http://www.bdtd.uerj.br/handle/1/3708 2026-05-11T18:07:22Z http://www.bdtd.uerj.br/handle/1/25545 Título: Estudos exploratórios para a síntese do precursor da 4-D,L-boronofenilalanina e para a oxidação da água na presença do hidróxido duplo lamelar de Cu/Al como catalisador Autor: Bomfim, Joice Florenço Primeiro orientador: Senra, Jaqueline Dias Abstract: Layered double hydroxides (LDHs) are anionic clays with different functional properties, being widely used as catalysts or supports in several reactions activated in the basic medium. Two classes of reactions of interest involve the organometallic reactions of Miyaura – which allow obtaining borylated compounds – and the oxygen evolution reaction, within the energetic context of the production of green hydrogen. In the form of composites with metallic nanoparticles, LDHs have also been used efficiently due to the synergistic effect between the metallic sites of the matrix and the nanoparticles. In view of the interesting catalytic properties of Cu(II) and Pd(0/II) species for the aforementioned reactions, this work proposes the synthesis of nanocomposites of Cu/Al LDHs. The characterization of the materials was performed using X-ray diffraction, infrared spectroscopy and UV-vis spectroscopy. The characterization of reactants and products proceeded by 1H and 13C nuclear magnetic resonance, and linear and cyclic scanning voltammetry. Catalytic tests with the compound of LDH with Pd in the electrooxidation reaction of water indicated low reproducibility and instability of the material; however, it was found a potential window and a sweep speed that the material stabilizes on the film. The overpotential at current density of 10 mA cm-2 in an FTO electrode was 1128 mV for pure LDH, and 1095 mV for LDH with palladium. Although these values demonstrate the low electrocatalytic activity of the material, it was possible to observe a slight improvement due to the presence of Pd(II) in the composite. The use of 4-bromophenylalanine in the preliminary borylation tests revealed little reactivity and solubility difficulties in the solvents tested for the reaction. Thus, it was decided to use the L-phenylalanine ethyl ester hydrochloride reagent with amino and iodinated protection. The formation of a product was observed, however, without certainty of the exact structure. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2023-08-30T00:00:00Z http://www.bdtd.uerj.br/handle/1/25431 Título: Fotocatalisadores à base de SnO2-TiO2 na forma de pó e como filme compósito com quitosana para degradação de corante catiônico sob luz UV e visível Autor: Etshindo, Lourdes Akaho Primeiro orientador: Rocha, Angela Sanches Abstract: Semiconductors can act as photocatalysts when activated by electromagnetic radiation, promoting the degradation of persistent organic compounds. TiO₂ is widely studied for its efficiency but faces limitations such as charges recombination and the difficult recovery of nanoparticles. The incorporation of SnO₂ and its immobilization in a composite film emerge as alternatives to enhance visible-light absorption and optimize the process. In this work, 0, 1, and 10 wt% SnO₂ were incorporated into TiO₂ (SnO₂-TiO₂) via co-precipitation using the sol-gel method with ammonia addition, with and without HCl, followed by calcination at 500 °C, distinguishing two synthesis routes. The photocatalysts were characterized by N₂ adsorption-desorption, FTIR spectroscopy, X-ray diffraction with Rietveld refinement, TG-DTG, scanning electron microscopy with EDS, UV-Vis diffuse reflectance spectroscopy (DRS), and elemental analysis. The performance of all solids was evaluated in the photocatalytic degradation of the cationic dye methylene blue in aqueous phase under visible and UV light at 25 °C for 2 hours, assessed by spectrophotometric measurements. TG results indicated that the calcination temperature used was sufficient for precursor decomposition. The Sn content matched the nominal values, suggesting no preferential precipitation under the conditions applied. Sn incorporation into TiO₂ improved the textural properties, increasing the specific surface area when HCl was used, and reduced the band gap compared to pure TiO₂. All solids exhibited XRD patterns typical of TiO₂, with anatase as the main phase; however, the catalyst containing 10% SnO₂ also showed the brookite phase, suggesting that Sn atoms incorporated into the TiO₂ structure promote the formation of this phase. All photocatalysts demonstrated high activity under both UV and visible light under the applied conditions. Although materials synthesized with HCl were not good adsorbents, they still showed high photocatalytic activity. The 10% SnO₂ material achieved 83% and 88% degradation after 2 hours under UV and visible radiation, respectively, and was tested as a film immobilized in chitosan, achieving 14% discoloration. The reuse of this film showed no loss of activity, even after the fourth use, and it remained adhered to the substrate. This investigation points to the potential use of SnO₂-TiO₂ photocatalysts to decompose a dye under both UV and visible light in powder form and as immobilized films in chitosan composites, opening possibilities for solar light utilization. