New insights into the thermal behavior and stability of ammonium bifluoride: non-isothermal thermokinetic analysis

A.C.J. RESENTERA; M.R ESQUIVEL; M.H.RODRIGUEZ

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

SPRINGER

Lugar: Berlin; Año: 2023

1388-6150

In this research, the thermal behavior of NH4HF2 was studied by non-isothermalthermogravimetric analysis between 298 and 600 K in a nitrogen atmosphere. Thethermal analysis indicated that the gasification of this material begins in the solid statefrom 343 K, approximately, and continues after the melting point (398 K) in the liquidstate. The Friedman´s isoconversional method and combined kinetic analysis wereused to evaluate the thermokinetic characteristics of the gasification of this compoundin solid and liquid states. The results show that both processes follow an F0 model withEaSol = 71.3 kJ mol-1 and ln(ASol/s-1) = 12.8, and EaLiq = 66.6 kJ mol-1 andln(ALiq/s-1) = 11.5. The kinetic triplets were corroborated by reconstructing the originalexperimental curves and predicting curves obtained under experimental conditionsdifferent from those used in the study. The F0 model indicates that the processes aredominated by sublimation/vaporization. The released gases were condensed andcharacterized, suggesting the formation of a new species, the “NH4HF2 gas”