7.1 Incentivos para publicaciones indizadas

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https://hdl.handle.net/20.500.12390/386

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Examinando 7.1 Incentivos para publicaciones indizadas por Tema "Adsorption"
  • Publicación
    Adsorption of arsenite and arsenate on binary and ternary magnetic nanocomposites with high iron oxide content
    (Elsevier, 2018)
    Ramos Guivar J.A.
    ;
    Bustamante D. A.
    ;
    Gonzalez J.C.
    ;
    Sanches E.A.
    ;
    Morales M.A.
    ;
    Raez J.M.
    ;
    López-Muñoz M.-J.
    ;
    Arencibia A.
    Bare maghemite nanoparticles (Nps), binary, and ternary magnetic nanocomposites made with titanium dioxide (TiO2) and graphene oxide (GO) were synthesized by a facile and cheap coprecipitation chemical route, and used as magnetic nanoadsorbents to remove arsenite (As(III)) and arsenate (As(V)) from water. The structural, morphological, magnetic and surface properties were analyzed by XRD, TEM microscopy, FTIR and Raman vibrational spectroscopy, Mössbauer technique and N2 adsorption-desorption measurements. It was found that materials were composed of maghemite nanoparticles with crystallites diameters varying from 9 to 13 nm for bare Nps, binary and ternary nanocomposites, with these nanocomposites having a high percentage of maghemite phase (80%). The presence of TiO2 and GO in the binary and ternary materials was also confirmed. All the samples were found to show magnetic properties and a slight porosity, with a specific surface area that increases up to 82 m2 /g when the metal oxides Nps were supported on GO. The aqueous arsenic adsorption performance was studied from kinetic and equilibrium point of view, and the pH adsorption capacity dependence was evaluated aiming to explain the adsorption mechanism. The three nanocomposites prepared in this work exhibit high adsorption capacity for arsenic species, with values of maximum adsorption capacity ranging from 83.1 to 110.4 mg/g for As(III) and from 90.2 to 127.2 mg/g for As(V) from bare to ternary nanocomposites, and can be fast separated with a permanent magnet of neodymium (Nd) in less than 10 min. Therefore, these nanosystems can be proposed as good adsorbents for both arsenic species from water.
  • Publicación
    Magnetic, structural and surface properties of functionalized maghemite nanoparticles for copper and lead adsorption
    (Royal Society of Chemistry, 2017)
    Guivar, JAR
    ;
    Sadrollahi, E
    ;
    Menzel, D
    ;
    Fernandes, EGR
    ;
    Loez, EO
    ;
    Torres, MM
    ;
    Arsuaga, JM
    ;
    Arencibia, A
    ;
    Litterst, FJ
    In this study, magnetic nanocomposites were developed and used as adsorbents for lead and copper from aqueous media. Structural, surface, magnetic and textural properties of functionalized maghemite nanoparticles synthesized by alkaline co-precipitation were studied. The surfaces of the iron oxide nanoparticles (Nps) were modified with different chemical agents such as fatty and amino acids, silica (SiO2), mesoporous silica (SBA-15), hydroxyapatite, multiwall carbon nanotubes (MWCNTs) and ethylenediaminetetraacetic acid (EDTA), obtaining NPs with mean particle sizes ranging from 7 to 16 nm according to Rietveld refinement and TEM images analysis. The physicochemical surface properties of the functionalized materials were studied via zeta potential (z) and Fourier transform infrared (FTIR) spectroscopy. Mossbauer spectroscopy (MS) as a function of temperature and DC magnetometry were ¨ used to study the magnetic properties. The superparamagnetic relaxation was studied by MS. The resolved spectra at 20 K confirm the presence of nanomaghemite phase. Besides, the saturation magnetization varies from 12 to 62 emu g 1 . A nitrogen adsorption–desorption technique was used to determine the specific surface area and to study the porous structure. The functionalized g-Fe2O3 Nps exhibited a Brunauer–Emmett–Teller (BET) specific surface area ranging from 74 to 214 m2 g 1 and revealed remarkable uptake capacities to remove Cu(II) and Pb(II) species from aqueous solutions