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-Fractional dispersed phase hold-up and dispersed side mass transfer coefficients for bovine serum albumin (BSA) and amyloglucosidase (AMG) were measured in 50 mm id. York-Scheibel cohunas using salt-polyethylene glyco1(4000), potassium phosphatePEG and sodium sulphate_PEG, systems. The effect of column height and the effect of phase compositions of the aqueous phase system were studied. The critical impeller speed for flooding and the critical superticial dispersed p&e velocity for flooding were measured. Empirical correlations have been developed for fractional dispersed phase hold-up and dispersed side mass transfer ccetBcients. The performance of the York-Scheme1 column has keen compared with that of the spray column. lNTBODUCTlON The hydrodynamic and mass transfer characteristics of spray columns were described in Part I. The dispersed phase hold-up (ce) was found to be in the range of 0 to 4% and the dispersed side mass transfer coefficient (&,_a) was in the range of lo-' to 1O-4 s-'. For increasing the values of .sD and k,g offered by spray columns, the average drop size needs to be reduced. This can be conveniently done either by providing mechanical agitation or by using a packed column. In both the cases, the levels of turbulent shear stresses are high and as a result the equilibrium drop size is small. The small drops give high liquid-liquid interfacial area. However, they limit the throughput of the phases because of the possible flooding. This drawback is overcome in the York-Scheibel extraction equipment by providing a coalescence zone after every mixing section. In the published literature there is no information on mass transfer characteristics of York-Scheibel extraction columns (Scheibel, 1983) employing aqueous two-phase systems. Blomquist and Albertsson (1972) have presented some preliminary work in this area. The present paper is concerned with measurement of fractional dispersed phase holdup and dispersed side mass transfer coefficient for enzyme and protein in aqueous two-phase systems.