Browsing by Subject "Reduced graphene oxide"

Now showing 1 - 5 of 5
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    Comparison of sulfamethoxazole removal efficiency using polyethersulfone ultrafiltration membrane modified by various methods
    (MDPI, 2024-12-20) Hidalgo, Asunción María ; Murcia, María Dolores; Gómez, María ; Collado-González, Mar ; Montiel, María Claudia ; Martínez, Marta; Ingeniería Química ; Biología Celular e Histología
    Nowadays, there is a growing interest in membrane modification processes to improve their characteristics and the effectiveness of their treatments and reduce the possible fouling. In this sense, in this work, a modification of an ultrafiltration membrane with three different materials has been carried out: reduced graphene oxide (rGO), chitosan and MgCl2. For both the native and the modified membranes, a study has been carried out to remove the emerging contaminant sulfamethoxazole (SMX). SEM and SEM-EDX analyses have been performed to confirm membrane surface modifications. In the characterisation of the membranes, it is noteworthy that the values of the permeability coefficient, Aw, have been lower in the modified membranes, which is unexpected. Regarding the pollutant removal tests, the influence of pressure and initial concentration on permeate flux and rejections has been studied. Native membrane shows the highest permeate flux values. Comparing the modified membranes, the highest rejection values are obtained with the rGO-modified membrane, which can be explained by its greater hydrophilic character. Finally, a fouling study was carried out, verifying that in almost all cases, fouling occurs after the passage of the pollutant due to the blockage of the membrane pores.
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    Exploring the structure andelectronic properties of individual hybrid GO/rGOflakes
    Navarro-Rodriguez, Mario; Camus, Victor; Cros, Ana; Garro, Nuria; Somoza, Andres M.; Palacios-Lidon, Elisa; Física
    Despite its great potential, the use of graphene oxide (GO) in sensors, photocatalysis, or biomedicine applications is limited by its low conductivity. This drawback is typically overcome by using its reduced form (rGO) albeit sacrificing some of its extensive chemical properties. In this study, we unveil a nonuniform reduction process that enables the fabrication of hybrid flakes consisting of both size tunable GO and rGO regions. The nanoscale resolution of Kelvin probe force microscopy together with co-localized Raman spectroscopy allow us to correlate the local reduction degree with the nanoscale electronic properties, chemical composition, and structural defects. Additionally, we introduce a reliable metric for quantifying the extent of reduction. This research opens up possibilities for the development of new 2D nanohybrid materials that combine the high reactivity of GO and the enhanced conductivity of rGO, enabling applications in selective functionalization.
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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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    Ibuprofen Removal by Graphene Oxide and Reduced Graphene Oxide Coated Polysulfone Nanofiltration Membranes
    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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    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.