Infrared study of surface hydroxyl groups on goethite

Abstract

Infrared spectra of goethite (α-FeOOH) exhibited bands which have been assigned to OH stretching vibrations of bulk or surface hydroxyl groups. On exposure of goethite to deuterium oxide vapour the latter underwent rapid isotopic exchange to give the corresponding surface deuteroxyl groups. The conversion of bulk hydroxyl groups to bulk deuteroxyl groups by contact between deuterium oxide vapour and goethite was comparatively slow. Analogous conclusions were drawn from spectra of deuterated goethite (α-FeOOD) before and after treatment with water vapour. The decomposition of geothite to haematite (α-Fe₂O₃) by heat treatment in vacuo or in an oxygen atmosphere has been briefly investigated.