Kinetics and thermodynamics characteristics of ultrasonic assisted extraction polyphenols from larch bark.

Effects of ultrasonic assisted ethanol extraction polyphenols from larch bark were investigated, and the related kinetics and thermodynamics were evaluated. The results showed that the optimum extraction process was as follows: ultrasonic power was 350 W, ethanol concentration was 50%, the ratio between the solid and liquid was 1:35 and ultrasonic extraction temperature was 70 ℃, the polyphenols yield was (81.8 2.03) mg/ g under the optimum conditions. Effects of ultrasonic power and time interaction on the extraction of polyphenols were discussed, the kinetic analysis indicated that the Expdec1 model was the best one to fit the extraction course when ultrasonic power less than 300 W(R2 0.994 52); while the Logistic model was the best when ultrasonic power was 350 W(R2 = 0.998 27). The effective diffusivity coefficient value of ultrasonic assisted extraction polyphenols from larch bark was enhanced concomitantly with increasing values of ultrasonic power, while reduced with ultrasonic time increased. The variety of free energy indicated that the ultrasonic assisted extraction method could favor the mass transfer.