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Prado A.G.S.,University of Brasilia | Pescara I.C.,University of Brasilia | Evangelista S.M.,University of Brasilia | Holanda M.S.,University of Brasilia | And 3 more authors.
Talanta | Year: 2011

Biodiesel and diesel-like have been obtained from soybean oil by transesterification and thermal cracking process, respectively. These biofuels were characterized as according to ANP standards by using specific ASTM methods. Ethanol, gasoline, and diesel were purchased from a gas station. Deacetylation degree of chitosan was determined by three distinct methods (conductimetry, FTIR and NMR), and the average degree was 78.95%. The chitosan microspheres were prepared from chitosan by split-coating and these spheres were crosslinked using glutaraldehyde. The surface area of microspheres was determined by BET method, and the surface area of crosslinked microspheres was 9.2 m 2 g -1. The adsorption isotherms of cooper, nickel and zinc on microspheres of chitosan were determined in petroleum derivatives (gasoline and diesel oil), as well as in biofuels (alcohol, biodiesel and diesel-like). The adsorption order in all fuels was: Cu > Ni > Zn. The elution tests presented the following preconcentration degrees: >4.5 to ethanol, >4.4 to gasoline, >4.0 to diesel, >3.8 to biodiesel and >3.6 to diesel-like. The application of chitosan microspheres in the metal ions preconcentration showed the potential of this biopolymer to enrich fuel sample in order to be analyzed by flame atomic absorption spectrometry. © 2011 Elsevier B.V. All rights reserved. All rights reserved. Source


Prado A.G.S.,University of Brasilia | Moura A.O.,University of Brasilia | Holanda M.S.,University of Brasilia | Carvalho T.O.,University of Brasilia | And 8 more authors.
Chemical Engineering Journal | Year: 2010

Brazilian sawdust samples (Caryocar spp.; Manilkara spp.; and Tabebuia spp.) have been used for Pb(II) ions adsorption from water at 25°C. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the sawdust with Pb(NO 3) 2 solutions, which gave the maximum number of moles adsorbed as 89.10±8.28; 145.04±12.43 and 95.31±8.28mgg -1 for Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively. Thermodynamic data of interactions were studied by the calorimetric titration of Pb(II) in aqueous solution. Gibbs free energies were negative for all systems and the adsorption interactions presented the following exothermic enthalpic values: -1.99±0.11; -3.20±0.21 and -2.27±0.11kJmol -1 for Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively. All liquid/solid interface adsorptions were entalpically and entropically driven. These sawdust samples were applied to remove Pb(II) from wastewater of a battery industry of Brasilia, DF, Brazil, which presented a Pb(II) concentration of 2.66mgL -1. The Pb(II) concentration in this wastewater was reduced to 2.49; 0.45 and 0.47mgL -1 by application of Caryocar spp.; Manilkara spp.; and Tabebuia spp., respectively. © 2010 Elsevier B.V. Source


Prado A.G.S.,University of Brasilia | Andrade R.D.A.,University of Brasilia | Andrade R.D.A.,Federal Institute of Technologic Education of Rio Verde | Braga J.W.B.,University of Brasilia | Suarez P.A.Z.,University of Brasilia
Journal of Thermal Analysis and Calorimetry | Year: 2012

Biofuel has been obtained by cracking of soybean (Glycine sp.) oil, which is characterized by acidity index, density, cetane index, copper corrosion, carbon residue, fulgor point, and heat of combustion. In order to evaluate the quality of biofuel as well as detect its adulteration with vegetable oil, partial least squares regression calibration models based on thermogravimetric (TG) analysis were used as a precise and an accurate method. Thirty mixtures of biofuel/diesel/vegetable oil standards were prepared. Twenty of them were used for calibration, and ten for validation. The results have shown that the thermogravimetric analysis, PLS/TG, presented the best performance for the detection of vegetable oil contamination with a root mean square error of prediction (RMSEC% w/w) of 0.23, with a relative error of prediction of 3.6%, corroborating with the success of TG analysis application to determine the quality of biofuels and diesel/biofuel blends, showing that the TG analysis is an excellent tool to control quality of biofuels. © Akademiai Kiado, Budapest, Hungary 2012. Source


Andrade R.D.A.,Federal Institute of Technologic Education of Rio Verde | Faria E.A.,Federal Institute of Technologic Education of Rio Verde | Silva A.M.,Federal Institute of Technologic Education of Rio Verde | Araujo W.C.,Federal Institute of Technologic Education of Rio Verde | And 3 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2011

The Brazilian government has presented a biofuel program, which aims the addition of 2% of biofuel in fossil diesel in 2008 and 5% up to 2013. Thus, the knowledge of heat of combustion of biofuel/diesel blends is necessary. The biodiesel was produced by transesterification of soybean oil with a yield of 87%. The diesel-like was obtained by pyrolysis of soybean oil. This biofuel presented all parameters according to ANP. The obtained heats of combustion were 41.36 ± 0.17; 38.70 ± 0.16; and 36.71 ± 0.17 MJ/kg for diesel, diesel-like and biodiesel, respectively. The results show that the heats of combustion of biofuels are approximately 17% smaller than fossil diesel. The obtained data also show that the heats of combustion depend on the methodology used for the biofuel production. Addition of biofuels to traditional diesel fuel results in a linear decreasing of the heat of combustion with the amount of the alternative fuel added to the diesel. © 2011 Akadémiai Kiadó, Budapest, Hungary. Source

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