Photocatalytic degradation of atenolol with graphene oxide/zinc oxide composite: Optimization of process parameters using statistical method

Abstract

A four factor three level Box-Behnken design (BBD) was analysed to define the photocatalytic degradation of atenolol in an aqueous solution in slurry mode. The four different process variables under consideration in BBD model included synthesized Graphene Oxide-ZnO (GO/ZnO) catalyst dose, pH, Atenolol concentration and variation of light intensity. The model predicted the optimum value for maximum degradation rate with conditions set at 1.2 g/L catalyst concentration, pH of 4, 25 mg/l substrate concentration and 940 W light intensity. The first-order reaction rate at this optimum reaction condition is 0.845 min−1. The substrate concentration and light intensity showed highest positive effect on atenolol degradation while pH and catalyst concentration showed negative effect towards atenolol degradation. The data obtained from 29 experiments suggest that maximum rate of reaction (0.783 min−1) has been achieved within 1 h under solar irradiation at pH 6.5 using 25 ppm atenolol concentration and catalyst concentration of 1.25 g/L at light intensity of 1000 W. The model shows high correlation (R2 > 0.953) between experimental and predicted values. It was observed that the rate of degradation with GO/ZnO composite is faster when compared to Graphene/TiO2 composite.