Browsing by Subject "Vegetable oils"

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    Advances on kinetics and thermodynamics of non-catalytic supercritical methanol transesterification of some vegetable oils to biodiesel
    (Elsevier, 2018-07-29) Andreo Martínez, Pedro; García Martínez, Nuria; Durán del Amor, María del Mar; Quesada Medina, Joaquín; Ingeniería Química
    Kinetic and thermodynamic parameters of the non-catalytic supercritical methanol transesterification reaction of castor, jatropha, pongamia, tobacco, soybean and jojoba oils to biodiesel production were evaluated in the present study. The experiments were conducted in an 83 ml closed batch reactor at different temperatures (250–350 °C) and reaction times (15–90 min), and at optimal methanol-to-oil molar ratios (15:1 in the case of jojoba wax-oil and 43:1 for the rest of the oils). The pressure reached in the reactor ranged from 10 to 43 MPa. Integral method was used to determine appropriated reaction orders by an adjustment of experimental data to pseudo-zero, pseudo-first and pseudo-second order kinetic equations using Levenberg-Marquardt algorithm. Pseudo-first-order kinetic equation was found to be the most appropriate to describe the supercritical transesterification reaction of the vegetable oils studied. Rate constants and Arrhenius parameters were calculated, the activation energy followed the sequence: castor oil < jatropha oil < tobacco oil < pongamia oil < soybean oil < jojoba wax-oil. It is difficult to explain the behavior of jojoba and castor oils in relation to that of the rest of vegetable oils because they have a very different structure and fatty acid composition, respectively. However, the aforementioned sequence observed for the rest of vegetable oils (jatropha, tobacco, pongamia and soybean oils), which have a similar structure and fatty acid composition, can be attributed to the content of linolenic acid in the oil: the higher the content of linolenic acid, the higher the activation energy and the lower the reaction rate. Finally, thermodynamic study showed that the non-catalytic supercritical methanol transesterification reaction is non-spontaneous (endergonic) and endothermic in nature.
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    Influence of aquaculture waste on fatty acid profiles and gonad maturation of wild fish aggregations at fish farms
    (Elsevier, 2020-02-05) Izquierdo Gómez, David; Sánchez Pérez, Pablo; González Silvera, Daniel; López Jiménez, José Ángel; Martínez López, Francisco Javier; Elbal Leante, María Teresa; Fisiología; Facultades de la UMU::Facultad de Biología
    Wild fish belonging to four species belonging to different trophic groups were captured at three distances from fish farm facilities: long distance (>5 Km), medium distance (1.5 Km) and close to sea-cages. Flesh, brain, liver and gonads were sampled for fatty acid analysis. Fish aggregated near sea-cages showed accumulation of fatty acids of vegetable origin in the studied tissues, due to surplus feed consumption or via predation of fish that consumed the feed. Gonads accumulated vegetable fatty acids in different manner in the different species, and the species least and most influenced by fish-feeds were selected for gonad histological examination. Results showed an acceleration of the final stages of the oocyte development in fish aggregated near fish farms compared to fish captured at long distance. Differences in oocyte development were more acute in the species which incorporated higher quantities of vegetable fatty acids.