Influence of the conditions of preparation on the texture of some silica gels

Silica gels were prepared at pH values varying from 1.5 to 8, and at temperatures of 20 to 90 °C. Specific surface areas were evaluated from the nitrogen adsorption isotherms, employing the BET method, t‐plots, αs‐plots, and Kiselev's integrai equation. Pore‐size distributions as well as cumulative surface areas were determined by the procedure of Cranston and Inkley. An increase in pH causes a decrease in the specific area, and an increase in both the mean pore radius and pore volume of the xerogel. An increase in the BET'S C value appeared with an increase in the mean pore radius and the number of OH‐groups (NOH) of the material.