Titania−Sepiolite Nanocomposites Prepared by a Surfactant Templating Colloidal Route

Abstract

Microfibrous TiO2−sepiolite and TiO2/SiO2−sepiolite nanocomposites were prepared following a colloidal route based on the controlled hydrolysis of alkoxides in the presence of cetyltrimethylammonium−sepiolite gel. In this way, titanium(IV) isopropoxide and tetramethoxysilane were used as titania and silica precursors, respectively, being incorporated within the organophilic layer developed on the surface of the silicate microfibers and further hydrolyzed in this region. The hydrolysis of the precursor gives highly viscous colloidal systems leading to a spontaneous heterocoagulation process of the colloidal system. Drying and thermal treatments of the resulting gels ensure the elimination of water and organic matter, driving to the formation of TiO2 nanoparticles homogeneously distributed on the surface of the sepiolite microfibers. The nanocomposites were characterized by chemical analyses, transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermogravimetric/differential thermal analysis, and N2 adsorption. They were tested as photocatalysts in the photo-oxidation of phenol in an aqueous medium, showing the efficiency of the anatase containing nanocomposites in the removal of this selected pollutant model molecule. Thiourea was incorporated to increase the TiO2 anatase phase stability, improving in this manner the photocatalytic activity of the TiO2−sepiolite nanocomposites. It has been shown that sepiolite has a positive synergistic effect on the TiO2 photocatalysis.

Porous poly(vinyl alcohol)/sepiolite bone scaffolds: Preparation, structure and mechanical properties

“…It has also been used in conjunction with PVA to form hydrogel fibres where the degree of swelling can be easily controlled by the degree of crosslinking [30]. [30][31][32]. It is composed of blocks, which are characterized by a sandwich structure of a central magnesium octahedral sheet between two silica tetrahedral sheets, forming a capillary network of parallel channels [31][32][33].…”

“…It is composed of blocks, which are characterized by a sandwich structure of a central magnesium octahedral sheet between two silica tetrahedral sheets, forming a capillary network of parallel channels [31][32][33]. Sepiolite features a large specific surface area in the region of 140 -320m 2 /g [31,34], and its interactions with polymer(s) not only take place on the external surface, due to the significant number of silanol (Si-OH) groups but by penetration into the structural channels of sepiolite fibre blocks [35,36]. Previous studies demonstrated good reinforcing capability of sepiolite in polymeric matrices and such reinforcements were obtained at low sepiolite contents, typically lower than 10wt.% [37,38].…”

A comparison between the effects of sepiolite and silica on mechanical properties and thermal stability of NR/EPDM blend

“…To avoid the complications, a silane coupling agent is needed to improve silica-rubber interaction and silica dispersion as well as to prevent accelerator adsorption on the silica surface [5][6][7][8][9]. Sepiolite is a hydrated magnesium silicate clay (Mg2H2SiO3O9.xH2O), Sepiolite has a similar structure to the layered structure of montmorillonite except that the layers lack continuous octahedral sheet [10][11]. The acicular morphology of sepiolite generally improves adhesion/compatibility with polymeric matrices and provides an excellent reinforcing effect on polymer [12] and sepiolite improved the endothermic nature of decomposition reaction.…”

Multifunctional Porous Materials Through Ferrofluids

“…[ 11 ] This behaviour suggests the involvement of these surface groups in the interaction with the magnetite NPs, in a similar way to that observed in anatase NPs anchored on sepiolite surface. [ 12 ] XRD patterns indicate the preservation of magnetite and sepiolite structures ( Figure S2). The widths of the refl ections are compatible with a magnetite NP average size that is in the order of magnitude of 10 nm, in accordance to TEM observations (Figure 1 b).…”