Fe-doped titanium dioxide synthesized: Photocatalytic activity and mineralization study for azo dye

Photocatalytic bleaching and mineralization of the dye Cibacron Yellow LS-R using Fe-doped TiO2 synthesized and Aeroxide TiO2 P25 have been investigated. The Fe-doped TiO2 samples were synthesized by sol–gel method combined with solvothermal treatment at short crystallization time (2 h) and low temperature (200 °C), using tetraisopropyl orthotitanate as Ti-precursor, iron (III) nitrate as Fe-precursor and 2-propanol as solvent. Different Fe:Ti molar ratios (0.5%, 1%, 1.5% and 2%) were evaluated. 0.5% Fe-doped TiO2 had the best photocatalytic performance among Fe doped samples, however it showed a low photocatalytic activity in the dye Cibacron Yellow LS-R photodegradation compared with Aeroxide TiO2 P25. This result perhaps is due to the poor ability of the Fe-doped TiO2 to produce hydroxyl radicals under UV irradiation, which was measured using fluorescence method, and its size particle which could be very large for the iron load in the sample, compared with those reported in the literature as appropriate.

► Fluoride ion enhanced the generation of free OH, reducing recombination rate.
► Fluoride ion mineralization rate was higher than nitrate and sulfate mineralization.
► Fluorescence and TEM analysis could explain low degradation for iron doped titania.
► Hydroxyl radical production was tested using coumarin as a probe molecule.