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Enhanced Reduction of Few-Layer Graphene Oxide via Supercritical Water Gasification of Glycerol.

ABSTRACT: A sustainable and effective method for de-oxygenation of few-layer graphene oxide (FLGO) by glycerol gasification in supercritical water (SCW) is described. In this manner, reduction of FLGO and valorization of glycerol, in turn catalyzed by FLGO, are achieved simultaneously. The addition of glycerol enhanced FLGO oxygen removal by up to 59% due to the in situ hydrogen generation as compared to the use of SCW only. Physicochemical characterization of the reduced FLGO (rFLGO) showed a high restoration of the sp²-conjugated carbon network. FLGO sheets with a starting C/O ratio of 2.5 are reduced by SCW gasification of glycerol to rFLGO with a C/O ratio of 28.2, above those reported for hydrazine-based methods. Additionally, simultaneous glycerol gasification resulted in the concurrent production of H₂, CO, CH₄ and valuable hydrocarbons such as alkylated and non-alkylated long chain hydrocarbon (C12-C31), polycyclic aromatic hydrocarbons (PAH), and phthalate, phenol, cresol and furan based compounds.

SUBMITTER: Torres D

PROVIDER: S-EPMC5746937 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Biohydrogen Production by Catalytic Supercritical Water Gasification: A Comparative Study.

Project description:In this article, supercritical water gasification of biocrude at different conditions was performed and compared to each other. Three scenarios were considered while treating biocrude originating from cattle manure (CM) and corn husk (CH), namely, uncatalyzed feedstock, catalyzed with 10% Ni-0.08% Ru/Al2O3 and finally catalyzed with 10% Ni-0.08% Ru/Al2O3-ZrO2. It was found that 10% Ni-0.08% Ru/Al2O3-ZrO2 has performed significantly better than the other two scenarios over the 5 hour run time with a 193 and 187% higher hydrogen yield compared to the uncatalyzed and 10% Ni-0.08% Ru/Al2O3 catalyzed scenarios, respectively. Compared to CM gasification in the presence of a 10% Ni-0.08% Ru/Al2O3-ZrO2 catalyst, the catalyst got deactivated because of the high phenol and furan content in the corn husk biocrude, therefore hydrogen yield performance fell significantly. It was observed that the carbon gasification efficiency of the biocrude was independent of temperature. In terms of carbon conversion, the equilibrium conditions for the biocrude considered were attained at lower temperature. A mechanistic model based on the Eley-Rideal method was devised and tested against the obtained data. The dissociation of adsorbed oxygenated hydrocarbon is found to be the rate-determining step with an average absolute deviation of 3.55%.

| S-EPMC7331078 | biostudies-literature

One-Step Green Hydrothermal Synthesis of Few-Layer Graphene Oxide from Humic Acid.

Project description:The conventional synthesis route of graphene oxide (GOG), based on Hummers method, suffers from explosion risk, environmental concerns and a tedious synthesis process, which increases production costs and hinders its practical applications. Herein, we report a novel strategy for preparing few-layer graphene oxide (GOH) from humic acid via simple hydrothermal treatment. The formation of GOH is mainly attributed to the hydrolysis, oxidation and aromatization of humic acid under hydrothermal conditions. The as-prepared few-layer GOH has typical morphology (thin and crumpled sheets with the thickness of ~3.2 nm), crystal structure (a Raman ID/IG ratio of 1.09) and chemical composition (an X-ray Photoelectron Spectroscopy (XPS) O/C atomic ratio of 0.36) of few-layer GOG. The thermally reduced GOH (r-GOH) delivers considerable area capacitance of 28 µF·cm-2, high rate capability and low electrochemical resistance as supercapacitor electrodes. The described hydrothermal process shows great promise for the cheap, green and efficient synthesis of few-layer graphene oxide for advanced applications.

| S-EPMC5923545 | biostudies-literature

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| S-EPMC8591986 | biostudies-literature

Water Dispersible Few-Layer Graphene Stabilized by a Novel Pyrene Derivative at Micromolar Concentration.

Project description:The search for graphene or few-layer graphene production methods that are simple, allow mass production, and yield good quality material continues to provoke intense investigation. The present work contributes to this investigation through the study of the aqueous exfoliation of four types of graphene sources, which are namely graphite and graphite nanoflakes with different morphologies and geographical origins. The exfoliation was achieved in an aqueous solution of a soluble pyrene derivative that was synthesized to achieve maximum interaction with the graphene surface at low concentration (5 × 10-5 M). The yield of bilayer and few-layer graphene obtained was quantified by Raman spectroscopic analysis, and the adsorption of the pyrene derivative on the graphene surface was studied by thermogravimetric analysis and X-ray diffraction. The whole procedure was rationalized with the help of molecular modeling.

| S-EPMC6163987 | biostudies-literature

Layer-by-Layer Insight into Electrostatic Charge Distribution of Few-Layer Graphene.

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| S-EPMC5318858 | biostudies-literature

Interfacial Atomic Structure of Twisted Few-Layer Graphene.

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| S-EPMC4758067 | biostudies-literature

Flake electrical conductivity of few-layer graphene.

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UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration.

Project description:Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200?hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8?L m(-2) h(-1) bar(-1) for water, and 0.14 to 7.5?L m(-2) h(-1) bar(-1) for acetone, with an unchanged low molecular weight cut off (~250?Da).

| S-EPMC4630626 | biostudies-literature

Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide.

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| S-EPMC8151798 | biostudies-literature

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