Sol-Gel SiO2 Powders Sequestrants of Be2+ in Diluted Solutions

Silica powders of varying morphology were prepared by the sol-gel technique. Typical sol-gel parameters, such as pH of the hydrolysing water solution,H^sub 2^O/Si-OCH^sub 2^CH^sub 3^ molar ratio,thermostatting temperature, and rate of addition of hydrolysingwater, were varied in order to prepare different tailoredsamples, which were then exhaustively hydrolyzed in boilingwater. Samples were characterized by several analyticaltechniques, including surface area and porosity determinations,FT-IR spectroscopy, and thermogravimetric-mass spectrometriccoupled analyses. Samples were used as sequestrants to fixBe^sup 2+^ from diluted water solutions, starting from 5 Beμg L^sup -1^. Their adsorption capabilities werecompared; results were analyzed and discussed taking intoaccount the morphological features of used samples and possible preferential Be^sup 2+^ adsorption by active sites present on the sol-gel SiO^sub 2^ surface.[PUBLICATION ABSTRACT]