Abstract
An equation for the dissolution of a monodisperse system with an optional initial amount was derived from the Nernst equation. The derived equation was given as a function of the initial amount used for the dissolution test, and was expressed by a form which included the cube root law and negative two-thirds root law equations. Hence, the derived equation is herein abbreviated as the z-law equation following the cube root law and negative two-thirds root law equations. The dissolution measurements of monodisperse crystalline particles using various initial amounts within the amount required to saturate the solution were carried out, and these dissolution processes were treated by use of the z-law equation. The applicability or validity of the z-law equation for the dissolution of monodisperse crystalline particles with optional initial amounts was estimated by a simulation of the dissolution process. As a result, it was suggested that the z-law equation more efficiently explains the dissolution process than the cube root law equation for the treatment of dissolution under sink condition. Also, applicability of the z-law equation was fairly good for dissolution under non-sink condition. Hence, the derived general dissolution equation, i.e., the z-law equation, was thought to be efficient for the treatment of dissolution of a monodisperse system with optional initial amounts within solubility.
