Doutorado em Química
URI Permanente para esta coleção
Nível: início
Ano de início: 2014
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=956/a>
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- ItemSíntese e caracterização de complexos de cobalto com potencial para investigação da tautomeria de valência(Universidade Federal do Espírito Santo, 2024-08-06) Pavan, Jamile Rocha; Ribeiro, Marcos Antônio; https://orcid.org/0000-0002-9350-6419; Simões, Tatiana Renata Gomes; Cassaro, Rafael Alves Allão; Franco, Maurício Portiolli; Dalmaschio, Cleocir JoséSystems capable of switching between two or more different electronic states as a result of external stimuli are of great interest for the development of materials with specific properties that can be used in the construction of molecular electronic devices. In this context, bistable compounds that exhibit valence tautomerism (VT) – a reversible intramolecular electron transfer phenomenon – stand out. Among these compounds, cobalt o-dioxolene derivatives have been widely investigated, where electron transfer occurs from the catecholate ligand to the low-spin cobalt(III) ion, forming a high-spin cobalt(II) ion coordinated to a paramagnetic semiquinonate ligand. In light of this, the objective of this research was to synthesize new dinuclear cobalt compounds containing tetradentate nitrogenous ligands, such as N,N’-bis(2-pyridylmethyl)-1,2-diaminoethane (py2en), N,N’-bis(2-pyridylmethyl)-1,3 diaminopropane (1,3-py2pn), and N,N’-bis(2-pyridylmethyl)-1,2-iaminopropane (1,2py2pn) in order to investigate the VT phenomenon. To this end, in addition to the tetradentate nitrogenous ligands, redox-active ligands 2,5-dihydroxy-1,4 benzoquinone (DHBQH2) and 3,3,3',3'-tetramethyl-1,1'-spiro-bis-indane-5,5',6,6' tetrol (spiroH4) were also used. The nitrogenous ligands py2en, 1,3-py2pn, 1,2-py2pn, and the redox-active ligand DHBQH2 were synthesized and characterized by infrared (IR) spectroscopy, mass spectrometry (MS), and proton nuclear magnetic resonance (1H NMR). The synthesis and characterization of two compounds with nitrogenous ligands (1,3-py2pn or py2en) and the DHBQH2 ligand revealed, through IR and X-ray diffraction analyses, the formation of mononuclear cobalt(III) systems, [Co(DHBQ)(1,3-py2pn)]PF6 and [Co(DHBQ)(py2en)]BF4, instead of the proposed dinuclear compound. For the compounds synthesized from the spiroH4 ligand, characterization by IR, UV-vis, electrical conductivity, and X-ray diffraction on single crystal samples indicated the formation of the suggested dinuclear systems. In addition to the intended compounds, two new cobalt compounds were synthesized and characterized: [Co(bpy)(1,3-py2pn)](BF4)3 and [Co(phen)3](NO3)2·2H2O. Finally, the synthesis of new cobalt-o-dioxolene systems in this study offers a significant contribution to future studies of the VT phenomenon, standing out as promising models to investigate VT in both mononuclear and dinuclear compounds.
- ItemAvaliação da qualidade de águas superficiais: uma abordagem local com proposta de mitigação por adsorção em fase sólida(Universidade Federal do Espírito Santo, 2024-12-17) Rocha, Ana Kelly Simões; Costa, Vinicius Câmara; Lima, Maria Tereza Weitzel Dias Carneiro de; https://orcid.org/0000-0002-8731-5093; Rosa, Thalles Ramon; Costa, Eline Nayara Dantas da; Costa, José Arnaldo Santana; Athayde, Geisamanda Pedrini BrandãoThe assessment of surface water quality through continuous monitoring has received increased attention in recent years due to the increasing degradation of aquatic environments. This monitoring is essential to support Contaminated Area Management (CAM) studies, which include important steps such as the preliminary and detailed assessment of aquatic environments. The deltaic region of the Doce River, a floodplain highly vulnerable to contamination, is affected by mining, agricultural and industrial activities, and possibly by the effects of the Fundão dam collapse in 2015. Thus, the city of Degredo, which belongs to the deltaic region, was addressed in a specific case study, which identified high concentrations of Al, Ba, B, Co, Fe, P, Mn, Ni and Zn in the waters of points P1 and P3, above the CONAMA 357/2005 and IRMA legislation, constituting Potentially Toxic Elements (PTEs). A simulated Human Health Risk Assessment (HHRA) at this site ranged from "insignificant" to "low", with water ingestion as the main route of exposure. In addition, analyses showed that contamination levels increased after the dam breach (IPTTh between 0.40 and 23.73), contrary to the expected trend. The adsorption process was used as an alternative for the remediation of water contaminated by EPTs, using the CA-CaCO3 adsorbent, synthesised by dispersing CaCO3 on a porous carbon support derived from biomass. This material contained 12 wt% of nanocrystalline CaCO3 particles. The adsorbent and pure CA showed high efficiency, removing 99.9% of Fe2+, Mn2+, Cd2+, Ni2+, Zn2+ and Pb2+ ions in 20 min under optimised conditions (pH = 6.00 and adsorbent mass = 100 mg). Structural and chemical analyses (XRD, TG, SEM-EDX, mapping and ICP-OES) of CA and CA-CaCO3 helped to understand the structural and chemical characteristics of these materials, while kinetic and isothermal analyses showed that the process occurs by chemisorption. Thus, this work is linked to concepts of risk management, sustainability and circular economy, and provides an efficient and cost-effective alternative for the remediation of water contaminated by EPTs.
