Experimental study of aerodynamic resuspension of RDX residue

Abstract

Residues of hazardous substances, such as chemical compounds with low vapor pressure, radioactive particles, or biological contamination can remain on surfaces for a prolonged period of time. The fate of these particles partially depends on the aerodynamic resuspension rates from the surfaces that are a function of particle and surface properties as well as the environmental conditions. The aerodynamic resuspension can be used for non-contact surface sampling. The removal rates of microscopic explosive trimethylenetrinitramine (RDX) particles from smooth glass surfaces in a controlled flow environment are investigated in this paper. The shear stress in the flow cell is calculated using computational fluid dynamics as a function of velocity. The RDX particle samples are prepared by dry transfer. Particle sizes and morphologies are measured by 3D scanning electron microscopy (SEM) and optical profilometry. The resuspension rates are calculated based on the changes in the total coverage area before and after exposure to aerodynamic forces. These rates are correlated with wall shear stresses, particle size, and morphology. For non-spherical particles, the removal rates are proportional to the particle shape factor defined as a ratio of particle height to the projected equivalent diameter.

Copyright © 2019 American Association for Aerosol Research

Additional information

Funding

This work was supported by the DHS Science and Technology Directorate, and UK Home Office [grant no. HSHQDC-15-C-B0033] and was facilitated using advanced computational and the networking infrastructure provided by the Hyak supercomputer system at the University of Washington. Part of this work was conducted at the Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure site at the University of Washington which is supported in part by the National Science Foundation [grant ECC-1542101], the University of Washington, the Molecular Engineering & Sciences Institute, the Clean Energy Institute, and the National Institutes of Health.