The effect of NOM to TiO2: interactions and photocatalytic behavior

Natural organic matter (NOM) is ubiquitous in aquatic environment, which plays a predominant role in the sorption of pharmaceuticals onto the TiO 2 nanoparticles. It is a matter of concern whether NOM could act as a surface sensitizer of TiO 2 or not. In this context, the role of NOM is investigated for the photocatalytic degradation of carbamazepine (CBZ) using TiO 2 . Four different ratios of NOM:TiO 2 were used varying from 400 μg g −1 to 400 mg g −1 . The findings reveal that small amounts of NOM could enhance the TiO 2 efficiency up to 8%. Electron paramagnetic spectroscopy (EPR), along with size exclusion chromatography with dissolved organic carbon detection (SEC-OCD) and nuclear magnetic resonance spectroscopy (NMR) reveal the occurring mechanism. TiO 2 binds small molecular size fractions of NOM and breaks aromatic bonds of adsorbed NOM transforming it to stranded alkyl groups. This modified TiO 2 bears a significant amount of electrons (e − ) and lesser holes (h + ) than the purified TiO 2 and when irradiated, produces hydroxyl radicals which degrade CBZ.