title: Tailoring bifunctional hybrid organic-inorganic nanoadsorbents by the choice of functional layer composition probed by adsorption of Cu2+ions.
abstract: Spherical silica particles with bifunctional (≡Si(CH2)3NH2/≡SiCH3, ≡Si(CH2)3NH2/≡Si(CH2)2(CF2)5CF3) surface layers were produced by a one-step approach using a modified Stöber method in three-component alkoxysilane systems, resulting in greatly increased contents of functional components. The content of functional groups and thermal stability of the surface layers were analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and13C and29Si solid-state NMR spectroscopy revealing their composition and organization. The fine chemical structure of the surface in the produced hybrid adsorbent particles and the ligand distribution were further investigated by electron paramagnetic resonance (EPR) and electron spectroscopy of diffuse reflectance (ESDR) spectroscopy using Cu2+ion coordination as a probe. The composition and structure of the emerging surface complexes were determined and used to provide an insight into the molecular structure of the surfaces. It was demonstrated that the introduction of short hydrophobic (methyl) groups improves the kinetic characteristics of the samples during the sorption of copper(II) ions and promotes fixation of aminopropyl groups on the surface of silica microspheres. The introduction of long hydrophobic (perfluoroctyl) groups changes the nature of the surface, where they are arranged in alternately hydrophobic/hydrophilic patches. This makes the aminopropyl groups huddled and less active in the sorption of metal cations. The size and aggregation/morphology of obtained particles was optimized controlling the synthesis conditions, such as concentrations of reactants, basicity of the medium, and the process temperature.
authors.affiliation: Chuiko Institute of Surface Chemistry of NASU, 17, Generala Naumova Str., Kyiv 03164, Ukraine.
authors.forename: Veronika V
authors.initials: VV
authors.lastname: Tomina
authors.affiliation: Chuiko Institute of Surface Chemistry of NASU, 17, Generala Naumova Str., Kyiv 03164, Ukraine; Institute of Geotechnics SAS, 45, Watsonova, Kosice 04001, Slovak Republic.
authors.forename: Inna V
authors.initials: IV
authors.lastname: Melnyk
authors.affiliation: Chuiko Institute of Surface Chemistry of NASU, 17, Generala Naumova Str., Kyiv 03164, Ukraine.
authors.forename: Yuriy L
authors.initials: YL
authors.lastname: Zub
authors.affiliation: Department of Inorganic Chemistry, Vilnius University, 24, Naugarduko Str., Vilnius LT-03225, Lithuania.
authors.forename: Aivaras
authors.initials: A
authors.lastname: Kareiva
authors.affiliation: Institute of Geotechnics SAS, 45, Watsonova, Kosice 04001, Slovak Republic.
authors.forename: Miroslava
authors.initials: M
authors.lastname: Vaclavikova
authors.affiliation: Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, 8, Almas allé, Uppsala 75007, Sweden.
authors.forename: Gulaim A
authors.initials: GA
authors.lastname: Seisenbaeva
authors.affiliation: Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, 8, Almas allé, Uppsala 75007, Sweden.
authors.forename: Vadim G
authors.initials: VG
authors.lastname: Kessler
keywords: N- and F-containing functional groups; copper(II) ions; methyl groups; silica nanospheres; sol–gel processes; sorption; surface chemistry