PREPARATION OF SOL-GEL SILICA SAMPLES WITH TAILORED PORE STRUCTURES AND EXPRESSIVE ADSORPTION CAPACITIES

Reference	Presenter	Authors (Institution)	Abstract
17-079	Eduardo Henrique Martins NUNES	NUNES, E.H.(UNIVERSIDADE FEDERAL DE MINAS GERAIS); HOUMARD, M.(UNIVERSIDADE FEDERAL DE MINAS GERAIS); Mota, T.(UNIVERSIDADE FEDERAL DE MINAS GERAIS);	This work deals with the preparation of silica samples with both tailored pore structures and adsorption capacities. It was evaluated the capacity of these materials for adsorbing water and methylene blue (MB). On one hand, it is well established that the preparation of porous materials with an expressive water adsorption capacity is crucial for several industrial applications, including gas and food storage, sensing, catalysis, and delivery of drinking water in remote areas. On the other hand, the uptake of organic dyes such as MB represents a promising strategy for mitigating the environmental impacts ascribed to food, paper, paints, and textile industries. The silica sols were prepared using tetraethyl orthosilicate (TEOS), ethanol (EtOH), and hydrochloric acid (HCl) as the silicon precursor, solvent, and catalyst agent, respectively. The molar ratio of TEOS: H2O: EtOH: HCl was adjusted to 1: x: 4: y, where 4 $\le$ x $\le$ 20 and 0 $\le$ y $\le$ 1. Mesoporous materials with ordered pore networks were also obtained using Pluronic® F127 as template. This study is supported by a series of experimental tests, including Fourier transform infrared spectroscopy (FTIR), N2 adsorption, small angle X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was observed that by changing the synthesis conditions it is possible to change both the pore structure and adsorption capacity of sol-gel silica. Samples prepared with no use of template agents showed a promising adsorption capacity, which represents an important advantage in terms of cost and time saving; several works available in the literature deal with complex and multi-step procedures to obtain adsorbents with high adsorption capacities, which makes them cost ineffective and time consuming. Both the kinetics and mechanism of water and MB adsorption by silica was deeply investigated herein.
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