This paper aims to explore the production of porous Nb2O5 pellets by pressing and adding anaerobic biomass (sludge) in order to evaluate the microstructure porosity. The thermal treatment temperature of the pellets varied between 300 ºC and 900 ºC. Their structural, morphological, and physical properties were measured, and the adsorption potential of Mn2+ and their reuse were evaluated. All samples had a monoclinic phase. Density average values of samples pressed using sludge ranged between 2.45 and 2.52 g.cm-3, while the one obtained without sludge pressing achieved higher values of around 2.72 g.cm-3. All samples presented high porosity values after the heat treatment (above 40%), which confirms the efficiency of sludge as a means to enhance porosity. These pellets were used for Mn2+ ions adsorption in aqueous medium. The Langmuir isotherm model was the one that achieved the best goodness-of-fit. In kinetic studies, the adsorption reaction was in accordance with second-order kinetics. Adsorbents in the form of pellets are environmentally friendly on account of their significant reuse and recycling potential. However, the particulate matter might become an environmental liability and incur high treatment costs. The samples proved to be reusable, promoting the adsorption of 67% of the Mn2+ after the fifth reuse cycle.

This paper describes the development of TiO2 and ZnO particles by a chemical route, using two different wet synthesis methods: polymeric precursor (PP) and sol-gel (SG). This study aimed to shed a light on how the synthesis method affects the photocatalytic activity of these oxides. Rhodamine B (RhB) degradation was used as a probe reaction to test the as-synthesized TiO2 and ZnO photoactivity. It was observed that surface availability, which is related to the presence of synthesis residue, is the key parameter to determine photoactivity. ZnO PP and ZnO SG presented degradation of 88% to RhB. Both samples presented synthesis residue on the surface. On the other hand, TiO2 PP presented a better performance than TiO2 SG, once 90% of RhB was degraded, while TiO2 SG degraded 80% of the dye. In this case, TiO2 PP was free of synthesis residue on the surface, while TiO2 SG presented residues.

This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful attainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm.