MEASUREMENT OF OXYGEN-TRANSFER PROPERTIES USING OXIDATION OF GLUCOSE WITH AIR CATALYZED BY GLUCOSE-OXIDASE

The determination of gas-liquid and liquid-solid oxygen transfer coefficients, k(L)a and k(s), from measurement of the steady-state dissolved oxygen concentration, Co,s, was examined by using oxidation of glucose with air catalyzed by glucose oxidase, GO. Free GO and immobilized GO gel beads were employed respectively for determination of k(L)a and k(s). The contactors used were a small-scale aerated stirred cell and a bubble column with draft tube. The kinetic parameters for free GO were almost identical to those in the literature. The difference in the values of k(L)a between the enzymatic and physical methods was found to be attributable to foaming in the enzyme reaction medium. The determination of k(L)a could be applied to the cultivation broths. On the other hand, the rate equation for the immobilized GO gel beads was described in the same form as in the case of the free enzyme except that the utilization efficiency of GO loaded for immobilization, alpha, was introduced into the equation. The k(L)a values in the presence of gel beads were practically equal to those for gas-liquid system. The values of k(s) calculated from Co,s, k(L)a, alpha, the kinetic parameters and the GO gel beads loading agreed satisfactorily with those obtained in physical dissolution.