ChemInform Abstract: APPLICATION OF A MEMBRANE REACTOR TO GAS‐LIQUID TWO‐PHASE ENZYME REACTIONS: OXIDATION OF GLUCOSE BY SOLUBLE IMMOBILIZED GLUCOSE OXIDASE AND CATALASE

Abstract

The oxidation of glucose to gluconic acid was carried out at 20°C in a membrane reactor in which a solution of glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6) was entrapped between two semipermeable membranes of regenerated cellulose. A buffered solution (pH 5.5) of glucose saturated with oxygen was fed continuously through one grooved compartment outside the membranes (liquid side), and oxygen gas was supplied at a pressure slightly higher than 1 atm to the opposite grooved compartment (gas side). First, by holding one sheet of membrane between the two sides, experiments were performed to determine the membrane permeation coefficient for oxygen in the liquid (kM) and the liquid-to-membrane mass transfer coefficient for oxygen in the liquid (kL). The value of kM was proportional to the difference between the gas-and liquid-side pressures and the value of kL was proportional to the 0.56th power of the liquid flow rate. The reaction studies were done under conditions where the transfer of oxygen was a key process. From individual measurements of the absorption (permeation) rates of oxygen in the liquid through both membranes, it was found that, at low liquid flow rate, the transfer through the gas-side membrane contributed greatly to the global rate of absorption (reaction). For the mixing of enzyme solution, two models were considered ; the stagnant and mixing models. At low liquid flow rate, the rate data were well explained by the stagnant model. At high liquid flow rate, in contrast, the mixing model was applicable. The oxygen pressure and the membrane permeation coefficient were the most important factors affecting the global rate of reaction.