Analyis of liquid mixing and solid dissolution for pharmaceutical manufacturing in stirred tanks

This work concerns solid-liquid mass transfer in stirred tanks and is focused on the analysis of experimental data collected during the dissolution of different solid materials in laboratory and industrial equipment. The times required for the solid dissolution and for the liquid mixing are considered, since they are key parameters of the operation. The adoption of literature correlations, which are proved to be applicable for the estimation of the two characteristic times in different applications, is suggested for obtaining useful indications on the dissolution operation depending on the equipment scale, coupling the approaches suggested so far for the analysis of liquid blending and solid dissolution processes. Available literature data concerning particle dissolution in pharmaceutical processes are taken for the models assessment. The applicability of the proposed method to the dissolution of powders for the home care industry is also considered. The outcome of this investigation can be adopted as a simple guideline for the selection of the operating conditions of the stirred vessels and for a proper choice of the solid size as a function of the vessel scale.