Dissertation/Thèse

2022
Thèses
1
  • PRISCILA DE ALMEIDA SILVA
  • KETALIZATION OF ETHYL LEVULINATE FOR THE PRODUCTION OF POTENTIAL BUILDING BLOCKS IN ORGANIC SYNTHESIS

  • Leader : RAQUEL VIEIRA MAMBRINI
  • MEMBRES DE LA BANQUE :
  • ADRIANA AKEMI OKUMA
  • CLEVERSON FERNANDO GARCIA
  • EUDES LORENCON
  • Data: 14 juil. 2022


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  • The intensification of environmental pollution caused by the constant consumption of products of fossil origin has been driving the development of substitutes from sustainable sources, such as those derived from lignocellulosic biomass. The objective of the present work was to synthesize an organic compound with the potential to be used as a building block in organic syntheses from the biomass derivative of ethyl levulinate through the ketalization reaction using the polyalcohol pentaerythritol in the presence of two types of catalysts, carboxylate of mesoporous niobium (CNbM), developed by our research group and the commercial cationic resin Amberlyst®15.

    The development and characterization of CNbM was the object of study of our research group. Since this material proved to be very promising as a catalyst, it was chosen for testing in ketalization reactions within the scope of this dissertation. The cationic resin (Amberlyst®15) was used as a model catalyst since the literature correlates its use with high conversion rates and selectivity for the formation of the ketal group; with this, the results obtained between the two catalysts already described will be compared.
    The present work developed a methodology for the synthesis of the CNbM catalyst. Through the characterization techniques by absorption spectroscopy in the infrared region, thermogravimetry, and X-ray diffraction, it was possible to observe evidence of the occurrence of coordination of the ligand to the metal and consequent obtaining material, based on literature data. The acidity measurement of the niobium-based material was equal to 0.94 mmolH+ gsol-1 which, compared to Amberlyst®15 (4.42 mmolH+ g-solid-1) appears to be of a more moderate nature.
    The ketalization reaction between ethyl levulinate ester and pentaerythritol alcohol took place in a Dean Stark system and according to the characterization analysis by infrared absorption spectroscopy and mass spectrometry with electrospray ionization, the ketal of interest was formed.

2
  • MARIANA DE AGUILAR SANTOS
  • EVALUATION OF CHEMICAL AND BIOLOGICAL ATTRIBUTES OF CONSTRUCTED NICHES USING IRON ORE TAILING: an alternative for the revitalization of degraded areas.

  • Leader : ANDREA RODRIGUES MARQUES
  • MEMBRES DE LA BANQUE :
  • ANDREA RODRIGUES MARQUES
  • ANGELA DE MELLO FERREIRA
  • FABIANA DA CONCEICAO PEREIRA TIAGO
  • FERNANDA BADOTTI
  • PATRICIA SUELI DE REZENDE
  • VALERIA CRISTINA PALMEIRA ZAGO
  • Data: 25 août 2022

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  • The iron ore extraction industry is one of the important sectors for the Brazilian economy, especially in the Quadrilátero Ferrífero region, Minas Gerais. This activity generates a significant environmental impact on the Campo Rupestre ecosystem and the disposal of the generated tailings is a recurring socio-environmental problem, especially after the failure of two tailings dams in the state. The use of Constructed Niche (CN) is a recently presented technique, which has as its constituent iron ore tailings, topsoil, and binder. The application of the NC technique aims to mimic pre-existing ecological niches in areas degraded by mining activities, by bringing biotic components from the place of interest. This study aimed to characterize the topsoil of a non-degraded area of CR in terms of chemical and mineralogical composition and fertility; to evaluate the effects of new CN constituents (such as bentonite clay and fungal mycelium biocomposite) on its mechanical property and on its biological attributes, such as: microbial biomass carbon (MBC), basal respiration (BR) and metabolic quotient (qCO2 ) and observe the presence of photobiont organisms during the incubation period from 7 and 180 days. The CNs were made by adding different proportions of topsoil from CR of the Serra da Piedade, iron ore tailings (30%), cement (5%), clay (10%) and biocomposite (10%). XRD and XRF analyzes of topsoil identified minerals such as hematite, quartz and goethite and high proportions of Fe oxide and silicon dioxide. Fertility analyzes showed low concentration of nutrients, including Ca, K, P, and CEC (cation exchange capacity), as well as low content of organic matter, C, N and acidic pH. These observed features are typical of ferruginous CR topsoil. The new binders used in the manufacture of CNs did not provide strength to the material, making it necessary to test new proportions in future studies. Only the cement conferred resistance to the CN, as it is a good binder, promoting the cohesion of the constituent particles of the module (topsoil + tailings). The MBC between the controls and the treatments showed no significant difference when compared between the two incubation times, except for the NC containing the biocomposite. The BR results were low for the controls and topsoil + tailings, but in the treatments containing clay and biocomposite the results were significant. The growth of photobionts such as bryophyte gametophytes, pteridophyte prothallus, angiosperm seedlings and algae were observed in topsoil and topsoil+tailings. For CNs containing cement and clay there was the appearance of fungi during the incubation period and, in the time of 180 days, in addition to fungi, the development of angiosperm was observed on the surface of the CN containing the biocomposite. The analyzes of the present study indicate that the CN made with biocomposite has greater potential to act as life development stimulators.

3
  • NATÁLIA CRISTINA MORAIS FERNANDES
  • Characterization of chemical products obtained from the lignin degradation by fungi Trametes villosa

  • Leader : FERNANDA BADOTTI
  • MEMBRES DE LA BANQUE :
  • ADRIANA AKEMI OKUMA
  • ANA MARIA DE RESENDE MACHADO
  • ARISTOTELES GOES-NETO
  • FERNANDA BADOTTI
  • Data: 27 sept. 2022

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  • The biological valorization of lignin as a raw material for the production of fuel and and value-added chemical products allows for the implementation of sustainable biorefineries, as it is a renewable input. Lignin is a highly recalcitrant compound found in all types of plants, which is part of the complex known as lignocellulose. The lignocellulose complex is a fibrous matrix formed by cellulose, hemicellulose and lignin. The best known applications are for cellulose and hemicellulose, and lignin presents the greatest challenge from an industrial point of view, due to the need for depolymerization. However, there is great interest in studying the use of lignin, since it has a structure rich in aromatic groups. In nature, the complete degradation of plants is carried out by fungi and bacteria. Currently, several species of fungi with high potential for lignin degradation are known. The process of degradation of plant material is complex, and different microorganisms, enzymes and finely regulated and interconnected metabolic pathways are involved. This work aims to characterize the chemical products formed from the microbiological degradation of lignin. For this, two different sources of lignin were used as substrate, synthetic alkaline lignin and lignin from sugarcane bagasse and subjected to degradation by the fungus Trametes villosa CCMB561. After 10 days of incubation, the supernatant of experiment was collected and analyzed for the presence of chemical compounds. For the characterization of the substances formed during the process of microbiological degradation of lignin, the samples obtained were submitted to analysis of Gas Chromatography - Mass Spectrometry (GC-MS) and Spectrophotometry in the Ultraviolet and visible region (UV-vis). The degradation of lignin by fungi and enzymes are well described in the scientific literature. However, the products derived from the microbiological of lignin degradation are still little know, thus allowing a vast field for study. The prospection of products from the biological degradation of lignin will expand the potential of application of lignin as a matrix of chemical inputs.

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