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Comparative study of core-shell nanostructures based on amino-functionalized Fe-4@SiO2 and CoFe2O4@SiO2 nanocomposites

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Arévalo Cid, Pablo and Isasi Marín, Josefa and Martín Hernández, Fátima (2018) Comparative study of core-shell nanostructures based on amino-functionalized Fe-4@SiO2 and CoFe2O4@SiO2 nanocomposites. Journal of alloys and compounds, 766 . pp. 609-618. ISSN 0925-8388

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Official URL: http://dx.doi.org/10.1016/j.jallcom.2018.06.246


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Abstract

Fe3O4@SiO2 and CoFe2O4@SiO2 and their corresponding amino-functionalized nanocomposites were successfully synthesized by a process of two steps including the preparation by coprecipitation or hydrothermal synthesis of the corresponding magnetic cores, the coating of its surface with a silica coating followed by its subsequent functionalization with 3-aminopropyltriethoxysilane (APTES). All magnetic samples were characterized by XRD using FULPROFF program, FTIR analysis, TEM and M-H hysteresis loops. The results showed diffraction maxima indexed in a cubic symmetry of S. G. Fd-3m with Z = 8 compatible with an inverse spinel-type structure. FTIR spectra of all samples show the characteristic bands of the magnetic cores and others bands corresponding to the asymmetric vibration of O-Si-O and Si-O-Si bonds of silica. The TEM images confirm that all the nanoparticles are coated, finding the largest thickness of the coating in the Fe3O4 sample prepared hydrothermally, which are the smaller ones. An expected reduction of the saturation magnetization of the magnetic cores is achieved with the coating and functionalization, although the behaviour of the Fe3O4 -samples remains practically superparamagnetic while the corresponding ones of cobalt are still ferrimagnetic. Fe3O4 nanocomposites respond to more quickly in the presence of an external magnetic field, something important against the removal of contaminating species in aqueous media. UV-Vis spectroscopy studies confirm the adsorption capacity of Cu2+ in aqueous solutions of the prepared nanocomposites, having found that a small thickness of the coating leads a greater adsorption, so that the best adsorption is found for CPFe3O4@SiO2-APTES nanocomposite. (C) 2018 Elsevier B.V. All rights reserved.


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© 2018 Elservier Science
Fundacion Neurociencias y Envejecimiento has supported this work through project 359/2014 as well as MINECO through the project MAT2016-80182-R. The authors thank the ICTS National Center for Electron Microscopy of the UCM for access.

Uncontrolled Keywords:Heavy-metal ions; Coated magnetite nanoparticles; Cobalt ferrite nanoparticles; Cofe2o4 nanoparticles; Organic pollutants; Mesoporous silica; Aqueous-solutions; Drinking-water; Copper removal; Adsorption; Nanocomposites; Magnetic properties; Ferrites; Cations removal
Subjects:Sciences > Physics > Geophysics
Sciences > Physics > Meteorology
ID Code:49748
Deposited On:29 Oct 2018 18:55
Last Modified:14 Nov 2018 12:35

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