Mechanism and kinetics of the oxidation of synthetic alpha-NiS

Abstract

The results of an investigation of the mechanism and kinetics of the oxidation process of synthetic a-NiS are presented in this paper. The mechanism of a-NiS oxidation was investigated based on the comparative analysis of DTA–TG–DTG and XRD results, as well as the constructed phase stability diagrams (PSD) for the Ni–S–O system. The kinetic investigations of the oxidation process were performed under isothermal conditions (temperature range 823–1073 K). The obtained degrees of desulfurization were used in the calculation process according to the Sharp model and the kinetic parameters, including the activation energies and the rate constants of the characteristic reactions, for the oxidation of a-NiS were determined. These results enabled the formulation of a kinetic equation for the desulfurization process: ‑ln(1−a) = k1t = 27.89 exp(–9860/T)t, with an activation energy of 82±4 kJ mol-1, for the first stage of the process and –ln (1 − a) = k2t = 1.177 exp(–4810/T)t, with an activation energy of 40±2 kJ mol-1, for the second stage.

Keywords

• anti-inflammatory agents
• potentiometric titration
• artificial neural network (ANN)