The Kinetics of Crystallization of Calcium Oxalate Trihydrate

Abstract

The crystal growth of calcium oxalate trihydrate has been studied in supersaturated solutions at 37C under conditions in which the activities of calcium and oxalate ions were maintained constant by the potentiostatically controlled addition of titrant solutions containing these ions. It has been possible to stabilize calcium oxalate trihydrate sufficiently without transformation to the monohydrate, to establish the kinetic behavior. The rate of growth is proportional to the square of the relative supersaturation suggesting a spiral dislocation growth mechanism. Moreover, calcium oxalate trihydrate grows considerably more rapidly than does the monohydrate. Polyphosphate ion inhibits calcium oxalate monohydrate to a much greater extent than trihydrate. In the latter case, the reduction in growth rate in the presence of this ion can be interpreted in terms of a Langmuir isotherm. The stabilization of calcium oxalate trihydrate in the presence of inhibitors by preventing the formation of the transformation product, calcium oxalate monohydrate, may be an important factor in the development of renal stones.

The osteopontin-controlled switching of calcium oxalate monohydrate morphologies in artificial urine provides insights into the formation of papillary kidney stones

“…In case of COT, it is generally accepted that it is the most unstable phase and if it did form would rapidly transform to the monohydrate. Because of this, COT does not usually occur in either urine/urinary stones [52] or in AUs [31]. On the other hand, a study by Opalko et al [45] has shown that AU can crystallize COT besides COM, and that the trihydrate is even stabilized for more than 24 hours when a constant composition or a stirred system was used.…”

Kinetics of crystal growth of calcium sulfate dihydrate. The influence of polymer composition, molecular weight, and solution pH

“…Sheehan and Nancollas (15) have examined the effect of pH in the range 6-9 on the growth rate of C a C 2 0 4 . H 2 0 in the presence of polyacrylate.…”

Calcium oxalates grown in human urine under different batch conditions

“…CaOx formation is further complicated due to the existence of three different hydromorphs. It is believed that COT is the hydromorph most likely to form as an initial crystal nucleus; it is thermodynamically less stable than COM and COD with a lower solubility product [29], which, in accordance with the Otswald-Lussac Law of Stages implies that physically it is the phase most likely to nucleate [50]. As crystallisation progresses and the SS of the system decreases, nucleation of the more stable phases of the CaOx will become favoured as they have a lower solubility.…”