Abstract
Abstract Dehydration of colloidal silicas by heating at elevated temperatures improves their ice nucleating ability. Adsorption studies were performed to study their surface characteristics, on both hydroxylated and dehydroxylated samples. To monitor surface areas, argon was found to be a more reliable adsorbent than nitrogen. The latter displayed a specificity depending on hydroxyl concentration. The highly dehydrated amorphous silicas gave the same surface areas if 16.2 A2 was used for the co-area of nitrogen and 16.6 A2 for argon. Water adsorption was used to assess the surface concentration of hydroxyls and isopropanol adsorption to determine their steric distribution. The dehydrated silica prepared by heating a wet, precipitated variety hydrated partially on cooling in air. Contrary to earlier reports, boiling in water did not yield a fully hydroxylated surface.
Published Version
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