http://bdtd.uftm.edu.br/handle/tede/521 Sun, 26 Apr 2026 15:36:35 GMT 2026-04-26T15:36:35Z http://bdtd.uftm.edu.br/handle/123456789/1961 Título: Produção e caracterização de carvão ativado proveniente de cascas de grãos de café e de cascas de grãos de girassol Abstract: The study of the use of biomass and lignocellulosic waste in the production of activated carbon has shown positive results for the development of new technologies that are used to collaborate with processes that involve the use of those adsorbents. Lignocellulosic residues from the cultivation of different biomasses are materials that are produced on a large scale and, if disposed of inappropriately in the environment, can cause environmental problems. Any carbonaceous material can be used to produce activated carbon, as long as it has a low content of inorganic components, low cost, high availability, does not suffer degradation during storage, is easy to activate and produces good adsorbents. The aim of this work is to produce and characterize activated carbon from coffee seed husks and sunflower seed husks, residual biomass found on a large scale in Brazil due to the production of coffee and sunflower oil. The method used consists of previously carbonizing the biomass at 700°C under an inert atmosphere of nitrogen (N2), followed by an activation process using potassium hydroxide (KOH) in a dry method. The activation parameters such as the activation temperature (600, 700 and 800°C) and the impregnation mass ratio (1:1, 1:2 and 1:4) were evaluated during the production of the adsorbents. The activated carbons produced were characterized using techniques such as: Fourier transform infrared spectroscopy (FT-IR), surface area analysis, average pore volume and pore distribution based on BET adsorption-desorption isotherms and scanning electron microscopy (SEM). The microscopy analyses indicated the development of a porous structure predominantly formed by mesopores and micropores, with a high carbon and oxygen content in the composition of the adsorbents. The activated carbon sample that showed the best results was the one produced from sunflower seed husks, activated at 700°C with an impregnation ratio of 1:4 (coal:KOH), showing a surface area of 1326,54 m2.g-1, an average pore volume of 0,7947 cm3.g-1 and an average pore diameter of 2.34 nm. Based on the results obtained, it is possible to state that both biomasses studied have favorable chemical and structural characteristics for the production of activated carbon, and also that the activation method used led to the development of a porous structure with a high surface area value when compared to other materials in the literature. Tipo: Dissertação Thu, 12 Sep 2024 00:00:00 GMT http://bdtd.uftm.edu.br/handle/123456789/1961 2024-09-12T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/1948 Título: Filmes nanoestruturados contendo óxido de grafeno reduzido e óxido de tungstênio: estudo em dispositivos superca Abstract: The research dedicated to the development of new nanocomposites plays a crucial role in the quest for supercapacitors with higher energy storage capacity. In this study, strategies employing nanostructured films through the Layer-by-Layer (LbL) self-assembly technique were employed. These films consist of the incorporation of tungsten oxide (WO3) and reduced graphene oxide (rGO) nanostructures combined with Poly(amidoamine) (PAMAM) on a glass substrate coated with ITO (indium tin oxide) for supercapacitor study. The growth of the films was monitored by (UV-VIS) spectroscopy, while images from atomic force microscopy (AFM) confirmed the formation of self-assembled PAMAM/GO-WO3 nanostructures. Cyclic voltammetry (CV) and galvanostatic charge-discharge measurements revealed the electrocapacitive characteristics of the PAMAM/GO LbL films, with capacitance values of 7.08 mF/cm² and 27.70 F/g, and values of 6.8 mF/cm² and 73.58 F/g for the PAMAM/GO-WO3 LbL films, respectively, at a current of 1.1x10-5 A and a scan rate of 100 mV/s. All films showed high capacitive retention performance, with no capacitance loss over 2000 charge-discharge cycles. These results demonstrate that the investigated films have suitable properties to be explored in nanostructured systems for energy storage. Tipo: