Thermal dehydration kinetics of potassium bis(oxalato)cuprate(II) dihydrate

The potassium bis(oxalato)cuprate(II) dihydrate was synthesized, characterized using FT-IR and its non-isothermal dehydration was studied by differential scanning calorimetry and thermogravimetry at different heating rates. The kinetics of the thermal dehydration was investigated using different isoconversional and maximum rate (peak) methods using differential scanning calorimetric data. The activation energy values were also evaluated from thermogravimetric data using different model-free methods and the complexity of the dehydration is illustrated by the dependence of Eα on the extent of conversion. The Eα values obtained from all isoconversional methods shows a decrease with conversion, passes through a minimum at α = 0.4 and becomes almost steady in the range α = 0.5–0.95. The variation of Eα with conversion function, α, established using these different methods was found to be similar. We obtained an Eα value of ∼76 kJ mol−1 from different isoconversional methods which is reasonable than the huge values (411.5 ± 41.1 kJ mol−1) reported earlier.