Study on extraction kinetics of α-amylase using reversed micelles

Based on two-film theory the kinetic model about α-amylase extraction by CTAB-n-butanol-isooctane solution as the reversed micellar extraction system was established.Varied conditions including initial enzyme activity, stirring speed, pH and ionic strength in aqueous phase, concentration of surfactant and co-solvent were performed on a stirred transfer cell with constant interface to determine the overall transfer coefficients (kL) .The relationship of control type and interfacial area was also studied.The results showed that the slope about the common logarithm of residual enzyme activity to extraction time was constant, which suggested that this kinetic model could agree with extraction process and the relationship of kL with initial enzyme activity were uncorrelated when its activity was at 1105U·L-1 to 4420U·L-1.The process of transfer mechanism was affected by the stirring speed, especially by the conditions such as pH and ionic strength in aqueous phase, and concentration of surfactant and co-solvent.The relative slope of extraction rate to interfacial area was minished contrarily with the increase of pH.Moreover, the mechanism of extraction types was mainly controlled by resistance of interface, cooperation and diffusion when pH was 9.9, 10.8 and 11.9 respectively which was performed at the appointed conditions.It also indicated that the relative slope of extraction rate to interfacial area could be used to evaluate the degree of influence of interface resistance.