Carmen Guedes - Profile on Academia.edu (original) (raw)

Papers by Carmen Guedes

Revista Sodebras, Jul 1, 2023

A Edição 211 é relativa ao XLV International SODEBRAS Congress, ocorrido no mês de maio do corren... more A Edição 211 é relativa ao XLV International SODEBRAS Congress, ocorrido no mês de maio do corrente ano. Esse congresso já é tradicional no cenário acadêmico brasileiro e reúne pesquisadores dos diversos setores do saber. O evento acontece de maneira itinerante e neste ano foi realizado em Curitiba-PR. Nesta edição, na busca de contribuir para o desenvolvimento tecnológico e científico, a SODEBRAS trouxe dezenove artigos acadêmicos, oriundos das mais diversificadas áreas do conhecimento humano. A SODEBRAS -Soluções Para o Desenvolvimento do País -publica artigos científicos das mais diferentes áreas do conhecimento. Devido seu caráter interdisciplinar e a qualidade de seu corpo editorial a Revista tem sido utilizada por pesquisadores do Brasil e do mundo, para publicar estudos de alta relevância para o desenvolvimento técnico-científico da sociedade humana. Além disso, a SODEBRAS conta com o apoio da UNALAR, editora que está no mercado há mais de duas décadas; e também do ITANACIONAL, instituto de ensino e pesquisa localizado em Cisneiros -distrito de Palma-MG. Para contribuir com uma dinâmica ainda maior, no que diz respeito à circulação e a produção do conhecimento, a SODEBRAS adota uma periodização mensal. Sabe-se que em um mundo de rápidas mudanças e de constantes transformações a ciência precisa estar na vanguarda da propagação de informações. Além disso, as edições possuem formato eletrônico de acesso livre e gratuito, assim como indexação nacional e internacional. Acesse nossa página e acompanhe os editais para as próximas edições do International SODEBRAS Congress e participe de um congresso internacional com a possibilidade de publicação em revista qualificada no estrato B2.

Instituto Scientia eBooks, Oct 20, 2022

Os carotenoides são pigmentos naturais que possuem diversas aplicações para a indústria de alimen... more Os carotenoides são pigmentos naturais que possuem diversas aplicações para a indústria de alimentos, além das suas propriedades interessantes para a saúde. Muitos estudos apontam a importância da extração, quantificação e identificação desse composto em diversas fontes. Quando se trata de frutos os compostos bioativos são promissores para a recuperação e uso em diversas aplicações. Assim, o presente estudo teve como objetivo realizar uma revisão das atuais pesquisas sobre a forma de extração e quantificação e/ou identificação do carotenoide utilizando solventes euteticos como solvente extrator. A pesquisa bibliográfica foi realizada em novembro de 2022 na base de dados Science Direct. Os artigos considerados para essa pesquisa foram os publicados entre 2021 a 2023 pois buscou-se a delimitação em estudos recentes. Para a busca, os seguintes termos foram utilizados: "Deep eutectic solvents", "carotenoids". Foram encontrados 75 artigos, assim, a pesquisa consistiu em buscar os solventes euteticos usados, a amostra, a razão molar dos solventes e sua forma de síntese. O receptor de ligação de hidrogênio mais usado na preparação de DES é o cloreto de colina devido sua amplamente disponível, de baixo custo, biodegradável e não tóxico. Os DES obtiveram a mais alta eficiência de extração com alta tensão superficial, polaridade, condutividade, pH e baixa viscosidade e densidade. Os carotenoides extraídos utilizando este solvente apresentou melhores estabilidade. Por fim, a utilização de solventes com menor agressão ao meio ambiente é interessante para indústria e consumidores que buscam esse objetivo, além de uma menor toxidade que para a indústrias de alimentos é interessante pois não promove nenhum risco aos seus consumidores.

Multiresponse optimization of biodiesel obtained from a mixture of soybean oil, beef tallow, and waste cooking oil

Biofuels

Brazilian Journal of Development

Os transformadores são importantes equipamentos no setor elétrico e para sua eficiente operação u... more Os transformadores são importantes equipamentos no setor elétrico e para sua eficiente operação utiliza um sistema de isolamento líquido, sendo o mais utilizado o óleo mineral, que é um derivado do petróleo e não é um recurso renovável, portanto, limitado. Nesse cenário destacam-se os óleos vegetais isolantes, que derivam de fontes renováveis e limpas. O crambe (Crambe abyssinica – Família: Cruciferae) é uma oleaginosa que enquanto matéria-prima para produção de óleo vegetal, pode fornecer até 33% de óleo bruto. Estudos preliminares indicam uma ótima estabilidade oxidativa, não é tóxico, nem bioacumulativo e é facilmente biodegradável, reduzindo riscos de contaminação do solo e água. O objetivo desse trabalho foi avaliar o uso do óleo de Crambe como fluído isolante em transformadores elétricos. Primeiro o óleo bruto foi submetido ao refino e após as etapas de filtração, centrifugação, degomagem, neutralização, secagem e aditivação, o óleo foi caracterizado segundo a Norma ABNT NBR 1...

