title: Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications.
abstract: In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica-organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP) dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica-organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP) homogeneously assembled to the clay-SiO2framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite-silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM). The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain; Laboratory of Physics of Lamellar Materials and Hybrid Nano-Materials (LPLMHNM), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia.
authors.forename: Marwa
authors.initials: M
authors.lastname: Akkari
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Aranda
authors.affiliation: Laboratory of Physics of Lamellar Materials and Hybrid Nano-Materials (LPLMHNM), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia.
authors.forename: Abdessalem
authors.initials: A
authors.lastname: Ben Haj Amara
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, c/ Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ruiz-Hitzky
keywords: ZnO nanoparticles; delamination; montmorillonite; organoclays; photocatalysis; porous clay heterostructures; sepiolite