Kinetic modeling of the photocatalytic degradation of acetaminophen and its main transformation product using TiO2 nanotubes

Abstract

In this study, a kinetic model of the heterogeneous photocatalytic degradation of acetaminophen (APAP) and its main transformation product is presented. The mechanistically kinetic model incorporated the modeling of the radiation field in the reactor with a Monte Carlo simulation. Experiments were carried out in a reactor operated in batch mode, with the use of TiO2 nanotubes as photocatalyst and an irradiation at 254 nm (UVC). Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Later, the intrinsic expressions to represent the kinetics of APAP and its main transformation product were derived. The predicted results of the kinetic model show a concordance with the experimental data, however, experimental results showed that most of the APAP degradation was due to a photolytic process and not due to a photocatalytic process. Since the photolytic process was not incorporated into the model, it is necessary to adjust the proposed kinetic model for incorporating photolytic radiation; or the proposed model could be adjusted for the evaluation of the photocatalytic degradation of another drug that does not have photolysis under UVC.