TEDE Coleção: Programa de Pós-Graduação em Química Aplicada

Atividade antioxidante de 2,3-Dihidro-1H-perimidinas intetizadas via reação de condensação do 1,8-Diaminonaftaleno e aldeídos, catalizadas por CuFe2O4 nanoparticulado

2024-12-17T11:46:05Z

Título: Atividade antioxidante de 2,3-Dihidro-1H-perimidinas intetizadas via reação de condensação do 1,8-Diaminonaftaleno e aldeídos, catalizadas por CuFe2O4 nanoparticulado Autor: Siqueira, Cássio Primeiro orientador: Botteselle, Giancarlo Di Vaccari Abstract: Molecular hybridization is the concept employed in the design of new drugs by combining two molecules that already exhibit biological activity to enhance their response. In this regard, perimidines are a class of compounds that have been extensively studied due to their pharmacological properties, including their well-known antioxidant and anti-inflammatory potential. Moreover, the drug probucol was marketed in the 90s as a medication for controlling atherosclerosis precisely because of its antioxidant and anti-inflammatory activity, which resulted in mechanisms of action in the body combating the formation of plaques in blood vessels. Hence, a probucol-perimidine hybrid was proposed as a molecule with potentiated biological activities. Therefore, this study presents the use of the condensation methodology of 1,8-diaminonaphthalene with aldehyde for the synthesis of the molecular hybrid applying copper ferrite (CuFe2O4) nano as a magnetic and nanostructured catalyst, seeking a synthesis less harmful to the environment in line with the principles of Green Chemistry. In addition to the synthesis of the probucol-perimidine hybrid, a systematic study was conducted for the synthesis of other perimidines with diversified structures, obtaining yields of 79-99%. Subsequently, the antioxidant activity of the synthesized compounds was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) free radical methodology, first at concentrations of 500, 250, 125, and 62.5 µmol L⁻¹ with a reaction time of 30 min, and later at concentrations of 100, 50, 25, 12.5, and 6.25 µmol L⁻¹ at time intervals of 15, 5, and 1 min. The best concentration determined for the entire series of perimidines being 50 µmol L-1 in 5 min. By calculating the IC50, it was possible to observe that all proposed molecules presented results better or equivalent to the positive control of trolox, with the most active perimidine having an IC50 of 10.29 µmol L-1. Therefore, it is observed that CuFe2O4 nano demonstrated potential as a catalyst in the synthesis of perimidines and the molecular hybrid, and these synthesized compounds exhibit higher than trolox antioxidant activity. Instituição: Universidade Estadual do Centro-Oeste Tipo do documento: Dissertação

DESENVOLVIMENTO DE MÉTODO ANALÍTICO PARA DETERMINAÇÃO DE RESÍDUOS DE AGROTÓXICOS EM PRÓPOLIS

2024-09-04T12:57:02Z

Título: DESENVOLVIMENTO DE MÉTODO ANALÍTICO PARA DETERMINAÇÃO DE RESÍDUOS DE AGROTÓXICOS EM PRÓPOLIS Autor: Silva, Midiã Zviegicoski da Primeiro orientador: Torres, Yohandra Reyes Abstract: Currently, there is great concern regarding the presence of pesticide residues in bees and apiculture products. Consequently, methods of analysis are being developed to investigate these unwanted contaminants. This study aimed to develop and validate an analytical method for determining pesticide residues in propolis using the QuEChERS sample preparation method and determination by ultra-high performance liquid chromatography coupled with tandem mass spectrometry for detecting the pesticides atrazine, diflubenzuron, imidacloprid, and pyraclostrobin. The QuEChERS method involves an extraction step with acetonitrile, followed by partitioning with magnesium sulfate and sodium chloride salts and simultaneous clean up and drying using d-SPE with PSA and anhydrous magnesium sulfate. The developed method was validated by evaluating the parameters selectivity, matrix effect, linearity, limit of detection, limit of quantification, accuracy and precision. The tests carried out were promising for the desired purpose. The working linear range was obtained in the propolis matrix and was 10 to 100 μg.L-1 for all analytes except for diflubenzuron, with coefficients of determination above 0.99 for atrazine, imidacloprid and pyraclostrobin. Linear regression analysis and the F-test for lack of fit indicated that the linear model is suitable for determining these analytes in the presence of the matrix. Detection limits ranged from 71.6 μg/kg to 465.2 μg/kg and quantification limits ranged from 217.2 μg/kg to 1410.8 μg/kg.Recovery assays were evaluated at three fortification levels, with accuracy between 43 and 101% and intermediate precision and repeatability <20% for most analytes. With the significant increase in the use of propolis, monitoring pesticide residues is becoming increasingly important. Its contamination is a growing concern due to potential impacts on human health and the environment. Instituição: Universidade Estadual do Centro-Oeste Tipo do documento: Dissertação

