Average and local oxygen transfer properties in bubble column with axial distribution of immobilized glucose oxidase gel beads
Chemical Engineering Science 55 (2000) 5405-5414，-0001，（）：
The steady-state method for measuring the volumetric gas-liquid oxygen transfer coefficient based on the liquid phase kLa and liquid}solid oxygen transfer coe$cient kS using air oxidation of glucose catalyzed by the immobilized glucose oxidase gel beads has been established in a bubble column in which there is an axial distribution of the gel beads along the column height. The authors' previous work showed that the method was successfully applied to an external or internal airlift bubble column since either column has an uniform distribution of the gel beads due to a recirculating liquid #ow. The reasonable determinations of the kLa and kS have been obtained taking into account the observed steady-state axial distributions of both gel beads and dissolved oxygen concentrations as well as an inhibitory e!ect of the intermediate product, hydrogen peroxide on the oxidation rate. Two methods for determining the oxygen transfer parameters kLa and kS, one being for the overall average oxygen transfer properties and the other for the local properties along the column height, have been proposed based on the authors' previous simpli"ed model for the oxygen transfer with air oxidation of glucose catalyzed by the gel beads immobilizing both glucose oxidase and manganese dioxide particles for an e$cient production of calcium gluconate. The former method has provided the average kLa and kS values in a good agreement with the literature values obtained usually by the physical dynamic ethod. The latter method has presented the local values of kLa and kS, which are both almost independent of the column height in spite of the axial distribution of the gel beads. This is probably the"rst report on the determination of kLa and kS taking into account the observed axial distribution of the reacting particles in the normal bubble column.