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The kinetic model originally developed for quicklime-catalyzed methanolysis of sunflower oil was tested for another three calcium-based catalysts, namely, neat CaO, Ca(OH)2, and CaO·ZnO. This model includes the changing reaction mechanism and the triacylglycerol (TAG) mass transfer. The applicability and generalization capability of this model for heterogeneous methanolysis reaction catalyzed by calcium-based catalysts was evaluated. As indicated by the high coefficient of determination and the relatively small mean relative percentage deviation, the model was a reliable predictor of the time variation of TAG conversion degree in the sunflower oil methanolysis over all four calcium-based catalysts within the ranges of the reaction conditions applied. This model is recommended in general for describing the kinetics of sunflower oil methanolysis over calcium-based catalysts. [ABSTRACT FROM AUTHOR]

A heterogeneous catalyst, ZnO supported on alumina/silica, was synthesized by the sol-gel method. The prepared catalysts were employed for methanolysis of sunflower oil. Effects of various supports as well as calcination temperature were evaluated following the kinetics of the reaction. Simple first-order irreversible and reversible reaction models were applied to determine the reaction rate constant. The results proved that under optimized conditions the catalyst exhibited good activity in the methanolysis of sunflower oil and the kinetics of the methanolysis process could be expressed by the first-order reversible reaction model. For other catalysts with lower activity, the first-order irreversible reaction model could be successfully applied to describe well the process kinetics. [ABSTRACT FROM AUTHOR]

Ripe fruits (berries) of common juniper ( Juniperus communis L.) from northern Montenegro were extracted by hydrodistillation and by supercritical carbon dioxide (SC-CO2) in a single-stage separation system. The composition of the extracts was evaluated by GC-FID and GC-MS. A total of 38 different compounds were identified and significant differences (qualitative and quantitative) were observed between the hydrodistilled oil and the SC-CO2 extracts. In the hydrodistilled oil, major compounds were: α-pinene (28.6-38.2%), sabinene (15.7-20.5%) and myrcene (7.2-18.2%). In the SC-CO2 extracts, major compounds were: α-pinene (7.7-30.3%), myrcene (4.5-20.5%) and germacrene B and D (∼6%). The analysis of the results has shown that the grinding process has a significant influence on the yield and chemical composition of essential oil. In SC-CO2 extraction different pressures were applied and the best process performance regarding chemical composition of the extract and its organoleptic quality was obtained at 90 bar and 40 C in the extraction vessel. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]