Isoconversional kinetic study of alachlor and metolachlor vaporization by thermal analysis

Abstract

The vaporization kinetics of two acetamide pesticides, namely alachlor and metolachlor, was studied by thermogravimetric analysis under nonisothermal conditions (using heating rates between 1.0 and 10 K min −1 ). A model-free isoconversional method of kinetic analysis was proposed, and activation energy dependences on the extent of conversion α for nonisothermal experiments were given. An increase in activation energy is shown for alachlor from 50 to 60 kJ mol −1 , while E values do not significantly vary in the range α > 0.1: 63 kJ mol −1 for metolachlor while 60 kJ mol −1 for alachlor. At the end of vaporization (0.9 < α < 1.0), the activation energies are in close agreement with the enthalpies of vaporization calculated from DSC measurements. C

Kinetics and vaporization of anil in nitrogen atmosphere – Non-isothermal condition

“…Similar type of effect is observed in the study of dichloroglyoxime (Pourmortazavi et al, 2007). The value of activation energy E a changes slightly with a which suggests that the vaporization stage is a single step (Sbirrazzuoli et al, 2005). The average values of E a energy of vaporization are 26.92 ± 1.90 kJ mol À1 (0.20 6 a 6 0.90, Friedman method).…”

Thermogravimetric measurement of the equilibrium vapour pressure: Application to water and triethanolamine

“…TG experiments carried at constant heating rate are very suited to perform kinetic analyses such as isoconversional [21][22][23][24] and Kissinger [25] methods to obtain the activation energy of the process. We will analyse the limitations of using these methods to determine the evaporation enthalpy.…”

Thermal Analysis

“…78 energies derived from DSC and FT-IR agree well whereas TMA data give rise to markedly smaller values. Sbirrazzuoli et al (70) have applied isoconversional kinetic analysis to the vaporization kinetics of alachlor and metolachlor and found that the obtained activation energies are consistent with the respective enthalpies of vaporization. Hazra et al (71) have used DSC and TGA to study vaporization kinetics of some essential oils and their key components.…”