In this work, new glass compositions were prepared in the ternary system GeO 2 -K 2 O-Ta 2 O 5 . Potassium oxide was added to reach the complete melt of the starting mixture and two composition series were investigated: the first one with a constant K 2 O molar content of 10% in the ternary system (90-x) GeO 2 -10K 2 O-xTa 2 O 5 and the second one with the same molar content of K 2 O and Ta 2 O 5 in the ternary system (100-2x)GeO 2 -xK 2 O-xTa 2 O 5 . Homogeneous and transparent glasses could be obtained between x = 0 and 20. X-ray diffraction analyzes of samples with x = 25 identified orthorhombic Ta 2 O 5 in the first series and an isostructure of K 3.8 Ge 3 Nb 5 O 20.4 in the second series where it is assumed that Ta 5+ ions are inserted in the Nb 5+ sites. As one of our goal with these materials is related with the preparation of glass-ceramics containing Ta 2 O 5 nanocrystals, the first series has been selected for further characterizations. An increase in glass-transition temperatures with increasing Ta 2 O 5 content as well as an increase of the thermal stability from x = 0 to 10 has been identified by differential scanning calorimetry. For higher contents, crystallization events were identified. Fourier transform infrared and Raman spectroscopic characterizations allowed to point out the intermediary behavior of Ta 2 O 5 in the vitreous network where TaO 6 octahedra are inserted inside the germanate network with TaO 6 clusters identified at higher Ta 2 O 5 contents. Heat-treated samples with high tantalum contents (x = 15 and 20) exhibit preferential precipitation of orthorhombic Ta 2 O 5 with nanometric size, suggesting the possibility of obtaining transparent glassceramics for optical applications.
Photolytic degradation of fluoxetine (FLX), a medicine commonly known as Prozac ® , was evaluated by using different photochemical processes. The ultraviolet/microwave (UV/MW) process showed higher efficiency in all the aspects evaluated in this study. The energy consumption was equivalent to 1.94 × 10-4 kW h mg-1 L (UV/MW), while in the UV process the value was 1.20 × 10-2 kW h mg-1 L. The degradation kinetics were applied to the FLX, with rate constant (k) = 0.15 ± 0.01 min-1 and linear correlation coefficient (R 2) = 0.980 for UV, and k = 6.15 ± 0.08 min-1 and R 2 = 0.998 for UV/MW. The FLX degradation of 99.16% (UV/MW 5 min) and 98.90% (UV 120 min) were observed, evidencing higher efficiency for the first process. The monitoring of transformation products (TPs) through chromatographic analysis enabled the identification of 9 TPs, proving that for the UV/MW process, the hydroxylated structures are verified in high quantity.
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