This work represents the extraction of oil with high
free fatty acid content from spent bleaching earth using sub-critical water
technology as a greener production pathway. The extraction efficiencies under
different conditions were investigated. The studied parameters include
temperatures in the range of 180 to 270°C, the feed to solventfeed-to-solvent
(in this case water) ratio (1:1, 1:2, 1:3, 1:4 and 1:5) and extraction times in the range of 5-60 minutes. The results
showed that the optimum temperature, feed to solventfeed-to-solvent
ratio, and extraction time were 270°C, 1:3, and 20 minutes, respectively. In
another experiment, the extracted free fatty acids were converted into mono-,
di-, and triglycerides through esterification with glycerol to increase the
value added of the extracted products. The kinetics of the extraction process
was found to be corresponding to an irreversible consecutive unimolecular-type
first order reaction, consisting of the extraction step followed by the
decomposition reaction step. Both reaction rates of extraction and
decomposition were estimated using the reaction rate equations utilizing the
nonlinear regression method. The apparent activation energy was calculated to
be 46.1 kJ·mol-1. This result indicates a diffusion controlled
reaction. For more exploration and deep understanding of the extraction
mechanism, other thermodynamic parameters were also calculated and analyzed
including,ΔH#, ΔS#, and ΔG# of the extraction step.
Cite this paper
Fattah, R. , Mostafa, N. , Mahmoud, M. and Abdelmoez, W. (2014) Recovery of oil and free fatty acids from spent bleaching earth using sub-critical water technology supported with kinetic and thermodynamic study. Advances in Bioscience and Biotechnology
, 261-272. doi: 10.4236/abb.2014.53033
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