10 nm - 10 ⁇ , further preferably 20 nm-1 ⁇ .
  • un-cured or partially cured thermosetting resins can be made into a particle form at room temperature or lower (e.g. cryogenic temperature).
  • room temperature or lower e.g. cryogenic temperature
  • even partially cured thermosetting resin particles can be used as solid polymer particles.
  • EXAMPLE 2 Humic acid-carbon hybrid foam using ABS as the solid polymer particles
  • PAN fiber segments (2 mm long as the polymer particles) were dispersed in a HA-methanol solution to form a slurry, which was oven dried to form a mass of HA-coated PAN fiber powder.
  • the HA-coated PAN fibers were then compacted and melted together to form several composite films.
  • the films were subjected to heat treatments at 250°C for 1 hour (in room air), 350°C for 2 hours, and 1,000°C for 2 hours (under an argon gas atmosphere) to obtain RHA-carbon foam layers.
  • Half of the carbonized foam layers were then heated to 2,850°C and maintained at this temperature for 0.5 hours to obtain graphitized RHA- carbon foam.
  • EXAMPLE 4 Particles of cured phenolic resin as the polymer particles
  • Particles of cured phenolic resin were dispersed in a HA-water suspension to form a slurry, which was spray-dried to form a slurry.
  • a mass of HA-coated resin particles was compressed to form a green compact, which was then infiltrated with a small amount of petroleum pitch. Separately, another green compact of HA-coated resin particles was prepared
  • the experiment began with preparation of micron-sized rubber particles.
  • a mixture of methylhydro dimethyl-siloxane polymer (20 g) and polydimethylsiloxane, vinyldimethyl terminated polymer (30 g) was obtained by using a honiogenizer under ambient conditions for I minute.
  • Tween 80 (4.6 g) was added and the mixture was homogenized for 20 seconds.
  • Platinum-divinyltetramethyldisiloxane complex (0.5 g in 15 g methanol) was added and mixed for 10 seconds. This mixture was added to 350 g of distilled water and a stable latex was obtained by homogenization for 15 minutes. The latex was heated to 60°C for 15 hours.
  • Doc #100005 latex was then de-emulsified with anhydrous sodium sulfate (20 g) and the silicone rubber particles were obtained by filtration under a vacuum, washing with distilled water, and drying under vacuum at 25°C.
  • the particle size distribution of the resulting rubber particles was 3-1 1 ⁇ .
  • Humic acid-coated rubber particles were obtained by spray-drying of HA-water-rubber slurry.
  • the HA-coated rubber particles were then mixed with 5% by wt. of petroleum pitch (as a binder) and mechanically compacted together to form several composite sheets.
  • the composite sheets were then subjected to heat treatments at 350°C for 1 hour, 650°C for 2 hours, and 1,000°C for 1 hour in a tube furnace to obtain HA-carbon foam layers.
  • EXAMPLES 7 Preparation of fluorinated HA-carbon foams
  • a sheet of HA-carbon hybrid was fluorinated by vapors of chlorine trifluoride in a sealed autoclave reactor to yield fluorinated HA-carbon hybrid film.
  • Different durations of fluorination time were allowed for achieving different degrees of fluorination.
  • Sheets of fluorinated HA-carbon foam were then separately immersed in containers each containing a chloroform-water mixture. We observed that these foam sheets selectively absorb chloroform from water and the amount of chloroform absorbed increases with the degree of fluorination until the fluorine content reaches 7.2% by wt. (FIG. 9).
  • Example 3 Several pieces of HA-carbon foam prepared in Example 3 were immersed in a 30% H 2 0 2 -water solution for a period of 2-48 hours to obtain oxidized HA-carbon foams, having a controlled oxygen content of 2-25% by weight.
  • Some oxidized HA-carbon foam samples were mixed with different proportions of urea and the mixtures were heated in a microwave reactor (900 W) for 0.5 to 5 minutes. The products were washed several times with deionized water and vacuum dried. The products obtained were nitrogenated HA-carbon foam. The nitrogen contents were from 3% to 17.5 wt. %, as measured by elemental analysis.
  • oxidized HA-carbon hybrid foam structures are particularly effective as an absorber of oil from an oil-water mixture (i.e. oil spilled on water and
  • the integral 3D HA (0-15% by wt. oxygen)-carbon foam structures are both hydrophobic and oleophilic (FIG. 7).
  • a surface or a material is said to be hydrophobic if water is repelled from this material or surface and that a droplet of water placed on a hydrophobic surface or material will form a large contact angle.
  • a surface or a material is said to be oleophilic if it has a strong affinity for oils and not for water.
  • COMPARATIVE EXAMPLE 1 Graphene via Hummer's Process and carbonization of graphene-polymer composite
  • Graphite oxide as prepared by oxidation of graphite flakes with sulfuric acid, nitrate, and permanganate according to the method of Hummers [US Pat. No. 2,798,878, Jul. 9, 1957]. Upon completion of the reaction, the mixture was poured into deionized water and filtered. The graphite oxide was repeatedly washed in a 5% solution of HC1 to remove most of the sulphate ions. The sample was then washed repeatedly with deionized water until the pH of the filtrate was neutral. The slurry was spray-dried and stored in a vacuum oven at 60° C. for 24 hours. The interlayer spacing of the resulting laminar graphite oxide was determined by the Debey-Scherrer X-ray technique to be approximately 0.73nm (7.3 A). A sample of this material was
  • MCMBs Meso-carbon microbeads
  • MCMB 10 grams were intercalated with an acid solution (sulfuric acid, nitric acid, and potassium permanganate at a ratio of 4: 1 :0.05) for 48-96 hours. Upon completion of the reaction, the mixture was poured into deionized water and filtered. The intercalated MCMBs were repeatedly washed in a 5% solution of HC1 to remove most of the sulphate ions. The sample was then washed repeatedly with deionized water until the pH of the filtrate was no less than 4.5. The slurry was then subjected ultrasoni cation for 10-100 minutes to produce GO suspensions. TEM and atomic force microscopic studies indicate that most of the GO sheets were single-layer graphene when the oxidation treatment exceeded 72 hours, and 2- or 3-layer graphene when the oxidation time was from 48 to 72 hours.
  • the GO sheets contain oxygen proportion of approximately 35%-47% by weight for oxidation treatment times of 48-96 hours.
