Mestrado em Química
URI Permanente para esta coleção
Nível: Mestrado Acadêmico
Ano de início: 2006
Conceito atual na CAPES: 5
Ato normativo: Homologação da 85ª Reunião do CTC-ES, Parecer CNE/CES nº 163/2005.
Processo nº 23001.000081/2005-56 do Ministério da Educação.
Publicado no DOU 28/07/2005, seção 1, página 11)
Periodicidade de seleção: Anual
Área(s) de concentração: Química
Url do curso: https://quimica.vitoria.ufes.br/pt-br/pos-graduacao/PPGQ/detalhes-do-curso?id=954
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- ItemUtilização de solventes eutéticos profundos em resinas poliméricas quimicamente recicladas para determinação multielementar(Universidade Federal do Espírito Santo, 2024-10-09) Rasch, Matheus Barbosa; Lima, Maria Tereza Weitzel Dias Carneiro ; https://orcid.org/0000-0002-8731-5093; http://lattes.cnpq.br/; Silva Filho, Eloi Alves da ; https://orcid.org/0000-0002-9306-7882; http://lattes.cnpq.br/; https://orcid.org/0009-0002-4069-6180; http://lattes.cnpq.br/; Souza, Jefferson Rodrigues; https://orcid.org/; http://lattes.cnpq.br/; Dalmaschio, Cleocir José; https://orcid.org/; http://lattes.cnpq.br/The search for greener methodologies has challenged analytical chemists, leading to the development of methods that minimize environmental impact and risks to analysts. Green Analytical Chemistry, composed of 12 principles, has been a guide for these innovations, with recent emphasis on deep eutectic solvents (DES). These mixtures formed by intermolecular interactions provide unique physicochemical properties, such as melting point, viscosity, density and solubility, making them attractive for extractions and solubilizations. Among DES, natural deep eutectic solvents (NADES), composed of substances of primary metabolic origin, are even more sustainable, being formed by compounds with low toxic potential. Despite their advantages, DES are still rarely applied to certain samples, such as polymers, which have been the focus of growing concern due to the presence of microplastics and contamination by trace elements. Given this scenario, this study aims to determine trace elements (Al, Ba, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Sb, Ti and Zn) in chemically recycled polymeric resin, developed in partnership between UFES and Vale, using DES as a greener alternative to conventional methods. Four DES were prepared based on choline chloride and water, combined with malic acid, oxalic acid, phenol and urea, of which three are NADES. The polymeric samples were subjected to ultrasound-assisted extraction (UAE-DES) and analyzed by ICP-MS. The characterization of the DES by FTIR and NMR confirmed their adequate formation, and the Hansen solubility parameters (HSP) were used to understand the solvent-sample interactions - wich allowed the unprecedented determination of the sample’s Hansen solubility parameters itself. The results showed that DES were effective in recovering elements such as antimony (Sb), barium (Ba), and manganese (Mn), although the recovery efficiency varied: Sb was determined in all DES, Ba in NADES, and Mn only in solvents formed with acids. The AGREEprep metric demonstrated the environmental advantage of DES over the traditional microwave-assisted acid decomposition (MW-AD) method, with the highest score of 0.61 for NADES. However, elements such as aluminum (Al) and iron (Fe) showed unsatisfactory recoveries, suggesting the need for method optimization. The use of DES is a viable alternative for the preparation of recycled polymeric samples, with promising results for multielement determination and considerable environmental advantages. Additional adjustments may improve the recoveries of some elements and expand the use of the methodology to other matrices
- ItemReciclagem do cátodo de bateria de íons de lítio do tipo LiFePO4 (LFP) e aplicação do material reciclado como pseudocapacitor(Universidade Federal do Espírito Santo, 2024-07-30) Querubino, Renan Bobbio; Freitas, Marcos Benedito José Geraldo de; https://orcid.org/0000-0003-1521-774X; Machado, Marta Albuquerque; Pietre, Mendelssolm Kister deRecycling lithium-ion batteries (LIBs) is an effective method of solid waste treatment and is crucial for the recovery of scarce, high-value metals that are of great technological importance. In this work, spent LIBs from electric vehicles were recycled through hydrometallurgical and pyrometallurgical processes, utilizing both citric acid and hydrogen peroxide leaching and alkaline leaching. The exhausted cathode material was characterized using X-ray Diffraction (XRD), Raman Spectroscopy, Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), identifying LiFePO4, Fe2O3, and FePO4 as the primary phases in its composition, along with the secondary phases Fe(OH)3 and Fe2(PO4)O. The hydrometallurgical recycling process, performed by acidic leaching of the cathode with 1.0 mol L−1 citric acid and hydrogen peroxide, showed low selectivity for the leaching of lithium and iron. In contrast, alkaline leaching proved to be more effective in recovering lithium and preserving the structural components of the material, such as LiFePO4, while not leaching iron, resulting in a more efficient separation of battery constituents. From the residue of alkaline leaching, lithium ferrite (β-LiFe5O8) was synthesized. Structural and morphological characterizations of lithium ferrite, performed by XRD, Raman Spectroscopy, and SEM, indicated the formation of a disordered crystalline phase with agglomerated grain morphology, with particles of undefined size. The electrochemical evaluation of the recycled material as a pseudocapacitor was promising. The recycled material exhibited a pseudocapacitive profile with a maximum specific capacitance of 7.6 F g−1 and capacitance retention of 82% over 250 cycles, at a charge-discharge current density of 0.7 A g−1. The pseudocapacitive profile of this material included contributions from electric double-layer charge storage and Faradaic processes. This study demonstrates the feasibility of recycling spent lithium-ion battery materials, transforming them into high-value-added materials with promising technological applications, contributing to sustainability and the circular economy.
