Browsing by Keyword "Graphene"
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Item Electro-spun graphene-enriched carbon fibres with high nitrogen-contents for electrochemical water desalination(2018-02-15) Belaustegui, Yolanda; Zorita, Saioa; Fernández-Carretero, Francisco; García-Luis, Alberto; Pantò, Fabiola; Stelitano, Sara; Frontera, Patrizia; Antonucci, Pierluigi; Santangelo, Saveria; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; ADAPTACIÓN AL CAMBIO CLIMÁTICO; TECNOLOGÍAS DE HIDRÓGENOElectro-spun carbon fibres doped with very high nitrogen concentrations (19–21 wt%) are obtained operating carbonisation at low temperature (500 °C). The as-synthesised fibres are evaluated as electrode materials for the electrochemical desalination of water. The effect of the enrichment of the nitrogen doped carbon fibres with thermally reduced graphene oxide is also investigated. The fibrous electrodes are able to remove amazing amounts of NaCl (17.0–27.6 mg/g) from a salty solution with an initial concentration of 585 mg/L. The nitrogen doping, which dramatically improves the wettability, plays a crucial role in determining the outstanding electro-sorption capacities of the fibres. It allows fully profiting of the more favourable pore size distribution in the graphene-enriched fibres, endowed with higher conductivity and capacitance, for the obtainment of unprecedented electro-sorption capacities via an extremely simple synthesis process, with no need of activation treatments.Item Exposure to graphene in a pilot production plant(2019-10-17) Vaquero, C.; Wendelbo, R.; Egizabal, A.; Gutierrez-Cañas, C.; López de Ipiña, J.; PRINTEX; Biomateriales; SMART_MONWorkers exposure to graphene was measured in a pilot production plant. Reduced graphene oxide was produced through graphite oxidation and posterior thermal reduction. The monitoring was performed using two handheld on-line devices covering the particle size range from 10 nm to 10 μm (CPC3007 and OPS3330). Simultaneously, personal and area filter samples were collected for off line analysis, including gravimetric, elemental carbon analysis and SEM/EDX. Significant releases of particles were identified in two tasks, during the graphene oxide washing, and during its milling. However, the analysis of the particles size distribution and of their morphology suggested that the released particles were not the target nanomaterial but engine generated nanoparticles. The mass of elemental carbon in the collected filters was below the quantification limit and the calculated graphene mass concentrations were quite below the selected reference exposure limit. Overall, this work showed that worker exposure to graphene was low in this pilot plant, contributing to guarantee a safe process, prior to its industrialization.Item Growth of nano-textured graphene coatings across highly porous stainless steel supports towards corrosion resistant coatings(2015-02-01) Dumée, Ludovic F.; He, Li; Wang, Ziyu; Sheath, Phillip; Xiong, Jianyu; Feng, Chunfang; Tan, Mike Yongjun; She, Fenghua; Duke, Mikel; Gray, Stephen; Pacheco, Alfredo; Hodgson, Peter; Majumder, Mainak; Kong, Lingxue; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn this paper, we demonstrated for the first time the growth of 3D networks of graphene nano-flakes across porous stainless steel substrates of micron sized metal fibres, and its anti-corrosion properties. The controlled formation of graphene-grade coatings in the form of single sheets to complex and homogeneously distributed 2-4 μm long nano-pillars is demonstrated by Scanning Electron Microscopy. The morphology and stability of these structures are shown to be particularly related to the temperature and feed gas flow rate during the growth. The number of layers across the graphene materials was calculated from the Raman spectra and is shown to range between 3 and more than 15 depending on the growth conditions and to be particularly related to the time and flow rate of the experiment. The presence of the graphene was shown to massively enhance the specific surface area of the material and to contribute to the increased corrosion resistance and electrical conductivity of the material without compromising the properties or structure of the native stainless steel materials. This new approach opens up a new route to the facile fabrication of advanced surface coatings with potential applications in developing new thermal exchangers, separation and bio-compatible materials.Item Hollow fiber membranes of PCL and PCL/graphene as scaffolds with potential to develop in vitro blood– brain barrier models(2020-08) Mantecón-Oria, Marián; Diban, Nazely; Berciano, Maria T.; Rivero, Maria J.; David, Oana; Lafarga, Miguel; Tapia, Olga; Urtiaga, Ane; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThere is a huge interest in developing novel hollow fiber (HF) membranes able to modulate neural differentiation to produce in vitro blood–brain barrier (BBB) models for biomedical and pharmaceutical research, due to the low cell-inductive properties of the polymer HFs used in current BBB models. In this work, poly(ε-caprolactone) (PCL) and composite PCL/graphene (PCL/G) HF membranes were prepared by phase inversion and were characterized in terms of mechanical, electrical, morphological, chemical, and mass transport properties. The presence of graphene in PCL/G membranes enlarged the pore size and the water flux and presented significantly higher electrical conductivity than PCL HFs. A biocompatibility assay showed that PCL/G HFs significantly increased C6 cells adhesion and differentiation towards astrocytes, which may be attributed to their higher electrical conductivity in comparison to PCL HFs. On the other hand, PCL/G membranes produced a cytotoxic effect on the endothelial cell line HUVEC presumably related with a higher production of intracellular reactive oxygen species induced by the nanomaterial in this particular cell line. These results prove the potential of PCL HF membranes to grow endothelial cells and PCL/G HF membranes to differentiate astrocytes, the two characteristic cell types that could develop in vitro BBB models in future 3D co-culture systems.Item Three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles as efficient active material for high performance capacitive deionization electrodes(2021-05-15) Belaustegui, Yolanda; Rincón, Inés; Fernández-Carretero, Francisco; Azpiroz, Patxi; García-Luís, Alberto; Tanaka, David Alfredo Pacheco; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles (3D rGO-Fe2O3) material with a suitable porous structure was synthesised using a one-step hydrothermal process in order to fabricate novel electrodes for capacitive deionization (CDI) water desalination. The morphological and structural properties of the as-synthesised compounds were characterised by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Raman spectroscopy (RS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The CDI electrodes were electrochemically analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A maximum value of specific capacitance of 345 F g−1 was achieved at 5 mV s−1 scan rate using a NaCl 0.1 mol L−1 solution. The ion removal performance of the CDI electrodes was evaluated with NaCl solutions of different concentrations, showing electrosorption capacities as high as 945 mg g−1 for 11,700 mg L−1 (200 mmol L−1) NaCl solutions, which substantially surpasses results of other carbon-based CDI electrodes.