Sublimation Rate of TNT Microcrystals in Air

Abstract

Reliable measurements of the sublimation rate of nonuniform layers of trinitrotoluene (TNT) microcrystals were carried out using a quartz crystal microbalance (QCM). The sample layer was prepared by precipitation of TNT from a well-defined volume of its solution in acetonitrile. The TNT solution was placed on the QCM electrode surface to form the precipitated layer of TNT microcrystals. It is shown that the kinetics of small TNT particles sublimation is controlled by the molecular diffusion in air. The sublimation process is well described by simple diffusion expressions that are discussed in the literature for both individual hemisphericalshaped microcrystals and disk-shaped layers. Expressions describing particle size evolution in time were derived based on this diffusion model. It is shown that the expressions developed can be used to simulate particle sublimation in a wide size range, including very small sub-micrometer particles.

Inkjet-Printed Silver Nanoparticle Paper Detects Airborne Species from Crystalline Explosives and Their Ultratrace Residues in Open Environment

“…30 The molecular motion is a quasi-stationary steady-state diffusion and transport process. The solution of molecular concentration (C) at the distance H is 31…”

Rapid Estimation of Thermodynamic Parameters and Vapor Pressures of Volatile Materials at Nanoscale

“…In Figure 6 b, the non-isothermally determined vapor pressure values of TNT are compared to those determined isothermally, [13] and those reported in the literature. [5,8,[25][26][27] This indicates that absorbance spectroscopy can be used as an accurate, rapid estimation method of the vapor pressure of TNT. The discrepancy of the vapor pressure values of TNT in the literature increases with an increase in temperature as a result of the expected dissociation of the studied materials at temperatures closer to their melting points.…”

“…A variety of direct and indirect methods has been used to determine thermodynamic parameters as well as vapor pressures of volatile solid materials. Quartz crystal microbalance (QCM) [8] and atomic force microscopy (AFM) [9,10] are the only techniques that have been used to isothermally determine thermodynamic parameters at nanoscale with results indicating QCM to be a more efficient method. [6,7] TGA often requires a flow of gas through both the balance chamber and the sample.…”

“…[1][2][3][4][5] Thermogravimetric analysis (TGA) is the only known method used to determine such parameters non-isothermally for materials in bulk form. [8] The use of AFM to determine vapor pressures of materials at nanoscale has not been reported in the literature. Quartz crystal microbalance (QCM) [8] and atomic force microscopy (AFM) [9,10] are the only techniques that have been used to isothermally determine thermodynamic parameters at nanoscale with results indicating QCM to be a more efficient method.…”

Ein bioinspirierter nanostrukturierter Sensor für die Detektion von sehr niedrigen Sprengstoffkonzentrationen

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