Kinetic studies on the thermal decomposition of aluminium doped sodium oxalate under isothermal conditions

• Published in: Thermochimica acta 2012-04, Vol.534, p.64-70
• Main Authors: Jose John, M., Muraleedharan, K., Kannan, M.P., Abdul Mujeeb, V.M., Ganga Devi, T.
• Format: Article
• Language: English
• Subjects: activation energy; Aluminium doping; Aluminum; Chemical thermodynamics; Chemistry; Contracting cylinder equation; Cylinders; Decomposition; Diffusion controlled mechanism; Exact sciences and technology; Fittings; General and physical chemistry; General. Theory; Isothermal thermogravimetry; Mathematical models; Oxalates; Prout–Tompkins equation; Reaction kinetics; Sodium; Sodium oxalate; temperature; thermal degradation; thermogravimetry
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2012.02.003

► Studies on the isothermal decomposition kinetics of Na2C2O4 in the range 783–803K by TG. ► Effect of aluminium dopant on the kinetics of thermal decomposition. ► Acceleratory and decay stages of the thermal decomposition follows different reaction models. ► Rate of decomposition is dependent on dopant concentration. ► Diffusion controlled mechanism is suggested for the thermal decomposition. The kinetics of thermal decomposition of sodium oxalate (Na2C2O4) has been studied as a function of concentration of dopant, aluminium, at five different temperatures in the range 783–803K under isothermal conditions by thermogravimetry (TG). The TG data were subjected to both model fitting and model free kinetic methods of analysis. The model fitting analysis of the TG data shows that no single kinetic model describes the whole α versus t curve with a single rate constant throughout the decomposition reaction. Separate kinetic analysis shows that Prout–Tompkins model best describes the acceleratory stage of the decomposition while the decay region is best fitted with the contracting cylinder model. Activation energy values were evaluated by model fitting and model free kinetic methods for both stages of decomposition. As proposed earlier the results favours a diffusion controlled mechanism for the isothermal decomposition of sodium oxalate.