title: Adsorption of Uranium over NH2-Functionalized Ordered Silica in Aqueous Solutions.
abstract: The aim of this work was to obtain an in-depth understanding of the U(VI) adsorption mechanism over amino-functionalized mesoporous silica SBA-15 and highlights its high efficiency in aqueous media for U(VI) removal and preconcentration. The samples were synthesized and functionalized by both grafting and co-condensation methods, using different alkyl-substituted amine groups and were characterized using X-ray diffraction, N2physisorption, Fourier transform infrared spectroscopy, and elemental C-H-N-S analyses. The properties for U(VI) adsorption were evaluated under discontinuous conditions, with the determination of the effect of several parameters (initial pH, contact time, initial U(VI) concentration, functionalization method, and organic moiety composition). U(VI) adsorption over grafted materials reached equilibrium at around 30 min, with a maximum adsorption capacity of 573 mgU·gads-1for the most efficient material at its optimal adsorption pH (equal to 6) at 20 °C. Functionalized materials by grafting exhibit better adsorption capacities than co-condensed samples because of higher function surface density and function availability. U(VI) adsorption mechanisms were also studied by measuring the electrophoretic mobilities of the particles, aqueous U(VI) speciation, in situ attenuated total reflection infrared and Raman spectroscopies, and transmission electron microscopy analysis. U(VI) adsorption occurred through the formation of an inner sphere complex. The localization of adsorbed U(VI) has also been determined inside of the mesopores, with the formation of several particles on the nanometer scale, in the size of U-hydroxy phases. Besides, the study of the reusability of amino-functionalized SBA-15 by applying adsorption-desorption cycles was also conducted. The adsorption capacity of the material remains stable for at least four adsorption-desorption cycles without any noticeable capacity decrease.
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Huynh
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Ruben
authors.initials: R
authors.lastname: Palacio
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Fariba
authors.initials: F
authors.lastname: Safizadeh
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris , 11, Rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Lefèvre
authors.affiliation: AREVA-Mining Business Group, Research and Development Department (DR&D) , F-92400 Paris, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Descostes
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Lilian
authors.initials: L
authors.lastname: Eloy
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Nadia
authors.initials: N
authors.lastname: Guignard
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Rousseau
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.|Université Lille, CNRS, ENSCL, Centrale Lille, Université Artois, UMR 8181-UCCS-Unité de Catalyse et de Chimie du, Solide , F-59000 Lille, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Royer
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Tertre
authors.affiliation: Université de Poitiers/CNRS, UMR 7285 IC2MP, Institut de Chimie des Milieux et Matériaux de Poitiers , 5 rue Albert Turpain, 86073 Poitiers, France.
authors.forename: Isabelle
authors.identifier: http://orcid.org/0000-0002-2144-719X
authors.initials: I
authors.lastname: Batonneau-Gener
keywords: adsorption; amine; functionalization; mechanism; mesoporous silica; uranyl