Break-Up and bounce of TiO2 agglomerates by impaction

In this study, the impaction behavior of titanium dioxide (TiO2) agglomerates is evaluated, and the described method allows for the break-up and bounce of the particles to be monitored simultaneously. The degree of sintering and the primary particle size of the TiO2 agglomerates were varied. The agglomerates were impacted onto the impaction plate of a single-stage micro-orifice uniform impactor, after which the bounced particles were collected in a low-pressure sampling chamber for subsequent analyses. The particle trajectories were simulated to accurately estimate the impaction velocity, which is one of the key parameters in the impaction process. A high degree of sintering significantly reduced the number of broken bonds, whereas reducing the primary particle size caused only minor differences in the number of broken bonds. The particles that bounced but did not break up either had a smaller primary particle size or were sintered. Decreasing the primary particle size also reduced the mass-based fraction of the bouncing particles.