Cadernos de Ciência & Tecnologia, Mar 13, 2018

Este escrito é construído mediante leitura refletida, com interpretação e discussão de um objeto ... more Este escrito é construído mediante leitura refletida, com interpretação e discussão de um objeto e, seguindo antecedentes, pretende harmonizar-se num diálogo acerca de questões essenciais em ciência, tecnologia, inovação e desenvolvimento sustentável. Como medida necessária para desvelar conexões e para interpretar/refletir, fontes adicionais ao trabalho de partida estão sendo exploradas no ensaio, recurso útil, também, para a interação com pares no ecossistema epistêmico. Em adição, a iniciativa de reflexão surge no espaço povoado, entre outros, por agroecologia, desenvolvimento territorial, inovação contextual, política científica e tecnológica, tecnologia social e estudos organizacionais em ciência e tecnologia na sociedade (CTS) 5 . Quanto a essencialidades, a acepção é a do construído -assim se tipifica se e quando o indivíduo ou coletivo dessa forma o realiza. No seguimento e 1 Opiniões e construtos aqui não representam, necessariamente, manifestações de entidades a que os autores são ligados ou mencionadas no escrito. Os signatários ensaístas reconhecem as favoráveis sugestões e recomendações dos profissionais revisores da casa editora. 2 Coletânea organizada no âmbito do Observatório do Movimento pela Tecnologia Social na América Latina/ Nepeas -Núcleo Agroecologia UnB.

Síntese de precursores do bioquerosene a partir de óleo fúsel da indústria alcooleira

Physic Nut Seed Cake Methanation and Chemical Characterization of Anaerobic Bio-digested Substrate

Waste and Biomass Valorization, 2017

Methane (CH4) generation from the anaerobic digestion of vegetal biomass is an important clean al... more Methane (CH4) generation from the anaerobic digestion of vegetal biomass is an important clean alternative form of energy. In this context, the response of the physic nut seed cake to microbial inoculum for biogas and CH4 production was examined in lab-scale biogas anaerobic digesters. Two experiments were carried out with physic nut seed cake stored over 6 and 18 months. The treatments assayed in each one of these experiments included five types of inoculum: water as the control, three different consortia of bacterial isolates from Jatropha seed cake and one bacterial consortium from bio-digested swine manure. The cake stored for 18 months with water showed the highest volume of biogas, with 83.67 mL in 6.54 g of cake after 21 days, but with lower production of CH4. The best concentration of CH4 (84.33%) was obtained from the Jatropha seed cake stored for 18 months when co-digested with the consortium of 14 bacterial isolates. Co-digestion of physic nut seed cake with the bacterial consortium of isolates from Jatropha cake was the best for producing CH4. After anaerobic digestion, substrates had an increase in macro and micronutrient contents, showing potential for biofertilizer production.Graphical Abstract

Crude Oil Emulsions- Composition Stability and Characterization, 2012

Photochemistry of petroleum

Marine Chemistry, 1998

The photochemical weathering of a crude Brazilian petroleum as a film over sea-water by sunlight ... more The photochemical weathering of a crude Brazilian petroleum as a film over sea-water by sunlight has been studied using a combination of analytical tools including elemental analysis, GC, UV-VIS, IR, Fluorescence, and NMR. Fluorescence intensity decreased rapidly upon irradiation, whereas only slight weathering could be observed by GC and IR even after 100 h of exposure to full tropical sunlight.

Progress in Reaction Kinetics and Mechanism, 2001

The current knowledge of photochemical weathering of petroleum and its fractions in the environme... more The current knowledge of photochemical weathering of petroleum and its fractions in the environment is reviewed, mostly in relation to petroleum films over water. Literature results are compared with the authors’ work. The effects of photochemical oxidation of petroleum on the physical and biological properties of petroleum are examined as well as suggested mechanisms for the observed transformations.

