Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components

© 2014 Elsevier B.V.The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (•OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×108M-1s-1) scavenged reactive oxygen species, Cl- (k=-5.3×108M-1s-1) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca2+ at concentrations higher than 50mM (k=-1.3×109M-1s-1) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3- (k=6.9×108M-1s-1) and CO32- (k=3.7×108M-1s-1) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO• generation. Other ubiquitous secondary effluent components including SO42- (k=3.9×105M-1s-1), NH3+ (k=3.5×105M-1s-1) and Na+ (k=2.6×104M-1s-1) had negligible effects. 90% of 17-α-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water.