- ItemIdentificação da mudança no perfil químico do Coffea arabica(Universidade Federal do Espírito Santo, 2025-02-19) Simmer, Marinalva Maria Bratz; Oliveira, Emanuele Catarina da Silva ; https://orcid.org/0000-0003-0699-6104; http://lattes.cnpq.br/1715851915787164; https://orcid.org/0000-0003-1827-6251; http://lattes.cnpq.br/2232090056040830; Berilli, Savio da Silva ; https://orcid.org/0000-0003-0554-8756; http://lattes.cnpq.br/1703547133505721; Aquije, Gloria Maria de Farias Viegas ; https://orcid.org/0000-0002-8810-7253; http://lattes.cnpq.br/1444372722806046; Figueiras, Paulo Roberto ; https://orcid.org/0000-0003-2617-1601; http://lattes.cnpq.br/1907915547207861The sensory quality of coffee is largely influenced by intrinsic factors, such as species, genetics, and maturation stage, as well as extrinsic factors, including edaphoclimatic conditions and post-harvest processing methods. Climatic variations throughout the physiological cycle, such as temperature, solar radiation, and precipitation, can significantly impact the chemical composition and, consequently, the sensory profile of coffee. Non-volatile compounds, essential for primary and secondary metabolism, are directly linked to the formation of volatile compounds responsible for the beverage’s aroma and flavor. In this study, chemical and sensory variations were investigated over two years (2020 and 2021) using analytical techniques such as mid-infrared (MIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS). Additionally, five post-harvest processing methods were evaluated to understand how these factors interact under different climatic conditions. GC-MS results revealed effective discrimination between harvest periods. In September, a higher abundance of acids, sulfur compounds, alcohols, aldehydes, thiazoles, esters, pyrazines, diacetones, and pyrans was observed. In contrast, coffees harvested in November showed a higher concentration of furans, thiophenes, thiols, pyrroles, and phenols. MIR analysis revealed low chemical separation between harvests within the same year (2021). However, certain spectral regions, such as 3200 cm−1, associated with intermolecular hydrogen bonding interactions, and the 1455 cm−1 range, previously linked to functional group vibrations in lipids, caffeine, and chlorogenic acids, were crucial in identifying separation trends between harvests. On the other hand, sensory evaluation showed more pronounced differences, particularly in coffees subjected to induced fermentations. Partial Least Squares Discriminant Analysis (PLS-DA) demonstrated high efficiency in classifying samples, achieving excellent performance in calibration and validation. These findings reinforce the influence of annual climatic conditions on the chemical and sensory composition of coffee. In particular, climate variations appear to have impacted the metabolism of key compounds responsible for modifying the beverage’s flavor and aroma. This study contributes to the understanding of the effects of environmental conditions and processing methods on coffee quality, aiding in the optimization of agricultural and post-harvest practices.
