Silica xerogels of tailored porosity as support matrix for optical chemical sensors. Simultaneous effect of pH, ethanol:TEOS and water:TEOS molar ratios, and synthesis temperature on gelation time, and textural and structural properties |
| |
Authors: | Juncal Estella Mariano Laguna |
| |
Affiliation: | a Departamento de Química Aplicada, Universidad Pública de Navarra, Campus Arrosadía, 31006 Pamplona, Spain b Instituto de Ciencia de Materiales de Aragón, CSIC, Universidad de Zaragoza, Campus de Plaza San Francisco, 50009 Zaragoza, Spain |
| |
Abstract: | The sensing of a chemical environment is achieved mainly in the surface by interactions of the sensor material with its chemical surroundings. Therefore, porous structure control is key in developing good chemical sensors. The aim of this work was to obtain materials of tailored porosity to be used as support matrix for optical chemical sensors. We studied the simultaneous effect of pH, temperature, ethanol:TEOS, and water:TEOS molar ratios on gelation time, and textural and structural properties. We used a 24 factorial design that evaluates the effect of each independent variable and their interactions. Samples were characterized by XRD, SEM, FTIR, and gas adsorption (N2 at 77 K and CO2 at 273 K). The gelation time decreased with increasing temperature, water:TEOS molar ratio, and pH; and with decreasing ethanol:TEOS molar ratios. Synthesis conditions also affected the xerogels porous textures. Xerogels obtained at pH 2.5 were ultramicroporous. In general, samples synthesized at pH 4.5 and ethanol:TEOS molar ratio of 2.25:1 were mesoporous, but the material is not appropriate for use as support in fiber optical sensors. |
| |
Keywords: | Sol-gel, aerogel and solution chemistry Sol-gels (xerogels) Adsorption |
本文献已被 ScienceDirect 等数据库收录! |
|