Degradation of bisphenol A by the UV/HO process: a kinetic study.

A theoretical and experimental study of bisphenol A (BPA) degradation by the UV/HO process in water is presented. The effects of the HO concentration and the specific rate of photon emission (E) on BPA degradation were investigated. A kinetic model derived from a reaction sequence was employed to predict BPA and hydrogen peroxide concentrations over time using an annular photochemical reactor in batch recirculation mode. The local volumetric rate of photon absorption (LVRPA) inside the photoreactor was computed using a Line Source with Parallel Plane emission model (LSPP). From the proposed kinetic model and the experimental data, the second order rate constants of the reactions between hydroxyl radicals and the main reacting species (HO and BPA) were estimated applying a nonlinear regression method. A good agreement between the kinetic model and experimental data, for a wide range of operating conditions, was obtained. For BPA, HO, and TOC concentrations, the calculated root means square errors (RMSE) were 2.3 × 10, 9.8 × 10, and 9.0 × 10 mmol L, respectively. The simplified kinetic model presented in this work can be directly applied to scaling-up and reactor design, since the estimated kinetic constants are independent of the reactor size, shape, and configuration. Further experiments were made by employing low BPA initial concentration (100 μg L) in water and real wastewater. A lower degradation rate of BPA was observed in the real wastewater, although the UV/HO process has also been able to completely degrade the target pollutant in less than 1 h.