Response surface optimization of the photocatalytic degradation of atenolol using immobilized graphene-TiO2 composite

Photocatalytic processes using semiconductors have been widely explored due to their fascinating benefits in environmental remediation. In this study, a four-factor three-level Box-Benkhen design (BBD) was employed to assess the photocatalytic degradation of atenolol (ATL) using immobilized graphene-TiO2 as a photocatalyst. The four variables that were considered in the BBD model were the photocatalyst concentration (10%-20%), pH (4-9), ATL concentration (10-30 mg/L), and light intensity (60-260 W/m(2)). A monolithic-type swirl-flow reactor, which allowed the immobilization of the photocatalyst, was employed in a semi-batch system to study the photocatalytic degradation kinetics of ATL. The optimum conditions where the highest rate constant (0.667 min(-1)) was observed were graphene-TiO2 concentration of 10%, pH of 6.5, ATL concentration of 30 mg/L, and light intensity of 160 W/m(2). The developed model well predicted the observed values indicated by a high R-2 of 0.897. Reaction rate constants obtained herein using graphene-TiO2 in immobilized form were compared with slurry system and TiO2.