Navegando por Assunto "Chemical composition"

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Acesso aberto (Open Access)
Mineralogical and geochemical influences on sediment color of Amazon wetlands analyzed by visible spectrophotometry
(Instituto Nacional de Pesquisas da Amazônia, 2013-09) GUIMARÃES, José Tasso Felix; COHEN, Marcelo Cancela Lisboa; FRANÇA, Marlon Carlos; SILVA, Any Kelly Terra da; RODRIGUES, Suyanne Flavia Santos
Based on sedimentological and geochemical data, this work relates spectrophotometric measurements with sediment composition and its application in palaeoecological studies of Amazon wetlands. The CIELAB values are directly related to mineralogical and chemical composition, mostly involving quartz, iron oxyhydroxides and sulfides (e.g. pyrite), and total organic carbon. Total organic carbon contents between 0.4-1%, 1-2%, 3-5% and 15-40% were related to L* (lightness) data of 27, 26-15, 7-10 and 7 or less, respectively. The CIELAB values of a deposit in Marabá, Pará, were proportional to variations in quartz and total organic carbon contents, but changes in zones of similar color, mainly in the +a* (red) and +b* (yellow) values of deposits in Calçoene, Amapá and Soure, Pará, indicate a close relationship between total organic carbon content and iron oxyhydroxides and sulfides. Furthermore, the Q7/4 diagram (ratio between the % re?ectance value at 700 nm to that at 400 nm, coupled with L*) indicated iron-rich sediments in the bioturbated mud facies of the Amapá deposit, bioturbated mud and bioturbated sand facies of Soure deposit, and cross-laminated sand and massive sand facies of the Marabá core. Also, organic-rich sediments were found in the bioturbated mud facies of the Amapá deposit, lenticular heterolithic and bioturbated mud facies of the Soure deposit, and laminated mud and peat facies of the Marabá deposit. At the Marabá site, the data suggest an autochthonous influence with peat formation. The coastal wetland sites at Marajó and Amapá represent the development of a typical tidal flat setting with sulfide and iron oxyhydroxides formation during alternated ?ooding and drying.
Acesso aberto (Open Access)
Obtenção de extratos de mururé (brosimum acutifolium) por extração sequencial em leito fixo via scCO2: isotermas de rendimento global, perfil químico e atividade antioxidante
(Universidade Federal do Pará, 2022-06-30) SOUSA, Kelly Roberta Pinheiro de; CARVALHO JÚNIOR, Raul Nunes de; http://lattes.cnpq.br/5544305606838748; https://orcid.org/0000-0002-4433-6580
The species Brosimum acutifolium Huber, popularly known as mururé da terra firme, exhibits therapeutic characteristics responsible for its use in folk medicine as antiinflammatory, bactericidal, ant syphilitic, antirheumatic and among others, due to the significant presence of phenolic compounds. This work, then, aims to perform an extraction via supercritical fluid (SFE) in a sequenced way with: CO2; CO2+ EtOAc; CO2+ EtOH, evaluating the parameters of the extraction process, to carry out an evaluation of the chemical composition and the antioxidant activity of the extracts. Therefore, a proximate characterization of the raw material (moisture, ash, lipids and proteins) was carried out, and the average particle diameter was determined. For the EFS tests, the dynamic extraction time (Td) with CO2 was 60 minutes and CO2 flow rate of 3 L/min, Td of 60 minutes for CO2+ EtOAc and flow rate of 1.18 ml/min and Td of 60 minutes for CO2+ EtOH and CO2 flow rate of 1.34 ml/min, and raw material mass of 10 g. The selection of the temperature and pressure variables was based on the difference in the density of CO2 + co-solvent, the isotherms of 40°C and 60°C combined with the pressure values of 250, 300 and 350 bar. The results of the proximate characterization were in agreement with the literature, nominal values of moisture (%) (13.63), 0% lipids, ash (%) (2.12±0.05) and proteins (g/100 mL) (4.41±0.10), with mean particle diameter of 0.456 mm. Regarding the process parameters, the SFE global yield values on a dry basis were better in the extraction conditions with CO2+ EtOAc at 40° C and 60° C at 350 bar and in the extraction with CO2+ EtOH at 40° C and 60 °C at 250 bar. The evaluation of the chemical composition by high performance thin layer chromatography (CCDAE) allows us to infer that the extract obtained in the CO2+ EtOH system in the condition (40° C at 250 bar) showed a better chemical profile in relation to phenolic compounds, flavonoids and fatty acids. , it is noteworthy, however, that the extracts obtained in the CO2+ EtOAc system, under conditions of 40° C and 60° C at 350 bar, exhibited a more evident profile of coumarins in relation to the other extracts evaluated. Regarding antioxidant activity, all extracts showed good activity. Thus, the results made it possible to characterize the matrix in the aforementioned aspects, revealing information that is not available in the researched literature, in addition to inferring the best operational conditions in terms of yield, for the EFS extraction of this raw material based on the operational parameters analyzed.
Acesso aberto (Open Access)
Otimização do processo de extração do óleo essencial de priprioca (Cyperus articulatus L.) por arraste com vapor
(Universidade Federal do Pará, 2009-05-29) CORUMBÁ, Lorena Gomes; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173
It is analyzed the process of extraction of the essential oil of priprioca (Cyperus articulatus L.) rhizomes experimentally with water steam, in a prototype in bench scale. Through design of experiments and response surfaces methodology, they are considered the optimal conditions to maximize the response variables yield and mustakone concentration, majority component of the essential oil of priprioca, in function of operational entrance variables of the process. The independent variables and respective levels are: load or mass of priprioca rhizomes, in grams (64, 200, 400, 600, 736); granulometry of the rhizomes, in millimeters (0,61; 1,015; 1,6; 2,19; 2,58) and extraction time, in minutes (44, 60, 90, 120, 140). Using a central composite design, with aid of the application StatisticaR 7.0, mathematical models are proposed for the responses in function of the isolated independent variables and of their combinations. It is verified that the yield in essential oil and the mustakone tenors can be fitted appropriately for second order polynomials models. They are obtained larger yield simultaneously in oil and mustakone tenors, when the load of rhizomes varies from 105 to 400 grams for extraction times between 105 and 140 minutes.