Dehydroxylation of crandallite

Abstract

This thesis reports the kinetics and mechanism of the dehydroxylation of crandallite. Studies were made using thermogravimetric, Mössbauer, X-ray and infrared methods. Dehydroxylation is surface nucleated and the subsequent reaction is phase boundary controlled. Dehydroxylation occurs via an inhomogeneous mechanism and the amorphous phase resulting is inhomogeneous. The kinetics of crystallisation of aluminium phosphate from the amorphous phase at higher temperatures are also reported.