Abstract
Conventional particle size analysis by sedimentation method does not give true size distributions but only apparent ones, when Brownian coagulation and Brownian diffusion exist. The difference of true and apparent size distributions was theoretically evaluated by numerically solving the population balance equation under various conditions. Then some of the theoretical results were verified experimentally for particles having various sizes and number concentrations which were obtained under sedimentation in air, in water and in centrifugal field by means of ultramicroscopic size analysis. In addition to these analyses, two parameters consisting of given measuring conditions, which were proposed herein, were found to be useful to predict whether or not coagulation and diffusion effects exist in actually observed size distributions.
