Fe-TiO 2 Nanoparticles Synthesized by Green Chemistry for Potential Application in Waste Water Photocatalytic Treatment

Anatase TiO 2 nanoparticles doped with iron ions have been synthesized via the green chemistry method using aqueous extract of lemongrass ( Cymbopogon citratus ) obtained from Soxhlet extraction and doped by wet impregnation. The TiO 2 anatase phase has been doped with Fe 3+ (0.05, 0.075, and 0.1 Fe 3+ : Ti molar ratio) at 550°C and 350°C, respectively. The scanning electron microscopy with energy-dispersive X-ray (SEM-EDS) shows nanoparticle clusters and efficiencies of impregnations between 66.5 and 58.4% depending on the theoretical dopant amount. The electron transmission microscopy (TEM) reveals final particle sizes ranging between 7 and 26 nm depending on the presence or not of the dopant. The cathodoluminescence (CL) and photoluminescence (PL) studies of the doped and undoped nanoparticles show a luminescence signal attributed to surface oxygen vacancies (visible CL emission 380–700 nm and PL emission 350–800 nm); additionally, a decrease in emission intensity is observed due the inhibition of the recombination of the photogenerated electron-holes pairs; moreover, nanopowders were analyzed by UV-Vis spectrophotometry of diffuse reflectance, and the absorption edge of the Fe-TiO 2 in comparison to undoped TiO 2 is extended greatly toward the visible light. The six bands (A 1g + 2B 1g + 3E g ) found by Raman spectroscopy and the x-ray diffraction pattern (XRD) confirm that synthesized TiO 2 is only anatase phase, which is commonly used as a catalyst in waste water treatment, specifically in heterogeneous photocatalytic processes.