Browsing by Subject "Graphene oxide"

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    Graphene oxide and graphene oxide functionalized with silver nanoparticles as adsorbents of phosphates in waters. A comparative study
    (Elsevier B.V, 2019-12-12) Vicente Martínez, Yésica; Química Analítica
    Phosphate removal is an important factor thatmust be taken into account in eutrophizedwaters. For this reason, many studies on differentways of removing phosphates fromwater have been published nowadays. In thiswork, a comparative study between the use of graphene oxide (GO) and graphene oxide functionalized with silver nanoparticles (GO@AgNPs) as adsorbents to remove phosphates from water samples has been carried out. Experimental conditions, including the pH, adsorbent dose, contact time and temperature, have been analyzed to achieve the highest adsorption efficiency. Although both adsorbents can be considered suitable for removing phosphates from aqueous solutions, GO@AgNPs provided a maximum removal efficiency of 100%, reaching the equilibrium conditions instantaneously under straightforward experimental conditions. Moreover, a much lower adsorbent dose was necessary than with graphene oxide. When GO was used, the maximum removal efficiency was 75%, 9 minwere necessary to reach the equilibriumconditions and 20mgof adsorbentwere needed. Both adsorbents can be regenerated in an acid medium, giving recovery percentages of 98% and 80% for GO and GO@AgNPs respectively, which allows them to be recycled and used again.
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    Ibuprofen Removal by Graphene Oxide and Reduced Graphene Oxide Coated Polysulfone Nanofiltration Membranes
    (MDPI, 2022-05-28) Hidalgo, A.M.; Gómez, M.; Murcia, M.D.; León, G.; Miguel, B.; Gago, I.; Martínez, P.M.; Ingeniería Química
    The presence of pharmaceutical products, and their metabolites, in wastewater has become a focus of growing environmental concern. Among these pharmaceutical products, ibuprofen (IBU) is one of the most consumed non-steroidal anti-inflammatory drugs and it can enter the environment though both human and animal consumption, because it is not entirely absorbed by the body, and the pharmaceutical industry wastewater. Nanofiltration has been described as an attractive process for the treatment of wastewater containing pharmaceutical products. In this paper, the modification of a polysulfone nanofiltration membrane by coating with graphene oxide (GO) and reduced graphene oxide (RGO) has been carried out. The morphology and elemental composition of the active layer of unmodified and modified membranes were analyzed by scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. Initial characterization membranes was carried out, studying their water permeability coefficient and their permeate flux and rejection coefficients, at different applied pressures, using magnesium chloride solutions. The behavior of both pristine and coated membranes against ibuprofen solutions were analyzed by studying the permeate fluxes and the rejection coefficients at different pressures and at different contaminant concentrations. The results have shown that both GO and RGO coated membranes lead to higher values of ibuprofene rejection than that of uncoated membrane, the latter being the one that presents better results in the studies of permeability, selectivity, and fouling.
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    Novel application for graphene oxide-based ionanofluids in flat plate solar thermal collectors
    (Nature Research, 2024-07-30) Moulefera, I.; Pastor, A.R.; Fuster, M.G.; Delgado Marín, J.J.; García Montalbán, Mercedes; Rodríguez Pastor, I.; López Pérez, A.; Martin Gullón, I.; Ramallo González, Alfonso Pablo; Alarcón García, Mariano; Víllora, Gloria; Ingeniería Química
    This study presents new ionanofluids (INF) composed of 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) and graphene oxide (GO) nanoparticles which have been assessed for the first time in an experimental flat plate solar thermal collector (FPSC). For this purpose, four types of INFs were synthesized, maintaining a constant concentration of GO nanoparticles dispersed in different base fluids: ionic liquid (IL/GO), a mixture of ionic liquid and water in varying concentrations (IL-water (75–25)%/GO and IL-water (50–50)%/GO), and water (Water/GO). These four INFs were characterized and their thermophysical and physicochemical properties were determined. The results indicated a 37.4% improvement in efficiency and up to a 2.5-fold increase in temperature within the collector when the IL was applied exclusively as the base fluid, compared to water. Furthermore, IL/GO demonstrated excellent stability, showing no signs of deterioration or nanoparticle precipitation two years after preparation and testing. These findings suggest that INFs based on IL and GO nanoparticles significantly enhance the efficiency of FPSC, presenting a promising option for solar energy applications and opening a new research avenue for INFs in the production of domestic hot water.
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    Ultrafiltration Membranes Modified with Reduced Graphene Oxide: Effect on Methyl Green Removal from Aqueous Solution
    (2023-02-06) Murcia, M.D.; Hidalgo, A.M.; Gómez, M.; León, G.; Gómez, E.; Martínez, M.; Ingeniería Química
    In this work, three types of ultrafiltration membranes with different characteristics (GR60PP, RC70PP and GR80PP) have been tested for the removal of the dye methyl green. The tests were first carried out with the three membranes without any modification and then with the membranes’ surfaces modified with reduced graphene oxide (rGO). The modification was achieved through physical treatment. The CR70PP membrane did not support the modification treatment and was discarded. The other membranes were initially characterized with distilled water tests to study the permeability to the solvent, and later, the permeate fluxes and the values of rejection coefficients were obtained at different working pressures with a fixed dye initial concentration. In addition, SEM images and SEM-EDX spectra of the native and modified membranes were obtained before and after the dye tests. The GR60PP membrane has shown the best results in relation to the modification because it has increased its rejection levels. On the opposite, the GR80PP membrane performs better without surface modification, achieving the highest rejection values and the highest permeate fluxes in its native form. © 2023 by the authors.