Abstract
The rates of chemical dissolution of spherical gypsum were measured in aqueous solutions of several kinds of chelating agents, such as EDTA, CyDTA, DTPA, GEDTA, and EDTA-OH. Particularly in EDTA solution, the relation between the power of ultrasound and the rate of chemical dissolution accelerated by ultrasonic irradiation was investigated in details. The investigation has revealed that the mechanism of the chemical dissolution of the gypsum and how ultrasound acts on the acceleration of the dissolution. These dissolution mechanisms are also applied to the chelating agents other than EDTA. Considering also the chemical properties of the agents, it has been deduced that the rate of chemical dissolution of calcium salt in crystal state seemed to be dependent on the concentration of chelating agent ions, i.e. ligands, having more than four uncoordinated donor groups and the values of the effective stability constant.
