Enhancement of UV-assisted TiO2 degradation of ibuprofen using Fenton hybrid process at circumneutral pH

A synergistic UV/TiO2/Fenton (PCF) process is investigated for the degradation of ibuprofen (IBP) at circumneutral pH. The IBP decay in the PCF process is much faster than that with the conventional UV, UV/H2O2, Fenton, photo-Fenton, and photocatalysis processes. The kinetics analysis showed that the IBP decay follows a two-stage pseudo-first order profile, that is, a fast IBP decay (k1) followed by a slow decay (k2). The effects of various parameters, including initial pH level, dosage of Fenton's reagent and TiO2, wavelength of UV irradiation, and initial IBP concentration, are evaluated. The optimum pH level, [Fe2+]0, [Fe2+]0/[H2O2]0 molar ratio, and [TiO2]0 are determined to be approximately 4.22, 0.20 mmol/L, 1/40, and 1.0 g/L, respectively. The IBP decay at circumneutral pH (i.e., 6.0–8.0 for wastewater) shows the same IBP decay efficiency as that at the optimum pH of 4.22 after 30 min, which suggests that the PCF process is applicable for the treatment of wastewater in the circumneutral pH range. The lnk1 and lnk2 are observed to be linearly correlated to 1/pH0, [IBP]0, [H2O2]0, [H2O2]0/[Fe2+]0 and ln[TiO2]0. Mathematical models are therefore derived to predict the IBP decay.