Acidity of Alginate Aerogels Studied by FTIR Spectroscopy of Probe Molecules

Supercritical drying of alginate gels is an efficient way to prepare aerogels with high surface area (>300 m2 · g−1). FTIR spectroscopy allows to monitor the adsorption of NH3 from the gas phase onto the acid sites of the alginate. Free carboxylic groups are effective Brønsted sites, whereas the...

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Bibliographic Details
Published in:Macromolecular symposia 2005-12, Vol.230 (1), p.71-77
Main Authors: Valentin, Romain, Horga, Raluca, Bonelli, Barbara, Garrone, Edoardo, Di Renzo, Francesco, Quignard, Françoise
Format: Article
Language:English
Subjects:
aerogel
Aerogels
alginate
Alginates
ammonia adsorption
Applied sciences
Drying
Exact sciences and technology
FTIR spectroscopy
Gelation
Monitors
Natural polymers
Physicochemistry of polymers
Spectroscopy
Starch and polysaccharides
supercritical drying
Surface area
Surface chemistry
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Summary:Supercritical drying of alginate gels is an efficient way to prepare aerogels with high surface area (>300 m2 · g−1). FTIR spectroscopy allows to monitor the adsorption of NH3 from the gas phase onto the acid sites of the alginate. Free carboxylic groups are effective Brønsted sites, whereas the divalent cations used in the ionotropic gelation present the properties of Lewis sites. The ratio between Brønsted and Lewis sites provides infomation on the role of pH in alginate gelation and suggests that non‐buffered gelation by transition‐metal cations is a mixed ionotropic‐acid process.
ISSN:1022-1360
1521-3900
DOI:10.1002/masy.200551144