Agglomerate fragmentation in high-intensity acoustic standing wave fields

The potential of high intensity ultrasound to cause fragmentation of agglomerated solid particles in air is investigated. The dispersion of single functionalized particulate agglomerates was achieved by application of a standing acoustic wave field. The particle trajectories indicate that the levitated agglomerates initially move in a sinusoidal pattern through the standing acoustic field due to their irregular shape. The frequency of the particle movement is orders of magnitude lower than the base frequency of the applied wave field and thus the agglomerates experience alternating external and internal stresses while moving through the field. Specific energy dependent agglomerate breakage probabilities are investigated by variation of the primary particle size, the degree of particle surface functionalization of the primary particles and the humidity of the surrounding gas atmosphere. (C) 2015 Elsevier B.V. All rights reserved.