Comminution of pharmaceutical substances by the adiabatic expansion of supercritical fluid solutions

Abstract

The adiabatic expansion of supercritical fluid solutions and solubility in pharmaceutical substance–carbon dioxide systems have been investigated. The solubility and average particle size of pharmaceutical substances depend on thermodynamic and geometric parameters of the process. Experimental data on the solubility of pharmaceutical substances in supercritical carbon dioxide have been gained, and empirical binary molecular interaction parameters for the Peng–Robinson equation have been derived. A numerical solution has been obtained for the unified model of nucleation and particle growth (in the drop theory approximation) in the expansion of a steady-state, two-dimensional, viscous, axisymmetric, compressible, supercritical carbon dioxide–pharmaceutical substance flow in a channel with a constant cross section and in a free jet. The correlation parameter of the condensation function, which characterizes the particle growth kinetics, has been determined.