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Tese 2025-07-15T00:00:00Z http://www.bdtd.uerj.br/handle/1/25405 Título: Preparação de resinas magnéticas à base de poli(acrilonitrila-co-divinilbenzeno) contendo grupos amidoxima para remoção de azul de metileno de meio aquoso Autor: Feitosa, Isabelle Ramos Primeiro orientador: Costa, Marcos Antônio da Silva Abstract: This Dissertation describes the synthesis, characterization and adsorptive evaluation of magnetic poly(acrylonitrile-co-divinylbenzene) resins functionalized with amidoxime groups, aiming at the removal of methylene blue from aqueous media. The resins were obtained by polymerization in aqueous suspension, using toluene or methyl benzoate as porogenic agents and magnetite previously stabilized with oleic acid as the magnetic phase. The functionalization of the resins by amidoximation was confirmed by FTIR spectroscopy, accompanied by morphological and textural changes evaluated by scanning electron mi- croscopy (SEM), thermogravimetry (TGA), Vibrating Sample Magnetometry (VSM) and mercury porosimetry. The results showed that the type of diluent plays a determining role in the porous structure of the material, with the resins synthesized with toluene and higher magnetite content (20%) being those that presented the largest surface area and pore volume, compared to those prepared with methyl benzoate. The presence of amidoxime groups in the polymeric structure resulted in a significant increase in the adsorption capacity of the dye. Among all the samples, the resin prepared using toluene as diluent and 20% magnetic material (TOL20MA) showed the best performance, removing more than 99% of methylene blue under the conditions evaluated, with kinetics adjusted to the pseudo-second order model. These results demonstrate the potential of amidoximated magnetic resins as efficient adsorbents for cationic dyes, highlighting the relevance of pore engineering and selective functionalization for optimizing performance in effluent treatment processes. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2025-09-19T00:00:00Z http://www.bdtd.uerj.br/handle/1/25203 Título: Estudo exploratório da síntese de catalisadores à base de óxido de nióbio usando surfactantes por rota sol-gel Autor: Braga, Bruno Matassoli Primeiro orientador: Rocha, Angela Sanches Abstract: Most industrial processes for the synthesis of chemical substances involve the use of catalysts, and the replacement of homogeneous catalysts with heterogeneous ones, which are easier to separate and reuse, has been a global trend. In this context, it is necessary to develop solids with peculiar catalytic properties, and, as Brazil is the world's largest producer of niobium, developing technology for the synthesis of catalysts containing this element is strategic for the nation. Niobium oxide (niobia) is an acidic solid, but the commercial material has a modest specific area, which may limit its use as a catalyst. One strategy used to obtain materials with a high area involves the use of routes that produce materials with a more open pore structure, such as sol-gel synthesis. There are only a few studies on the synthesis of mesoporous niobia obtained from surfactants, and the niobium precursors used are expensive and sensitive to air, making the process more expensive. Based on the above, the objective of this work is to investigate the synthesis of niobium-based solid acid catalysts via the sol-gel route, using amines as structure drivers, to generate materials with better textural properties than commercial ones. As an innovation, the niobium oxaloammonium complex was used, which is cheaper and easier to handle than niobium pentachloride and niobium pentaethoxide. The hydrothermal synthesis was carried out in an autoclave, using tetradecylamine and dodecylamine as structure drivers, and their removal was investigated. To increase acidity, three materials were sulfated with sulfuric acid. The materials involved were characterized by nitrogen adsorption, X-ray diffraction, thermogravimetry and infrared absorption spectroscopy. Some materials were tested in the esterification of acetic acid with ethanol at 1 atm and 70 °C, as it is a simple model reaction that fits among those used in the processing of bio-oil. The results indicated that it was possible to synthesize a mesoporous niobia from the ammoniacal niobium complex using tetradecylamine, although the surfactant removal procedure was critical. However, when dodecylamine is used, the results show that the same porous structure was not obtained, despite the areas being larger than that of commercial niobia, and surfactant removal is more efficient by combining acid washing and heat treatment. The synthesized niobias did not show activity in the esterification of acetic acid under the conditions used, but the sulfated materials were active and one of the catalysts had a conversion of almost 40% after 2 h of reaction, even using 0.5% by mass of the catalyst, opening the possibility of using these materials as acid catalysts. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2024-10-30T00:00:00Z