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Int. J. Mol. Sci. 2011, 12(11), 7885-7897; doi:10.3390/ijms12117885

Thin Layer Drying Kinetics of By-Products from Olive Oil Processing

* ,
Department of Mechanical, Energetic, and Materials Engineering, Industrial Engineering School, University of Extremadura, Avenue Elvas s/n, 06006, Badajoz, Spain
* Author to whom correspondence should be addressed.
Received: 1 September 2011 / Revised: 25 October 2011 / Accepted: 31 October 2011 / Published: 15 November 2011
(This article belongs to the Section Biochemistry, Molecular Biology and Biophysics)
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The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20–50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10−11 to 1.406 × 10−9 m2/s in forced convection (ma = 0.22 kg/s), and from 9.296 × 10−11 to 6.277 × 10−10 m2/s in natural convection (ma = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick’s diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order.
Keywords: olive oil residues; thin layer; drying kinetics; diffusion coefficient; activation energy olive oil residues; thin layer; drying kinetics; diffusion coefficient; activation energy
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Montero, I.; Miranda, T.; Arranz, J.I.; Rojas, C.V. Thin Layer Drying Kinetics of By-Products from Olive Oil Processing. Int. J. Mol. Sci. 2011, 12, 7885-7897.

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