  • GO sheets were suspended in water. Baking soda (5- 20% by weight), as a chemical blowing agent, was added to the suspension just prior to casting. The suspension was then cast onto a glass surface. Several samples were cast, some containing a blowing agent and some not. The resulting GO films, after removal of liquid, have a thickness that can be varied from approximately 10 to 500 ⁇ .
  • Several sheets of the GO film, with or without a blowing agent were then subjected to heat treatments that involve a heat temperature of 80-500°C for 1-5 hours, which generated a graphene foam structure.
  • interconnected 3D scaffold of nickel was chosen as a template for the growth of graphene foam. Briefly, carbon was introduced into a nickel foam by decomposing CH 4 at 1,000°C under ambient pressure, and graphene films were then deposited on the surface of the nickel foam. Due to the difference in the thermal expansion coefficients between nickel and graphene, ripples and wrinkles were formed on the graphene films. In order to recover (separate) graphene foam, Ni frame must be etched away.
  • PMMA poly(methyl methacrylate)
  • Pitch powder, granules, or pellets are placed in a aluminum mold with the desired final shape of the foam.
  • Mitsubishi ARA-24 meso-phase pitch was utilized. The sample is evacuated
  • a self-assembled graphene hydrogel (SGH) sample was prepared by a one-step hydrothermal method.
  • the SGH can be easily prepared by heating 2 mg/mL of homogeneous graphene oxide (GO) aqueous dispersion sealed in a Teflon- lined autoclave at 180°C for 12 h.
  • the SGH containing about 2.6% (by weight) graphene sheets and 97.4% water has an electrical conductivity of approximately 5 x 10 "3 S/cm.
  • the resulting graphene foam Upon drying and heat treating at 1,500°C, the resulting graphene foam exhibits an electrical conductivity of approximately 1.5 x 10 "1 S/cm, which is 2 times lower than those of the presently invented graphene foams produced by heat treating at the same temperature.
  • FIG.4(A) Shown in FIG.4(A) are the thermal conductivity values vs. specific gravity of the 3D HA- carbon foam, meso-phase pitch-derived graphite foam, and Ni foam template-assisted CVD graphene foam.
  • the 3D integral HA-carbon foams produced by the presently invented process exhibit significantly higher thermal conductivity as compared to both meso-phase pitch-derived graphite foam and Ni foam template-assisted CVD graphene, given the same physical density.
  • CVD graphene is essentially pristine graphene that has never been exposed to oxidation and should have exhibited a high thermal conductivity compared to our HA-carbon hybrid foam.
  • the carbon phase of the hybrid foam is in general of low degree of crystallinity (some being amorphous carbon) and, thus, has much lower thermal or electrical conductivity as compared with graphene alone.
  • the carbon phase is coupled with RHA sheets to form an integral structure produced by the presently invented method, the resulting hybrid foam exhibits a higher thermal conductivity as compared to an all -pristine graphene foam.
  • the specific conductivity of the presently invented hybrid foam materials exhibits values from 250 to 500 W/mK per unit of specific gravity; but those of other types of foam materials are typically lower than 250 W/mK per unit of specific gravity.
  • FIG.4(B) shows the thermal conductivity values of the presently invented hybrid foam and hydrothermally reduced GO graphene foam. Electrical conductivity values of 3D
  • HA-carbon foam and the hydrothermally reduced GO graphene foam are shown in FIG.6. These data further support the notion that, given the same amount of solid material, the presently invented HA-carbon foam is intrinsically most conducting, reflecting the significance of continuity in electron and phonon transport paths. The carbon phase bridges the gaps or interruptions between HA sheets.
  • the internal structures (crystal structure and orientation) of several series of HA-carbon foam materials were investigated using X-ray diffraction.
  • the RHA walls of the hybrid foam materials exhibit a doo 2 spacing typically from 0.3345 nm to 0.40 nm, but more typically up to 0.34 nm.
  • the d 0 o 2 spacing is decreased to approximately to 0.3354 nm, identical to that of a graphite single crystal.
  • the (004) peak intensity relative to the (002) intensity on the same diffraction curve, or the 7(004)//(002) ratio, is a good indication of the degree of crystal perfection and preferred orientation of graphene-like planes.
  • the (004) peak is either non-existing or relatively weak, with the 7(004)//(002) ratio ⁇ 0.1, for all graphitic materials heat treated at a temperature lower than 2,800°C.
  • the 7(004)//(002) ratio for the graphitic materials heat treated at 3,000-3,250°C e.g., highly oriented pyrolytic graphite, HOPG
  • a graphene foam prepared with a final HTT of 2,750°C for one hour exhibits a 7(004)//(002) ratio of 0.78 and a Mosaic spread value of 0.21, indicating the pore walls being a practically perfect graphite single crystal with a good degree of
  • Doc #100005 preferred orientation (if prepared under a compression force).
  • the "mosaic spread” value is obtained from the full width at half maximum of the (002) reflection in an X-ray diffraction intensity curve.
  • This index for the degree of ordering characterizes the graphite or graphene crystal size (or grain size), amounts of grain boundaries and other defects, and the degree of preferred grain orientation.
  • a nearly perfect single crystal of graphite is characterized by having a mosaic spread value of 0.2-0.4.
  • Some of our graphene foams have a mosaic spread value in this range of 0.3-0.6 when produced using a final heat treatment temperature no less than 2,500°C.
  • the presently invented HA-carbon hybrid foam materials typically exhibit significantly higher structural integrity (e.g. compression strength, elasticity, and resiliency) and higher thermal and electrical conductivities as compared to their graphene counterparts produced by the conventional, prior art methods.
  • the presently invented method also allows for convenient and flexible control over the chemical composition (e.g. F, O, and N contents, etc.) of foams, responsive to various application needs (e.g. oil recovery from oil -contaminated water, separation of an organic solvent from water or other solvents, heat dissipation, etc.).
  • chemical composition e.g. F, O, and N contents, etc.
  • foams responsive to various application needs (e.g. oil recovery from oil -contaminated water, separation of an organic solvent from water or other solvents, heat dissipation, etc.).