Visible light superoxide radical anion generation by tetra(4-carboxyphenyl)porphyrin/TiO2: EPR characterization

Journal of Photochemistry and Photobiology A: Chemistry, 2010

The generation of superoxide radical anion O2− from tetra(4-carboxyphenyl)porphyrin (TCPP) adsorb... more The generation of superoxide radical anion O2− from tetra(4-carboxyphenyl)porphyrin (TCPP) adsorbed on TiO2 in DMSO and irradiated by visible light was studied using EPR spectroscopy and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin trap. A chemical filter was used to remove light with wave lengths <500nm. A multiline EPR spectrum was observed, characteristic of a mixture of two adducts, the first corresponding to

Visible light singlet oxygen production with tetra(4-carboxyphenyl)porphyrin/SiO2

Journal of Photochemistry and Photobiology A: Chemistry, 2013

Abstract The production of singlet oxygen with tetra(4-carboxyphenyl)porphyrin adsorbed on SiO 2 ... more Abstract The production of singlet oxygen with tetra(4-carboxyphenyl)porphyrin adsorbed on SiO 2 irradiated with visible light ( λ > 500 nm) was evidenced by EPR spectra of TEMPO formed by oxidation of 2,2,6,6-tetramethyl-4-piperidone(TEMP) with 1 O 2 . The formation of singlet oxygen was also evidenced by the formation of anthraquinone and oxanthrone as oxidation products of anthracene with 1 O 2 . The absence of the EPR DMPO-O 2 − signal evidenced that superoxide anion was not present. No other oxygen radicals were detected. TCPP and TCPP/SiO 2 were characterized with UV–vis, UV–vis diffuse reflectance and FT-IR spectroscopy.

Visible light production of superoxide anion with MCarboxyphenylporphyrins (M=H, Fe, Co, Ni, Cu, and Zn) free and anchored on TiO2: EPR characterization

Journal of Molecular Catalysis A: Chemical, 2011

Metal carboxyphenylporphyrins: TcPPM, M=H, Fe, Co, Ni, Cu, and Zn, free and anchored on TiO2 were... more Metal carboxyphenylporphyrins: TcPPM, M=H, Fe, Co, Ni, Cu, and Zn, free and anchored on TiO2 were synthesized and characterized. The EPR spectra of TcPPH, TcPPCo, TcPPNi and TcPPZn exhibited only one line attributed to free radicals. For TcPPCu, the spin Hamiltonian parameters were accurately determined: g//=2.186; g⊥=2.055; A//=183Gauss; A⊥=8Gauss and A’Cu-N∼16Gauss. A higher level protocol, UB3LYP/6–31G(df), was applied in order

Ecotoxicology and Environmental Safety, 2008

Toxicity tests were conducted simulating a diesel oil spill in a tropical environment and juvenil... more Toxicity tests were conducted simulating a diesel oil spill in a tropical environment and juveniles of Prochilodus lineatus were exposed to the water-soluble fraction of diesel oil (WSD) for 6, 24, 96 h, and 15 days. The results showed the activation of biotransformation pathways for xenobiotics, through a time-dependent increase of liver GST activity. WSD caused a decrease in hematocrit and hemoglobin content, very likely due to hemolysis. Furthermore, an increase in glucose levels was observed after acute exposure to WSD. A possible lack of cortisol response could also be associated with WSD, since a reduction in plasma cortisol was seen in fish exposed to the petroleum product for 15 days. Moreover, the occurrence of lesions in the gills and even more severe lesions in the liver, should lead to functional damage to both organs, interfering thus directly with fundamental processes for the maintenance of homeostasis in this fish.

Biogeochemistry, 1997

A review of the photochemical processes involved in the degradation of petroleum,its products, an... more A review of the photochemical processes involved in the degradation of petroleum,its products, and some model compounds found in petroleum. Emphasis is given to processes which affect emulsification, water solubility, and toxicity. Waterphase photodegradation is also treated. The interaction of these processes withbiodegradation is discussed. Areas requiring further work are indicated. 96references.

