Unsaturated Esters
Mostrando 1-12 de 74 artigos, teses e dissertações.
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1. EVALUATION OF THE RELATIVE PROTECTION FACTOR OF ROSEMARY EXTRACT IN BIODIESEL IN THE PRESENCE OF TRANSITION METAL IONS
Biodiesel contains unsaturated methyl esters making it susceptible to oxidation reaction. Among the factors that cause oxidative instability is the contamination by transition metal ions that in small quantities catalyze the oxidation reaction. The objective of this work was to evaluate the relative protection factor of rosemary extract, in biodiesel, in the
Quím. Nova. Publicado em: 2020-09
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2. APRESENTAÇÃO - História Antiga: Diferentes Perspectivas
Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic,
Rev. Bras. Hist.. Publicado em: 2020-08
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3. Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy
Biodiesel is a suitable alternative to replace the petro-diesel. The biodiesel is formed by unsaturated esters easily degraded by interferences of oxygen, temperature, contact with metals or contaminants. The aim of this research was to investigate the biodiesel degradation process via 1H nuclear magnetic resonance (NMR) spectroscopy, observing the olefinic,
J. Braz. Chem. Soc.. Publicado em: 2020-08
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4. Influence of Fatty Acid Methyl Ester Composition, Acid Value, and Water Content on Metallic Copper Corrosion Caused by Biodiesel
Oxidative stability parameters (OSP), acid value (AV), water content (W), and the metallic copper corrosion rate in biodiesels obtained from eight different vegetable oils were determined. Simple and multiple linear regression models were constructed to explain the influence of the OSP, AV and W variables on the corrosion rate. The corrosion rate was lower i
J. Braz. Chem. Soc.. Publicado em: 12/08/2019
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5. Influence of Copper and Metallic Alloys on the Oxidation Reaction of Commercial Biodiesel in Mixture with Natural Antioxidant
The purpose of this research was to evaluate the influence of metallic alloys and copper in the degradation of biodiesel in mixture with blackberry extract. Biodiesel is formed by unsaturated esters highly susceptible to the oxidation reaction. The initial induction period (IP) of the control sample was 9.53 h and, after 208 days, the IP reduced to 5.74 h. H
J. Braz. Chem. Soc.. Publicado em: 2019-01
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6. Variation analysis of bacterial polyhydroxyalkanoates production using saturated and unsaturated hydrocarbons
ABSTRACT Polyhydroxyalkanoates (PHA) are efficient, renewable and environment friendly polymeric esters. These polymers are synthesized by a variety of microbes under stress conditions. This study was carried out to check the suitability of waste frying oil in comparison to other oils for economical bioplastic production. Six bacterial strains were isolated
Braz. J. Microbiol.. Publicado em: 2017-12
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7. Application of Full Factorial Design to Evaluate the Effect of Different Variables on the Stability of Biodiesel:Diesel Blends under Storage Conditions
Biodiesel is obtained from a renewable source and has been used as an alternative to fossil fuels. It has unsaturated fatty acid methyl esters that can degrade due to oxidation of the double bonds. The instability of biodiesel during storage may cause problems regarding the maintenance and operation of motors. This work evaluated the effect of several variab
J. Braz. Chem. Soc.. Publicado em: 2017-10
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8. COMPOSIÇÃO QUÍMICA E TEMPERATURA DE CRISTALIZAÇÃO DE ÉSTERES OBTIDOS DE QUATRO ÓLEOS VEGETAIS EXTRAÍDOS DE SEMENTES DE PLANTAS DO CERRADO
The seed oils from four plants (Scheelea phalerata, Butia capitata, Syagrus romanzoffiana, Terminalia cattapa) found in Mato Grosso do Sul were extracted at good yields. Alkaline transesterification of these seed oils to esters using methanol and ethanol was studied and also produced good yields. Oleic acid (30.5/32.3%), lauric acid (30.7/32.9%) methyl and e
Quím. Nova. Publicado em: 2015-03
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9. Metabolite profiling of Schizochytrium sp. by GC-MS, an oleaginous microbial source of biodiesel
The chemical screening carried out on Schizochytrium sp. biomass led the identification of 24 types of organic compounds belonging to n-alkanes, 1-alkenes, 1-alkanols, free fatty acids, methyl and ethyl esters of saturated and unsaturated fatty acids, saturated tri- and diglycerides, unsaturated monoglycerides, wax esters, sterols, triterpenes, and mono- and
Braz. J. Microbiol.. Publicado em: 2014-06
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10. Estudo teórico e experimental de espectros infravermelho de ésteres de ácido graxo presentes na composição do biodiesel de soja
In this work, theoretical and experimental infrared spectra of fatty acid methyl esters (FAME) contained in soybean biodiesel were analyzed seeking the assignments of the relevant vibrational modes to characterize crude soybean oil and soybean biodiesel. The results showed the usefulness of infrared spectra for monitoring saturated and unsaturated compounds
Quím. Nova. Publicado em: 2012
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11. Compostos voláteis em noni (Morinda citrifolia L.) em dois estágios de maturação
The volatile components of noni at two ripening stages were isolated by headspace solid-phase microextraction using 65 µm Polydimethylsiloxane-Divinylbenzene (PDMS/DVB) fibers and analyzed using GC/MS. Both maturation stages had several compounds in common. Ninety-six compounds were identified, from which octanoic acid (
Food Science and Technology. Publicado em: 2010-03
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12. Cardanol e Eugenol Modificados Uso Como Antioxidante no Controle do Processo Oxidativo do Biodiesel de Algodão / Modified Cardanol and Eugenol Using as Antioxidant on the control of the Oxidative Process in Cotton Biodiesel
Biodiesel is composed by a mixture of different kinds of esters that may have unsaturations in their chains. These unsaturations are susceptible to oxidation processes, especially in the presence of oxygen. The oxidative stability of biodiesel becomes therefore an important quality parameter since the oxidation of the esters may cause some problems when usin
Publicado em: 2010