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  • Carbon And Carbon Compounds (AREA)

Abstract

L'invention concerne une mousse hybride intégrale d'acide humique-carbone 3D composée de pores multiples et de parois poreuses, dans laquelle, les parois poreuses contiennent des feuilles d'acide humique à mono-couche ou à quelques couches liées chimiquement par un matériau carboné à leurs bords et ayant un rapport pondéral entre le matériau de carbone et l'acide humique de 1/200 à 1/2, où les feuilles d'acide humique à quelques couches possèdent de 2 à 10 couches de plans de carbone sensiblement hexagonaux empilés ayant un espace entre plans d?002#191 de 0,3354 nm à 0,40 nm telle que mesurée par diffraction des rayons X et les feuilles d'acide humique mono-couche ou à quelques couches contiennent de 0,01 % à 25 % en poids d'éléments non carbonés, où ledit acide humique étant choisi parmi l'acide humique oxydé, l'acide humique réduit, l'acide humique fluoré, l'acide humique chloré, l'acide humique bromé, l'acide humique iodé, l'acide humique hydrogéné, l'acide humique azoté, l'acide humique dopé, l'acide humique fonctionnalisé chimiquement, ou une combinaison de ceux-ci.
PCT/US2017/043284 2016-08-04 2017-07-21 Mousse hybride intégrale d'acide humique-carbone 3d et dispositifs la contenant WO2018026545A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US15/228,345 2016-08-04
US15/228,133 US11254616B2 (en) 2016-08-04 2016-08-04 Method of producing integral 3D humic acid-carbon hybrid foam
US15/228,133 2016-08-04
US15/228,345 US9878303B1 (en) 2016-08-04 2016-08-04 Integral 3D humic acid-carbon hybrid foam and devices containing same

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WO2018026545A1 true WO2018026545A1 (fr) 2018-02-08

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