The kinetics and mechanism of the dehydroxylation of crocidolite

Abstract

This thesis describes the kinetic study of the dehydroxylation of crocidolite. The reaction studied can be represented by the idealized equation: The reaction was studied under vacuum conditions and followed primarily by a weight loss method. The experimental results have been compared with theoretical models for solid state reactions. The results of the dehydroxylation can be explained over the complete reaction range by a diffusion controlled mechanism. It is postulated that oxygen ions are the diffusing species and this postulation agrees with previous x-ray studies and activation energies of diffusion of oxygen in an oxygen lattice. It is shown that the particle controlling diffusion has a radius of less than 30 microns, and it is assumed that these particles are the individual fibres. The enthalpy of activation for the dehydroxylation has been determined, 46 ± 3 k cal./mole., and the entropy of activation is shown to lie in the range 2-6 cal./deg./mole.