A combined kinetic study on the pyrolysis of chrome shavings by thermogravimetry

Abstract

Chrome shavings (CS), a kind of solid wastes discharged from tanneries, always pose serious environmental problems due to the presence of chromium. In this work, kinetic study of the pyrolysis of CS was investigated using a thermogravimetric analyzer in nitrogen atmosphere. The results obtained from the thermogravimetric analysis indicated that there are three stages in the temperature range 25 to 600 °C. The second stage is the main weight loss stage and it could be mainly attributed to the pyrolysis of collagenous materials. Iso-conversional and generalized master-plots method were first employed to estimate the activation energy value and possible reaction mechanism of CS pyrolysis. The results showed that the pyrolysis process could not be described accurately by single-step reaction due to the heterogeneous nature of CS. Afterwards, the thermogravimetric kinetic of CS pyrolysis was studied using combined kinetic analysis. It was found that three-parallel-reaction model allowed better fitting relevance for CS pyrolysis. This information was important for simulating and predicting the pyrolysis behaviors of CS.

Keywords

• Chrome shavings
• Combined kinetics
• Pyrolysis
• Thermogravimetry