Particle sizing in colloidal dispersions by ultrasound. Model calibration and sensitivity analysis

In this paper, the use of ultrasonics for the determination of particle size distributions (PSDs) in suspensions and emulsions is discussed. Focusing on systems with a large density difference between the dispersed and continuous phases, a mathematical model is used to correlate the primary measurement-the attenuation of acoustic waves as a function of frequency-to the PSD, and it becomes clear that the quality of the PSD thus obtained is directly related to the accuracy of the model parameters. To overcome possible problems in the case of incomplete physical-property information, we have developed a generalized procedure for particle sizing, based on a parametric sensitivity analysis and parameter calibration. The latter allows for computation of physical properties from acoustic data provided that the PSD is known. Moreover, particle sizing results are presented for dispersions of different sizes and materials, and compared to the findings of electron microscopy and dynamic light scattering.