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Preparation and Thermal Decomposition Kinetics of Polyoxometalate of Ciprofloxacin with 12‐Tungstosilicic Acid
Author(s) -
Wang DunJia,
Fang ZhengDong,
Wei XianHong
Publication year - 2005
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200591600
Subject(s) - polyoxometalate , chemistry , thermal decomposition , keggin structure , aqueous solution , infrared spectroscopy , decomposition , elemental analysis , thermal analysis , inorganic chemistry , nuclear chemistry , analytical chemistry (journal) , crystallography , catalysis , organic chemistry , thermal , physics , meteorology
A new polyoxometalate (CPFX·HCl) 3 H 4 SiW 12 O 40 ·10H 2 O was prepared from ciprofloxacin hydrochloride and H 4 SiW 12 O 40 · n H 2 O in aqueous solution, and characterized by elemental analysis, IR spectra and DTA‐TG‐DTG techniques. The IR spectrum confirmed the presence of Keggin structure and the characteristic functional group for ciprofloxacin in the compound. The TG‐DTA‐DTG curves showed that its thermal decomposition was a four‐step process consisting of simultaneous collapse of Keggin type structure. The residue of decomposition was the mixture of WO 3 and SiO 2 , confirmed by X‐ray diffraction and IR spectroscopy. The decomposition mechanism and non‐isothermal kinetic parameters of the polyoxometalate were obtained from an analysis to the TG‐DTG curves by the single scanning methods (the Achar method and Coats‐Redfern method) and the multiple scanning methods (the Kissinger method, Flynn‐Wall‐Ozawa method and Starink method). The results indicate that the kinetic equations with parameters describing the thermal decomposition reaction are d α /d t =6.65×10 6 [3(1− α ) (2/3) ]e (−10495.5/ T ) with E =87.26 kJ/mol and A =6.65×10 6 s −1 for the second step, d α /d t =7.01×10 9 (1− α )e (−18770.7/ T ) with E =156.06 kJ/mol and A =7.01×10 9 s −1 for the third step, d α /d t =9.77×10 43 [(1− α ) 2 ]e (−88980.0/ T ) with E =739.78 kJ/mol and A =9.77×10 43 s −1 for the fourth step.