PRODUÇÃO DE ANTIOXIDANTE PARA O BIODIESEL A PARTIR DA CASCA DE SEMENTE DE HB

2024-06-24T15:11:56Z

Título: PRODUÇÃO DE ANTIOXIDANTE PARA O BIODIESEL A PARTIR DA CASCA DE SEMENTE DE HB Autor: OLEINIK, GIOVANNA Primeiro orientador: Gallina, André Lazarin Abstract: Research into biofuels as alternatives to fossil fuels has been expanding on the global energy scene, as they present environmental and economic advantages. Among biofuels, biodiesel is a viable alternative to petroleum diesel, since its use contributes to reducing the emission of greenhouse gas pollutants, in addition to being biodegradable and presenting commercial and economic advantages. However, biodiesel, as it is obtained from oils and fats that have unsaturated fatty acids in their composition, has low oxidation stability, which causes financial losses in the transport, storage and consumption stages of this biofuel. Therefore, it is mandatory to add antioxidants to biodiesel, aiming to increase its oxidation stability. The HB seed shell is a co-product of a raw material widely produced and sold in Brazil, but which does not yet have a profitable destination. Therefore, the objective of this work was to produce acidic, basic and neutral extracts from HB seed shells to be used as antioxidant additives to soybean biodiesel. To analyze the antioxidant activity of the extracts, the DPPH (2,2-diphenyl-1- picrylhydrazyl) free radical capture test was used. Furthermore, in the work the quantification of phenolic compounds was carried out in the extracts using the Folin Ciocalteau method, and their identification by liquid chromatography (UHPLC). The extracts were added to biodiesel in the biodiesel production or washing stages, by two different methods, mechanical agitation and ultrasound. To analyze the oxidation stability of control biodiesel and biodiesel with the addition of antioxidant extracts, the Rancimat 873 device was used to obtain and compare their induction time (IT). Based on the results, the acid extract produced with HB seed shell in its optimized conditions of 60 min extraction time and 106 g.L-1 concentration and incorporated by mechanical agitation was able to increase the induction time of soy biodiesel when used in combination with 100 ppm TBHQ from 3.65 + 0.12 hours (control biodiesel without added antioxidants) to 16.29 + 0.14 hours. This same extract reached 79.664% antioxidant activity by the DPPH free radical capture test, 761.15 + 116.23 mg EAG.100g-1 of phenolic compounds, with ellagic acid and caffeic acid as the main compounds found in the extract. Furthermore, soybean biodiesel plus acid extract in the washing stage by mechanical agitation presented physicochemical characterization results in accordance with ANP reference values, with the visual appearance of a transparent biodiesel free of impurities, with 882 + 0.2 kg.m³ specific mass at 20 °C, 123 + 1.0 °C flash point, and conductivity of 341 + 10.0 pS/m. Therefore, it is considered that the acid extract produced with HB seed hulls is viable for increasing the oxidation stability of soybean biodiesel. Instituição: Universidade Estadual do Centro-Oeste Tipo do documento: Dissertação

SÍNTESE, CARACTERIZAÇÃO E POSSÍVEIS APLICAÇÕES DE COMPÓSITOS DE α-MoO3 EM MATRIZES POLIMÉRICAS DE POLIANILINA E POLIPIRROL

2024-06-21T18:54:16Z

Título: SÍNTESE, CARACTERIZAÇÃO E POSSÍVEIS APLICAÇÕES DE COMPÓSITOS DE α-MoO3 EM MATRIZES POLIMÉRICAS DE POLIANILINA E POLIPIRROL Autor: SANTA MARIA, ARTHUR LEONHARDT Primeiro orientador: Castro, Eryza Guimarães de Abstract: The focus of this work was to obtain composites of Polyaniline (Pani) and Polypyrrole (Ppy) modified with α-MoO3, characterize and study possible fields of application of these materials in degradation photocatalysis and their capacitance. The oxide was synthesized via reflux in an acidic envirorment, thus eliminating the calcination step required in the usual obtaining routes. 3 oxide composites with Pani matrix were obtained, varying the polymerization time and 3 composites with PPy matrix, varying the oxide concentration. The materials were characterized via SEM, FTIR, EDS, XRD and zeta potential. For the oxide, the SEM shows a lamellar structure in the order of nanometers wide, the FTIR shows the characteristic bands of the α phase, as well as the XRD, the EDS shows only the presence of Molybdenum oxide without the presence of contaminants and the potential zeta has a negative surface charge. For Pani, the SEM and XRD indicate an excellent assimilation of the charge in the polymer after 24 hours of polymerization, a good assimilation with little charge on the surface after 5 hours and a large amount of charge on the surface after 40 minutes of polymerization. The FTIR presents the characteristic bands of Pani without major changes in the band region caused by the oxide. The EDS shows the presence of carbon and nitrogen in the Pani structure, chlorine that functions as a counter-ion and oxygen and sulfur from the polymerization process. Pani's zeta potential is positive. For PPy, SEM and XRD demonstrate that the polymer structure has many voids within the network and that it is in these voids that the oxide enters, not being completely internalized by the polymer. The FTIR shows the characteristic bands of PPy, without major changes due to the oxide, and the EDS shows only the carbon and nitrogen of the structure, as well as chlorine, sulfur and oxygen from the polymerization process. In the degradation photocatalysis, the oxide did not show any degradation of the methyl orange dye (MO), Pani only adsorbed the MO, and the adsorption limit was then calculated at 167.55 mg/g of polyaniline and adsorption rate calculated at 0 .84mg per gram of polyaniline. Pani's composites did not adsorb the dye, but degraded it through catalysis, with the worst result being the composite with the most oxide on the surface. In the photocatalysis of methylene blue (MB), the composites and the polymer did not react, while the oxide degraded it by photocatalysis. In electrochemical studies, the presence of oxide in the composites promoted an improvement in the electrode current response, with the composite presenting the best results in cathodic and anodic peak intensity, as well as the highest calculated capacitance, both for Pani and PPy. Instituição: Universidade Estadual do Centro-Oeste Tipo do documento: Dissertação