- ItemBusca de plantas medicinais da Renisus através da triagem virtual para atividade anti-Helicobacter pylori(Universidade Federal do Espírito Santo, 2024-04-26) Mendes, Campili; Kitagawa, Rodrigo Rezende ; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; Beltrame, Flávio Luís ; https://orcid.org/; http://lattes.cnpq.br/; Borges, Warley de Souza ; https://orcid.org/; http://lattes.cnpq.br/Helicobacter pylori (H. pylori) is a Gram-negative bacterium that infects and colonizes the gastric mucosa of around half of the world's population, and its prevalence is higher in developing countries, reaching up to 90%. H. pylori infection triggers a series of diseases ranging from gastritis and ulcers to gastric cancer, which is the fifth most common cancer in humans. The bacterium is considered a group I carcinogen, according to the World Health Organization, and is included in the list of high-priority bacteria in the development of new drugs. In this context, medicinal plants and their phytocompounds are valuable shortcuts for discovering new, safer antibiotics with reduced adverse effects. In this context, the aim of this study was to select species from the National List of Medicinal Plants of Interest to the Unified Health System (Renisus) with potential anti-H. pylori activity, firstly through a bibliographic survey, followed by the creation of a phytochemical database and evaluation in an activity prediction model using PASS (Prediction of Activity Spectra for Substances), Tanimoto Similarity and, finally, in vitro evaluation. Once the species had been selected, the chemical profile was determined by high-resolution mass spectrometry (ESI-FT-ICR/MS - Electrospray Ionization-Fourier Transform Ion Cyclotron Resonance/Mass spectrometry) and liquid chromatography coupled to mass spectrometry (LC-MS - Liquid chromatography-mass spectrometry), and the compounds identified were analyzed by molecular docking in the active site of the bacterial target. After the bibliographic survey, 4 species were selected based on studies against gastritis and ulcers, but without studies against H. pylori, namely: Bauhinia forficata, Jatropha gossypiifolia, Sonalum paniculatum and Vernonia condensata. In the virtual screening, using PASS, the species J. gossypiifolia showed more compounds with the possibility of being active for 02 targets of action: the enzymes urease and fumarate reductase. Tanimoto's similarity analysis used standard inhibitors of these targets, acetohydroxamic acid and licochalcone A, respectively, to which the compounds present in J. gossypiifolia showed better similarity compared to the other species. To validate the virtual screening, in vitro tests were carried out to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts of the 4 selected species, with J. gossypiifolia showing the best results with a MIC of 64 µg/mL and MBC of 128 µg/mL. An in vitro urease inhibition test was also carried out, but none of the species selected showed satisfactory concentration/response activity against the enzyme. Among the compounds suggested by ESI-FT-ICR/MS and LC-MS, C-glucosilated flavonoids such as 3-genistein-8-C-glycoside and derivatives of luteolin and apigenin had the potential to interact with the active site of furamate reductase, hydrogen bonding with Arg404. In addition, 3-genistein-8-C-glucoside and luteolin 7-O-glucoside have five hydrogen bonds with amino acid residues, which is similar to the interaction of the fumaric acid ligand in the enzyme's active site. In view of the above, virtual screening proved to be a valuable tool in this study, and J. gossypiifolia showed promising activity and could represent an alternative source of compounds for treating H. pylori and preventing its harmful effects
- ItemDesenvolvimento de eletrocatalisadores a base de óxidos de Sn, Co e Cu para a eletrorredução de CO2(Universidade Federal do Espírito Santo, 2024-03-04) Garcia, Robson Roella; Ribeiro, Josimar ; https://orcid.org/0000-0002-9544-1647; http://lattes.cnpq.br/1265145498501171; https://orcid.org/0009-0002-2674-6612; http://lattes.cnpq.br/8820348835691850; Ferreira, Rafael de Queiroz ; https://orcid.org/0000-0002-5190-8508; http://lattes.cnpq.br/5053247764430323; Rosa, Thalles Ramon ; https://orcid.org/0000-0001-9913-5885; http://lattes.cnpq.br/2629035369494897The electrochemical reduction of CO2 (RECO2) using electrocatalysts could be an alternative to overcome the problems generated by high CO2 emission rates. To catalyze RECO2 in the formation of other products, there are several metal oxides described in the literature, such as SnO2, Co3O4 and CuO. SnO2, Co3O4 are able to catalyze RECO2 to formate, CuO to reduce CO2 to methane, formate, ethanol and carbon monoxide. The aim of this work was to synthesize electrocatalysts based on pure Sn, Co and Cu oxides supported on Vulcan XC 72 carbon by the simple ion coprecipitation method. In order to characterize the crystal structures of the synthesized