Avaliação da estabilidade oxidativa e determinação da cinética de oxidação de óleos vegetais, ácido oleico e biodiesel utilizando o método PetroOXY (ASTM D7545)
Oxidative stability is a parameter included in the European standard EN 14214 and is closely associated with the quality of biodiesel. The biodiesel is usually obtained in a transterification reaction vegetable oil or animal fat. However, the composition of the raw resources biodiesel is obtained fr...
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| Natura: | doctoralThesis |
| Lingua: | por |
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Brasil
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| Accesso online: | https://repositorio.ufrn.br/jspui/handle/123456789/21671 |
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| Riassunto: | Oxidative stability is a parameter included in the European standard EN 14214 and is closely associated with the quality of biodiesel. The biodiesel is usually obtained in a transterification reaction vegetable oil or animal fat. However, the composition of the raw resources biodiesel is obtained from influences the stability degree of the latter, particularly when biodiesel is stored for long periods of time, causing its degradation, thereby reducing biodiesel quality and making it inadequate for trade. In this thesis, an experimental kinetic study based on the consumption of several synthetic antioxidants added in various concentrations to vegetable oils of moringa (Moringa oleifera), passion fruit (Passiflora edulis) and oleic acid (AO) stored for six and eighteen months at the temperatures 110 °C, 120 °C, 130 °C and 140 °C, as well as biodiesel from soybean (Glycine max L.) and sunflower (Helianthus annuus) oils at the temperatures 130 °C, 135 °C, 140 °C and 145 °C at a 700 kPa pure oxygen pressure, using the ASTM D7545 Method (PetroOXY). It has been obtained a first order reaction kinetic model for oleic acid, soybean biodiesel and moringa oil samples, while for passion fruit oil and sunflower biodiesel samples a zero order reaction kinetic model has been obtained. Parameter
0,CICCCC
determined for the zero order model was related to distinct composition variations of the raw resources. The stability order of samples established using activation enthalpy (ΔHA) was the following: ΔHA (moringa oil) > ΔHA (Passion fruit oil); ΔHA (oleic acid stored for six months) ΔHA (oleic acid stored for eighteen months) and ΔHA (soybean biodiesel) > ΔHA (sunflower biodiesel). In all evaluated temperatures except for 140°C, acid numbers for passion fruit oil with antioxidants added have increased after storage, while for the moringa oil a random behavior has been observed. |
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