title: The crystallization of calcium carbonate on sodium cholate.
abstract: Recent studies in the bibliography showed that calcium carbonate was the major constituent (77.8%) in gall stones, and the polymorph calcite was at 62.5% of the cases examined. The kinetics of crystallization of calcite on sodium cholate has been studied using the constant composition technique. Analysis of the initial rates as a function of the solution supersaturation, according to the classical nucleation theory, yielded a value of 33mJm(-2) for the surface energy of the growing phase and a five-ion cluster, forming the critical nucleus. The apparent order for the calcite crystallization was found to be 4.5+/-0.7 indicative of a surface nucleation mechanism. The formation of calcite may be initiated through the interaction of Ca2+ ions with the negative end of the C=0 bond of the sodium cholate molecule.
authors.affiliation: Department of Chemistry, University of Patras, GR-26500 Patras, Greece.
authors.forename: F
authors.initials: F
authors.lastname: Manoli
authors.forename: E
authors.initials: E
authors.lastname: Dalas