materials, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and Raman techniques were used. Initially, the XRD data confirmed the formation of the synthesized oxides. However, the carbon-supported materials did not show any characteristic peaks using this technique, probably due to their amorphous structure. The Raman technique made it possible to identify carbon in the samples supported on Vulcan XC 72 carbon. SEM and MET data made it possible to identify the morphology of the particles. Thus, it was possible to observe the formation of spherical agglomerates with an average size of 11.0 nm for SnO2 and 13.0 nm for SnO2/C. In the case of Co3O4, Co3O4/C, polygonal particles with an octahedral shape were formed with an average size of 15.7 nm for Co3O4 and 20.6 nm for Co3O4/C. For CuO and CuO/C, agglomerates of particles with an average size of 30.0 nm and 40.0 nm were formed. The electrocatalysts were characterized using the cyclic voltammetry (CV) technique. The oxidation and reduction peaks of the oxides were observed at −1.5 V to 1 V (versus Ag/AgCl (KCl 3.0 mol L−1)). Linear scanning voltammetry (LSV) was then used to study the electrochemical behavior of the oxides synthesized in the presence of CO2. VVL showed that the Co and Cu materials presented a higher current in an N2-saturated medium than in a CO2-saturated solution, indicating that there was competition in the hydrogen evolution reactin was favored. Among the materials studied, CuO/C was the electrocatalyst that showed the best current density when saturated with CO2, at a potential of −1.6 V (versus Ag/AgCl (KCl 3.0 mol L−1)). This material was then used in RECO2 using the chronoamperometry technique, applying a fixed potential of −1.6 V (versus Ag/AgCl (KCl 3.0 mol L−1)) for 30 min, in a solution with a constant flow of CO2. Finally, aliquots of this solution were removed and analyzed via nuclear magnetic resonance, which indicated the formation of some products from the reduction of CO2 such as ethane, acetone and acetate. These studies have therefore demonstrated the potential use of electrocatalysts synthesized by simple ion coprecipitation for the electrochemical reduction of CO2
- ItemSíntese De Zeólitas A Partir De Resíduos De Rochas Ornamentais, Modificadas Com Nb2O5/SO42-, E Aplicação Como Catalisador Para Síntese De Biodiesel(Universidade Federal do Espírito Santo, 2024-02-05) Céleri, Eliomar Pivante; Barañano, Audrei Giménez ; https://orcid.org/0000-0002-0174-5202; http://lattes.cnpq.br/6155024776819193; Lacerda Júnior, Valdemar; https://orcid.org/0000-0002-8257-5443; http://lattes.cnpq.br/9819471276433138; https://orcid.org/0000-0003-0398-1687; http://lattes.cnpq.br/7451829765311645; Machado, Marta Albuquerque; https://orcid.org/0000-0001-8335-3351; http://lattes.cnpq.br/5991893415892784; Pinheiro, Patrícia Fontes ; https://orcid.org/0000-0003-4019-5773; http://lattes.cnpq.br/7891884643619330Brazil stands out as a major producer of ornamental rocks, with the state of Espírito Santo making a significant contribution by producing approximately 80% of this type of rock in the country. However, this production generates waste that requires management to mitigate environmental impacts. In this study, ornamental rock waste was used for the first time to synthesize zeolites. The waste consisted of quartz and potassium feldspars, albite, and orthoclase. Due to the mineralogical composition, the alkaline fusion method was employed to destroy the crystalline structure and obtain reactive aluminosilicates for zeolite crystallization. Crystallization took place in polyethylene flasks at 95°C for 48 hours. The results showed that, in just 6 hours of crystallization, LTA zeolites were obtained with over 99% crystallinity. After 48 hours, LTA zeolites were converted into SOD zeolites. The SOD zeolite was modified with sulfated niobium oxide, presenting a surface area of approximately 19 m2 .g-1 , pore volume of 0.076 cm3.g-¹ , and most frequent pore diameter of 3.360 nm, classified as mesoporous. LTA, SOD, and modified SOD zeolites were tested as catalysts for the transesterification of soybean oil and esterification of fatty acids for biodiesel production. Different alcohols (methanol, ethanol, butanol, and isoamyl alcohol) were used for synthesis, varying reaction parameters such as time (2 to 12 hours), temperature (60 to 100°C), and alcohol-to-oil ratio (10:1 to 25:1). Although pure SOD zeolite showed no catalytic activity for biodiesel synthesis from esterification and transesterification reactions, modification with Nb2O5/SO4²- resulted in 12% conversion for biodiesel synthesis by transesterification and 52% by esterification. Among the catalysts studied, the trend for better catalytic activity was observed for Nb2O5/SO4²- > SOD/Nb2O5/SO4²- > Nb2O5 > LTA zeolite > SOD zeolite. Finally, this study demonstrates the feasibility of using ornamental rock waste in zeolite synthesis, paving the way for innovative and sustainable applications.