Iodine Release by Combustion of Composite Mg∙Ca(IO₃)₂ Powder

ABSTRACT

Concentration of iodine generated by combustion of a reactive material (RM) powder, Mg∙Ca(IO₃)₂, injected in an air-acetylene flame was measured as a function of height above the flame using absorption of collimated emission from a tunable laser diode. The absorption by atomic iodine was sufficient to be quantified when the powder feed rate into the flame was close to 50 mg/s. The measurements were compared to calculations using a simplifying assumption that iodine is released by burning RM particles at a constant rate during their combustion. The calculated iodine profiles were produced using a computational fluid mechanics model considering iodine released by burning RM particles. The particle size distribution was taken into account as well as the experimentally determined trend of particle burn times vs. their sizes. The predicted iodine release was split between molecular and atomic iodine according to the ratio between these species expected to be in thermal equilibrium at the flame temperatures. Both calculated and measured iodine concentrations exhibit similar increase and decrease as a function of height, suggesting that a constant rate of iodine release by a burning RM particle during its entire burn time may be a reasonable assumption. However, the absolute values of the measured concentrations of atomic iodine are lower than those predicted. This discrepancy may be attributed to the formation of other iodine-bearing species expected to be metastable for the temperatures involved.

KEYWORDS:

• Reactive materials
• agent defeat
• biocidal species
• laser absorption spectroscopy
• metal combustion

Additional information

Funding

This work was supported by the US Defense Threat Reduction Agency.