Kinetic analysis of nicotine desorption from silicon dioxide under non-isothermal conditions

Abstract

Abstract The non-isothermal kinetics of nicotine desorption from precipitated silicon dioxide was investigated. The non-isothermal thermogravimetric curves of nicotine desorption at different heating rates (β = 5, 10 and 20 K/min) were recorded. The kinetics model of non-isothermal kinetics of nicotine desorption was determined by using the model-fitting and master-plot methods. It was found that non-isothermal nicotine desorption can mathematically describe by the theoretical kinetics model of phase – boundary controlled reaction (contracting volume, i.e., three dimensional shape) – R3. By applying the method of Kissinger and method of invariant kinetic parameters the values of kinetic parameters were determined. It was established that both applied method give almost identical kinetic parameters regardless their theoretical limitations. The dependence of activation energy on the degree of nicotine desorption was determined using the KAS method. It was found that the value of activation energy is independent on the degree of nicotine desorption. The effect of heating mode on the kinetic of nicotine desorption was analyzed. It was established that the type of heating mode (isothermal and non-isothermal) does not influence the mechanism of the formation of the activation complex nor the kinetics model of desorption. The increase in the values of kinetic parameters obtained for non-isothermal heating in comparison to the isothermal ones are explained with the Larson's model of selective transfer of energy.