A process for the routine determination of the free silanol groups in pyrogenic silicas

摘要

A sample of silicic acid is converted to a clear stable homogenous suspension, using a liquid with a similar refractive index. The IR-spectrum of the silicic acid is taken by a spectral photometer, using a volume of the suspension, which contains a defined amount of silicic acid. The concentratin of the silanol groups is determined from the maximum extinction of the pattern, which is at approx. 3700 cm-1 according to the base line procedure. Exact and fast information about previously difficult to determine free silanol groups is provided.