THE KINETICS OF DISSOLUTION OF CALCIUM-OXALATE HYDRATES .2. THE DIHYDRATE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 18  (2) , 97-101
Abstract
The kinetics of calcium oxalate dehydrate (COD) dissolution were studied over a range of temperature and ionic strength. The rate of dissolution is proportional to the relative undersaturation expressed in terms of ionic activities. Subsequent transformation to the thermodynamically more stable monohydrate (COM) takes place by a secondary nucleation process. This transformation is dependent upon the COD specific surface area, and is appreciably slower than for the corresponding trihydrate transformation of comparable area. In the presence of polyphosphate, which retards the transformation COD .fwdarw. COM, the dissolution of COD seems to be controlled by a surface reaction. Differences in dissolution rates and adsorption behavior among the 3 calcium oxalate hydrates may play a part in determining the nature of the mineral phases that form in vivo.