Titania deposits on nanosilicas

Abstract

Titania (content C TiO2 = 2.7-20.0 wt%) was synthesized on different fumed silica substrates (A-50, A-100, A-380) using Ti[OCH(CH 3 ) 2 ] 4 as a precursor interacting with silica/adsorbed water in 2-propanol or CCl 4 medium, dried and then heated at 1073 K for 1 h. Initial and pretreated nanosilicas and titania/silicas were studied using XRD, adsorption, FTIR, TEM, AFM, and TPD-MS methods. The morphology of grafted titania (anatase/rutile/amorphous phase composition, particle size distribution, aggregation, textural porosity) depends on the types of a nanosilica matrix and a solvent, suspension treatments and reaction conditions.

Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions

“…The ATR-FTIR spectra are consistent with the XRD and TEM results [ 40 ] revealing that the particulate morphology of titania correspond to crystalline anatase. In the case of ST20, the titania particles ranged between 15 and 20 nm.…”

“…It was found that titania grafted onto silica A-50 is characterized by much lower crystallinity than titania synthesized alone because of silica inhibitory effects [ 40 ]. Modification of ST20 by sodium alginate can change diffusion of adsorbate into pores (voids) and provide a possibility for further surface modification.…”

Morphological and Electronic Characteristics of Nanoalumina Alone and in High-Temperature (Fumed) and Low-Temperature (Mechanical) Mixtures with Nanosilica

“…The total pore volume V p was evaluated from the nitrogen adsorption at p/p 0 = 0.98-0.99 (p and p 0 denote the equilibrium pressure and the saturation pressure of nitrogen at 77.4 K, respectively). The nitrogen desorption data [25] were used to compute pore size distributions (PSDs) (differential f V (R p ) ~ d V p /dR p and f S (R p ) ~ dS/dR p ) using a regularization procedure [26] under non-negativity condition (f V (R p ) 0 at any R p ), at a fixed regularization parameter = 0.01, with a model of voids between spherical nanoparticles packed in random aggregates (V model) with a self-consistent regularization (SCR) procedure [27,28]. The differential distribution functions f V (R p ) ( f V (R p )dR p ~ V p ) were converted to incremental PSD (IPSD, (R p ) at i (R p ) ~ V p ).…”