Physics-based agent to simulant correlations for vapor phase mass transport.
Chemical warfare agent simulants are often used as an agent surrogate to perform environmental testing, mitigating exposure hazards. This work specifically addresses the assessment of downwind agent vapor concentration resulting from an evaporating simulant droplet. A previously developed methodology was used to estimate the mass diffusivities of the chemical warfare agent simulants methyl salicylate, 2-chloroethyl ethyl sulfide, di-ethyl malonate, and chloroethyl phenyl sulfide. Along with the diffusivity of the chemical warfare agent bis(2-chloroethyl) sulfide, the simulant diffusivities were used in an advection-diffusion model to predict the vapor concentrations downwind from an evaporating droplet of each chemical at various wind velocities and temperatures. The results demonstrate that the simulant-to-agent concentration ratio and the corresponding vapor pressure ratio are equivalent under certain conditions. Specifically, the relationship is valid within ranges of measurement locations relative to the evaporating droplet and observation times. The valid ranges depend on the relative transport properties of the agent and simulant, and whether vapor transport is diffusion or advection dominant.
Decontamination Sciences Branch, U.S. Army Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, MD 21010-5424, United States. Electronic address: matthew.p.willis.civ@mail.mil.
Matthew P
MP
Willis
Mark J
MJ
Varady
Thomas P
TP
Pearl
Janet C
JC
Fouse
Patrick C
PC
Riley
Brent A
BA
Mantooth
Teri A
TA
Lalain
D000393:Air Pollutants / Q000032:analysis*; D002619:Chemical Warfare Agents / Q000032:analysis*; D003666:Decontamination / Q000379:methods; D004058:Diffusion; D004784:Environmental Monitoring / Q000379:methods; D052918:Environmental Restoration and Remediation; D005740:Gases; D008314:Malonates / Q000032:analysis; D008962:Models, Theoretical; D008970:Molecular Weight; D009151:Mustard Gas / Q000031:analogs & derivatives / Q000032:analysis; D010316:Particle Size; D015203:Reproducibility of Results; D012459:Salicylates / Q000032:analysis; D013440:Sulfides / Q000032:analysis; D013696:Temperature
D000393:Air Pollutants; D002619:Chemical Warfare Agents; D005740:Gases; D008314:Malonates; D012459:Salicylates; D013440:Sulfides; C498810:diethyl malonate; C031278:2-chloroethyl ethyl sulfide; C033069:methyl salicylate; D009151:Mustard Gas
Chemical warfare agent; Chemical warfare simulants; HD; Parameter estimation; Physics-based models; Vapor emission hazards