Thermal Oxidative Degradation of Pure Cu2S and Industrial White Metal

Abstract

The kinetics of the thermal oxidation of white metal and Cu₂S have been studied by thermogravimetric analysis (TG), which was carried out under atmospheric oxidative conditions (O₂ 100%) with heating rates of 5, 10, 15 and 20 °C min⁻¹. Each experiment was performed three times, the indicated values being the average of the three experiments. The experimental data were evaluated using isoconversional models based on the Arrhenius equation. The models are constructed using first-order mechanisms in the reactions and therefore, since most of them present adequate regression coefficients, it can be verified that order 1 is the most predominant order among the reactions found. In addition, the Kissinger–Akahira–Sunose model, which has the highest regression coefficient, is considered to be the most optimal. Similar behavior was recorded between Cu₂S and white metal, as well as a similar regular increase in the apparent activation energy (Ea) of 10–30 kJ mol⁻¹ for both materials. The reactions that took place during the oxidation of white metal and Cu₂S were determined using a computational model based on thermodynamics developed in this work. The identified phases include CuSO₄, Cu₂SO₄, Cu₂O, CuO, CuO·CuSO₄.