Enzyme mass transfer coefficient in a sieve plate extraction column

Abstract

The extraction of α-amyloglucosidase was investigated in a sieve plate column using the aqueous two-phase systems formed by sodium sulphate-polyethylene glycol(PEG)-water. The effects of phase flow rate, number of orifices, orifice size, number of plates and phase composition on the fractional dispersed phase hold-up ε_D and volumetric mass transfer coefficient K_Da were investigated in a 60 mm internal diameter sieve plate extraction column operated in a semi-batch manner. It was found that the total hold-up ε_T, dynamic hold-up ε_D and volumetric mass transfer coefficient K_Da increased with an increase in PEG-rich dispersed phase velocity, number of orifices and orifice size, and decreased with increasing phase concentrations. The total hold-up ε_T and volumetric mass transfer coefficient K_Da decreased, while the fractional dispersed phase hold-up ε_D increased, with an increase in the plate spacing. Rational correlations were developed for phase hold-ups and mass transfer coefficients. The contributions to mass transfer during the formation, rise and coalescence of drops were also calculated. It was found that a significant amount of mass transfer occurs during the rise and coalescence stages, while during drop formation it is negligible. Correlations were developed for true mass transfer coefficients (k_D)_r and (k_D)_c.