Mass transfer, kinetics, and thermodynamics studies during the extraction of polyphenols from Feijoa sellowiana peels

Mass transfer mechanism, kinetic behavior, and thermodynamics analysis during the microwave-assisted extraction of total polyphenols from Feijoa sellowiana peels have been investigated with aqueous ethanol (60%, v/v) under several temperature values (295, 298, 301, and 304 K). Diffusion coefficient (1.446 x 10(-10), 2.576 x 10(-10), 2.320 x 10(-10), and 5.653 x 10(-10) m(2) s(-1)), mass transfer coefficient (0.2335, 0.3520, 0.3555, and 0.9724), and Biot number (690.23 x 10(3), 584.16 x 10(3), 655.00 x 10(3), and 735.36 x 10(3)) increased by temperature. Pseudo-wfirst-order kinetic model described the kinetic data better over the pseudo-second-order kinetic model. Activation energy (106.30 kJ mol(-1)) calculated for the current system denotes an extraction process controlled by the reaction, rather than diffusion. Thermodynamics terms such as enthalpy (12.87 kJ mol(-1)), entropy (0.068 kJ mol(-1)K(-1)), and Gibbs free energy changes (-7.187, -7.390, -7.595, and -7.799 kJ mol(-1)) have been also evaluated to comprehend the nature (an endothermic and spontaneous process leading to more irregularity) of the extraction system. Practical applications Comprehension of mass transfer mechanism and kinetic behavior during the solid-liquid extraction by application of microwave irradiation would let the estimation of process conditions for industrial fulfillments. Additionally, evaluation of the thermodynamic parameters would provide information on the nature of the microwave-assisted extraction of polyphenols from Feijoa sellowiana peels.