Renewable energy & power quality journal, Mar 1, 2013

Paramagnetic species were characterized in the seeds of radish wild, rice, mustard, wheat, oats, ... more Paramagnetic species were characterized in the seeds of radish wild, rice, mustard, wheat, oats, sorghum, sunflower, soybean, cotton, beans, maize and barley by Electron Paramagnetic Resonance (EPR). Some iron complexes such as goethite, hematite, magnetite, and ferrihydrite, normally present in the soil, were also investigated by EPR, since their signals can, a priori, be present in EPR spectra of seeds. The EPR experiments were performed at X-band microwave frequency (9.3 GHz) on the JEOL spectrometer (JES-PE-3X) from 77 to 385 K and on the BRUKER spectrometer (Elexsys E-580) in a temperature range from 30 to 70 K. In the EPR spectra of the seeds, it was detected the same complex of Fe 3+ found in goethite, with g=2.0±0.1 in all the investigated seeds. In addition, free radicals have also been detected with g=2.004±0.002, on all seeds, and with g=2.013 only in sorghum seeds. The sunflower seeds showed the highest signal intensity of the free radical. During the temperature variation, changes were observed in the spectra, in a manner that at low temperature (30 K), beyond the higher intensity on signal of the goethite and free radical, the spectra of the seeds also showed signal of hematite and traces of Mn 2+ .

Revista Virtual de Química, 2019

Aviation industry consumes about 177 billion liters of kerosene, moving more than 25,000 aircraft... more Aviation industry consumes about 177 billion liters of kerosene, moving more than 25,000 aircraft and 6 billion passengers. To achieve this, civil aviation generated around 781 million tons of CO2 in 2015, corresponding to 2 % of all anthropogenic emissions of this greenhouse gas, with all the energy required coming from fossil sources. This work aims to synthesize 2-isopropyl-5-methyl-2-hexen-1-ol from fusel oil, a sugarcane industry co-product, for the partial replacement of aviation kerosene. The additive obtained mixed in 3 %, 5 % and 10 % contents in Jet A1 kerosene (QAV-1) exhibited viscosity (1,78 mm 2 s-1), flash point (>40 °C) and performance (<-54 °C) the current international standards, in addition to a potential biodegradability superior to fossil kerosene and a calorific value estimated in the mixture compatible with those required by ANP n° 37.

Revista Virtual de Química, 2017

The biodiesel industry currently produces 260.000 tons per year producing glycerin as byproduct w... more The biodiesel industry currently produces 260.000 tons per year producing glycerin as byproduct which finds absorption difficulties in the market that uses 30 thousand tons per year. The textile industry produces about 3.4 million tons. of polyamides worldwide, which are used in clothes making and about 15-51% of the fabric is discarded as waste. This work aimed the reusing of textile polyamide 66 waste using glycerin from biodiesel adding value to these supply chains. The procedure consists in heating crude or pure glycerin to 190 °C and the addition of textile fabric waste and water as a non-solvent producing recycled polyamide 66 powder. The thermal analysis showed the thermal behavior remained like polyamide 66 showing a decay in 461 ° C and some decays for the contaminants in crude glycerin like methanol and free fatty acids. The recycled polyamide 66 melting point ranged from 253°C to 257°C indicating low polymer degradation. The 13 C-NMR spectroscopic analyzes and infrared spectra exhibited profile similar to the starting material showing the maintenance of the molecular structure. The new process was promising due to the use of two environmental liabilities generated in great amounts, producing recycled poliamide 66 with low costs and good quality.

Research, Society and Development, 2021

Given the great energy demand to meet the needs of modern society, it is essential that new alter... more Given the great energy demand to meet the needs of modern society, it is essential that new alternatives to replace fossil diesel are studied. And biodiesel is an alternative that has been gaining prominence on the world stage, mainly with the use of vegetable oils with a high lipid content, such as Pachira aquatica Aubl, also known as munguba. Given the above, the objective of this work was to extract the oil from the seeds of Pachira aquatica, evaluate the physicochemical characteristics of the oil and define the best conditions for catalytic mixing with temperature variation in the production of biodiesel from the oil obtained. Thus, the acidity index, saponification, refraction, peroxide, water content and fatty acid profile of the oil were evaluated. Fourteen treatments of biodiesel produced with different amounts of sulfuric acid and temperature were evaluated. They were analyzed for water content, specific mass, kinematic viscosity at 40 ºC, refractive index and ester content...

Electron paramagnetic resonance (EPR) or Electron spin resonance (ESR) is a high resolution spect... more Electron paramagnetic resonance (EPR) or Electron spin resonance (ESR) is a high resolution spectroscopy that consists in energy absorption of microwave, for electron spin, in the presence of a magnetic field (Ikeya, 1993). As the name itself suggests, EPR is applied in samples containing some paramagnetic species or used as an investigative method, to verify the presence of some paramagnetic species. Paramagnetism is characteristic of species with a total magnetic moment different from zero.