Iodine-containing aluminum-based fuels for inactivation of bioaerosols

Inactivation of aerosolized biologically viable Bacillus atrophaeus endospores (stimulant of the B. anthracis bio-agent) in combustion products of air-acetylene flames seeded with different aluminum-based powders was investigated. A flow of bioaerosol was introduced into the environment above the flame. The mixing of the combustion products with bioaerosol particles occurred when the combustion temperatures were cooled off to approximately 170–260 °C (the cross-sectional weighted average temperature). The flame was seeded with pure Al powder as well as with composite Al·I2 and Al·B·I2 powders prepared by mechanical milling. The iodine content was close to 20 and 15 wt.% for Al·I2 and Al·B·I2 powders, respectively. The burn rate was highest for particles of pure Al and lowest for particles of Al·B·I2. It was also observed that in the flame, particles of Al·B·I2 had the lowest temperature compared to other materials. Despite a lower iodine concentration, the combustion products from the flame seeded with Al·B·I2 exhibited the highest levels of inactivation of the aerosolized spores. The flame products of Al·I2 have also shown an effective inactivation. The inactivation levels observed for the unseeded flame and flame containing pure Al, were much lower and similar to each other; these inactivation levels were consistent with relatively weak thermal stress experienced by the bioaerosol at the relatively low temperatures of the exhaust gas. The highest level of inactivation observed for the combustion products of Al·B·I2 composite powder is attributed to its lower burn rate and respectively more homogeneous mixing of the iodine-containing products with the exhaust gases.