Adsorption of water and methanol on colloidal iron(III) oxide hydroxides by infrared spectroscopy

Abstract

The surfaces of α-, β- and γ-iron(III) oxide hydroxides have been characterized mainly through the adsorption behaviour of water and methanol by means of F.t.i.r. spectroscopy. In the α-phase two kinds of surface hydroxyl groups with bands at 3485 and 3661 cm^–1 are active for the adsorption of these molecules. In the β-phase two surface hydroxyl groups with bands at 3686 and 3723 cm^–1 are active for the adsorption of both molecules, but that at 3659 cm^–1 is less active. The hydroxyl groups of the γ-phase with a band at 3624 cm^–1 are active for water and methanol adsorption. There seem to be reactive adsorption sites other than surface hydroxyl groups.