Kinetic Treatment of Evaporation via Thermogravimetric Analysis: The Case of d-Limonene

Abstract

Evaporation from a surface under atmospheric conditions can be difficult to characterize because the process involves both thermodynamics and kinetics. Thermogravimetric analysis was used to study the evaporation of D-limonene under several nitrogen flow rates above the surface. Instead of the common thermodynamic analysis, a kinetic treatment resulted in an activation energy of evaporation that is mostly composed of the enthalpy of vaporization with a smaller, additional energy due to the diffusion of molecules through the laminar boundary layer above the evaporating surface. As the flow rate over the sample increased from 60 to 200 mL/min, the activation energy decreased from 57.3 to 49.7 kJ mol −1 and approached reported enthalpy of vaporization values. Thus thermogravimetric analysis can be used to quantitatively characterize both the kinetic and thermodynamic aspects of nonequilibrium evaporation processes.

Antibacterial Activity of Zinc Oxide Nanoparticles Loaded with Essential Oils

“…The samples obtained from orange and grapefruit essential oils exhibited the lowest total mass loss due to the low persistence of the loaded essential oils (estimated load of 1.44% and 1.93%, respectively). As the major component of these two essential oils was limonene (over 90%), it likely did not create strong enough bonds with ZnO NPs to avoid its rapid release by evaporation [68]. Nevertheless, the other minor components of essential oils, like linalool or β-myrcene were still present in the sample [69,70], and their degradation was followed by the elimination of water vapors, carbon dioxide, and some traces of hydrocarbon fragments at over 300 • C, as presented in Figures 7 and 8.…”

Designing Volatile Molybdenum Compounds for Vapour-Phase Deposition

“…Care must be taken to not over-interpret the comparison of TGA data collected on different instruments and by different research groups. This is because key parameters such as the onset of volatilization and residual mass are dependent on the heating rate of the experiment, 41,42 the flow rate of the carrier gas, 43 and the initial mass loading. 44,45 Specifically, changing the initial mass loading can increase Tonset due to a kinetic component of evaporation.…”