- ItemMetal-organic frameworks : da produção de tecidos funcionais ao Ensino de Química(Universidade Federal do Espírito Santo, 2024-08-30) Almeida, Caroline Batistin da Cruz; Moura, Paulo Rogério Garcez de ; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Luz, Priscilla Paiva ; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; Alves Junior, Severino; https://orcid.org/; http://lattes.cnpq.br/; Pimenta, Patrícia Figueiredo Santos ; https://orcid.org/; http://lattes.cnpq.br/; Tavares, Mari Inez ; https://orcid.org/; http://lattes.cnpq.br/; Dalmaschio, Cleocir José ; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/Glyphosate (GLY) is an organophosphate pesticide widely used in agriculture as a non selective, broad-spectrum herbicide. It is the most widely sold pesticide in Brazil and worldwide and is considered potentially carcinogenic to humans according to the World Health Organization. Porous materials have been tested for the adsorption of this compound in aqueous media, with zirconium-based MOFs (ZrMOFs) being the materials with the best reported performance. This research evaluated the adsorption performance of GLY by ZrMOFs not yet investigated and produced cellulose composites functionalized with MOFs for the same application. The MOFs MOF-808, UiO-66 and UiO-66(NH2) were synthesized and characterized by XRD, TGA, DTA, N2 adsorption, DLS and pcz. Adsorption tests were performed in batch mode and PPO, PSO and Weber-Moris kinetic models were applied to the results. The adsorption equilibrium was investigated by the Langmuir and Freundlich models. MOF-808 synthesized in water reached the maximum GLY adsorption capacity of 277.0 mg g-1 and MOF-808 synthesized in DMF obtained 273.2 mg g-1, however, with better kinetic performance removing approximately 70% of GLY in solution in 10 minutes of contact and 99.5% in 5h. The PSO model best fitted the kinetic results indicating great availability of active sites for adsorption in the materials and the chemical nature of GLY adsorption in the material. The Langmuir model confirms this character indicating monolayer adsorption and the same interaction energy in the active sites. Cellulosic fibers functionalized with MOF-808 via in situ and ex situ methods were successfully obtained and showed good GLY adsorption performance, removing 99% of GLY in 3 hours of contact with a 0.1 mM solution of the herbicide. These fibers have potential applications for filters and personal protective clothing. Based on the theoretical framework involving the results obtained, a teaching plan on “MOFs for water decontamination” was developed, aimed at teaching Chemistry at the high school level. Problem-based experimental activities were applied to develop skills for the New High School Training Itinerary through the theme. It was observed that skills in the areas of scientific investigation, creative processes and sociocultural mediation were developed throughout the activities, and the theme proved to be an important strategy for teaching various objects of knowledge in the Chemistry curriculum, such as bonding theories, mixture separation techniques, acid-base theories, formulas, properties and reactions of organic compounds
- ItemSíntese e caracterização de MOFs e seus compósitos utilizados na modificação de eletrodos de carbono aplicados como sensores eletroquímicos(Universidade Federal do Espírito Santo, 2024-08-08) Fonseca, Ramon Raoni Ferreira da; Ferreira, Rafael de Queiroz; https://orcid.org/0000-0002-5190-8508; Luz, Priscilla Paiva; https://orcid.org/0000-0002-9460-546X; https://orcid.org/0000-0002-0603-9999; Rosa, Thalles Ramon; Caliman, Cristiano; Ribeiro, Josimar; Ribeiro, Marcos AntônioThe metal-organic frameworks (MOFs) MIL-53(Fe), MIL-88b-NH2(Fe), MIL-100(Fe) and MIL-82(Fe) were synthesized from the solvothermal reaction between a Fe salt and na acid ligand (benzene-1,4-dicarboxylic acid, 2-amino-benzene-1,4-dicarboxylic acid, benzene-1,3,5-tricarboxylic acid, or benzene-1,2,4,5-tetracarboxylic acid). All the materials obtained were characterized using physicochemical techniques. The electrochemical techniques showed that MIL-88b-NH2(Fe) had the most promising results for developing an electroanalytical methodology to detect and quantify Cu2+ in ethanol fuel. The presence of Cu2+ in ethanol fuel represents a problem in terms of quality, leading to malfunctioning automotive engines. Therefore, this study uses a FeIII-organic network to develop an innovative electrochemical sensor. Subsequently, the modified carbon paste selected to analyze Cu2+ in ethanol fuel was MIL-88b NH2(Fe) based on the results obtained from cyclic voltammetry and electrochemical impedance spectroscopy. Subsequently, square-wave anodic stripping voltammetry parameters were optimized using a design of experiments approach. The analytical signal of the electrode exhibited good stability (relative standard deviation = 5.2%). Besides, the correlation coefficient (r) and coefficient of determination (R²) calculated in the calibration curve were 0.9993 and 99.85%, respectively, indicating a good fit of the linear model to the experimental data. The limit of detection obtained from the linear equation was 2.0 × 10−8 mol L−1. Finally, in the recovery test using spiked samples of ethanol fuel, the obtained values were 83 and 96%, indicating the absence of matrix effects. It was shown that the MIL-88b-NH2(Fe) modified carbon paste electrode is a suitable sensor for assessing Cu2+ contamination in ethanol fuel under and above the limit permitted by Brazilian legislation.