Dissertação Wed, 17 Jul 2024 00:00:00 GMT http://bdtd.uftm.edu.br/handle/123456789/1948 2024-07-17T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/1947 Título: Investigação das propriedades ópticas de íons de Mn2+ com nanocristais de CsPbI3 Abstract: The present work aimed to synthesize and characterize the optical, structural and electronic properties of Mn2+ ions and Perovskite - CsPbI3 nanocrystals in a glass matrix. To analyze the optical properties of nanocrystals, UV-Vis-NIR Optical Absorption Spectroscopy and Photoluminescence Spectroscopy experiments were carried out. Structural characterizations were carried out using X-ray Diffraction and Transmission Electron Microscopy. As results, experimental evidence was observed for energy transfer from CsPbI3 nanocrystals, synthesized by the fusion method, to Mn2+ ions embedded in glassy systems (SBNAPC: SiO2-B2O3–NaI–Al2O3–PbI2–Cs2CO3). The transfer of radiative and non-radiative energy between the Perovskite nanocrystals and the levels of Mn2+ ions were observed in the photoluminescence spectra. It is believed that these results can inspire further investigation of similar systems to enable possible laser devices or applications. Furthermore, a glass matrix analysis strategy protects the nanocrystals from chemical attack in a hostile environment, ensuring long-term stability, as they are easily oxidized or inactivated in the presence of oxygen, humidity or light irradiation. Tipo: Dissertação Tue, 06 Aug 2024 00:00:00 GMT http://bdtd.uftm.edu.br/handle/123456789/1947 2024-08-06T00:00:00Z http://bdtd.uftm.edu.br/handle/123456789/1823 Título: Complexos de rênio e tecnécio com derivados do Megazol: potenciais agentes multifuncionais para o tratamento e diagnóstico da doença de Chagas Abstract: Chagas disease (CD) is a neglected disease that affects mainly Latin American People. The treatment and diagnosis, particularly during the chronic phase, are ineffective due to the lack of symptoms and low parasitemia. For this reason, CD requires not only new trypanocidal agents but also more efficient diagnostic techniques. For improving such problems, new rhenium complexes (natural isotope) can be employed in Chagas chemotherapy, while analogous 99mTc complexes can be used to diagnose/monitor the disease while the combination of them can lead to the development of a theranostic device (therapy + diagnosis). Therefore, the main objective of the present work was the synthesis, characterization and evaluation of the trypanocidal activity of complexes containing the fac-{185/187Re(CO)3} fragment with derivatives from the trypanocidal drug known as Megazol. The peripheral structure of Megazol (LH,H) was modified to obtain the compounds LR,R (R = H, Me and R= Me, Me), which were used in the syntheses of complexes of composition [ReBr(CO)3LR1,R2]. The techniques employed in the structural determination and study the chemical properties of compounds were: elemental analysis, absorption spectroscopies in the IR and UV-vis region, NMR (1H and 13C), HR-ESI-MS, HPLC/UPLC, single-crystal XRD and DFT methods. The trypanocidal activity of the compounds was evaluated in vitro against the intracellular form of T. cruzi. The results showed that the ligand complexation to the {Re(CO)3}+ core does not significantly change the trypanocidal activity and, with exception of the [ReBr(CO)3LMe,Me] complex, all compounds exhibited SI better than the standard drug, benznidazol (Bz). In addition, the interaction of megazol and its Re complex was evaluated, by both experimental and computational methods, with T. cruzi Old Yellow Enzyme (TcOYE) protein. The data showed that megazol as well as the metallic complex presented higher affinity for TcOYE than Bz. Finally, it was possible to affirm that the labelling of megazol with 99mTc was carried out successfully, although the results have indicated the Re complexes, used as standard, were not homologous with the 99mTc complexes, probably, due to a charge difference between them. Nevertheless, the combination of the Re and 99mTc compounds studied here represents an important step towards the development of a theranostic device for CD. Tipo: Tese Fri, 28 May 2021 00:00:00 GMT http://bdtd.uftm.edu.br/handle/123456789/1823 2021-05-28T00:00:00Z