Person:
Calvo Garrido, María Lourdes

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First Name
María Lourdes
Last Name
Calvo Garrido
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
Ingeniería Química
Identifiers
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Now showing 1 - 3 of 3
  • Item
    One-step Sustainable Preparation of Superparamagnetic Iron Oxide Nanoparticles Supported on Mesoporous SiO2
    (Journal of Supercritical Fluids, 2020) Chamorro, Elena; Granados García Tenorio, María José; Calvo Garrido, María Lourdes; Torralvo Fernández, María José; Sáez Puche, Regino; Cabañas Poveda, Albertina
    Superparamagnetic iron oxide nanoparticles (SPIONs) supported on high surface area mesoporous SiO2 are advanced materials of great interest in catalysis, adsorption and biomedicine. Here we present a new process to prepare SPION/SiO2 materials by the impregnation and insitu decomposition of Fe(NO3)3.9H2O on mesoporous SiO2 supports in a 25-50% mol ethanol + CO2 mixture at 523 K and 25.0 MPa. -Fe2O3 nanoparticles (NPs) of average size between 6-9 nm were distributed homogeneously on the supports. NPs deposited into the SBA-15 mesopores but mostly on the external surface of MCM-41. Materials prepared with the highest ethanol content were very homogeneous. Magnetic measurements confirmed the superparamagnetic nature of the materials at room temperature. The process proposed is sustainable and scalable, avoids tedious preparations and the additional high temperature treatment under a controlled atmosphere, as the metal decomposition is performed insitu in the CO2-expanded liquid mixture.
  • Item
    Deposition of Au nanoparticles into mesoporous SiO2 SBA-15
    (The Journal of Supercritical Fluids, 2022) Huerta, Andrea; Torralvo Fernández, María José; Tenorio, María José; Pérez Gómez, Eduardo; Bermúdez, Jonathan; Calvo Garrido, Lourdes; Cabañas Poveda, Albertina; Calvo Garrido, María Lourdes
    Au/SiO2 SBA-15 materials were prepared using supercritical CO2 (scCO2) and by wet impregnation. First, SiO2 SBA-15 was functionalized with thiol groups at different grafting densities using 3-(Mercaptopropyl)trimethoxysilane dissolved in scCO2. The support was then impregnated with HAuCl4·3H2O in scCO2 modified with EtOH. Wet impregnation of the supports with HAuCl4·3H2O in ethanol was also performed. Materials were calcined at 500 ºC to remove the organic matter and promote particle growth. Materials prepared on the highest thiol grafting density support showed Au NP between 2.5-5 nm homogeneously distributed within the mesopores. Slightly larger Au NPs were obtained in scCO2 modified with EtOH. Materials prepared on the low thiol grafting density support showed a bimodal particle size distribution with particles up to 7 nm located inside the mesopores and larger ones of 10-20 nm on the external surface. A possible reaction mechanism was proposed. These materials can be used in catalysis, sensing and biomedicine.
  • Item
    Supercritical fluid impregnation of naproxen into mesoporous SiO2 SBA-15
    (Journal of CO2 utilization, 2023) González, Juan; Pérez Velilla, Eduardo; Pepczynska, Marzena; Calvo Garrido, María Lourdes; Cabañas Poveda, Albertina
    Naproxen was impregnated into mesoporous SiO2 SBA-15 using the Supercritical Solution Impregnation (SSI) technique. Experiments were performed at 50–70ºC and 15–25 MPa in pure CO2 and CO2 modified with ethanol, ethyl acetate and menthol. Materials were also impregnated from liquid solutions in ethanol and chloroform. In the SSI experiments, naproxen was deposited on the internal surface of the mesopores as shown by N2-adsorption experiments. The percentage of naproxen impregnated decreased from 11.1% to 7.4% mass as the CO2 density increased. Likewise, adding ethanol, ethyl acetate or menthol to CO2 decreased the percentage of naproxen adsorbed on the support. Thermal analysis showed that naproxen impregnated on SiO2 by SSI became amorphous. FTIR and XRD confirmed the loss of crystallinity of naproxen and its interaction with the SiO2 support. Samples impregnated in liquid medium however kept partially their crystallinity. Release tests of naproxen on SiO2 SBA-15 prepared by SSI followed an almost zero-order release profile; the drug is released at a constant rate into a PBS pH= 7.4 medium. The release rate slowed down in comparison to that of pure naproxen, due to the interaction of the drug with the support and the diffusion of the drug outside the support mesopores. Thus, a sustained release system was achieved, which may help to attain a longer therapeutic effect with a lower naproxen dose.