Dustiness test of nanopowders using a standard rotating drum with a modified sampling train

The standard rotating drum tester was used to determine the dustiness of two nanopowders, nano-TiO₂ and fine ZnO, in standard 1-min tests. Then, the sampling train was modified to determine the number and mass distributions of the generated particles in the respirable size range using a Scanning Mobility Particle Sizer (SMPS), an Aerodynamic Particle Sizer (APS) and a Multi-orifice Uniform Deposit Impactor (MOUDI) in the 30-min tests. It was found that very few particles below 100 nm were generated and the released rate of particles decreased with increasing rotation time for both nanopowders in the 30-min tests. Due to the fluffy structure of the released TiO₂ agglomerated particles, the mass distributions measured by the MOUDI showed large differences with those determined by the APS assuming the apparent bulk densities of the powders. The differences were small for the ZnO agglomerates, which were more compact than the TiO₂ agglomerates.