Enzymatic scavenging of oxygen dissolved in water: Application of response surface methodology in optimization of conditions

In this work, removal of dissolved oxygen in water through reduction by glucose, catalyzed by glucose oxidase - catalaseenzyme, was studied. Central composite design (CCD) technique was applied to achieve optimum conditions for dissolved oxygen scavenging. Linear, square and interactions between effective parameters were obtained to develop a second order polynomial equation. The adequacy of the obtained model was evaluated by the residual plots, probability-value, coefficient of determination, and Fisher's variance ratio test. Optimum conditions for activity of two enzymes in water deoxygenation were obtained as follows: pH 5.6, T = 40 °C, initial substrate concentration, [S] = 65.5 mmol/L, and glucose oxidase activity, [E] = 252 U/Lat excess amount of catalase. The deoxygenation process during 30 s, in the optimal conditions, was predicted to be 98.2%. Practical deoxygenation in the predicted conditions was achieved to be 95.20%, which was close to the model prediction.