The catalytic thermo-oxidative decomposition of glimepiride using the isoconversional method
Najamus Sahar Riyaz, Ismail Badran
Abstract
Abstract Applying the isoconversional method to data obtained from thermogravimetric analysis (TGA) can provide vital kinetic information. In this work, the thermal decomposition and oxidation of the antidiabetic drug glimepiride is analyzed in the presence of N 2 and O 2 . The study was done with and without metal oxide catalysts to explore their potential application in solid wastewater upgrading. The analysis was conducted using thermogravimetric analysis. The isoconversional methods of Kissinger–Akahira–Sunose and Friedman were used to estimate the effective activation energies as a function of the extent of conversion ( α ). Density functional calculations were used to estimate the bond dissociation energies in glimepiride. The E a values obtained from the Friedman method and the DFT calculations indicate an initial S–N bond breaking in glimepiride. The pre-exponential factor ( A ) and the kinetic triplet (Δ H ‡ , Δ S ‡ , and Δ G ‡ ) are also discussed. When glimepiride oxidation was studied in the presence of the metal oxides, the catalyst activity was found to follow the order $${\text{VO}}_{{2}} > {\text{ CuO }} > {\text{ MnO}}_{{2}} > {\text{ Al}}_{{2}} {\text{O}}_{{3}} > {\text{ TiO}}_{{2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mtext>VO</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:mo>></mml:mo><mml:mrow><mml:mspace/><mml:mtext>CuO</mml:mtext><mml:mspace/></mml:mrow><mml:mo>></mml:mo><mml:msub><mml:mrow><mml:mspace/><mml:mtext>MnO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mo>></mml:mo><mml:msub><mml:mrow><mml:mspace/><mml:mtext>Al</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mn>3</mml:mn></mml:msub><mml:mo>></mml:mo><mml:msub><mml:mrow><mml:mspace/><mml:mtext>TiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> .