Mesoporous TiO2 and Fe-containing TiO2 prepared by solution combustion synthesis as catalysts for the photodegradation of paracetamol.

Water pollution due to emerging contaminants, e.g., pharmaceuticals, is one of the most frequently discussed issues. Among them, paracetamol received great attention due to its physico-chemical properties, persistence, and adverse environmental effects. Different techniques were employed for its degradation and, among them, photodegradation is considered one of the most suitable to pursue the aim. This work aimed to synthesize mesoporous TiO2, even with the presence of iron, through a one-pot method, with an enhanced ability to abate paracetamol. Precisely, pure and iron-containing (3.5 wt%) TiO2 were successfully obtained employing an uncommon procedure for this kind of material, mainly solution combustion synthesis (SCS). Moreover, a traditional hydrothermal method and a commercial Degussa P25 were also investigated for comparison purposes. The samples were characterized through N2-physisorption at - 196 °C, XRD, XPS, EDX, DR UV-Vis, and FESEM analysis. The catalytic activity was investigated for the abatement of 10 ppm of paracetamol, under UV irradiation in acidic conditions (pH = 3) and in the presence of H2O2. As a whole, the best-performing catalysts were those obtained through the SCS procedure, highlighting a complete removal of the organic pollutant after 1 h in the case of Fe/TiO2_SCS, thanks to its highly defective structure and the presence of metal Fe. To better investigate the performance of both pure and Fe-containing SCS samples, further oxidation tests were performed at pH = 7 and in the absence of H2O2. Noteworthy, in these conditions, the two samples exhibited different behaviors, highlighting different mechanisms depending on the presence or absence of iron in the structure. Finally, a kinetic study was conducted, demonstrating that a first order is suitable for its abatement.

Reverse Micelle Strategy for the Synthesis of MnO x -TiO2 Active Catalysts for NH3-Selective Catalytic Reduction of NO x at Both Low Temperature and Low Mn Content.

MnO x -TiO2 catalysts (0, 1, 5, and 10 wt % Mn nominal content) for NH3-SCR (selective catalytic reduction) of NO x have been synthesized by the reverse micelle-assisted sol-gel procedure, with the aim of improving the dispersion of the active phase, usually poor when obtained by other synthesis methods (e.g., impregnation) and thereby lowering its amount. For comparison, a sample at nominal 10 wt % Mn was obtained by impregnation of the (undoped) TiO2 sample. The catalysts were characterized by using an integrated multitechnique approach, encompassing X-ray diffraction followed by Rietveld refinement, micro-Raman spectroscopy, N2 isotherm measurement at -196 °C, energy-dispersive X-ray analysis, diffuse reflectance UV-vis spectroscopy, temperature-programmed reduction technique, and X-ray photoelectron spectroscopy. The obtained results prove that the reverse micelle sol-gel approach allowed for enhancing the catalytic activity, in that the catalysts were active in a broad temperature range at a substantially low Mn loading, as compared to the impregnated catalyst. Particularly, the 5 wt % Mn catalyst showed the best NH3-SCR activity in terms of both NO x conversion (ca. 90%) and the amount of produced N2O (ca. 50 ppm) in the 200-250 °C temperature range.