GAS-LIQUID MASS-TRANSFER IN STIRRED NON-NEWTONIAN CORNSTARCH DISPERSIONS

Oxygen transfer in colloidal dispersions of 1 to 4 wt % corn starch in water was studied and the characteristic gas-liquid mass transfer coefficients in highly pseudoplastic conditions were obtained, The dispersions prepared were represented by flow behaviour indices between 0.64 and 0.90 and consistency indices between 0.002 and 0.2 Pa.s(n). Mass transfer coefficients from 0.004 to 0.03 s(-1) were obtained corresponding to apparent viscosities between 1 and 40 mPa.s. An equation was proposed to fit most of the data favourably. The presence of an antifoam agent was also considered.