Effect of semiconducting metal oxide additives on the kinetics of thermal decomposition of sodium oxalate under isothermal conditions

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• 作者：M. Jose John¹ ; K. Muraleedharan ; ^{kmuralika@gmail.com} ; M.P. Kannan ; T. Ganga Devi
• 关键词：Contracting cylinder equation ; Diffusion controlled mechanism ; Isothermal decomposition kinetics ; Prout&ndash ; Tompkins equation ; Semiconducting metal oxide additives ; Sodium oxalate
• 刊名：Thermochimica Acta
• 出版年：2012
• 期刊代码：110_00406031
• 类别：ch
• 出版时间：20 April, 2012
• 卷：534
• 期：Complete
• 页码：71-76
• 文件大小：393 K

摘要

The effect of semiconducting metal oxide (CuO and TiO₂) additives on the kinetics of thermal decomposition of sodium oxalate (Na₂C₂O₄) to sodium carbonate has been studied at five different temperatures in the range 783-803 K under isothermal conditions by thermogravimetry (TG). Irrespective of whether p- or n-type, the metal oxides show an increase in the rates of both stages of decomposition up to an oxide concentration of 1 wt%and then decreases (at higher concentrations). The TG data were subjected to model fitting kinetic methods of analysis. The rate law for the decomposition of Na₂C₂O₄ (Prout-Tompkins and contracting cylinder models respectively for the acceleratory and decay stages) remained unaffected by the additives. Similar effects were observed with pre-compressed metal oxide additives on the thermal decomposition of Na₂C₂O₄. The results support the diffusion controlled mechanism proposed earlier for the isothermal decomposition of sodium oxalate.