Kinetics of Precipitation and Cryst~l Growth of Dicalcium Phosphate Dihydrate

The kinetics of the precipitation and crystal growth of dicalcium phosphate dihydrate (DCPD) was followed in 0.15 M sodium chloride solutions at constant pH (pH = 5.0) and temperature (25o C). Precipitations were performed from equimolar solutions of calcium chloride and sodium phosphate prepared by direct mixing of the reactants. The amount of precipitate formed (X moles per 1) was calculated from the quantity of sodium hydroxide added by a pH-stat device. The system is of physiological interest, because precipitation of DCPD may play an important role during dental caries formatio

Kinetics of Precipitation and Cryst~l Growth of Dicalcium Phosphate Dihydrate

The kinetics of the precipitation and crystal growth of dicalcium phosphate dihydrate (DCPD) was followed in 0.15 M sodium chloride solutions at constant pH (pH = 5.0) and temperature (25o C). Precipitations were performed from equimolar solutions of calcium chloride and sodium phosphate prepared by direct mixing of the reactants. The amount of precipitate formed (X moles per 1) was calculated from the quantity of sodium hydroxide added by a pH-stat device. The system is of physiological interest, because precipitation of DCPD may play an important role during dental caries formatio

An Apparatus for Synchronized Precipitation under Sterile Conditions

The apparatus for .synchronized precipitation devised earlier1 enables the experimenter to achieve extremely slow and controlled mixing of the reactants and to avoid local supersaturations

Nucleation of Calcium Phosphate from Solutions at Physiological pH

In a previous paper1 it was shown that when phase transition from aqueous solutions occurs at metastable equilibrium, the stoichiometry of the nucleating phase can be conveniently evaluated from the precipitation boundary2 • The method was applied to calcium phosphates nucleating in the pH range 6.3 , to 9.1 from solutions containing calcium chloride and sodium phosphate at constant total phosphate concentration 1 X 10-3 M. The calcium phosphate ratio of the nucleating phase was found to be 1.5 and the formation of an amorphous metastable precursor to hydroxyap atite was concluded. Because of its implications on biological calcification it was of interest to reexamine this result restricting the experiments to the physiological pH region (pH 7.25-7.5), but taking into account possible variations of total phosphate and total calcium concentrations. This was done as part of more extensive investigations of the precipitation of calcium phosphates from aqu eous solutions and from media containing 0.15 M sodium chlorid e