Removal of diethyltoluamide, paracetamol, caffeine and triclosan from natural water by photo-Fenton process using powdered zero-valent iron

The removal of four pharmaceuticals and personal care products (PPCPs), namely diethyltoluamide (DEET), paracetamol (PAR), caffeine (CAF) and triclosan (TCS) (at a spiked concentration of 25 μg/L), from natural water using the photo (UVC)-Fenton (powdered zero-valent iron, pZVI) process was investigated. The results show that a molar ratio of H2O2/pZVI of 2.0, pZVI concentration of 22.4 mg/L and pH of 3.0 maximised the removal of the target compounds at 71.1%, 100%, 64.2% and 87.1%, for DEET, PAR, CAF and TCS, respectively, after 30 min in Fenton (pZVI) process. When this process was coupled with UVC radiation, 29.6%, 80.3%, 3.1% and 88.4% of DEET, PAR, CAF and TCS, respectively, were removed within the first minute, and 99.0%, 100%, 99.5% and 100%, respectively, were removed after 30 min. The pseudo first-order kinetic model best fitted the degradation data of DEET, PAR and CAF (1–20 min); and because 80% of TCS and PAR degraded within the first minutes, it is suggested to explore the kinetics during the initial period. Characterisations of pZVI after the photo-Fenton (pZVI) process indicated the corrosion of the surface of iron powder and the presence of iron oxides and iron hydroxides. Lower removals of nitrate (35–50%), phosphate (<35%) and total organic carbon (TOC,