Reaction kinetics of nanometric aluminum and iodine pentoxide
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Owing to increasing threats of biological attacks, new methods for the neutralization of spore-forming bacteria are currently being examined. Thermites may be an effective method to produce high-temperature reactions, and some compositions such as aluminum (Al) and iodine pentoxide (I2O5) also have biocidal properties. This study examines the thermal degradation behavior of I2O5 mixed with micron and nanometer scale aluminum (Al) particles. Differential scanning calorimetry (DSC) and thermogravimetric (TG) analyses were performed in an argon environment on both particle scales revealing a non-reaction for micron Al and a complex multistep reaction for the nanometer scale Al. Results show that upon I2O5 decomposition, iodine ion sorption into the alumina shell passivating Al particles is the rate-controlling step of the Al–I2O5 reaction. This pre-ignition reaction is unique to nano-Al mixtures and attributed to the significantly higher specific surface area of the nanometric Al particles which provide increased sites for I− sorption. A similar pre-ignition reaction had previously been observed with fluoride ions and the alumina shell passivating Al particles.