http://www.bdtd.uerj.br/handle/1/3709 2026-03-14T16:51:43Z 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 http://www.bdtd.uerj.br/handle/1/25111 Título: Formação da estrutura porosa em microesferas de poli(acrilonitrila-co-divinilbenzeno) obtidas por polimerização em suspensão Autor: Nascimento, Adriano Furani do Primeiro orientador: Costa, Marcos Antonio da Silva Abstract: In this dissertation, acrylonitrile-divinylbenzene copolymers were synthesized by suspension polymerization, in the presence of three porogenic agents (methyl benzoate, toluene and heptane) in different dilution degrees and different levels of the crosslinking agent divinylbenzene. The copolymers were characterized in terms of bulk density, pore volume and pore diameter. The beads morphology were also analyzed by optical and scanning electron microscopy, while the chemical structure were determined by infrared spectroscopy. Hildebrand and Hansen solubility parameters were used to predict the porous structure of the beads and their predictions were compared to the characteristics of the copolymers. The results showed the formation of different porous structures, mainly due to the type of diluent used. The increase in the degree of dilution favored the increase in the pore size of the resins. The increase in the content of cross-linking agent had different behaviors, depending on the type of diluent used in the synthesis. The most solvating diluent, methyl benzoate, generated microporous beads, while the less solvating diluent,heptane, generated macroporous microspheres. The beads synthesized in the presence of toluene have a large distribution of pore sizes, depending on the composition of the monomeric mixture used. The predictions made by Hansen solubility parameters were very assertive regarding the morphology obtained with each diluent. Methyl benzoate proved to be a good solvent for the copolymers synthesized with all of the monomers composition studied in this dissertation. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2020-09-01T00:00:00Z http://www.bdtd.uerj.br/handle/1/24914 Título: Síntese e caracterização de poli(2-vinilpiridina-co-divinilbenzeno) para remoção de bisfenol A de meio aquoso Autor: Araujo, Tatyane Claudio Primeiro orientador: Costa, Marcos Antonio da Silva Abstract: Contaminants such as bisphenol A have gradually increased over the years, making human exposure increasingly inevitable. Its presence can already be detected in water bodies, even reaching drinking water. Therefore, due to contact with water, which is essential for life, contact with the environment and everyone who lives in it is a reality. Several studies have identified bisphenol A molecules as an endocrine disruptor capable of causing harm to various systems in the human body. This high risk has led national and international health agencies to establish exposure limit parameters to try to curb bisphenol A intake. In this scenario, it is necessary to test ways to remove this contaminant from nature. Among the possible methods is adsorption, a low-cost and highly advantageous method. The use of porous polymeric microspheres based on poly(2-vinylpyridine-co-divinylbenzene) for the adsorption of bisphenol A was the main objective of this work, since they promote, in addition to α-α interactions and electrostatic interactions, hydrogen interactions between the vinylpyridine groups. The polymeric resins were synthesized using the aqueous suspension polymerization technique and were characterized by FTIR, scanning electron microscopy, and thermal decomposition analysis. The reaction conditions studied for bisphenol A removal included aqueous media at room temperature, without any pH adjustments. Removal was monitored using a benchtop spectrophotometer, where the removal of approximately 0.354 mg/g of bisphenol A was observed, with a removal efficiency above 70%. Finally, the reuse of the adsorbent could be evaluated by desorbing bisphenol A in an alcoholic medium, maintaining a removal efficiency above 40%. This study contributed to the evaluation of the removal of a micropollutant commonly found in aqueous media, contributing to the development of strategies to mitigate human exposure to endocrine disrupting agents. Instituição: Universidade do Estado do Rio de Janeiro Tipo do documento: Dissertação 2025-08-28T00:00:00Z