Photocatalytic abatement of o-xylene using adsorption enhanced ZnO/GAC catalyst in a continuous flow reactor: Catalytic potential, fate of o-xylene and its by-products

Abstract

Photocatalytic abatement of o-xylene was investigated by immobilized ZnO on granular activated carbon (ZnO/GAC) under UV irradiation. Immobilization of ZnO increased the breakthrough time and removal capacity by 51 and 57%, respectively, in optimal conditions. The catalytic potential of the ZnO/GAC (86.5%) for o-xylene removal was far greater than simple GAC (13.5%), at the optimum condition. The maximum removal capacity with ZnO/GAC (3.12g o-xylene/gZnO/GAC) was observed at 100 °C, while the maximum removal capacity of simple GAC (1.37 g o-xylene/g GAC) was observed a t 20 °C. The main intermediates of the o-xylene oxidation in photocatalytic process with GAC were methanoic acid, o-nitro-p-cresol, phenylmethanal, and methyl di-phenyl-methane. ZnO/GAC can highly catalyze the degradation of o-xylene in the presence of UV, with methanoic acid being the major intermediate desorbed from the bed. The results demonstrated that the ZnO/GAC is an efficient option for the removal of VOCs and biohazards emitted from industrial streams.