FORMATION OF OTAVITE BY SUBSTITUTION OF ORGANIGENIC LIMESTONE

摘要

Rare Cd carbonate-otavite-has been obtained in the experimental system by interaction of cadmium-bearing solutions with the contemporary organiogenic shelly limestone. Specifications of the experiment corresponded to conditions of the technogenic pollution of the sea bottom sediments. Substitution of the limestone by otavite carries itself out, under the normal temperature, steadily, but the principal amount of the Cd mass become absorbed by the shelly limestone during the initial three-four days. The desorption of Cd by the sea water, as a process, practically has not place. The newly formed otavite envelopes the calcite graines, as well as developes along fissures and, particularly, in micropores. There is a revealed dependence between the degree of substitution (limestone by otavite) and textural-structural peculiarities of the substituted shell detritus. The mere forming of otavite has been confirmed by the X-ray diffraction study. Besides the otavite itself, as the microprobe analysis has shown, mixed calcite-otavite crystals were formed also. The isomorphous substitution of Ca by Cd in organogenic limestone allow to recommend this rock as a sorbent of cadmium from water polluted by industrial swages.