Reaction mechanism of linuron degradation in TiO₂ suspension under visible light irradiation with the assistance of H₂O ₂

The application of TiO₂/H₂O₂/Vis (visible light) process for the aqueous degradation of linuron (LNR) has been investigated. The performance of TiO₂/H₂O₂/Vis process has been compared with other processes such as TiO₂/H ₂O₂ in the dark, TiO₂/Vis, and H ₂O₂/Vis in terms of LNR decay. The result showed that more than 70% LNR could be decomposed in the TiO₂/H₂O ₂/Vis. The degradation mechanism of LNR by TiO₂/H ₂O₂/Vis process has been verified through investigation of the effects of various radical scavengers on the performance of this system, monitoring the generation of photocurrent, and comparing the intermediates and decay pathways of LNR by UV-TiO₂ and TiO₂/H ₂O₂/Vis processes with 16 and 17 intermediates identified, respectively. It has been revealed that demethoxylation and demethylation through alkylic-oxidation is the major mechanism of LNR degradation while dechlorination (hydroxylation at the chlorine site)anddirect hydroxylationonthe benzene ring is minor in both processes. Mineralization and release of chlorine and nitrogen have been also studied.