The sorption of propyl and butyl alcohols by silica gel

Abstract

Isothermals of the aliphatic alcohols, from methyl to n -butyl, have been determined on ferric oxide gel, and the isothermals of methyl and ethyl alcohol on two samples of silica gel have also been investigated by the author. One of these silica gels, “gel A,” gave isothermals which were completely reversible, but the other, “ gel B,” showed a small hysteresis loop just before the saturation point was reached. The present paper deals mainly with further experiments on the latter specimen, using normal and iso-propyl alcohols, and normal butyl alcohol. An attempt to determine isothermals of tertiary butyl alcohol was unsuccessful owing to catalytic decomposition of the alcohol in contact with the gel. The same peculiarities which were observed with the lower alcohols have been found to persist throughout the series. The relative pressure at which the hysteresis loop occurs diminishes as the series is ascended, but the capillary radius calculated by means of the Kelvin equation remains constant, as has been found with ferric oxide gel. The data provide important evidence of the validity of this equation for comparative purposes, even when the calculated radii are extremely low.